Do you think ...

 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5203
Registered: May-04


After all the threads that have been hijacked by the various arguments, here's your opportunity to state a preference and defend your position or ask a question about a specific technology that you've wondered about. We've got a couple of speaker designers that might be able to answer technical questions when they arise. And, there are several members who have experience with numerous design styles in loudspeakers. If this works, it should be interesting. If it doesn't, well, it should only waste a few posts before it dies.




There are two rules I think everyone on this thread should abide by (as I see it now, at least).

1) If you are proposing, defending or presenting a tradeoff of a certain technology or manner of design, you have to explain why you think this is true. Saying the B&W 805's are great speakers isn't an acceptable way to defend a design concept on this thread. Almost any technology can be made to work well if enough money is thrown at the problem. Actually, this isn't about individual speakers. I don't think we need to read the B&W 805 is a great speaker. For that amount of money, it should be. If you want to discuss the B&W 805 or the Bose 901, tell us what about the design you think works or doesn't work. Let's try to keep this to broader concepts of speaker design. At least to begin as broad as two way vs. three way or satellite and sub against full range in one box. We can get to diamond deposition domes vs. ribbon tweeters, if the thread lasts that long. But, if you say a bipole is better than a dipole, you have to defend why you say that.

2) This is not meant to degenerate into name calling or an insult fest against anyone, any brand or any design idea. If you say a planar speaker sounds like three day old pounded dog crap flapping in a paper bag, you have to explain why and not just say because I heard some planars and I didn't like them.

Finally, this isn't a rule but a forgone conclusion. There isn't going to be a winner in this thread. It all obviously comes down to a choice among the different tradeoffs that can and must be made in a loudspeaker. You can argue as vigorously and as often as you like about any design as long as it stays civil. This is meant to make you think and defend your thoughts. If you have to dig out some old spec sheets or send us to a web site, then that should be what you do to make your point.




OK?



 

Silver Member
Username: Thx_3417

Post Number: 878
Registered: May-05
Sorry Jan this is about the B&W series loudspeakers, like the above motioned B&W 805's, so I can't comment on my friends B&W DM 602 then over my JBL control 5?

 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5205
Registered: May-04


Nope. Wouldn't appear to be the correct place to do that.
 

Silver Member
Username: Thx_3417

Post Number: 886
Registered: May-05
What is this lighten up happy hour or something Jan, this is not like you, oh well plan B?

How would it be if I where to say that a friend, has these B&W DM 602 for the mains the B&W forgot what model number it was for the centre, never mind it will come to later, well there placement in the room is not doing them any favours.

With poor bass response, being fitted to wall-brackets, not a good at all, what do you think about wall-brackets?
 

Gold Member
Username: Artk

Albany, Oregon USA

Post Number: 1546
Registered: Feb-05
Yikes, another thread dedicated to how much Jan knows and how we should all adhere to his rules of engagement. Time for a Jancoustics I suppose.
 

Under arrest
Unregistered guest
Yup, Sheriff Vigne rides again!
 

Silver Member
Username: T_bomb25

Dayton, Ohio United States

Post Number: 713
Registered: Jun-05
What is your purpose for this thread talking about peoples choices and fovorites in speakers will not be pretty thats like talking about someones wife,we have been down that road before,so dont expect knowone not to argue or insult.You cant set rules and expect people to abide by them while someone is bashing their fovorite speaker,thats just not gonna happen Jan you cant control everything man.Im in though and im not holding back,Jan you are gonna start a war I hope you know that,well lets get it on!!
 

Silver Member
Username: Thx_3417

Post Number: 890
Registered: May-05
I like that Jancoustics.

I know Jan-fu.....
Upload
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5206
Registered: May-04


If you don't think the rules are fair, you can disregard them. I thought some guidelines about not bashing speakers or each other might keep us from doing just that. If that's the only way this sort of discussion can work on this forum, there's no point in starting. Sorry to have wasted your time. Let's discuss subwoofer cables instead.




 

Silver Member
Username: Thx_3417

Post Number: 898
Registered: May-05
Upload

There is this issue with "Monster cable" at the moment, though I don't like spending more Jan, for where I can find something along the same lines, at a more considerable cost with the same performance.....

Upload

As for what cable I'm using for the sub bass, its cheep, all I did was went to DJ Electronics and picked one up for £4.00, there that's easy peasy?

DJ Electronics
64 Ensbury Pk Rd
Bournemouth BH9 2SL
› View map
Tel. 01202 515073
Fax. 01202 515073
 

Silver Member
Username: Joe_c

Atlanta, GA

Post Number: 976
Registered: Mar-05
I know, lets discuss how SDAT speakers kill other speakers 10 times the price.

Or better yet , lets threaten people who disagree with us!
 

Silver Member
Username: Thx_3417

Post Number: 902
Registered: May-05
Yeah guys lets have a rumble jets VS sharks?
Upload
 

Silver Member
Username: T_bomb25

Dayton, Ohio United States

Post Number: 714
Registered: Jun-05
I wont respond so talk all you want to.
 

Silver Member
Username: Kano

Post Number: 594
Registered: Oct-04
I think the threads title is appropriate, since the actual subject was never stated.

I think the subject is which speaker designs are best for their application.

Planars vs. electrostats Vs. driver/tweeter designs.

Box vs. cylinder subs maybe?

Di-Pole vs. bi-pole vs. bookshelfs for surrounds.


Am I correct Instructor Vigne?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5212
Registered: May-04


That would be included within the original idea, yes. I purposely left the specifics of the idea vague to allow the thread to develop along the lines those taking part felt appropriate. My idea was to enable a discussion of "types". Whether that came down to a this material vs. that material would be left to the course of the thread. How broadly the discussion reached from "cylindrical enclosures compared to enclosures with parallel sides" or "dipole full range vs. subs" can only be determined by how much the participants want to think, possibly research their thoughts and present their ideas
in a civil manner. There seems to be some resistance to holding a discussion on this forum that actively engages those three actions.




 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 455
Registered: Dec-03
Lurking
 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 781
Registered: Sep-04
All designs are compromises.

All compromises are subject to the decisions of their respective engineers.

All solutions are different due to the above decisions.

Therefore there can be no 'best' design, merely better or worse designs. Who says which is worse or better are those who have heard both. Those who have heard both may change their minds in different circumstances (no, not torture). This thread is doomed.

As for the title of this thread, in the immortal words of Bruce Lee:

Do not think - feeeeeel! It is like a finger pointing to the moon. Do NOT look at the finger or you will miss all that heavenly glory.

Regards,
Frank.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5218
Registered: May-04


Come out of your spider hole, T8.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5219
Registered: May-04


Frank - The thread is doomed only if the attempt is made to determine "best". We seem to want to beat each other up until someone submits. I thought this might be a thread where, instead of claiming this product is the best because I like it, we could do nothing more than discuss different compromises in the light of advantages and disadvantages. If you go back to my original post, you'll see I made it pretty clear there would be no winner in this thread. There will be losers, if the thread seeks to have a winner.




 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5220
Registered: May-04


In response to "the finger", I would think it impossible to stay within the spirit of the thread's original intent and seek to explain how a dome tweeter makes us "feel". Bruce would understand that.



I "think" with the approach taken so far, the thread probably is doomed. Those with the most experience are those who would prefer to say the least. Shall we turn our attention to which subwoofer cable sounds best, or not? Red or blue?


 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 457
Registered: Dec-03
"Come out of your spider hole, T8."

:-)
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 458
Registered: Dec-03
I'm not sure how to begin so I'll just blurt out; open baffle.
Next is probably; why?
The biggest challenge along with crossover design is getting the box right. So if there's no box that eliminates the box coloring the music.
Because of the cancellation of the front wave and back wave when they meet the sound field takes on a directional property that minimizes the influence of room reflections in the horizontal plane. Put a ribbon transducer on an open baffle and you can control the vertical dispersion as well. Yes, a smaller sweet spot perhaps but the reflections that occur within the room come late enough that they are not percieved as distortion but rather "ambience".
How's that?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5226
Registered: May-04


Not bad. But, doesn't open baffle lead to a discussion of infinite baffle as a possible solution to open baffle disadvantages? Naturally that means we have to understand the disadvantages of open baffle. This is where I'm afraid this thread might go to sh!t. Too many directions at once.




 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 459
Registered: Dec-03
So it would be better to say "Linkwitz Orion" then defend my position?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5232
Registered: May-04


That's hysterical. But, to how many people? That too could easily be the problem with this thread.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5233
Registered: May-04


http://www.linkwitzlab.com/
 

Silver Member
Username: Thx_3417

Post Number: 925
Registered: May-05
Upload

I always think about the next time I would EQ the home cinema, as settings tend to slip just a little, firstly check it over with the (RTA), then I start the EQ which takes me around an hour.

Once all done, I'll leave it alone, until the next time around or there is a special film show that I'll be putting on for friends, therefore I'll make some special modifications.

And since I've worked in the cinema as a projectionist, it's easy and quite fun at times....
 

Silver Member
Username: Dakulis

Spokane, Washington United States

Post Number: 421
Registered: May-05
So Tim,

Should I just order 5 Orions? If so, how do I get that 5th one to sit on top of my TV without cutting a whole in the ceiling? LOL

Moreover, can "Thor" the thunder god outgun Paul's beloved CVs and his sub (this is terrible, I don't remember what kind of sub Paul has) or should I just keep my M&K?

As for the remainder of your post, I simply would have to have a bunch of your very valuable time to make sense of it, I'm afraid.

So, I'll lurk longer and hope I learn something. For the above, I'll just play the fool, I guess.
 

Silver Member
Username: Thx_3417

Post Number: 928
Registered: May-05
It's an "SVS" "Sounds Very Strange"

Upload
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 460
Registered: Dec-03
When I've seen the Orion in HT there was no center channel though that is a fun idea David.
I think a better example of what I was referring to is the Gilmore Model 2 which some of you probably have seen me mention before. As for Thor outthundering CV's, perhaps. With that driver and EQ to extend the bass shelf it will defintely thunder. There are many subs that will do the same as many manufacturers are now using EQ and Servo control to get controlled extended bass.
 

Silver Member
Username: Joe_c

Atlanta, GA

Post Number: 979
Registered: Mar-05
I cannot see a 3" deep driver outgunning that monster. The Thor claims 17hz response, but there are too many variables associated with that sub, since it is an in-wall setup.
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 461
Registered: Dec-03
What are you looking at?
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 462
Registered: Dec-03
The Thor uses a 12" long throw subwoofer in a 50 liter sealed box with an EQ circuit to extend bass response to 17Hz. You may have been looking at the wrong picture. Just so there's no confusion I'm not making subwoofer comparisons here.
 

Gold Member
Username: Kegger

Warren, MICHIGAN

Post Number: 2637
Registered: Dec-03
Sealed speakers verses ported speakers!

I generally like the sound of a well designed sealed speakers bass and mid bass
better then a ported speakers. I feel it sounds more natural and more like a real
instruement instead of just a thud. Also they don't have the steep rolloff that a
ported design does below the port tuning frequency. My assumtion is that what
we are hearing from a ported speaker is the back waves created inside the cabinet
and not what the driver is actually pushing at us does not sound quite right.

Also in that same sense a sealed sub that does not have a down firing woofer I think
sounds more natural also and I contribute that to not having to bounce off the floor.

What about passive radiator speakers do they tend to fall in the middle? Anyone have
any thoughts on the subject of sealed verse ported and know anything about how the
passive radiator speaker works comparred to the others.

Another plus for sealed speakers is generally the limited movement of the woofer which
in terms gives less feedback to the amplifier. A benefit of ported is speakers is smaller
cabinet size and generally higher spl and or sensitivity.

Just my thoughts and hope this may get the discussions going.


 

Silver Member
Username: Thx_3417

Post Number: 941
Registered: May-05
Welcome to the forums site
For everyone's enjoyment we would like to remind you of the following rules.

No Bad language
No spam
No red meat
No freedom of religion
No equal SPL ratings
And remember all loudspeakers must be approved the department of Jancoustics
Failure to obey these rules well result in the immediate loss of citizenship and deportation to the other forums site enjoy the show.....
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 463
Registered: Dec-03
In general, passive radiator designs don't perform as well as their ported counterparts. A passive radiator is basically a box that flexes. It does allow better bass response than a standard sealed box while keeping the size down however.
I agree that in most cases a sealed box provides more natural and controlled response than ported units. I think you nailed the big issue and that is box size. Sealed subs are nice but if you want deep bass you either make a huge box or add EQ the latter being used by many designers. For big earth-shaking bass that is popular in HT nothing beats a big ported box but I prefer a sealed box for music.
In three way designs the midrange is almost always in a sealed compartment which provides three things.
1. It creates a natural high pass filter which aids in crossover design.
2. It protects the driver from the effects of the woofers back wave.
3. It helps control the cone motion of the mid-range driver.
 

Gold Member
Username: Kegger

Warren, MICHIGAN

Post Number: 2639
Registered: Dec-03
So passive radiator systems would fall in between a sealed box and ported for size
"basically" and how the bass sounds?

So for someone wanting a box smaller then a sealed version but still trying
to keep the sound charicteristics a pasive radiator may be a good comprimise?

What about sensitivity is that generally in between both also?
And how about rolloff below the point where it is say down -3db does it rolloff
gradually generally or is it rather steep?

Sorry about all the questions but I know very little about passive radiators!
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5247
Registered: May-04


Passive radiators are ported boxes as far as how you think about the speakers. You're somewhat confusing what can happen with a PR design. As T8 says, the box is allowed to flex, to change its size, to accommodate lower bass frequencies. But, its roll off after system resonance is still the same as a ported enclosure of any type I know of. A PR is tuned to a frequency where, like a port, some of the movement of the PR is in phase with the woofer and some is out of phase information. The difference in what you hear is similar to a sealed box or infinite baffle in that you are only hearing the pressure wave created by the front of the driver. That is essentially the reason for the acoustic suspensions's deeper bass response; you never hear the out of phase signal from the back wave of the driver. The only output you hear is from the driver's front wave. (A major simplification, I know.) Now take that concept and apply it to a PR where the backwave of the driven speaker is what pushes the PR forward. You can see the complications of that design. The benefit remains the only pressure wave you hear is from the front of the drivers.

I guess it could be debated to some extent, but the benefit of a sealed box has always been sold as deeper bass in a smaller package. An AR-3a was definitely smaller than the JBL's and Altec's of the day. That is somewhat of an oversimplification also, but, again, since you only hear the in-phase signals from a sealed box system, the bass roll of is half what you find in a ported design. The tradeoff here is the efficiency of the system is down 3dB since you do not get the reinforcement of the backwave that you have in a ported design.


 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5248
Registered: May-04


Tim, going back to the open baffle design, how is the cut off frequency determined in relation to the baffle size? Or vice versa? I assume you generally pick a cutoff and then size the baffle to that point. Do OB designs use either a two driver front/rear (dipole within a dipole)arrangement or are they all EQ'd to get reasonable bass extension?





 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 464
Registered: Dec-03
Frequency response of a ported vs. PR speaker are nearly identical. There is considerable debate as to which design is "better" but really, if you want more bass extension and keep a small box a PR is a good way to go.
A sealed box gives "deeper" bass in a smaller package? That's easy to debate. Pound for pound a vented enclosure is going to give more bass extension than a sealed enclosure. Whether more bass extension is better, that is debatable.
In OBs not only is baffle width a consideration but also the height of the woofer on the baffle in relation to the floor as it will give reinforcement also. There are formulas used to determine baffle width by the frequency you want the baffle to support. For example a 2 foot wide baffle will support a frequency to ~190Hz.
You may not need EQ if you have a wide enough baffle and drivers that can deliver low frequencies without the acoustical support of an enclosure (see Gilmore Model 2), although most do use EQ including the Orion. The Orion, however, cheats the need for a very wide baffle by using "wings".
 

Gold Member
Username: Kegger

Warren, MICHIGAN

Post Number: 2641
Registered: Dec-03
Thanks guy's!
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5251
Registered: May-04


"You may not need EQ if you have a wide enough baffle ... "

But, then it becomes an infinite baffle if the dimensions are larger than the longest wave you are trying to reproduce.


 

Gold Member
Username: John_a

LondonU.K.

Post Number: 3715
Registered: Dec-03
Not all speakers are boxes containing diaphragms attached to electromagnets. The following link is to an archived thread from March. It is placed here in response to the original question, concerning different approaches to speaker design.

Quad Electrostatic Loudspeaker 63
 

Silver Member
Username: Thx_3417

Post Number: 974
Registered: May-05
Loudspeakers should be nothing more than a pass-through of information that was originally recorded by the artist or the re-recording mixers, to you, that's what It should be, it should play a roll in how it sounds, it should be accurate, and lots of loudspeakers do, as most loudspeakers have distortion, some to some degree and the louder you play them they all have more, there is the (quads) that sound fantastic but they too will give a distortion Patten.
 

Gold Member
Username: John_a

LondonU.K.

Post Number: 3717
Registered: Dec-03
"Loudspeakers should be nothing more than a pass-through of information that was originally recorded..."

That is what I think, too, Andy. I tried to make the point on Do you listen. Jan has started this thread for a different purpose, I think. But, if we do not agree about what a loudspeaker is for, we are unlikely to be able to agree on strengths and weaknesses of different designs.
 

Silver Member
Username: Joe_c

Atlanta, GA

Post Number: 983
Registered: Mar-05
Tim, I may have gotten crossed here. This is what I thought you were talking about:http://www.thesoundbroker.com/Thor.htm
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 465
Registered: Dec-03
Whoa! Yeah, not what David or I were mentioning. The Thor we mentioned is Siegfreid Linkwitz' sealed subwoofer for use with his open baffle Orion loudspeakers. If you're not familiar with his work you may have heard of the Linkwitz-Riley crossover network which is a widely used 4th order crossover design or the Linkwitz Transform circuit.

"But, then it becomes an infinite baffle if the dimensions are larger than the longest wave you are trying to reproduce."

Hah, and here I thought you weren't going to go there. Yes it would, so the decision "how low do you want to go" is made. Additionally, if you can produce a long enough wavelength with enough brute force you can get away with a smaller baffle. This is pretty tough to do with electro-statics or ribbons. The best way we have to do that right now is a big cone or several big cones.
 

Silver Member
Username: Joe_c

Atlanta, GA

Post Number: 986
Registered: Mar-05
Do you use 1st order's in your Lings Tim?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5254
Registered: May-04


" But, if we do not agree about what a loudspeaker is for, we are unlikely to be able to agree on strengths and weaknesses of different designs."

John - Let me straighten this out before it goes too far. There is no argument in this thread so there can be no "agree" or "disagree". The idea of this discussion is to present the facts, as we know them, concerning various designs and concepts. It is not difficult to "agree" that a horn loaded tweeter will have less horizontal and vertical dispersion that a typical dome tweeter. There should be no "disagreement" that a sealed box, or infinite baffle design, has half the bass roll off per octave of a ported design. Those are simple facts. The thread is not intended to suggest one design is better than another. Please, read the opening post again. I wanted to get people familiar with some basic concepts and "accepted" truths about speaker design in the hope we would all benefit from a little more knowledge without any disagreements. If you can tell us on this thread why the Quads work the way they do, that would be in keeping with the spirit of the thread. It has nothing to do with can the Quads do something better than another speaker; because, for all the things they do well, the Quads have tradeoffs also. It is that give and take of facts, "this does this but it fails to do this", that I would like this thread to stick to.




 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 466
Registered: Dec-03
"Do you use 1st order's in your Lings Tim?"

Yes.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5256
Registered: May-04


And, the reason for using a 1st order X-over would be ... "
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 467
Registered: Dec-03
Minimum phase response, maximally flat amplitude response and it requires the fewest components. I would only use a 1st order in this type of system i.e.; "full range" with a "helper" tweeter crossed very high. The downside is the 6db slope which can allow IM distortion. In this case the combination of the 1st order along with the natural rolloff of the drivers minimizes this issue.
 

Gold Member
Username: John_a

LondonU.K.

Post Number: 3720
Registered: Dec-03
Jan,

I completely agree; had, indeed, read the first post; and made the comment I did, in the way I did, with your original request in mind.

There remains the question of what is it that speakers are actually for, and there is by no means a single, agreed answer to this, as we saw on "Do you listen".

Please continue on crossovers, Tim and others. I was reverting to the original question, having only just discovered this thread.
 

Silver Member
Username: Thx_3417

Post Number: 989
Registered: May-05
John,

Let me say it again

Loudspeakers should be nothing more than a pass-through of information that was originally recorded by the artist or the re-recording mixers, to you, that's what It should be, it should play a roll in how it sounds, it should be accurate, and lots of loudspeakers do, as most loudspeakers have distortion, some to some degree and the louder you play them they all have more, there is the (quads) that sound fantastic but they too will give a distortion Patten.
 

Gold Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 1295
Registered: Feb-04
Andy, have you posted the above paragraph in 3 different threads?
 

Silver Member
Username: Joe_c

Atlanta, GA

Post Number: 987
Registered: Mar-05
Careful Peter, he may throw a picture at you!
 

Silver Member
Username: Thx_3417

Post Number: 992
Registered: May-05
Peter,

Yeah I kinder like the way it sounds, I just like to express my honest feelings, to this company of folks that like there home cinema, as well as there super stereo sound system.
 

Silver Member
Username: Thx_3417

Post Number: 993
Registered: May-05
Yeah I should have thrown a picture at you, but I'm cool at the moment listening to Wolfgang "Amadeus" Motazt on classic fm, therefore I'm chilled, until he stops playing, then I'll throw a picture in for good measures...

Get the picture.
 

Gold Member
Username: John_a

LondonU.K.

Post Number: 3722
Registered: Dec-03
Andy,

I think I understood you the first time. Not only do I agree, I even quoted you. No problem. There are pros and cons in design of everything, including loudspeakers. And different people have different priorities. Let the discussion continue.
 

Silver Member
Username: T_bomb25

Dayton, Ohio United States

Post Number: 725
Registered: Jun-05
Tim,when is the Emma coming out?Im really looking foward to that design.So anything else on the bass response on that speaker any ratings etched in stone?
 

Silver Member
Username: Thx_3417

Post Number: 995
Registered: May-05
John,

Sorry I need to go to "specsavers" I didn't see the quote, until you mentioned it just now, sorry guys.....
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 468
Registered: Dec-03
T-Bomb,
I've been distracted from Emma because of working on a custom design for someone. A very interesting bipole concept.

I've reduced the cabinet volume of Emma sacrificing a couple Hz to tighten up the sound. I've built a prototype pair that still need XOs assembled. It should hit a solid 40Hz (anechoic) on the low end from a 17 liter cabinet.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5316
Registered: May-04


"The downside is the 6db slope which can allow IM distortion."

How about telling us why this happens?


 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 796
Registered: Sep-04
I am no electro-mechanical engineer (though I have dabbled in the past). I've never understood why the only way around the crossover problem is to insert a capacitor (for 1st order) when this gives a 90 degree phase shift to the upper frequencies. Why is it we can't simply design an upper frequency drive unit which has no output below (say) 12khz? Then you wouldn't need a crossover at all.

I guess my question is: Is it so difficult to design 2 or 3 drive units that can work together such that their individual frequency responses take over from each other, thus obviating the need for a crossover with all the waste that entails?

It's a basic question, I know...sorry...
Regards,
Frank.
 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 797
Registered: Sep-04
Jan, sorry if this breaks the rules....
 

Gold Member
Username: Joe_c

Atlanta, GA

Post Number: 1029
Registered: Mar-05
" Is it so difficult to design 2 or 3 drive units that can work together such that their individual frequency responses take over from each othe"

Do you mean that when one driver reaches it's peak hz, the next takes over and so on?
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 476
Registered: Dec-03
"How about telling us why this happens?"

Modular or Intermodular Distortion occurs when frequencies produced by the two sources combine to form new harmonic frequencies not present in the original signal. The possibility of this occuring increases with the larger overlap found in low order crossovers.
 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 800
Registered: Sep-04
Joe,

Something like that. i.e. that the two or three drivers combine to give a uniform phase linear frequency response when all three are plugged into an amplifier.

Regards,
Frank.
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 477
Registered: Dec-03
"Why is it we can't simply design an upper frequency drive unit which has no output below (say) 12khz? Then you wouldn't need a crossover at all."

Actually, Piezo-electric tweeters can do this when used in a loudspeaker circuit. The question then is; Do Piezo tweeters sound good?
I think the problem may be that speaker drivers are not linear devices. They all have peaks and valleys present within their reproductive range. In the Ling, for example, the main driver does roll off at 12kHz which is why in some of my prototypes I didn't use an XO on that driver. The problem was that as the driver approached it's roll off point it experienced a peak in the response curve. It turned out to be better to force it to roll off sooner rather than let that peak occur.
 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 801
Registered: Sep-04
Hmmm, the 4" Jordan aluminium driver was used to great effect in the Acoustic Precision FR-1 as a full-range unit. It had a response up to around 17khz and down to something below 100hz. Admittedly, AP created a crazy cabinet (expanded polysterene) for it, but combine that with a decent subwoofer and a supertweeter and you could be onto something special.

Wilson benesch's latest revision of the Curve loudspeaker has no crossover on the main midrange unit. There are notch filters to the bass and treble units (as I understand it). This has improved the speaker no end.

Regards,
Frank.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5324
Registered: May-04


Frank - I'm obviously not a speaker designer or else I would be on the third of my yachts (the small one for the summer) living off the isle of Capri raking in the millions and millions of dollars all speaker designers make each month; but ... the US dollar has gone to crap anyway.




Your solution is one that leads many speaker "builders" to become speaker "manufacturers". When you can design and build your own proprietary drivers from scratch for each design, you can do more work with less X-over. However, as you know, the progression of a speaker company begins with using drivers designed by another comapny (Focal, SEAS, Vifa, etc.) and making the modifications necessary for your design. That's a bit like going down to the local tire shop and grabbing a few that look round enough and someone who pulls into the lot to take to the F1 race this weekend. The more generic the driver, the more adaptation is required to make it fit your ideas. Particularly, this problem seems to be made worse by people insisting on using strange X-over configurations. The components in the circuit will quite often require some additional frequency compensation in the circuit also unless you want to live with the anomalies of each driver shining brightly through in each design.



Now, as a sideline, what has always fascinated me is the number of speakers designed which utilize a woofer from one company and a tweeter and possibly mid from other companies. Wouldn't you think the same company would have drivers that sound the most alike and require the least amount of compensation? When I hear designs that are one company products, that seems to be the case to me.




OK, back to jamming stuff in a box. As speaker companies increase in size, they seem to get to a point where they have drivers made to their specifications. This usually amounts to taking a stock driver and applying a doping material or altering the spider or so forth. This still is not a ground up design and still has compromises.

When the company finally gets serious about making speakers, they get to a point where they are designing and manufacturing everything that accounts to making sound in their products. Some companies are fortunate enough to begin life this way; KEF, Celestion, JBL, Dynaudio and virtually all of the Canadian companies. But even this is not going to get you to the point where you can do away with X-overs completely.

The designer can design in a roll off at a certain frequency, but as T8 has suggested, that roll off, when done mechanically, is seldom as smooth as when it is controlled by a cap or inductor. So add a cap or an inductor to help it get out of its own way. The same on the other side of the next driver up, the roll up needs some asistance. To rely on purely mechanical means to join the two drivers will give you uneven frequency response and seldom, if ever, allow the drivers to roll off at such a steep rate that it won't, like a 1st order X-over, allow the out of bandwidth distortions to be heard. Add to the problem the varying dispersion properties of the two drivers covering the same range, the same problem you have with common X-overs, and a woofer and tweeter that are 6dB apart in sensitivity and you can easily have a fairly mucked up speaker for all your efforts.

I think the idea you have is one that many speaker designers would like to see arrive as materials and construction principles improve. But, as of today, it seems to still be part of the compromise that everyone faces in audio.




 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 480
Registered: Dec-03
How about another design concept?
Bipole speakers. An example would be two drivers back to back in a cabinet and wired in phase. Both cones move in and out at the same time.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5332
Registered: May-04



Holy figure eight polar patterns, Batman!




 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 482
Registered: Dec-03
It's like there's a pattern to these patterns!
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 483
Registered: Dec-03
In my adventures with full range drivers I came across people proposing a theory that if you mounted two similar drivers back to back in the same cabinet you would have these gains:
1. Increased bass response due to the absence of baffle step. This also eliminates the need to add a baffle step compensation circuit.
2. Increased bass response by capturing the back wave of two drivers and using it to load a port tube.
3. Increased sensitivity.
4. Decreased cabinet vibration due to mechanical cancellation of the drivers motion on the cabinet.
5. Reduced influence from room reflections because of the figure 8 polar dispersion pattern similar to that of dipole speakers.
My first test of this concept was a bipole tapered quarter wave resonator that I called BV1. It used the now rare Radio Shack 40-1197 drivers which were manufactured by Fostex and very similar to the Fostex FE-103 which is a 4" full range driver. It turned out very well and has been duplicated by individuals around the globe. The drivers were heavily modified by doping the cones, putting modeling clay on the frames and removing the dust caps and replacing them with phase plugs.
 

Gold Member
Username: Thx_3417

Post Number: 1094
Registered: May-05
Timn8ter,

Point of fact I'm thinking about building a THX baffle wall to extended, the frequency response down just a bit more lower with the three-screen JBL control 5 and the JBL 4645 sub bass, the cost is cheep with the materials on hand like plasterboard timber etc, and all this makes a hell of a difference to the overall performance, in whole and in part.

Ashley
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5336
Registered: May-04


When I was poking around the DIY forum, I came across the discussion of using the two drivers as bi/dipole configurations. The consensus I got from the discussion was it seemed to work best when the two drivers were loaded into separate enclosures and then the enclosures were joined as one larger single box. Did I misread the information?

This configuration seems to have minimal downsides other than the cost of multiple drivers. So what happens if this is placed on a OB? Hook the drivers out of phase and you should have an interesting application would be my guess. Shouldn't that even solve some of the "brute force" issues of getting slightly deeper bass out of an OB? Maybe down to 70Hz without having to remove a wall in your home to fit the baffle? Which, of course, would then make it an IB.







 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 812
Registered: Sep-04
Of course there's the other dual driver configuration of putting one driver behind the other inside the cabinet - the isobaric principle which also introduces the improved bass response without the out of phase signal of a bipole.

Regards,
Frank.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5347
Registered: May-04


The advantage of the configuration Tim is describing does away with the Baffle Step Compensation circuitry in the connection to the driver. Depending upon attitude, I would think this could make a substantial difference to someone using a single driver, full range design in order to simplify, simplify, simlify.



Frank, how about giving some reasons for using an isobarik loading? As far as I know, it only has ever been applied to low frequency drivers.


 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 493
Registered: Dec-03
"So what happens if this is placed on a OB?"

I'm sorry, I'm unclear as to what you're asking. Are you suggesting front and rear facing drivers on an OB? Sounds a bit like some of the dipole bass units I've seen (the Orion again).
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5349
Registered: May-04

" Are you suggesting front and rear facing drivers on an OB?"

Yes. Does this change the radiation pattern of the speaker over just one driver whose face is firing to the front and basketed assembly is firing to the rear? Or, is this a matter of the low frequency wave being so long the basket materials don't interfere? If that's the case, I guess two drivers facing in a similar direction would acomplish the same thing.


 

Gold Member
Username: Joe_c

Atlanta, GA

Post Number: 1039
Registered: Mar-05
Isn't that how Franks Mani-2's work?
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 494
Registered: Dec-03
The Orion's woofers are wired push-pull but facing front back. This creates the "figure 8" radiation pattern of a dipole and increases the swept air volume while keeping the cabinet narrow.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5356
Registered: May-04


What if this arrangement was extended to the upper frequency drivers where the wavelengths are shorter?
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 495
Registered: Dec-03
You would get the dipole effect with it's benefits but I don't think I'd be very excited to hear the diffraction of the mids and highs reflected from the basket and magnet assembly. As you alluded to, the low frequencies don't suffer from this like the upper ranges do.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5375
Registered: May-04


DOH!!!
 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 819
Registered: Sep-04
Jan

I don't know enough about the theory behind the isobaric principle to talk about it. All I know is that every isobaric I've heard has been good - Linn Isobarik, Dynaudio Confidence 5, Totem Mani-2. The Totem is unique in two ways - 1) it's a ported isobaric design and 2) it's the bass-mid driver(s) which is isobarically loaded, not just the low frequencies. This indicates that the isobaric principle can be used to good effect in more than just the traditional low frequency band.

Regards,
Frank.
 

Silver Member
Username: T_bomb25

Dayton, Ohio United States

Post Number: 823
Registered: Jun-05
But Frank its still very very inefficient and the midrange loses a lot of pressence with nothing less than 200 watt solid state amps and the bass does to,you need gobs of power for the Mani to get anywhere near their potential,its very difficult to get the best out of them.
 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 823
Registered: Sep-04
The midrange does not lose any presence, quite the contrary. Suitably powered the Mani-s are wonderfully expressive in the midrange while going deep with grip and control.

As to the power and inefficiency, yes, this is true, but it was the first speaker in 4 years of looking (!) that beat my old speakers handsomely in every way. Luckily I already had the power so I didn't need to worry about that. And in fact it's current they need, so even a lower powered high current amp such as a Naim 300 (90w/ch) can do the job of driving them.

Regards,
Frank.
 

Unregistered guest
I am surprised that througout this entire thread, no one has mentioned horn loaded designs.

They reduce the number of crossovers and provide a wide dynamic range.

I am not an audiophile but found this discussion very enlightening.

Could someone tell me more about the pros and cons of the horn design?
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 496
Registered: Dec-03
Briefly, there are typically two applications for horn loaded designs. What I think you're referring to is full range drivers in a back loaded horn. The other is used in pro gear.
Horn loading is a good way to increase the acoustic output of a driver in a fashion similar to putting your mouth up to a megaphone or even cupping your hands around your mouth. In that case it's a front loaded horn but the same effect can be applied to the back wave of a driver. It's beneficial in that respect but also a good way of getting reasonable bass response from the many full range drivers that have rising response curves and otherwise miniscual bass. Horn loaded designs are less impactful on system sensitivity than other applications.
The downside is that horns are generally difficult to design and can be quite large in comparison to other applications.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5391
Registered: May-04


Horn loading is the equivalent of using an acoustic transformer. The driven surface area is smaller than the driving surface area. The driver sees a minimal amount of air pressure on its surfaces while, as the horn expands, the apparent surface area of the driver also expands until it eventually reaches the size of the horn mouth. This makes the horn loaded driver a more efficient system with the capability of producing large dynamic peaks; but presents as many disadvantages, in my opinion, as advantages.

First, I don't know where you got the idea horn loading can reduce the number of crossovers. If the speaker is a three way design, it will have four crossover filters; two high pass and two low pass filters. What horn loading does accomplish is possibly reducing the number of components within a XO. Since the horn provides a very steep (24dB per octave) roll off above and below the resonance of the horn, some of the various inductors and capacitors needed in a more conventional design can be minimized. The disadvantage to this roll off is in the need for drivers that can operate over broader frequency ranges with minimal distortion as the XO is made from driver to driver. This is often reflected in the type of driver chosen for a horn loaded design. This also makes a fully horn loaded two way system almost impossible without a tremendous increase in size of the enclosure or a loss in response at one frequency extreme or the other. Therefore, most fully horn loaded systems are three way designs and there goes the idea of reducing the number of components in the XO.

A horn loaded mid and high frequency system has many of the drawbacks of an electrostatic or planar design when it comes to mating with a conventional ported woofer enclosure. The apparent speed of the various drivers seldom matches to the point of seamless integration.

A horn of any sort is going to be large and more expensive to construct than mounting a direct radiator. An expotential horn is even more difficult to built properly, but will reduce the length of the horn's throat. Folding the horn further reduces the footprint of the speaker; but at greater cost and complexity.

Even with today's advanced materials, it is impossible to eliminate the horn's resonances. So frequency response of horn loaded drivers is typically not as flat as a direct radiator design. With this added resonance, the ringing of the horn tends to offset the dynamic capability of the driver.

Dispersion characteristics of a horn are severely limited compared to a direct radiator. In today's home speaker market, that is going against the current trend in design. Horn loading creates hot spots where the full range of the speaker is heard and then rapidly falls off outside of that spot. With its ability to place sound in a specific area and not others, a horn loaded speaker can present unusual problems within a typical domestic setting.

If you load the woofer into a horn, you have no acoustic damping to even out the response of the woofer. This can lead to somewhat boomy bass with some frequencies being boosted and some being cut due to the out of phase signals coming from the horn. Horn loading does nothing to supress the twin impedance peaks of the low frequency system. These impedance swings can begin to drive some amplifiers into an irregular frequency response.

If you are after nothing but overall sesnitivity of the speaker system, a horn loaded design is the best bet. If you are after other qualities of sound, a horn can present many challenges to the designer.




 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5392
Registered: May-04


Here's a link to a site that speaks well of horns:

http://www.ossaudio.com/lothx/LothXhorninfo.htm

Remember, when they discuss phase coherence, it is in relation to a single driver enclosure; not a three way horn loaded system.




 

Gold Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 1368
Registered: Feb-04
The driver sees a minimal amount of air pressure on its surfaces while, as the horn expands, the apparent surface area of the driver also expands until it eventually reaches the size of the horn mouth.

The driver sees increased pressure and moves less.

If you load the woofer into a horn, you have no acoustic damping to even out the response of the woofer.

I'm not sure I understand the meaning, but the driver sees increased pressure and moves less. :-)
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5395
Registered: May-04

I knew Peter would detect the mention of horns and would come running. Defend the honor of your love, good sir!


The way I understand horn loading amounts to this. If the horn is properly designed and built, the horn loaded driver will see increased pressure at and around its resonant frequency only. It's a ported box by another name, Peter. That is why there is a second peak in the impedance of the system just as there is with any ported enclosure.

The acoustic damping remark is in relation to a damped transmission line where the backwave is minimized and delayed by acoustic stuffing. Or, for that matter, most ported speakers that have the ability to at least damp the backwave of the driver.


 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5396
Registered: May-04


Peter - If my understanding of the increasing pressure at resonance is correct, I would guess what is being confused is the nature of the horn in relation to SPL. Since horn loading will produce the highest sound pressure for any given amount of voltage put into the driver, it is true the driver will require less excursion to produce the same SPL as a non-horn loaded design.

While clumsy in wording, what I was trying to explain was the acoustic impedance matching of the horn's throat. Any size driver will see less acoustic impedance from the air pressure on its face than would a driver whose diameter equalled any portion of the horn's throat or mouth. Yet, the driver's "apparent" size is relative to the final dimensions of the horn in its ability to move air.

How's that?


 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5400
Registered: May-04


Now, my question is; does front or rear horn loading of a driver increase the air pressure or the air velocity? I don't think you can do both.


 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 829
Registered: Sep-04
high air velocity = low pressure (according to my o level physics)

Horns suffer other problems though such as cabinet resonances due to the predominantly large panels they're made from. Hence the more successful horn speakers tend to be strangely shaped, making less resonant panels. No doubting they can sound pretty amazing, just a little impractical in terms of size very often.

Regards,
Frank.
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 497
Registered: Dec-03
There are some BLHs that utilize damping and because of folding the horn inherently brace the cabinet reducing panel vibration. This allows for a smaller cabinet. Here's a nice picture of the Buschhorn for example.
http://www.geocities.com/northbirdten/buschhorn_mkii.htm
This enclosure typically utilizes a 4" full range driver. Note the size of the enclosure relative to the driver diameter.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5406
Registered: May-04


That's the first time I've seen a cut away picture of the infamous Buschhorn. With some amount of damping applied to the backwave, it would appear to be a variant of, and I seem to remember reading in Bailey's paper the Buschhorn was the precursor to, the transmission line concept.

Which would bring us to the TL enclosure. Difficult to design and, until recently, tuned "to the ear"; the TL enclosure represents what I have often seen described as the near perfect solution to a speaker enclosure. It has many of the advantages of a low frequency horn loaded design (rigid, self damping enclosure). Along with the advantages of a ported enclosure (reinforces the bass output at and below the driver's resonance). And, the TL also includes the natural dynamics and control through the frequency bandwidth of a sealed box (along with damping the backwave to reduce driver breakup). Though typically larger than a AS or BR design, the TL has been brought down to the size of the LS3/5a with the PMC DB1+.

http://www.pmcloudspeaker.com/db1.html

Overall, I would have to say, to my ears, the TL designs I've heard have had the best bass response of any enclosure design. Their only substantial drawback that I can see is their typical inefficiency; though this is on par with most sealed box systems. To an extent I would consider their steep roll off at the lower limits of the system to be a minimal tradeoff when compared to a sealed box or infinite baffle design. Still, I've not heard and felt bass quite like the large IMF monitors could produce.

Additionally, the TL enclosure can be used with various sorts of drivers (ribbons) and through the entire frequency bandwidth. Here's an example of a TL loaded tweeter that extends down to 150Hz. (http://www.warrengregoire.com/hifi-stereo-microtls.htm)

Peter - Notice the reference in the above link to increasing the pressure on a driver's face in relation to raising the resonant frequency of the driver. Another tradeoff of horns (and most other enclosures also).

http://www.tnt-audio.com/casse/ipls3mtl2_e.html



VIVA, LA TL!!!






 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5408
Registered: May-04


"Now, my question is; does front or rear horn loading of a driver increase the air pressure or the air velocity? I don't think you can do both."

Before Peter tries one of his end 'rounds on this question, I should ammend the question to include "you can't do both as long as the nozzle and the hose remain the same".



 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 498
Registered: Dec-03
Nice seque Jan. Now, imagine a bipole TL.
(hint, hint)
 

Gold Member
Username: Thx_3417

Post Number: 1287
Registered: May-05
Jan,

Looking at the design that Timn8ter, posted of the Buschhorn Mk2 was neat, the frequency will it not be improved by this approach and technique.

Also I saw this and it's built out of bricks and concrete....

And hear is the link DONNA"
http://www.royaldevice.com/custom.htm

it's the wildest thing I've seen.....

Ashley
 

Unregistered guest
Jan,

If I read the article from LothX correctly, the amplitude increases as it travels down the horn and the velocity decreases. I assume your question is rhetorical or pointed specifically at Peter?

I do not see size as being a drawback to horn designs,especially with the wider acceptance of HT and dedicated listening spaces.

Doesn't fewer drivers equal fewer XO's theroretically as the article described in their products?

One last question, who are the major players still mfging horn designs and how do they compare to one another sonically and cost wise?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5410
Registered: May-04


From the LothX page:

"As the pressure wave moves towards the mouth, the pressure decreases and the amplitude increases."

There is no specific mention of velocity in the article that I can find. I may be overlooking something though. It's been quite a long time since I had to carry on an intelligent conversation concering horns; twenty years almost. So time and a few drugs (all legal, but powerful) have not been as kind to my memory as I would prefer. If I remember how the description of horn loading went, it involved going from a high pressure zone to a low pressure zone and velocity increasing as the horn's throat expanded. I'm assuming that is correct as velocity should be the inverse of pressure in this case. (?) So, the question could be viewed as rhetorical; but if anyone would care to make a better description, I'm willing to entertain any ideas. Otherwise I'll have to pull out my "Dope From Hope" binder by Paul Klipsch and start reading.

I made a reference to an article on TL enclosures in an earlier post. I cannot find the article online. If anyone would care to do a search, the information is; "A Non-resonant Loudspeaker Enclosure Design", by A. R. Bailey. It was printed in Wireless World, October 1965. I have a reprint that was distibuted by IMF back in the 1970's. It also contains a second article by Bailey that was printed in 1972 and then three articles on horn design. To my knowledge the 1965 article was the first to promote an acoustic TL design as a reality.


As far as size is concerned, we all have our own limits as to what is "too big". Most people consider horn loaded bass cabinets to be rather large. Certainly given the fashion of speakers being designed today, bass loaded horns have a considerable depth. In a market where baffle step has become a serious consideration, the transition from the mouth of the horns to the closest reflective surface is probably going to be much longer in distance (and time) with a horn loaded bass cabinet such as a Klipsch LaScala than it might be with a more conventional direct radiator design. (http://melhuish.org/audio/horninfo.html





Ashley - That is a "because I can" design. The name of the designer sounds Italian; what do you expect?

But, what happens if you change your mind in the middle of construction?




A dipole TL? Care to tell - and show - me more?




 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5412
Registered: May-04




"White Paper on the Quadratic Throat Waveguide"


http://www.thisplace.com/charliehughes/Articles/Articles-Fr.html




 

Unregistered guest
I read the QTW white paper and did not understand what beaming of the frequencies meant?

In context, the "exponential vertical components still results in producing vertical beaming of the higher frequency?" refering to the Altec design.
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 499
Registered: Dec-03
Actually it's a "bipole" TL variant. Bipole assumes the drivers are wired in phase (push-push), dipole assumes either open baffle or the drivers wired out of phase (push-pull). I only have the prototypes right now. The final cabinet assembly will happen next week. I'll have pictures soon.
I'm using two 4.5" drivers, one firing forward, the other firing to the rear, wired in phase. The forward driver is "full range" (+\-3db 65Hz - 20kHz) and the rear driver is "wide range" (+\-3db 65Hz - 12kHz). There is NO crossover.
The cabinet is a TL variant, technically a "restricted terminus quarter-wave resonator" with a series of internal chambers to control the backwave velocity and pressure.
Typically in this type of design the driver will be placed near the center of the line leaving a chamber above the driver that's nearly the same size as the space below the driver. The cabinet is then filled appropriately with some type of stuffing, either polyester wool or fiberglass. As resonances set up inside the cabinet the frequencies tend to "stack up" with the higher frequencies staying in the upper portion and being slowed by the stuffing and the lower frequencies making their way down to the base where there is usually a port.
In my design the driver has been placed near the top of the cabinet and the series of chambers below the driver perform the function of slowing the upper frequencies and passing the low frequencies to the port. The length and cross-sectional area of the cabinet still provides the benefits of quarter-wave resonance giving me a nice boost in bass response. This has resulted in a very livable size cabinet that's about 40" tall.
"Beaming" has to do with polar dispersion. In many cases as the frequencies rise the sound field is reduced in diameter. The result is the SPL drop off when you're listening off angle increases with the frequency while the on axis SPL remains the same. Simply put, a smaller "sweet spot".
You could do a search for "polar dispersion in loudspeakers" and probably find a more detailed explanation.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5419
Registered: May-04


Westcott - Do you understand what "dispersion" refers to?
 

Gold Member
Username: John_a

LondonU.K.

Post Number: 3739
Registered: Dec-03
Just to say "thanks" to the contributors for a fascinating and instructive thread.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5420
Registered: May-04


Why, you're welcome! Y'all come back now; y'hear?


Here are a few interesting TL designs:

http://www.t-linespeakers.org/projects/nick/index.html

http://www.t-linespeakers.org/projects/steve/

http://www.t-linespeakers.org/projects/nick/aqa.html

http://www.t-linespeakers.org/index.html


The last example here is a design by T8. This is a quarter wavelength resonator; correct, Tim?
And the different styles of quarter wave resonators are ...?

http://www.timn8er.com/shiva_tube.htm


 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5421
Registered: May-04


Sorry, I missed an interesting page:

http://www.t-linespeakers.org/sitemap.html
 

Unregistered guest
Gentlemen,

I would also like to thank all of you for a very interesting thread and a lot of good information.

I hesitated in saying so but I grew up listening to a pair of Altec Valencias using a HK tube amp\receiver my father owned. I now have them in my bedroom, minus the receiver (it died and was thrown out.....Ouch!).

The point of this is that I really appreciate the explanation of the the horn design and its pros and cons. I can attest to how big they are and how heavy they can be.

The TL solution looks interesting if I ever feel a need to add a second sub to my HT (presently using Klipsch R7 series with RSW15), it looks doable even by me.

I do understand what dispersion means and again thank you for explaining what "beaming" is. I guess this partly explains the 60 x 90 Tractrix horn design solution by Klipsch.

Once again, thanks for learning me.

I'm all fer it!
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5852
Registered: May-04


This thread has laid dormant for a while and I would hate to see it go into the past. Here's a bit on a XO design that also covers why flat measured frequency response may not be what you get when the spec shet says that's what the speaker does. I'm not at all pushing this brand of speaker, but I think the article is worth reading.


http://www.aperionaudio.com/media/data/hd-x3_tech.pdf


And for those nights when you just can't sleep, here's a handful of articles to read:


http://www.harman.com/wp/index.jsp?articleId=default


 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5853
Registered: May-04


http://www.directacoustics.com/lexhtml3.htm
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5854
Registered: May-04


http://www.mhsoft.nl/RoomAcoustic.asp

http://www.hometheaterhifi.com/volume_1_1/v1n1spk.html

http://hometheater.about.com/gi/dynamic/offsite.htm?zi=1/XJ&sdn=hometheater&zu=h ttp://www.humanspeakers.com/whatis/PR.htm

http://hometheater.about.com/gi/dynamic/offsite.htm?zi=1/XJ&sdn=hometheater&zu=h ttp://www.soundstage.com/maxdb/maxdb021999.htm



 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 546
Registered: Dec-03
Alternative room acoustics.
http://www.decware.com/paper14.htm
 

Silver Member
Username: Dakulis

Spokane, Washington United States

Post Number: 541
Registered: May-05
Tim,

Any word on T-Man and the Lings? I thought Margie indicated that they would be there last Friday or Saturday. Is T-Man engaged beyond his ability to provide an update or are they still in transit? We're waiting. . .
 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 547
Registered: Dec-03
Tawaun is in Texas and heading home soon. We should see something near the end of the week.
 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 910
Registered: Sep-04
Has anyone heard the remarkable Bolzano Villetri range of speakers? Not cheap of course (£2800 - £21000), but the really interesting thing is the patented design where they fire the tweeters into the main drive units causing massive (360 degrees allegedly) dispersion. I heard and saw them at their European launch last Sunday. Unfortunately, they were using relatively inferior electronics so it was difficult to guage how much fidelity there was there. That said, the soundscape was very uniform wherever we were in the long room so their claims to omni-directionality seemed substantiated. An interesting take on the subject methinks.

http://bolzanovilletri.com/

Regards,
Frank.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5868
Registered: May-04


Oh, those guys from Milan, they're funny fellows!


I guess you've heard these, Frank. I would have to say the literature is writen in a "Bose-ian" fashion that seldom speaks well for the longevity of a company. But the European market is quite different from the American market and Italian products are always aimed at something other than what the American firms such as Wilson are touting.

"Counter-aperture". Now what does that mean? Sealed?

"1) The sound stream is radiated by the loud speakers, 2) a partial interaction caused by the floor and ceiling creates reflective waves to enhance the volume.

3) The sound fields differ in efficiency and dynamism, 4) thus producing only the purist sounds possible."



Yes to the first statement. Yes to the second statement. Probably would have to to the third. And, I would hope so to the last.

 

Silver Member
Username: Timn8ter

Seattle, WA USA

Post Number: 549
Registered: Dec-03
Something interesting that I witnessed recently.
A pair of highly touted and well known floorstanding speakers were sold, used, from a well known Internet website where people sell higher end audio gear. When the buyer received his speakers he discovered they had suffered an enourmous amount of shipping damage. So much so, that his claim to the shipper amounted to thousands of dollars. He then took them to a friend of mine to have them restored. These speakers are perhaps 5 years old. My friend opened them up to discover some interesting things that you would not expect from speakers that sold new for over $6000 per pair. First was the cabinet material. Like many manufacturers the cabinets were made from veneer covered fiberboard, however, I wouldn't call it MDF (medium density fiberboard). They flaked when you picked at it and it wasn't very dense at all. Maybe low density fiberboard would be more accurate. The real surprise was the crossover. It was full of low quality iron core inductors and electrolytic capacitors. Now, I understand there are such things as high quality iron core inductors which are useful when dealing with low frequency drivers needing high values say 5mh or more, but why ALL of the inductors? Besides being electolytic, the caps weren't even good electrolytics. They were huge even though they were low value which means they were loosely wound and not what I would consider audio quality. There was nothing special about the drivers either which were essentially off the shelf and of mediocre quality.
How is it that these well reviewed, highly regarded speakers consisted of about $300 worth of materials?
Is this the same thing that leaves me unimpressed by so many mass-market speakers?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5939
Registered: May-04


While I generally believe you get what you pay for, there is no rule that says paying more will get you the best.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5940
Registered: May-04


http://www.adireaudio.com/Files/TechPapers/GroupDelay.pdf
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 5941
Registered: May-04


http://www.adireaudio.com/Files/TechPapers/WooferSpeed.pdf
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