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Speaker match for old NAD receiver

 

New member
Username: Subiedriver

Post Number: 5
Registered: Apr-05
I have a 13-yr-old NAD 7225PE receiver (25 watts) to use in an office system. Would like to buy a pair of modestly priced bookshelf speakers to go with the receiver. Mostly quiet listening, lots of vinyl, classical and jazz, solo instruments or small combo (eg Segovia, Django and Stephane).
Was thinking of Epos ELS-3 because of good reviews but open to other ideas. Monitor Audio? Triangle Titus?
Any advice appreciated.

 

Silver Member
Username: Edster922

Abubala, Ababala The Occupation

Post Number: 631
Registered: Mar-05
For your musical tastes (similar to mine), the Ascend CBM-170s would do nicely, google them for a whole slew of overwhelmingly rave reviews. A real bargain at $340/pair shipped, easily surpassing speakers up to $1000/pair.

I have the Ascend 340s with a vintage NAD amp and pre-amp, and the sound is just gorgeous.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3849
Registered: May-04


I believe the Ascends are a rear ported design. This could be problematic if you want to place the speakers close to a wall. Might I suggest:

http://www.nsmaudio.com/

I think the 5S is an excellent bargain and is easy to place since it's a sealed box. The bass alignment also has a more gradual roll off than a ported design. This will give you deeper bass response for a comparable enclosure size.

I believe both companies offer 30 day trials.


(Check the clearance pages of NSM.)




 

Barnacle
Unregistered guest
I'd like to hear those NSM but they are 85dB in efficiency that is not likely a good match with a 25 watt amp.
 

Gold Member
Username: Rick_b

New York USA

Post Number: 1145
Registered: Dec-03
I drive a pair of 84dB Spendor's with a 20 watt tube amp, in an 18'x18' room with 12' vaulted ceilings. I listen at levels most sane people do, and have never clipped the amp.
 

Silver Member
Username: Artk

Albany, Oregon USA

Post Number: 542
Registered: Feb-05
Rick - I think the key there is that you drive your speakers with a "20 watt tube amp". Most folks who are underpowered try to drive inefficient speakers with low current low power amp. Even though the NAD may have more grunt than a mass market amp it still will not compare to your tube amp. That said, I believe for an office system your receiver will provide enough power for you to choose whatever speaker you want Hubert. Epos, MA, and Triangle are all speakers with great reps with good reason.
 

Gold Member
Username: Rick_b

New York USA

Post Number: 1146
Registered: Dec-03
Art,

I agree. I was just trying to point out that you can't just look at the power ratings and get all the facts. Thanks for the clarification. Cheers!
 

Silver Member
Username: Artk

Albany, Oregon USA

Post Number: 545
Registered: Feb-05
Tubes and Spendors, sounds heavenly. I was just in Portland Saturday at Stereotypes and I listened to Spendors with a fantastic Magnum Dynalab receiver. Wow! I love the Spendor sound!
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3858
Registered: May-04


I agree with Rick on this issue. First, the NSM has a 30 day trial, if you want to hear them you only have to call. Second, third and fourth ... The NAD is not the typical twenty five watt amp. You said this was an office; how loud do you want it to play?

http://www.myhometheater.homestead.com/splcalculator.html]

As you can see, with just the twenty five watts the NAD can certainly produce, you can achieve a volume potential somewhere between very loud and painfully loud. That should be sufficient for most folks.

Like Rick I run tubes with a pair of LS3/5a speakers. It is a small (4 1/2" woofer) 84dB speaker with a 15 Ohm impedance accomplished through a very complex X-over and I have sufficient volume in my 15' X 21' X 9' room. The NSM have a very constant 8 Ohm impedance and a simple X-over. They play quite loudly in my room also. Actually noticeably louder than the 3/5a's, though either speaker can satisfy my volume requirements. The NSM's do some things the Rogers monitors don't do and vice versa. Similar to Rick's Spendors, both the 3/5a and the NSM are acoustic suspension designs which I prefer. It's up to you. I give the NSM 5S a strong recommendation. I picked up my pair on a clearance for $280 for the pair. I can't find the flaw that is supposedly in the cabinet.






 

Silver Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 621
Registered: Feb-04
I'm not sure about that calculator. Says 126.3 dB for me and I've never done that! I suppose dynamics are hard to measure on a Radio Shack SPL meter, and it's not that precise anyway...
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3861
Registered: May-04

Since permanent hearing damage can occur at 126db, I would hope you haven't reached those levels.

The calculator is not mine so I can only point you to its location. The numbers are fairly constant though, therefore anyone can take the specs on their equipment and work out the details on a piece of paper. Every time you double the power from the 1 watt base measurement you will gain 3dB. The second speaker in a pair will bring the system gain up another 3dB and every time you double the distance from the one meter spec for sensitivity you will loose approximately 6dB.

The numbers are only meant for an indication of what to expect from a system. There are many variables the calculator does not address that can affect the overall SPL that can be achieved in a given room with any amplifier/speaker combination. Too many to even address here. Most of all it amounts to what does the listener consider loud. I sold and delivered a pair of Klipsch Cornwalls (104dB @1 watt) with a 150 watt McIntosh amp and the customer opened the windows and went across the street to check whether it would be loud enough for him. (It was.) On the other hand, my opinion was the Cornwall was loud enough when nothing was playing. (The LaScalla was the much better design.)

The real point of my post was to try the speakers before deciding out of hand they would not work. Any amp/speaker combination that can get SPL into the 90dB+ range will make you raise your voice to speak. Any system that can push the SPL to 100dB+ will have you shouting. For most people that's loud enough.

Finally, I wouldn't take the Radio Shack meter as the last word in SPL measurements. It is a rather inexpensive instrument best suited to constant level measurements, not dynamics. The weighting systems are also going to change the measurements you see on the meter. The calculator is giving raw numbers for an unweighted measurement.




 

Silver Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 624
Registered: Feb-04
Jan,

Yeah, the calculator adds a lot of dB for corner loading, and I suppose my speakers are meant to be corner-loaded so I should redo without that and would likely get better numbers. I suppose anything above 115 dB is likely correct.

The Klipsch Cornwall is rated at 101 dB/1W/1m and both my La Scala and Klipschorns are rated at 104 dB/1W/1m. Needless to say, it's typical to listen to music at less than 1W per channel and movies at -20dB on the dial are loud (close to reference levels).
 

New member
Username: Subiedriver

Post Number: 6
Registered: Apr-05
Thanks to all for the recommendations. I'm listening in an office at very quiet levels and so I'm not worried about max volume or "slam." In fact I'm trying to find a speaker that sounds good at low volume, without being pushed hard. I will check out the speakers you all mentioned. Thanks again.
 

Silver Member
Username: Diablo

Fylde Coast, England

Post Number: 104
Registered: Dec-04
There are few speakers which will sound really good at very quiet levels. This is not due to the speakers - it is due to the sensitivety of the human ear. See these charts, which show how the lower frequencies become inaudible when the volume is turned down.

The ideal speaker for these environments would have a big dip in response between 500-5000 Hz! This would bring sub-500Hz sounds back to normal levels.

You won't find many speakers like that, so auditioning speakers with various levels of bass control settings on the NAD will be needed to get the best balance. :-)

 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3869
Registered: May-04


I have to disagree with diablo. Obviously the Fletcher-Munson curves are an indisputable fact of life, but that is not the issue here. No one designs a speaker for only low level listening by incorporating the loudness curves in their design. This is a continuously variable curve which changes as the volume level changes. The only way to design a speaker with "loudness" built in would be to assume one constant volume level since the speaker's EQ would be different once that level was altered.

When someone asks for a speaker that sounds good at low volume, what they are asking for is a speaker that doesn't require being driven by high wattage to sound good. This goes to the simplicity of the speaker and the X-over employed in the design. The more complex the X-over, the more energy is required to drive the speaker. At low volume (i.e. low power levels) the X-over will waste most of that power by conversion to heat. Most speakers on the market today are well beneath the 10% efficiency level of power in to SPL out. As an example, speakers such as the Theils which use complex frequency shaping X-overs normally don't sound as good at low volume as a speaker with a simple X-over.

I would suggest the best route for finding a speaker that sounds good at low volumes is to begin by avoiding any design that utilizes more than a handful of components in the X-over.




 

New member
Username: Subiedriver

Post Number: 7
Registered: Apr-05
Jan, IANAE (I am not an engineer) but your theory makes sense to me. Could you recommend some monitor speakers that have simple x-overs?

I just read some good things about B&W 705s but they appear to need lots of power. Is that because of the x-over design?

 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3877
Registered: May-04


I don't know the current B&W line well enough to tell you anything about their X-over designs. And there are simply too many decent speakers to know who does what. Some manufacturers will point to the simplicity of their X-overs and others will hardly mention the X-over. About the best overall advice I can give is to pay attention to the amount of information given in the specs and advertising. A 1st order X-over is normally less complex than a fourth order design. But since a 1st order design has very shallow filters (6dB per octave) the stress this design places on the driver quality is more than the steeper filters (4th order = 24dB per octave). Some manufacturers will take the 1st order design and do frequency shaping to match the drivers more evenly.

Look through the manufacturer's information and any available reviews to find as much information about the speaker as possible. Then ignore most of it. Don't shy away from higher order X-overs as they may still work well in the hands of a talented designer. (One of my favorite speakers utilizes a first order low pass with a fourth order high pass design.) Consider the amount of variation in the speaker's overall impedance and find a speaker that is fairly constant in the load it shows the amplifier and you are probably on the right track. There are too many items to point to and say this can mean this and that can mean something different. Don't get too wrapped up in the spec sheet. As I stated on another thread, about the only things that spec sheets will tell you for certain are the dimensions, the weight and the finish of the speaker. After that it really comes down to listening to decide what you prefer.




 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3878
Registered: May-04


To explain a bit more about the X-over design, let me give more complete examples. A 1st order design is -6dB per octave. That means a woofer crossed over to a tweeter at 2500Hz will still have a woofer that is fairly active at 5,000Hz and a tweeter which is asked to perform down to 1250Hz. Those are frequencies where distortion and inaccuracies can set in very quickly. It is much easier to mechanically roll off the woofer so the filter is steeper but the tweeter will still be asked to do very low frequencies for a 1" driver.

On the other hand a 4th order design with -24dB per octave will cross at 2500Hz and have the woofer completely out of the picture by about 3300Hz and the tweeter at roughly 2kHz. That places less strain on the drivers but can introduce other problems.

I wish I could make this simpler, but speaker design in particular is always a trade off. As I always told my clients, when I give you one advantage, I will probably add two disadvantages.

It really does come down to listening. There is no substitute for deciding what is important to you personally.




 

Silver Member
Username: Diablo

Fylde Coast, England

Post Number: 105
Registered: Dec-04
J Vigne - I have to disagree with diablo. Obviously the Fletcher-Munson curves are an indisputable fact of life, but that is not the issue here.
The Fletcher-Munson curves are exactly the issue here. Listening at "very quiet levels" does require that the tone controls are used in order to maintain a realistic representation of the original sound. It would therefore be a good idea if Hubert listened to various speakers on his system with various levels of bass adjustment. Where is middle C? 262 Hz? That's the core of most music and which is severely diminished at low volumes.

J Vigne - When someone asks for a speaker that sounds good at low volume, what they are asking for is a speaker that doesn't require being driven by high wattage to sound good
I'm not sure that I understand what you are saying here. If I went into a hi-fi shop and had my intentions confused in this fashion, then I would probably go somewhere else.

I cannot disagree with your theories about crossovers,but I do not see what they have to do with Hubert's requirements. He wants to have the music playing at low levels whilst still being able to answer the phone. Poor efficiency speakers with a 2 watt amp will provide this, regardless of crossover power drain. Only the pre-amp tone controls can provide suficient correction to remedy the missing (vital) mid frequencies.

I agree with your recommendation for infinite baffle speakers for this situation though. :-)
 

New member
Username: Subiedriver

Post Number: 8
Registered: Apr-05
Guys,
What are "infinite baffle" speakers?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3880
Registered: May-04


diablo - I have no idea what your experience with consumer audio constitutes, so please do not take any of my comments as condescending. As with most things audio there are (at least) two opinions regarding loudness compensation.

The purist who wants a system with nothing, or at least as little as possible, between the source and the speakers will opt for a system with no loudness compensation. There are plenty of examples of listeners without the ability to adjust for the F-M curves who are perfectly happy with their systems at low volumes. I happen to be one of those listeners. Other than a 35 year old HK receiver used in a back room, my systems do not have the ability to adjust for loudness and I listen predominantly at lower volume levels.

Why am I happy with the results? Two reasons in my mind. First, the music is more dynamic without the additional circuits in the system. Second, because music is by nature a dynamic entity the F-M curves are seldom correct for ever changing music material. You have to remember the F-M curves are for steady state signals, not the dynamic level changes that occur in music. Therefore, if I adjust the loudness compensation for an average listening level then any pianissimo or forte pasage will be incorrect. So why bother to attempt this adjustment in the first place?

On the other hand there are components which utilize loudness compensation which is at least somewhat useful. Tone controls as a rule do not make the adjustements need to accurately compensate for the F-M curves as the action of the tone control is to broad. In other words, tone controls have the "knee" of their affect at higher and lower frequencies than what is prescribed by the F-M curves. Therefore, adjusting loudness compensation with a typical tone control will still be incorect as too much area is altered to do the job properly.

The "correct" way to adjust loudness compensation is to use a continuously variable loudness control. Several manufacturers have used this concept over the years, the best known to me are the Yamaha and the Mcintosh systems. Both suggested setting the volume control at a typical loud listening level and then adjusting the actual loudness with the loudness compensation control. This control slid the amount of compensation to match the average level of loudness you desired and thus became the volume control you used on a regular basis.

Both the Yamaha and the McIntosh controls also adjusted both the high and low frequencies whreas most loudness compensation systems only boost the bass. This has been another area of choice for the determined listener as to which is truly correct; both ends or just the bass. As you can see from your charts, there is another slight dip in the high frequencies when using the F-M curves. But unlike the low frequency compensation, the upper frequencies do not make a smooth curve; so what is the best way to compensate for that action?

It should be clear that just pushing a button to boost the bass is not the answer and neither is turning the bass and treble control. Therfore, many listeners have decided to eliminate the function instead of using something that was more often wrong than right.

Most certainly, building a loudspeaker with compensation for only one volume level is not the solution.




 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3884
Registered: May-04


An infinite baffle design is what your father or grandfather might have used to get bass extension from the speakers in his system. By determining the bass cut off frequency, you can determine the legnth of the longest soundwave the driver will produce.

http://www.maximacar.com/system_design2.htm

If the baffle the driver is mounted on is larger in every direction than that wavelegnth, the rear wave of the speaker cannot wrap around the baffle to cause cancellation of the front wave. The only sound you will hear are signals which are in phase with each other. Unfortunately trying to reach 30Hz would require a baffle 40' in every direction.

Therefore, people would mount drivers in walls, ceilings, floors, closets and fireplaces. Anywhere the rear wave would be minimized or hopefully eliminated. These systems generally fall into the category of infinite baffle design. This is best described as a system where the rear wave from the backward motion of the driver is not used as a contribution to, or cancellation of, the front wave.

In order to allow small cabinets with some flexibility in placement, E. Vilchur and H. Kloss designed the first acoustic suspension system in the 1950's. Their work at Acoustic Research (AR) was taken from concepts that were established, as are many things audio, from principles that were worked out in the 1930's.

By placing the low frequency driver in a sealed box, the rear wave cannot cancel the front wave of the driver. So, though a true infinite baffle in concept only, the acoustic suspension speaker fell into the same design category.

Any infinite baffle will have a -6dB roll off while a vented enclosure will have the steeper -12dB roll off. In the vented design the rear wave is allowed to exit the enclosure and is used to reinforce the driver's front wave. The main problem with this system is the rear wave will only be totally in phase with the front wave at one frequency. Above and below that one frequency, everything is progressively out of phase until audible cancelation sets in. Both design systems have advantages and disadvantages as do all things in audio.

https://www.ecoustics.com/electronics/forum/home-audio/56618.html

http://harada-sound.com/sound/handbook/defa-d.html







 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3887
Registered: May-04


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

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

http://white.hometheatertalk.com/tips/ib.htm

 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3888
Registered: May-04


Sorry, I've given you the wrong information. I constantly make this mistake, it seems to be one of those brain phart things.

A sealed box speaker will have a minus 12dB per octave roll off and the vented box will have a minus 24dB roll off. Hope that doesn't confuse anyone.


 

Silver Member
Username: Edster922

Abubala, Ababala The Occupation

Post Number: 635
Registered: Mar-05
Hubert,

you might also want to contact David Fabrikant at Ascend, he designed the CBM-170s and I remember him addressing someone else's post asking about the same nearfield-low-volume application as you. He'll also tell you the recommended clearance to a rear wall, I believe it's around 6 inches or so.
 

Silver Member
Username: Thx_3417

Bournemouth, Dorset United Kingdom

Post Number: 194
Registered: May-05
Read 98% of this the part about X-over units, interesting though I do strange experiments every day though it's an on going practice it's a question of science gentlemen.

A crossover be it passive or an electronic active X-over with fixed or variable X-over slopes 6db 12db 18db or 24db octave types it is just something to please the listener, though in life there is no crossover, if you have spot on hearing left and right of your auditory hearing then if you where to take ear plugs and fit them into your ears what you hear will hear will sound muffled.

Like playing around with an active X-over and turning off the HF and all the dialogue coming from the loudspeaker sounding muffled due to just the LF low frequencies playing as a result been reduced, and limiting the dynamic range of hearing.

 

Silver Member
Username: Diablo

Fylde Coast, England

Post Number: 106
Registered: Dec-04
Hubert,
Sorry if I baffled you.

Jan,
Thanks for your courteous reply to my earlier post. I did not find it condescending. However, I found it much more informative than your previous post though -- much nearer your usual high standards -- and with some good links posted later.

I used to be a bit of a hi-fi nut, about 30 years ago. Built amplifiers and speakers. Rebuilt a Quad 22/II system. Mainly bought stuff since then, due to having more money and less free time.
I recall seeing the continuously variable loudness control s on the Yamahas, but hadn't heard of their use in McIntosh pre-amps. McIntosh amps are fairly rare on this side of the Atlantic.

My most used system, at the present time, is a NAD T753 with Castle speakers. 90% of my listening is with the 'tone defeat' switch set. The tone settings (usually 7dB bass / 4 dB treble) are normally used only with 'high-drama' movies (I don't have -- or want -- a sub).

When I am 'deliberately' listening to music, the flat tone settings work well. I use volume settings which are close to natural with acoustic material -- folk, string quartets, jazz. Slightly less than realistic volumes for orchestras and much less than concert level for rock music. This all sounds fine to me.

At some other times, I have music (mainly classical) as a low level background. I leave the settings flat. This is also fine -- for my purposes. It does not intrude into my consciousness much, just provides musical wallpaper. If, however, I switch the tone control on, the music becomes much more 'alive' -- I keep noticing it, which is a problem if I'm trying to concentrate on something else.


It may be a good idea if Hubert ignores the tone controls if it is in his interests to be productive in the office. All depends on whether the music or the work is more important.:-)

That said, it is certainly possible to adjust to low level listening without bass emphasis. I have found that many pieces of music can sound remarkably good when listening on very inferior equipment. I have a portable FM radio in my bathroom which has delighted me often, despite having a mono 3 inch speaker!

Regards,
diablo

p.s. When composing this post, I originally had a page or two of technical stuff, but removed it, in order to make the point more clearly. But I can post it if anyone wants the details. :-)
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3893
Registered: May-04


Go ahead and post the information. It's always good to see what others find useful. There's the opportunity to learn something new.
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