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Boston Acoustic A-60 Series II

 

New member
Username: Jazzlistener100

Post Number: 1
Registered: Jun-11
I scored some A-60 Series II at my local goodwill and got them for 20 bucks! Only problem is that one of the speakers is fully original and working beautifully but the other cabinet is totally wrong. Some one replaced the 8" woofer with a different woofer and it didn't fit so they clued the woofer in and screwed holes in the cabinet to put fasteners down to hold the woofer in place. Well now I need a replacement woofer because this crappy make shift china woofer is not working out for me and the clue stop sealing the cabinet. These Acoustic crossovers deserve better! Does anyone know if Boston Acoustic have replacement woofers in stock? If not, what woofer should I replace it with? Here are Pictures of the crappy cabinet and good one.UploadUpload
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16333
Registered: May-04
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The wonder of this forum is it will run ads right in the middle of a post, making it impossible to read the entire post. If I have this right, you need new woofers for your A60's. Boston hasn't produced those woofers in twenty years. I tried to replace the woofers in my A100's about seventeen years ago and even back then they weren't stocking replacements for their original series of speakers.

Woofers are mated to enclosures mostly by the use of Theill/Small parameters. A woofer that has nearly identical TS parameters to the original A60 driver would replace the existing drivers with more or less the correct numbers. Technically, it would be "in the ballpark". Unfortumately, not many woofers are being sold today which fit correctly into a sealed enclosure and certainly not replacements for the heavily felted cones of the Boston area speaker designs from that generation. Add to that the shallowness of the original BA box and things probably aren't going to mate up exactly or even all that well. You would want to pay particular attention to the Qts of the driver as this will largely determine the tansient capacity of the driver within the volume of the BA enclosure. Obviously, you'll need to know the internal volume of the box before you start calling for replacements. You'll also need to know the filter types and slopes (1st order, 2nd, etc.) used in the orginal design along with the target crossover point to the high frequency driver. The outside dimension of the driver's frame, the total depth of the driver and the mounting hole locations are also good to have ready when you go looking.

I would give BA a call and ask for their assistance either in a new replacement driver that might be suitable for the old box and crossover or for specs to use when locating a different driver from, say, Parts Express or Madisound. Sorry to tell you there isn't much hope of restoring the A60's to their original sound. Those drivers were built by BA to their own specs and even the replacements I purchased for my A100's are not the same sound as the originals. They turned my A100's into something more akin to an A150, a definite step backwards IMO.

I will tell you my A40's have finally been retired. They are no longer competitive with what is available today. New computer aided designs and better materials have made the quality of the BA's a fond memory and not much more. The A40's were the really favored budget speaker from the original BA line but they just don't sound that good nowdays IMO.

Good luck; if you're willing to accept the fact the A60's will never again be what you heard in 1982 and thirty years of design have made them mostly irrelevant, they will make decent remote speakers. Be ready to do some cabinet repair and probably some kludging of the new driver as mounting holes hardly ever line up correctly.



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New member
Username: Jazzlistener100

Post Number: 2
Registered: Jun-11
Thanks for your advice. I'm going to try my best to get a correct replacement. I do agree with you when you say now these days speakers are better design and sound. But I'm only 16 years old and my dads 1960's JBL's sound great. I don't listen to the boom boom pop music I listen to jazz and only jazz. I rather invest in the time and money to have a well operational vintage speaker system because they sound better to my ears. Sucks they don't make stuff as good as back in the day. Thanks for your time. You helped out a lot.
 

Gold Member
Username: Superjazzyjames

Post Number: 1574
Registered: Oct-10
Jazz, sorry about your speaker dilema.

You should look at the thread, "Music selections for the speakers guys". A guy named Art posts a lot of great jazz albums there. He & I are both jazz fans. We like everything from ancient Louis Armstrong stuff of 1917 right up to today!

 

Platinum Member
Username: Plymouth

Canada

Post Number: 16388
Registered: Jan-08
Welcome to eCoustics jazzlistener100!

You can found a woofer there:
http://oaktreeent.com/Boston_Acoustics_Speaker_Parts.htm

You can also replaced both with identical reference here:

http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=489&C FID=31348464&CFTOKEN=43446009
 

Gold Member
Username: Illuminator

USA

Post Number: 5534
Registered: Apr-05
Another way to do it is get the part number from the real woofer and google it. Might find something on ebay etc.

Haha this reminds me of the Mission 731i speakers I purchased a couple of weeks ago.
 

Gold Member
Username: Superjazzyjames

Post Number: 1577
Registered: Oct-10
That's what I thinking Jexx! "Gee this sounds awfully familiar!"
 

New member
Username: Jazzlistener100

Post Number: 3
Registered: Jun-11
I've talken to parts-express.com support and they say replace it with a Dayton Audio 8" classic woofer. This is perfectly equal to the original specifications I got from Boston Acoustics today. But the Magnet oz. is 15? and it's over all weighs 3.5 lbs. Is it true that smaller the Magnet less of the speaker? Is Dayton Audio good stuff?
and if you guys listen to jazz awesome... Today I was listening to Micheal brecker with Ron carter... with my acoustics.. sound great but that replacement woofer doesn't sound as good as the other cabinet.
 

Gold Member
Username: Superjazzyjames

Post Number: 1578
Registered: Oct-10
Yeah, Michael Brecker was great! His final disc, "Pilgrimmage" in of my all time favs!
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16393
Registered: Jan-08
jazzlistener100

If you get the Dayton 8" I suggest you to replace both woofer to have both balanced speakers!

The voice coil diameter is very important, I can see on your above picture that it seem different between the original and the replacement, the magnet can be smaller but strongfull according to its composition!

I like Jazz then a missmatched speaker can make that the music lose any sense!

Those Boston are not the best speaker for listening jazz but for 20$ with the replacement price, that's OK!

Which amplifier drive those speakers?
 

New member
Username: Jazzlistener100

Post Number: 4
Registered: Jun-11
Should I really switch out both woofers. I don't really want to replace a original woofer, Will it sound better if I replace both drivers? and if I replace both drivers, you think Dayton Audio is goon enough quality for the crossovers and tweeters?I want to get the best woofers for my crossovers. and These cabinets are sealed so what makes them really sealed? What do I do to make them just like factory sealed? should I glue them in or use reson?
These speakers play jazz really good. The crossover makes the difference I think. Classical music kicks to. I have a 75 watt per channel KLH stereo receiver that puts out the ok power to the Boston Acoustics but down the road I'm going to get a Yamaha reciever when I save some real money.
Man Micheal Brecker is a beast. I'm guessing you have it but he is on Chick corea Three Quartets Album Amazing Album get it if you don't have it. Do you listen to Big Band Jazz as well? I just saw Gordon Goodwin's Big Phat Band live a couple of months ago. Man Eric Marienthal just whaled that night! I'm actually a Trombonist at my High school. I'm pretty much the only teenager you'll know that listens to this historical music. And if you enjoy sax don't forget Joe Henderon, John Coltrane, Cannonball Adderley, Lester Young, Sonny Rollins, Max Roach, Eric Marienthal, Eric Dolphy, Lee Konitz, Lou Donaldson Just to name a few of the sax players I listen to.
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16395
Registered: Jan-08
jazzlistener100

If you are affraid to replace both woofers, buy one on this link:
http://cgi.ebay.com/Boston-Acoustics-A60-8-copy-woofer-New-Speaker-/150376724311 ?pt=Speakers_Subwoofers&hash=item230326b757

Whitout a test with the Dayton woofer I can't tell you if it sound good, the comments from buyer is not a reference to buy it even if most give 5 stars,most of poeples are not able to hear the difference!

I listened Becker and Big Phat Band on You tube which I did not know
, I admit that they are great musicians!

Sealed>>> without balanced port, you can sealed it with plasticine or urethane foam strip!
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16396
Registered: Jan-08
Original refoamed woofer:
http://cgi.ebay.com/Boston-Acoustics-8-Inch-woofer-refoamed-/360358796672?pt=Vin tage_Electronics_R2&hash=item53e70edd80

A pair of A-60 Serie II:
http://cgi.ebay.com/Boston-Acoustics-A60-Series-II-Home-Stereo-Speakers-/3207186 40748?pt=Speakers_Subwoofers&hash=item4aac52166c
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16334
Registered: May-04
.

"This is perfectly equal to the original specifications I got from Boston Acoustics today."


Which specs are you referring to? Basic specs such as power handling or dimensional specs are not going to tell you about the electrical/mechanical characteristics of the driver. It's quite possible BA doesn't have more detailed specs for the original A60 drivers for several reasons. That, however, shouldn't mean you ignore the specs for a replacement driver as they will determine how well any driver mates to the enclosure. Looking at this woofer; http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-310, the Qtc of the driver is borderline for a sealed enclosure system. That may be as good as you get today as acoustic suspension systems have largely fallen out of favor since the days of home theater's ascendance. For that price the Dayton driver might be a reasonable selection. Yes, since you are not going to be subtituting an equivalent driver in all respects to the woofer in the other cabinet, matching both drivers by way of replacing both drivers is almost mandatory.


"Will it sound better if I replace both drivers? and if I replace both drivers, you think Dayton Audio is goon enough quality for the crossovers and tweeters?I"


It's not that the two drivers will sound "better" but rather they will sound more alike to each other than one Dayton driver would sound to the original BA driver. Consider the different materials used to build the two drivers, no one uses the same materials today as did the builders of the late 1970's when the A60 was created. That alone tells you the Dayton driver and the orignal BA driver will not sound alike. The BA driver was purpose built for a sealed enclosure and conforms to the basic ideas of how to design a woofer for such a system. You'll probably find any replacement driver you buy today will have less apparent mass to the cone itself, the cone will be thinner and lighter and the very soft, pliable suspension system of the original driver will have been replaced by a somewhat more taut suspension. These qualities define the "free air resonance" of a suitable driver for either a sealed or a vented system and determine which enclosure type the woofer would be best suited to mate with. The Dayton is a generic replacement and, as I said, its parameters are somewhat on the borderline for what you might choose if you had more diversity of options. Dayton has become Parts Express' "house brand" driver line. They are the largest retailer for Dayton and tend to resort to Dayton for many recommendations. That doesn't mean the Dayton line is poorly made but just that PE will suggest the Dayton line before anything else and the Dayton line was meant to be interchangeable with lots of drivers rather than purpose built as was the BA woofer.

Then, consider the different surround materials used in the two drivers. The original BA woofer employed a soft foam surround material to join the cone of the driver to the frame of the basket. The "surround" is the convex material on the outer perimeter of the cone itself. The material used and the way it is joined to the cone has a significant effect on the sound of the speaker system as this is where the pressure waves which create sound are being terminated at the driver's edge. By employing a dissimilar material in the Dayton driver (a PVC compound) the Dayton will have a different sound than will the original BA. For this and several other reasons, replacing both drivers becomes almost mandatory. Otherwise, you might as well stick with the mismatch you already have.

A word of caution here, if you decide to buy "original" BA woofers, beware. The foam surrounds on the original Boston area acoustic suspension systems is notorious for drying out and breaking down. Once this occurs the driver must be repaired or else the entire sealed enclosure systems fails. If a driver has not had its surround replaced, then I would be suspect the surround is not going to last once you begin using the driver. If a driver has had its surround replaced, two things might occur. First, the replacement surround might be slightly off center and the driver's performance will suffer to some degree. Second, the surround material might not match the original and the same issues I mentioned above would apply when it comes to the final sound of the system. The slowly self destructing foam surrounds were the cause of many replacements being made with other than orignal spec woofers in numerous acoustic suspension systems over the years.

The magnet structure and weight do play a role in how the driver sounds but you don't have many good options available to you in replacement drivers. If you are going to change that parameter of the driver's operational system, then it is better to go up in weight as opposed to downward as long as the overall depth of the driver still fits within the existing cabinet.

You have mentioned mating the driver to the crossover in several instances. While you don't necessarily want to start replacing each component in the BA system, we once again have two issues to deal with. One, the original crossover components in the BA have certainly drifted away from their original spec after thirty years time and are not making the crossover at exactly the original target frequency at this point. This isn't too serious as the BA crossover was very simple and the drivers were very forgiving. Of course, while you have the driver out of the box, it would be wise to check for any signs of age or abuse which might show up on the crossover board. Look for brown spots on the board under a component or at the edges of the capacitors (the large "can" shaped items in the crossover with leads going to the board). In a crossover the problem areas are; capacitors tend to leak their internal materials (the brown goo you're looking for) and resistors can be burned by too much power and distortion from the amplifier (the brown spots on the board you might find) while the coils of wire called inductors are virtually good forever unless the board shows damage. While a component might be bad without showing any signs of a problem, this is a basic visual test you should do before you invest any more cash in the BA's. Once you get to the point where you would replace both the woofers and the crossovers, then there's no longer any point in trying to salvage a vintage speaker for anything other than nostalgia.

Second; when a designer approaches a blank sheet of paper, the crossover is what is mated to the drivers, not the other way around in most cases. If you've spoken to BA about the A60 drivers, I'll assume they've provided you with the data which would be needed to then replace the drivers with acceptable units.




"These cabinets are sealed so what makes them really sealed? What do I do to make them just like factory sealed? should I glue them in or use reson?"


DO NOT glue the drivers into the cabinet. There will come a day when you might want to get back into the cabinet and glue will only mean the destruction of the woofer and the enclosure when that day comes. Probably, the driver you purchase will come with a thin gasket to attach to the mounting surface of the driver/enclosure rabbet. Ask whether this is included with the driver whenever you make a purchase. This sort of seal is very important in a sealed enclosure but not so much in a vented system, so make sure you're being supplied an appropriate material or order them when you buy the woofers. If push comes to shove, you might have a suitable gasket still on the orignal driver or you can use a very - very! - thin roll of Mortite around the frame of the driver. (Google Mortite and you'll find information and a source. Whoever sells you the driver will also probably have a source for gaskets.) Use just enough gasket material to make a good, air tight seal and not so much it makes it difficult to get back into the cabinet. When installing the replacement drivers, do not over tighten the screws or you will strip the threads in the thin particle board cabinet - then you are screwed.



What makes a sealed enclosure a sealed enclosure? That would depend on which end of the lens you're looking through. In its most basic function, a sealed system is one that is sealed from air leaks. A small air leak in a sealed system will create problems so gaskets and enclosure integrity are of a primary importance. By sealing the rear wave of the driver in the cabinet rather than allowing the rear wave to escape as would be the case in a vented or ported system (your dad's JBL's), the low frequency response of the system gains several advantages and takes on several disadvantages.

Acoustic suspension systems - sealed enclosures - are meant to emulate infinite baffle systems. In other words, an infinite baffle would be larger in any dimension than the length of the soundwave which represents the lowest - longest - frequency produced by the driver. If the speaker system can reproduce a frequency of 40Hz, then you need a baffle which is wider in every dimension than the length of a 40Hz wave which would be approx. 20'. Before even your dad's 1960's JBL's were designed, people often placed low frequency drivers inside closets, in fireplaces or in the floor/ceiling of a room and made certain the surfaces were sealed from air leaks in order to create a baffle which wouldn't allow a low frequency wave to wrap around it. When the acoustic suspension speaker system was created in the early 1950's, it allowed a change from the huge horn loaded speakers such as a Klipschorn or a large JBL/Altec if the listener wanted low frequency response. By only using the frontwave of the driver (while the rear wave is absorbed inside the enclosure by stuffing material) the sealed box allows for a more gradual roll out of low frequency response than would a vented system which allows the rear wave to exit the box and create null points in the frequency response of the system. The most significant trade off for this sort of bass response is the loss of additional reinforcement to the system's volume potential. A disadvantage of sealed boxes (those using only the frontwave of the driver) is they require higher wattage to drive them to similar output levels than do vented systems of most sorts. Should you compare the BA's to the JBL's, this will become quite apparent. Due to the extended bass response of the system acoustic suspension speakers also require somewhat more care in their placement within a room than do most vented systems. Support structures for sealed boxes also need to be more substantial as a rule since the deeper bass will mean more rigidity asists the speaker. Don't place your speakers on open boxes or boxes formed by other cabinets or you will excite the resonance of that box.

Sealed systems can be somewhat altered in response chatacteristics by adding or removing the internal stuffing material. I hestitate to suggest you deviate too much from the original BA concept but a new driver might need slightly less stuffing inside the box than did the originals. There is a technically correct amount of stuffing for each driver/box system but you have no way to determine where that point exists. However, if you buy other than original BA drivers, you might want to first listen to the system as it stands with the drivers in place. Then remove a small amount - a few handfuls at most - of the stuffing material from inside the box and listen again. Take away no more than 1/3 the original amount as you listen for favorable changes in sound quality. If you cannot hear any changes as you alter the amount of stuffing, return to the original amounts and leave it be. Do not drastically alter the location of the stuffing material inside the enclosure. And be certain you haven't glued the drivers in place or you won't be able to perform this experiment.


https://www.ecoustics.com/electronics/forum/home-audio/683535.html


https://www.ecoustics.com/electronics/forum/home-audio/676769.html


http://search.yahoo.com/search?ei=utf-8&fr=slv8-hptb5&p=define%20acoustic%20susp ension%20speaker%20system&type=


http://www.madisound.com/

http://www.planet10-hifi.com/






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Gold Member
Username: Superjazzyjames

Post Number: 1579
Registered: Oct-10
Jazz, if we're going to discuss jazz further, we should do so in the "Music selections..." thread and reserve this thread for your woofer situation. You have a lot of advice to read and consider right here and now. Replacing both woofers, once you find a suitable replacement would be my advice. You will probably want to keep the sound consistant between the 2 speakers, right?


I like most of the artists you mentioned as does Art. Max Roach was a drummer. I don't recall him ever playing sax.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16336
Registered: May-04
.

Sorry, after looking at that last post again, I realize I hit a wrong key which might cause some confusion should you speak to other retailers about replacement drivers. This sentence; "Looking at this woofer; http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-310, the Qtc of the driver is borderline for a sealed enclosure system", is wrong. The value for the driver itself should be stated as "Qts" and not as "Qtc". Qts is the data for the driver itself outside of a box or off a baffle. The proper Qts for a woofer in a sealed enclosure system should fall at .35-.40 or higher. When the driver is mounted in an enclosure or placed on an infinite baffle, the value of the system (the total "Q" of the system) is then expressed as "system Qtc" or possibly shortened to just "Q". System "Q" and "Qtc" are interchangeable and mean essentially the same thing should you see references to both values when dicussing complete speaker systems.

The Qts of the driver will ultimately determine the "Q" of the system in a sealed enclosure and, in this case when you use a driver with a Qts of .4, the system Q(tc) will tend to be somewhat overdamped. Bass extension should be adequate though bass volume may be somewhat truncated when compared to the original BA woofer. If the speakers are going to be placed close to a wall or corner, this might work out OK. Since you cannot change the box size itself, toying wih the amount of internal stuffing might provide the type of sound you're looking for. You might even want to order a small package of polyfill when you order the drivers and try increasing the total volume of stuffing by no more than 20% over the original BA design. Though it might seem counterintuitive, adding stuffing material to the enclosure makes for what appears to be a larger internal volume as far as the woofer is concerned. Again, add small amounts at any one time and do not excede 20% more material or 30% less.


If you haven't yet decided to order the Dayton driver from PE, discuss with whomever sells you the drivers what they might suggest as regards stuffing material in the BA boxes. Know the internal volume of the BA enclosure before you make any calls. You can determine this by simply measuring the external dimensions of the box and subtracting from each dimension twice the thickness of the front baffle (which you can easily measure with one driver removed or by taking a look at the cutout for the speaker connections). http://www.ehow.com/how_2320295_volume-cubic-feet.html

My guess would be you are most likely to prefer a system Q of approximately .8 or slightly higher. This is a very "sellable" number in a speaker and tends to sound good with most music. As you get below that point, the bass tightens but also looses some of its "flavor" for most listeners. As you get above that point, bass can tend to sound sloppy and particularly so when the speakers are mounted near walls, floors or corners.

http://www.danmarx.org/audioinnovation/theories.html


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New member
Username: Jazzlistener100

Post Number: 5
Registered: Jun-11
Hey Thanks for all the info. A little over bearing because it's my first time. I'm planning on replacing both woofers. I'm planning on ordering the dayton audio 8" woofers. but before i do. What would be the ideal woofer replacement for such a sealed cabinet. Just realized that dayton woofer is border lining badly. Is there any woofers out there that will work well in this sealed cabinet. I asked a local shop if they have any woofers in stock that will work and they said they don't because all there 8" woofers won't fit because BA cabinets are non-standard size. Is that true? and if that is true then what happens if my replacement woofer don't fit. should I make an adapter for the replacement woofer so they can fit and seal correctly? I'm planning on playing jazz and classical through these speakers so what do you guys think i should do? one way or an other I need to get rid oh that non-original woofer... it doesn't belong in that cabinet. Any suggestions with help me dearly. Oh when i asked BA support for specifications they sent me this saying this is the only thing they have.... The cabinet size is Height=18.25" Width=11.25" length= 7.25" if that helps. thanks for all help.
Specifications:

Frequency Response 52-20,000 Hz

Nominal Impedance 8 Ohms

Sensitivity 1 watt (2.83V) @ 1m 90 dB

Woofer 8"

Tweeter 1"

Crossover Frequency 3,000 Hz

Recommended Amplifier Power 10-75 watts (per channel)
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16402
Registered: Jan-08
jazzlistener100

Why not simply choose the original refoamed woofer on E-Bay!

Jan with his usual romance blinded you with so much useless infos for a simple woofer replacement!

If you like the original sound replace it by the original!
 

Gold Member
Username: Superjazzyjames

Post Number: 1582
Registered: Oct-10
Plym, please don't start something here with Jan. I think his point is that the original woofer is no longer being made. Buying used audio gear or parts on ebay is rather risky. Also, I must say Jan's advice here is sound, although it may include more details than Jazz actually needs. Too much detail is better than too little. Jazz can always focus on the info he needs and go accordingly.


 

Platinum Member
Username: Plymouth

Canada

Post Number: 16404
Registered: Jan-08
Super

There is none problem to replace a woofer refoamed, for the old one you only put WD-40 on the foam surround to rehydrated this one, we can see the difference of frame basket and magnet between the picture of the original on Ebay and the dayton, is the coil is the same diameter?.

The best advice is new speaker(not woofer) but to ravive those one to the original sound I suggest the used woofer!
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16340
Registered: May-04
.

P, you find Qtc and Qts to be romantic?!

Really?!!!



You must be the thrill on Valentine's Day!






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Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16341
Registered: May-04
.

"I asked a local shop if they have any woofers in stock that will work and they said they don't because all there 8" woofers won't fit because BA cabinets are non-standard size. Is that true?"


Sounds like they were either playing dumb or they were blowing off a sixteen year old kid who might ask too many questions about a $29 woofer. There is no such thing as a "non-standard size" speaker enclosure. The bottom line is how much internal volume is within the enclosure no matter the shape of the enclosure itself. A cabinet can be wedge or circular in shape and be a better cabinet in many ways that the conventional rectangular box as neither the wedge nor the circle have parallel surfaces to amplify resonances. Before home theater came along and speakers moved into the "family room", speakers were wider than they were deep. That worked rather well for ... oh, ... 70 years or so.

Boston had a concept for their orignal speakers which harkened back to those days of infinite baffles built into walls. A wide front baffle will support the low frequency extension of the high frequency driver better then would a narrow front baffle. There will also be less "baffle step compensation" when a shallow cabinet is placed close to a wall. The ideas BA brought to the market in their first series of speakers were exceptionally innovative yet based in solid science. Add to that the heritage of the men who founded BA and their ties to the most successful and innovative speaker companies in America for several decades starting with the introductiion of the first acoustic suspension speaker in the early 1950's.

Don't go back to that shop, they are not worth your time.


" ... and if that is true then what happens if my replacement woofer don't fit. should I make an adapter for the replacement woofer so they can fit and seal correctly?"


No, because then you're right back to where you started with a woofer held in by fender screws. The point of the information I've given you is for you to learn something about how speakers operate. You don't do that by whacking together some jerry-rigged job that neither looks right nor sounds right. What you need to do is find a woofer that is as close to correct as possible.


"What would be the ideal woofer replacement for such a sealed cabinet. Just realized that dayton woofer is border lining badly."


It's really not that bad. You have to go back to my first post in this thread and reconsider this, "Sorry to tell you there isn't much hope of restoring the A60's to their original sound." You are very likely not going to find a perfect replacement for the original woofers, as a matter of fact, you don't really know the one woofer that appears to be OEM hasn't had its surround refoamed and that it too is not absolutely original. You are working with several "unknowns" and trying to make the most of as many "knowns" as you can find.


one way or an other I need to get rid oh that non-original woofer... it doesn't belong in that cabinet."


Now you're sounding like another sixteen year old we have on this forum. You're getting anxious and you've only been at this for two days. Slow down and consider your options, you have working speakers and nothing needs to change tomorrow or even next week. When I rebuilt a fifty year old amplifier I waited four months for a $2 part to become available. People fly across continents to find the right part for old cars. Don't worry and don't rush. Things will come together and there's no need to rush them and end up making a mistake. Take time to learn from this experience.



I'm not in the habit of providing specific suggestions which say "go buy this". I tend to do even less of it when the question requires I do all the leg work for someone who should be learning how to do this on their own. You've been provided several suggestions for where and how to find drivers. You've also been given what I think are fairly good pros and cons for each selection. You need to weigh your options and make a few calls. You'll get more opinions, some will be worthwhile and some will be as useless as the guys that told you about "non standard size enclosures". The BA cabinets are shallow, that's what you need to keep in mind when ordering a woofer. The woofer must not be deeper than the allowable dimensions you have to work with. Period!

Otherwise, the values you need to work with are fairly basic. First, know the target Qts of the driver - it should be 0.40 or higher, which doesn't rule out the Dayton unit. When you are working with a sealed system and you place a woofer into the volume of a specific enclosure, the Qtc of the system is derived. The Qtc of the system will be higher than the Qts of the raw driver outside of an enclosure. (Calm down, P, I'm not trying to romance anyone.) You're not building a speaker system from scratch so those are numbers which are somewhat flexible as a target. One of the best things about working with sealed enclosures as a first experiment in speaker construction is the stuffing can change the system Q. More or less stuffing will arrive at the numbers you need for a proper system and many designers still rely on a method of adding and removing stuffing to get the sound they desire. So don't stress over this, it will work out.

You'll have the volume of the enclosure once you work out the numbers as I've described above. Anyone you call should be able to determine which woofers would then be a good match to the enclosure by doing a little math and not just going immediately to a Dayton woofer. And, in the long run, you might still end up with the Dayton woofer as the best choice.

The specs BA provided you are pretty basic, which is understandable since the T/S parameters which derive the Qts and Qtc values (and others) didn't really become popular with designers until later. However, the numbers to look at in their specs would be the "sensitivity" which is stated as 90dB for the entire speaker system. Not just the woofer but the entire system. That means - using a common assumption - the woofer is going to have to be at or near that 90dB target. Anything more than +/- 3dB away from 90dB will alter the balance of the system.


The nominal impedance of the system is stated as 8 Ohms. Using that same assumption mentioned earlier, find an 8 Ohm woofer. Avoid a 4 Ohm woofer. Normally, the impedance of the driver is stated on the back of the magnet assembly. If you can pull out the apparent OEM driver from the one cabinet, check what impedance is claimed and use that as your baseline.

The crossover frequency is stated as 3,000Hz for the system. The crossover frequency is actually where both drivers are down -3dB and in combination make for flat response. You need to find a woofer with response out to slightly above 3kHz. The Dayton woofer doesn't have really helpful specs in this area but they claim response to 3kHz. That might mean the driver is down in level at 3kHz or it might not. No one at PE will probably be able to tell you - and they'll then just say it will work - so you might want to contact Dayton themself for this information. Typically, BA allowed their woofer's mechanical roll off to take down the level of the driver above the crossover point so don't go looking for a driver with response out to 6kHz unless it fits all other parameters.

Those are the basic electrical parameters you'll need to shoot for. The mechanical values of distance between screw holes and the actual physical dimension of the frame of the driver will be important as you don't want to booger up the cabinet by having a driver that just doesn't fit the hole. Keep in mind the actual depth of the driver and how much depth you actually have inside the cabinet.

Then you start calling around. There aren't that many retailers of new drivers to worry about.

Drivers suited to a sealed enclosure are not as common as they were two decades ago so you will have a limited selection to choose from. None will be a perfect match to the original woofer. But you can make any driver with "near enough" numbers work by toying with the amount of stuffing inside the enclosure.


Now, if all of that is more than you care to deal with, then you can buy the woofer P has suggested. Refoaming a woofer isn't rocket science. The larger the driver, the more liekly it is to be slightly off when the new surround is in place but you have to take your chances with refurbished equipment and understand any return policies available. You'll know a bad woofer as soon as you hook it up and turn up the volume, it will have a scraping sound and at that point you shut everything down and return that driver. Is a new surround going to create a speaker that sounds just like the original? Probably not, but it will certainly be close enough for someone who has never heard an original A60. "Sorry to tell you there isn't much hope of restoring the A60's to their original sound."

What you're aiming for is a pair of speakers which sound very much like the original or possibly even a bit better due to newer technologies and materials. You can make a wide variety of drivers work in the enclosure if you have numbers which are close to what was originally in there. Since you don't really know whether the one driver is OEM - and it probably isn't since most woofers would have needed repairs by this time - make the best of a learning situation. Collect your options, weigh them all together and make an informed decision. It ain't life and death and not even rock and roll from what you say.

You can do this and it will be just fine in the end.




.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16342
Registered: May-04
.

I would be wary of eBay. Know who you are buying from, find their reputation on the service and get clear agreements about returning equipment.
 

New member
Username: Jazzlistener100

Post Number: 6
Registered: Jun-11
Thanks guys. I know I can be annoying because from my inexperience and my age. sorry, I'm learning. I'm going to wait till I find a original woofer that I can replace it with. A replacement that I know is original and not damaged at all. I rather wait for the original woofer to appear on the internet then throw some new drivers in. Thanks for you time. But I got more than enough information on to make an decision.
Sincerely jazzlistener100
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16405
Registered: Jan-08
Jan Vigne
Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16340
Registered: May-04

Posted on Sunday, June 26, 2011 - 11:09 am:
.

P, you find Qtc and Qts to be romantic?!

Really?!!!



You must be the thrill on Valentine's Day!

Jan

Between us, this is only a woofer replacement nothing more, Jazz do not have the knowledge and equipments to replace the woofer by a Dayton which will for sure need a crossover correction!

Chance for him, a woofer is available on Ebay for his A-60 serie II, I thing that the good thing to do is buy this one and put it in his speaker!

Simple and easy!

No?
 

Gold Member
Username: Superjazzyjames

Post Number: 1585
Registered: Oct-10
Jazz, I don't think anyone is annoyed by you. None of us knew these things at your age. You have a great head start by getting into it here & now.

Plym, Jazz may find the original woofer on ebay in good condition, but the odds are not the best. Again, please stop with Jan. Let's not have another thread turn ugly ok? I mean no matter how you slice it, no matter who starts what, the potential is there. So, let's just keep this one civil and focus on helping Jazz. Thank you.

 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16343
Registered: May-04
.

"Jan

Between us, this is only a woofer replacement nothing more ... "



P, I have no idea what is between "us". This is what the op chooses it to be. Either way, he now has some knowledge that he didn't possess before this thread began. He can now make a more eductaed decision as opposed to someone simply providing a link to eBay. That alone was worth the time.

No?



.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16344
Registered: May-04
.

"I'm going to wait till I find a original woofer that I can replace it with. A replacement that I know is original and not damaged at all. I rather wait for the original woofer to appear on the internet then throw some new drivers in."


Keep in mind the woofer changed between the orignal A60 and the A60II. There might still be a part number on the one woofer which you can use as a reference. Manufacturers also altered their designs with slight modifications during the run of a model. As long as you are sure you're buying a woofer that would have been in an A60II, you should be OK.

.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16345
Registered: May-04
.

"Jazz do not have the knowledge and equipments to replace the woofer by a Dayton which will for sure need a crossover correction!"


A crossover correction? Of what sort? What makes you so convinced the Dayton driver wouldn't operate well with the OEM crossover? What spec indicates that to be true?


.
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16408
Registered: Jan-08
JV
"A crossover correction? Of what sort? What makes you so convinced the Dayton driver wouldn't operate well with the OEM crossover? What spec indicates that to be true? "

Do you know if only the Voice coil is the same size?

The dayton is a paper cone then the Jazz original woofer has a polymer cone, how that can sound identical?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16349
Registered: May-04
.

Well, the diameter and length of the voice coil wouldn't require a crossover change. Why do you think it might?

Treated paper vs a polymer wouldn't necessitate a crossover change either, not just by virtue of two different materials being used in two different drivers. The two materials might not sound identical throughout their range to someone with a fairly critical ear for such differences. But that has nothing to do with the low pass frequency at which the woofer would cross to the high frequency driver. The crossover will deal with frequency only in this speaker (and possibly a slight trimming to the sensitivity of the tweeter - but we don't know for a fact that any trimming is required for the A60). There would have been no "corrections" for any character differences and, indeed, there are no corrections I'm aware which directly address the character of a treated paper driver. This was, at the time, a budget speaker. The crossover would have dealt only with filter order at the desired frequencies and possibly a slight lowering of level should the tweeter require such - a single resistor. The shallow cabinet of the BA line at this time meant the speaker was intended for placement close to a wall so there wouldn't even be a baffle step compensation circuit in this crossover. None the less, had a BSC circuit been included in the design - for some reason - it would still only be a notch filter dealing with frequency, not character.

What sort of crossover "correction" would "fix" the difference between the sound of treated paper vs the sound of a polymer woofer if both drivers had similar upper frequency response where the crossover is important?


I'm not seeing a justification for a crossover "correction" in either of your statements, P. Enlighten me. Which crossover components would you change and why?




.
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16410
Registered: Jan-08
Jan

You are good for writing but on the ground you need to learn!

If you can't heard the difference between 2 voice coil size then a paper cone and a polymer, you need to visit a loudspeaker fabricant!

Many thing can modified the sound, 2 different form of basket will not have the same sound, the size and the length of the voice coil, larger will tend to sound louder with less mid in the woofer case, paper and polymer cone and the depth make a difference which will not fit well with the tweeter., the magnet power and the thickness, the cone thickness etc. ...

There is so many thing which can modified the sound!


"Which crossover components would you change and why? "

Here I made a sound test with a sound generator and a db meter then I modify it in regard with the result to keep a flat frequencies response!
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16350
Registered: May-04
.

You are the one who needs to both learn and read information presented to you, P. The size of the voice coil will not by necessity alter the frequency response of the driver. Certainly the vc size is not going to alter anything pertinent to the crossover frequency. If you feel it should, then locate and bring us proofs which can demonstrate such alterations would occur based solely on the vc size. Make these proofs relevant to a sealed enclosure speaker system.


You are saying "modify" the sound, not change the frequency response in any way which would necessitate a crossover "correction". Basic crossover design (the type found in a BA A60) does not take into account the character of a polymer woofer vs a treated paper driver, they are simply filters which roll in or out the action of the drivers at a specified frequency point. Don't try to pull this one over on me, P. And don't try to imply there is something here that doesn't exist.


"Here I made a sound test with a sound generator and a db meter then I modify it in regard with the result to keep a flat frequencies response!"


So you don't know what would change because you don't know of any specific differences between the response of a treated paper driver and the response of a polymer driver, right? Try this, a designer does not select a driver and then go about correcting its response when they could have chosen a different driver altogether. In other words, a designer doesn't choose a specific polymer or paper driver and then set about making the extremely small notch filters which would be required to addess the results of your "sound test". Look at the response measurements of any well regarded speaker, the designer has not made an attempt to completely "flatten" the response. Suggesting that is what the op would be required to do in order to replace a woofer is beyond ridiculous. No, the
designer choses the driver for its overall character in the first place and doesn't concern themself with the very small deviations which make up "character".

Would then the op need to make such corrections? No, because that isn't his intent, he is not designing a speaker from the ground up. He's simply replacing a woofer with another woofer. The T/S values I've mentioned are those that are important to him and not the "character" of the materials. He already understands he is not going to find a perfect match nor would he know what a perfect match is since he has never heard an original A60.

It's well known in the speaker industry that any two identical drivers - one serial number apart - will have slightly dissimilar frequency response and T/S parameters. Any designer seriously into high end speaker design will measure the individual drivers they have to work with or a small group of drivers to ensure "regularity" in manufacturing before they begin a project. They are checking mostly for the T/S parameters as they are what the designer works through, not the 0.25dB variations in the frequency response of the raw driver. The "flatness" of frequency response at the crossover point has nothing to do with the basic design of a speaker system, what matters are the T/S parameters which do not mention "flatness" of frequency response. What you are suggesting would mean each driver employed by any serious speaker manufacturer would require time consuming and expensive testing to flatten out the very small irregularities which exist between two identical drivers before you would find it acceptable. Get real, P! That might work for a builder who is looking for two speakers for themself but not for any industry beyind that small amount. And, even for the small diy builder, what you are suggesting - adding multiple components to the crossover - would be an exercise in futility and self defeat.


The Boston A60II was a budget speaker which sold for a few hundred dollars per pair. It was meant to be partnered with decent (for the time) receivers; Yamaha, Denon, Luxman, etc. with a handful of watts. Slamming a few dozen additional components into the crossover would have made for a very difficult load on those receivers, no budget oriented speaker designer would do that. Doing the sort of manipulation of response - assuming it was possible to change the character of a driver - would have been far more than the budget allowed for the A60. The crossover in these speakers is very simple, almost to the point of having not much more than a cap and a resistor hanging on the tweeter. The A60 crossover doesn't perform any task other than filtering the upper and lower frequency roll out/in of the two drivers.

Don't try to make this into some esoteric exercise just to justify your incorrect statement regarding "crossover correction" when that's all the A60 was about. You're showing you really don't know very much about loudspeakers.



.
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16412
Registered: Jan-08
All I can tell is LOL!

I did not expect better from you!

Even if I am right you still argue!

I have to modify one ton of speakers then I know what i'm talking about, let your keyboard and your searching on googly then play on the ground then come back whitout nonsense answers!

End of discussion!
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16351
Registered: May-04
.

Tell me this, P, what is it that gives a treated paper, a polymer or a metal driver its unique characteristc "sound"? If all of those drivers had identical frequency response, you would still have the "character" of the materials to deal with. What is the "character" of the material?

The resonant response of paper is not identical to the resonant response of a polymer. Polymer will have different break up modes within the driver's surface than will, say, aluminum. These are not gross abberations away from flat response but just the characteristics of the materials being employed when they are put in motion. Most of these resonances and distortions are designed to occur at the limits of the driver's capacity - "out of band" some would say. One material will have very small abberations in one frequency band while the other will have its resonant signature in a different band, that is the perceived value of the different materials to a designer and why they select one rather than another.

This is what we hear when we say we can detect the "sound" of a polymer driver or a metal dome tweeter. With that fact in mind, how would you go about dampening those small bands of resonance which may not amount to more than a few hundredths of a dB without also dampening the frequency band which is reproducing the musical signal? How would you address material "distortions" or break up in the crossover? What would you do? Which components would you use and in what configuartion would you use them to address this issue of driver resonance and break up? What would your "cure" do to the music? What would the additional crossover components do to the load on the amplifier?




.
 

Platinum Member
Username: Plymouth

Canada

Post Number: 16413
Registered: Jan-08
Since I can't win with you because you are always right by diverting the discussion!

For the last time>>>>End of discussion!

Have a good day!
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16352
Registered: May-04
.

"Diverting the discussion"?!!!







P, if you don't have answers, then just say you have no answers to the very clear and pertinent questions I've asked of you. Don't dance around and don't try to insult me.



P, you're something else. Not sure what, but you're definitely something else.


See you in the funny papers.


.
 

New member
Username: Misterfun_54

Post Number: 1
Registered: Apr-12
I realize this is an old thread but Jazz, did you ever get a replacement woofer? I, too, am in need of some help and am not willing to pay (if even still available) more for just the woofers than what the units cost originally.

This turned into such a pi$$ing match between JV and Plym. I dare not ask about the history between these two.
 

New member
Username: Misterfun_54

Post Number: 2
Registered: Apr-12
and for the record, if Jazzlist's A60's are like mine, the cutout diameter is 8 inches, requiring a nominal 9 inch woofer. Even the biggest 8" that PE and most other suppliers offers has an OD of ~225 cm (8.85"), leaving the bolt(screw) hole circle at ~ 8.2", barely enough wood to secure the woofer.
e.g.:
http://www.parts-express.com/pdf/295-356s.pdf
http://www.mcmelectronics.com/product/MCM-AUDIO-SELECT-55-1550-/55-1550
http://www.madisoundspeakerstore.com/approx-8-woofers/sb-acoustics-sb23nrxs45-8- 8-woofer/
(OK, you could angle the screws in, but really, would you?) AND to JV's (long-winded but informative) point, would they sound any good?

the replacements from BA are $200+ : http://www.bostonacoustics.com/Discontinued-Product-Info-C100.aspx
is this the kind of $$ you want to spend on a mediocre speaker?

final comments:
to JV: perhaps the repair shop was right, saying they had no replacements.
to Plym: at a minimum of $100 for woofers alone, your suggestion to not throw good $$ after bad and just buy a new system has merit.
toJL: My resolution was to rabbet a half-inch groove around the cutout, allowing me to drop in a 10" woofer to suit the box size and put them in the garage where the listening is "less than critical".










}
 

New member
Username: Jazzlistener100

Post Number: 8
Registered: Jun-11
Sorry to post so late, I ended up getting the original speaker replacement of ebay which worked great. The replacement sounds great, wish I had a really decent receiver/amp to back up these BA's but for now they sound fine, better than that dam chinese replacement that was in the box in the first place. I'm in the market for a receiver to back up these BA's, think a old sansui,sony,kenwood, or pioneer should do the trick. I'm hopefully thinking on making makeshift little vinyl jazz station out of the BA A60II with a old receiver and a good old turnable, yes the BA's aren't the usual vinyl pumping speaker but they'll get the job done.
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