1 plus 1-S, Various, woofer problems

Read more on the Acoustat 1 plus 1-S in our home audio section

Paul Nasso2004-02-23 22:21

I believe I have one of the rare Acoustat MK 131 (1+1S). However, the woofer is shot. The cone surround on the woofer has decayed and the woofer is useless. I guess I don\'t have a question as much as a statement - From your web site I gather that we (owners) are on our own when it comes to fixing our woofer problems. If I am wrong, please correct my understanding, but I think we (us owners) need to find a solution on our own.

This is really a message to identify my self as one of the \' rare owners\'. I would be willing to participate in a helpful manner, but I am just an owner - not an engineer. If you have some advice, I would appreciate it. If you would like more information about my setup, please don\'t hesitate to ask. Thank you for your consideration.

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Andy Szabo2004-02-23 22:21

Yes, the Model 1+1 ”S” was a rare beast indeed: not too many of them were sold. Acoustat ESL\'s are very reliable and long-lived, but the models with woofers suffer the same fate as all speakers that use a foam surround for the drivers: dry rot.

There are three options to repair your speaker:

1. Replace the woofer system entirely with a new subwoofer.
2. Repair the original woofer, or
3. Replace the woofer.

The first option is no doubt the most expensive, but will probably yield the best performance. The woofer system in the Model 1+1 ”S” was not equal in quality to the ESL, and there are many subwoofer systems on the market that I\'m sure could do a better job. Make sure you get one that has a variable crossover frequency that goes up to 150 Hz or higher (level and phase controls would be helpful, too).

The second option is to attempt to replace the surround on the woofer. I say ”attempt”, because I have never done this, and it sounds like a tricky process. I\'ve located a company called Parts Express, which specializes in all kinds of neat audio stuff. See www.partsexpress.com. They have a kit #260-925 that might work. For only twenty-three dollars (per pair), it might be worth a try. Your woofer is already no good, so there is no concern of making it worse!

The third option may be the best, if you can find the right woofer. The Parts Express catalog lists over fifty 10” woofers, from no less than eighteen different manufacturers from across the US, Europe, and Asia. Sadly, only two of those woofers are listed as having dual-voice coils. While I\'m sure this is not a complete list of what is available on the market, it\'s pretty clear that 10” dual-voice coil woofers are not very common.

Furthermore, I am not certain that either of these two woofers is the right choice. They are as follows:

Manufacturer & p/n - Goldwood GW410D
Parts Express p/n - 290-362
Imp. - 8-ohm
Price (USD)- $20

Manufacturer & p/n - Jensen KS210
Parts Express p/n - 293-406
Imp. - 4-ohm
Price (USD)- $80

I don\'t recall the impedance of the original woofer. If it is not marked, you can measure one of the voice coils with an ohmmeter. If it measures about 3-ohms, it is a 4-ohm woofer. If it measures about 6-ohms, it is an 8-ohm woofer. The impedance is important because the crossover values are chosen to suit the woofer impedance. If you use a replacement woofer with a different impedance, the crossover point will change.

If the original woofer is 4-ohms, the Jensen would probably be a good choice. Eighty dollars is what you might expect to pay for a decent woofer.

If the original woofer is 8-ohm, I am less positive about the Goldwood. Twenty dollars doesn\'t seem like enough for a woofer equal to the quality of the Acoustat. At 10 pounds for the Jensen, and only 4 pounds for the Goldwood, there is obviously a difference in build quality and magnet weight. But, on the other hand, twenty bucks is not much of a gamble if you want to give it a try.

The Parts Express catalog does list all the Thiele-Small parameters for both woofers, so if you know someone who knows what to do with those numbers, that could offer some additional guidance in choosing. (I used to be handy with Thiele-Small calculations, but alas, all of that knowledge and documentation has been lost over the years.)

If you have success with any of the ideas listed above, please let us know. Many of the woofers used by Acoustat are starting to fail, and other owners could benefit from your experience.

NOTE: all of the above also applies to the woofer used in the Model One. The same 10” dual-voice coil woofer was used in both models.

Mike Savuto2004-02-23 22:21

Paul, I think you will find that Rockford can be of some help here. My understanding is that they can still provide some repair assistance of the Acoustat products, but you will have to contact them directly. Unfortunately I don\'t have the phone number, but they are listed and I believe you can find the number at another location in the Acoustat section of this website. You might also post a question about this on http://www.audioasylum.com/forums/MUG/bbs.html as well.

Best of Luck, Mike Savuto

Keith Snyder2005-04-30 01:42

Perhaps, I\'m a bit dated with my response to the issue of the deteriorating foam surround. I\'ve included a link to a company that supplies repair kits. I have used the kit with great success and my woofer is as new almost 2 years after the repair. The instructions are clear and simple. At a cost of about $20, its definately worth a try. http://www.speakerworks.net/kits.html

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