Looking for a pair of 1+1 interfaces

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Hoping someone can help me. I've got a pair of Acoustat 1+1s that I purchased a while ago and the guy who sold them to me didn't know that he had the ones that are rolled off at 100hz for use with a subwoofer.

I'd like to get these to be full range, as my old ones were. Do I need completely different interfaces, or can something just be changed in the circuit to get them to play full range, like swapping resistors and capacitors?

If not, is there anyone out here who has a pair of the correct interfaces they would like to sell or can tell me how to rebuild mine so they will be full range?

Thank you all very much in advance for your help!
 
Hoping someone can help me. I've got a pair of Acoustat 1+1s that I purchased a while ago and the guy who sold them to me didn't know that he had the ones that are rolled off at 100hz for use with a subwoofer.

I'd like to get these to be full range, as my old ones were. Do I need completely different interfaces, or can something just be changed in the circuit to get them to play full range, like swapping resistors and capacitors?

If not, is there anyone out here who has a pair of the correct interfaces they would like to sell or can tell me how to rebuild mine so they will be full range?

Thank you all very much in advance for your help!

It sounds like you have what is properly known as the Model 1+1S with MK-131 interface. The 'S' stands for 'with subwoofer', which you may or may not have.

Unfortunately, the MK-131 interface is not capable of full range operation and cannot be converted to do so. What you need is the MK-121 interface, with the internal bass transformer set to the RED position (it's user-adjustable).

Be aware that the MK-121 interface was manufactured for many years and in three different case style. Unless you're prepared for a lot of metal fabrication, be sure the MK-121 you buy is the same shape as your MK-131 (roughly a cube enclosure), so that it will be a drop-in replacement.

Since the 1+1 has limited bass response even with the MK-121 interface, an alternative may be to keep the MK-131 and add one or two powered subwoofers to the system.
 
It sounds like you have what is properly known as the Model 1+1S with MK-131 interface. The 'S' stands for 'with subwoofer', which you may or may not have.

Unfortunately, the MK-131 interface is not capable of full range operation and cannot be converted to do so. What you need is the MK-121 interface, with the internal bass transformer set to the RED position (it's user-adjustable).

Be aware that the MK-121 interface was manufactured for many years and in three different case style. Unless you're prepared for a lot of metal fabrication, be sure the MK-121 you buy is the same shape as your MK-131 (roughly a cube enclosure), so that it will be a drop-in replacement.

Since the 1+1 has limited bass response even with the MK-121 interface, an alternative may be to keep the MK-131 and add one or two powered subwoofers to the system.

Sounds good, where would you suggest setting the crossover and slope in a situation like this?
 
Sounds good, where would you suggest setting the crossover and slope in a situation like this?

I'm not sure at what frequency the MK-131 rolls off...probably in the range of 100-150 Hz. In most cases, the steepest slope is better to minimize the high frequencies coming from the woofer.

In any case, quite a bit of experimentation will be necessary to get the woofer(s) to integrate properly with the ESL. Unless, of course, you get one of the really high-end woofer systems that have built-in room analyzers that do all the hard work for you.
 
Hello Tonepub,

I just acquired a second pair of 1+1's and will consider a 2+2 construction project if I can sell my extra 121-B interfaces.
And FYI IMHO if you have a good room, bass response with 1+1's is fabulous, no sub needed.
If you are feeling the 121-B interface love, make me a fair offer and I will seriously consider selling them to you, I support the acoustat family.
Message me if you like,
Spiegs

PS are you sure you have 1+1's? they should be 7'10" tall.
 
I also have the "Cube" 121 with Red Medallion Interface from a 1+1....let me know if you are interested.

I also have the passive Acoustat Sub that came with a Model 1...forgot I had it...

Note to Tonepub: the "Red Medallion" MK121 interfaces offered by john65b are the latest-and-greatest versions that were manufactured by Acoustat. The 'Medallion' part of the description indicates the use of much-improved audio step-up transformers, and the 'Red' indicates the application of the desirable 'C-Modification' which improves high frequency performance.
 
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