I have a pair of what I believe to be Acoustat 1+1 with mk-131-b interface. I have had these for decades and they have been in storage for 10 years. They have a very low output. How do I go about rebuilding them? The boxes are riveted so I haven't even been inside them for an inspection. Which rivets do I drill to at least open the case? Am I about to get in over my head? I have repair experience, just not on this type of speaker. Am I wasting my time?
Thx,
Don
Thx,
Don
I've never seen an interface that was secured with rivets. I think you are looking at button-head allen screws, removable with the appropriate allen hex wrench. You are not wasting your time. Speakers must be plugged in for at least a few minutes for bias to fully charge. For speakers stored that long, allow days of being energized before making any decisions as to performance. Likely you'll need to replace the diodes and capacitors in the high voltage bias multiplier.
BTW, the MK131 is a limited frequency-range system, designed to be used with a companion woofer. So don't expect a lot of bass from the ESL panels. And don't drive them too hard in an attempt to get more volume if the bias supply is not working properly - you can damage the audio transformer.
BTW, the MK131 is a limited frequency-range system, designed to be used with a companion woofer. So don't expect a lot of bass from the ESL panels. And don't drive them too hard in an attempt to get more volume if the bias supply is not working properly - you can damage the audio transformer.
Thanks for the info. An Allen wrench will be used. There is a dust dirt build up in the buttons so the actual Allen screws were not visible. I was aware of the low frequency limitations and I do have the matching dual coil sub woofer that needs work but that I have done that type of work before. Are there any pictures, videos, or written instructions on the rebuild process available?
Thanks again for your help.
Don
Thanks again for your help.
Don
Since you have low output, I would suggest you start with a rebuild of the bias multiplier. See attached.