I didn't always have this problem. Moved into an apartment, then back into house.
One speaker is noticeably quieter, I have to turn balance quarter turn to sound equal. Sound quality is fine.
I have switched cables, channels , it's the speaker. What could be wrong?
One speaker is noticeably quieter, I have to turn balance quarter turn to sound equal. Sound quality is fine.
I have switched cables, channels , it's the speaker. What could be wrong?
I had a similar problem with a pair of speakers.
Turned out the voice coil in one was partially shorted.
The faulty one showed up as lower resistance on multimeter.
Turned out the voice coil in one was partially shorted.
The faulty one showed up as lower resistance on multimeter.
I had a similar problem with my Spectra22. Turned out the bias voltage was low in the speaker with the low volume. This is a common problem with these older speakers as the caps and diodes in the bias power supply age.
I had my tech rebuild the bias supply to bring bias voltage to 6kv and equalize the bias voltage to each speaker. This cured the problem.
Hi,
Swap bias boards to check. If so, replace all failed
components in the duff board in both boards.
rgds, sreten.
Swap bias boards to check. If so, replace all failed
components in the duff board in both boards.
rgds, sreten.
Switch the interfaces, not the bias boards, it will save you quite a bit of time 🙂
If interfaces confirm the panels is at issue, see if all three (or five - is this a spectra?) wires are securely connected into interface connectors.
I have had a couple pairs of Model 3 and 2+2 that the "bundled" stator wires, or "bundled" bias wires became disconnected from the main pin.
I would start there before doing anything else.
I believe Acoustat Answer Man would agree
If interfaces confirm the panels is at issue, see if all three (or five - is this a spectra?) wires are securely connected into interface connectors.
I have had a couple pairs of Model 3 and 2+2 that the "bundled" stator wires, or "bundled" bias wires became disconnected from the main pin.
I would start there before doing anything else.
I believe Acoustat Answer Man would agree
you dont have to measure it. just swap components. i dont know if there is a resistor between the bias and the menbrame? i guess so this resistor will give every now and then as well. witch would make the repair even simpler. bbut rather work top down. so first swap bias or interface. then you klnow witch one is at fault and test further. no need for a probe then.
How do I get in there? Do I just remove all those 8mm looking bolts?
Are there so few parts that it would be simpleset just replace stuff?
Are there so few parts that it would be simpleset just replace stuff?
look at the pic.....Acoustat on the back plate...see pic.... top peace of the bass box....pull that...it called the interface.. ....an you well have 5 wires from the panel. see the other pic..... red ,blue,black,yello,whit....pull them....swap with other side..put the wires back in....if the low out put moves ... to the other panel.... you know interface .....bias maybe.....good luck
Attachments
![Spectra_11_biasfix_01[1].jpg](/community/data/attachments/482/482931-6cae80d7dbec7e6cd6f5cdf4aaec7291.jpg?hash=bK6A19vsfm)
![23257715_2_l[1].jpg](/community/data/attachments/482/482951-633bde083d795b97daeedc60980bd23c.jpg?hash=YzveCD15W5)
![350x700px-LL-d0d87048_image[1].jpg](/community/data/attachments/482/482953-250dc13f8829cb1a9d8e5426f67d739b.jpg?hash=JQ3BP4gpyx)
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Remove the six bolts, turn interface on its side, and remove the wire "bunches" from the three taps (Blue, red, white). Swap with other interface on other speaker. See if low volume problem stays with interface or the panels.
Make sure the interfaces are unplugged, and when removing the middle bias plug (red) touch the other two connections to drain the bias voltage that may be present (you will see/hear a crack)
Post back results.
tyu - he has the 2+2 - only 3 wires on the MK121...correct?
Make sure the interfaces are unplugged, and when removing the middle bias plug (red) touch the other two connections to drain the bias voltage that may be present (you will see/hear a crack)
Post back results.
tyu - he has the 2+2 - only 3 wires on the MK121...correct?
According to schematic I saw, got three wires. Now if I switch boards
And it sounds better, I get that there is something wrong in the board.
But what?
I moved them gently during my move, maybe a wire is loose?
Any possibility it is a bad bias fuse?
It also has monster cable- is it possible the stuff has gone moldy and there is a
Bad connection?
And it sounds better, I get that there is something wrong in the board.
But what?
I moved them gently during my move, maybe a wire is loose?
Any possibility it is a bad bias fuse?
It also has monster cable- is it possible the stuff has gone moldy and there is a
Bad connection?
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Don't switch boards - you will have to desolder the connections...
Just swap the interfaces (the metal box) between speakers and see what you have.
What is your location?
Just swap the interfaces (the metal box) between speakers and see what you have.
What is your location?
Right john.......I gess it was 11 his name..... sorry....
an the same Questions over an over...
search is so ezey for all....theres so much info......on Acoustat 121 interfaces...
I just gooooogel.....vary fast .......but it all good....you got one of these pic...
an the same Questions over an over...
search is so ezey for all....theres so much info......on Acoustat 121 interfaces...
I just gooooogel.....vary fast .......but it all good....you got one of these pic...
Attachments
![427682d1404861109-acoustat-answer-man-here-air[1][1].jpg](/community/data/attachments/483/483410-f81b3ea18d3d239e2e189891482b30b1.jpg?hash=-Bs-oY09I5)
![modC_v2[1].jpg](/community/data/attachments/483/483416-034441492604235ef966e9126e513f18.jpg?hash=A0RBSSYEI1)
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Wrinex......as long as the bias is at 6k.....3ea 9" Acoustat panels will put out.30-35hz ezey
vary hard to get better sound for the money.....lot mods to get even better sound...from these almost 30 years old ESL setups....just got pr of M3....$300 for the pr...comes with the interfaces on the right....I like the biger box....killer setup.....
vary hard to get better sound for the money.....lot mods to get even better sound...from these almost 30 years old ESL setups....just got pr of M3....$300 for the pr...comes with the interfaces on the right....I like the biger box....killer setup.....
Get a Fluke hi voltage probe...
if you are going to own old esl and or work on them get yourself one of these they are inexpensive and work very well for this application. Best regards moray james.
Fluke 80K-40 High Voltage Probe
if you are going to own old esl and or work on them get yourself one of these they are inexpensive and work very well for this application. Best regards moray james.
Fluke 80K-40 High Voltage Probe
Now that we know you have the 2+2, there is no adjustment for the bias voltage like there is on the Spectra series. Most likely you have an issue with the bias system especially if the reduction in volume is equal across the audio band.
First try swapping the interface boxes from one speaker to the other. This will verify that the problem is in the 'black box' and not in the panels or elsewhere in your system.
If so, it's probably best to replace the five ceramic disc capacitors in the bias supply as a first step. These are the most likely parts to fail.
Report back and we'll move on to subsequent steps if that doesn't work.
Also please be patient when waiting for my reply. I have a full time job as well as volunteering about 10 hours a week at the local railway museum, so I'm not exactly hovering over DIY Audio waiting for someone to post. But I do try to check in at least once a week.
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