Spectra 11, Where can I find a replacement for the part labeled TTA-ULT3?

Read more on the Acoustat Spectra 11 in our home audio section

Ryan Benitez2012-12-31 05:08

This part that I assume to be the voltage regulator transformer is making an annoying sound that can be slightly muffled by pouring glue on it. Replacing the part would really help the sanity of both myself and my wife. If anyone knows where a replacement can be found I would really appreciate it.



Acoustat Answer Man2013-01-06 17:38

Ryan: Part number TTA-ULT3 is the ultrasonic bias transformer that provides part of the high-voltage step-up necessary for the ESL's operation. As it's name suggests, it operates above typical human hearing so it should NOT be audible. This means that your transformer is either operating below normal frequency for some reason, or it has an odd sub-resonance. I've never encountered this complaint, so I'm poking around in the dark here.

Finding a replacement part may be difficult, as I haven't seen any for sale from any of the sellers who bought the obsolete Acoustat inventory.

You might try installing a locking plastic cable tie around the periphery of the transformer's body. This might squeeze the transformer enough to change its vibrational character. You could also try swapping transformers between speakers (be very careful of the bottom pins on the transformer). If the problem moves to the other speaker, then it is the transformer. If the problem stays on the same speaker, then something in the circuit is causing the transformer to misbehave.

Please let me know your results. I am curious to know the cause of this problem, as I might be able to help other Acoustat owners in the future.

Ryan Benitez2013-01-06 18:01

I measured the voltage with a 1000x probe and got 2.9 volts. I had no complaints about the sound but did the ultrasonic bias upgrade (about $3 in parts from digi-key) and took the transformer off the board that was making sound to pour glue on the bottom side. After the glue dried I reattached the transformer and have not heard the unwanted sound again so far. Also adjusting the voltage on both speakers fixed the 1 dB mismatch between speaker and increased efficiently by about 3 dB.


Acoustat Answer Man2013-01-07 00:39

Great news. The ultrasonic supply can be a little finicky before doing the upgrade, but its operation is very stable after the fix. The real beauty is that the system is both regulated and adjustable. Therefore, the charge can set at a specific point, and once set, it is unaffected by variations in mains voltage.

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