RE: I think I can help here....

OTL Asylum

OTL, Output Transformerless Amplifier User Group.

Posted by Atmer (A) on July 11, 2021 at 08:15:57

In Reply to: I think I can help here.... posted by Lew on July 6, 2021 at 09:05:40:

Hi Lew,

Good to see your post and thanks for giving the background on how the AU90 transformer came to be used in SoundLab ESLs.

Unfortunately the archives were not carried over to the new SLOG site. Site owner Mark Gilmore indicated when the the new site came into being that he would try and attempt to port the archives over but up to this point that has not happened. There recently has been renewed discussion about the AU90's and it would be great if you could post your response over on SLOG to give the newer members historical context.

BTW, I have lately been in contact with Rob Mackinlay of ER Audio about his 1:90 audio transformers compared to the AU90s previously supplied, his response was:

"The 1:90 xfmrs on our website are electrically much the same as the ones we supplied previously to the SL Owners group. Externally they look different as they don't have the connector block across the top and the plastic mounting flanges but essentially they are the same. We use two of these in our ESL IV full range ESL wired parallel series to give a turns ratio of 1:180. In this speaker they are mounted on a "drop through" board, much like the output transformer on a tube amp, so the original mounting hardware is not required.

If they are used in a Sound Lab speaker, mounting brackets would need to be added."

So effectively a suitable equivalent transformer is still available for those interested in modifying their SoundLabs.

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Follow Ups Full Thread

Topic - Atma Question - Alsatian 08:59:43 04/14/21 (14)

RE: The impedance does not have to be flat. - Ralph 10:50:08 04/14/21 (13)

RE: The impedance does not have to be flat. - Simon Templar 23:43:09 04/30/21 (10)

RE: I'd use a set of Zeros - Ralph 09:51:59 05/03/21 (9)

RE: I'd use a set of Zeros - Simon Templar 14:34:44 05/04/21 (8)

RE: MA-1s are fine on Sound Labs. - Ralph 10:22:01 05/05/21 (7)

Fairly certain that mine predate that modification.... - Simon Templar 11:02:01 05/06/21 (6)

RE: older Sound Labs - Ralph 11:49:47 05/06/21 (5)

RE: older Sound Labs - Simon Templar 01:04:05 06/08/21 (4)

I think I can help here.... - Lew 09:05:40 07/06/21 (2)

RE: I think I can help here.... - Atmer 08:15:57 07/11/21 (1)

Just noticed this post, November 14. - Lew 10:41:31 11/14/21 (0)

RE: older Sound Labs - Ralph 09:17:20 06/08/21 (0)

Thanks Ralph... - Alsatian 11:07:45 04/15/21 (1)

RE: A lot of the LS35/a variants are 15-16 ohms. Get one of those and it will all be good nt - Ralph 12:08:13 04/15/21 (0)

Follow Ups

RE: I think I can help here.... - Atmer 08:15:57 07/11/21 (1)

Just noticed this post, November 14. - Lew 10:41:31 11/14/21 (0)

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