[jandrews]

There's a SET400 for sale on one of the audio market sites.  I have no relation to the seller...just curious about the unit.

It's a SET400 with balanced inputs provided new by AVA.  I'm just curious why this would be requested given that the amp is single ended.
What is happening to the signal after it is inputted into the amp via the XLR connectors?  I'm curious if it would just be the negative and shield being tied together in the amp or is there a transformer used ?

https://www.usaudiomart.com/details/649967136-audio-by-van-alstine-vision-set-400-amplifier-with-xlr/

[I.Greyhound Fan]

There is plenty of gear that is not balanced but have XLR's.  The guy may gear that has only XLR outs.  My BAT preamp only has XLR inputs and outputs.  Much of the Atma-Sphere gear is the same.

[danielgk]

A number of different methods were employed when AVA first started looking into support for XLR.  This took place between late 2016 and early 2021 (if the dates on my files are accurate).  In the end, we decided on the approach that fit in best with the amplifiers we build:  XLR for bridged monoblocks and RCA for single ended stereo.  This connection method results in no "extra circuitry" in the signal path, and no "extra power supplies" required.  In the event that a user wanted to use monoblocks and only had single ended RCA source available, the R2X was created and made available.

Any stereo with XLR inputs, or more likely switchable XLR / RCA, uses op amps, relays, and a plus and minus 15v power supply to accomplish this.


Dan

[jandrews]

Dan,
Thanks so much for the response. That makes sense... I really appreciate hearing directly from designers and engineers as I'm interested in the circuity and problem solving involved.
I'm aware that some people have only balanced outs on their sources and some amps have XLR inputs even though the unit isn't balanced.  I just didn't know that AVA used to offer them on the SET amps.
thanks
JS

[avahifi]

This amplifier would have active internal circuits to convert balanced to single ended operation to run the internal single ended circuits.

We quit doing this because it was too much monkey motion and did not product better results.

Frank