add balanced inputs to power amp bryston or adcom

[MDRuss]

Originally Posted by Jim Williams

That's not a problem with the Adcom 555. Just ground the low side (ring or pin 3) if the driver circuit is transformer coupled or electronically cross coupled outputs. If they are inverter balanced outputs, float pin 3 or the ring. The Adcom's use a 2 wire AC cable so grounding loops are avoided. I've installed Adcoms in many rooms with many consoles and monitor output circuit designs. There is always an easy way to integrate the two.

Jim Williams
Audio Upgrades

Thanks a TON Jim! I've got a GFA555 that I have been getting a bunch of noise through when connected to my Central Station. Took your advice and built a TRS-RCA cable with the ring floated - BAM - problem solved. It's great having guys like you around here!

[Jim Williams]

We aim to please. BTW, there was a guy in Nashville with the same problems, I told him the variables and said he would need to address this at his end. He got all uppity about it and said my attitude was disrespectful. He then declined to have his amp modified saying he had found others and so on.

I guess I didn't hold his hand tightly enough...

[theBF]

Years ago I had contract work with a small low end studio. They had hum in their monitors and asked me to fix it. So when I looked into it they were driving the balanced console monitor bus across the control room into a Yamaha power amp. The console ref. level was +4 dBu and the amp wanted -10 and the amp was unbalanced.

So I put together a pair of Hammond 804s with 14 dB pads on the outputs and connected everything. The engineer ran up the monitor fader to the top and couldn't hear anything! He thought I made a mistake and rolled tape. It almost sliced his ears off!

When I came back the next week they gave me back my transformer rig. They could not get use to monitors that accurately presented the full dynamic range of their electronics. They needed to hear the noise hissing clearly at the bottom to believe things were working. Funny thing was you could clearly hear the tape noise floor on blank tape but dead quiet electronics was clearly unnatural. :-)

Not exactly on topic but this thread reminded me of this incident.

BF