One thing I would like to suggest is that the balanced outputs be on 
1/4-inch TRS jacks and be resistively balanced, not actively balanced. 
The ring would go to signal ground through an impedance matching the 
output impedance at the tip. A fair number of good designs are using 
this approach. This way, we have 100% balanced/unbalanced compatibility. 
I would propose a TRS jack with a TS-to-RCA adapter for those who want RCA.

While XLR and out-of-polarity signals on pin 2 and pin 3 may be nice, I 
don't think they buy much in this type of an installation, typically 
limited to one control room.

This goes against what I normally suggest, but in this case it makes 
sense in my opinion.



On 2015-04-11 3:53 PM, Corey Bailey wrote:
> Hi Tom,
> Thanks for bringing up this topic as I'm currently designing a
> restoration phono preamp for my own use. I'm doing this simply because
> it's been awhile since I've built anything electronic or done any board
> level work and I feel the need to scratch that itch.
> I'm basically going to build in everything on your wish list except for
> a couple of things:
> Unbalanced (phono) inputs only The only reason I can see for balanced
> inputs is for a line input to the EQ sections (an outboard option I
> already have). Besides, to do this requires more amplifier stages (even
> if unity gain) and I want to keep the active stages to a minimum.
> The outputs will be both balanced and unbalanced.

Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada                             647 479 2800
Quality tape transfers -- even from hard-to-play tapes.