[dcheming]

Well I'm looking for a high quality method to convert my soundcard's balanced output to SE. Most of what I have found online are the crappy in-line style converter transformers, but I already have some of these that I got from Guitar Center and they sound horrible. I can't afford to go with something nice like Lundahl transformers right now. So this pretty much leaves the active chip-based method.

Can anyone recommend a suitable circuit? Needless to say, I'm not too thrilled about having to insert another device into the signal path, so it must be as transparent as possible.

Do you guys think that the total cost of such a circuit and the quiet PS for it would put it in the range of some good transformers ~$150? Which method would be more transparent? Other suggestions are welcome. Thanks!

 

[threepointone]

I did a LOT of research on balanced rigs, and I must have looked through at least ten different circuits for doing it. Unfortunately, I haven't really saved any of those links; I do remember there was a paper by Rane posted on headwize, with, iirc, some stuff on interconnecting balanced/unbalanced systems

>> edit
ah, here we go:
http://sound.westhost.com/project51.htm

look for the balanced line receiver schematic. esp considers high-end opamps to be in the audio voodoo realm, but if you don't, just swap it with your favorite opamp. if you desire, you can probably get rid of a couple of those filters, too, since you don't really need them for shorter runs and it should be less "stuff" in your audio path

 

[dcheming]

Thanks threepointone, I appreciate the link. Did you ever end up building a circuit that you liked?

 

[Garbz]

I tried an opamp solution with OPA627s, then I went to the DRV134 which also worked ok, but it muddies the bass a bit probably something to do with phase problems. The long discussions I've had on this topic should be searchable on this forum.

In the end I just gave up dropped $150 on a set of Cinemag transformers and haven't been happier

http://www.garbz.com/blog/projects/dibox.html

 

[dcheming]

Thanks for the post. I want to do this right the first time and it seems like high quality transformers are the way to go: no power supply, no op-amp rolling, no precision matching of resistors, etc. I always favor passive components if possible anyways. I'm going to start checking out the prices of the different manufacturers. Are there any other brands that you would recommend checking out?

 

[Garbz]

Jensen being one of the best for transfromers, and naturally one of the worst for price

, I did not look around that much but suffice to say building an audio transformer is not an easy task so something good will definitely make a difference.

 

[dcheming]

I know these are super cheap, but do you think they would be okay to get me by for now?
http://www.edcorusa.com/transformers/wsm/wsm600-10k.htm

These seem very versatile and the price is pretty good:
http://www.edcorusa.com/classx/matching/ex/ex101.htm


Or do you think I should just plan on spending over $150 to get good quality? Thanks for your input.

 

[Rescue Toaster]

I've heard the XSM 10k:10k from edcor can do a decent phase split when you keep the drive impedance low. They're $12 ea too.

The best phase splitter in the world is the lundahl 1676 wired as 1:0.5 + 0.5. $105 ea.

There isn't much middle ground. Hardly makes sense to spend $150 on something that still has flaws when the best is $200.

 

[siriuz]

How should the XSM10k/10k be wired, as a phase splitter?

 

[Rescue Toaster]

Drive the full primary and run the secondary center tap to ground. That way you get 2 : 1 + 1. Yeah you lose some gain but it should give the best result.