Transformers vs. active for balanced to unbalanced conversion

tenor12

I have a story and a question. Some time back I bought and assembled a VMPS larger subwoofer kit. Since I didn't want to drive the main speakers (Vandersteen 2C) full range, I bought a dbx crossover to split the signal. Imagine my dismay when the thing came bearing only balanced inputs and outputs! I felt pretty dumb. How was I to hook it up? (The only unbalanced alternative, Hsu, was many times more expensive.) I sorted through much contradictory advice and decided that I needed to convert the unbalanced signal to balanced for the crossover, and then back again for the unbalanced power amps. I found a reasonably priced unit called a "Clean Box" that would do the trick in both directions, so I made the necessary cables and hooked the whole thing up. Well, it sounded dreadful. Whereas my system sounded clear and pristine (if slightly bass-deficient) before, now it was slogging through a morass of sonic "goo" (great bass, though!) The day was saved when I discovered upon poking around in back of my NAD preamp the existence of a set of balanced outputs on its backside! Again I felt rather inept for not noticing or remembering this. So I made another set of cables long enough to reach from the preamp to the crossover and hooked it up. The improvement was remarkable, and while it's definitely listenable now, the signal still has to make a single trip through those wretched "Clean Boxes". Consequently they are targeted for replacement.

My question concerns possible replacement units. As far as I can see my options are as follows:
1. Replace with transformers (Radio Design Labs)
2. Replace with an active unit similar to the Clean Box (also RDL) but of much higher quality
3. Replace with an all in one unit by Sonifex (possibly not available in the US, and pricey)
4. Bite the bullet and go for the unbalanced Hsu crossover.

Does anyone out there have any suggestions as to which would be the best-sounding alternative? Any and all advice is welcome. Thanks!

soiset

Resurrection time.

So, what did you learn? I might have suggested a Rane BB 22 between the xover and the sub, but I would have had a much, much better idea: Get a Rane AC22, used, on ebay, for about $60. It is a superior xover, and while the inputs are balanced, the outputs are unbalanced. Problem solved.

ben62670

soiset wrote: »

Resurrection time.

So, what did you learn? I might have suggested a Rane BB 22 between the xover and the sub, but I would have had a much, much better idea: Get a Rane AC22, used, on ebay, for about $60. It is a superior xover, and while the inputs are balanced, the outputs are unbalanced. Problem solved.

I agree. Why the resurrection?

soiset

Just doing a lot of searching around looking to solve an impending HT crisis, trying to get out on the cheap. I think, in the end, I'm going to have to buy two ART T8's to fix my problem properly.

I am about to pick up a Sunfire TG3, which is very much like the Outlaw Audio pre/pros that came out a year later, in 2004 or so. I'm beginning to adopt the super-high end philosophy (but not the finances) that processing should, or at least might as well, occur at the source (the blu-ray player in this case). This leaves me running analog 7.1 from source to pre/pro, then out again.

From the pre/pro, I'd run to Rane THX 22 and 44 eq's, which are rca unbalanced (so I won't use the XLR outs on the Sunfire, darn it), then to four AC22 xovers. These, as I wrote, have balanced in and unbalanced out. This is not a big deal with these low level pieces so long as the cables are kept short. But from there, we go to the amps, which are all balanced. This is where I anticipate trouble (ie hum).

My solution so far, as I said, was to go to multichannel transformer isolators. I haven't seen it written anywhere, but that sure seems to be what ART was thinking when they made 8-channel transformers.

<Spock> What do you think of my solution?

mmadden28

soiset wrote: »

Resurrection time.

So, what did you learn? ...

Were you expecting the original poster to read this? He has 8 posts in over three years and hasn't posted since then either.

unc2701

Three different issues you're talking about here:
Unbalanced to balanced
Ground loop
Long cable runs

For unbalanced to balanced, just hook SE positive output to XLR positive input and SE ground output to XLR input negative & ground (do not do this in the opposite direction, ie tie XLR output ground and negative together).

For ground loop, see:
http://www.passdiy.com/pdf/articles/ground-loops.pdf
and there's probably info on this in your crossover manual and the manual for the ART.

For long SE cable runs, you're basically SOL. Keep the cables away from EMI sources and cross your fingers.

tenor12

Ha! Was I surprised to see replies to this after three years! For anyone who wants to know how this turned out, I replaced the preamp with a Sherwood Newcastle unit, which has bass management provisions built in. Everything sounds great now, especially with a Cornet2 phono stage and a Chime DAC. I couldn't part with the NAD preamp, so it serves upstairs now with a Rotel 980BX, and the old upstairs amp (Yamaha A700), which I also couldn't part with, went to my classroom.