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Balanced vs standard power

Searching for an Isolation Transformer 10 or 15kva. I have the budget for Equitech but I'm sold only on the benefits of isolation and not "yet" on the benefits of balanced power unless one is recording live musicians. My rationale is that most if not all audio components are not designed with balanced power so they may be optimal performers with standard power and lesser performers with balanced power. Until someone does a side by side comparing isolated balanced to isolated standard power we may never know.

I have read the various threads regarding isolation transformers from Equitech 10wq, MGE Topaz etc, and the Euqitech stereophile review. For larger non-balanced options there is Ultra K 600 with K factor correction and triple shielding from the Controlled Power Company. They range from 5 to 25 kva.

I think supersizing Isolation transformers for audio is not well recognized yet because no one has done the necessary review/ comparisons to determine the performance curve of Isolation Transformer size to Audio Performance. Although Isoclean advocates the use of two of their Isolation Transformers for each piece of equipment. Maybe they're trying to tell us something or just sell more transformers. 10 KVA is "plenty" for my system according to Martin at Equitech, but "plenty" is not quantified enough to convince me, so I 'm leaning toward the 15kva on the Ultra K 600 from Controlled Power about $4000 vs Equitech 15 kVA at upwards of $14000.
natan6355

Showing 8 responses by dan_ed

dan_ed
2,451 posts
 
I'm interested in balanced power, and I have a question I hope you guys might now. I have two amps that I like to run together, but the hum like crazy when both are plugged. I know the issue is because one, or both, are not wired in common mode.

I have been reading some papers on the Equitech web site about this issue and they claim balanced power will solve this problem with no equipment changes needed. Not that I dispute their claim, but I'm having a hard time understanding how it would clean up the ground circuit after current has entered from down stream. What do you guys think? Would balanced power connections safely isolate these amps?
dan_ed
2,451 posts
 
I think I get it, but see what you guys think about this. My two amps hum because they reference ground at a slightly different potential, and that creates a small current between them when they are on the same circuit. The balanced connections assure that all components plugged into it reference the same ground so there would be no potential between the amps.

Yes? No? Smoking crack? :-)
dan_ed
2,451 posts
 
Jea48, I run them from the same wall outlet. So I have 2, really three with the SS bass amp, grounded devices on the same circuit. It is the best case, but I still get potential between any two of the amps. Individually, they are dead silent. I do suspect the issue is zero reference between the two, tube amps.

Hi Al. Thanks for tuning in cuz I'm just about over my head. :-) The Jesen paper is very good reference. Only difference is I think this is on the ac lines. Maybe I'm misinterpreting things. From my experiments, I get this hum regardless of interconnections between the amp inputs. Just having one of the other amps plugged in but not turned on or connected in any other way is enough to cause the hum. Still, it is cheap enough to try the audio isolators on the inputs. That may help convince me if more power side treatment will work or not.
dan_ed
2,451 posts
 
I took some measurements from each amp using the ground tab on a cheater plug with nothing turned on, just plugged in. I'm seeing 16 vac on the ground tab from one tube amp and 14 vac on the ground tab with the other tube amp. The SS amp shows no potential. I didn't bother measuring the ac current.
dan_ed
2,451 posts
 
Yes, all unbalanced. I put the two tube amps on cheaters. When they are both off I see about 2.5 vac and that drops to about 1.3 vac when both are switched on. That seems to go along with your theory, Al.

I have also been referencing this paper from Equitech's web site.

Lifting the Grounding Enigma

They seem to be saying that the balanced power approach will do the trick for my situation but I can't reason it out.
dan_ed
2,451 posts
 
Thanks for your interpretation. I believe I have the "extremely rare" occurrence mentioned in the Jensen paper. :-) I realize this probably won't eliminate all of the hum, but cutting it in half might make it liveable. I'd like to put each of these two amps on their own balanced supply. These are around 60 watt PP amps so I don't need too large of transformers. Maybe a pair of 500va on each. Finding them for an experimenting price might take some looking.
dan_ed
2,451 posts
 
Thanks for the help, guys. Jea48, even if I did that it can't be maintained with a three prong connector. Yeah, the best solution would be to pack them off and have them rewired to play together. I hate shipping them as one already has chassis damage from mishandling.
dan_ed
2,451 posts
 
The cost of the jensens and the fact that they will impact the sound doesn't make that an attractive long-term solution. I guess I'll just byte the bullet and send these off to get fixed the right the way. Can't blame a guy for trying to find an easier solution, but in the long run, there is only one way to fix this correctly.

I know my guy can fix this since he's been marketing his own monoblocks for a year now. He'll be shocked I'm finally sending these amps to him since he's been after me for a while now. :-)
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