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Signal Degradation Balanced Output

Has anyone developed a workaround that solves signal degradation when splitting. The problem that I have occurs even when the preamplifier has two balanced outputs.

Years ago I became aware of this problem when using my Sonic Frontiers Line 3, which has 2 pairs of balanced outputs, to drive a Theta Dreadnaught amp and a pair of Entec LF-20 subs. I thought the sound was excellent until oneday, I disconnected the cable to the sub and that’s when I heard what I had been missing from the Wilson Cub I, transparency and reverb that allows you to hear deep into the music.

Now, I’m running Focal Mini Utopia Be, Denafrips T+ DAC to Athena Pre, which has 2 pairs of balanced outputs driving a ARC VT-130 and a Focal Sub6. Same problem! I’ve tried inserting my Jeff Rowland Model 112, then tapping off the speaker terminals with a Jensen ISOMAX transformer which then goes to sub.. the problem persists.

The problem isn’t huge, it’s just that the higher the resolution of the components, the more noticable it is. My setup needs the lower fundamentals that a sub brings, but at a cost I’m not happy with.

Any ideas?




cathy062
imhififan's avatar
imhififan
2,184 posts
 
I was using it from the amp's output to be converted to a balanced line level that is then sent to the sub. Same problem.
Have you tried turn off the subwoofer instead of disconnect it from the amp output?
cathy062 OP
15 posts
 
Yes, I have.. no change.  The change comes from disconnecting the balanced cables from the sub or disconnecting the ISOMAX from the amp.  At first I thought it might have something to do with channel summing circuitry of the sub, but not so.
cathy062 OP
15 posts
 
@cleeds I feel like you're on the right.  Let me look into that.  I know already that the problem still persist when only one balanced output from the preamp is connected to the Jeff Rowland amp input, while the amp's output is sent to the speakers and to the ISOMAX line level converter.  The sub doesn't even need to be connected to the ISOMAX... Just connecting the ISOMAX to the amp is enough to cause the problem.
pauly
1,012 posts
 
I suspect your ISOMAX is creating a different problem than the one created by  employing your pre amp's two outputs simultaneously. 

As you correctly concluded a few posts up, your ISOMAX is not a product one can associate with audiophile quality sound. Whether you apply it to a line level signal or an output level signal, nothing good is going to come out of it. Your idea is sound, but you need to step up to a product that is substantially better (and sadly, much more expensive).

Active crossovers present the same dilemma - the vast majority (all?) of them are complete junk and sound terrible. I believe Bryston made a hifi quality crossover but I could never track one down to try.

I think there is value in considering that the combined (i.e. lowered) input impedance of your ARC and Focal makes the Athena unhappy, but I'm at a loss as to how you would test that. 

In your shoes, I would probably roll with a set of full range floor standers and junk the sub. Not a cheap solution but the safest I would think. 




atmasphere's avatar
atmasphere
11,806 posts
 
Has anyone developed a workaround that solves signal degradation when splitting. The problem that I have occurs even when the preamplifier has two balanced outputs.

Years ago I became aware of this problem when using my Sonic Frontiers Line 3, which has 2 pairs of balanced outputs, to drive a Theta Dreadnaught amp and a pair of Entec LF-20 subs. I thought the sound was excellent until oneday, I disconnected the cable to the sub and that’s when I heard what I had been missing from the Wilson Cub I, transparency and reverb that allows you to hear deep into the music.
I think @cleeds got this right. The impedance of the two inputs is a bit much for your preamp. especially when the ISOMAX is involved. One solution would be to have a preamp that supports the balanced line standard (many 'high end balanced' preamps don't). Some of the ISOMAX transformers present the preamp with a rather low impedance. Unless the preamp is really designed (which, if its balanced, it should be, but regrettably most high end audio manufacturers were simply jumping on a bandwagon with their balanced entries...) for the low impedances which are common with balanced operation, its likely to fall flat on its face when presented with such things, as you've described.

A different ISOMAX **might** solve the problem if its able to present the preamp with a higher input impedance. But that would still be in parallel with whatever the input impedance of your amplifier is.


I run a similar setup but my preamp doesn't care about the low impedance loads involved.

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