Bass loss with balanced cables? [Archive] - Audio & Video Forums

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Ja Galus
07-20-2004, 12:05 AM
A few days ago, I had an opportunity to test two "high end" cables. They were the same series, but one was "balanced" the other was not. (Using Bryston amp and preamp.) Both cables were 1M length. I was under the assumption that the balanced version would be a little "better" or at least equal to the unbalanced version, but to my dismay, I found that my bass was reduced (mostly mid bass) quite a bit with the balanced version.
Has anybody out there had a similar experience with balanaced vs.unbalanced cables?

skeptic
07-20-2004, 06:30 AM
Since both cables should respond down to DC, the only explanation I can think of is that one or the other inputs has additional elements which causes the loss. Most likely the balanced input has to go through a transformer or a unity gain stage to match it to the next stage. If you can get a copy of the schematic, look carefully a the two amplifier input circuits and compare to see what differences there are. Also compare the preamp output circuits. An addition capacitor or transformer might do it. Have you contacted Bryston to get their explanation? It is disappointing that the difference is significant enough to be audible in equipment of this cost and quality.

jneutron
07-20-2004, 07:44 AM
A few days ago, I had an opportunity to test two "high end" cables. They were the same series, but one was "balanced" the other was not. (Using Bryston amp and preamp.) Both cables were 1M length. I was under the assumption that the balanced version would be a little "better" or at least equal to the unbalanced version, but to my dismay, I found that my bass was reduced (mostly mid bass) quite a bit with the balanced version.
Has anybody out there had a similar experience with balanaced vs.unbalanced cables?
What does the unbalanced cable do with the input connection that is not used? Is it open, or shorted to ground.

John

Ja Galus
07-20-2004, 12:32 PM
Thanks for your recent inquiry about bass performance in your
Bryston BP-25/3B ST combination. I can think of no measurable
reason why bass performance shoud be affected by the type of
cable used in the interconnects. Unless the balanced output of the
preamp is malfunctioning in some way, the bass extension and
tonality should be exactly the same with either input/output
combination.

If you have concerns about whether your preamp is working
correctly, the CDN service office will be pleased to check it at N/C.

I hope the above information is satisfactory, but please
let me know if you have further questions. Thanks for your
support for Bryston audio components!

Sincerely,
Christopher W. Russell
CEO, Bryston Ltd.

markw
07-20-2004, 03:46 PM
Perhaps the difference originates in the source unit and not the Bryston?

Bobby Blacklight
07-20-2004, 07:22 PM
Just a thought but could one of the balanced cables have the two signal leads swapped?? Can you ohm them out??

jneutron
07-21-2004, 05:25 AM
Just a thought but could one of the balanced cables have the two signal leads swapped?? Can you ohm them out??
Oooo..good thought...I didn't think of that.

He did say that the mid bass was affected, as opposed to the bass or low bass..So I'm thinking that it's not an inverted channel.

Ohming the cables is a good idea, though..

John

mtrycraft
07-21-2004, 09:40 PM
Oooo..good thought...I didn't think of that.

He did say that the mid bass was affected, as opposed to the bass or low bass..So I'm thinking that it's not an inverted channel.

Ohming the cables is a good idea, though..

John

One side out of phase?

jneutron
07-22-2004, 05:03 AM
One side out of phase?

From an inverted channel, yes..but he said mid bass, not low.. Out of phase would have it's most effect on lower bass, and virtual image would be destroyed..that is why the loss of mid bass only is weird.

I note with some satisfaction, something else entirely...a hypothesis I had formed a while back...

Over at the looney bin (where I also hang out) anecdotal accounts of line cord sensitivity for amplifiers included most amplifiers, but for some reason...Bryston amps did not have reports claiming this...in fact, most anecdotes were that Bryston amps did not show any sensitivity at all..

When I formed the line cord drawing, with transfer equations, I had figured out how to eliminate the internal to amp sensitivity....and that was with a balanced input, configured to catch the loop coupling, and subtract it in the amp.

By taking a differential amp input, and shorting one of the inputs via the input jack, you keep the loop coupling to the unused input intact, and any pickup will be common to both input polarities..subtracted by the cmrr..

Interesting...almost warranting another thread...or a continuation of the origional..

Cheers, John