Author Topic: Is there a simple way to fix impedance mismatch in pre/power?  (Read 9148 times)

Offline Doggie Howser

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So I like the Ayon CD5S.

And I like the Focal Solo 6 Be

But I encountered what I suspected was an impedance mismatch issue. There's like static in the sound. Very high hiss. But it's oddly enough an intermittent problem and wasn't obvious at first.

So I used the Bel Canto Pre3 in between and that fixed the problem.

Ayon CD5S specs:
Output impedance  Balanced-XLR
 ~  300 Ohms

Focal Solo6Be
Type/Impedance: symmetrical/10 kOhms

Is it likely that impedance mismatch to be the cause of the issue?

I don't really want another preamp in the loop. Is there a simple in-line solution to fix this?
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Offline Doggie Howser

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #1 on: January 26, 2012, 14:37 »
Hmm.. looking at the Bel Canto Pre3 specs:
Input impedance: 20kOhms balanced
Output impedance: 500 Ohms Single Ended, 200 Ohms Balanced

Is that enough?
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Offline AndrewC

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #2 on: January 26, 2012, 17:21 »
IME impedance mismatch will manifest itself with the overall sound quality, like a missing bottom or rolled off top etc. It wouldn't be intermitten static (is it truly intermitten, or always as the same point in a musical piece?). The CD5S' tube output has no buffer stage, and that bass/midrange "150W rms, BASH® technology" on the Focal sounds freaky if you ask me ;D....

You tried tweaking the Focal's input sensitivity controls?
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Offline Doggie Howser

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #3 on: January 26, 2012, 17:50 »
I've encountered this on and off with different tube preamps.

When I used the Schiit Lyr as a preamp to the Quad 606 power amp, I also encountered the same problem. Sam symptoms. Switching the Lyr out for a W4S DAC2 again fixed the problem.

The Focal uses a BASH amp for the woofer, but a Class AB for the tweeter. Overall, no complaints with the SQ.

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Offline AndrewC

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #4 on: January 26, 2012, 18:01 »
The only time I've encountered something similar in the past was when my VTL7.5 Pre was connected to my Kharma Class D monoblocks via MIT Oracle speaker cables... intermitten screeching. Changing to straight copper speaker cables solved the problem.... the Class D Amp didn't like the zobel network for whatever reason or something.

I'm guessing similarly in your case, it's probably not an impedance issue per se...
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Offline Doggie Howser

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #5 on: January 26, 2012, 18:03 »
Nothing fancy. Just some Audioquest shielded interconnects.

No screeching. Just a very high hiss with no signals playing and when music is playing, it's like there's radio static overlaid.
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Offline pcking

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #6 on: January 26, 2012, 19:25 »
R u using Low or High Output setting on your CD5S ?

Don't think your problem is due to impedance mismatch.
« Last Edit: January 26, 2012, 19:26 by pcking »
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Offline Doggie Howser

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #7 on: January 26, 2012, 19:29 »
I have tried both. Both have the same problem.

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Offline jimi

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #8 on: January 26, 2012, 20:47 »
My power amp have a low input impedance so a relative mismatch is easily done- but it's never resulted in hiss- a lethargic low on dynamics sound seems most prevalent. 

If the hiss is equal from both spkrs then it's likely to do with a gain mismatch and high sensitivity spkrs. So perhaps the CD5S gain alone is more than CD5s+pre3 gain?

If the hiss is not equal then there's something really wrong.

Though hiss is not supposed to be cable related my spkrs go dead quiet if I'm using balanced, even if i crank up the volume when no music is playing with my ear next to the tweeter (no helpful to u as ur already eliminated the cables).

Offline Doggie Howser

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #9 on: January 26, 2012, 21:34 »
I have used high and low gain, phase at 0 and 180. Both exhibited this problem.

I've also encountered something similar when I used another tube preamp (Schitt Lyr) with a Quad 606 power amp.

It's not a soft hiss, but something like radio static. Weird

Using BCD Pre in between fixes this.
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Offline Doggie Howser

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #10 on: January 26, 2012, 21:43 »
Hmmm I was using the Quad 12L actives with the Ayon before this with no issue. And checking the specs, the input impedance is ALSO 10kohms.

I was using the Ayon CD5S as a preamp direct to power amps in my media room as well as a full output CDP to my preamp. The difference that I can tell is that I was using a PurePower to output 230V to the Ayon.

In my study the Ayon is plugged to an Essential Sound Reference distributor to the wall. Would that account for this problem?
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Offline vajrasattvasg

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #11 on: January 26, 2012, 23:26 »
Hmmm I was using the Quad 12L actives with the Ayon before this with no issue. And checking the specs, the input impedance is ALSO 10kohms.

I was using the Ayon CD5S as a preamp direct to power amps in my media room as well as a full output CDP to my preamp. The difference that I can tell is that I was using a PurePower to output 230V to the Ayon.

In my study the Ayon is plugged to an Essential Sound Reference distributor to the wall. Would that account for this problem?


two quick tests..

dont think its an impedance problem, you can drop in a passive pre-amp (just a potentiometer) like 50k or something in between just for experimental sake, that should drop the load seen by the cdp and see if the problem goes away

are the quad 12L grounded/earthed in anyway? i had a high pitch problem that existed due to poor grounding in the signal area.

maybe can try putting in the belcanto pre again, but use a 2 pin adapter on the powercord (so that any possible earth connection is not available) and see if problem persists. then can verify if its an "earth" problem or not.

else substitute a generic power bar in place of the previous distributor is also another experiment
maybe the human ear isn't good enough. we need measurements, figures, numbers, calculations to tell and convince us what good sound is. or do we have to satisfy an unspoken insecurity??

Offline Doggie Howser

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #12 on: January 26, 2012, 23:30 »
Ayon direct to Quad actives in SG no problem.

Ayon direct to Bel Canto REF1000M in Aus with PurePower no problem.

Ayon direct to Focal actives in Australia with 250-260V AC to ESP distributor. Problem.

Ayon line level to Bel Canto Pre to Focal actives in Australia wih 250-260V AC to ESP distributor. No problem.

See what I mean?

Cables are Audioquest active shielded XLRs.
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Offline vajrasattvasg

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #13 on: January 26, 2012, 23:53 »
Ayon direct to Quad actives in SG no problem.

Ayon direct to Bel Canto REF1000M in Aus with PurePower no problem.

Ayon direct to Focal actives in Australia with 250-260V AC to ESP distributor. Problem.

Ayon line level to Bel Canto Pre to Focal actives in Australia wih 250-260V AC to ESP distributor. No problem.

See what I mean?

Cables are Audioquest active shielded XLRs.

tricky. but i just have a hunch that it probably lies in the ground/earth, i.e. that the bel canto pre3 offers a "drainage" point  for the shielding on the XLR cabling.

not too sure how to explain it, but this site offers some possibilities http://www.rane.com/note110.html
maybe the human ear isn't good enough. we need measurements, figures, numbers, calculations to tell and convince us what good sound is. or do we have to satisfy an unspoken insecurity??

Offline Doggie Howser

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Re: Is there a simple way to fix impedance mismatch in pre/power?
« Reply #14 on: January 27, 2012, 00:26 »
Weird. Maybe I'll bring the bring the SA conditioners next to test.
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