Power cords, a trip into the unknown!
- Thread starter DaveyF
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edit: not a small loop..wrapped the entire length.
Yes, it is certainly worth a try. Even balanced can have the problem, this is generically a pin 1 problem.
But first, just try proximity to. If that reduces the hum/buzz at all, then that would seem to indicate strongly that it's ground loop pickup.
If that does indeed work, then it would probably "behoove" Ray to give me a call. (I love that word..behoove.. It behooves me.. )..
..I have tests which will force that issue, so that the designer can fix it out, make the amp bulletproof.
Cheers, jn
My first thought is no.
My second is, try moving the IC's around. I've solved problems by actually twisting the ic's around the power cords ( although my example of 125 foot cords is kinda extreme).. Think of the IC's and power cords as defining a loop in space, and that any magnetic fields in the area that are able to go through that loop can make noise. If you reduce that physical loop size, you reduce the amount of magnetic field that can go through it.
Almost everybody I hear tends to say that power cords and IC's don't mix, keep em apart, keep em 90 degrees... None of that is correct... another windmill for me to tip at...
Cheers, jn
My listening experience obviously doesn't jive with yours. It's so apparent when an AC cord runs parallel to a PC in my system--sometimes so much that I have to check that my cats haven't moved my cords (that's by laying on them
). Anyway, the most apparent sonic artifact is a brightness and silverly sheen to the sound when AC cords and ICs are in the immediate vicinity.Interesting.My listening experience obviously doesn't jive with yours. It's so apparent when an AC cord runs parallel to a PC in my system--sometimes so much that I have to check that my cats haven't moved my cords (that's by laying on them
Balanced, unbalanced, shielded, twisted, q's?
Simple proximity of two twisted pairs where there is an integral relationship between twist pitches can easily couple more. When I twisted my ic's around my power cord, I made very certain that the twist pitch of the power cord was not duplicated by my twisting the ic's.
Two cables with either the same pitch, or an integral number will couple strongly in proximity. If the ic's for example, twist at twice per foot and the line cord once per foot, they will couple strongly.
Cat5e cable kills this coupling by virtue of 4 different twist pitches internally.
My point to mep is that if movement of one cord in relation to another causes a system change, then that is a strong indicator that the system has coupling between external magnetic fields and the input circuitry. In your case, it would seem that the power drawn is coupling to the input circuitry.
Cheers, jn
Couple of thoughts, Mark ...
Have you tried as a short term experiment plugging the Krell into the same socket as the rest of the gear?
Maybe you have a DC offset on the mains voltage upsetting the transformer, try inserting a DC blocker in the mains line.
Frank
Have you tried as a short term experiment plugging the Krell into the same socket as the rest of the gear?
Maybe you have a DC offset on the mains voltage upsetting the transformer, try inserting a DC blocker in the mains line.
Frank
edit: not a small loop..wrapped the entire length.
Yes, it is certainly worth a try. Even balanced can have the problem, this is generically a pin 1 problem.
But first, just try proximity to. If that reduces the hum/buzz at all, then that would seem to indicate strongly that it's ground loop pickup.
If that does indeed work, then it would probably "behoove" Ray to give me a call. (I love that word..behoove.. It behooves me.. )..
I have tests which will force that issue, so that the designer can fix it out, make the amp bulletproof.
Cheers, jn
I tried moving the ICs around and the hum level doesn't change. I'm sure the hum/buzz is originating from the power transformer as you can plainly hear it when you get your ear next to the top of the amp. I tried wrapping the left channel IC around the PC and that made no difference either.
I took a look at a cheap 10A PC and after noting that it plugs in perfectly to the KSA-250, I could see the snout of the cheap PC female connector was a little longer than the snout on my PS audio cord which I think is allowing it the greater stability I normally see with all "regular" power cords.
My bold... Are you saying it is a mechanical/physical buzz from the transformer/chassis itself? Moving cords and rerouting power will not fix that. If that's the case, you either need a new transformer, or better isolation of the transformer's mass (usually accomplished with little rubber/plastic donuts). That is a design issue, not a consumer issue...
I have separate 20A outlets in my listening room.
I've always put the amp/s on a different circuit than the preamp and never had any problems until I tried a Decware Zen TORII MK III a couple of months ago.
With the same ICs & PCs I was getting hum/noise with the Zen TORII MK III. I floated the ground on the amp's PC and the hum was reduced but still there.
Plugged the amp and preamp into the same AC outlet and the hum/noise was gone.
Hi Don,
What makes transformers buzz mechanically? I've always been curious about that.
TIA
Jack
What makes transformers buzz mechanically? I've always been curious about that.
TIA
Jack
@mep
It could be interesting to bring all the ground in your system to the same potential.. Different ground potentials (voltage if you will) do tend to allow those "ground loops". If plugging the preamp and amp on the same circuit eliminates the hum, then this is an indication of your various grounds at different potential .. Using a 4th wire to link the ground usually works very well in these situations. I don't know if that is against (US) codes but I do think that is allowed for server rooms in Data Center Electric infrastructures.
I am not sure that changing power cords would change this however ...
@J_N ..Welcome to the WBF ...
It could be interesting to bring all the ground in your system to the same potential.. Different ground potentials (voltage if you will) do tend to allow those "ground loops". If plugging the preamp and amp on the same circuit eliminates the hum, then this is an indication of your various grounds at different potential .. Using a 4th wire to link the ground usually works very well in these situations. I don't know if that is against (US) codes but I do think that is allowed for server rooms in Data Center Electric infrastructures.
I am not sure that changing power cords would change this however ...
@J_N ..Welcome to the WBF ...
I agree. As Jim Weill pointed out, you could have a problem with the dedicated lines being set up on either the same or opposite legs.
About the only thing i dislike about my Rowland model 8 is that it hums. Many years ago, i talked to Jeff about this issue. He told me that his Far East clientele had insisted that he fix this problem and so he had to do away with the choke power supply in these amps to address the problem. ( although in many ways, i think by doing this he threw away the baby with the dishwater....great saying don't you think..)
What I have noticed in the many years since that conversation is that hum seems related to many variables...even with a dedicated line,for instance it will depend on the time of day that I am listening and other less repeatable variables. ( I do think the power surges and drops from the dear local power Co., can still cause issues).
BTW, my DIY Supra cable with the Wattgate plugs is FAR superior than the stock 20 amp cord that comes with the amp, a great 20 amp iec is very important , IMHO.
. Many years ago, i talked to Jeff about this issue. He told me that his Far East clientele had insisted that he fix this problem and so he had to do away with the choke power supply in these amps to address the problem. ( although in many ways, i think by doing this he threw away the baby with the dishwater....great saying don't you think..)What I have noticed in the many years since that conversation is that hum seems related to many variables...even with a dedicated line,for instance it will depend on the time of day that I am listening and other less repeatable variables. ( I do think the power surges and drops from the dear local power Co., can still cause issues).
BTW, my DIY Supra cable with the Wattgate plugs is FAR superior than the stock 20 amp cord that comes with the amp, a great 20 amp iec is very important , IMHO.
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