Thanks for the update. When I get a chance, I'll check my Capri to see if it is an issue as well. But, I don't have any ground hum (except for a little EMF hum from the phono input only at max gain).
Insane ground loop; anybody wanna try?
I have a ground loop that's been killing me for weeks. I've tried several things to limited or no success. I've written to Mike Sanders at Quicksilver, but I'm a little chagrined to keep asking him questions that aren't really the fault of his gear.
Anybody want to have a go at solving this puzzle? It's driving me nuts, and I'd be grateful for any help.
Relevant equipment:
Rowland Capri preamp
Quicksilver Silver 60 mono amps (EL34)
Sunfire True Sub
Amps, preamp, and sub are all plugged into a Monster 2000, so everything shares a common wall outlet.
Plugging the amps into separate wall outlets has little effect either way.
Amps are damn near dead-quiet with no input, so it's shouldn't be the transformers or the tubes.
Amps plugged in to the preamp (shielded DH Labs RCA cables) hum, and the sub does too. Swapping cables has no effect.
Unplugging and reconnecting sources (a turntable and a Mac Mini via a Schiit DAC) has no effect.
Unplugging the sub has little effect (except it eliminates the hum in the sub, haha).
Lifting the ground on the amps reduces the hum — by about half, but definitely not completely.
A Hum-X has no (or very little) effect, whether placed on the preamp, an amp, or the sub.
For obvious reasons I don't want to lift the ground on the amps permanently.
I'm not an electrical engineer, but I'm a logical guy.
Ideas? I'm open to any with two requests: First, if you don't know something for sure, please say so. I don't want to play in electron traffic because somebody just guessed at a solution. And second, if you disagree with somebody, don't call him names, okay? There's more than enough gratuitous meanness in the world right now without insulting people over stereo equipment. Thanks.
Anybody want to have a go at solving this puzzle? It's driving me nuts, and I'd be grateful for any help.
Relevant equipment:
Rowland Capri preamp
Quicksilver Silver 60 mono amps (EL34)
Sunfire True Sub
Amps, preamp, and sub are all plugged into a Monster 2000, so everything shares a common wall outlet.
Plugging the amps into separate wall outlets has little effect either way.
Amps are damn near dead-quiet with no input, so it's shouldn't be the transformers or the tubes.
Amps plugged in to the preamp (shielded DH Labs RCA cables) hum, and the sub does too. Swapping cables has no effect.
Unplugging and reconnecting sources (a turntable and a Mac Mini via a Schiit DAC) has no effect.
Unplugging the sub has little effect (except it eliminates the hum in the sub, haha).
Lifting the ground on the amps reduces the hum — by about half, but definitely not completely.
A Hum-X has no (or very little) effect, whether placed on the preamp, an amp, or the sub.
For obvious reasons I don't want to lift the ground on the amps permanently.
I'm not an electrical engineer, but I'm a logical guy.
Ideas? I'm open to any with two requests: First, if you don't know something for sure, please say so. I don't want to play in electron traffic because somebody just guessed at a solution. And second, if you disagree with somebody, don't call him names, okay? There's more than enough gratuitous meanness in the world right now without insulting people over stereo equipment. Thanks.
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- 61 posts total
@edwyun I haven't received a response from Rowland, so that would actually be super-helpful if you'd be willing to check. (I'll holler at them if I don't hear by tomorrow.) The thin trace is on the top side of the power board, in the corner where the ground ring connects to the AC receptacle two inches away. (Since the cover is on the bottom, you can't see the top side without unscrewing the board, but it's super-easy, just four hex bolts.) Here's a photo of the board and the ground I'm wondering about: https://www.dropbox.com/s/xkhm3lnsog45auy/Capri-ground-7D2_4666.jpg?dl=0 If you get a chance, let me know if yours looks the same. Thanks a lot! |
Here's mine. It looks the same. BTW, that trace is not for the ground but for a capacitor. So I don't think it is an issue. http://www.audiokarma.org/forums/index.php?media/20170308_193253.9518/full |
These will give you more data: Try temporarily running a wire from the preamp case to amp case. This assumes both cases are connected to their respective ground paths. Could also be a problem with a cable or jack. Any oxidized jacks? Does every cable between the components cause hum? Test with only one connected at a time. If hum is only from one, try a different cable on that jack to jack path. Heck if stumped I might try reversing the cables, one at a time, to see what happens. That is mainly if the cables are directional. If none of this makes any difference, then you know the problem is most likely internal to the preamp. |
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- 61 posts total