Author Topic: 60 cycle Ground Hum  (Read 8337 times)

Offline tmazz

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Re: 60 cycle Ground Hum
« Reply #15 on: November 17, 2009, 05:34:43 AM »
I don't think you ev er mentioned what kind of amp you are using.  At this point I think you are down to two possibilities. 1) there is a problem with the electrical input to the amp or 2) there is a problem with the amp itself that needs repairing.  :(

I think the best way  to know for sure is to bring the amp over to the home of one of you audio buddies and plug it in there ( this is why I asked what kind of amp it was. If it is a bear to move it might be easier to have somebody else bring an amp to you). Either way, if your amp hums on the same AC line that another one doesn't it would seem like time from a visit with my local technician.

At least this problem sounds like it is constant. I had an intermittent problem in a power amp regulator circuitry once had stopped humming every time I brought it to a shop. Not unlike the kid who makes a miracle recovery suddenly feels well enough to go to school when his mother goes to look for the rectal thermometer. I kind of sorry we use those digital ear thermometers now. When I was growing up I think the rectal thermometer was responsible for getting more sick schoolkids on their feet than all the drugs in the pharmacy combined  :lol:

Hmmm........ I like the old fashiond analg thermometer better than the new solid state digital version. I think I see a pattern here...........

Good luck,
Tom
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Offline richidoo

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Re: 60 cycle Ground Hum
« Reply #16 on: November 17, 2009, 07:20:48 AM »
Ken uses Odyssey Stratos Mono (maybe the Extreme version?) and Mapletree Line 2A SE preamp with seperate PS module. All JPS SC3 signal wires, Black Sand power wires. Odyssey doesn't give the S/N spec on their website.

There are 2 common types of noise, hum and hiss. 60Hz hum comes from ground loop or EMI from transformer, and 120Hz hum comes from PS after rectifiers. Hiss comes from RFI, and all active circuit components (transistors and tubes) when they are powered on. You need to seal off the input jack on the amp before you listen for output hiss noise. Connect the preamp to the amp, but the preamp is not plugged in, nor is anything connected to it. This will stop any RFI getting into the amp input jack. Then listen for hiss at the speakers. It should be very quiet, if not silent.  It should be fully warmed up also. There may be very soft hiss at the speaker, but you should not be able to hear any noise at all from your listening position, even in dead quiet room. If you can hear it from listening seat, call Klauss to discuss S/N ratio or repair options. Maybe it just needs bias adjusted. If something is broken or out of adjustment, then it should not be happening on both amps. If both amps sound identical, then it is the design. Decide if you can live with it.  I never noticed any noise from them when I have visited your system, even with the horn loaded tweeter - and I am sensitive to it after living with tubes for so long.

But you should not hear any 60Hz hum from the amp with shorted input. If you hear hum with grounded input then it is either poor PS design allowing ripple on the DC rails (120Hz, not 60Hz) or poor internal layout where PS transformer magnetic leakage induces AC current on DC rails or signal wires, or else something is broken or out of adjustment. It's not poor design from Klauss, but he can give you better advice about what to try. It would be a good idea to test the amp noise with a ground buster on the outlet just to make sure it is not related to ground. Test each amp separately, and make sure they are fully warm.
Good luck!

Bigfish8

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Re: 60 cycle Ground Hum
« Reply #17 on: November 17, 2009, 02:24:07 PM »
Guys: 

I called Rich this afternoon and had a conversation about the background noise I am hearing.  He recommended I disconnect everything from the preamp except for one IC to one monobloc amp.  Then to make certain I had the amp and preamp powered from the same double outlet.  When I powered the amp up I had to place my ear to one of the woofers to hear the faintest of hash.  When I powered up the preamp the hiss/hash could be heard.  It is not that it is an extremely loud noise and I do not hear it when playing music; but, I know that background noise is a negative to sound quality. 

The Mapletree has a rectifier in the power supply and I have not evaluated a replacement.  Rolling tubes int he preamp has had no impact on the background noise.  I would also comment that I believe the background noise was present with the Timepiece Speakers but they were 85db efficient into 8 ohms where the Ushers are 90db into 4 ohms.  I believe the higher efficiency of the new speakers make the background noise more apparent.  It will be interesting to hear the impact of a different pre into the system.

Ken

Offline satfrat

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Re: 60 cycle Ground Hum
« Reply #18 on: November 17, 2009, 02:45:55 PM »
Ken uses Odyssey Stratos Mono (maybe the Extreme version?) and Mapletree Line 2A SE preamp with seperate PS module. All JPS SC3 signal wires, Black Sand power wires. Odyssey doesn't give the S/N spec on their website.

There are 2 common types of noise, hum and hiss. 60Hz hum comes from ground loop or EMI from transformer, and 120Hz hum comes from PS after rectifiers. Hiss comes from RFI, and all active circuit components (transistors and tubes) when they are powered on. You need to seal off the input jack on the amp before you listen for output hiss noise. Connect the preamp to the amp, but the preamp is not plugged in, nor is anything connected to it. This will stop any RFI getting into the amp input jack. Then listen for hiss at the speakers. It should be very quiet, if not silent.  It should be fully warmed up also. There may be very soft hiss at the speaker, but you should not be able to hear any noise at all from your listening position, even in dead quiet room. If you can hear it from listening seat, call Klauss to discuss S/N ratio or repair options. Maybe it just needs bias adjusted. If something is broken or out of adjustment, then it should not be happening on both amps. If both amps sound identical, then it is the design. Decide if you can live with it.  I never noticed any noise from them when I have visited your system, even with the horn loaded tweeter - and I am sensitive to it after living with tubes for so long.

But you should not hear any 60Hz hum from the amp with shorted input. If you hear hum with grounded input then it is either poor PS design allowing ripple on the DC rails (120Hz, not 60Hz) or poor internal layout where PS transformer magnetic leakage induces AC current on DC rails or signal wires, or else something is broken or out of adjustment. It's not poor design from Klauss, but he can give you better advice about what to try. It would be a good idea to test the amp noise with a ground buster on the outlet just to make sure it is not related to ground. Test each amp separately, and make sure they are fully warm.
Good luck!

Hey Rich, try Odessey Audio Mexico website for more accurate information on ALL Odyssey products. Eduardo's website should be Klaus's home site. ;)

Cheers,
Robin
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Offline richidoo

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Re: 60 cycle Ground Hum
« Reply #19 on: November 17, 2009, 04:40:33 PM »
Thanks Robin!

Offline bmr3hc

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Re: 60 cycle Ground Hum
« Reply #20 on: November 24, 2009, 04:26:56 AM »
Ken

What's the status of the hum? Hopefully resolved? If not what else have you tried to resolve it and what's your next step?

Henry
"If music be the food of love, play on."  Shakespeare

Bigfish8

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Re: 60 cycle Ground Hum
« Reply #21 on: November 24, 2009, 04:36:53 AM »
Ken

What's the status of the hum? Hopefully resolved? If not what else have you tried to resolve it and what's your next step?

Henry

Hi Henry:

Dr. Sol was over on Saturday to solder some resistors into my Transporter for added protection to the rectifier tube.  When I played the system for him he immediately recognized the noise as a 120hz hum coming from the preamp.  Sol investigated the situation and discovered a grounding loop in the power supply.  A few minutes later, after working his magic, the preamp was dead quite - well expect for a very faint tube hiss.  I was about the kick it out the door and since Sol repaired it I have ordered a NOS Bendix 6X5 Rectifier Tube.  Also Chris of BPT is making a new Umbilical Cord to replace the stock cord between the power supply and preamp.  I am a happy audiophile at the moment. :thumb:

We missed you at the G2G on Saturday!

Happy Thanksgiving!

Ken

Offline bmr3hc

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Re: 60 cycle Ground Hum
« Reply #22 on: November 24, 2009, 05:18:40 AM »
Awesome Ken. great to hear that the "hum" problem solved and by none other than Dr. Sol, the problem Sol'ver. Wish I could have been there on Saturday. Still nursing a cold. The good part is I was able to listen to music for hours.

Henry
"If music be the food of love, play on."  Shakespeare