Welborne Labs Revellie tube preamp excessive hum, need help

[LonestarBlues]

Hello, Fedex delivered the Revellie preamp this afternoon, no manual. I hooked the preamp up and it has a very excessive loud hum that is unacceptable through my 1977 Cornwalls. No hum like this with my Mcintosh solid state preamp. I have read on the Welborne Labs forum at the Asylum that the Revellie preamp is prone to ground loops due to the the use of input transformers. Ron Welborne suggested to that individual to lift the ground on his amps. Does this mean using what I call a cheater adaptor-3 prong grounded cord into a 2 prong

adaptor plug for use with outlets that do not accept grounded power

cords. I tried the cheater plug adaptors and they did not quiet the hum any at all. Thanks for any help to help me solve this problem.

Regards, Mike

[NOSValves]

Try it and see if it helps. It surely won't hurt it that is for sure ! 3 wire power cords are strickly a safety measure and have only drawbacks and no positive sound wise. The only positive is it keeps you from being able to shock yourself if something goes wrong with your gear.

Craig

[AnalOg]

Is the hum in both channels, are the interconnects connected to preamp and your source?

Tom

[LonestarBlues]

The hum is from both channels with the system hooked up with my Mcintosh cd player & tuner. I can hear the hum from across the room

in my listening chair. My room is 25'L x 19'W with 8' ceiling. I have 1977 Cornwalls on the long wall 16' apart toed in. I can hear residual hum when I play music. The solid state Mcintosh preamp had a very slight hum when you put your ear right next to the speakers with no music playing & no residual hum with music playing. I used cheater plugs on both the amps & preamp and it did not quiet the hum down. The guy on Welborne Labs forum that had hum with his Revellie said that he grounded his cd player and changed to a better shielded cable to quiet the preamp down to a residual hum with his ear right next to the speaker. How does one ground a cd player and what size wire would I use? Would it be similar to grounding a turntable? I am also getting bleed through if I have my tuner turned on the same time my cd player is on with the cd source switch on and no music playing. The Mcintosh was dead silent with no bleed through. Thanks for any suggestions to help remedy this ground loop problem.

Regards, Mike

[Tom Mobley]

Does it hum with no source devices hooked up to the input terminals?

Tom

[LonestarBlues]

I turned the system off and disconnected the cd & tuner interconnects from the preamp input. Turned it back on & the hum was gone. Had a little faint white noise from the tweeter if you put your ear right up next to the speaker. I posted over at the SET forum at the Asylum to get help also. I emailed Dave sK, the guy at the Asylum who had hum problems with his Revellie and reduced the hum on his. Ron Welborne is off to Lima for the Midwest Audio Fest & his answer to Dave sK was to lift the ground on his amp. Thanks for any help, advice & guidance.

Regards, Mike

[NOSValves]

Is this preamp new !

[Randy Bey]

Sounds like ground loop problems to me, if you disconnected other sources and the hum went away.

Are the other sources 2-prong or 3-prong? Try one at a time adding them back in, and reversing the plug if 2-prong. For 3-prong you'll need a cheater (but only temporarily).

My system hummed like a b*st*rd when I had the antenna hooked in from the attic -- go figure.

[Deang]

"Lift the ground", R Welborne's answer for all hum problems with his stuff.

Any chance of getting that thing on it's own outlet?

Personally, I think you should just sell it and save yourself some grief.

I'm not a big fan of Ron Welborne. After I bought the Apollo's, I posted some questions about the amps on the Welborne Forum. I had received two manuals with the amps -- and they were very different in respect to layout and various parts values. I was simply trying to figure out which was the superior design. I felt his response was condescending and unprofessional. To a degree, it contributed in part to my descision to unload the Apollos. I really felt that if I had a problem with them, I wasn't going to get much in the area of technical support.

[LonestarBlues]

Hello guys. Thanks for all the help. I have solved the ground loop problem with Y'alls help. I hooked up the sources one at a time. The Mcintosh MR 77 tuner is the source causing it. I have a spare Technics ST8077 tuner from the late 70's-early 80's. I hooked

the Technics tuner up and it does not cause the ground loop hum and there is no bleed through with the Technics in the system. I removed

the cheater plugs. Don't know why the Mcintosh causes hum problems. I will hook it up to my alternate Mcintosh solid state system. The Mcintosh is in the same rack and hooked up to my 1983 Cornwalls which are on the opposite long wall from the 1977 Cornwalls. I bought the Revellie used from Audiogon. Again thanks for the help.

Regards, Mike