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Hi Mike, how was your summer?
I have a two part question about the Sherwood S-5000.
If I use any tube other than the RCA black plates in the V5 position I get both a hum and a buzz.
I purchased a Gold Lion LPS (something like that from Jim) to remove the possible hum from the filament. It did remove the hum, but there is still a buzz. Like a low level motor boating buzz. But very noticeable.
Any ideas what the heck that is?
And what should I be looking for in other tubes to replace it with when that time comes. Because I ALWAYS like to have a set of replacement tubes!!!!!!!! I'm paranoid that way.
Also is the V4 and V5 positions simply a phase splitter and the main sonic tube the V3?
charles
Follow Ups:
Improper tube shielding.
I improvised and used tin foil to wrap the V5 tube and put the metal cage back on. Nothing like tin foil and a few hundred volt pins in proximity.
It was dead quiet with the Gold Lion ECC83/B759. And there was still a faint hum with the TungSol ECC803S/12AT7. So that was the problem and now I can tube roll to my hearts content.
So I have to find a set of tube shields.
Hi Charley, I have extra tube shields hangin around. Most are for 12ax7 size tubes...let me know...Mark...kordamark@gmail.com
I could use a set of three. I plan on putting in an order with Jim around the holidays. But I do need them now if I want to use my other tubes.And yes the tubes are 12AT7's.
Thanks
charles
Edits: 09/27/15
Hey Charley, I got 3 in my hand right now. Email me your address and I'll send them out tomorrow. My email has changed but I can't seem to re-program it on Asylum, so this is it(kordamark@gmail.com).I think these came off an old Dyna FM-3.They will be glad to be reused in a Sherwood amp that combines the efforts of 4 great hifi nuts. The designer, Sherwood? The builder? The re-builder Mike. And you. There waiting for you...Mark.
...with a Fisher 500C. Certain tube(s) in the phase splitter would hum while another would not. If I remember correctly, the Fisher brand tube did not.
-reub
That sounds like you may need to clean your test-normal switch in the back of the unit.If not that,clean and tighten those sockets again..We all love rolling tubes and when we do that,we have to retighten sockets every so often..
Nobody ever went broke underestimating the intelligence of the American public
H. L. Mencken
Hello Mike from your neighbor! Ask John S. who this may be.
Joseph
When I use new tubes, eg TungSol, Gold Lion, I get the hum/buzz
When I use vintage tubes, eg Bell&Howell, RCA, Zenith, I get NO hum/buzz
SO what characteristic does the old tube have over the new tubes.
thanks
charles
Hi Charley, you said when you use the new tubes you get a hum. I'm reading out of a book that an under biased amp can cause hum. You didn't say if you reset the bias or not. Just an idea, got nothing else going except Son of Frankenstein on ZwenGoolie tonight...Mark.
Try cleaning the hum switch in the back where you balance the tubes or just move it back and forth a few times really fast..Are you putting the shield back over the tubes?
Nobody ever went broke underestimating the intelligence of the American public
H. L. Mencken
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