Richard Knoppow wrote:
----- Original Message ----- From: "Kevin Nathan" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Saturday, January 15, 2011 9:44 PM
Subject: Re: [Drakelist] Noise In R4-C
Hi Gary,
I'm sending this copied to the list as well so Evan and Lee can see the
results. I pulled the cover off the R4C tonight and my wife and I
exchanged
those tubes with each other. Her smaller fingers were invaluable
getting V4
back into its spot. <GRIN> It's been perking for an hour or more now
and
the noise is gone. Thank you so much for that suggestion. I think I
might
investigate the solid state replacements that Evan suggested through
Sherwood Engineering though but for now the problem seems fixed.
Help from all of you is very much appreciated. Take care everyone
and very
73.
Would be interesting to swap the tubes back and see if the problem
returns. Perhaps just excercizing the contacts in the sockets fixed it.
Richard -
Possible, but the 6EJ7 is well known for causing that problem in that
spot. Not sure exactly why, no intellectual curiosity I guess. :-)
Probably a combination of gain and signal levels, but it is a 'frying'
sound, NOT 'white noise', but a random crackling very like frying
bacon. Some tubes do it "new", others do not. Some do not, but after
many hours, do! I have cleaned sockets, examined other components
involved, etc., but nothing 'wrong'. There doesn't seem to be any brand
variation either. The 6EJ7 is a very high mu, low plate resistance
tube, meaning very close element spacing, but I have no idea if that has
anything to do with it! :-)
Just to add insult to injury, the same tube seems to work fine in the
PreMixer and even 1st Mixer socket.
As an aside, I believe this problem was the impetus for Sherwood to come
up with his first 'modification' board, a solid state 3rd Mixer.!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
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