Tweed Twin 5E8-A Grid Resistors?

Diablo · 08-25-2009, 11:41 PM

Before I start my kit build, I'm reviewing the schematic and notice that there are no input grid stopper resistors on the 12AY7 tubes. This is different from most other tweeds that have 68K resistors. So, should I add 68K grid stoppers to prevent oscillation and minimize pickup of stray signals? Any reason not to add the grid stoppers? What was Leo thinking?

tubeswell · 08-26-2009, 02:04 AM

Hi Diablo

Could you please try it both ways and report back?

(I'm trying to decide what my next build is going to be)

Diablo · 08-26-2009, 03:25 AM

Gee, I'm trying to do less work, not more....

OK, I think I'll add the grid stoppers, then bypass them with a jumper and see if it makes a difference. I'm also building this amp with Vari-watt from Skipz-circuits. It should be an interesting journey.

Diablo · 09-05-2009, 09:04 PM

I checked out the schematic of the 57 twin reissue and discovered they put in 1.5K grid stoppers on the input tubes. So, I changed out the 68K grid stoppers I had in it to the 1.5K stoppers. Didn't seem to make much difference to my old ears, but I figure a little hotter signal is a good thing.

08-25-2009, 11:41 PM	#1
Diablo Senior Member Join Date: Dec 2007 Posts: 505	Tweed Twin 5E8-A Grid Resistors? Before I start my kit build, I'm reviewing the schematic and notice that there are no input grid stopper resistors on the 12AY7 tubes. This is different from most other tweeds that have 68K resistors. So, should I add 68K grid stoppers to prevent oscillation and minimize pickup of stray signals? Any reason not to add the grid stoppers? What was Leo thinking?

08-26-2009, 02:04 AM	#2
tubeswell Supporting Member Join Date: Feb 2007 Location: Wellington NZ Posts: 2,662	Hi Diablo Could you please try it both ways and report back? (I'm trying to decide what my next build is going to be) __________________ Building a better world (one tube amp at a time)

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08-26-2009, 03:25 AM	#3
Diablo Senior Member Join Date: Dec 2007 Posts: 505	Gee, I'm trying to do less work, not more.... OK, I think I'll add the grid stoppers, then bypass them with a jumper and see if it makes a difference. I'm also building this amp with Vari-watt from Skipz-circuits. It should be an interesting journey.

09-05-2009, 09:04 PM	#4
Diablo Senior Member Join Date: Dec 2007 Posts: 505	I checked out the schematic of the 57 twin reissue and discovered they put in 1.5K grid stoppers on the input tubes. So, I changed out the 68K grid stoppers I had in it to the 1.5K stoppers. Didn't seem to make much difference to my old ears, but I figure a little hotter signal is a good thing.

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