Fender TR SF. Humming like crazy only with the outer tubes in place. - Page 2

doozerdave · 8th April 2012, 01:42 PM

Glad to hear you found the problem.

My silver face Super Reverb has them inside, so I assumed your TR was the same.

Dick Deviant · 8th April 2012, 04:22 PM

Cheers! That makes sense. Mine was the final SF design TR so maybe your SR is an earlier production as well

gingertube · 12th April 2012, 07:28 AM

Dick Deviant,
Those 470 Ohm 2W Carbon screen resistors have a bad habit of going open circuit, usually after they have drifted in value (usually high) by as much as 200 or 300 Ohms.

One of the 1st things I do on any Fender is strip out those screen resistors and fit 1K 5 Watt "Rats Coffin" style resistors in their place. This helps protect the output tubes and some claim it gives you a little more "touch responsivity" when playing. I never noticed that but I do think the amp breaks up a little earlier, that is you don't have turn it up quite as loud to get a little power amp compression.

I know that many Fender techs do the same thing.

Cheers,
Ian

Dick Deviant · 12th April 2012, 07:47 AM

Sounds good Ian.
This twin I'm running now sound perfect to me though so I want to keep it stock. If I ever come across a cheap one that is dead or someone else has started modding then I will be very interested in testing out all these little tricks for break up and tone.

All the same thanks for the tip!

8th April 2012, 01:42 PM	#11
doozerdave diyAudio Member Join Date: Feb 2012 Location: Kitchener, Ontario	Glad to hear you found the problem. My silver face Super Reverb has them inside, so I assumed your TR was the same. __________________ -Dave

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8th April 2012, 04:22 PM	#12
Dick Deviant diyAudio Member Join Date: Mar 2012	Cheers! That makes sense. Mine was the final SF design TR so maybe your SR is an earlier production as well

12th April 2012, 07:28 AM	#13
gingertube diyAudio Member Join Date: Oct 2004 Location: Adelaide South Oz	Dick Deviant, Those 470 Ohm 2W Carbon screen resistors have a bad habit of going open circuit, usually after they have drifted in value (usually high) by as much as 200 or 300 Ohms. One of the 1st things I do on any Fender is strip out those screen resistors and fit 1K 5 Watt "Rats Coffin" style resistors in their place. This helps protect the output tubes and some claim it gives you a little more "touch responsivity" when playing. I never noticed that but I do think the amp breaks up a little earlier, that is you don't have turn it up quite as loud to get a little power amp compression. I know that many Fender techs do the same thing. Cheers, Ian

12th April 2012, 07:47 AM	#14
Dick Deviant diyAudio Member Join Date: Mar 2012	Sounds good Ian. This twin I'm running now sound perfect to me though so I want to keep it stock. If I ever come across a cheap one that is dead or someone else has started modding then I will be very interested in testing out all these little tricks for break up and tone. All the same thanks for the tip!