Advice sought about problems with DRRI

jonkay1 · June 9th, 2007, 08:24 PM

My DRRI is about four years old and does get a lot of use. It used to have so much reverb that you didn't have to turn the reverb up past 3. Now I run it at around 5 to 7, and it's just enough. Also, it's developed this really strange harmonic over- ring when you play two string intervals, especially on the higher notes (7th fret or higher on 1st, 2nd or 3rd string.) It's like an unpleasant harmonic distortion behind the notes. I took it to a local store that had a tube tester, and was amazed to find out that all of my pre-amp tubes were bad. The tech said that my rectifier tube was going bad, but he had none on hand. He said the rectifier tube was running very hot, glowing bright red. The 6v6s' were fine. I replaced the preamp tubes, but the problem(s) still remain. He told me that the amp has internal problems, like a bad resistor or something, and gave me the card of a local tube and amp guru and suggested I take it to him. Any observations or comments, advice?
How long should pre-amp tubes last? Isn't odd that all of them were bad?

jjmantele · June 9th, 2007, 08:46 PM

Many tube testers don't provide accurate results for tubes that will be used in guitar amps. Preamp tubes last a long time. The can hum or go microphonic but would normally last much longer than power tubes.

daddyopapa · June 10th, 2007, 10:53 AM

Quote:

Originally Posted by jonkay1

My DRRI is about four years old and does get a lot of use. It used to have so much reverb that you didn't have to turn the reverb up past 3. Now I run it at around 5 to 7, and it's just enough. Also, it's developed this really strange harmonic over- ring when you play two string intervals, especially on the higher notes (7th fret or higher on 1st, 2nd or 3rd string.) It's like an unpleasant harmonic distortion behind the notes. I took it to a local store that had a tube tester, and was amazed to find out that all of my pre-amp tubes were bad. The tech said that my rectifier tube was going bad, but he had none on hand. He said the rectifier tube was running very hot, glowing bright red. The 6v6s' were fine. I replaced the preamp tubes, but the problem(s) still remain. He told me that the amp has internal problems, like a bad resistor or something, and gave me the card of a local tube and amp guru and suggested I take it to him. Any observations or comments, advice?
How long should pre-amp tubes last? Isn't odd that all of them were bad?

Replace the remaining original 12ax7 and 12at7 tubes. JJs are only $7.00 -$9.00 each.

Texasjack · June 10th, 2007, 11:55 AM

I would not think all the preamps would be bad but I would say the 12AT7 in the reverb is susbect . If that rectifier is an original that is Russian or Chinese toss it and get a NOS rectifier . I know they cost but non of the current made rectifiers are very good. Most guys that get a NOS rectifier notice a good improvement in the sound of the amp overall .

June 9th, 2007, 08:24 PM	#1 (permalink)
jonkay1 TDPRI Member Join Date: May 2003 Location: Sacramento, California Posts: 85	Advice sought about problems with DRRI My DRRI is about four years old and does get a lot of use. It used to have so much reverb that you didn't have to turn the reverb up past 3. Now I run it at around 5 to 7, and it's just enough. Also, it's developed this really strange harmonic over- ring when you play two string intervals, especially on the higher notes (7th fret or higher on 1st, 2nd or 3rd string.) It's like an unpleasant harmonic distortion behind the notes. I took it to a local store that had a tube tester, and was amazed to find out that all of my pre-amp tubes were bad. The tech said that my rectifier tube was going bad, but he had none on hand. He said the rectifier tube was running very hot, glowing bright red. The 6v6s' were fine. I replaced the preamp tubes, but the problem(s) still remain. He told me that the amp has internal problems, like a bad resistor or something, and gave me the card of a local tube and amp guru and suggested I take it to him. Any observations or comments, advice? How long should pre-amp tubes last? Isn't odd that all of them were bad?

June 9th, 2007, 08:46 PM	#2 (permalink)
jjmantele Tele-Holic Join Date: Aug 2003 Location: New Jersey Posts: 835	Many tube testers don't provide accurate results for tubes that will be used in guitar amps. Preamp tubes last a long time. The can hum or go microphonic but would normally last much longer than power tubes. __________________ JJman If it says "Vintage" on it -it isn't.

June 10th, 2007, 11:55 AM	#4 (permalink)
Texasjack TDPRI Member Join Date: Jun 2007 Location: Ontario Canada Age: 52 Posts: 22	I would not think all the preamps would be bad but I would say the 12AT7 in the reverb is susbect . If that rectifier is an original that is Russian or Chinese toss it and get a NOS rectifier . I know they cost but non of the current made rectifiers are very good. Most guys that get a NOS rectifier notice a good improvement in the sound of the amp overall .