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1968 Deluxe Reverb

Kmaz

Silver Supporting Member
Messages
8,980
I have a Silverface model and the reverb sounds a little weak. Likely a preamp tube wearing out?
 

guitar007

Member
Messages
443
Assuming it's the amp...start swapping out your preamp tubes...then power tubes until your amp sounds like it should.
 

bob-i

Member
Messages
8,763
The tubes would be my first test, followed by the leads. I've never had a weak tank myself but it's possible.
 

Kmaz

Silver Supporting Member
Messages
8,980
Check the tubes in V3 and V4 (reverb driver and return respectively). Check the RCA cables. Check the pan to see if that little plastic piece is broken. If none of that works, check the reverb transformer.

But probably a tube, the rca cable, or the pan.
Thanks, guys. Care to recommend a good V3 or V4? I've probably got Electro Harmonix in there right now. I think that's the name? :)
 

dcbc

Member
Messages
2,310
Another EH tube will work fine. That's what David Allen used when he worked on mine V3 is 12AT7; V4 is 7025 (12ax7). You get the most bang for the buck with the NOS type American preamp tubes in V1 (assuming you play on the vibro channel.
 

calfzilla

Cynical Hack
Messages
3,865
Thanks, guys. Care to recommend a good V3 or V4? I've probably got Electro Harmonix in there right now. I think that's the name? :)
Jan Phillips 12AT7WC are typically loved for reverb driver spots. NOS, military spec, and can be had CHEAP. Like $15 a tube shipped from a supplier. Can't really beat it.
 

tmac

Goldmember
Platinum Supporting Member
Messages
2,248
Jan Phillips 12AT7WC are typically loved for reverb driver spots. NOS, military spec, and can be had CHEAP. Like $15 a tube shipped from a supplier. Can't really beat it.
Yes, these are good, and rugged in this position, a silverface Fender amp can run a 12at-7 pretty hard depending on the cathode resistor. Some as low as 470 ohms.
 

Boomstick

Member
Messages
313
Assuming it's the amp...start swapping out your preamp tubes...then power tubes until your amp sounds like it should.
Don't forget to get it rebiased when you change power tubes, and possibly re-capped too, it's old enough where it'd need it.
 

Boomstick

Member
Messages
313
Thanks, guys. Care to recommend a good V3 or V4? I've probably got Electro Harmonix in there right now. I think that's the name? :)
Electro Harmonix makes some of the best current preamp tubes on the market. Much better than Chinese/JJ/Sovtek etc. The new Mullards are a little better and the Genelex RI's are close, but it's in the top tier in terms of definition and tone balance. But it's possible if it's old enough it may be near the end of its life too.
 

Tone Meister

Member
Messages
3,266
Check the tubes in V3 (12AT7) and V4 (12AX7) (reverb driver and return respectively). Check the RCA cables. Check the pan to see if that little plastic piece is broken. If none of that works, check the reverb transformer.

But probably a tube, the rca cable, or the pan.

THIS ^^^^
 

Boomstick

Member
Messages
313
Really?

Those are all tubes from the exact same company and made at the same factory. Some are even the exact same tube (for instance, the Sovtek 12AX7LPS = 12AX7EH)
Well, first I see you completely edited and bastardized the quote. I hope it was unintentional and you aren't intentionally trying to troll me but I never said the Eh's were much better than them, ever. As I said, the Mullard RI's are a little better than the EH's (made by EH, as are the Genelex RIs). I should note the Sovtek 12AX7LPS is a pretty decent tube overall but the rest of the Sovtek branded tubes aren't fantastic. and I've never used a 12AX7-EH but you can tell by looking at it that it is not the same tube the plates are a different size even.
 
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Blue Strat

Member
Messages
30,241
Really?

Those are all tubes from the exact same company and made at the same factory. Some are even the exact same tube (for instance, the Sovtek 12AX7LPS = 12AX7EH)
Yes, kinda...except that the LPS is NOT the same as the EH...not even visually. The plates on the LP (long plate) are...ummm, long. The EH plates are not.
 

Boomstick

Member
Messages
313
Certainly. My comment is pertaining to early troubleshooting.
I just always mention that when I don't see it mentioned for those who are less experience with tube amp ownership. Some people have no idea you can't hot swap them (except on self-biasing cathode amps).
 






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