2ch dual rectifier volume dropping out

[RonFromOhio]

I have an old 2ch dual recto, recently it started to sound quiet and muddy at a higher volume so i replaced the 2 EL34's i had in it with 2 of the 6L6's that were in it originally, and i swapped out the installed rectifier tube also just for good measure. Problem disappeared, sounded great again (even though I prefer EL34's, I just didnt have any spares).

I am running half the power tubes to make it break up sooner.


For some reason after about an hour of practice this week my amp started to seem like it was not as loud as it was earlier in the evening. It seems like I am losing volume.


I have never had an OT go out before so I dont know what it does when its starting to fail, is there any advice anyone can give me on how to go about troubleshooting, or what kind of problems this could be a symptom of?


Thanks in advance,

 

[YellowJacket]

Have you checked your preamp tubes yet? I had a similar problem and I discovered it was the v1 preamp tube. I replaced it with a Tung Sol 12ax7 and my tone has been crushing ever since.
V3 was also acting up so I swapped it for a mesa badged 12ax7.

 

[RonFromOhio]

Have you checked your preamp tubes yet? I had a similar problem and I discovered it was the v1 preamp tube. I replaced it with a Tung Sol 12ax7 and my tone has been crushing ever since.
V3 was also acting up so I swapped it for a mesa badged 12ax7.

I have not replaced any preamp tubes, I didn't think it would cause a loss of volume. Can it?

 

[SigiZ58]

Did you check if the Volume drop happens on both channels or only on one ?

 

[LesPaul70]

I have not replaced any preamp tubes, I didn't think it would cause a loss of volume. Can it?

Oh yes they can, if it is a Russian made preamp tube in a cathode follower position. This is a known issue, and has been mentioned in the FAQ:
http://forum.grailtone.com/viewtopic.php?f=24&t=54097 (the fourth question)

For a more detailed explanation, see:
http://forum.grailtone.com/viewtopic.php?f=24&t=31075&p=228953#p228953