Channel 1 volume, gain issues

[delt4]

I've noticed on my Mark V head that I have less volume on channel 1. Normally I have all my channel volumes about 9 to 10 o'clock ish, about quarter of a way up. Channel 1 used to be very loud at 9 o'clock, that I had to turn it down lower than channels 2 and 3. Now I need to keep my channel 1 volume about noon and even then it's barely louder than channels 2 and 3. I've also noticed a considerable lack of gain and saturation from channels 2 and 3. Channel 3 on Mark iv mode's gain almost sounds like a jcm800 gain wise and thats with the gain nearly maxed on channel 3.

I've looked at the power tubes in the back. The 4 6L6s' are glowing normally. I also saw the 5U4G tube does not have a glow on top as compared to the 6L6 tubes. Is this normal?

Anything else I should check?

 

[Nicklotsaguitars]

Well you can rule out your rectifier valve by switching to diode rectification and seeing if the problem persists. I think it will.
It sounds to me like a pre-amp valve, not a power valve. Perhaps the 2nd half of V1 has gone, if you're only noticing problems on channels 1 and 3

 

[delt4]

Ok, thanks for the response, will check that out.

 

[fr0sty]

Are you running your channels in 45 watt mode? If so, using the tube rectifier give a lower volume than diode rectifier and that can contribute to channel one being quieter.

 

[delt4]

Fr0sty, yes, I'm running in 45 watt. However, I never had the issue with the volume drop and gain before in 45 watt mode??

 

[Nicklotsaguitars]

I could be wrong but if the rectifier fails doesn't the amp automatically switch to the other rectifier?

That wouldn't be causing a channel specific volume drop anyway. What the rectifier valve does is to sort the AC power out to DC power for the other valves heaters. It operates across the board. Aside from channel 3. So if it was that you'd hear the problem on channels 1&2 but channel 3 would be fine because it automatically selects diode rectification.

 

[fr0sty]

I would check to be sure both channel 1 and 2 are set to the same rectifier mode (either both tube or both diode) just to be sure.

Fr0sty, yes, I'm running in 45 watt. However, I never had the issue with the volume drop and gain before in 45 watt mode??

 

[delt4]

All channels are running in 45 watt mode. Channel 1 and 2 in diode mode and channel 3 in Pentode.

 

[fr0sty]

Next step I would take would be installing a new set of power tubes.

 

[Nicklotsaguitars]

It's really not output valves. The problem would be across the board if that were the case.
And if you're constantly running at 45watts. Then simply swap the inner pair for the outer pair, as they'll be unused.
Swap V1 for V7. Trust me, the gain issue is way more likely to be V1. Take a look at the back of your handbook. See what it governs. It won't make any difference by putting it in the phase inverter

 

[delt4]

I was thinking about the power tubes, wouldn't hurt to swap out inner pair with outer pair, if anything to see if that changes anything.

As for the V1 and V7 tubes, I'll see what happens.

Thanks all so far!