Channel 4 problem with my Roadster...

[KH Guitar Freak]

I just noticed this morning that channel 4 on my Roadster has a substantially permanent drop in gain, but especially in volume. I initially thought it might be preamp valve related, but if it was, channel 3 would be affected as well. Channel 1, 2, and 3 on my Roadster works just fine. The problem also seems to be affecting all 3 modes on channel 4. Anyone ever experience a same/similar problem as I do with mine???

 

[KH Guitar Freak]

Update: Got my amp back from the authorised repairer here in Perth, Western Australia. Turns out it's a bleeding treble pot on channel 4. Basically a lot of the signal is being grounded to the chassis, hence the loss of volume I had experienced before getting it repaired. Too bad it's out of warranty. My pocket is AUD 145.20 less... :?

 

[Holy Diver]

At least it's sorted...

 

[KH Guitar Freak]

At least it's sorted...

I guess. My wallet is lighter now... :lol:

 

[brich]

Did the problem come and go or was is present at all times once it started happening. My single rectifier is doing something similar, but it goes back and forth from working fine to having the problem. This just started around a week ago. I changed all of the pre amp and power tubes, but that did not fix it. I am going to take it to the repair shop this week and am doing some research to try to pass info on to the repair guy.

The gain/volume drops significantly to a very weak signal and you mainly hear treble and no bass at all when it cuts out.
Power the amp off and on a few times and it starts working fine for a while. Then it flakes out again....

 

[KH Guitar Freak]

Did the problem come and go or was is present at all times once it started happening. My single rectifier is doing something similar, but it goes back and forth from working fine to having the problem. This just started around a week ago. I changed all of the pre amp and power tubes, but that did not fix it. I am going to take it to the repair shop this week and am doing some research to try to pass info on to the repair guy.

The gain/volume drops significantly to a very weak signal and you mainly hear treble and no bass at all when it cuts out.
Power the amp off and on a few times and it starts working fine for a while. Then it flakes out again....

Mine was a permanent loss in gain and volume. Said gain and volume does not fluctuate, nor does the problem go away regardless of what you do...

 

[domct203]

Did the problem come and go or was is present at all times once it started happening. My single rectifier is doing something similar, but it goes back and forth from working fine to having the problem. This just started around a week ago. I changed all of the pre amp and power tubes, but that did not fix it. I am going to take it to the repair shop this week and am doing some research to try to pass info on to the repair guy.

The gain/volume drops significantly to a very weak signal and you mainly hear treble and no bass at all when it cuts out.
Power the amp off and on a few times and it starts working fine for a while. Then it flakes out again....

Have a read here, hope it helps.

http://forum.grailtone.com/viewtopic.php?f=4&t=25102&start=19

Dom

 

[brich]

Dom, thanks for the link....great info. I will get my hands on some Chinese tubes and try them. I have been having the SPAX7-A tubes in there and my backup tubes are Russian 12AX7. I am having the problem with both. Do you or anyone else know where the SPAX7-A tubes are from? I know these are the ones that MESA picks out of the batches as better tubes.