Tourmaster problems, please help

[LaXu]

Some time ago my Tourmaster 4100 head started crapping out on me. When I took it off standby it'd make this "pop! skooosssssshhhhhhh" sound and then the volume would be way too low and might drop out altogether. At first turning off the amp a few times seemed to fix it but after that I always got the weird sound and eventually no output at all. Tried the preamp tubes and it was the effects loop tube that had apparently malfunctioned. Replaced the stock tube with a spare Ruby branded JJ ECC83S.

All was fine for some time, but now I'm getting that damn problem again! This time I again went thru all the tubes one by one but it didn't go away. I ended up grabbing some spare preamp tubes and some tubes out of my Diezel and replaced every tube with the assortment of 12AX7s I had (JJ ECC83S, JJ ECC803S, Svetlana/SED 12AX7, EH 12AX7, GT 12AX7M...). This took out the sound, but still really low output even though I have the master at 9 o'clock at home, which usually is just fine for volume.

I opened up the amp but since I'm no tech I can't tell anything other than that there seemed to be no loose connectors or blown components as far as I can tell. I also checked the bias, it was at the recommended 120 mVDC. Then I decided to see if it was the poweramp that was acting up: I connected the fx loop send on the Egnater to the fx loop return on my Diezel Einstein combo and behold, sounded just fine, even when I put back the stock preamp tubes (except the one that had broken before). With the stock tubes I do get some of that "pop! kosshh" though so maybe one of them is going too..

Anyway, now it looks like something's up with the poweramp. I don't have a quartet of 5881 or 6L6GC tubes available, but I do have a matched pair of Svetlana/SED "Winged C" 6L6GCs. Can I use these tubes to test the poweramp? If yes, which slots should I put them in?

 

[bruce egnater]

Contact Nate at nate@egnateramps.com or phone him at 1-877-egnater. He will help you right away. FYI, if the power tube bias setting is correct, not likely it is a power tube problem. Did you try replacing the 12aX7 that is right next to (in line) with the power tubes? Also the effects loop tube.

 

[Anonymous]

It sounds to me like a poweramp tube problem! If it's just dropping out like that...

If you have only the 3, use only the 2 poweramp tubes.


Put them in either the 2 OUTSIDE, or both INSIDE. Now before you do this, what cab are you hooking into? You are going to have to adjust for ohms...report back.

 

[LaXu]

Contact Nate at nate@egnateramps.com or phone him at 1-877-egnater. He will help you right away. FYI, if the power tube bias setting is correct, not likely it is a power tube problem. Did you try replacing the 12aX7 that is right next to (in line) with the power tubes? Also the effects loop tube.

Thanks for the quick reply. Already sent him a message before posting here, but since it's Sunday I figured I might get answers faster here.

I replaced both the phase splitter and effects loop tube (V8 and V7 according to the manual). Still get a slight "skoohshh" when coming off standby and even if I turn the master volume to noon (with channel volumes at noon to 2 o'clock), the volume is still pretty much bedroom volume. Changing any of the Power Grid options or the half power switch doesnt' help.

japetus: It's a 4 ohm 2x12 cab so the amp is already set to the minimum 4 ohm setting. I know you're supposed to halve the impedance when running only on two tubes.

 

[LaXu]

Did some more testing. I put the Egnater's power tubes into my Diezel head (one pair at a time since it's a 50 watter), set bias and both pairs worked perfectly fine so the power tubes are ok.

Then I just installed the tubes back in and made sure all preamp tubes were pushed all the way in. This seems to have restored some of the volume, but it's still noticeably quieter than it used to be. With ch volume at 2 o'clock on overdrive 1 in modern mode, gain at 2 o'clock and master at 9 o'clock it's nowhere near as loud as my Diezel with master at 8 o'clock and ch volume at noon with similar gain levels. Granted, the Diezel's MV is more touchy but these settings used to be about as loud.