One had already gone south and I had replaced it with a working tube from another amp although I should have replaced them as a matched pair. Life got busy and I completely forgot about the state of the power tubes until rehearsal yesterday.
Something was not right.
The amp suddenly changed. Loss of dynamics or headroom. And early onset of distortion. Again, without headroom. The rig no longer responded as expected.
I made a few onboard changes. I significantly reduced the Fulltone OCD overdrive settings. I made sure the Tim was only adding a bit of sparkle. I also turned up the input volume on the amp as the rig also exhibited loss of volume.
This all happened about 40 minutes before downbeat.
Lorraine was kind enough to head home and pick up my Dr. Z Maz Senior head. Always good to have backup on the ready. Funny, the Dr. Z is a great sounding amp but not as sophisticated to my ear as the Swart AST Mk II. When I plugged it in, I really missed my tone from the Swart.
I decided to risk running the Swart and it did make it in one piece. The guitar sound was a lot more “distorted” than normal but stayed within the general sweet spot and likely only noticeable to my ear.
I placed an order for a new set of tubes from the tube store in Hamilton. The tubes should arrive sometime over the next couple of days.
I ordered the following:
- 3 x 12 AX7: JJ ECC83-S
- 1 x 12DW7: JJ 12DW7 / ECC832
- Matched pair 6v6: Tung-Sol 6V6GT TS-6V6
- Rectifier: JJ GZ34 / 5AR4 TE-5AR4
I had received the Swart amp in May of 2010. Generally, an amp that gets a fair amount of use should replace the power tubes at least once a year. I carry some spare tubes with me but I should have re-tubed when the first power tube failed a few months back. My bad.