Hi there.
Long story:
I have a Randall Diavlo RD100H with stock Ruby pre-amp (12AX7) and power amp (6L6) valves.
A few days back, it made a single sharp popping sound for less than a second that exceeded the general volume the amp was set at, though nothing else went wrong and everything appeared to be working fine. Then day before yesterday, another sharp popping noise took place but accompanying what appeared to be a momentary flash in the second power valve, at least that's what I think I saw from the corner of my vision. It didn't repeat again. What I did notice after this was that the amp's master volume seemed a little less sensitive, which was odd because as a 100 watt head, it can be very loud early on in the dial, which it wasn't quite doing any longer. I also noticed that the valves, which were always emitting that blue glow (for as long as I've had the amp) every time the amp would be taken out of standby, were acting differently. Only the two of the valves in the centre were emitting the blue glow while the other two just weren't showing any response to the standby switch. The filaments were lit up as usual, but that's about it.
For the sake of confirming if this was an issue with the valves, I swapped them around, and upon turning it on, noticed the second valve very clearly flash sharply while the speaker emitted a similarly sharp popping noise the ones from earlier days. This time, none of the valves were emitting the blue glow, while the filaments were still lit. Also, the amplifier was completely silent, no basic noise or even a hiss. I put the valves back into their original positions, and the issue persists. It just doesn't seem to be outputting any sound from the cabinet. Only when I really crank up the volume, at certain points, one can hear a very faint and subdued bit of distortion, almost undetectable.
Also, I gave the XLR output with its own built-in cabinet emulation a try by plugging it into a computer's audio interface. In this mode, it's meant to just send the pre-amp signal directly with said cabinet simulation to the interface. This appeared to be working fine as per usual. So, the issue seems specific to the power section and valves.
Short story:
Amp was making strange but brief popping noise. Power valves flashed and then stopped producing any sound via cabinet while the amp is powering up, the filaments lighting up and the pre-amp section working as confirmed by the XLR output via computer interface.
I am curious to know what's going on here. Happy to send it to a technician, but before I do, I was wondering if there are any other trouble shooting methods I can employ shy of fully opening up the amplifier because I'm not well-versed in that area nor do I have the appropriate equipment. Would getting a new set of matched valves help? Or do I risk damaging them or the amplifier just from a simple swap and a brief test (I intend on sending it off for biasing after)?
Thanks.
Long story:
I have a Randall Diavlo RD100H with stock Ruby pre-amp (12AX7) and power amp (6L6) valves.
A few days back, it made a single sharp popping sound for less than a second that exceeded the general volume the amp was set at, though nothing else went wrong and everything appeared to be working fine. Then day before yesterday, another sharp popping noise took place but accompanying what appeared to be a momentary flash in the second power valve, at least that's what I think I saw from the corner of my vision. It didn't repeat again. What I did notice after this was that the amp's master volume seemed a little less sensitive, which was odd because as a 100 watt head, it can be very loud early on in the dial, which it wasn't quite doing any longer. I also noticed that the valves, which were always emitting that blue glow (for as long as I've had the amp) every time the amp would be taken out of standby, were acting differently. Only the two of the valves in the centre were emitting the blue glow while the other two just weren't showing any response to the standby switch. The filaments were lit up as usual, but that's about it.
For the sake of confirming if this was an issue with the valves, I swapped them around, and upon turning it on, noticed the second valve very clearly flash sharply while the speaker emitted a similarly sharp popping noise the ones from earlier days. This time, none of the valves were emitting the blue glow, while the filaments were still lit. Also, the amplifier was completely silent, no basic noise or even a hiss. I put the valves back into their original positions, and the issue persists. It just doesn't seem to be outputting any sound from the cabinet. Only when I really crank up the volume, at certain points, one can hear a very faint and subdued bit of distortion, almost undetectable.
Also, I gave the XLR output with its own built-in cabinet emulation a try by plugging it into a computer's audio interface. In this mode, it's meant to just send the pre-amp signal directly with said cabinet simulation to the interface. This appeared to be working fine as per usual. So, the issue seems specific to the power section and valves.
Short story:
Amp was making strange but brief popping noise. Power valves flashed and then stopped producing any sound via cabinet while the amp is powering up, the filaments lighting up and the pre-amp section working as confirmed by the XLR output via computer interface.
I am curious to know what's going on here. Happy to send it to a technician, but before I do, I was wondering if there are any other trouble shooting methods I can employ shy of fully opening up the amplifier because I'm not well-versed in that area nor do I have the appropriate equipment. Would getting a new set of matched valves help? Or do I risk damaging them or the amplifier just from a simple swap and a brief test (I intend on sending it off for biasing after)?
Thanks.