I've got a Thoebe that is technically working, but putting out a lot of extra noise. My Stasis 2's meters stay half-lit throughout it being connected.
I'm going to have a tech recap it, figure out why it is spewing noise, and bypass the tone controls (per Mike B's advice).
I've heard that a TKD volume control fits, but no specifics on which one. Does anyone happen to know?
Also, any other recommended updates (opamps, diodes, etc)?
Thanks!
Jeff
I'm going to have a tech recap it, figure out why it is spewing noise, and bypass the tone controls (per Mike B's advice).
I've heard that a TKD volume control fits, but no specifics on which one. Does anyone happen to know?
Also, any other recommended updates (opamps, diodes, etc)?
Thanks!
Jeff
Hi. Please be careful as less is more in this case - at least from where I stand.
The noise has many causes, from switches that need to be cleaned, resistors that don't have the specs we are used to today, worn out relays... up to aged output devices and most of all: dried solder joints.
Yes - almost all of them.
The tone controls, however, as on all three GAS preamps aren't really the cause.
The volume control is one of the best ever found on a pre - please don't even think of "updating" this. It's not a pot but a fixed resistor switch with a L/R channel accuracy of ±0.5dB even at the first step. A volume control of that quality is hard to find even today.
After recapping it is crucial to readjust the bias voltages - and there's not a lot of people out there who are in the know...so maybe it's a good idea to get in contact with a pro beforehand. Don't just swap caps and turn it on - you will get loads of DC at the outputs unless you carfully adjust everything into specs.
There's no op-amps in THOEBE (and THAEDRA) to be swapped...only in THALIA.
THALIA btw is the one of the three that has virtually no noise at all and sounds best...it's by far the best of the three designs. "Less is more" is the point here also...
The noise has many causes, from switches that need to be cleaned, resistors that don't have the specs we are used to today, worn out relays... up to aged output devices and most of all: dried solder joints.
Yes - almost all of them.
The tone controls, however, as on all three GAS preamps aren't really the cause.
The volume control is one of the best ever found on a pre - please don't even think of "updating" this. It's not a pot but a fixed resistor switch with a L/R channel accuracy of ±0.5dB even at the first step. A volume control of that quality is hard to find even today.
After recapping it is crucial to readjust the bias voltages - and there's not a lot of people out there who are in the know...so maybe it's a good idea to get in contact with a pro beforehand. Don't just swap caps and turn it on - you will get loads of DC at the outputs unless you carfully adjust everything into specs.
There's no op-amps in THOEBE (and THAEDRA) to be swapped...only in THALIA.
THALIA btw is the one of the three that has virtually no noise at all and sounds best...it's by far the best of the three designs. "Less is more" is the point here also...
Thanks for all of the advice! I'm sure the tech will need some time on this one. I'll make sure to ask him about his experience with the GAS preamps.
I don't think that the tone controls are to blame, but I won't use them and, earlier in the thread, Mike Bettinger said they could be bypassed and that would improve the sound.
I don't think that the tone controls are to blame, but I won't use them and, earlier in the thread, Mike Bettinger said they could be bypassed and that would improve the sound.
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Yeah, Mike has been truly helpful on this topic literally for decades, that's for sure.
But nowadys with the whole recapping and mod madness one thing is often forgotten:
When in spec these amps did and still do sound great even without any mod.
Moreover the GAS tone controls are among the most useful ever built on amps, so sometimes with flawed recordings they do come in handy...
Anyway, good luck with your amp, I guess after the process you will like it even more.
But nowadys with the whole recapping and mod madness one thing is often forgotten:
When in spec these amps did and still do sound great even without any mod.
Moreover the GAS tone controls are among the most useful ever built on amps, so sometimes with flawed recordings they do come in handy...
Anyway, good luck with your amp, I guess after the process you will like it even more.
