Both of the plug in boards, MM Phono and Linestage, will be the same as the Thaedra's boards, which boards do you have? The power supply and regulators are on the mother board of which I only have a block diagram, not much detail. PM me with your email and I'll send you what I have.
Craig
Craig
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.
You can replace the green power relay using a standard 12v non-latching relay that's found all over that auction site or from a standard supplier; the only issue is that the form factor is quite different. I used some male-female jumper wires to connect the relay to the the socket -- I could've made a pc board adapter but I'm lazy. Keep in mind that the polarity of the coil connection to the relay is important, and that the NC pins should go to the outside pin points on the socket. I just tucked it away in a safe area and attached it using some automotive trim double-sided tape.
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I own a Gas Thaedra 2. It is originally 120v but I accidentally plugged it into 220v. Anyone with experience please let me know if it can be repaired. Thanks!
If you are lucky only the line fuse blew, check it. If the fuse is good and still no power the power transformer is probably toast. Mercury Magnetics in Chatsworth, CA is the O.E.M. for the xfmr, Sergio may wind a new one for you.
Craig
Craig
Thank you!
I tried removing the cover and smelled something burning. I couldn't find the fuse location. Is it possible that the thaedra doesn't have a fuse? I'm afraid it can damage the rear components. it feels so bad😓😓
I tried removing the cover and smelled something burning. I couldn't find the fuse location. Is it possible that the thaedra doesn't have a fuse? I'm afraid it can damage the rear components. it feels so bad😓😓
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The fuse is on the back next to the power cord. I have a few Thaedras, they all have fuses.
Curious as I couldn't find anything on these online: the E2409 and E6036 FETs: What are they, are they still available, and/or is there a good substitution?
I've searched high and low for those JFET numbers, no luck. I've been using matched quads or octets from the DIYStore, Toshiba 2SJ74 and 2SK170. Expensive but what else can you do? The thing you have to watch out for is the American JFETs swap leads around depending if N or P, the Toshiba pinout is consistant between genders.
Craig
Craig
I don't own one, but the descriptions as to its sound quality had me looking. I figured that J74/K170 would probably be the ideal modern replacements, but pinout as you say could be an issue. Datasheets for the originals would be nice,
If you had the JFET Line Stage board in front of you it's easy to figure out the pinouts. Thoebe uses the same JFET Line Stage but lacks the MC Phono Head Amp. The JFET LS is the magic of these preamps, unfortunately Thaedra II used a completely BJT Line Stage and lost the magic.
Hi IIwhtt.
I have fixed my thaedra. it doesn't have a blown fuse and transformer, it has some broken capacitors on the power board. i have a small question i hope you can answer. my thaedra is very hot, especially on the left side. is this normal? i feel it is hotter than my power mcintosh, even though it consumes very little power. also on the left side of it, i see 2 switches, i don't know what their function is. thank you!
I have fixed my thaedra. it doesn't have a blown fuse and transformer, it has some broken capacitors on the power board. i have a small question i hope you can answer. my thaedra is very hot, especially on the left side. is this normal? i feel it is hotter than my power mcintosh, even though it consumes very little power. also on the left side of it, i see 2 switches, i don't know what their function is. thank you!
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Looking from the front, the board on the right, next to the xfmr cage, is the regulator board, it runs on the warm side. Next to that board is the Line Stage it runs on the warm side also. You should have approx. 1.8VDC across the big 30 Ohm resistors for 60ma. Thaedra I runs at 100ma so the Thaedra II is bit cooler. The switches on the left side of the preamp are for selecting the gain of the MC Head Amp.
Do you need/what schematics for the Thaedra II, I have all of them.
Do you need/what schematics for the Thaedra II, I have all of them.
thank you very much! maybe i just need the schematic of Thaedra 2, can you please send it to me?
I had both Theadra and still have a Thoebe. Both had Noble potentiometers. The Nobles are very good pots but if you are having issues with it and can't find replacement, then try the TKD pots. I have been using the TKD pot since early 2000 and never had any issue with them, best pot of have used. One thing you may miss is the indentations (clicking) on the Volume pot of the Nobles in the Thoebe, the TKD doesn't have that be very smooth and firm feeling.
btw, have you replaced the output Transistors on the Thoebe? Mine went out on my Theadra and passed -7Vdc to may amp and freaking messed up the amp. I had the Theadra fixed but got rid of it after that. It cost me a lot to ship my amp back to the manufacturer to replaced all the burned out transistors in the amp. It did sound nice up til that happened.