Well it looks like this is popular. All my extra boards are spoken for. If the there are others who want them I can place another order. Please PM me or post it here. It takes three weeks for me to receive them once ordered.
Blessings, Terry
Blessings, Terry
You should ask Valery for the touched up silk gerbers if you are doing another round.
Yes I thought of that. I think the part numbers are more important that the values.
Blessings, Terry
Blessings, Terry
Hi Valery,
My 0.1R emitter resistors came in today so I just installed them. With the bias as high as it will go I only have 9mV across a pair of resistors. I have it hooked to a Spooky Leach IPS. Here is something I noticed. The Spooky usually puts out about 1.7V per side but plugged into this OPS it only reads .6V on the PD+ and .33V on the ND-. Is there something about this OPS that would draw it down like that? I know the intended IPS is set to 10mA and this Spooky is probably 4.5mA or so.
Suggestions?
Thanks, Terry
My 0.1R emitter resistors came in today so I just installed them. With the bias as high as it will go I only have 9mV across a pair of resistors. I have it hooked to a Spooky Leach IPS. Here is something I noticed. The Spooky usually puts out about 1.7V per side but plugged into this OPS it only reads .6V on the PD+ and .33V on the ND-. Is there something about this OPS that would draw it down like that? I know the intended IPS is set to 10mA and this Spooky is probably 4.5mA or so.
Suggestions?
Thanks, Terry
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Hi Terry,
Just measured my boards. With no signal and zero DC at the output (couple of mV), I have +0.65V at PD+ and -1.2V at ND-. Quiescent current is set in a way that I have 16mV across two 0.1R resistors, giving us 80mA per pair.
For IPS with lower output current you gust need to increase the resistance between PD+ and ND- on OPS board - either increasing R1 value (try some 200R), or purring additional resistor in series with D1 (start with 100R) - I'm referring to OPS schematic from >post #61<.
Cheers,
Valery
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I thought about replacing R1 with a larger trimmer but wanted to be sure it wouldn't hurt anything. I was hoping to be able to used the ops with all of my IPS's. I should receive the parts to finish the TubSuMo IPS today so I'll be able to try that too.
Thanks, Terry
Hi Valery,
I swapped in a 200R trimmer and that did the trick. With 16mV across the emitter resistors I have 110R across the trimmer.
This is a better setup than the 2P slewmaster. It sounds just as good and can take more power. I ran it for two hours into 4 ohms with +-75V rails. My heatsink is too small to have both OPS on it. I needed a small fan blowing on it. I'm liking it a lot.
Waiting for the mailman now for my Mouser order. Should have the IPS running in a few hours.
Blessings, Terry
I swapped in a 200R trimmer and that did the trick. With 16mV across the emitter resistors I have 110R across the trimmer.
This is a better setup than the 2P slewmaster. It sounds just as good and can take more power. I ran it for two hours into 4 ohms with +-75V rails. My heatsink is too small to have both OPS on it. I needed a small fan blowing on it. I'm liking it a lot.
Waiting for the mailman now for my Mouser order. Should have the IPS running in a few hours.
Blessings, Terry
OK, I got it running. First thing I bought some JJ ECC82 tubes. They won't work. D15 & D 17 won't light at all and the offset is really bad. I pulled them and installed one of the Raytheon tubes I used in the low TIM. This works and actually looks really good on the scope until you plug in a load. With a load on it it oscillates. Touching a probe on C26 seems to reduce the oscillation but not eliminate it. Disconnect the load and sine and square waves look really, really good. Up through 20khz the square waves are beautiful. Barely rounded leading edge at 100khz. I really need to get the oscillation resolved because I bet this sucker is going to sound awesome.
Valery is the (other) DIYA wonder.
Seeing that the "kypton" had a rough start 😱 . I'm surprised the lower gain
tube version would oscillate ?
Thimios is about to dive into this topology , I advised him.
Lowering the gain with a "tube equivalent" fet stage, the lack of
capacitance in the Baxandall VAS was eliminated.
This design DOES add C to the baxandall , so any oscillation is a
"unknown" ??
OS
Seeing that the "kypton" had a rough start 😱 . I'm surprised the lower gain
tube version would oscillate ?
Thimios is about to dive into this topology , I advised him.
Lowering the gain with a "tube equivalent" fet stage, the lack of
capacitance in the Baxandall VAS was eliminated.
This design DOES add C to the baxandall , so any oscillation is a
"unknown" ??
OS
This was with the TubSuMo OPS. I will try it with a slewmaster OPS and see if I get the same result.