Salas I measured the unmatched LSK170's I have to use in the power section and I have one that is an outlier, they are supposed to be all A but one looks like either a B or maybe even a C grade (they came from the diyaudio store a couple of years ago). Here are the Idss at 10v:
6.23
5.63
11.08
6.18
6.44
6.35
6.23
5.63
11.08
6.18
6.44
6.35
I wasn't sure if I might be able to use the 11ma one in the position that is tied to the 550/560 collector? I should have checked the parts when I got them but I just put them on the shelf. They all seem to have a C on them but I'm not sure that is a grading mark. I just got a matched B quad from the diyaudio store when I ordered the PCB and they have the same C marking, but they are all 7.2~7.3 mA.
I'll send Elena and email, I may go ahead and order some Toshiba BL ones from punkydawgs on eBay.
I'll send Elena and email, I may go ahead and order some Toshiba BL ones from punkydawgs on eBay.
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Its usable as far as to operate. But now that you know its far away from the others it will always bug you until replaced.
Ok good point and you're right, as much as I think I'm an objectivist I will always wonder "could it be better?"
The rest of the parts should show up today so I'll probably go ahead and stuff the parts I have in to get it going.
I got the shunt supply section running and I'm just waiting on a matched 2SK170-BL quad from punkydawgs for the audio section, they should be here Monday. I ended up using the quad I got from the diyaudio store in the shunt supply along with a couple of other LSK170s with ~6.5ma from the previous diyaudio store "A grade" batch I had. They gave me a credit for the one that was ~11ma Idss and definitely didn't have to since it had been a couple of years.
V+ 9.43v
V- 9.45v
153ma & 158ma (10ohm current resistors)
The input is 28vac under load (24v ct labeled transformer)
V+ 9.43v
V- 9.45v
153ma & 158ma (10ohm current resistors)
The input is 28vac under load (24v ct labeled transformer)
The heat sinks are 36C after 3+ hours running on the bench. I'm not sure I'm going to use them once I get an enclosure since they aren't support by anything but the mosfets - I think they are ok for testing?
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Don't use them in the future, they are big for your CCS setting that is why practically cool, the case's mass will be enough.
For testing they are good because of the clips. TO-247's don't mind some weight, but don't let them bend over while loaded.
What will be the power amplifier's voltage gain? DCB1 needs a sensitive enough amp.
For testing they are good because of the clips. TO-247's don't mind some weight, but don't let them bend over while loaded.
What will be the power amplifier's voltage gain? DCB1 needs a sensitive enough amp.
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An old jfet Hafler SE-100 - way too much gain, ~17 dB. I've reduced the gain to ~6db by changing out the output series/parallel resitors from 316/100K to 16.9k/4.75k.
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