DIY Class A/B Amp The "Wolverine" build thread

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#1,243
poseidonsvoice said:
Stuart,

Although I am able to order (ie "add to cart") the Ground Lift PCB, for some reason when I try to add the T-GND pcb to the cart it doesn't show up, there is an error. Can you double check with pcbway and see what is going on?

Thanks,
Anand.
Click to expand...
You may just have to wait a hour or so until they complete there audits.
Then you should be able to check out.
 

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#1,244
@stuartmp

Want to publicly thank you for the Ground Lift and T-GND pcb designs. As simple as they are, they are a necessity. They ease the burden of implementing star ground and ground fault schemes into my existing designs.

I ordered 10 boards each, in blue, since that’s my favorite color! I’ll likely use all of them…eventually 😉.

Regards,
Anand.
 
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#1,245
javaught said:
After selecting my rail voltage (64V) I now realize I need to find some suitable capacitors for the power supply. I’m planning on using the diyAudio store Universal Power Supply Board. I am finding few if any options for 80V+ 35mm diameter caps. Does anyone at this rail voltage or higher going with a linear power supply have a suggestion for some suitable capacitors.
Click to expand...
https://www.mouser.com/c/passive-co...ts/capacitors|~Termination Style|~Capacitance

This brings up the mouser entries for 10mF + at 80v, 35mm. As you can see, there are lead times for most of these caps. The KEMET "audio grade" that claims 15000 hours does not give a ripple current rating and so I think this is not a suitable power supply capacitor. You could try the Nippon Chemicon caps, but I have no long term experience with them. Your problem is the 35mm restriction. That is small for large caps in the 80+ voltage range.
 
#1,246
A question about the VAS transistor: I have a supply of the KSC3503Ds, which measure around 84 Hfe on my SFB tester - 88 being the highest I found out of 20 I measured. I also have KSC2690As which measure at around 275 Hfe. The 2690 has about 15 times the output capacitance and the Hfe is not as linear as the 3503 with a much lower Early voltage from what I can tell from the abbreviated graph. What is most important for the VAS -beta or linearity and low capacitance? I'd think that the 3503Ds would be the way to go. I realize there are some Es available from other members, but I'm sure I cannot hear the difference between 0.5 ppm and 1.0 ppm distortion.
 
#1,250
hi,
what do you think about using wirewound resistors in EF3-3 output stage?
I have 1W 1Ohm 1% PAC100001008FA1000 (R112, R113)
and
3W 20Ohm 1% UB3C-20RF1 (R126,R127 ab)

PAC100001008FA1000 measured inductance out of three samples:
10kHz: 0.1-0.12uH
100kHz: 0.13-0.15uH


UB3C-20RF1 measured inductance out of three samples:
10kHz: 0.3-0.36uH
100kHz: 0.31-0.32uH


for comparison 5083nw20r00j
10kHz: 0.14uH
100kHz: 0.044uH
 
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