I think you will find the R100's in the F8, not the cheapest way to get them.
In the J2 you can use the IRFP240 and similar in the mu follower, and
using them in both spots you can still get quite a good amplifier.
I continue to look for parts that are comparable to the R100, R085, and
needless to say, the SIT-1.
In the J2 you can use the IRFP240 and similar in the mu follower, and
using them in both spots you can still get quite a good amplifier.
I continue to look for parts that are comparable to the R100, R085, and
needless to say, the SIT-1.
I think you will find the R100's in the F8,
aw shucks.... hey, it was wishful thinking!
Need a little help from my friends... What case did you use for your J2 builds? I'm starting the build on one soon and would like some ideas. Since Pappa doesn't mind/tolerates cases from pretty much anywhere, as long as it isn't a blatant attempt to deceive with regards to his commercial amp and intellectual property, all sources welcome as long any badging doesn't have Nelsons' name on it.
Thanks for any help you may give.
JT
Thanks for any help you may give.
JT
Check the power dissipation of the store 4U 400mm heatsinks, that's what I would suggest as a minimum for long term reliability.
My Protos
Referring to the schematics posted at #1274.
https://www.diyaudio.com/forums/att...50-firstwatt-j2-j2-clone-k3497-sch-public-pdf
Both channels worked first time as intended.
10kHz square wave has smooth rise and fall without ringing.
More to come after finishing final wiring.
Power supply is regulated LT1085/LT1033 followed by XEN cap multiplier.
Rails at +/-20V, bias 1.6A for more driving capability for 4~6 ohm load.
Patrick
.
Referring to the schematics posted at #1274.
https://www.diyaudio.com/forums/att...50-firstwatt-j2-j2-clone-k3497-sch-public-pdf
Both channels worked first time as intended.
10kHz square wave has smooth rise and fall without ringing.
More to come after finishing final wiring.
Power supply is regulated LT1085/LT1033 followed by XEN cap multiplier.
Rails at +/-20V, bias 1.6A for more driving capability for 4~6 ohm load.
Patrick
.
Attachments
Very nice! Did you modify your boards to accept SMD resistors? I see you have banks of paralleled/series resistors in place of the parallel 3W. Are the rectifiers in the middle tunnel?
> Did you modify your boards to accept SMD resistors?
There is a public version and a private version.
Public Version has no logo, etc.
> I see you have banks of paralleled/series resistors in place of the parallel 3W.
I wanted to use 4x MELF 0207 thin film instead of 2W metal oxide.
> Are the rectifiers in the middle tunnel ?
Among other things, yes.
Tx is Plitron 300VA 2x18Vac. Diodes are MSR860.
Also included is XEN SPP speaker protection.
Patrick
There is a public version and a private version.
Public Version has no logo, etc.
> I see you have banks of paralleled/series resistors in place of the parallel 3W.
I wanted to use 4x MELF 0207 thin film instead of 2W metal oxide.
> Are the rectifiers in the middle tunnel ?
Among other things, yes.
Tx is Plitron 300VA 2x18Vac. Diodes are MSR860.
Also included is XEN SPP speaker protection.
Patrick
Question: Do we need the source resistors R15 and R16 under Q5 or could they possibly be omitted to avoid local degeneration?
> Do we need the source resistors R15 and R16 under Q5
> or could they possibly be omitted to avoid local degeneration?
I have not tried without, but go ahead and try for yourself.
Patrick
> or could they possibly be omitted to avoid local degeneration?
I have not tried without, but go ahead and try for yourself.
Patrick
Thank you for the quick answer. That's what I am planning to do, though I keep procrastinating. I just thought I might have overlooked something and the source resistors HAD to be there.
Note how the AC part of the power supply is shielded from the amplifier circuits by the case layout.
Patrick
Patrick