Hello Cody, Papa advices towards R18=0 with the Semisouth. I read you implemented that too afterwards... I understand you came back to a small R18 in the end, but can you share the other alternations needed in combination with R18=0 to get the right H2 please?
I install pin sockets for the source resistors, so swapping different values in and out is no problem. I’m not sure I’ve settled on just one combo yet. I believe I had good results with 0R on bottom and .07R on top. That also required a change to R24, the resistor that determines the amount of AC loopback the Aleph current source sees. Stock value is 1K2, and I believe I was at 1K4 with the above combo. Nelson’s has mentioned the the goal was to see around a 50% AC contribution from the modulated current source. I believe the Zen3 write-up includes instructions if you’d like to measure that data point.
I should also note that - at these small, incremental values - variations in the output parts themselves play a big role. Without some way to measure distortion, its hard to know for sure what you’ll end up with. For instance, a change as small as .1R can completely shift the harmonic cancellation; you could quickly end up with 2nd harmonic cancelled considerably and a more even distribution of H2 and H3 dominant amp (which still sounds fantastic). If you have a way to measure the distortion, it’s wise to set some sort of target to shoot for. Or, try several variations and see what you like best.
All in all, a long-winded way of saying it’s hard to prescribe a set of values and be sure you’ll get the same results as me. Ought to get you close though 🙂
I should also note that - at these small, incremental values - variations in the output parts themselves play a big role. Without some way to measure distortion, its hard to know for sure what you’ll end up with. For instance, a change as small as .1R can completely shift the harmonic cancellation; you could quickly end up with 2nd harmonic cancelled considerably and a more even distribution of H2 and H3 dominant amp (which still sounds fantastic). If you have a way to measure the distortion, it’s wise to set some sort of target to shoot for. Or, try several variations and see what you like best.
All in all, a long-winded way of saying it’s hard to prescribe a set of values and be sure you’ll get the same results as me. Ought to get you close though 🙂
A few quotes slowly moving from technical part to Cody sound impressions of SS in Aleph J.
Maybe you will find that interesting.
Hello all - PCB's arrived yesterday.
I the following people down for J2 boards. I made 15 pairs of EUVL's J2 V2 board. I also made some from mighty ZM's gerbers. I made extras assuming there might be a few who want to try the J2 circuit. Here's who I have down:
CodyT + bridge boards + beta test PSU PCB
Elwood625 + 3 bridge board pairs + beta test PSU PCB
pfdavid + 2 bridge board pairs + beta test PSU PCB
Jasonb84
Ylab (Hubert)
Note: I understand from 6L6 these are NOT aligned to the UMS standard. so you'll need to do some drilling and tapping.
Let me know via PM which boards you want, your shipping info, and paypal email. I'll tally up my actual cost for the PCB's you want + shipping.
Boards are:
EUVL J2 PCB pair (bottom left). ZM J2 PCB pair (bottom right). Bridge/snubber PCB pair. CL-60/AC Cap PCB. Dual Rail PSU PCB (no charge - see beta test thread).
Once I have the above info, I'll ask that you please paypal my cost + shipping + any extra you're kind enough to add. Please use the paypal "friends and family" option so additional fees aren't taken out.
I the following people down for J2 boards. I made 15 pairs of EUVL's J2 V2 board. I also made some from mighty ZM's gerbers. I made extras assuming there might be a few who want to try the J2 circuit. Here's who I have down:
CodyT + bridge boards + beta test PSU PCB
Elwood625 + 3 bridge board pairs + beta test PSU PCB
pfdavid + 2 bridge board pairs + beta test PSU PCB
Jasonb84
Ylab (Hubert)
Note: I understand from 6L6 these are NOT aligned to the UMS standard. so you'll need to do some drilling and tapping.
Let me know via PM which boards you want, your shipping info, and paypal email. I'll tally up my actual cost for the PCB's you want + shipping.
Boards are:
EUVL J2 PCB pair (bottom left). ZM J2 PCB pair (bottom right). Bridge/snubber PCB pair. CL-60/AC Cap PCB. Dual Rail PSU PCB (no charge - see beta test thread).
Once I have the above info, I'll ask that you please paypal my cost + shipping + any extra you're kind enough to add. Please use the paypal "friends and family" option so additional fees aren't taken out.
Attachments
Randy,
The boards look great and I know the quality is first class. I wish I had more time to build them. Maybe in the future.
The boards look great and I know the quality is first class. I wish I had more time to build them. Maybe in the future.
Hi Cody,
The SemiSouths have arrived today, Yipieee ! 🙂
Thanks Pass & Cody !
I've played a little with the Aleph J SS from a few posts back.
Looks nice, but to get a good opposite current phase of the traces I(R16) and I(R18) I had to lower the CCS FB resistor R24 to 750R
One problem I have in Ltspice is the low gain at the output, in fact there is no gain, it acts as a buffer 😕
Do you have an idea?
Danny
The SemiSouths have arrived today, Yipieee ! 🙂
Thanks Pass & Cody !
I've played a little with the Aleph J SS from a few posts back.
Looks nice, but to get a good opposite current phase of the traces I(R16) and I(R18) I had to lower the CCS FB resistor R24 to 750R
One problem I have in Ltspice is the low gain at the output, in fact there is no gain, it acts as a buffer 😕
Do you have an idea?
Danny
Attachments
I can’t remember how C2 is hooked up, so you might double check that. Otherwise it looks spot on to me. Regarding R24 - I’ve noticed that small changes here make a big impact. I’ve never implemented anything less than 1K, not any higher than 1.5K. I recently made some AJ/SS boards and I used a pot here. It’s been very fun to twist the setting and watch the impact it has on distortion, etc.
My F2J with the very generously provided SS JFETs is just about done. I finished all the boards and mounted them in the chassis. Just need to wire it and test it. So close to the finish line.
Thanks again codyt and Mr. Pass.
Thanks again codyt and Mr. Pass.
Hi Cody,
I just noticed you have R9 & R11 at 100ohms as apposed to the original values of
221ohm. In the many tests you’ve done would there be any harm to leaving R9/11 at the original values with R16/18 now at .22 ohms? Just getting my parts together and noticed the different values.
Thanks
No problem at all to leave them at the original value. I doubt you'd see any consequential performance improvements by lowering them. I believe I did just because I'd seen in done with other designs.