The technical discussion thread for the ALPHA amp is here:
Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Thank you AKSA for design and inspiration, JPS64 for layout, and Nelson pass for Aleph CCS!
This is a spin-off from the above thread to keep discussions to the group buy and the build process separate.
Schematic for 20W ALPHA:
Parts placement:
3D render:
Example build with Vishay-Dale/Wima/Silmics:
Another example with non-premium resistors:
Alpha 20 with 1.31amp bias and 2.86vrms into 8ohms gives 0.0069% THD, 0.0059% if using all Vishay-Dale:
BOM and Schematics here (note that there is error on R108, should be 47R not 470R, and for R131 and R132, use Pan ERX 3W 0.47R and 0.22R, respectively for 1.35 amp bias:
http://www.diyaudio.com/forums/soli...rid-aleph-alpha-amplifier-51.html#post5348523
Corrections to previous BOM in BOLD
ALPHA 20 Group Buy PCBs are $28/pair with $5 shipping to USA, $10 to Canda, and $15 everywhere else.
Current list of GB2 for ALPHA 20:
*** 52 Watt Version ***
Here is the 52W Big Boy (BB) version of ALPHA coming up soon. Waiting for beta test to verify functionality.
Edit April 4, 2018: as-built schematic for Alpha 20 for 1.35amp bias.
Edit April 15, 2018: ALPHA BB GB is proceeding. Cost of 1 pair of 2mm thick FRP, 2oz copper, ENIG finish is $60. Shipping in US is $8, Canada is $17, everywhere else is $24 (10oz weight 240mm x 130mm size is expensive to ship).
Schematic for v2:
Parts placement for v2:
BOM for v2 is here.
Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Thank you AKSA for design and inspiration, JPS64 for layout, and Nelson pass for Aleph CCS!
This is a spin-off from the above thread to keep discussions to the group buy and the build process separate.
Schematic for 20W ALPHA:
Parts placement:
3D render:
Example build with Vishay-Dale/Wima/Silmics:
Another example with non-premium resistors:
Alpha 20 with 1.31amp bias and 2.86vrms into 8ohms gives 0.0069% THD, 0.0059% if using all Vishay-Dale:
BOM and Schematics here (note that there is error on R108, should be 47R not 470R, and for R131 and R132, use Pan ERX 3W 0.47R and 0.22R, respectively for 1.35 amp bias:
http://www.diyaudio.com/forums/soli...rid-aleph-alpha-amplifier-51.html#post5348523
Corrections to previous BOM in BOLD
ALPHA 20 Group Buy PCBs are $28/pair with $5 shipping to USA, $10 to Canda, and $15 everywhere else.
Current list of GB2 for ALPHA 20:
*** 52 Watt Version ***
Here is the 52W Big Boy (BB) version of ALPHA coming up soon. Waiting for beta test to verify functionality.
Edit April 4, 2018: as-built schematic for Alpha 20 for 1.35amp bias.
Edit April 15, 2018: ALPHA BB GB is proceeding. Cost of 1 pair of 2mm thick FRP, 2oz copper, ENIG finish is $60. Shipping in US is $8, Canada is $17, everywhere else is $24 (10oz weight 240mm x 130mm size is expensive to ship).
Schematic for v2:
Parts placement for v2:
BOM for v2 is here.
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Hi X, why not try doing something different and add a new flair to the project. How about using say an LM337 for the CCS because it is simple to fix the current using a single resistor. Get rid of V121. See how much different it sounds if at all. You can then add your name to the list of designers.
V121 is a critical part of the dynamic Aleph CCS by Nelson Pass. Take that out and it is no longer an Aleph. The power efficiency will go down, and the name will not be ALPHA, but ALPHC (doesn't have quite the same ring, does it?)
I say why not change it to LM337 then V121 is unnecessary and it is not an Aleph output stage. It becomes an XRK971 output stage. Oh well I did try to nudge you a little into being daring and making some changes see if it affects the sound at all.
If you do not have an electronic background then I fully understand your reply then forget my I suggestion sorry.
If you do not have an electronic background then I fully understand your reply then forget my I suggestion sorry.
It’s not that I don’t want to try, I have already built another amp with an IRFP240 CCS (controlled by LED) with an IRFP9240 P channel output below. It is the Silicon Harmony. It sounds great but is not as power efficient. In SE Class A mode, the Aleph is a dynamic CCS and will give more of a push-pull character to increase swing. As the very nice PCBs designed by jPs64 are already made, and the amp measures and sounds great, Inhave no need to try an LM337 for the CCS. Besides, isn’t that basically adding 15 transistors of a sort of opamp IC to this simple and elegant 6 actives Class A circuit. Can LM337 handle 4amp current swings?
I did my own amp nods a few projects ago (FH9 Xrk mod being my favorite).
I did my own amp nods a few projects ago (FH9 Xrk mod being my favorite).
I placed the capacitors order from S Korea based on the circuit was drawn by X for this amp and some other projects.
Just realized now when I was checking out this thread the picture X posted (why that capacitor size so large) it is 1000uF not 100uF.
Instead the 47uF I ordered 100uF.
My fault I did not found the BOM when I placed the order so I used the circuit was at hand
.
I also used that to do my layout with the 3 pairs.
6 Weeks until the package arrive if I order it again another 6 weeks. Yeak.
I have at home some Panasonic FC type, not my favorite I think to test the amp it will do the job.
Now the GB will be separate, this way can be better organized.
It is a great idea.
Just realized now when I was checking out this thread the picture X posted (why that capacitor size so large) it is 1000uF not 100uF.
Instead the 47uF I ordered 100uF.
My fault I did not found the BOM when I placed the order so I used the circuit was at hand
. I also used that to do my layout with the 3 pairs.
6 Weeks until the package arrive if I order it again another 6 weeks. Yeak.
I have at home some Panasonic FC type, not my favorite I think to test the amp it will do the job.
Now the GB will be separate, this way can be better organized.
It is a great idea.
Attachments
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The 1000uF 50v feedback shunt cap, can probably be made 220uF with no problem - Panasonic FC is a fine cap. I know what you mean about overseas orders though. Sometimes best to order several values so that it can be used on other projects too rather than on a per amp basis. Good luck with your Alpha build though.
Alpha 20 GB2 Status Update...
danibosn - 2 sets
Yoaudio - 1 set, invoice sent
BRN - 1 set, invoice sent
pieter t - 1 set
danny_66 - 1 set, invoice sent
jvojvo - 1 set
postip - 1 set (no PayPal in Turkey, looking for alternate method)
tonza75 2 set
spind - 1 set
mk15 - 1 set
mrk7 - 1 set
ekidnah09 -1 set
danibosn - 2 sets
Yoaudio - 1 set, invoice sent
BRN - 1 set, invoice sent
pieter t - 1 set
danny_66 - 1 set, invoice sent
jvojvo - 1 set
postip - 1 set (no PayPal in Turkey, looking for alternate method)
tonza75 2 set
spind - 1 set
mk15 - 1 set
mrk7 - 1 set
ekidnah09 -1 set
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That is an odd scale. For ~$16USD*, I think they are a great deal. They aren't cheap, but compared to other caps on that page, they are economical IMO.
*ClarityCap 10 mfd CSA Range with CopperConnect Technology
