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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
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Old Yesterday, 05:31 PM   #2701
gaborbela is offline gaborbela  Canada
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With the 22V transformer, you get 26.4V plus U use CRCRCRC power supply. With the 3pc R you burn up some power also. I hope you not using any high-value resistors there to burn up more power. Your 25.6V is absolutely normal with your setup.
When you buy a transformer to regular Class A bias calculation(not talking about Alep X where the total bias is over 7A per channel) 22ACV x 1.2 under load =26.4V DC.
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Old Yesterday, 05:56 PM   #2702
tonza75 is offline tonza75  Europe
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I think you know better and waiting for someone to answer.
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Old Yesterday, 07:13 PM   #2703
Juntuin is offline Juntuin  Finland
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B.B. one channel: 39,7vdc under load. 2x30vac sec 545va trafo. Can't remember or measure Alpha20 right now..
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Old Yesterday, 08:57 PM   #2704
xrk971 is offline xrk971  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Quote:
Originally Posted by gaborbela View Post
With the 22V transformer, you get 26.4V plus U use CRCRCRC power supply. With the 3pc R you burn up some power also. I hope you not using any high-value resistors there to burn up more power. Your 25.6V is absolutely normal with your setup.
When you buy a transformer to regular Class A bias calculation(not talking about Alep X where the total bias is over 7A per channel) 22ACV x 1.2 under load =26.4V DC.
I am using 0.15R - ok so normal. My problem is that I have been using 1.4x and subtracting 3-4v for load. But 1.2x multiplier seems way to go for Class A. My CRCRCRC burns off 1.2v.
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Old Yesterday, 09:28 PM   #2705
Juntuin is offline Juntuin  Finland
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Quote:
Originally Posted by Juntuin View Post
B.B. one channel: 39,7vdc under load. 2x30vac sec 545va trafo. Can't remember or measure Alpha20 right now..
Oh, forgot that CCRCCRC where 0.2ohm per resistor.
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Old Yesterday, 10:10 PM   #2706
fab is offline fab  Canada
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Quote:
Originally Posted by xrk971 View Post
?...
I recently bought a pair of 22VAC 300VA Anteks, hoping to get a solid 27vdc under load of 1.6amps. After the CRCRCRC, I am getting 25.6v. This is for a high output variant of the Alpha 20 that I am testing - just seeing if pushing higher voltage and increased cooling via CPU coolers and fans can work to boost power output.
Hi X
Antek supplier specifies output voltage under specific load current (not much data though) with 120vac input. In my area line voltage from provider can vary from 115 to 122vac (I have a real time indicator) in normal situation (not too cold/hot weather). Mostly depends on time of the day with demands from all houses/buildings.
Also, rectifier diodes have different voltage drop depending on their temperature. Check the specific data sheet of your diodes.
And then you add the voltage drop of the resistors in series in your PSU.
Fab
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Old Yesterday, 10:32 PM   #2707
Vunce is offline Vunce  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
With my 600va, 32v transformers, my BB’s are running at 37.5vdc with a CRCLC. If I use a capMx instead of the CRCLC the voltage increases to 38vdc.
Since it’s summertime, my line voltage varies widely during a 24 hr period. Anywhere from 112vac to 125vac.
I think my ALPHA20 is running 23vdc, I’d have to check (don’t remember).

I did notice that the DC offset increased from 10mv @36vdc to 25mv @37.5vdc?

Last edited by Vunce; Yesterday at 10:53 PM.
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Old Today, 01:31 AM   #2708
xrk971 is offline xrk971  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Hi Vunce,
You must have some big power with 37.5v rails. I am guessing upwards of 70w? You have these 99dB Klipsch speakers so would never know what 70w feels like on the B.B.
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Old Today, 02:45 AM   #2709
Vunce is offline Vunce  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
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Originally Posted by xrk971 View Post
You have these 99dB Klipsch speakers so would never know what 70w feels like on the B.B.
Exactly X
My Forte’s play incredibly loud with the ALPHA20. The appeal about the BB is that I get to use a powerful Class A amp with much less efficient speakers that I have.
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