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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 18th July 2018, 05:56 PM   #2701
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 18th July 2018, 07:13 PM   #2702
Juntuin is online now 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 18th July 2018, 08:57 PM   #2703
xrk971 is online now 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 18th July 2018, 09:28 PM   #2704
Juntuin is online now Juntuin  Finland
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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 18th July 2018, 10:10 PM   #2705
fab is offline fab  Canada
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
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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 18th July 2018, 10:32 PM   #2706
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; 18th July 2018 at 10:53 PM.
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Old 19th July 2018, 01:31 AM   #2707
xrk971 is online now xrk971  United States
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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 19th July 2018, 02:45 AM   #2708
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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Old 19th July 2018, 04:56 PM   #2709
xrk971 is online now xrk971  United States
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This looks like a nice case for an all fan-cooled Alpha. Very IT looking but nice airflow grill holes and built in flow thru fans (which I will drop the speed on).

Amazon.com: Rosewill 4U Server Chassis / Server Case / Rackmount Case, Metal Rack Mount Computer Case with 8 Bays & 4 Fans Pre-Installed (RSV-R4000): Computers & Accessories
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Old 19th July 2018, 09:34 PM   #2710
gaborbela is online now gaborbela  Canada
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Some small progress on the Alpha
The two feet and the faceplate got stained.
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