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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 26th May 2018, 06:51 PM   #2381
BRN is offline BRN  United States
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Quote:
Originally Posted by AKSA View Post
Brad,

No change to existing supply. Just one trafo with 20Vac secondaries, one winding to positive rail one channel and the other winding to the positive rail other channel. The second trafo would have 22Vac secondaries, with one winding to negative rail of channel ONE and the other winding to negative rail of channel TWO.

No changes. No additional parts or cost. Just two different trafos. You go up from 19W to 25W, and increase of 31% for peanuts.

Hugh
Hugh,

Is this what you means?

Brad
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Old 26th May 2018, 07:17 PM   #2382
cl00sed is offline cl00sed  Ireland
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Quote:
Originally Posted by BRN View Post
Hugh,



Is this what you means?



Brad


What about current ratings for the two transformers?
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Old 26th May 2018, 09:57 PM   #2383
Vunce is offline Vunce  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Thanks folks
Iíve got an extended weekend so Iím hoping to power one channel up.

Danny,
I increased R111 on the Alpha 20 to 2k2ohms. I did notice a slight decrease in the gain but I will not go any further. As you know, changing one component affects others down the line....

Tonza,
The red color makes them sound better
Iím using these mosfets:

IXTK90P20P IXYS | Mouser

IXTK88N30P IXYS | Mouser

Regards,
Vunce
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Old 26th May 2018, 10:51 PM   #2384
AKSA is offline AKSA  Australia
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Toroids are the same VA rating.
High voltage AC output reduces current proportionally but not relevant here with good filter caps.

The wiring picture in Brad's post #2381 is absolutely correct.

HD
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Old 27th May 2018, 05:07 PM   #2385
Juntuin is offline Juntuin  Finland
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Is 4U Dissipante enough for higher bias Alpha 20 (1,93A)??

Today we placed Alpha against Lyngdorf integrated, speakers were JBL 4341 monitors.

Alpha succeeded much better on every area, except Lyngdorf kept better control on bass. Surprisingly Alpha went lower though. Higher register improved most with Alpha, you could hear it in a second.
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Old 27th May 2018, 05:47 PM   #2386
maty tinman is offline maty tinman  Spain
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[PDF] http://www.jblpro.com/pub/obsolete/4340_4341.pdf

Sensitivity: 83.5 dB/1watt at 3m

Pro-Audio and lighting Calculators. Calculator page

=> about 92.5 dB/1watt at 1m

Only (without graph) nominal impedance: 8 Ohms
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Old 27th May 2018, 06:42 PM   #2387
xrk971 is offline xrk971  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Quote:
Originally Posted by Juntuin View Post
Is 4U Dissipante enough for higher bias Alpha 20 (1,93A)??

Today we placed Alpha against Lyngdorf integrated, speakers were JBL 4341 monitors.

Alpha succeeded much better on every area, except Lyngdorf kept better control on bass. Surprisingly Alpha went lower though. Higher register improved most with Alpha, you could hear it in a second.
1.93amp x 24x2v is ~90w per channel which I think a 5U Dissipante would be better. At 1.35amps it is 45C.
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Old 27th May 2018, 07:34 PM   #2388
baswamin is online now baswamin  India
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Guys,

Will the following values of components work fine for Alpha 20?

R131-0.43ohms, R132-0.11ohms, R128-511ohms.

I got them from danny's calculations on post 1652 and 2158 but is mix and match of values mentioned. Plan is to bias at 1.46A.

Thanks
Balaji
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Old 28th May 2018, 05:50 AM   #2389
tonza75 is offline tonza75  Europe
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What is your usual temperature įC where your listening.
Calculate heatsink requirements.

With Irfp240 9240 in circuit take account the ~10V dc when they conduct ~ > 200ma in circuit.

Ask yourself how many watts you need vs temp.

There are many options but it's for you to decide.

I been in India a 2 times.

Have Fun.
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Old 28th May 2018, 07:52 AM   #2390
maty tinman is offline maty tinman  Spain
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Quote:
Originally Posted by Juntuin View Post
..Alpha succeeded much better on every area, except Lyngdorf kept better control on bass. Surprisingly Alpha went lower though. Higher register improved most with Alpha, you could hear it in a second.
If I am not wrong, they are class D amps -> ridiculous output impedance -> more and better controled bass.

Btw, ten years ago, Lyngdorf SDA-2175, I see a RF/EMI filter inlet with class-D.

[IMG] http://www.hifishock.org/galleries/e...1-lyngdorf.jpg

Inside the new Lyngdorf TDAi 2170 Integrated Stereo:

[IMG] https://www.audiovisualonline.co.uk/..._l_9-large.jpg


Class A amps need a very good PSU -> you need to spend money in this section.

Last edited by maty tinman; 28th May 2018 at 07:55 AM.
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