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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, 07:17 PM   #2381
cl00sed is online now cl00sed  Ireland
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What about current ratings for the two transformers?
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Old 26th May 2018, 09:57 PM   #2382
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   #2383
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   #2384
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   #2385
maty tinman is offline maty tinman  Spain
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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   #2386
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   #2387
baswamin is offline 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   #2388
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   #2389
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.

Click the image to open in full size.

Inside the new Lyngdorf TDAi 2170 Integrated Stereo:

Click the image to open in full size.

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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Old 28th May 2018, 10:40 AM   #2390
danny_66 is offline danny_66  Belgium
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Quote:
Originally Posted by baswamin View Post
Will the following values of components work fine for Alpha 20?
R131-0.43ohms, R132-0.11ohms, R128-511ohms.
Hi Balaji,

R128-490ohms gives perfect current balance for R131-0.43ohms, R132-0.11ohms
If you don't have 490ohms a little lower value like 470ohm will do fine (better then 510).
Bias is 1.49A

Regards,
Danny
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Last edited by danny_66; 28th May 2018 at 10:49 AM.
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