Aksa Lender P-MOS Hybrid Aleph (ALPHA) Amplifier

[BRN]

That’s the cap Mx I ordered, so should work well. If you did not make any changes from your earlier post it was the lower setting.

The BB looks really cool, I just don’t have space for it otherwise it would be at the top of my list.

Thanks for the info,
Brad

 

[xrk971]

The BB looks really cool, I just don’t have space for it otherwise it would be at the top of my list.

This doesn't take any space... 😀

Just connect it to a small aquarium pump.

 

[thimios]

I have a question, is this Alpha 20w suitable for 8ohm speakers only?
My first test was using a 4ohm speaker.

 

[AKSA]

Thimios,

First, congratulations on completely your ALPHA.

It is designed for 8R with dips to 6R. However, it will run with a 4R load until it current limits, which would be at around 3A. This would be a peak of 12Vp, which is around 18W. If you wish to take it to more output, essentially you need only increase the quiescent current, to about 2A. To do this, change only the R131 resistor in the source of the nmos to 0.3R. You can optimise things more than this one resistor, Danny from Belgium has done a lot of work on this and in this thread you will find his table which lays out the changes for optimised power.

BUT, I would suggest you leave it as it is and simply move to efficient 8R speakers!

Ciao,

Hugh

 

[zman01]

thimios,

With reference to Hugh's post above please find link to Danny's table:

https://www.diyaudio.com/forums/sol...id-aleph-alpha-amplifier-166.html#post5400230

 

[thimios]

Thimios,

First, congratulations on completely your ALPHA.

It is designed for 8R with dips to 6R. However, it will run with a 4R load until it current limits, which would be at around 3A. This would be a peak of 12Vp, which is around 18W. If you wish to take it to more output, essentially you need only increase the quiescent current, to about 2A. To do this, change only the R131 resistor in the source of the nmos to 0.3R. You can optimise things more than this one resistor, Danny from Belgium has done a lot of work on this and in this thread you will find his table which lays out the changes for optimised power.

BUT, I would suggest you leave it as it is and simply move to efficient 8R speakers!

Ciao,

Hugh

Thanks Hugh!
I ask to know if mine run hot due to low impedance load.

 

[thimios]

thimios,

With reference to Hugh's post above please find link to Danny's table:

https://www.diyaudio.com/forums/sol...id-aleph-alpha-amplifier-166.html#post5400230

Thanks zman01 for the link.

 

[BRN]

Putting my BOM together for the Aplha 20W and want to be able to change amps boards easly and see that the posted BOM has male molex connectors, but no female connector. Is this one from Mouser (571-3-641237-2) a good option?

 

[Juntuin]

Thimios, nice to see newborn Alpha 🙂

 

[xrk971]

Putting my BOM together for the Aplha 20W and want to be able to change amps boards easly and see that the posted BOM has male molex connectors, but no female connector. Is this one from Mouser (571-3-641237-2) a good option?

I think it is a fit but cannot say for sure as I use JST jacks/plugs. For nitty-gritty build and parts questions, I think the GB thread might be a better place to ask.

https://www.diyaudio.com/forums/gro...-aleph-alpha-class-amp-gb-23.html#post5583813

 

[thimios]

Second chanel singing.

 

[thimios]

First time playing in stereo. 😎

 

[AKSA]

How's it sound, Thimios?

Does it get hot? What is the quiescent current?

Hugh

 

[thimios]

How's it sound, Thimios?

Does it get hot? What is the quiescent current?

Hugh

Because one power supply is fixed +/-18v(from an existing SX class A) i manage to run both chanels using same voltage(one using two variables bench power supply and the other using the existing Bonsai SX class A power supply.
Power supply +/-18v
offset after warming period=15mV
Heatshink temp.=54 C
Temprature direct on fet body=67 C
Speakers are 4ohm(no circuit modifications), keeping volume at the midle(laptop player).
Listening period about an hour,not enough .....
How's it sound?
Cheap speakers playing wonderful!
Yes i like this a lot.
I can <<place>>the organs in the orhestra!
That's for now.
Thanks Hugh for this wonderful simple amplifier!😎

 

[xrk971]

Congrats on stereo Alpha 20, Thimios! Connect some sensitive full range speakers (90dB+) and enjoy.

 

[thimios]

Congrats on stereo Alpha 20, Thimios! Connect some sensitive full range speakers (90dB+) and enjoy.

Thanks xrk971 but i haven't any😡

 

[xrk971]

Get some Faital Pro 3FE25-16's, make a 0.53x Karlsonator (out of foam core or wood) and you have a 93dB speaker with rich, full sound. $80 for 4 drivers and $10 for foam core and glue.

Mini Karlsonator (0.53X) with Dual TC9FD's

Plans here:
http://www.diyaudio.com/forums/atta...fds-0-53x-karlsonator-score-fold-plans-mm-pdf

Or use four TC9FD's for 92dB at 2.83v (4ohms) in same speaker box. These are only $12/ea or$48/set. It is possible that with basic tools like a razor, ruler, hot glue gun, and foamcore, and drivers, anyone can have a nice high sensitivity (90dB+) full range speaker for under $100.

Here is what they look like during construction, these were made by bcmbob:

Listen to the sound clips at the bottom of Post 1 if you wonder what it sounds like. This speaker has at least 100 successful builds around the world.

I had a pair in foamcore, but was lucky enough to have a set made for my by member jhofland as a gift (photo above being powered by Hugh's Omega 35 Class A amp). Lucky me. 😀

Thank you, jhofland!

 

[AKSA]

WOW, what a simple system........

HD

 

[xrk971]

Folks, don't forget to check out the GB/Build thread for this amp. Lots of good info there as well.

Aksa Lender P-mos Hybrid Aleph (ALPHA) Class A Amp GB

 

[gaborbela]

To X or Huge
The C112 0.01uF can be only an FKP type? I don't have at home, I do have MKP type (polypropylene). To place an order for 2PC 50Cent value caps that is not me in my situation. Unfortunately, I miss that when I made my order and today at the stuffing the PC boards just realized it.
Please let me know.
Thank you