Aksa Lender P-MOS Hybrid Aleph (ALPHA) Amplifier

Ah, yes, Fab,

But I had a feeling Zman might have more thoughts after a couple of days, because I know he's been listening to it almost continuously........!!

I ask because I know that you really don't fully know an amp unless you've listened to it over many hours, at least 20 hours before you have been through much of your music and figured out where it's good and bad. It's in that long session, over weeks and months, that separates the straw from the chaff.

Hugh
 
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Founder of XSA-Labs
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I have been listening to my Alpha BB for about a month now and have to say, it seems to sound better with age. Maybe there is something to stuff getting burned in and all. It sounds overall just wonderfully smoother. There is a lot of reserve for crescendos and that has always been there. Definitely an amp I am keeping - and I like it open air mounted to showcase how different it is.
 
Zman,

Would you like to give the interested throng here your thoughts about the sound of your ALPHA?

Hugh,

You are right, the amp has been in my system for the past few days, and I've tried to put in some hours of critical listening. I shall try to put my impressions into words. :)

Just to recap on my current setup - Intel NUC as music player, Subbu V3 DAC, Salas DCG3 preamp and Paul Carmody Carrera 2 way speakers.

- Excellent separation between voices (including multiple voices playing simultaneously as in choruses) and instruments. Voices have their own space, and the emotion from voices is rendered nicely.

- Slightly warm + rich tonal balance.

- Sweet but detailed treble, very good mid-range.

- Sound stage is wide and deep, excellent imaging.

- In the lower frequencies, the ALPHA 20 sounds controlled and powerful. It sounds "big".

All in all, a very enjoyable amp - - it sounds "musical" - relaxed and unhurried, a bit like a good tube amp, but with very good resolution, greater headroom and powerful bass.

The PCB is very easy to populate as the parts count is on the low side, and no hard to find components have been used. I did not use any of the trim pots, but went with recommended resistor values, and it is working fine. I hit a snag with a couple of faulty caps, but once that was out of the way, no issues.

I summary, an excellent sounding amp, and of course it was a worthwhile project for me. My thanks again to Hugh, xrk971, and JP for getting this excellent design by Hugh to the diyAudio community. Also thanks to Mr. Pass for the Aleph CCS which is being used in the design. Those who are looking for an excellent sounding (yet relatively easy to build) project, the ALPHA 20 is definitely a solid option!
 
Thank you Zia,

This gives prospective (and continuing) builders an idea of what to expect....... a tube amp with the musicality, depth of image, wide sound field, delicious midrange, and muscular bass.

I would say this is the gold at the end of the rainbow. Hopefully this will become a well known amp in the annals of DIY like so many Pass designs, I really do hope so. And I would thank X, Jean-Paul and Nelson Pass for their pivotal input to the ALPHA for this forum.

Thanks again, Zia,

Hugh
 
If you like the sound with a very low sensitivity (82 dB max) speakers like Carrera... others with 90 dB or more must be amazing!

zman01: very important question here is, which music and DR.

[URL]http://productionadvice.co.uk/wp-content/uploads/2015/03/DR-Infographic-20151.jpg[/URL]

It is not the same if the ALPHA, with 18.9 watts, plays Metallica [COLOR=Red][B]DR3[/B][/COLOR] or Dire Straits [COLOR=Green]DR16[/COLOR] themes.

[URL="http://dr.loudness-war.info/"]Album list - Dynamic Range Database[/URL]
 
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And the speaker distance.

I think, with commercial music DR < 10dB, speakers 89 dB sensitivity and 2m - 3m, a commercial class AB needs about 8 watts if I remember correctly.

listening DR10, 80dB (loud level) + 10dB = 90dB

Pro-Audio and lighting Calculators. Calculator page

* 89dB, 8watts, 3m, random phase: 91.5dB -> in phase: 94.5dB

* 82dB, 18.9watts, 3m, random phase: 88.2dB -> in phase: 91.2dB


ALPHA (18.9watts) + Carrera (82dB) => near field 1.5m in phase: 97.3dB. It is OK with music with high DR.
 
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Maty,

I agree, that dynamic range (DR) is a very important aspect of "realism"... A few words on that with respect to my personal listening situation.

Most of the times I listen at moderate levels - usually around 78-80 dB in a medium sized room. When I am around 80-82 dB (average) at my listening position, that's plenty for me. My taste covers a wide spectrum, and lot of the music I listen too (pop, electronic, rock, metal) is not that well recorded, neither do these recordings have very high dynamic range. I do like Dire Straits a lot and am aware some of their recordings (produced by Bob Ludwig) have excellent DR. I've played selected tracks from Brothers in Arms and On Every Street, and the rendition was very nice. I would also assume that with higher efficiency speakers the listening experience can be even better - more jump factor, greater dynamics and impact...but as it is, I am a happy camper for now. I do have parts for a 90+ dB speaker, but need to build that. Another alternative is that I build a ALPHA BB - that is capable of rocking out more. :) We did try the ALPHA 20 with a 90 dB sensitive wide-band speaker (Mark Audio Alpair 10P bookshelf) and those could be driven to loud levels effortlessly.

One thing I am really liking about the ALPHA 20 is that the nuances of voice and instruments can be easily discerned - subtle inflection of vocals, percussion work, plucking of guitar strings etc. In my experience these things matter, and help transform good listening experiences to great ones. :)
 
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My Alpha BB continues to work well. After a month the noise with volume turned down on preamp is 100uV rms and DC offset is 0mV. It is an amazing sounding amp that is easy to live with.

Noise at output:
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DC offset at output:
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18.9 watts RMS.

But when you want to know the potential you have to take into account the peaks of music/sound. That is why, in order to play orchestral music, class AB amplifiers of many watts are usually sought. And already, they buy audiophile amplifiers of 200watts or more -> H3 predominant

The sound is more detailed but frightens the tubes lovers and those who usually listen to live orchestras or live music like jazz, acoustic... without a lot of electronics, computer instruments and autotune.

The merit is to get that detailed sound without the odd harmonics.

With great soundstage and... too.


The other possibility, with speakers with low sensitivity, is the AKSA Lender preamp, modified to less output voltage and the H2 level you like/want (first with trimpots and after with only resistors). And a clean, without harmonics, but not sterile poweramp.


AKSA's Lender Preamp with 40Vpp Output

Or maybe the AKSA Lender with 40Vpp + ALPHA. With digital volume or logarithmic 64 or more step relays from the new JPS64 designs.

You need to make simulations, adding a margin safety. 80dB and DR17 is mine.
 
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xrk971, you show off! :D I am getting tempted... have to remove these thoughts of building another amp.... aghhh

Enjoy your ALPHA BB! :)
A big conern for me is that I can't listen to the amp in silence.
So that said I cannot see the point of background noise to be a good thing to add to the push pull amplifier. In a true a class the difference to Ab let's say at 1W in A to hear the difference is a academic topic. As aksa said music is symmetric witch basically means best for rock 4/4. This is a academic topic also. So my conclusion as I have to set 2 or 4 for stereo artic extreme 3 300W it's not enough to exclude fan noise. Maybe others play music so loud that the small nuances are under thrown to the fan noise on their 24bit recordings.
That's my view. If I need PA amp at home with fan noise to cancel on one thing, and same thing,. do they cancel each other out completely?
 
You can not hear < 19 dB I think => Big fans with low revolutions and amplifier or PC computer > 1 m from your ear is the key. Off course, amplifiers inside a case!

PC computer with big fans < 1m => add inside soundproofing material. PSU with silent 12mm fans. And with low ripple at 5 Vdc (USB output -> DAC).

If you use very powerful graphics cards and squeeze them, better not listen to quality music until they stop working so hard.
 
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You can not hear < 19 dB I think => Big fans with low revolutions and amplifier or PC computer > 1 m from your ear is the key. Off course, amplifiers inside a case!

PC computer with big fans < 1m => add inside soundproofing material. PSU with silent 12mm fans. And with low ripple at 5 Vdc (USB output -> DAC).

If you use very powerful graphics cards and squeeze them, better not listen to quality music until they stop working so hard.
Build yourself and then comment, do that then reply.
 
If your BB52 requieres big fans but high revolutions you have a problem. Lowering the power/heat you can reduce the revolutions -> less noise.

Big class A amplifiers are always problematics.
That's correct, with multiple irfxxxx in parallel we can decrease current/ power trough devices.
It's one way but I think it's not important on this thread. Nor a 0.22R to the irfp9240 as it works flawlessly in a enclosure diy audio as it was designed for and tested.
 
Irribeo,

Calculation of power from the ALPHA, and all of my amps, is based on Peak Sine rail to rail SQUARED, then divided by 64 - for 8R. For 4R, Vppexp2/32.

This is peak power and it is based on peak to peak sinewave.

X, you are approaching the limits of audio porn. Stop it. Please......

HD
Thank you aksa. For your contribution on this thread.
A good engineer as you said cost will be low.
Needed equipment to good engineering is though not cheap.
 
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