Aksa Lender P-MOS Hybrid Aleph (ALPHA) Amplifier

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J

Juntuin

Member
Joined 2015
xrk971 said:
Add CLC in between fan and your supply. About 470uF and 1mH 470uF (51ohm parallel withL) is what I use. Also 0.1uF 250v film cap bypass on those electrolytics. If you have the Aksa Lender Preamp it comes with a small CLC that both Vunce and myself use and it prvents noise from coming back. You can also just wire it P2P. You can also use 7812 in TO220 to drop your 35v to 12v. Or if higher voltage than LM317HV.
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Hmm. I like those regulators. Do they need any additional filtering? They probably have some already inside, seems to have 80db ripple reduction.

AKSA said:
Juntuin,

Terrific work! I like the fans bottom, amp above, power supply caps above that. Very elegant, almost like a guitar amp case.

With 37.5V supply you should get about 55W out of the BB. It will clip first on the negative rail, around -30V. This is 56W, impressive for a Class A. I'm amazed that the fans make no noise even at full tilt!

HD
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Thanks Hugh, I rolled parts around many times and this is what i came up.. Aye, more POWER :D

zman01 said:
Juntuin,

Good to see one channel up - nicely done!
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Thanks Z! Let's see can we get any sound out of it :D

gaborbela said:
Yes, it is a nice amplifier, I wish I could have the possibility to build something like that. Unfortunately, I can not do that while I live in an apartment on the kitchen table neither on the balcony. If you would accept an advice please Try to use as short and thick wires as possible especially between you PC boards and the capacitor banks. If is too far away because of the construction maybe use an extra pair high-quality caps just before your PC boards, like a pair M Lithic. Mr. Pass always advised us at DIY Aleph amps thick and short wired as possible. If you can do that a par extra caps like 10 000uF close to you PC boards.
1pair Car Battery Booster Line Jumping Cables Power Fire Wire w/Heavy Duty Clip | eBay

25 FT True 8 Gauge Awg Speaker Wire Pro Cable Blue White Car & Home Audio Spool | eBay
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Hi Gaborbela!
I build also in our bedroom floor, painting, sanding drilling happens outside in summertime :) at wintertime you just don't paint.. Girlfriend made weldings at her work, everything else is made sitting on the bedroom floor. So you can build there also, but I wont lie to you, it really sucks.
Good advice with wires! I was thinking just yesterday how to keep them as short as possible. They came almost exactly 20cm long, hope that not too long then..
 
xrk971

xrk971

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Joined 2012
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Hmm. I like those regulators. Do they need any additional filtering? They probably have some already inside, seems to have 80db ripple reduction.
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You still need the CLC between the PSU and the regulator to isolate the supply from fan’s own brushless motor pulses. All voltage regulators like 78xx or LM31x etc need low ESR bypass cap as close to pins of regulator as possible. They recommend 0.1uF X7R ceramic on input and 1uF X7R/tantalum on output pin plus a 10uF electrolytic on output.

For L on CLC just a cheap ferrite core 1mH that costs <$1 is fine. 10mm dia radial types.
 
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J

Juntuin

Member
Joined 2015
AKSA said:
She'll get you yet, Juntuin!!

HD
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:D

xrk971 said:
You still need the CLC between the PSU and the regulator to isolate the supply from fan’s own brushless motor pulses. All voltage regulators like 78xx or LM31x etc need low ESR bypass cap as close to pins of regulator as possible. They recommend 0.1uF X7R ceramic on input and 1uF X7R/tantalum on output pin plus a 10uF electrolytic on output.

For L on CLC just a cheap ferrite core 1mH that costs <$1 is fine. 10mm dia radial types.
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Ok, good to know, thanks.
 
xrk971

xrk971

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Joined 2012
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Alu L-clamp for bigger ixys gets quite hot, maybe not enough pressure against heatsink.
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When heat transfer is good to heatsink/CPU cooler, the aluminum clamp is pretty cool - mine are like 32C to 38C - varies with pressure I think. This is measured using a Kapton tape patch on the top of the clamp above the MOSFET and an IR thermometer.
 
J

Juntuin

Member
Joined 2015
xrk971 said:
When heat transfer is good to heatsink/CPU cooler, the aluminum clamp is pretty cool - mine are like 32C to 38C - varies with pressure I think. This is measured using a Kapton tape patch on the top of the clamp above the MOSFET and an IR thermometer.
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I suspected that also, because other fet was quite cool. But I don't worry that now, going for quick test anyway :D I have to take it apart anyways for more building.
 
T

tonza75

Member
Joined 2010
xrk971 said:
When heat transfer is good to heatsink/CPU cooler, the aluminum clamp is pretty cool - mine are like 32C to 38C - varies with pressure I think. This is measured using a Kapton tape patch on the top of the clamp above the MOSFET and an IR thermometer.
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And your voltage & bias with those temps. May second computer has a delta about 30°C with a 140W load and a corsair H150. After >30min.

Have you tried different measuring temperature tools?
 
Vunce

Vunce

Member
Joined 2014
Paid Member
xrk971 said:
When heat transfer is good to heatsink/CPU cooler, the aluminum clamp is pretty cool - mine are like 32C to 38C - varies with pressure I think. This is measured using a Kapton tape patch on the top of the clamp above the MOSFET and an IR thermometer.
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X,
What’s the voltage your BB is running?
I’m getting 46C-50C on my MOSFET L-clamp running 37.5vdc.
 
J

Juntuin

Member
Joined 2015
Ok, that was busy day :D I'm cursing my active setup now (again), quite hard to tell characteristics of amp. Of course I've had very different amp last time and dsp's settings and gains were all wrong. So I did just a quick 5min test to confirm sound and noises. After that I took some alu sheet and cut rear panel, installed dc-prot/delay and confirmed that it works also. Second one have to wait for over a month, since we are starting our summer vacation after next week, so no welding :D but I can cut some alu plates already etc, second one is much faster to fabricate. And of course this first one needs side plates, roof, power source for fans and bypass caps.
 
xrk971

xrk971

Founder of XSA-Labs
Joined 2012
etsy.com/shop/XRKAudio
Paid Member
I'm cursing my active setup now (again), quite hard to tell characteristics of amp.
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I used to use active DSP speakers too for a long time, but switched to a good reference quality passive crossover speaker exactly for this reason: to be able to judge the effect of different amplifiers. My speakers have a pretty benign impedance curve so as to not affect the amp/crossover interaction.
 
J

Juntuin

Member
Joined 2015
wtl said:
Nice work Juntuin i have not done any more on my BB too much to do around the house.
Steve.
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Thanks! Please post your progress when you have time and inspiration to go forward :)

xrk971 said:
I used to use active DSP speakers too for a long time, but switched to a good reference quality passive crossover speaker exactly for this reason: to be able to judge the effect of different amplifiers. My speakers have a pretty benign impedance curve so as to not affect the amp/crossover interaction.
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I'm solving this problem also, JBL's go to my sisters warehouse and gotta get some passive speakers as replacement. No time to build so commercial it is.

AKSA said:
Juntuin,

Congratulations on your latest, this is wonderful work. With 55W in Class A, it should sound seismic on your efficient speakers. Should raise the roof, actually.

HD
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Thanks Hugh, it is really lots of class-A power! Hard to find anything commercial to match atleast any reasonable price point.
 
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