It takes a little more time though, devil is in the details and I hate details
Edit; at least painting went quite well..when done second time all over..
Would like to see fresh builds too!
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Any new Alphas alive? There were quite a many PCB's sold after all
Juntuin,
I got my one up up and running:
http://www.diyaudio.com/forums/soli...id-aleph-alpha-amplifier-219.html#post5429059
No pics yet, as I'm getting a few details on the chassis sorted out.
I have framework almost ready, couple of things to do. It is now black, it's big and it's mean.
Look forward to your "new look" ALPHA 20!
Hello X and builders (PASS one concerned too),
what do you think about universal power supply?
- CLC (XLR input connector as option otherwise hole or faston)
- dual bridge (8x TO247/TO220 and snubber)
- CapX (credits goes to @Prasi and @JUMA, his logo and her name on board)
- CRCRC (châssis grounding included)
25EUR pro panel (by 50 pieces order): 442x110x2mm, 70µm CU, ENIG, silkscreen and vias cemetery.
JP
what do you think about universal power supply?
- CLC (XLR input connector as option otherwise hole or faston)
- dual bridge (8x TO247/TO220 and snubber)
- CapX (credits goes to @Prasi and @JUMA, his logo and her name on board)
- CRCRC (châssis grounding included)
25EUR pro panel (by 50 pieces order): 442x110x2mm, 70µm CU, ENIG, silkscreen and vias cemetery.
JP
Attachments
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JP,
I really like that idea, as I’d like to try using a CLC for my BB build. Your proposed design has many features to it that would be helpful.
It’s probanly more a matter of the max power dissipation. If going 32v on Alpha 20, you need to swap to big IXYS TO-264 MOSFETs as it is now putting out 50w ea (assuming 1.5amp bias). I think you have two attached to one CPU cooler and they can do 125w so should be ok the with a fan. But since IRP240/9240 are so cheap, you could try it (with dummy resistor load) and see what happens. You will need to adjust the LTP bias resistors to limit LTP total current to 2mA. Probably copying the settings for Alpha BB is your best bet for runnning at 32v rails. 50w is over the SOA of the IRCP240/9240.
Thanks X.
I have a pair of Hypex SMPS’s just sitting in the draw waiting for a home. I would use them for the BB, but I don’t think they can supply enough current
(3.4A continuous)
If I use them with a CapMx, I can get the voltage dropped to about 32Vdc, I would not rework my current ALPHA20 for this power supply, it would be a complete new build with the heavier duty output devices.
I have a pair of Hypex SMPS’s just sitting in the draw waiting for a home. I would use them for the BB, but I don’t think they can supply enough current
(3.4A continuous)
If I use them with a CapMx, I can get the voltage dropped to about 32Vdc, I would not rework my current ALPHA20 for this power supply, it would be a complete new build with the heavier duty output devices.
You can always drop voltage with bigger R’s on CRC. Just make sure they are rated for the power. Bigger R values will really reduce ripple but get hot. It’s ok for Class A as long as you are strong the requisite steady state bias current you need. There is no dynamic current requirements on SE Class A, unlike Class AB. A Cap Mx is also good for 4v drop.
Hi Vunce,
I've done a bit of work with a friend on smps for audio amplifiers. We found that after we spent money on additional caps and inductors to clean up the sound, the total cost was higher than a good linear with a CRCRC.
Paul, a good friend of mine, did some spice work on power supply ripple. He found that a cap multiplier reduced the ripple to very low levels with modest caps, but the ripple was more like a sawtooth than a sinewave. This begs the question about whether the higher orders of the 100/120Hz intrude into the audio band; he found that a CRCRC was not as efficient, and certainly more expensive, but the small ripple was a good sinewave, very few high orders.
After all the enthusiasm for the ALPHA I'm building one too. I have used four 15mF caps with three pairs of 0.15R resistors, a CRCRCRC, for EACH rail - all on one pcb. I calculate that ripple will be around 12-15mV but pure sinewave, and I'm hoping that the high PS rejection ratio should leave it silent. I'm using 480W mosfets and will use around 26V on the rails.
I'll let you know and send the photos!!
Cheers,
Hugh
I've done a bit of work with a friend on smps for audio amplifiers. We found that after we spent money on additional caps and inductors to clean up the sound, the total cost was higher than a good linear with a CRCRC.
Paul, a good friend of mine, did some spice work on power supply ripple. He found that a cap multiplier reduced the ripple to very low levels with modest caps, but the ripple was more like a sawtooth than a sinewave. This begs the question about whether the higher orders of the 100/120Hz intrude into the audio band; he found that a CRCRC was not as efficient, and certainly more expensive, but the small ripple was a good sinewave, very few high orders.
After all the enthusiasm for the ALPHA I'm building one too. I have used four 15mF caps with three pairs of 0.15R resistors, a CRCRCRC, for EACH rail - all on one pcb. I calculate that ripple will be around 12-15mV but pure sinewave, and I'm hoping that the high PS rejection ratio should leave it silent. I'm using 480W mosfets and will use around 26V on the rails.
I'll let you know and send the photos!!
Cheers,
Hugh
Hugh,
This is fantastic news that you are joining in the ALPHA20 build
I’m looking forward to hearing your own impressions of the amp.
At the moment, my ALPHA20 is dialed in very well. It’s more out of curiosity to implement the SMPS’s I have to compare against the linear power supply version.
Cheers,
Vunce
Check this LaScala Power Amp, its a class A amp and also using heatpipes. Means to say, this is becoming popular for Class A amps instead of using bulky heatsinks.
Mono and Stereo High-End Audio Magazine: CANEVER AUDIO LASCALA POWERAMP
Mono and Stereo High-End Audio Magazine: CANEVER AUDIO LASCALA POWERAMP
For me they look like the noctua . Noisy , noctua d15
noctua-nh-l9x65-cpu-cooler-65mm look more like those
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Cheaper and better and more quiet than the Noctua in LaScala amplifier is Zalman CNPS8900 or whatever they call that size copper spiral looking top-down sinks these days, expect around 10 degrees Celsius higher temperature than cheaper xrk's Deepcool at similar noiselevel (Noctua pictured with LaScala around 25 degrees Celsius higher temperature (for 36V BBversion) and 10 dB higher noiselevel (compared to xrk budgetcooler). (might get you from futuristic proto to finished amp, easier)
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