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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 Yesterday, 12:15 AM   #2581
pinnocchio is offline pinnocchio  Canada
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I have a set with parts I bought from PMI back in the days but never even unwrapped them. Maybe I'll try them.
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Old Yesterday, 01:08 AM   #2582
xrk971 is offline xrk971  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Quote:
Originally Posted by Vunce View Post
....and another psu to try with the Alpha BB.
I decided to try another capMx, this one is: Simplified MrEvil / PMI Capacitance Multiplier by Jason Kuetemann. I had very good results using the Allo CM board with my Big MoFo amplifier so, when I found out the Allo was a positive rail only copy of this circuit I decided to try the full version for my BB.
So far the results are much better than the first capMx I tried. I have it adjusted to drop only 1.5vdc and the heat generated from the MosFets is very manageable. The Wakefield 272 heatsinks are reading 55°C. Im using off-board bridge rectifiers instead of T0-220 on-board rectifiers which is a nice option this board incorporated.
Nice work, Vunce. I was meaning to try this too and glad you did. Does it also provide a slow ramp up that prevents speaker thump?
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Old Yesterday, 01:39 AM   #2583
Vunce is offline Vunce  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
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Originally Posted by xrk971 View Post
Does it also provide a slow ramp up that prevents speaker thump?
Hi X,
No, this capMx doesn’t stop the turn-on thump/cone excursion.
I also put the Fo-Felix EMI Filter for AC mains 120/230v; By Folsom, into the mix. It’s installed between mains input and trafo primaries. I’ve documented in the past the noises I was getting when different combinations of led recessed lights were on throughout my house. I am pleased to say that this filter eliminated almost all the “extra” noises/buzzing I was hearing close to the speaker.

Last edited by Vunce; Yesterday at 01:52 AM.
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Old Yesterday, 05:23 AM   #2584
Juntuin is offline Juntuin  Finland
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I have to double check this, B.B.'s bias current is 3A?
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Old Yesterday, 05:25 AM   #2585
AKSA is offline AKSA  Australia
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Yes, Juntuin, 3A is quiescent.

HD
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Old Yesterday, 05:27 AM   #2586
Juntuin is offline Juntuin  Finland
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Quote:
Originally Posted by AKSA View Post
Yes, Juntuin, 3A is quiescent.

HD
Thanks for confirmation Aksa just looking for suitable chokes for CLC, 5A rated should be enough then per channel.
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Old Yesterday, 06:17 AM   #2587
AKSA is offline AKSA  Australia
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Yes, run it close to rated current to maximise the inductance......
You will need two for each channel, of course, it's expensive and heavy.
I would use around 20mH with DCR no more than 0.66R to minimise losses.

I have an ALPHA running 1.85A and simple CRCRCRC, with two resistors of 0.15 between all electrodes of the caps. That seems to be very quiet and drops 1.66V over the chain. Each RC has an attenuator of around 5, so three RC gives me 125 ripple attenuation, finishing with around 15mV at the output devices. This is sufficient because the first and second stages are heavily filtered.

Cheers,

HD
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Old Yesterday, 06:18 AM   #2588
xrk971 is offline xrk971  United States
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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Quote:
Originally Posted by Vunce View Post
Hi X,
No, this capMx doesn’t stop the turn-on thump/cone excursion.
I also put the Fo-Felix EMI Filter for AC mains 120/230v; By Folsom, into the mix. It’s installed between mains input and trafo primaries. I’ve documented in the past the noises I was getting when different combinations of led recessed lights were on throughout my house. I am pleased to say that this filter eliminated almost all the “extra” noises/buzzing I was hearing close to the speaker.
That's great that the mr Evil cap mx works to smooth ripples and do the cap multiplying thing, but that's too bad it doesn't have the slow ramp effect. I wonder if changing an RC time constant on the circuit would do this?

Good to hear that the Fo-Felix helps the buzzing noise pickup from the LED lamps and EMI in general. I think it blocks DC too? That might be one reason why the Antek's get saturated.
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Old Yesterday, 06:22 AM   #2589
Juntuin is offline Juntuin  Finland
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Quote:
Originally Posted by AKSA View Post
Yes, run it close to rated current to maximise the inductance......
You will need two for each channel, of course, it's expensive and heavy.
I would use around 20mH with DCR no more than 0.66R to minimise losses.

I have an ALPHA running 1.85A and simple CRCRCRC, with two resistors of 0.15 between all electrodes of the caps. That seems to be very quiet and drops 1.66V over the chain. Each RC has an attenuator of around 5, so three RC gives me 125 ripple attenuation, finishing with around 15mV at the output devices. This is sufficient because the first and second stages are heavily filtered.

Cheers,

HD
I know, they go about 15-20€ per piece, so almost 80€. I havent bought anything yet, just planning. Have to measure that can I even fit those chokes inside. More R is not a problem, since I have 30v trafo secondaries.
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Old Yesterday, 09:14 AM   #2590
suresh is offline suresh  India
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Quote:
Originally Posted by AKSA View Post
Some beautiful examples of the ALPHA here!
I have almost completed my ALPHA and will shortly post my photos.

HD
Eagerly waiting to see the photo of your build .
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