The Aleph-X

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#2,141
Bricolo said:



you're right!
+-12V rails means 72W max on 8R, and 144W max on 4R (with high enouth bias, of course)
maybe slightly less, cauz you can never output as much voltage as the poser supply rails, but it's still enough power woth 12V rails
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Your statement implies that you haven't measured the AX with the rail voltages you are referring to. Please refer to Nelson posts. I have measured it and I can assure you it doesn't come close to that.
 
#2,142
grataku said:


Your statement implies that you haven't measured the AX with the rail voltages you are referring to. Please refer to Nelson posts. I have measured it and I can assure you it doesn't come close to that.
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Quite right. 12 V rail and amp swinging to within 1 V of the rail gives 22*22/2/8 W which is some 30 W RMS. Peter's 15 V rails swinging to within the same volt gives 28*28/2/8 which is some 49 W which is what he claims to get.
 
#2,143
UrSv said:


Quite right. 12 V rail and amp swinging to within 1 V of the rail gives 22*22/2/8 W which is some 30 W RMS. Peter's 15 V rails swinging to within the same volt gives 28*28/2/8 which is some 49 W which is what he claims to get.
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I am finding lower power than that. Although all my instruments are uncalibrated I get ~30W at clipping on 8ohms with 15 V rails.
 
#2,146
Peter,

I think the 12V were chosen because Grey used them for his Mini-A developed X.
The problem with higer voltages is the power dissipation wich is even worse than with an Aleph (for the same output).

I don´t think the amp can swing to within 1V of the rail. My Aleph 5 comes to about 2V from the rail so with an X this should be about 4 volts.

I think it still good practice to see what power you need and if you need power into low impedances or not and layout the power supply accordingly.

william
 
#2,148
Peter,

there´s an excel file somewhere in this or the high power thread originally by me but improved with graphics etc.

It should be called "berekening1" or similar.

If you use this you can calculate all combination of voltage and bias you can think of (you can even use negative bias to cool your rooms in summer).

william
 
#2,150
ww
come on 800W is just the power consumed by a small hair dryrer! No big deal. 😉
I think that what Nelson was saying is that you get a cleaner 'burn' at higher rail voltages. All my toying with the circuit seems to confirm that.
In any case, getting down to below 15 V rails is not recommended.
 
#2,152
wuffwaff said:
Peter,

there´s an excel file somewhere in this or the high power thread originally by me but improved with graphics etc.

It should be called "berekening1" or similar.

If you use this you can calculate all combination of voltage and bias you can think of (you can even use negative bias to cool your rooms in summer).

william
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William,

Here is your original version:
 

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#2,154
Peter Daniel said:
What about all those 800 or so resistors that have been sold?😉 They only good for low rails. If not for source resistors at least they good at the output.

Recommended or not, I don't really see a problem with using this amp with 15V (or slightly lower) rails.
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Peter, don't get me wrong, I have been there, done that, listening to the AX with 15v rails and I am very, very happy. As a matter of fact, it's going to be a few months before the monoblocks are ready, it's going to be a scary prospect, and quite an investment in time and most of all money. I have estimated a $400 for the PS alone, the fets are going to be another $200, new set of MILLS, I don't even want to think about it.
The AX prototype is already a very substantial amp weighing in at ~30kg. I have already a place for this amp in my future bedroom system. The monoblocks are probably going to be 50kg each and they are going in my main system. They are just two different beasts.
 
#2,155
Power supply for Aleph X

I ordered some Aleph X board from Hifizen and wondered what type of power supply I should use ( I know that Mr. Pass said that a 25V rail would work fine) but since I am a little new to DIY audio I dont know how to build one that will give me good power and sound. If someone could help me find the schematic of a good power supply for the Aleph-X board that would really help me.

Thanks
 
#2,156
Heres a good question for the X Aleph experts.

The damping factor of the X Aleph must be higher due the use of feedback.

Has anyone calculated or measured this parameter?

I figure it must be higher than the stock Aleph from the subjective listening trials and would be a handy tip for the diy speaker building people as Rg (output impediance) has a marked impact on speaker total QTS in bass reflect designs

If it is sufficiently high, say over 250 @ 8 ohms then impact on QTS can of course be ignored.

Ian
 
#2,157
macka said:
The damping factor of the X Aleph must be higher due the use of feedback.
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No, typically the Aleph X output impedance is slightly higher than an Aleph. For both these designs as implemented commercially, the figure is in the ball park of 30 or so.

Of course it would be easy enough to increase the open loop gain and thus the feedback of either design to get higher damping factors, but we have not chosen that path.

The subjective difference in the bottom end is not due to damping factor, and this is true of the commercial X amps as well.
 
#2,158
oh my, almost 250.000 pageviews :bigeyes:

I'm on the moment also busy with an Aleph X, following Grey's design.
On the moment I have to wait for the rest of the stuff, trafo's heat sinks and the FET's :bawling:

but pictures are and will be taking of the project, but it will take a while 🙂
 
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