The Aleph-X

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#442
iwahn said:
MEnsing,
I did try with two transistor-pairs at the outputs, but as this resulted in some loss in detail and clarity, I desided to change it back to the original and wait for someone on the forum to present a solution for this problem.

This circuit performs-in my opinion, better than an Aleph 3, with a more detailed soundstage,
and an absolutely amasing bass, very deep and defined.
😉
Click to expand...

Did you increase the bias for two- pairs so it was similar per device as using on pair?

Are you saying that this circuit has much better bass than Aleph 3?
 
#443
Peter Daniel,
With two- pairs output the bias was in the order of 1.5 A
( 0.5V across 0.33 ohm Source-resistors) This is less current per device. With one pair outputs it is 2.27 A (0.5V across 0.22 ohm)
This circuit has absolutely better bass than my A3 clone.
 
#445
It has been my experience with Mosfets that the total
bias is the key element to performance. Within reasonable
limits it can be through 1 device or distributed through
parallel devices, but the total remains the prime factor.

Too few devices and you might cook the parts. I like to
stay around 25 watts or less, but I have successfully used
the IRF 150 watt parts up to 50 watts without seeing
many failures.

With more devices, it's easier to get the current up there,
but you reach a limit in the amount of capacitance you
want to try to drive. Practically speaking, for something
like an Aleph circuit, this limit is less than 12 devices in
parallel, and usually I prefer half that.

Within those boundaries, if you want the best performance,
you crank the bias up all you dare.
 
#447
Mr. Pass on the Aelph 1.2 you include very little in the way of specifications in the manual, unlike say, the Aelph II which has all sorts of information. Since all the Aelph topologies are essentially the same is it fair to say they all sound the same? I was thinking of building the Aelph 1.2, but clarity in is very important too me and the Aelph II may offer more due to less Transconductance in the output stage.

Did I get that right? 🙂

Anthony
 
#448
I tried to double the transistors on the output mostly for sharing the load over more devices. The PSU is +/- 15v.
Click to expand...

With two- pairs output the bias was in the order of 1.5 A
Click to expand...

I agree with Peter and that the lower bias was causing the loss in detail and clarity. I think that if you want use more output devices you MUST increase the bias current.

Thinking about this problem the dissipation per device question came up to me. According to Nelsons answer

Practically speaking, for something like an Aleph circuit, this limit is less than 12 devices in parallel, and usually I prefer half that.
Click to expand...

If I am right the 6 devices in parallel equals the Aleph 2 schematic.

I still think that it should be not an problem to make an Aleph-X with 12 devices per side (4 times 6 devices parallel). I think I can say again

I have a dream
 
#449
The Alephs do not all sound the same. The bigger they
were, the better the bottom end, but the less detail
on the top. It is a fairly minor thing, and many people
preferred some of the character I would perceive as
flaws. My personal favorite is the Aleph 2.
 
#450
My personal favorite is the Aleph 2.
Click to expand...

Thanks for your feedback Mr. Pass, I think I will stick to building a pair of Aelph II's next. 🙂

I felt the upper end detail may suffer a bit in the Aelph 1.2 but the allure of 200 WATTS of SE CLASS A power is intoxicating. i am currently running a Rotel 1080 200WPC into my System Audio 3070's a 4 OHM load (Manufacturer claim). They are not particularly effecient, about 91dB, but I can easily drive them to 105 dB or so. I listen to a lot of classical from the Baroque period, I love to listen around 90dB, average wieghted of course.

Here comes the erroneous question you have been dreading since I said Thanks for your feedback, 🙂

Would you say that an Amp capable of SE Class A at 100 Watts would fair at least as well as the big Rotel under the conditions I have outlined above?

If you could stop laughing just long enougth to answer my question as best you can, I would feel so much better about asking such a loaded question in the first place.

Anthony
 
#459
Nelson ,

Thanks for your reply. In your reply to my question about the amount of output devices to use you wrote

My personal favorite is the Aleph 2
Click to expand...

I assume that mean the favorite from the Aleph series. If I am right that the XA-200 should leave the Aleph 2 far behind!

So, your favorite amount of output devices is 12. Since the Aleph -X has an Aleph back end I assume that your favorite amount of output devices for an Aleph-X is 24.

I was hoping on some encouraging noises from you when I anounced my plans for building an Aleph-X with the amount of output devices per side used in an Aleph 2. You didn't answer all my questions directly but somewhere between the lines I read that my assumptions are correct and that you say "go for it".
 
#460
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