I noticed something a bit curious when looking over the manuals for the (later) Aleph amps.
The Aleph 1.2 and 5 have the 4 ohm output at 1.5 times the 8 ohm output. But the Aleph 2 and 3 have it at twice the 8 ohm output. (The Aleph 4 manual does not specify a 4 ohm output. And, familiarly, all of then do poorly below 4 ohms, though the 3 is the only one that seems to specify a 2 ohm output.)
Is there a reason for this? To what extent would one expect it to make a difference when driving 4 ohm speakers? This does matter to me since (a) I have Dynaudio Contour 60s, nominally a 4 ohm load, and (b) I am about to take possession of a pair of Aleph 1.2s whereas my current amps are Aleph 2s (or VTL MB-185s).
The Aleph 1.2 and 5 have the 4 ohm output at 1.5 times the 8 ohm output. But the Aleph 2 and 3 have it at twice the 8 ohm output. (The Aleph 4 manual does not specify a 4 ohm output. And, familiarly, all of then do poorly below 4 ohms, though the 3 is the only one that seems to specify a 2 ohm output.)
Is there a reason for this? To what extent would one expect it to make a difference when driving 4 ohm speakers? This does matter to me since (a) I have Dynaudio Contour 60s, nominally a 4 ohm load, and (b) I am about to take possession of a pair of Aleph 1.2s whereas my current amps are Aleph 2s (or VTL MB-185s).
Rather than build a stock aleph, it will be best to build an Aleph designed specifically for your speaker load.
Otherwise just build an F6.
Or build a BA2.
These two will be closest to the aleph sound but with more grunt for difficult loads.
If you're not into building amps, then I will compare the differences.
I see you want to purchase an amp.
Otherwise just build an F6.
Or build a BA2.
These two will be closest to the aleph sound but with more grunt for difficult loads.
If you're not into building amps, then I will compare the differences.
I see you want to purchase an amp.
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Thanks for the remark, but I was specifically asking about the production Alephs. I should have been clearer about that. I've owned a 3, a 5, and two sets of 2s over the years---as well as both versions of the P, an Ono, an XOno, an XA-30.5, an XP-15, an XP-20, and both versions of the D1, and (as I said) I've just bought a pair of 1.2s. I intend to be buried with the 2s. So I'm a junkie, admittedly.
I've yet to try the .8 amps and certainly want to hear XA100.?s at some point. I'm guessing they would do amazing things to the Contour 60s.
I was motivated to think about the differences between the Aleph amps by the 2 vs 3 thread.
I've yet to try the .8 amps and certainly want to hear XA100.?s at some point. I'm guessing they would do amazing things to the Contour 60s.
I was motivated to think about the differences between the Aleph amps by the 2 vs 3 thread.
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You were clear, I just glossed over that detail.
I tend to go into autopilot mode given this place is diyaudio.
From memory the Aleph 1.2 is more beastly than Aleph 2.
Let me check though.
I tend to go into autopilot mode given this place is diyaudio.
From memory the Aleph 1.2 is more beastly than Aleph 2.
Let me check though.
Even a pair of Pass Labs XA60.8 are likely to be more suited to your speakers than any Aleph variation, but Aleph 1.2 is a beast and will have no issues driving your speakers.
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Hey, Pico.
I will eventually try XA-60.Ys or XA-100.Ys. But since I've owned almost all the (2-stage) Aleph amps, I've always been curious to hear the 1.2s in my own system. I heard them years ago at the Stereo Shop, then my local dealer in Arlington Massachusetts, driving the very difficult but also very wonderful Thiel CS7s. That was 25+ years ago.
But I distinctly remember my friend there, Paul Chambers (now at Goodwins High End), telling me about taking the 1.2s to the house of one of their really rich customers who had top of the line Krell Audio Standard amps. (They were also Krell dealers.) His response was: "Take these Krell amps away. After hearing the 1.2s, I don't want to hear them ever again." (I myself had a Krell KSA-80B before my first Pass amp, an Aleph 5. But I'd not be quite so dramatic, and if you need serious power, then I'd heartily recommend the KSA-80B, if you can find one.... It does like 800W into 1 ohm.)
There are a couple sets of XA-100.?s around, but the 1.2s are so hard to find I figured I'd grab them while I can!
PS The Aleph 4 really is unobtanium.....
I will eventually try XA-60.Ys or XA-100.Ys. But since I've owned almost all the (2-stage) Aleph amps, I've always been curious to hear the 1.2s in my own system. I heard them years ago at the Stereo Shop, then my local dealer in Arlington Massachusetts, driving the very difficult but also very wonderful Thiel CS7s. That was 25+ years ago.
But I distinctly remember my friend there, Paul Chambers (now at Goodwins High End), telling me about taking the 1.2s to the house of one of their really rich customers who had top of the line Krell Audio Standard amps. (They were also Krell dealers.) His response was: "Take these Krell amps away. After hearing the 1.2s, I don't want to hear them ever again." (I myself had a Krell KSA-80B before my first Pass amp, an Aleph 5. But I'd not be quite so dramatic, and if you need serious power, then I'd heartily recommend the KSA-80B, if you can find one.... It does like 800W into 1 ohm.)
There are a couple sets of XA-100.?s around, but the 1.2s are so hard to find I figured I'd grab them while I can!
PS The Aleph 4 really is unobtanium.....
Is that really all there is to it? If so, how much point is there really in that? I've been told that there's an 18" diameter toroidal transformer down there in the 1.2 that accounts for a lot of its weight. Is that really worth a 20% increase in current?
Yeah, mostly that is all there is to it.
It's the same amp topolgy.
Aleph 1.2 will sound different but not a lot different than Aleph 2.
But you will be able to tweak the sound a little bit.
I think the AC current gain is not that different between the two although I can check it.
The Aleph 1.2 will be an improvement most likely in transparency and grunt over the Aleph 2 that you will feel, so you should experience ownership of the 1.2.
It's the same amp topolgy.
Aleph 1.2 will sound different but not a lot different than Aleph 2.
But you will be able to tweak the sound a little bit.
I think the AC current gain is not that different between the two although I can check it.
The Aleph 1.2 will be an improvement most likely in transparency and grunt over the Aleph 2 that you will feel, so you should experience ownership of the 1.2.
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Gain isn't a big deal for me. As Papa says in the B1 manual, we mostly have plenty of gain elsewhere, and I definitely do.
Yeah cause it also has higher voltage secondaries.
This is why a custom made approach will nearly always be better than an off the shelf approach.
Especially true for the Aleph Circuit.
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I would get the 1.2 and enjoy it, at some point get in a pair of XA60.8 mono blocks for audition while you still have the Aleph 1.2, then make your own judgement.
You may in fact still prefer the Aleph. It is a beautiful amp after all.
You may in fact still prefer the Aleph. It is a beautiful amp after all.
I suppose, then, that it would have been *possible* to produce an amp that did 200W into 8 ohm and 400 into 4 ohms, if we beefed up the power supply enough. But it was decided not to do that. I'm curious why.
It's more to do with the current limitations of the amp circuit.
You either have to decide whether you will design for an 8 Ohm nominal load or a 4 Ohm nominal load.
However if you design for a 4 Ohm nominal load, the marketing department will complain the power into 8 Ohms is not very high and the zombies will think it is somehow inferior.
Depending on AC current gain the Amp will current limit somewhere between 1.25 times and 2 times the bias current.
So you have to make a decision which way to go regarding biasing for a nominal load, or the heatsinking starts getting astronomical in size, if you try to increase both voltage and current ratings of the amp.
The XA amps don't have these problems to deal with, to the same extent, once they go beyond their Class A limit, they keep going and transition into AB, so difficult loads are less of a problem for the XA amps. So the XA amps are more limited by the power supply capability, and to a lesser extent the number of mosfets in the output stage which is already overkill.
Having said all that 12A is a lot of bloody current, so you should be fine.
You either have to decide whether you will design for an 8 Ohm nominal load or a 4 Ohm nominal load.
However if you design for a 4 Ohm nominal load, the marketing department will complain the power into 8 Ohms is not very high and the zombies will think it is somehow inferior.
Depending on AC current gain the Amp will current limit somewhere between 1.25 times and 2 times the bias current.
So you have to make a decision which way to go regarding biasing for a nominal load, or the heatsinking starts getting astronomical in size, if you try to increase both voltage and current ratings of the amp.
The XA amps don't have these problems to deal with, to the same extent, once they go beyond their Class A limit, they keep going and transition into AB, so difficult loads are less of a problem for the XA amps. So the XA amps are more limited by the power supply capability, and to a lesser extent the number of mosfets in the output stage which is already overkill.
Having said all that 12A is a lot of bloody current, so you should be fine.
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One major difference between Aleph 1.2 and Aleph 2 is that 1.2 has 12 mosfet pairs (24) in the output stage, Aleph 2 has 6 pairs (12).
That will be an audible effect.
That will be an audible effect.
It must be some kind og magic. Getting a 18" transformer in to a chassis that measures 16.5"x16.5"x10.5". and a good 2" on 4 sides are heatsinks. that leaves 12,5"x12.5"x10.5". No the transformer in Aleph1.2 is about 1.2KVA and around 7" diameter i would guess.
The original XA used the Aleph output stage and so cannot transition to class AB,
while the later .5 and .8 series can.
The Aleph 4 seems to be quite rare. I seem to recall Papa mentioning it was
requested by overseas dealers who wanted a big stereo 100Wpc amp. I believe
to keep its size somewhat manageable it was biased lower than the Aleph 2 and
probably not designed for lower impedances.
while the later .5 and .8 series can.
The Aleph 4 seems to be quite rare. I seem to recall Papa mentioning it was
requested by overseas dealers who wanted a big stereo 100Wpc amp. I believe
to keep its size somewhat manageable it was biased lower than the Aleph 2 and
probably not designed for lower impedances.