Which Aleph?

[Fixxer]

Hello from the land of the thousand lakes!

Since this is my first post, perhaps I should shed a light on how I ended up here.

It all begun a while ago when I had the opportunity to purchase a pair of speakers I had long lusted for, a pair of Apogees. So now the decisive step into the world of a more serious approach to reproduction of music was taken (this purely compared to my previous attempts that is), no turning back now.

Anyhow, the next step was choice of amplifier. Right from the beginning I had my mind set on bi-amping (passive to begin with) and class A amps. The speakers, Caliper Signatures btw, called for 200W per channel into 4 ohms, so 4 channels of 100W each should do the job. And then came the big UH-OH. No way I could afford that amount of wattage in form of Pass´s, Threshold´s, Forté´s or Classé´s etc.

Would I have to settle for AB amps.....,hmm I wonder what is available as diy? After all, my brother has a degree in EE, perhaps I could persuade him to build something for me. Let´s see what Google finds. Type diy class-a amplifier. Search results: 3rd result: www.passdiy.com. WHAT? Are Pass amps diy? So, long story short, here I am wondering which Alephs would suit my needs, and how they should be set up for best match with my speakers.
Aleph 5´s or 60´s perhaps?

Here´s the specs:

Recommended power: 100W/ 8 ohms, 200W/ 4 ohms
Nominal impedance: 3 ohms (in review 3.5 average, fluctuated between 3.2-4.2 ohms, so almost purely resistive)
Sensitivity: 84dB/3m (in review 82dB 1W/1m)

TIA!

[uli]

Build Aleph 2s

Uli

[Nelson Pass]

Unfortunately, I have to suggest that you try something else.

We have a pair of Apogees here (Stages) and none of the
Aleph amplifiers gave satisfactory results. The Aleph 0 is
good up to about 150 watts into 4, and that was the closest
thing to it, but that was a 3 stage amplifier, unlike the later
Alephs, which were only 2 stage.

Of the www.passdiy.com projects, the A75 is the most capable,
and should do an adequate job. You can toss an extra couple of
volts on the supply if you want, and the output stage will drive
2 ohms without burping.

[rwagter]

Apogee's he....

nominal impendace 3 ohms, that means even lower at some frequencies. Combined with a low sensitivy --> absolutely aleph 2 !

ralph

[GRollins]

Or boost the bias current.

Grey

[paulb]

Originally posted by GRollins
Or boost the bias current.

Grey

And bigger the heatsinks.

Hi Grey.

[Fixxer]

uli, rwagter:

Wouldn´t an Aleph 2 be a little overkill for bi-amping?

Mr. Pass:

Boy, that was discouraging.....I suppose You tried bi-amping also?
The common consensus on the AAUG forum was that Aleph´s (3 in particular) were discribed as divine on the MRTW, but not so for the bass panel. There the X series was favoured. Although some reported good results when driving the bass panels with the bigger Aleph´s. So the bass seems to be the problem for the Aleph´s.
BTW, what´s the A75´s output into 4 ohms again, I can´t remember reading it anywhere.

Grollins, paulb:

And one which Aleph do You suggest this should be done?

[Mattyo5]

If you are looking for that kind of power into 2-4 ohms, you are going to need aleph 2's that have a lower rail voltage....maybe +-35v supply, and upping the bias current, so you'll be looking at more like 50-75watts into 8 ohms, but closer to 150-200 into 4. I don't know the math, but assuming heat is the same, thats what you'll be looking at doing in order to get 150-200 watts pumped into those speakers...this means a LOT of heat total. You'll need to get rid of 1200 watts of heat...possibly more. Go for it dude!

-Matthew K. Olson

[Blues]

If you're ready to heatsink some serious heat maybe you can try for an Aleph 2 SuperCharger...more later.

[GRollins]

You're talking to a charter member of the Lily Guilder's Society, members of which are unable to leave well enough alone. That translates as me having altered every Aleph I've built in one way or another. The 2s I've got are about as close to stock as I come, although I grafted the 60 front end onto them and enriched the bias by 10 or 15%, then water cooled them. The Mini-A and Aleph-X were obviously well off the beaten path. That said, I'd take the 3 and flog it as hard as I dared. From my perspective, it and the 2 are the nuts.
Paul,
Howdy, fella. I still might move up there in order to get away from the insanity down here. I have new horror stories of life here in the sunny South. On second thought, perhaps I won't tell. It'll give you nightmares.

Grey