Aleph L v.s. Aleph L Rev 1.2 - diyAudio
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Old 21st June 2004, 06:58 PM   #1
LBHajdu is offline LBHajdu  United States
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Default Aleph L v.s. Aleph L Rev 1.2

I was just wondering if anybody had any opinions on the two versions of the Aleph L found in http://www.passlabs.com/pdf/aleph/al_serv_man.pdf The Aleph L Rev 1.2 is a very interesting circuit. But no one has built one yet most likely because it needs a stepped pot. Does anyone know what inspired the new topology and what the sonic differences are to the older always active version?
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Old 22nd June 2004, 12:59 AM   #2
LBHajdu is offline LBHajdu  United States
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A lot of people seam to be reading this post, yet nobody has an opinion. Maybe it would help if I posted small pics right out of the PDF to inspirer people to have a look.
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Old 22nd June 2004, 01:09 AM   #3
LBHajdu is offline LBHajdu  United States
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this is the 1.2 version
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Old 23rd June 2004, 09:24 AM   #4
uli is offline uli  Austria
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Default Re: Aleph L v.s. Aleph L Rev 1.2

Quote:
Originally posted by LBHajdu
Does anyone know what inspired the new topology and what the sonic differences are to the older always active version?

Hi LBHajdu,

As it is common knowledge NP is a follower to Albert Einstein

"As simple as possible....."

You simply donīt need active circuitry at a gain below zero.

Therefore not even one active (polecreating) device is in the

signal path anymore!

Something that isnīt there cannot colour the sound!

Uli

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Old 23rd June 2004, 01:07 PM   #5
LBHajdu is offline LBHajdu  United States
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Well there may be nothing in the signal path, however the gate of the first input mosfet will load it with a little capacitants. Some source outputs donít have the current to run passive. I wonder why this design was never used in any other pre-amps opting instead for always active circuits. I can,t even tell if its really passive below the 6th to last contact.
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Old 23rd June 2004, 01:26 PM   #6
uli is offline uli  Austria
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Default philosophy

In fact many sources are not capable of being run passive.

I think this design wants to be "best of both worlds".

If its really passive or not, is a philosophical question

similar to "is Aleph really SE or not?"

Uli

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Old 23rd June 2004, 03:30 PM   #7
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I built both versions some 2 years ago.
As I remember I liked first version (all time active) much better.
And indeed Aleph L is excellent preamp , especially considering number of parts used.Aleph P 1.7 sounds better still but I can see it is pretty much balanced version of Aleph L with added negative CCS.

Quote:
In fact many sources are not capable of being run passive.

I think this design wants to be "best of both worlds".

If its really passive or not, is a philosophical question

similar to "is Aleph really SE or not?"
I'm not that wizz at knowing these topologies.It seems to me that untill some point second version works purely as an passive attenuator.If this is true I don't see the point of using it as in my expirence active preamp always sounds better than passive (especially driving Alephs).
There might be enough gain but there are other factors that make passive attenuators sound worst than good active circuit.

Bartek
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Old 23rd June 2004, 09:24 PM   #8
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Default Aleph L

I agree with zygibajt.

I have built both versions of Aleph L and I think the original version sounds livelier, more dynamic with more control in LF and with more presence in the midband.

The only "drawback" is that it is phase inverting at the output but then I don't think it is actually a drawback.

Nick
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Old 23rd June 2004, 09:44 PM   #9
uli is offline uli  Austria
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Cool dependency

Normally a pre should not "sound" at all.

The reason why passive preamps tend to sound not as

"lively" as active ones is either the lack of coloration

or just poor quality of the source equipment. In most

cases the source is not capable of driving passive circuitry

and a powerstage.

Again I think this is a matter of philosophy, having lowest

possible number of gain devices in the signal path or not.

Uli

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Old 23rd June 2004, 10:08 PM   #10
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I must disagree Uli.

You are 10 times wiser in audio electronic and I admire your knowledge.

But in my expirence (tried many passive and active) active in 99% cases sounds better.And the only thing it looses with passive is a little liveness.Passive are always a bit lively and a tiny bit more natural.But they lack dynamic ,soundstageing and bass performance are very poor,and highs are dirty.

Less is better to some degree,but too less is not good.
Simple circuit like Zen or Son of Zen will never match more complex Aleph X or regular Aleph.

It's like with full range drivers.They are simple and in some aspect very very good,but if one is expecting a truly full range outstanding performance from top to bottom, there is no place for such simple solution like full range driver.

I think it is mostly impedance mismatch.The passive will never deliver such low output impedance as good active.

Bartek
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