Which pass preamp for unbalanced in/out ?

supernet · 9th February 2005, 11:50 AM

For driving unbalanced power amplifier, which of these preamps is better option? Sound quality is very important.

Aleph 1.7 or Aleph L

Thanx

azira · 9th February 2005, 03:34 PM

What exactly is a passive preamp?

Basically it's an attenuator right? as in a potentiometer?

I suppose then that there are several very high quality stepped attenuators (the chipamp evangelists all use them). Or you could choose to go with a relay powered resistor ladder and then it's a matter of resistor quality.
--
Danny

hifimaker · 9th February 2005, 05:40 PM

Hello Supernet,

Personally I like the Aleph P for what you are trying to do. There has been a lot of discussion in the forum about using a BOSOZ or Aleph P verses a Passive preamp.

There is a wonderful warmth and romance to the sound when using one of the Pass active preamp circuits. If you use a balanced source and an unbalanced amp, you should expect great results.

Good luck,

-David

eLarson · 9th February 2005, 06:02 PM

I don't know where "passive" came into the conversation. But I'm going to ignore the binary choice of the original question and recommend a BOSOZ.

You can delete the drain resistor and associated components on the non-inverting input's MOSFET since you are going to use a strictly single-ended in to single-ended out. Take the output from the other MOSFET's drain. And ground the inverting input.

Presto: signal goes in one side, comes out the other side noninverted.

azira · 9th February 2005, 06:44 PM

Looks like I should just eat my words for lunch today.. I misinterpreted the title to mean passive instead of Pass. Sorry folks. Too much time reading the chipamp forum I guess.
--
Danny

hifimaker · 9th February 2005, 11:02 PM

Hi Azira,

Don't feel too bad.... The Aleph L is a passive Preamp until the attuenator is set to about 75%, then the active components kick in.

Most people who have an Aleph L use it as a passive preamp.

Here's a link to the L's description.

http://www.fullswing.com/passlabs/alephl.html

-David

supernet · 10th February 2005, 11:33 AM

Thanks for reply.

I was thinking that Aleph P 1,7 Susy concept will not work so good with unbalanced inputs and outputs as balanced. So my idea of Aleph L come in.

Anybody knows when X2 service manual will come? Mr. Pass said that it should come out to the end of last year. I am a little bit impatient

hifimaker · 11th February 2005, 08:46 PM

Hi Supernet,

I asked earlier about the X2 Service manual... Here's Nelson's reply. Essentially he is waiting for patient approval for the attuenator.

Any word when the Pass X2 preamp Service imanual is available?

-David

9th February 2005, 11:50 AM	#1
supernet diyAudio Member Join Date: Dec 2001 Location: Europe	Which pass preamp for unbalanced in/out ? For driving unbalanced power amplifier, which of these preamps is better option? Sound quality is very important. Aleph 1.7 or Aleph L Thanx

9th February 2005, 06:02 PM	#4
eLarson diyAudio Member Join Date: Aug 2002 Location: Gaithersburg, MD	I don't know where "passive" came into the conversation. But I'm going to ignore the binary choice of the original question and recommend a BOSOZ. You can delete the drain resistor and associated components on the non-inverting input's MOSFET since you are going to use a strictly single-ended in to single-ended out. Take the output from the other MOSFET's drain. And ground the inverting input. Presto: signal goes in one side, comes out the other side noninverted. __________________ Would a woodchuck bother to chuck MDF?

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9th February 2005, 03:34 PM	#2
azira diyAudio Member Join Date: Dec 2003 Location: Near Seattle	What exactly is a passive preamp? Basically it's an attenuator right? as in a potentiometer? I suppose then that there are several very high quality stepped attenuators (the chipamp evangelists all use them). Or you could choose to go with a relay powered resistor ladder and then it's a matter of resistor quality. -- Danny

9th February 2005, 05:40 PM	#3
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Hello Supernet, Personally I like the Aleph P for what you are trying to do. There has been a lot of discussion in the forum about using a BOSOZ or Aleph P verses a Passive preamp. There is a wonderful warmth and romance to the sound when using one of the Pass active preamp circuits. If you use a balanced source and an unbalanced amp, you should expect great results. Good luck, -David

9th February 2005, 06:44 PM	#5
azira diyAudio Member Join Date: Dec 2003 Location: Near Seattle	Looks like I should just eat my words for lunch today.. I misinterpreted the title to mean passive instead of Pass. Sorry folks. Too much time reading the chipamp forum I guess. -- Danny

9th February 2005, 11:02 PM	#6
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Hi Azira, Don't feel too bad.... The Aleph L is a passive Preamp until the attuenator is set to about 75%, then the active components kick in. Most people who have an Aleph L use it as a passive preamp. Here's a link to the L's description. http://www.fullswing.com/passlabs/alephl.html -David

10th February 2005, 11:33 AM	#7
supernet diyAudio Member Join Date: Dec 2001 Location: Europe	Thanks for reply. I was thinking that Aleph P 1,7 Susy concept will not work so good with unbalanced inputs and outputs as balanced. So my idea of Aleph L come in. Anybody knows when X2 service manual will come? Mr. Pass said that it should come out to the end of last year. I am a little bit impatient

11th February 2005, 08:46 PM	#8
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Hi Supernet, I asked earlier about the X2 Service manual... Here's Nelson's reply. Essentially he is waiting for patient approval for the attuenator. Any word when the Pass X2 preamp Service imanual is available? -David

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