Pass Aleph P 1.7 preamp builders thread

[blackdod]

Has anyone previously used the Aleph P 1.7 as a headphone amplifier?

I am using headphones with different impedances (25 to 600 Ohm, SE output/ground like "return"). The sound is good although I think that I need power especially with low impedance headphones.

I would like to add a headphone output on the front of my preamp and be able to use it as a preamp/HA at the same time.

 

[Danger Mouse]

I had the same Question. Have a spare P1.7 in my Basement. So i could use it as HPA. Maybe?

 

[Zen Mod]

try

 

[Bfpca]

You can try, but remember that the Aleph P is a current source output preamp with an attenuator on the output. The output impedance is about 2k ohms at full output and gets lower as the volume is attenuated.

 

[Erlend Sæterdal]

Would it be a problem to move the pot to the input? We did that at our BOZOZ in Copenhagen Hificlub. Have used it for 20 years now.

 

[Bfpca]

If you move the pot to the input then the output impedance will always be ~2k ohms.

 

[blackdod]

I've been using the Aleph P1.7 for a few weeks and the answer is that although it moves some headphones, it needs more power to move hard headphones.

With the full volume (and high gain) you will get acceptable listening levels... but only that.

A pity because this preamp has a delicious sound.

 

[AudioSan]

i use Aleph P1.7 as preamp for my whammy headphone amp.

 

[blackdod]

I have abandoned the idea of using the P1.7 as a headphone amplifier. Now I´m thinking is use the Aleph P1.7 and my A.C.A with a TSR connector.


I see no advantage in using two volume potentiometers (one before and one after the preamp). I prefer to use a pot. after the preamp and a other pot for P5 instead of 2K trimpot.

 

[TheChosenOne]

Hi, I am slowly progressing with my first DIY audio project. Since power supply and gain stage are ready, I think of using The δ1 relay-based R-2R stereo attenuator and The δ2 relay-based stereo input/output selector as attenuator and input/output selector respectively.
Can you please tell me what values for termination resistors and output load resistors (in input/output selector) are needed? Ultimately, this preamp should work with Aleph 2.

 

[scipio13031965]

Hello everyone, for the first time I connected an unbalanced source to my Aleph 1.7 so I shorted pins 1 and 3 on the XLR input socket and the sound is distorted, exactly the opposite of what is reported in the manual ..... ..suggestions??

 

[Erlend Sæterdal]

Cut to pin 3

 

[scipio13031965]

In your opinion, what is technically due to?

 

[Erlend Sæterdal]

There is only hot and ground from source. Hot to pin 2 and gnd to pin 1. Nothing to pin 3.

 

[Mark Allen]

Is anyone selling blank PCB's for the 1.7? I l know about Jim's Hifi.... but I like to try to avoid buying Chinese stuff... I built a P1.7 a few years back, but gave it to a friend that kept bugging me to build him one. It's time I build myself another one....

Thanks!
Mark

 

[scipio13031965]

ok, i will follow your advice even if the manual says to short.

 

[Erlend Sæterdal]

Aleph 1.7

PASS LABS CLONE - ALEPH P 1.7 DIY Preamplifier PCB layout

 

[scipio13031965]

I send emails but no one answers, I have seen the PCB but does not see the two 2k trimmers

 

[Erlend Sæterdal]

1.7

I will send you a picture of mine later today.

 

[Erlend Sæterdal]

Jim's Audio 1.7

Maybe not the best layout. But I just found this.

Aleph P lass A SE MOSFET pre-amp PCB one channel - JIMS Audio