Aleph P1.7 modification

[BRunenr]

Here is my new preamp. It is modification of Aleph P 1.7. I would like to use power supply from my BLSOSOZ, eliminate input capacitors, use CC sources as in Aleph P and use 40mA bias as in BLSOSOZ. Please send me your suggestions.

Sorry for my bad english.

 

[BRunenr]

Schematics

 

[jam]

You could try replaceing the active drain loads on the differentials with a cascode. Might make a good experiment to see which sounds better sonically.


Jam

 

[Peter Daniel]

Is it just the schematic you've done or you checked your P1.7 working with the modifications? I was wondering what sonic difference removal of feedback resistor makes? But if nobody's gonna answer that question I will check it myself because I'm halfway through with my Aleph preamp. And who said that the footprint is quite big?

 

[jam]

Peter,

Sorry! Are you talking about the resistors hooked from the drains of the differential to ground?

Jam

 

[Peter Daniel]

No jam, you OK.
I was just curious if the resistor from drains to input have any sonic effect? Because if not, I wouldn't place in a circuit. As you see I don't have too much space available.

 

[jam]

I see you were refering to a different thread, the resistor might supply a little feedback but it's main purpose is to bias the mosfet on. I don't think the circuit will work without that resistor.

Jam

 

[BRunenr]

HPotter,

no it's only schematic, I'm working on prototype now.

jam,

this circuit should work, gate of gain FET is at zero potential and source at -4V as in BLoSOZ, because I use +60V/-60V power supply. So I can omit bias resistor and input capacitor.

 

[jam]

Brunner,

I ment the original Aleph 1.7 that used a single ended supply. Your circuit should work fine.

Jam

 

[PMA]

Preamp

Brunner,

I do not see any input capacitors. Did you mean output capacitors? Is there any serious reason to remove them?

Regards,
PMA

(your reply in czech would be appreciated, too )