6N1P preamp too much gain...

[JojoD818]

Hi Dave,

I would really love to know what your friend's preamp sounds like.

Regards,
JojoD

 

[planet10]

I would really love to know what your friend's preamp sounds like.

The linestage (ie 12B4 buffer to drive the cable) is still in the parts gathering phase, but the phono stage does quite well. It starts loosing it in the high freq and the dynamics department when you hook it up to drive cables and the passive attenuator at the front of the power amp, and when connected to his current LS (a foreplay) you gain that back, but at the expense of some (euphoric) coloration. The thing has enuff power supply for a modest power amp which really helps it along.

dave

 

[planet10]

And the PS -- all Solen caps.

dave

 

[planet10]

and what it looks like -- we'll move the phono board abit, which will give us the room we need to pop a couple 12B4s at the back.

dave

 

[fdegrove]

Hi,

Dave,


Nice job.
You're probably already aware of it but the bottom diode for the heater supply is reversed biased on the schem.

Cheers,😉

 

[planet10]

You're probably already aware of it but the bottom diode for the heater supply is reversed biased on the schem.

No, i'd actually missed that, don't know if it was my mistake or just blindly copying the hand drawing...

Thanx... fixed now.

dave

 

[s2kov]

Many thanks....

Hi,



If you want to use both sections in // the anode resistor and cathode resistor will need to be half the value indicated.

Cheers,😉

 

[JojoD818]

Dave,

That is a veeery nice gear you got there. May I know what power transistor was used for the capacitance multiplier in the heater supply? I plan on experimenting with heater psu.


Thanks!
JojoD

 

[fdegrove]

Hi,

May I know what power transistor was used for the capacitance multiplier in the heater supply? I plan on experimenting with heater psu.

Probably a high current NPN Darlington....With 10.000µF in the tail it should mimmick a battery supply quite well.

Cheers, 😉

 

[planet10]

That is a veeery nice gear you got there. May I know what power transistor was used for the capacitance multiplier in the heater supply? I plan on experimenting with heater psu.

Not my preamp... i'm not sure what he used... It is actually a series pass regulator IB.

dave

 

[fdegrove]

Hi,

It is actually a series pass regulator IB.

That + a capmultiplier.

A while ago I posted the equivalent of it but using tubes for a higher voltage B+ as it was used by Studer Revox in a preamp.

Here's one I use as a second regulator and capmultiplier for a 24VDC 300mA supply.

Cheers,😉