PV12 Preamplifier

[arold19]

Hi, I want to know what you think about making a Conrad Johnson PV12 preamplifier???
I am plannig to make only the line stage, not the phono, so the schematic is a lot more simple...
But I have a couple of question for you, maybe you can answer me:

Here is the schematic:

http://www.drtube.com/schematics/cj/pv12.gif

1-What is the voltage output my transformer need to have, and how much current ??
12AU7 need 12v for the heater, but how much for the power supply ????

2-What transistor car I choose to replace the MPSU10 and the MPSU60 ???

3-What mean (pp) and (ps) near the capacitor on the schematic... pp=electrolytic and ps=poly????

4-It is writing (VTR52) and (2N65) on some resistor, what that mean ???


Thank you!!

[Shoog]

Have you heard this circuit ?
I personally think you could easily better it with a better design.

Shoog

[analog_sa]

Originally posted by arold19

1-What is the voltage output my transformer need to have, and how much current ??
12AU7 need 12v for the heater, but how much for the power supply ????

2-What transistor car I choose to replace the MPSU10 and the MPSU60 ???

3-What mean (pp) and (ps) near the capacitor on the schematic... pp=electrolytic and ps=poly????

4-It is writing (VTR52) and (2N65) on some resistor, what that mean ???


Thank you!!

1. Reg voltage is 330v so raw dc should be at around 380- 400v.
AC 280v/100mA should be enough.

2. Anything that can take 600v/50mA

3. Polypropylene and polystyrene

4. RN65, VTA52 - Dale


Why on earth would you want to build it?

[arold19]

I know it is a very good sounding preamp.....

Shoog: you have an other good sounding preamplifier design for me???

thank you for your answer!

[Johan Potgieter]

Arold19,

Sounds like pouring cold water over enthusiasm (and I respect the Conrad Johnson name), but this is really an overdesigned effort if ever I have seen one, in the power supply department.

You are justified in asking for an alternative, which I cannot post right now - apology. If Shoog does not come up with one, I will try to post something (must draw, scan). My main concern is that there is nothing to justify the power supply complexity of the C-J design. An ordinary well-designed circuit (twin triode or triode-pentode) without any power supply regulation should be adequate for a line stage.

Regards

[arold19]

Ok.... Thank you very much... I'am waiting for an other design... I found that the power supply was complex but I think that it is a sign of quality...

I appreciate if you can post a good design !!! An if the part are easier to found than the PV12, it will be perfect for me.

[Zen Mod]

one of best and also simplest preamps here .........

Yet another 12B4 line stage, or is the 12B4 better than the Grounded Grid.....


or


http://www.diyaudio.com/forums/searc...der=descending

[arold19]

Ok, this 12B4 preamp will sound better than a 2K$ stock preamp ???

If you are sure, can you give me a good, or very good power supply schematic, and I will begin the preamp right away!!!

The schematic on the 1st page of the 70 page tread is the good one ??

Thank you... It is very cool !

[Zen Mod]

Originally posted by arold19
Ok, this 12B4 preamp will sound better than a 2K$ stock preamp ???

If you are sure, can you give me a good, or very good power supply schematic, and I will begin the preamp right away!!!

The schematic on the 1st page of the 70 page tread is the good one ??

Thank you... It is very cool !

look for my posts in that thread ;

in fact- re-read entire thread and ask what (if ) you don't get .


regarding 2K preamp .........

show me 3 good junkyards ( to find few parts) and I'll make for nothing preamp better than stock 2K preamp ;
it's matter of knowledge and DIY,not shiny knobs and parts made of preputium

edit:
click on my www button and look for WOT preamp page ;

too lazy to took present state pictures ( just from prototype era) , but there you can see pics of preamp which made me pretty comfortable regarding price competitions

[Shoog]

I took my FVP5 clone to a local DIY meet last week and it was the best one there. Could easily be built from salvaged parts for less than a $100.00
If you are really interested then send me an email and I will send you the schematic.

I feel certain that you are right about this amp sounding good - but it seems to have one or two fundamental errors of design which would be holding it back. The choice of a cathode follower final stage is a huge no-no for me. If you search this forum on this subject you will find that this approach is almost universally disliked around here. Make your choices but know why you are making them, a bit of basic research will pay huge dividents in the end.

Shoog