• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Precision Fidelity - C7 Mods...help Wanted!

I have a Precision Fidelity C7 - in basic unmodified form. I want to bring it up to its highest spec. and would be grateful if anyone has a schematic to share for the 7A or REVISED model.

I will be using it with a Bent Audio MC Tx.(Silver) and a variety of power amps.

I will be very pleased to hear from anyone who has worked on this Pre.

Many thanks

Brian
 
Very many thanks Hermann. That is just what I wanted!

Anyone got experience of these pre-amps? I had the C9 many years ago and wish that I still owned it!! I can't even remember where it went to, but do remember that the power supply was always causing problems when using a voltage drop transformer which gave as little as 110vac. But it DID sound good with an old Moscode!

Brian
 
Precision Fidelity C7 Preamps (All Versions)

To All;
I am so sorry, but I am reluctant to give out the schematics for the 3 variants of the Precision Fidelity C7 preamp.

You see, a while back a guy asked me for the schematics for the Sound Valves VTP-101i preamp and the VTA-70i amp.
Being a nice guy I emailed them to him to help out another tube sound fan who said he wanted to do a few mods.

Now the ******* is out there on eBay selling copies of them!!
I'm sure you all know who I am talking about!

He actually had the nerve to contact me and ask for copies of my Precision Fidelity C7 preamp and M7 amp schematics.

Well, I don't sell schematics because they really aren't mine to sell, and it just isn't right.
I am more than happy to give copies of them to a true person needing help on these out-of-production units.

So there's the dilemma...
Now that I have been ripped off I don't know who I can trust.

I really want to help, but I just don't know how I can.

Sincerely,
-Pat
 
Hey patferrari, maybe you should just post the schematics in this thread so that no matter what they would be free, then if someone actually sells them on ebay they won't get away with it because no one will buy them.

The schematic I really need is for the C-8, but I may change it to the C-7 design since the one I have is not in all that great of shape electrically.
 
CrazzyAbtTubes said:
Hey patferrari, maybe you should just post the schematics in this thread so that no matter what they would be free, then if someone actually sells them on ebay they won't get away with it because no one will buy them.

The schematic I really need is for the C-8, but I may change it to the C-7 design since the one I have is not in all that great of shape electrically.


That's kind of my take on it also.Put the schematics out in the public domain,free for everyone to find.
These people selling schematics,and forcing people to take them down so they can sell their copy (*Cough*Heathkit*Cough*) ....Irritates me to no end. :mad:

I've started hoarding schematics,and am glad to share any that I have with anyone that needs it. :smash: Unfortunately,I don't have the C-7/8 diagrams.
 
That's kind of my take on it also.Put the schematics out in the public domain,free for everyone to find.
These people selling schematics,and forcing people to take them down so they can sell their copy (*Cough*Heathkit*Cough*) ....Irritates me to no end.

I am glad to have some agreement with this issue, because the way I see it is if I don't get the schematic, I make my own and post them with my projects "It's free use it, modify it, share it, I can't care less, but if you fake it copy it and sell it for some insane price, shame on them!" And will take note of them and spread the word "the schematic is free and of no value to ebay!!! :cuss: "

That is how I see it, any ways this has nothing to do with the topic even though it is a serious problem and I will see if I can get the schematic from poor old pat who was preveously deceived. :angel:


If not... then I shall do my work and draw up a schematic for the C-8 at the very least, and at the rate I am going I will have pages of schematics that no one knows exist, one being the LXI amplifier schematic, which needs an update. :rolleyes:
 
Look! The C8 schematic!

Well here it is! I did say I was going to draw it and hey, it wasn't too hard but took a while.

Note, I did not draw the power supply because there is another one that I would use if you plan to build this preamp, and it is basically the same design.

This is the first stage (Phono) so enjoy!
 

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C7 for C8?

I always search for a schematic of this preamp but can only find the one on that site that everyone disagrees with.... I don't understand it looks like it would work just fine, the concept is strange but will it work right if I built it from scratch?

It is rather frustrating that everyone complains and brags about this preamp yet no one tries to make a revised rebuild. :worried:

I completely rebuilt the C8 from scratch, I think I used the power supply from the C4 .... worked just as well and I slapped the regulators down to a massive heat sink solving the heat failure problem but changed the sound in my opinion.

I will make a bargan with someone, if they are willing to send me the true revised version of the C7 (does not need to include the power supply as I can make my own), I will send them all of the C8 schematics along with pictures and parts info. :cheers:

I am building an all out preamp and want to use the best RIAA stage I can find and the C7 stands out from all others. :up: