Tube Mic Preamp Schematic

[Daver]

Does anyone have or know where I can get a schematic for a complete vacuum tube preamp for a microphone? Essentially I want to build a channel strip for my brother to use with his home recording studio. Anything classic or something you've built or tried would be great. Thanks.
Dave

[Enzo]

Try entering this in google:

rca mic pre schematic

The top hit is one-electrons site with a ton of schematics, not all RCA by the way

ANd www.waltzingbear.com also has a number of nice tube circuits for mic pres.

[Sock Puppet]

Paia have a schematic and a kit here:

http://www.paia.com/PAIA/tubestuf.htm

and there are upgrade suggestions here:

http://www.tapeop.com/magazine/bonuspdfs/paiamicpremods.pdf

Looks a nice project.

S.

[Daver]

Thankyou both. I'll look over those areas. Does anyone have any recommendations for one particular model? I just want to pick a good one. ;)
Dave

[Guitarist]

Well, I love where you're heading. You might want to shortcut to these two items:

A telefunken tube mic clone (there's a tube preamp right there built in)
http://www.apexelectronics.com/pdfs/smapex460.pdf

Upgrade above with a upgrade capsule $100 and output transformer $50. But regarding the transformer I'm considering just having a bypass option by adding a female 1/4 out to plug into a line in. Why not?
Anybody?
With these extra matching transformers it seems akin to multiple A/D D/A conversions in series. It's not balanced but unless it's live you've got a low Z singal you're only traveling a short distance.

paired with a 12ay7 two tube preamp by EH
http://www.musiciansfriend.com/product/ElectroHarmonix-12AY7-Tube-Microphone-Preamp?sku=181127&src=3SOSWXXA

You WILL have amazing tones assuming the best downstream.

I'd yet to see a schematic for the EH though I took mine apart and seen it was very well made.

I have a Fear#n preamp schem if anybodys interested here that I made up while having one for a short while. Alot like a JCM 800 but way low gain. Amazing unit reminding me Sondano build quality.

Edit: having trouble uploading the pics. Says it's not a valid image file, which it is. Dang!

[Enzo]

It's only valid if it is one of the types this board allows. Can we post images here? I thought we had to link to files elsewhere.

[Sock Puppet]

I found a variant of the Altec 1566A via ePanorama

http://www.epanorama.net/links/audiocircuits.html#tube

Here's the Altec link:

http://www.tangible-technology.com/tubes/1566/1566.html

Enjoy,

S.

[Steve Conner]

Yes, you can post images using the "Manage Attachments" button below the box where you type your post.

Regarding the transformer thing, some people would say that a lot of the sound of tube mics and vintage preamps is really the harmonic distortion and frequency response anomalies caused by the audio transformers in them. I heard that the old Telefunken tube mic pres had some strange and wonderful iron in them, including a complicated choke that got degraded every time you plugged a mic in with the phantom power on. I don't know whether you need to spend big bucks on the likes of Jensen or Lundahl transformers to get the "Mojo".

PS. Gyraf make a nice tube mic pre kit and the schematic used to be kicking around online http://www.gyraf.dk/

[Daver]

Steve and Sock,
Thanks for the links. This gives me a lot to work with. I appreciate the help!
Dave

[Amp Kat]

You are right Steve the Input transformer is everything in tube mic pres.
http://www.jensen-transformers.com