Microphone Preamp

[basstard]

Hi gentlemen, I've been asked by a friend if I can build him a mic preamp and I'm looking for some projects/schematics but can't really find anything that suits the requirements [not that they are high at all].

It must have:
-a decent freq response [the flatter the better]
- +48v phantom power for condenser mics
-not so expensive building costs

and that's pretty much it. it doesn't even have to have tubes in it necessarily.

I made a lot of search both on google and here but only found expensive kits or stuff without +48v,,,

Anyone can point me in the right direction please?
[btw, altho I built a few tube guitar amps, I'm a complete newbie at mic preamps]

[Gordy]

Maybe this one?

Gyraf Audio - G9 DIY

[basstard]

Yes, this could do! looks kinda sophisticated but on paper it seems to have it all,,, thx mate!

If anybody has other suggestions then keep'em comin'!

[bill_a]

Have you looked at the Jensen Transformer website?

WELCOME TO JENSEN TRANSFORMERS, INC.

They kinda-sorta wrote the book on mic preamps. Lots of examples and spec circuits...
Bill

[88man]

I've heard that the Hamptone, Gyraf G9 are also good kits.
If you want a Op-amp based preamp, here is another good build - the AS083 on the page:

JENSEN TRANSFORMERS, INC. - APPLICATION SCHEMATICS

Here is one I am considering building from the Jenson Transformers site. It's 3 circuits on the site that I merged together. I started a thread last week on this:

Cascode Tube Mic Preamp: 12AX7/12AU7 Schematic

I may rework the circuit to accept a 12AT7 or 6922 in first stage.

[nigelwright7557]

Originally Posted by basstard

Hi gentlemen, I've been asked by a friend if I can build him a mic preamp and I'm looking for some projects/schematics but can't really find anything that suits the requirements [not that they are high at all].

Its probably cheapest to buy a second hand preamp off ebay.

[Bamalama]

It doesn't really take that much to make a good-sounding tube mic preamp.

I can't scan but I can mail. If you pm me an address I'll look for the drawings I made for mine -- but it's just a 12ax7 and a 6sn7; you could probably figure it out just as well. I did have access to a pretty nice regulated power supply, so I might be considered to have cheated a little.

B

[basstard]

Jensen schematics look good but transformers bring up the price. This guy wants to start cheap and then, possibly, step up gradually.

88Man, that AS083 seems a bit complicated because of layout issues [as stated in the pdf]. Your project seems quite interesting shame the output transformer is listed at $137! [btw, search facility doesn't like 3 or less letter words so your thread didn't come up when I searched for 'mic preamp' - shame]

Bamalama, I pm'd you my email address but re-reading your message I guess you meant my physical home address, didn't you?

I have seen also this Bizzar Green Pre: Green Mic Pre and
DIY Factory - green mic-pre

Any opinions about it? I'm not a "if it doesn't cost a thousand bucks then it'll sound sh**" guy,,,

[Bamalama]

Hey, B, I just emailed you a couple amateurish drawings.

You have to go for the Jensen. For the hours you're going to spend putting all this together, building a power supply, getting the tubes...the input transformer is almost the least of it.

Tell your friend that you're going to give him something real. And of course, have fun doing it...!

B

[bill_a]

What 'Bama said... !
Bill