6 (or 8?) DIY preamps post before...

i cant found the thread

Hi guys. I remember that in the past someone of you post about a 6 (or 8?) DIY preamp schematic circuit that worked with multiple input soundcards.
I simply, cant found the thread, and dont remember Who post that.
Someone remembers?

Hmm… BrentG is the guy to ask about that. I know he’s made his own 8 channel preamp for his GadgetLabs 8/24. It was based on a tl074 iirc, and was a bunch of circuits duplicated - although he also added headphone outputs and a few other things, rackmounted.

I’d be interested in that too!!! I wonder how it compares sound wise to a multichannel preamp in the same price range?

I’m also interested.
I have been working on building my own the last few days. The last parts arrive tomorrow, as well as the 1010lt card (yippie).

I tested everything on the breadboard and it works. I have basically been basing it on the mixer project at ESP (http://sound.westhost.com/) and the preamp design on the INA217 datasheet (http://focus.ti.com/docs/prod/folders/print/ina217.html)

I am not electrically gifted, so I have basically been running tons of stuff in SwitcherCad to work it out before slapping it into the breadboard. My goal is to have 4 balanced pre’s and 4 unbalanced pre’s (with modifications to use the DIY wm-61 mic capsules). Each channel will have gain, a clip indicator, -20dB pad switch, and phantom power…well +15V that is. It will not be a true preamp, but my only real goal is to be able to get the signal into the 1010LT soundcard.

hey guys…ill dig those schematics and pics up in a while… but im still here… mua hah ahaaha hhaa :;):

Good! you deserve a mua :wink:

This also makes a nice mic pre - download the data sheet; there’s a schem in there.

Thanks Tempus, i will save it…
im asking for someone in the forum that make himself any schematic, because i dont know nothing about that and will make them with help of a friend… since i need to bother you with questions time to time.

Designing and building a pre-amp that works with audio is very, very simple; an op-amp and a handful of those wee stripy things and a few red or blue lumpy things, and you’re done.

And you can achieve specs that look excellent with little trouble.

However, designing and building an audio pre-amp that sounds as good as you hope for is a whole new fettle of kish!

IMO, the “musical instrument” stretches all the way from the “vibrating element” of the instrument, all the way through to the Hi-Fi speakers and the room the listener is sitting in.

So, I’m looking forward to reading your subjective opinions of this project when it’s finished Marce. :)


OH, you sound like an Sceptic Tank :D
but i have faith, it will help it sound good, Ali :;):

ok guys im having trouble finding my original folder of stuff. ive got one more harddrive to dig thru…


OH, you sound like an Sceptic Tank
but i have faith, it will help it sound good, Ali

Don’t be nasty Marce; I’m never skeptically nor cynical about anything! (Well, apart from life and stuff. :D ).

But audio is strange.

Specifications can look wonderful, be it for an amplifier or a musical instrument.

But how it sounds…Ah! that’s a whole different ball game. (I borrowed that phrase from the Americans on here. I assume it’s something testicular/testosteronical or summat? ???).

Anyway Marce, let me know how you get on.

But if I can offer a few tips; whilst soldering, woollen socks are better than nylon ones, never grab the hot end, and always wipe your tip! :D


Hey Ali! I know what you say about specifications&ears, but you know, it will pre-amplify better than nothing, isnt?
Here is my WHY i want to do this: I have 8 inputs in my card, nice for a little instrumental ensemble tracking, but not enough pres (only four) AND ZERO MONEY (by the moment… well a little large moment)
Is interesting some reactions when you ask for DIY thing, by example, in a local forum (argentina) i ask about the same (hoping that someone post a circuit that with parts easy to get here…) and the answer are “Why you dont buy that mixer” or “why you dont buy than pre”. Well, my answer is "because i dont have money and i enjoy wasting my time doing that things!"

well, if things dont go like i expect, i always can do like the “fox and the grapes”. Good attitude that, isnt? :D

You got it Marce.

Poverty is a great equaliser, and an even greater motivator, which is why I now “rotate” my guitar strings. (Getting that bottom E string tuned up to top E saves money, but it’s a bit of a bugger playing Samba Pa Ti with a banana shaped neck.) :(



which is why I now “rotate” my guitar strings

Oh, That´s innovation…Who need rotary speakers when you have a “Rotary Guitar”?
BTW, have you tryed sometime to tune the strings of your guitar to a diffrent tone and then play any song following your “hand” memory?

yeah, I’ve got this lovely dissonant chord which I call Double E Marce.

I found it when I was tuned to open Emaj, and then fingered a normal Emaj.

So that’d be…hmmmm…E, C#,F#,A,B,E.

So, I suppose that’s a…hmm…E13 no 7 no 3, or summat? ???

Anyway, it sounds good, now all I need is a song to put it in! :D


Anyway, it sounds good, now all I need is a song to put it in!

well, let us know!
I have tryed with my midi keyboard and midiox a “reverse” keyboard, playing well know songs. Interesting… ok, a waste of time, except than some weird but nice harmonyes are able to be used in some new composition.


TravelRec from the kX website has a circuit for a balanced mic preamp at his site, if you scroll down you will see an additional circuit for 48V phantom power.


Electronics->Professional Balanced Mic Preamp

Thanks Doug! Dont thought in the kxproject forum to ask, good idea.

After you get one of this schematic, what more a technician needs to ensamble the thing? the parts are generic or i need to get brand names of it?