Infinity: an universal guitar preamplifier!

DSV · February 12, 2009, 03:12:47 PM

Hi all!

About 2 months ago, I posted a thread showing how I transformed a BSIAB into an universal guitar preamp for DI applications. Now that I have received all the PCBs and the components, I'd like to share pics the build of a single channel preamplifier for my home studio. Of course, the module presented here can also be used in multi-channel configurations, for live use.

A short presentation can be downloaded here:

http://www.techniguitare.com/projets/ChaosPreamp/infinity_en.pdf
And the schematics of Infinity here:

http://www.techniguitare.com/projets/ChaosPreamp/Preamp-Schems-V1.1-En.pdf

This youtube video shows the first prototype, and contains some samples:

Here!
And here are 2 additional samples (sorry for the sloppy playing):

Vox style

Comfortably Numb (2nd solo) (delay added through Audacity).

I'll add the layouts and the bill of materials later, as I am verifying the printed PCBs through this build.

Finally, here are some photos of:

the prototypes

the current build (beginning)

Stay tuned for updates (as soon as I buy new batteries for my camera

).

PS (a bit of advertising): this poject is born on the french forum, www.techniguitare.com . There are many more interesting project, so visit it

dano12 · February 12, 2009, 03:31:56 PM

Very impressive!

Just finished a quick look at the schematics, looks to be a great build.

petemoore · February 13, 2009, 11:42:01 AM

Big build.
Huge sound in the clip though !

Ice-9 · February 13, 2009, 02:27:28 PM

Thats looking really good, and sounds good also. looking forward to seeing the finished build

DSV · February 13, 2009, 05:07:11 PM

Thanks!

And the finished building is one step nearer ... box is drilled and jumpers are soldered on the main PCB.

Uma Floresta · February 13, 2009, 05:29:24 PM

Wow, nice work!

DSV · February 14, 2009, 10:48:33 AM

Little update: resistors, sockets, capacitors and the trimmer have been soldered on the main board.

Paul Marossy · February 14, 2009, 10:58:12 PM

Looks like a very cool project!

I'm going to do something similar with my ADA Flanger clone, as soon as the PCB arrives...

liddokun · February 14, 2009, 11:10:21 PM

Looks really cool! Good job!

DSV · February 16, 2009, 06:48:39 AM

But now it's getting messy

... offboard wiring!

Paul Marossy · February 16, 2009, 10:37:22 AM

Messy? Say what?!

DSV · February 16, 2009, 02:48:38 PM

I always have the feeling that wires are running over the place, even if they are cut at approximately the right length

. Anyway, I made a test with the jacks and PSU on perfboard, and it works pretty well. I am still waiting for the PCB supports, so I'll have to slow down the construction a bit, but I'll post the layout soon, since it's verified.

DSV · February 17, 2009, 05:17:29 PM

Here is the PCB:
http://www.techniguitare.com/projets/ChaosPreamp/guitar_preamp.pdf
And here is the parts layout:

Enjoy

DSV · February 21, 2009, 08:24:23 AM

Finished!

Here are the last photos ...

Enjoy!!!

DSV · February 23, 2009, 06:16:53 PM

Here is a .zip file with all the photos:
http://www.techniguitare.com/projets/ChaosPreamp/infinity_photos.zip

And, about the transistor biasing, Q5 in the common source stage is biased at 6V.

I'll post the values of Vth and Idss for the transistors as soon as I find the sheet where I wrote them.

Paul Marossy · February 23, 2009, 06:43:43 PM

Quote from: DSV on February 16, 2009, 02:48:38 PM
I always have the feeling that wires are running over the place, even if they are cut at approximately the right length . Anyway, I made a test with the jacks and PSU on perfboard, and it works pretty well. I am still waiting for the PCB supports, so I'll have to slow down the construction a bit, but I'll post the layout soon, since it's verified.

Yeah, I know what you mean. But your wiring is far from messy.

DSV · March 06, 2009, 04:27:09 PM

Thanks, Paul

(I had completely missed your reply)

And here are some new clips. After listening to them again, here are my impressions:

Two minutes to 2h in the morning: Iron Maiden style. Probably thin. I scooped the mids on this one
Plexi style!: maybe a tad too fizzy
Thunderstruck: instrument placement ain't that good, nor is playing
Sharp dressed man: difficult to capture the ZZ-Top tone, I tried to do my best ...

Enjoy!

petemoore · March 06, 2009, 08:47:55 PM

Not to disagree but I disagree, these aren't
thin, The IM was really full of fine 'big guitar' sound !
Plexi style!: fizzy, nope, this one has really cool playing and the mix is a fine example of your wizardry applied !
Thunderstruck: instrument placement ain't that good, nor is playing
Rythms sound really nice thick and grindy, the leads maybe could have used a bit more 'push'.
Sharp dressed man: difficult to capture the ZZ-Top tone, I tried to do my best
Ok you got me on this one. Try playing it through the plexi-style or IM settings, or the rythm tone for the T-struck...they're outstanding, Impressive !

tednet · March 07, 2009, 06:58:09 AM

pure awesome

also, if it's not too much trouble, could you post the parts list

punkin · March 07, 2009, 03:09:04 PM

Wow! Cool...BUMP!

That's at the top of my list of "must-build" list. I'm thinking a 1 RU rack unit enclosure with a rotary/switchable tone stack and an effects loop.

News:

Infinity: an universal guitar preamplifier!