Anyone remembers the MINITUBES preamp?

dschwartz · March 16, 2007, 09:17:47 PM

At my first steps as an effect diyer, y came across a very nice project called the minitubes preamp.. it hat j201 fets and two channels with independant EQ...

I live in Santiago, Chile, and i was boomed to discover that there were no fets to use, smallbear was years light ahead of me and i only got some shitty replacements (k103, i think)..and never found the voltage pump.....of course, 6 years ago y knew nothing about circuits and twaking, so i made the board and let it rot.....

anyone else was interested inm this project?? did anybody build it?.....how was it? ...

maybe now that i´m more experienced i could give it a try, but i want to be sure it is whorth the effort...

thanks!!

alextheian-alex · March 16, 2007, 09:48:07 PM

RG has a layout and board. http://www.geofex.com/Article_Folders/minitub.htm it sounds similar to the booster 2.5 apparently

dschwartz · March 17, 2007, 12:20:07 AM

yep, that was the layout that i used for the board...
but, how did it sound..say....compared to dr boogey or..more actual designs?

will it work with 9 v? or 12?

aron · March 17, 2007, 01:49:24 PM

It was darn good and I still have the earlier prototype designed by Jack Orman. TONS of gain, and BTW read this and remember this, it was the FIRST complete DIY published amp type circuit using JFETs, full on amp tone stack values, etc....

Yes, it all points to this schematic. Everything else like this came from this design. When it was released BIG lightbulbs went off I tell you!

Thank you Jack Orman!

http://muzique.com/

MartyMart · March 17, 2007, 01:55:17 PM

Oh yes, I built a Booster 2.5 not so long ago and it KICKS BUTT !!!!

Great project and as aron said, thefirst of many !

MM.

dschwartz · October 27, 2008, 09:15:27 AM

i know this is an old post..but, do someone have the minitubes II schem?

DougH · October 27, 2008, 10:18:42 AM

I breadboarded it and it sounded great. But you need to run it a 36 (or was it 40?) volts to get reasonable headroom.

Schematic should be on Jack's site somewhere. In a nutshell, the marshall side is a typical 2203/2204 master volume preamp done with miniboosters and the fender side is a blackface preamp implemented similarly.

dschwartz · October 27, 2008, 10:49:58 AM

i´ve searched a lot on amz, and no minitubes schem available...

DougH · October 27, 2008, 10:53:34 AM

You may have to buy his cd to get it.

dschwartz · October 27, 2008, 11:20:24 AM

it look like it´s that way..

well, i´ll better stick with my own ideas

Mark Hammer · October 27, 2008, 11:39:02 AM

I think I may have snagged a copy of it from before there was a CD. If memory serves (and it will have to, because the file is at home and I'm at work), the MT-II was essentially a two-channel affair with two different tonestacks. Never built it, but it seemed nicely tailored to be the front end of a small practice amp.

Given that I don't have the aforementioned CD, I have no idea if it is appropriate to offer the file or not (assuming I have it). Some guidance here would be good.

dschwartz · October 27, 2008, 12:07:42 PM

well, nevermind..
i´m planning to design a 2 channel fet preamp, well, hybrid preamp (opamps and fets), i was just wondering how the switching was on the minitubes..

i´d like to use a sequential switching to change from OD to Clean to bypass..Handy Dandy little circuits have a nice 4017/4066 sequential switch that may be useful..

DougH · October 27, 2008, 12:19:01 PM

I think he just used a simple stompswitch from what I remember, Daniel. I believe it was a scheme where it would ground the input of the unused channel. That part of the circuit had a little bit of a "trick" to it from what I recall.

dschwartz · October 27, 2008, 12:24:52 PM

at least on the pcb layout on Keen´s page, it looks like the channel switching is fet-driven...

Bucksears · October 27, 2008, 02:43:19 PM

I built one years ago (4yrs+), along with Doug's original VoxEXP. The eq on the MT was very subtle, but it had a thick (albeit compressed) crunch.
That one might be a good circuit to revisit and improve upon. It (and its predecessor, the FET Muff) certainly changed the game in terms of how distortion circuits could sound.
Of course, Jack's Miniboosters in the MiniTubes led to the BSIAB, and later (my favorite stompbox) the BSIAB II.

amz-fx · October 28, 2008, 07:45:47 AM

Quote from: Mark Hammer on October 27, 2008, 11:39:02 AM
Given that I don't have the aforementioned CD, I have no idea if it is appropriate to offer the file or not (assuming I have it). Some guidance here would be good.

If anyone is serious about building the pedal and doesn't have the cd (or want to buy it) then just send me an email and I'll send you the schematic to help you out.

Serious inquiries only as I'm packing in preparation for a move.

Best regards, Jack

Mark Hammer · October 28, 2008, 07:49:53 AM

Quote from: amz-fx on October 28, 2008, 07:45:47 AMSerious inquiries only as I'm packing in preparation for a move. Best regards, Jack

Without wishing to pry, is this move a hurricane-related decision? I know you've had more than your fair share of such "inconveniences" in recent years. Either way, good luck with the move. Been through too many myself, and I swear I'm still stumbling onto unpacked boxes from 3 moves ago. Take it from a "pro": LABEL EVERYTHING!

DougH · October 28, 2008, 07:51:08 AM

Oh wow, Jack. Did you just ask for a lot of email.

Dragonfly · October 28, 2008, 09:35:03 AM

Quote from: amz-fx on October 28, 2008, 07:45:47 AM
......I'm packing in preparation for a move.

Best regards, Jack

Best wishes for a smooth and minimal hassle move !

Having just moved in August I can sympathize !

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Anyone remembers the MINITUBES preamp?