Submini Tube Booster Project

[ragtime8922]

Some of you have been asking about the tube projects that I had planned to post. Here is a sub-miniature booster that gives your guitar a very warm touch and a nice boost just before it enters your amp. Therefore it is called the Warm Welcome.

http://tinypic.com/5xobrr


There are 4 more sub-mini tube projects on the way. Another boost with more tonal options, a bluesy overdrive, a high gain overdrive and an amplifier called the Pico Amp (any clue where I got the inspiration for that? :wink: )

I've been working on the amp for a long time because the goal was to be smaller than Zvex Nano Amp yet still have the same tone quality. (Mr. Vex is a true genius. I learn more about that every time I work on the Pico Amp. And Zachary has built hundreds of them!). Anyway, I'm using the small Hammond box, the 1590J or 1590G whichever is the small one, I can't recall and it's downstairs right now. And yes, it will be posted to my brothers here on the forum for a DIY project.

If anyone wants the power supply posted I'll draw one up tomorrow. During testing/R&D I use a tranny, rectifier, filter caps, resistor on a piece of wood for the B+ and a seperate variable DC power supply for the 6.3v heater.

[vanhansen]

That looks interesting.  I'm curious as to the tone it puts out.  Is that 1n cap on the gain pot a treble bleed cap?

[ragtime8922]

That looks interesting.  I'm curious as to the tone it puts out.  Is that 1n cap on the gain pot a treble bleed cap?

Yeah, and I'm still playing with the value. I actually wasn't going to post yet but a few guys asked me so I put a rush on the booster. It's a beautiful warm touch that adds chunk but maintains articulation. You guys have to get set up for tube projects and give it a shot.

[markr04]

Will you post PCB layouts for these projects also?

[Bill Bergman]

OH BOY!!!!!!!!!!!! can't wait.  
I'm about 3/4 done with my mini amp project. I'm pretty sure it's gonna blow up when I plug it in. :shock:  If it does, hopefully yours will be ready to build by then. :lol:

[zachary vex]

you should put the two 6021w triodes in parallel for lower noise if you are using that circuit stand-alone.  8^)

[bwanasonic]

a high gain overdrive and an amplifier called the Pico Amp (any clue where I got the inspiration for that? :wink: )

Isn't that a character from F-Zero?

Kerry M

[lovekraft0]

Other than the obvious novelty of the 6021's size, is there anything inherently audio-enhancing about using it, like really low noise, or a special flavor to its distortion? On paper, it looks to me like a tiny 12AT7 with a somewhat lower plate resistance - what am I missing?  :? Or is everybody just using it because the NanoHead works so well? No offense intended, I just wanted to know if I need to go buy a bunch of 6021s to try.  

[zachary vex]

there's nothing special about it.  nothing at all.  stick to more conventional tubes.  8^)

[puretube]

when I grow up, I want to become a miniature toroidal output-transformer manufacturer...
:wink:

[Melanhead]

If anyone wants the power supply posted I'll draw one up tomorrow. During testing/R&D I use a tranny, rectifier, filter caps, resistor on a piece of wood for the B+ and a seperate variable DC power supply for the 6.3v heater.

That would be cool

[ragtime8922]

you should put the two 6021w triodes in parallel for lower noise if you are using that circuit stand-alone.  8^)

This is just the first part of an overdrive circuit that I thought I'd post as a booster. Also, there is always the phase issue with a single tube stage. How did you mean to parallel both stages? Still take the output from stage 1? Can you direct me to a schematic example?

BTW, there is some extra noise right now due to the fact that I am using a breadboard for the circuit and my gnd and pos bus lines are connected to my FX proto-breadboard because it has the wrapper (in/out jacks, switch, pots).

Zachary, thank you very much.

[ragtime8922]

when I grow up, I want to become a miniature toroidal output-transformer manufacturer...
:wink:

Please grow up now then! That would be awesome :shock:

[ragtime8922]

OH BOY!!!!!!!!!!!! can't wait.  
I'm about 3/4 done with my mini amp project. I'm pretty sure it's gonna blow up when I plug it in. :shock:  If it does, hopefully yours will be ready to build by then. :lol:

Bill, I remember talking with you about that amp but can't remember any details. Is it a starved plate circuit on 12V?

[Bill Bergman]

Ragtime,
No, it's B+ of about 150vdc

[Bill Bergman]

Here's a pic from a couple days ago.  
I'm further a long now but haven't taken any new pictures yet. http://www.freewebs.com/elroy2/16.jpg

hmmm, can't seem to make the link work.

[ragtime8922]

Yeah, the link isn't working. I am really looking forward to seeing it though. Do you have a schem? I talked with you over at AX84, right?

[Bill Bergman]

Yes, it actually just a version of thre High Octane I think by Chris Hurley.
You can cut and paste the link into the adress bar, then the picture should appear.

[ragtime8922]

Bill that is cool. I take it that the blue things are trannys? Where did you get them? (Sorry if I missed a thread or something but I love sub mini stuff so I now have questions...lol)

My power tranny is a torroid from Amveco. I thought I saw the EH trannys and they didn't appear blue, I thought they were like a gold metal look.

Also, what output tube are you using?

I'm using a 5902 in one design and the 6021 in another. 5902 is awesome but getting harder to get and I'm not going to post something that these guys can't build.

I will say this. There is something truly special about running these things single ended. Very nice tone that sorta gets lost with push pull.

[Bill Bergman]

Those are  Amveco 7040's
10VA, 7vac toroidals
I'm using a 5902 for an output tube also. I originally was going to use a 5840 but the mu was too high.