New Guy w/Questions/requests (of course)

[tdkask]

My son recently started learning guitar (I have no clue whatsoever musically) and wants a distortion box. I, however, am an electronics guy buy trade and love to tinker, so decided we could build one. A lot of searching online has lead me to realize I don't know where to start. Basically, I'd like to build a low voltage 12ax7 based tube or hybrid distortion pedal. I have found a few schematics like the VT911, Ron Black (but with 12AX7), etc. I'd appreciate any suggestions. I'd prefer a tube pedal over all SS just to let him have a tube to look at.

For a note, I already have:
variety of Caps, resistors, etc
5ea 12AX7 tubes
12VDC wall PSU
variety of pots, etc
PCB etch capability (DIY toner transfer style)
soldering capability, etc

would benefit from:
OP-AMPs/transistors available at RadioShack, or substitutions thereto
obviously PCB layout would be convenient, but I don't mind.

Thanks for any suggestions for this DIY'er and his eager 16yo

tdkask
St. Marys, GA, USA

[LucifersTrip]

I haven't built this but have it bookmarked for a future project:

[tdkask]

Is one of the ones I looked at. Gotta find a 4558 sub at RS... lol

Will a TLO82 work, and anyone know off-hand if it is pin for pin?

[Quackzed]

yep tl072 tl082 pin for pin...

[tdkask]

It seems very similar to the VT911 except a couple OPAMPs cut out. Any real difference in that?  think I'll start collecting parts.

[Quackzed]

yeah, looks like behringer cloned it with a buffered vref... i think you can still get tl074's at RS if you wanted the buffered vref...
there may be a layout or 2 on 'the net'...brb...
theres a project over at general guitar gadgets with a layout... info etc...
http://www.generalguitargadgets.com/projects/17-distortion/83-tube-driver-project

heres a perf layout, i think its the same...

[tdkask]

Thanks. That's good info. Don't find TL074s, though... just TL082s. RS sucks these days, and for prototyping it's no fun to order from 'net. Not a lot else for me without a 1+ hour drive.

I like the portability of the above for 9V battery operation if desired. Will it also perform as well/better off of 12V?

(EDIT: I see the one on that project is 12v. Sorry)

How does it compare to the B K Butler, BTW?

[reveal]

Arron's Shaka tube [on this site http://www.diystompboxes.com/smfforum/index.php?topic=18369.0] uses a 12 volt PSU and there is some discussion available.  [Rectify the power going to the heaters.]

Also  http://www.dogstar.dantimax.dk/tubestuf/mctube2.pdf      It appears more along the lines of the tube drivers available commercially due to the higher voltage.  Also a little more dangerous.    Here it is in project format with a board layout from "tonepad" http://www.tonepad.com/getFile.asp?id=43

This one just uses 9 volts and is "pure" tube.  http://beavisaudio.com/bboard/projects/ttb_Valvecaster.pdf

   You might want to start with something simple like a silicon fuzz or the beginner project on this sight.  Guitar effects , especially distortions and fuzzes, defy some of the common sense found in most electronics.  Plus you might put a lot of time into it and wind up with something that isn't the "sound" he is looking for.  Ask him if he has an idea what he wants and clone it.  The resources online are endless.  

   BUT if you like to tinker you couldn't have picked a better area for an electronics guy.  For a relatively small investment in parts you can build all kind of things.  From my observations the projects on beavis audio require the most readily available parts.  There is a lot of hype surrounding vintage parts, and in some instances (like germanium transistors or Craig Andersons Tube driver) it's applicable.  
    Have fun,

[tdkask]

Arron's Shaka tube [on this site http://www.diystompboxes.com/smfforum/index.php?topic=18369.0] uses a 12 volt PSU and there is some discussion available.  [Rectify the power going to the heaters.]

The Shaka looks good. I hadn't found a schematic until now that wasn't the drawn one... hurts my head... lol

Also  http://www.dogstar.dantimax.dk/tubestuf/mctube2.pdf      It appears more along the lines of the tube drivers available commercially due to the higher voltage.  Also a little more dangerous.    Here it is in project format with a board layout from "tonepad" http://www.tonepad.com/getFile.asp?id=43

Not opposed to this, but my 16yo is likely more safe without the 160V B+

This one just uses 9 volts and is "pure" tube.  http://beavisaudio.com/bboard/projects/ttb_Valvecaster.pdf

Like it, but not hoping to recalculate for the 12AX7s I have already or buy more tubes right now.

You might want to start with something simple like a silicon fuzz or the beginner project on this sight.  Guitar effects , especially distortions and fuzzes, defy some of the common sense found in most electronics.  Plus you might put a lot of time into it and wind up with something that isn't the "sound" he is looking for.  Ask him if he has an idea what he wants and clone it.  The resources online are endless.

Good advice, I know, but also a good excuse for me to tinker and draw him into a electronics project and build his own box.

BUT if you like to tinker you couldn't have picked a better area for an electronics guy.  For a relatively small investment in parts you can build all kind of things.  From my observations the projects on beavis audio require the most readily available parts.  There is a lot of hype surrounding vintage parts, and in some instances (like germanium transistors or Craig Andersons Tube driver) it's applicable. 
     Have fun,

I have reworked (not exactly "restored") antique radios (1930's to 1970's) before and built a clone Alembic F2-B for a friend once, so will get there. Also, I will prototype everything before the "real box".

Ultimately it will be in an old sewing machine foot pedal with the switch activated by pedal. Looking forward to the build.

[Jdansti]

Welcome!

If you do have to order online, here are a few places that a lot of us use.

http://www.mouser.com/home.aspx

http://www.taydaelectronics.com/

http://www.diystompboxes.com/zencart/ (Aaron's store here at diystompboxes-very reasonable shipping costs)



BTW, since you're an electronics guy, your knowledge would be appreciated here on the forum.  We all need help at some point.

[Quackzed]

Ultimately it will be in an old sewing machine foot pedal with the switch activated by pedal. Looking forward to the build.

Report 

i'd scrap the sewing machine pedal idea...
it's not a bad idea to use things you have for someting, recycle and all, but it's alot of work invested and in the end a 6-8$ hammond box will be easier to paint / stylize, be more robust and sturdy, and last but not least it will look 'professional'... check out the pictures thread for some inspiration...once you see some of the tube project pictures, you might have a better idea of what you want it to look like...

[jk-fm]

Use the sewing machine pedal for a quick-n-dirty op-amp based distortion - just an amplifier with a couple clipping diodes on the output, like the Boss DS or the Proco Rat

http://www.generalguitargadgets.com/richardo/distortion/index.html

Save the tubes for something nice-looking like this http://www.diystompboxes.com/smfforum/index.php?topic=36392.msg858922#msg858922

Also, won't tubes eat a 9v battery in minutes?

[Jdansti]

Electrical boxes from the hardware store are great for a rugged inexpensive pedal enclosure.  I utilize the knockouts and large washers for the jacks.  You could use a duplex box if you need more room.

[Quackzed]

that knockout/ large washer idea is great!, ive used raco boxes before but drilling em was a pita...

[tdkask]

Decided on the Real McTube, basically.

Went with the schematic below for simplicity, except used a 1M for gain (still just a voltage divider, right?) potentiometer, and 660K between Pin-6 and B+ (had two 330K sitting around... threw them in series).


(Above schematic found here, linked from youtube post.)

My PSU is a wall adapter (12VAC) plugged in to jack in side, then a small 10:1 transformer from a 80's clock radio, in reverse. There is surprisingly very little hum on the audio with a AC filament voltage, thought it is a little high at 14.5VAC (will put inline resistor later?) For B+, a rectifier block and a pi filter (2x47uF and 100Mohm) gives me just barely over 160VDC. All of it fits nicely inside the sewing machine pedal, but with the tube mounted on top. (pics ASAP). It is point-to-point wiring, and works great, even if not beautiful.

One questions, though... to get more overdrive (no real difference in first half of drive pot) where should I tweak? Would lowering my biasing resistor at Pin-3 give more distortion? Or do I have it backwards? Second stage is mostly just amplification, right, with distortion in first stage?

Thanks. Great build. Pics to follow soon in present state, and later in fresh paint, under-lit tube, etc.

[tdkask]

Just wanted to update with pics of pedal (still needs to be disassembled and repainted, and DPDT switch replaced with push type) Also need to build a "cage" around tube to protect it some.

Changed resistor at Pin-3 to 4K7 to get full range in overdrive, and had to change my volume to a 25k in series after a 400K (IIRC) just to get a small enough sample to not overdrive his Orange Crush 35LDX SS amp. There was probably a better way (maybe reduce second stage gain?) but it was what we had on hand and worked for us. Sounds real good and he loves it and is very proud.

Thanks for the help and info here. I'm content with my first build. Next will be a SS, maybe a phaser.

(click images for larger view)


   

[Jdansti]

Excellent!!!  I'll be watching for a sewing machine controller at the local Goodwill store!

The single triode preamps are really nice, but won't give you a tremendous amount of gain. One thing you could do, although the purists don't like it, would be to use a simple diode clipping circuit to get some additional distortion. You'll have to play with different types of diodes and LEDs to find what sounds best. Here are some examples. You'd want to place these circuits just infront of the output pot in your schematic.  Alternately, the clipper circuit could be placed Ina separate box after the McTube.

http://www.muzique.com/lab/warp.htm

[mshuptar]

That sewing machine footpedal enclosure is rad! IMO, you don't even need to paint it - it's got that sort of "steam-punk" vibe.

[tdkask]

It worked out pretty well. I don't think I could have fit a whole lot more in there, maybe, though. I have had it for years. I bought it thinking it'd be a controller for a Dremel or something, but just never used it. Then I ran across it in recent weeks, so when this project began I remembered it and decided it'd be cool. We may not paint it... does look pretty cool. I had a 64 Fairlane the same color. Does need some sort of tube protection, though.

[Quackzed]

that did come out really cool looking...
o.k. i take back my advise to buy a new box, that thing looks cool ,like retro futuristic...