Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Effects => Topic started by: jojokeo on December 09, 2012, 11:51:44 pm
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While I've been on a bit of a Trainwreck & Marshall kick drawing up schematics for my next build, I finally put this pedal together. It's been ready to go for several months but I've had other priorities lately. Anyway, it's similar to a Box of Rock using mosfets w/ an independant boost, etc. and emulates a cranked JTM 45 even w/ a tiny bit of sag w/ the drive all the way up. It has sweet transparent tone w/ the drive down below noon and even order harmonics out the wahzooski past high noon w/ great controlled feedback at a modest volume as it sustains very well too. It's great fun to play and will be on my board soon w/ it's brothers and sisters after I figure out where it will fit-in best.
I'd like to share some of the steps of my building process with you here. I use a program for the layout similar to jschem, use vero board (love this stuff) and make cuts where necessary. No etching & drilling! Gather parts and assemble the board. Then wire up the pots, jacks, and switches - just the bare bones for now to test, tweak, & adjust if necessary. Also to make sure it sounds and plays well enough to be worthy of proceeding forward.
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One of the ways mosfets and jfets get their tube-sounding qualities and similarities is by the way they smoothly clip the signal and keep the leading and/or trailing edges rounded off the way tubes' gently clip the signal. I use Inkscape which is a scaleable vector graphics program for the design and placement of everything. Using laserjet waterslide decal paper makes things easy to apply. One of the main differences between Inkscape/svg files rather than a bitmap-based program is that you can scale things up or down easily w/out pixillation issues. I print out a paper copy also to tape to the box so that I can place it where wanted, center punch all the holes to get an exact fit for the decal and then drill everything out. Cutout the decal, soak, apply, position, remove any bubbles, wait to dry, then apply a few coats of clear spray from a can to protect the decal and it's time for final assembly.
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Very cool Buddy,...the graphics look perfect,,,,love the Jimi pic.....
I tried the laserjet thing because of one of your earlier posts and it does work great, when you take your time......where do you get your paper?
I'm gonna have to try that Inkscape program,because it took me forever to scale in Paint :BangHead:
Your description of the sound really makes me want to plug one in...I think there are a ton of guys out there who are looking for those qualities in an OD
One of the ways mosfets and jfets get their tube-sounding qualities and similarities is by the way they smoothly clip the signal and keep the leading and/or trailing edges rounded off the way tubes' gently clip the signal.
Thanks for that explanation,,,,because we hear so many claims "tube sounding this,,,tube response that"....it's nice to have a small understanding of WHY
The more I try to build my OD sound into an amp the more I start to question and consider the use of this stuff hard wired into my tube amp,,,,as we have discussed....
Anyway,,,,GREAT JOB!!.....it's really cool to be able to sit here in Phila. and share in what you're doing out there.....Thanks for sharing! :thumbsup:
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Nice clean work. You should be pleased.
Can you round out the topic with the schematic and bill of materials? I'd love to build one of these one day.
Thanks!
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I did my own thing but here's all the info that you need or could want if you want to build your own Box or something close. I like your site simon. It's got the SHO for the boost which you elected not to build in going w/ LPB-1. Could be a nice addition?
http://www.freestompboxes.org/viewtopic.php?f=7&t=37&hilit=box+of+rock (http://www.freestompboxes.org/viewtopic.php?f=7&t=37&hilit=box+of+rock)
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I did my own thing but here's all the info that you need or could want if you want to build your own Box or something close. I like your site simon. It's got the SHO for the boost which you elected not to build in going w/ LPB-1. Could be a nice addition?
http://www.freestompboxes.org/viewtopic.php?f=7&t=37&hilit=box+of+rock (http://www.freestompboxes.org/viewtopic.php?f=7&t=37&hilit=box+of+rock)
Thanks Jojokeo.
I built the LPB-1 too; destined to be the boost stage of a tubescreamer (with asym diodes). One day I'll get around to finishing that project. My SHO build and the LPB-1 were exercises to see if I could create my own veroboard layout from a schematic, so as such they were a lot of fun.
Thanks for the link...this one's definitely going on the list for the near future!
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I think you'd like it? It's basically cascaded mosfets/cascaded SHOs or "mulitple hard-ons" :huh: There's more than enough gain on this one too, but it can drive or be driven by other pedals w/out an issue (except fuzzies). One my favorite "tricks for tone" especially in a live gig or show environment is to use a treble booster before an overdrive pedal fed into a tube input stage/amp - now that's a Super Hard-On and sure to please!!!
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I have plenty of (too many) overdrive pedals, but none based on an amp topology. So trying it does appeal to me.
I like my SHO at the end of my chain so I can use it for "more" whenever I want. Sound guys hate it because these days it seems they want control over volume during a solo. So when I stomp on it I can see the frown from the stage ;) I've used it on the end of a ton of pedals, or just on its own...it works beautifully. Even keeping it on all the time adds some life to dull sounding tube amps.
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Even keeping it on all the time adds some life to dull sounding tube amps.
Geeze, I hope nobody that's on this site has got that problem? If so, maybe they should do something else!? Or find somebody here that lives close by to hook 'em up. Life's too short to have a dull sounding tube amp.
Seriously, I know what you mean. If it's not old and worn out tubes, it's usually just low gain and needs a signal strength jolt into that V1 position to liven things up.
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Way way back, in a galaxy far far away.... I used to use two piggybacked LPB-1's into the front end of my Bandmaster and later my Marshall 50 watters. Lots of glorious noise and feedback! Then I replaced them with a treble booster and a sustain unit from PAIA that I built - much lower noise floor! I need to see if I can dig up some old pics of that mess!
Jim
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There's a bunch out there but here's a few to get started with:
http://www.freestompboxes.org/ (http://www.freestompboxes.org/)
http://www.diystompboxes.com/smfforum/index.php (http://www.diystompboxes.com/smfforum/index.php)
http://www.guitarpcb.com/ (http://www.guitarpcb.com/)