What overdrive/distortion pedal that wont change my amp's tone?

[Perkla]

I would say that u build a Marshall Guvnor clone, i have built one and made some mods to it and it have a very wide range when it comes to sound, it fits for both 70´s rock to ..i´d say almost metal and/or hardrock.. this guvnor i built is very good and i really think u should try build one as well.. its also good for doing mods like i did to mine..

[Mike Burgundy]

Okay, Mark, Rick - LOL.
Mark Hammer has the spot for #1 valid point though. Anything you do that changes the harmonic content will alter your sound. I think all suggestions made for certain pedals are very valid - for a certain situation. It works for that person with that gear and that style of playing. So yes, you are probably looking at some serious DIY - basing it on your amps or its cousins structure might be a very  good way to go, but it still may not give you quite what you want. Tinkering is definitely called for, perhaps a totally different solution. This'll be very, very rewarding when you nail it, but it will be a journey. Start out with really figuring out what you want with your amp's tone - A) do you want the clean tone balance to hold up under distortion, or B) do you want the sound of that amp cranked to the hilt but on the same apparent dB level as clean? (or C...) Then figure out what makes that tone (A -okay, retaining apparent tonal balance and relatively light but harmonically rich clipping, so not too much filtering (the "transparant" overdrives might be worth a look here), or B - preamp distortion, power amp distortion, maybe PS sag for some compression, speaker distortion) , and design and/or tinker from there. Try lots of stuff, too. Looking for that sound, keep your ears open - you may very well find unexpected treasures. Happy hunting ;P

[matt239]

I am guessing that your amps "clean" sound is not pristine crystal clear like a big Fender or JC120, but a little crunchy? (I haven't heard your amp..)
You said you've liked clips of Tube Screamers, & MXR Dist+ ?
So you just want a second, more distorted sound, w/o a big jump in volume, or big change in EQ, Right?

If this is the case, you don't need anything terribly complex. Build a Dist+ clone, a TScreamer, or a Marshall Bluesbreaker; all pretty easy.

For mild distortion it's good to cut some bass & treble before your clipping, (especially the bass below 200Hz) this is the main idea in the TScreamer, it has a big mid peak pre-distortion.
With stock values the TS output retains a peak in the mids, but you can easily change the tone control to have a complementary mid scoop, for a pretty flat response overall. (Or a scooped sound if you prefer.)

Check out Jack Orman's articles @ AMZ about TS, & BMP tone controls, & R.G. Keen's "Technology of the TubeScreamer" You can use Duncan's Tone stack calculator to calculate new values.

For even softer more "transparent" drive, try germanium diodes, like 1N34. You may have to use 2 diodes in series to keep the level up where it was with silicon diodes.
For REALLY SOFT drive, try 1n34s with a resistor in series! You can try all kinds of stuff here, & see what you like.

You can even combine the Dist+ & TS style drive, just put some diodes (anti-parallel to ground) after your first op-amp, perhaps on a switch, for two different sounds.

[ozzu2000]

So you just want a second, more distorted sound, w/o a big jump in volume, or big change in EQ, Right?
If this is the case, you don't need anything terribly complex. Build a Dist+ clone, a TScreamer, or a Marshall Bluesbreaker; all pretty easy.

Yeps, thats it

wow, there really is a LOT behind an apparently simple question!
Thanks for all the info

Think I'll try the MI crunch box (http://www.youtube.com/watch?v=pKSiNNYs2jg)
It's just a clipping circuit using 2 leds. Similar to distortion+ I think

[roseblood11]

even closer to the marshall guv'nor / drivemaster. I like the Crunchbox a bit better.

[Ben N]

Take a look at a Timmy. Schematic is out and confirmed by Paul Cochrane, who makes them, or you can get one from Paul for a very reasonable price. Starts out as a nearly clean boost, and you can dial in as much hair as you want for your boost up to medium overdrive, and roll off as much high and low as you need.

[ozzu2000]

Seems very versatile! What does activating the extra diodes do?

[petemoore]

  There's more to distortion than 'pedal'.
   12w can 'soonly' get to distorting if pushing a 12'' speaker a bit. The speaker and the amp have something to 'say' at all times.
  Anything 'pushed' toward or past a 'parameter'...although this kind of jargo is sketchy, in this case 12 tube watt should be easy to make distort...this kind of distortion is different in character than saya 'pushed' Dist+ cleanly amplified.
   Unless playing very low volume, 12w can't go much louder without the 'big change' happening...the output tube load/distort/compress etc.
    Not a whole lot of difference between 12/15...I use 15watt amps and they 'distort' but have a 'volume ceiling' which cannot be exceeded, approaching the 'ceiling' increases the amp distortion no matter what is pushing/boosting the input.
   Another amp is one way to increase 'clean volume' range, all tube amps have their 'window' of volume range where distortion begins, above that volume 'mud' or overdistorting may happen. Low volume tube amp playing [Why?]...the whole reason for the expensive amp is to put it into distortion [might as well use SS for 'clean reproduction'...it's really not much different than using non-distorting output tubes.
   Another way is to put a mic on the amp, but this too is a whole nuther ball 'o wax that offers no guarantee whatsoever that the tone will be the same...it won't...a whole nuther waxball to unravel here too.
    The amp has 'it's' sound level/performance which is regulated or controlled/influenced by the guitar and whatever 'preamp' or dirtboxes chosen to make it 'do it's thing'.
  May not be the thing you wanted to hear...just set the settings and patches so the tone is where it should be, and then figure increasing volume out by...some method that doesn't expect the already distorting output tubes to exceeed their ratings [so to speak].
  A good deal more 'cut through' with limited power/distortion [small tube amp] volume can be achieved by simply reducing the LF's the amp is expected to amp...a lot of current is associated with LF's, cutting the LF's allows the available power to be applied to higher frequencies. Bass demands more power than treble...some 'volume increasing mileage' can be extended to the 'moped' amplifier by using a HP filter...say in the pre-boost or distorter box circuit, if not right at the amp controls.
   All that said, I've used many if not most of the mentioned 9v circuits to push/distort the amp [booster] or 'predistort' [dirtbox]...pretty much any tone except those involving 'big cabinets/big room hugeness' can be had...at volumes where the amp is in it's 'sweet zone'...volume output/ouput tube distortion-wise. The 12w is a scaled version of bigger output amplifiers...does the exact same 'tricks' without killin' the neighbors sensibilities and loosening all the nails holding thier house together.

[Ben N]

If the question was about the diode switch in the Timmy, it is IIRC a symmetric/asymmetric switch, but there have been variations on that, and you could build it without the switch, too.

[SPAZ]

Always thought the marshal blues breaker pedal done this very well. 

[seedlings]

How about a boost pedal, but use it as a cut pedal.  Get your crunchy overdrive set way you like it, then click in the boost pedal, but instead of gaining volume, reduce it for your clean tone.  So withe the boost OFF, you have crunch, and with the boost ON, you have clean.

CHAD