Which booster to overdrive a tube amps clean channel?

[Mann]

I built a Madamp (www.madamp.biz) 15W Marshall copy and it's channel no 1 is clean and I'd like to build a booster to overdrive it.
Any suggestions for a transparent booster?

[delbowski]

i love the simple microamp.  easy to build, no change in tone, loud as anything.

it will boost your volume considerably, but that comes with getting your clean channel to distort.  check it out over at GGG.  that'd be my vote, but i'm sure there's other options as well.

del

[mac]

There are lost of options, treble boosters, signal boosters, etc. Some will distort the clean channel, some will not.
I should experiment with a single transistor circuit like the range master or LPB1, modifying the capacitors to drive your amp the way you like.

mac

[JimRayden]

I built a Madamp (www.madamp.biz) 15W Marshall copy and it's channel no 1 is clean and I'd like to build a booster to overdrive it.
Any suggestions for a transparent booster?

If I may ask, why? What's wrong with the second channel?

----------
Jimbo

[Mark Hammer]

What people call "clean" is very often something that optimizes high end so that wider bandwidth single-coil pickups can sound beautiful through a clean amp and nice sparkly speakers.  Unfortunately, that tends to sound like crap for overdriving amps, the same way wider bandwidth doesn't sound all that hot within overdrive pedals.

Why?

Because what we happily and naively call "distortion" is "harmonic distortion".  Meaning that the harmonic content of what you feed in is misrepresented in the output.  The circuit itself does not "know" what the note is.  It treats a 5th harmonic of a 600hz note as being simply another note, and blindly generates harmonics of that.

In general, what people tend to appreciate as a "productively" altered harmonic content of a note is mostly lower order harmonics.  A big chunk of what people describe as annoyingly "fizzy" distortion is the higher order harmonics.  If your speakers do not have much bandwidth (e.g., big sluggish 12-inchers that roll off above 5khz) then you won't likely hear the fizziness, or much of it, but if the speakers have a little more bandwidth you will.

As a result, what you often want from a booster, or at least with respect to the boosted signal you use to push the amp, is some tempering of the high end.  Indeed, I think one of the reasons why so many have said great things about the various ROG amp simulators comes from the inclusion of a 2-pole lowpass filter ontheir output, intended to mimic speaker restrictions on bandwidth.  That filtering shaves off all those annoying harmonics in the source signal that can result in fizz from the amp.

If I'm aiming for an overdriven sound, I like to constrain high end tightl in earlier stages and gradually spool it out in subsequent stages.  I find that gives greater weighting to the fundamental and lower-order harmonics so that lower order harmonics tend to dominate the eventual overdrive tone from the amp.

That is the VERY long way of saying that whatever booster you settle on ought to have some way of tapering off the highs before feeding that hot signal to an amp channel designed to sound clean, so as to produce lots of low-order harmonics from the amp and not so much of the brittle-sounding higher-order harmonics.

[Mann]

Nothing wrong with the 2nd channel, I just want to test - many of these boosters are simple to solder.
And thank you for the answers.
I actually made a LPB1 (or 2) and a rangemaster (ac128 not leakage measured) some time ago and now I'm testing my amp with different guitars (= different pickups) and just looking for different sounds for different songs.
Even though I firmly believe that the real sound and essence comes from the playing.

[mac]

Even though I firmly believe that the real sound and essence comes from the playing.

I do agree. The best harmonics comes from your heart & fingers.

mac

[Connoisseur of Distortion]

Even though I firmly believe that the real sound and essence comes from the playing.

I do agree. The best harmonics comes from your heart & fingers.

mac

and from the edge of your thumb... 

[Mann]

After hard consideration (and consulting tea leaves...) I decided to support mr. Orman and ordered his mini-booster board.
(A kind of a reward for myself - I just came from a concert where we (choir) performed Beethoven's Christ on Olive Mountain
and now it's time for rock'n'roll...)

[mac]

Even though I firmly believe that the real sound and essence comes from the playing.

I do agree. The best harmonics comes from your heart & fingers.

mac

and from the edge of your thumb... 

... you really are a Connoisseur of Distortion 

mac