Gus' Overdrive

[petemoore]

  I love the sound, and particularly the way the volume control [especially with my Tele] operates when the Overdrive is on.
  It drives the amp, and it does distort adding just 'edge', but it doesn't exactly fit into what everthing else I've build like called 'overdrive' sounded like [and got bumped for doing so].
  A nice balanced, wide range and of volume, tone, gain control became available at the guitar, the VC became a different tool with this one, it is notably different than any Overdrive circuits I've built [many], there is no heavy distortion, dynamics are accentuated tonally, GuiVolCom gets 'activated', I've become quite fond of this guitar/amp interface, very predictable and I feel comfortable kicking it on when using various tube pre-amps  and amplifiers...can be used of course with FF and other effects OT to this post. 
  Gus had explained the design, this is what intrigued me to build the circuit.
  Thank you Gus Smalley for sharing your knowledge and providing the circuit schematic, it has eclipsed what I had come to believe were reasonable expectations for an Overdrive.
  Plays great on chord / rythms, makes 'lead guitar' tone, it doesn't ever seem to really sound like a guitar through an 'overdrive' [I mean that in the best possible way, every other OD I've built got bumped, I was leary about trying yet another !].
  BTW it's an easy build, and requires only a few values of resistor, I replaced the 100k resistor with a 100k log. as volume control, it stays at 9, 10 is above untiy here, I used a big metal can Si with DMM Hfe reading of ~300Hfe.
     

[Gus]

Thanks for the review.  People who have built it seem to like it.  I am a little surprised more people have not posted about building it.

It is also interesting to find out if people do not like it.

Simple fast build and responds a bit different with different transistors

[Jered]

Simple fast build and responds a bit different with different transistors

  Indeed. 2N4401 and 2N2222A were my favorites, both sounded great. but didn't sound the same. Another quick, great sounding build I think to many people over look is the NPN Boost. Using the MPSA18 or 2N5089, IMHO it is one of the best for pushing the front end of a tube amp.

[DougH]

The overdrive sounds nice and I need to build one at some point. It's very handy, much preferable to a TS or whatever for real amp overdrive.

I still use the NPN Boost too- it's great. Yeah, these circuits should be talked up a lot more than they are. They easily beat a lot of the commercial stuff out there. I guess hand-drawn schematics don't draw much attention compared to fancy graphic layouts and funny names.

[Jered]

  And they even sound pretty good with the guitar volume turned down a bit. To many OD/boost circuits only sound good with the guitar volume all the way up.

[petemoore]

And they even sound pretty good with the guitar volume turned down a bit.
  There's a marked difference what happens when with the GVC related to the circuit sound, that's what sets it apart, the variable tone available at the guitar/picking dynamics responses..that and it seems to wring a tone out of 1 Si Transistor I really like !
  The low parts count of this circuit is able to produce greatly favored results compared to many of my other 9v builds, most started with more components.
  In my case, some of the distortion is created after the circuit [tubes], a very nice compliment to my rig.

[Gus]

http://www.diystompboxes.com/pedals/gusOverdrive.gif


Interesting petemoore likes it with a volume control at the end andjusted for unity if I understand the post correctly.  It was made as a lead type boost that is way no controls(and I wanted to make a overdrive with out any controls).

I think of an overdrive as a circuit made to "push" a tube amp just a bit more.  Not having an output buffer after the lowpass filter at the output makes it sensitive to the loading cause by the circuit after it.  It was made to go into a load of about 1meg like a tube preamp section of an amp.

I think I got the gain and EQ right for 9VDC operation.  That is why you can get the control from the volume control on the guitar.

The EQ caused by the emitter resistors and cap part also effect the bootstrapping of the input a little

[oh7hhi]

Hi!

I built this one a while ago and although it sounds great, I'd like to know what would be best way to add a tone control (treble cut).
How about a 50k pot wired series after output cap and followed by 1nF - 3,3nF cap to ground? Does that series resistance cut too much output?

Thanks!

-OH7HHI

[Caferacernoc]

Sorry to resurect an older thread. What is the input impedence of this circuit? I take it cleans up nicely like a rangemaster when placed first in the pedalboard?