String Definition

[mcasey1]

I just breadboarded Gus Smalley's GCS Overdrive and compared it to my DOD 250+ (1977 version).  One thing I noticed right away when switching between the two was that the 250 had much better string definition or clarity than the GCS.  However, I like the smoother nature of the overdrive in the GCS circuit much more.  What factors influence string definition (in/out caps, clipping section...) and/or what could I do to bring some more clarity to the GCS drive?  I apologize if it is a stupid question, but it is only my 2nd breadboarded circuit and I'm trying to incorporate both experimenting and research.

Thanks!
Matt

[GibsonGM]

Hi Matt,

Why don't you post links to both schematics so people can take a look and chime in?
There are a lot of factors at work there.  Definitely tone shaping has a lot to do with it (read the FAQ, mods...) - how much of the signal is kept 'intact' before amp./clipping and all of that, and what you 'bring back' at the output.  There are trade-offs.  Soft clipping vs. hard clipping...diodes in the feedback loop as opposed to on the output will keep more of the 'guitar tone'. The filter section in a feedback loop does a lot, too.

Specifically on the GCS, I'd play with the input/output cap values...try increasing C1, decreasing C4.  R7 & C5 are a lowpass filter, play with the cap value there.  The fact that it uses a BJT may limit the frequency response of the circuit, too, making it have less "sparkle"....

[DougH]

What we need is a definition of string definition.

[John Lyons]

I'd say string definition = a clear representation of each string and picking dynamic retained through the gain applied....

The input cap dictates the definition is a simple circuit like this. Basically limiting the amount of bass that gets through the circuit.
Too much bass and the definition of the lower strings gets sloppy. This also has a big effect on the amount of drive the circuit has though so it's a balancing act between definition and fullness.

The .1uf  input cap is letting most frequencies pass so try .047 and see what you think.

john

[David]

I'd say string definition = a clear representation of each string and picking dynamic retained through the gain applied....

So in keeping with this description, two examples of loss of definition would be "Hello, I Love You" and "Incense and Peppermints".

[John Lyons]

Yes and no. While the kinks song is distorted it still has a fast attack and the dynamics are snappy which would lend itself to my description of definition...each string is defined and rings out without being overmodulated. Think of an acoustic guitaror clean bright electric and how the strings react to fast picking, and how the string of a full chord respond to pick attack and strumming.
A well staged distortion or overdrive will keep these characteristics. This goes along with how the tube screamer is set up.
The bass is restricted in the input and clipping so the lower frequencies do not overpower the clipping. Then the treble is bled to ground after the clipping stage so the circuit isn't overly bright. Pick attack is retained and although there is a mid hump it sounds articulate and defined.
Blah balh balh....

I can hum the Incense and peppermints tune but can't think of the guitar work...I think it's pretty fuzz and squishy compressed though..which would be not defined as the sound is blured and attack is slow...   Ah these terms again....

john

[nosamiam]

This Youtube vid of a mod to the Orange Tiny terror has before and afters. IIRC, the "after" has quite a bit better string definition than the before.

**oops: http://www.youtube.com/watch?v=gpzwU5QfV4w (forgot to add link)

[Joe Hart]

What YouTube video?
-Joe Hart

[Joe Hart]

Thank you! I have been thinking about picking a Tiny Terror up. It sounds cool! I wonder what mods he did??
-Joe Hart

[mcasey1]

GCS:  http://www.geocities.com/j4_student/gusOverdrive.gif

'77 250:  http://www.aronnelson.com/gallery/main.php/v/MarkMs-Gallery/album15/album76/1977_OD_250_LAYOUT.png.html

The input cap in the DOD is .01uf and the GCS is .1uf.  Quite a significant difference.  I'll fiddle around with it some more to see if I can clear it up a bit.  Thanks for the help!

Matt

[DougH]

That's what I would try first.

[nosamiam]

Thank you! I have been thinking about picking a Tiny Terror up. It sounds cool! I wonder what mods he did??
-Joe Hart

He discusses it very briefly and vaguely in the comments on the video page. He naturally doesn't say much, but you can get some idea. Maybe if you slow the modding section of the video down and have really good knowledge of tube amp theory you can figure it out.