Bulding a hybrid Fetzer/Eighteen

[darwin_deathcat]

Hi all,

    I've got an interesting project I'm in the middle of, and I thought I'd post my ideas here to see if anyone has any advice for me during the build. I was looking through the schematics gallery at aronnelson.com the other day, and I came across a schematic of the "Bassman" mod of the classic ROG "Fetzer Valve". Well, I'd tried building this mod (attahed to an lm386 little gem) before just from the text description at the bottom of the Fetzer page at ROG, but had no success at all. Using this schematic, however, I was able to successfully breadboard and then perfboard the design. While I was building it, however, i realized that the Bassman Fetzer could easily be substituted for the first gain stage (including the tone controls) in the Eighteen. (I'll attach links both schems to this post so you can more easily see what I mean)
   So, my idea is to meld the two, right after the "volume" pot (which should be more accurately labelled a "drive" pot). I'm thinking that I will get a very interesting hybrid fender/marshall sound outta this thing that will be killer for Amplified Blues Harmonica (which is what I play). Any ideas?

Bassman Fetzer Schem:
http://www.aronnelson.com/gallery/main.php/v/PenPens-stuff/Bassman_Fetzer.png.html

Eighteen Schem:
http://www.aronnelson.com/gallery/main.php/v/ulysses/ulysses_layouts/ulysses_rog_eighteen/ulysses_almost_eighteen.gif.html?g2_imageViewsIndex=1

[petemoore]

  1 transistor of 1 type = a set of parameters...ie how much gain/distortion/frequency response etc.
  Wide open topic for speculation, a schematic narrows it down from * to x, still a lot of variation in tone can be had from 1 schematic.
  2 transistors of same type as 1 above doesn't necessarily equate to more headroom.
  And increases the possibilities and complexity of the tone and discussion of schematic topic.
  Take a look at Mu configuration.
  Gentle clipping [or even not so gentle] of a succession of transistors can make for interesting dynamics playing because...the dynamic range of the input signal may have more parameters that matter available to it, at more places.
 

[darwin_deathcat]

Hi petemoore,

    I'm glad that you responded to my post. Maybe I am getting confused, but I am not sure what your post actually means. Are you saying that you don't think there will be any way to classify the sound the combined schematic I am proposing to build before I actually build it? If so, then I totally agree with you, I am mainly posting this idea here to see if anyone else has ever attempted something similar, and to get any bits of advice from them before I finish this thing. I am building it as we speak, actually. I have the bassman fetzer up and running and already soldered on perfboard. I'm populating my breadboard with the remaining components from the "right" side of the eighteen schematic, and when I get that done, I'll just chain 'em together to see how it sounds. I'm definately planning to experiment with some of the components, but I think I'll leave all three transisitors alone (that is, leave them to be all j201's). I am definately planning on increasing the value of the decoupling caps from 10nf to at least .1uf for more bass...

[Derringer]

post back a schem and a sound clip if possible

I'm becoming a fan of what jfets are capable of.


going to have to get back to my fetzer concept in a little while

[frank_p]

Look at other topic about Pete's suggestions:
http://www.diystompboxes.com/smfforum/index.php?topic=65878.0

Still have to modify mine...

[darwin_deathcat]

Thanks frank_p
   that thread is certainly helpful. When I get the circuit pinned down, I'll try to draw up what I did in DIY layoutcreator, and post it up here somewhere...