Neutrino + ROG may queen

[bangerang101]

 I started building a pedal for a friend who wanted to cop some brian may, deacy amp, cocked wah "style" tones and thought it would be great to make a dual effect pedal (2 effects in one box). So I thought the neutrino might sound good feeding into the runoffgroove may queen circuit (http://www.runoffgroove.com/mayqueen.html). The neutrino for a smooth overdrive sound, then the ROG may queen, for a sort of high gain, treble boost, cocked wah sound for leads or whatever.

So I put them both on my breadboard to test them out together...  w/ the output wire of the neutrino feeding into the input of the may queen on the breadboard (rather than them having there own bypass switch, to be used indivdually...as they would when I actually box it up) I tested them out, and though they sounded good individually, when used together it just oscillates crazy and they don't seem to play nice together... does anyone have any ideas on what I could do to cure this problem? I was thinking maybe some sort of buffer somewhere?... but I'm not sure where at and what values to use, ect... Any help is appreciated, thanks

[bangerang101]

oh... and I was also wondering if anyone knows if these could both be run off of a single 9v dc adapter? If not, could that be the cause of the oscillation?

[dwstanford]

I would try running the boost before the overdrive.  If i understand it correctly, you have the boost running after, correct?  Overdrives can be picky about what you use with them and in what order.  You should be able to run them both off the same power supply.

[bangerang101]

yeah, I tried it before the overdrive but it doesn't get the same tone that it does when it's after it... it has alot less treble, and w/ the overdrive first and the boost last, it reminds me more of a Brian May sound. I just wanna know how I can tone down the gain on the rog may queen, so it doesn't oscillate as easy... but w/ out losing volume. Any ideas for that?

[bigmufffuzzwizz]

You'd have more control if you add a gain control. Try replacing the 2.2k resistor in parallel with 2.2uf cap under Q3 with a 5Kb pot. Lug 1 to GND, Lug 2 to + of 2.2uf cap, and Lug 3 connects to the 220K/Q3 source junction.
Some said it can't be done but this verified layout begs to differ.
http://www.diystompboxes.com/smfforum/index.php?topic=85148.0
http://www.aronnelson.com/gallery/main.php/v/MarkMs-Gallery/album15/album76/May_Queen_LAYOUT.gif.html

Did you try the extra optional cap mod? It says its creates a HPF, maybe something you'd want to put on a switch. 

[bangerang101]

 Alright, cool... I'll give the 5kb gain pot a shot, or at least lower (or raise?) the resistance to a smaller value to get less gain. I did do the capacitor mod thing, but I like the stock value (.0022uf) the best for that. I think when I take it off the breadboard and box it up, it will get a little less noisy as well. Thanks for the help, bigmuffwizz! Really appreciate your help and input.

[bangerang101]

 Yeah, the 2.2k resistor on the ROG may queen circuit controls the gain. I put a 1k there instead and I found more usable for the application I'm using it in (in combination w/ the neutrino). Also, I found that when I physically moved the boards around on the breadboard, the oscillation stopped in certain spots, so I'm thinking it's mostly just an RF interferance type of deal, caused by having it on the breadboard.. So, what I'll probably do is use shielded cable for the inputs, and ground the rf shielding wire to ground on the 3pdt switch. Are there other special ways to keep rf interference to a minimum on these kind of circuits?