Trouble wiring up Si/Ge DPDT switch in npn rangemaster build

[Bandwagonesque]

Hi folks. I wired up a daughter board in my NPN rangemaster build to switch between a silicon and germanium transistor and i'm having more trouble than I thought I would have considering i've had success wiring things up the same way with a DPDT before on a fuzz face.

Here is a look at the daughter board and what the layout is based on as seen here http://guitarpedalbuilders.blogspot.com/p/blog-page_66.html
(I left out the rest of the layout on the daughter board layout to save time, the rest is basically the attached npn rangemaster schematic):






What my problem is, is that it seems that I can't get both transistors to work at the same time, errr...what I mean is that while say the Si side is switched on, it won't work unless I pull the germanium transistor out on play, and vice versa. I can't have both transistors in at the same time basically.

As of right now i've been able to remedy the situation with a 3PDT and it works great just as I want. But I need to use a DPDT in this instance and can't figure out why its giving me trouble on the rangemaster. I've had the problem on my breadboard and my main build with completely different types of DPDT switches (all the ON/ON type) and sets of transistors (with the same pinouts). I've checked my pin outs more than I care to admit so I really don't think its that. I have the DPDT board mounted on the daughter board horizontally but have that taken into account with the layout so don't think its that. I have the 3.9K resistor replaced with a 5K bias trimmer for each transistor but think my routing is all well and good. So really kind of clueless if this can even work or not. Can anyone tell me if i'm overlooking anything in regards to theory or doing anything wrong with my layout? Am I needing to use a different pin out with a rangemaster circuit over a fuzz face (for example, the emitter's are connected and not going to the switch instead of the Base's as they are now)? Any help would be greatttly appreciated as this is the final step in closing the book on this range master build. If I have to use a 3PDT so be it but would really really like to use up this car boot stash of DPDT's I have instead. Thanks a bunch folks for reading and have a nice weekend

[mozz]

You should be able to switch just 2 leads and have it work. Hate vero.

[idy]

You *should* be able to dpdt...but unlikely to like the results. The biasing needs of Ge and Si are different enough that the smart money is on building two separate boosters and swtitching them. The first idea has been eliminated from polite conversation, the second is a handy thing to have for utility and education.

it may have "worked" in a fuzz because brute force.

[idy]

Last time it came up:

https://www.diystompboxes.com/smfforum/index.php?topic=127548.msg1223720#msg1223720

[iainpunk]

You *should* be able to dpdt...but unlikely to like the results. The biasing needs of Ge and Si are different enough that the smart money is on building two separate boosters and swtitching them.

i second this idea, but with a mix pot.

also, if you slightly misbias the Ge stage so it clips a bit, (as it were in the OG rangemaster), and ''properly'' bias the Si, it gives a cool 'two ends of the spectrum' vibe from ultra clean Si and even to raunchy Ge

cheers

[mozz]

If it's a bias problem, just have emitters both with different resistors, or have one collector fixed and the other with a resistor added. 

[idy]

Input impedance is also different for Si and Ge. The low input Z of the Rangemaster is part or its "charm." Change the transistor and that changes also. And so the frequency range of the input cap (which cuts the bass) won't be the same either.

[mac]

Use a very low gain silicon like 2n2369, TIPs, etc, anything in the range hfe: 60-90.
Input impedance is hfe*26mV/ic + bypass cap resitance in parallel with the base resistors. Depending on ic and hfe it's around 8k to 10k.

mac