Second master and gain on 2203

[giordydiver]

Hi, I want make a new mod in my amp, something like a second channel to have clean/ dirty, dirty/lead ecc so I think to put a second gain pot and a second master to make it switching to channel by a two way switch on front panel and by footswitch. What do you think? How can i do the footswitch system?

[SteadyEddie]

Relays. Doug Hoffman has done relay kits and so does mojotone. I posted something similar for a mod I want to do for my 2204 with a gain boost and someone mentioned colossal amps has relay switching kits also. I like Doug's. They pretty much involve rectifying the AC voltage from your heaters.

I like your idea. Now if I can find some concentric pots, I'll be in business.

[SDM]

With the wipers tied as drawn, adjusting one pot of a set will always effect the other, they'll interact. Easy way to see this, imagine one master (or gain) is set to zero, other is cranked. Both will be silent as both wipers (and hence the signal) are grounded out by the one pot set to zero.

Common way switching is done in your situation is to switch the wipers instead. So, for the masters, treble pot wiper connects straight to both masters, both masters are always grounded. Only wipers are switched. You'll likely want to add a resistor to ground at the PI input cap side to maintain a DC reference there to minimize popping while switching. Would also want this added resistor at input to the triode after your gain pot switching to give the grid there a DC reference during switching/reduce popping in this example.

More ways to go about it, but that would be a very common way for your example using relays. Keep in mind the pot overall values will always in parallel, may influence pot choice. Same for DC reference resistors, usually a high value is chosen for those to limit impact on all else. With your example, switching the wipers instead will give you fully independent controls though, no interaction. Typically what people desire.

[giordydiver]

So , i change my idea of double gain and master to mada e real clean channale. I like clean of low imput and i thing something like this.what do you thing? About popping ,where I must install resistor?


http://s7.postimg.org/4f8j93rzf/image.jpg
If i use my first idea is correct in this way?
http://s13.postimg.org/6r5i3xi3r/image.jpg


I think another way, hi gain imput is clean with gain to 4/5, so i think to not bypass valve and use only secod gain pot but before use a 100k in series to degrease imput and have more clean range, for the volume level dont use a second master but install a resistor in series to master to degrease volume when i use distorterd channel, and bypass the resistor on clean. Can be a right way or not? Also the resitor in series to pot can change the tone/ frequencies response?

[giordydiver]

So I modified the schematic with switches with both input and output of the pots and added the divider 470k / 470k first of the gain clean. Take the schematic and did the layout for double relay. I have no experience with relay so I hope I have done everything right. Else, by reading various posts here on the forum I read that I have to connect to the ground relay with resistance, I explained politely howI have to do everything?

http://s17.postimg.org/whduu6dsv/image.jpg
http://s24.postimg.org/wayx36tud/image.jpg

[Am_I_Evil]

Hi, I modified my Marshall JCM800 with one more footswitchable volume, and it works great.

http://www.ampspecs.com/marshall-jcm800 ... olo-boost/