peterc52
Well-known member
Is this possible to have one input of super lead and one of 2203? 
H
harddriver
Well-known member
peterc52
Well-known member
Thank you! Have you tried it?
H
harddriver
Well-known member
No I did not but some builders on Metro did and the layout works just fine. What you end up with is the Bright Super lead channel and the high and low input of the 2203 channel from the looks of the layout. Depending on how you wire the DPDT switch you will have the SL and when you pull/or flip the DPDT switch you then have the cascaded 10K cold clipper added to the 2/7K/.68uf which makes a 2203.
The only possible issue I see with the layout is the where the signal goes through the 470K/500pf/470K voltage divider where the 470K goes to ground which bleeds some gain to ground in the 2203 circuit. It looks like the Superlead signal is also going through the same voltage divider whereas it normally would not go to ground at all and simply pass through the 470K/500pf mixer with no signal gain being bled off to ground. It might be possible to figure out a way to put the ground side of the 470K on a switch to lift the ground when in 1959 Superlead mode so no gain is lost in the original 1959 circuit.
Maybe someone else can have a looksee and see if I am seeing things correctly?
All it will cost you is a Dual 1 meg audio pot and a DPDT switch and some wire.
The only possible issue I see with the layout is the where the signal goes through the 470K/500pf/470K voltage divider where the 470K goes to ground which bleeds some gain to ground in the 2203 circuit. It looks like the Superlead signal is also going through the same voltage divider whereas it normally would not go to ground at all and simply pass through the 470K/500pf mixer with no signal gain being bled off to ground. It might be possible to figure out a way to put the ground side of the 470K on a switch to lift the ground when in 1959 Superlead mode so no gain is lost in the original 1959 circuit.
Maybe someone else can have a looksee and see if I am seeing things correctly?
All it will cost you is a Dual 1 meg audio pot and a DPDT switch and some wire.
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ClintN667
Well-known member
Ceriatone has an amp now like this. It's switchable plexi and 800. Look on their site and you should see the layout
Fusionbear
Well-known member
I built one, but I used two separate dpdt switches and an extra preamp tube so there would be no compromise between the two options. I'll draw a layout and post for your consideration later today.
peterc52
Well-known member
Thank you!
Fusionbear
Well-known member
Sorry guys, had to babysit my granddaughter. I'll try again tomorrow.....
M
MxLx
Member
The Granger M50 is a Plexi clone that has a push/pull for “XGAIN” that switches it to cascaded mode.
dcburn
Well-known member
I for one am looking forward to it!
peterc52
Well-known member
@Fusionbear
If you have the time to do this at some point I would be grateful ?
If you have the time to do this at some point I would be grateful ?
peterc52
Well-known member
@Fusionbear whenever you have the time ?
Fusionbear
Well-known member
Here is a picture of a basket case I rebuilt. It ended up sounding amazing....
peterc52
Well-known member
Okay. I have no idea what’s going on here ?
If you have the time for a layout you are very welcome
dcburn
Well-known member
Clean!
Great job!
Fusionbear
Well-known member
Been so busy. Sorry...
First switch just sends the signal to either input of the preamps. In one position to the 2204 tube, in the other, to the SL tube.
The second switch switches between the outputs of the 2204 tube or SL tube to the input of the cathode follower.
That's it in a nutshell. If you look at the picture of the basket case rebuild above, you should be able to figure it out. I put the volume for the SL Normal gain in the back panel as I ran out of room in the front panel... The front panel has the gain for the 2204 and the gain for the bright of the SL. I kept the pre-phase inverter Master volume for both settings to keep it simple.
The SL inputs are permanently jumped.
First switch just sends the signal to either input of the preamps. In one position to the 2204 tube, in the other, to the SL tube.
The second switch switches between the outputs of the 2204 tube or SL tube to the input of the cathode follower.
That's it in a nutshell. If you look at the picture of the basket case rebuild above, you should be able to figure it out. I put the volume for the SL Normal gain in the back panel as I ran out of room in the front panel... The front panel has the gain for the 2204 and the gain for the bright of the SL. I kept the pre-phase inverter Master volume for both settings to keep it simple.
The SL inputs are permanently jumped.
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harddriver
Well-known member
I came across this One Wire switch mod I had for bright channel super lead and then the push/pull 1 meg DPDT switch to engage the cascaded gain stage. You might be able to take some ideas off of this One wire mod. All you have to do is figure out how to keep the Super lead channel going through the 470K/500pf mixer straight through and when you are in 2203 mode the signal would run through the voltage divider 470K/500pf- and then the 470k leg would go to ground as in the 2203 circuit.
