sluckey wrote: ↑Sun Nov 24, 2024 8:53 pm
Who knows what he was thinking. I just drew the schematic to match the layout and never thought too much about it since I never built it.
I also drew schematics for his Dirty 18 and Lite IIB. He used two 100K plate load resistors in both of those amps.
Right on. My guess is that it was a cut-n-paste typo and they should both be 100k/100k, but some mismatch is desirable, tonally, so maybe he intended them to be 82k/100k. Just not switched.
Oh well, carry on....
I do remember this being a very good sounding amp.
sluckey wrote: ↑Sun Nov 24, 2024 7:22 pm
The 82K should be on top and the 100K should be on bottom. Was it intentional or a drawing error? I suspect we'll never know.
Hi Steve,
I was referring to the part choices for the PI. With a Voxy or Marshall 18W PI, the large 47k tail resistor (56k in some early 18W amps) improves balance and the plate loads are typically 100k/100k. In the Plexi PI, with the 10k tail resistor, the 82k/100k pair are to (somewhat) restore the imbalance caused by the 10k tail.
I am wondering if the 82k/100k choice (or at least as drawn) was intentional on Moss's part to cause some imbalance in what is otherwise a Voxy PI and which should have 100k/100k resistors.
What are your preferences? And have you built similar?
I have an old PA just begging for something like this.
"Education is what you're left with after you have forgotten what you have learned" - Enzo
sluckey wrote: ↑Sun Nov 24, 2024 7:22 pm
The 82K should be on top and the 100K should be on bottom. Was it intentional or a drawing error? I suspect we'll never know.
Hi Steve,
I was referring to the part choices for the PI. With a Voxy or Marshall 18W PI, the large 47k tail resistor (56k in some early 18W amps) improves balance and the plate loads are typically 100k/100k. In the Plexi PI, with the 10k tail resistor, the 82k/100k pair are to (somewhat) restore the imbalance caused by the 10k tail.
I am wondering if the 82k/100k choice (or at least as drawn) was intentional on Moss's part to cause some imbalance in what is otherwise a Voxy PI and which should have 100k/100k resistors.
What are your preferences? And have you built similar?
I have an old PA just begging for something like this.
Yes, I've built many 18W variants.
The straight 18W Lite IIb variant with a couple of very minor tweaks is my favorite. Very touch sensitive and a fantastic overdrive. B+ should be 350V rectified. 12V on the EL84 cathodes through 150R. The EF86 front end is pretty killer too. There used to be a really good video of the Foxy 18 on YouTube but I think it got taken down
dorrisant wrote: ↑Sun Nov 24, 2024 9:48 pm
What are your preferences? And have you built similar?
I have an old PA just begging for something like this.
I built my Dual Lite which is a combination of the Foxy 18 and the 18W Lite IIB. I used the iron from a Hammond AO-39. It's a very simple amp with a lot of tone options. I prefer the Vox channel to the Marshall channel. I've built more sophisticated amps but the dual lite is my all-time favorite.
Take a look. You just may need one of these simple amps.
FWIW, I built one of these as per the original layout and it is a favorite of mine. Especially with a telecaster. Sluckey's Dual Lite was on the short list with the iron that I had around. The Foxy 18 seems much more versatile than a Lite IIb - that notch control is a winner.
dorrisant wrote: ↑Sun Nov 24, 2024 9:48 pm
What are your preferences? And have you built similar?
I have an old PA just begging for something like this.
I built my Dual Lite which is a combination of the Foxy 18 and the 18W Lite IIB. I used the iron from a Hammond AO-39. It's a very simple amp with a lot of tone options. I prefer the Vox channel to the Marshall channel. I've built more sophisticated amps but the dual lite is my all-time favorite.
Take a look. You just may need one of these simple amps.
On your Notch/6-pos cap select switch, I noticed you went with a 100nF for the output cap to the common of the 6-pos switch, but omitted the 5.1M switch-pop resistors. Do you get any switch pop without the resistors between the poles?
Colossal wrote: ↑Mon Nov 25, 2024 9:12 pm
On your Notch/6-pos cap select switch, I noticed you went with a 100nF for the output cap to the common of the 6-pos switch, but omitted the 5.1M switch-pop resistors. Do you get any switch pop without the resistors between the poles?
No objectionable pop. That's in part because the 100nF blocks any DC from reaching the tone caps and partly because I used a make before break switch.
And to be a bit more accurate, I should not have said my Dual Lite is part Foxy 18. It's really a basic copy of my AC-15 normal preamp plus the Lite IIB preamp. They are both very similar though and probably sound about the same.
Colossal wrote: ↑Mon Nov 25, 2024 9:12 pm
On your Notch/6-pos cap select switch, I noticed you went with a 100nF for the output cap to the common of the 6-pos switch, but omitted the 5.1M switch-pop resistors. Do you get any switch pop without the resistors between the poles?
No objectionable pop. That's in part because the 100nF blocks any DC from reaching the tone caps and partly because I used a make before break switch.
And to be a bit more accurate, I should not have said my Dual Lite is part Foxy 18. It's really a basic copy of my AC-15 normal preamp plus the Lite IIB preamp. They are both very similar though and probably sound about the same.
I figured the 100nF would dampen pop, but didn't know if it would eliminate it all together. That's cool about the make-before-break switch though. Thanks for clarifying.
