Thoughts on my Jose 2204

[FourT6and2]

Looks like a sweet Jose variant! Do you prefer passive loops? I think a secondary PPIMV would also be sweet for low-volume sessions. I have a Xenrelic custom with a similar configuration for the gain modes, but with a lossless loop. It's pretty sweet!

I prefer tube-buffered loops but a passive loop is just easier to build haha. I only use a delay pedal in the loop and it's buffered, so it seems to work just fine. No need for a PPIMV as these amps sound great at low volume thanks to the zeners.

Yes, at least until you bypass them! For my Xenrelic I made the clipping modes foot-switchable with a second sub-master volume to account for the volume difference and get the best of both.

Totally. Except I only know one chord and I chug away at it for an hour straight lol. So I have no need for a clean sound

 

[CrazyNutz]

Why use linear pots for the gains? I think most amps use log/audio, no?

I've been thinking about the CCV style Depth too. Might give it a try. Do you also have the "thump" switch or just the pot and all the caps?

Linear pots on the gains gives you a better range of sweetspot, I find the audio tapers tend to bunch up the gain as you get closer to the end of the taper. Also call me crazy but the linear pots sound better.

Also for the master volume, use a reverse audio taper.

For the depth, the switch engaged (resistor in) sounds best to me. I've seen the resistor be 27k to 39k. As for the nfb resistor/tap, usually come off the 8ohm, 39k-100k figure out what sounds best, i've seen the nfb resistor before, and sometimes after the depth.

Also on your schematic where it says "no dropper" you should put a 10k there to separate those power nodes. I would just do all 10k's across the board.

 

[FourT6and2]

Why use linear pots for the gains? I think most amps use log/audio, no?

I've been thinking about the CCV style Depth too. Might give it a try. Do you also have the "thump" switch or just the pot and all the caps?

Linear pots on the gains gives you a better range of sweetspot, I find the audio tapers tend to bunch up the gain as you get closer to the end of the taper. Also call me crazy but the linear pots sound better.

Also for the master volume, use a reverse audio taper.

For the depth, the switch engaged (resistor in) sounds best to me. I've seen the resistor be 27k to 39k. As for the nfb resistor/tap, usually come off the 8ohm, 39k-100k figure out what sounds best, i've seen the nfb resistor before, and sometimes after the depth.

Also on your schematic where it says "no dropper" you should put a 10k there to separate those power nodes. I would just do all 10k's across the board.

Any more info about the dropper? I know most amps have a 10K there. The last 3 I built, I didn't use it (admittedly, I just did that because I was starting with a Ceriatone layout and they don't use a dropper. The amps sound pretty good to me. I figure I want to keep the preamp voltages higher for a tighter feel/sound. Is there any reason why that's a bad idea? Without the dropper, I'm JUST hitting the voltages I want. With another dropper there, I think the voltages would be too low. I've been going back and forth on it. Maybe I'll just try it this time.

 

[psychodave]

My first thought was also a CCV-style depth, you could use a pull pot if you don't want another switch. You'll probably have to play with that resistor, seems MC used a few different values.

I don't have a good explanation why but I'd put that .001u snubber on the other side of the 68k grid stopper on V1.

You're talking about the 27K used in the CCV Depth? What am I looking for regarding that resistor value? Does it depend on NFB or anything else or just a preference thing? I want to avoid another switch. So maybe a push/pull.

I've tried that snubber cap in a few different positions. Doesn't seem to make a huge difference. But I'm open to learning why it might be better to swap its position.

I don't think it was always 27k, esp in the MC built ones but I could be wrong. Others here know for sure. I tried 27k/33k/39k/47k but in my amp (Ceriatone KK) I liked 82k. And I almost always used that switch position, with the 82k 'IN'.

That resistor is something Mark fine tuned. I posted in another thread what was in my CCV... I’d post it now but I forgot.

 

[psychodave]

Regarding the zeners, I like the idea of a rotary switch and using 5v all the way up to 20v. It just adds a lot more versatility.

 

[FourT6and2]

Regarding the zeners, I like the idea of a rotary switch and using 5v all the way up to 20v. It just adds a lot more versatility.

I've thought about it. But if I have too many options I tend to fiddle more with the amp than play guitar. I might make a "zener decade box" so I can test a bunch of different values by just clipping it into the circuit. And then go with the two options I like the most. I can do that with one of my current builds. Just clip one end to the master and the other to ground.

How cool would it be if there were a variable zener? Like a potentiometer version of a zener. And you could have "infinite" adjustability from like 4v - 24v.

 

[CrazyNutz]

Any more info about the dropper? I know most amps have a 10K there. The last 3 I built, I didn't use it (admittedly, I just did that because I was starting with a Ceriatone layout and they don't use a dropper. The amps sound pretty good to me. I figure I want to keep the preamp voltages higher for a tighter feel/sound. Is there any reason why that's a bad idea? Without the dropper, I'm JUST hitting the voltages I want. With another dropper there, I think the voltages would be too low. I've been going back and forth on it. Maybe I'll just try it this time.

Those interstage droppers play a few important roles:
1) They decouple the amplifier stages. Without it your Cath follower, and PI Stages are coupled, and can interact
2) Provide a local energy supply for sudden current demands. Without it, your Cath follower could be robbing power from the PI, and vice versa.
3) Further smooth, and reject ripple.

If you wan't higher preamp voltage it's customary to adjust the first dropper where the voltage enter the preamp.

Also if you like the higher voltage, you may want to lower the plate resistor on V1A from 390k to 330k

you can read more here: http://www.valvewizard.co.uk/smoothing.html

 

[psychodave]

Regarding the zeners, I like the idea of a rotary switch and using 5v all the way up to 20v. It just adds a lot more versatility.

I've thought about it. But if I have too many options I tend to fiddle more with the amp than play guitar. I might make a "zener decade box" so I can test a bunch of different values by just clipping it into the circuit. And then go with the two options I like the most. I can do that with one of my current builds. Just clip one end to the master and the other to ground.

How cool would it be if there were a variable zener? Like a potentiometer version of a zener. And you could have "infinite" adjustability from like 4v - 24v.

I agree about tinkering, but after a while I tend to like one or two. That might be a good temp option then replace the rotary for a 3 way.

That would be awesome to have an infinite zener.

Also, I like to try different caps on the gain pot for different zeners. .0022 or .0047 doesn’t always sound good for 5 or 15 volt zeners.

 

[FourT6and2]

Any more info about the dropper? I know most amps have a 10K there. The last 3 I built, I didn't use it (admittedly, I just did that because I was starting with a Ceriatone layout and they don't use a dropper. The amps sound pretty good to me. I figure I want to keep the preamp voltages higher for a tighter feel/sound. Is there any reason why that's a bad idea? Without the dropper, I'm JUST hitting the voltages I want. With another dropper there, I think the voltages would be too low. I've been going back and forth on it. Maybe I'll just try it this time.

Those interstage droppers play a few important roles:
1) They decouple the amplifier stages. Without it your Cath follower, and PI Stages are coupled, and can interact
2) Provide a local energy supply for sudden current demands. Without it, your Cath follower could be robbing power from the PI, and vice versa.
3) Further smooth, and reject ripple.

If you wan't higher preamp voltage it's customary to adjust the first dropper where the voltage enter the preamp.

Also if you like the higher voltage, you may want to lower the plate resistor on V1A from 390k to 330k

you can read more here: http://www.valvewizard.co.uk/smoothing.html

Great, thanks for the info. I've tried 330K on the V1a plate. Been going back and forth with that value. I've tried 220K up to 470K. 330/390 is about where I've settled. Will start with 10K droppers (including the first one) and 330K plate.

 

[FourT6and2]

Also, I like to try different caps on the gain pot for different zeners. .0022 or .0047 doesn’t always sound good for 5 or 15 volt zeners.

You're talking about which cap? The bright cap? Yeah, easy enough to play around there.

 

[psychodave]

Any more info about the dropper? I know most amps have a 10K there. The last 3 I built, I didn't use it (admittedly, I just did that because I was starting with a Ceriatone layout and they don't use a dropper. The amps sound pretty good to me. I figure I want to keep the preamp voltages higher for a tighter feel/sound. Is there any reason why that's a bad idea? Without the dropper, I'm JUST hitting the voltages I want. With another dropper there, I think the voltages would be too low. I've been going back and forth on it. Maybe I'll just try it this time.

Those interstage droppers play a few important roles:
1) They decouple the amplifier stages. Without it your Cath follower, and PI Stages are coupled, and can interact
2) Provide a local energy supply for sudden current demands. Without it, your Cath follower could be robbing power from the PI, and vice versa.
3) Further smooth, and reject ripple.

If you wan't higher preamp voltage it's customary to adjust the first dropper where the voltage enter the preamp.

Also if you like the higher voltage, you may want to lower the plate resistor on V1A from 390k to 330k

you can read more here: http://www.valvewizard.co.uk/smoothing.html

Great, thanks for the info. I've tried 330K on the V1a plate. Been going back and forth with that value. I've tried 220K up to 470K. 330/390 is about where I've settled. Will start with 10K droppers (including the first one) and 330K plate.

I tend to like 330. Just adds a touch more clarity to the sound. That said, my old Cameron 50 watter has a 430k resistor (or something around that value).

 

[V2a]

what's the reasoning behind the 47n coupling caps that follow the PI? Bias excursion and recovery will increase a bit. I'd go back down to 22n.

 

[V2a]

Yes, that's basicaly what I was getting at: the cap is not placed after a resistor to create a low pass filter. Just snubbing signal directly to ground."

The R and C in the photo do form a low-pass filter.

 

[V2a]

I can also always use a plate bypass cap instead. That's another can of worms. Because I can go with:

330K resistor bypassed
100K resistor bypassed with 220K in series
220K bypassed with 100K in series
220K in series with 100K that's bypassed
100K in series with 220K that's bypassed

Does it make a difference what order it's in or if it's just a single bypassed resistor? I've seen it done in each of these ways.

The order of the series Rs does not matter unless you take the output from the intersection of the Rs rather than from the anode.

 

[SpiderWars]

I can also always use a plate bypass cap instead. That's another can of worms. Because I can go with:

330K resistor bypassed
100K resistor bypassed with 220K in series
220K bypassed with 100K in series
220K in series with 100K that's bypassed
100K in series with 220K that's bypassed

Does it make a difference what order it's in or if it's just a single bypassed resistor? I've seen it done in each of these ways.

The order of the series Rs does not matter unless you take the output from the intersection of the Rs rather than from the anode.

I've seen the series resistors with the 100k bypassed in schematics but I assumed it was because they were using an existing 100k board resistor and then adding a 220k at the socket (and also relocating the cap to the socket).

That said, my homebrew Jose has a 100k//470p then in series with a 270k.

 

[FourT6and2]

I tend to like 330. Just adds a touch more clarity to the sound. That said, my old Cameron 50 watter has a 430k resistor (or something around that value).

What's the cathode arrangement on that stage though? Usually the plate resistor and cathode resistor/bypass cap work together to bias the stage, no?

 

[FourT6and2]

what's the reasoning behind the 47n coupling caps that follow the PI? Bias excursion and recovery will increase a bit. I'd go back down to 22n.

0.022uF is tighter low-end, but brighter. 0.1uF has deeper lows, but a bit looser. 0.047uF is halfway between. Tighter than 0.1, but more low-end than .022.

I'm no engineer/tech, just a hobbyist, so can you explain what's up with bias excursion and recovery and why these three different values of capacitor matter outside of "tone"? Plenty of amps with similar circuits used these values.

 

[V2a]

I can also always use a plate bypass cap instead. That's another can of worms. Because I can go with:

330K resistor bypassed
100K resistor bypassed with 220K in series
220K bypassed with 100K in series
220K in series with 100K that's bypassed
100K in series with 220K that's bypassed

Does it make a difference what order it's in or if it's just a single bypassed resistor? I've seen it done in each of these ways.

The order of the series Rs does not matter unless you take the output from the intersection of the Rs rather than from the anode.

I've seen the series resistors with the 100k bypassed in schematics but I assumed it was because they were using an existing 100k board resistor and then adding a 220k at the socket (and also relocating the cap to the socket).

That said, my homebrew Jose has a 100k//470p then in series with a 270k.

This is what is called a partial bypass. The R (bypassed) and C values determine the cutoff as usual, while the values of the two resistors determine how much attenuation you'll get above the cutoff.

 

[V2a]

what's the reasoning behind the 47n coupling caps that follow the PI? Bias excursion and recovery will increase a bit. I'd go back down to 22n.

0.022uF is tighter low-end, but brighter. 0.1uF has deeper lows, but a bit looser. 0.047uF is halfway between. Tighter than 0.1, but more low-end than .022.

I'm no engineer/tech, just a hobbyist, so can you explain what's up with bias excursion and recovery and why these three different values of capacitor matter outside of "tone"? Plenty of amps with similar circuits used these values.

Have a look at this site (it's also covered in Merlin Blencowe's books and other books too
https://robrobinette.com/Tube_Guitar_Am ... Distortion

There is also a calculator on amp books.com.

In short, too much bias excursion and recovery time leads to bad distortion. The amp might get a case of the farts.

 

[fusedbrain]

Big thank you to V2A and CrazyNuts for posting those links.

That's some great reading right there

That power supply info is very timely for a project I have on the bench now.