Schematic for Jose Build
- Thread starter FourT6and2
- Start date
psychodave
Well-known member
Interesting take on it. Like a mix of other modders into one.
FourT6and2
Well-known member
psychodave":5gerjaat said:
Yep, that's exactly what it is.
NewReligion
Active member
FourT6and2":2blfbfh2 said:
Sounds great FourT6and2. I count 14 different value and or addition/subtractions to my circuit take. Of course they all add up.
What are you using for Iron?
David...♫
FourT6and2
Well-known member
glpg80":i0afi9bb said:
The clearest way to describe the differences is to read the schematic and compare to any others you find.
NewReligion":i0afi9bb said:
PT: Merren 1202-55
OT: Merren 784-139
Choke: Metro 352-114
NewReligion
Active member
FourT6and2":3ac5uolq said:
Very nice. Thank you.
David
fusedbrain
Well-known member
I see where you are using a 330pf snubber cap on the 100k plate resistor a la Friedman etc..vs a cap to ground as seen in the Ceriatone Chuppa / Yeti and some Fortin schemes. Just curious about your thoughts on the 2 options and if you tried both methods in this amp?
Amp sounds great by the way
Nice job!
Edit: just noticed the 1n cap to ground over the 68k.
Still interested on your take on plate snubbers....thanks!
Amp sounds great by the way
Nice job!
Edit: just noticed the 1n cap to ground over the 68k.
Still interested on your take on plate snubbers....thanks!
FourT6and2
Well-known member
fusedbrain":2q9x88u0 said:I see where you are using a 330pf snubber cap on the 100k plate resistor a la Friedman etc..vs a cap to ground as seen in the Ceriatone Chuppa / Yeti and some Fortin schemes. Just curious about your thoughts on the 2 options and if you tried both methods in this amp?
Amp sounds great by the way
Nice job!
Edit: just noticed the 1n cap to ground over the 68k.
Still interested on your take on plate snubbers....thanks!
I've tried caps in lots of places to kill highs: plate bypass, after a coupling cap to ground, from grid to ground before the grid stopper, from grid to ground before the stopper (which would be the same as from gain wiper to ground), bypassing that 68K "feel" resistor, bypassing the NFB resistor, etc.
They all have slightly different results. Just depends on your tastes and the specific amp. Gotta try them all on your specific amp/build and see what sounds the best. That's why I just use a decade box that clips in and I can cycle different cap values until I find one I like.
NewReligion
Active member
I found adding a voicing pot (50kL with 500pf & .002uf) does wonders to shape the depth. Not that your build needs it. I like it as I tried many different power tubes and this aided in leveling the playing field.
David
David
fusedbrain
Well-known member
FourT6and2":1o361m9g said:fusedbrain":1o361m9g said:I see where you are using a 330pf snubber cap on the 100k plate resistor a la Friedman etc..vs a cap to ground as seen in the Ceriatone Chuppa / Yeti and some Fortin schemes. Just curious about your thoughts on the 2 options and if you tried both methods in this amp?
Amp sounds great by the way
Nice job!
Edit: just noticed the 1n cap to ground over the 68k.
Still interested on your take on plate snubbers....thanks!
I've tried caps in lots of places to kill highs: plate bypass, after a coupling cap to ground, from grid to ground before the grid stopper, from grid to ground before the stopper (which would be the same as from gain wiper to ground), bypassing that 68K "feel" resistor, bypassing the NFB resistor, etc.
They all have slightly different results. Just depends on your tastes and the specific amp. Gotta try them all on your specific amp/build and see what sounds the best. That's why I just use a decade box that clips in and I can cycle different cap values until I find one I like.
Yeah, lots of different Jose schemes out there and lots of things to experiment with for sure.
I'm working on modding a 1987xl re-issue into one of these Jose type amps right now, so that's why I asked.
I'm retro-fitting the original Marshall ST1 PCB, so I'm using SBE 225P caps throughout as they fit into the board. Just that fact alone will have a big effect on what value components I end up with and where they go.
I still have a few things to work out, but hopefully I can come up with something that sounds halfway decent.
I started with this concept, and tweaked from there. There are a few issues with this scheme, but it seemed like a cool place to start.
Interestingly, the scheme is labeled as a Fortin Cali, but it's very close to a Ceriatone Chuppa
FourT6and2
Well-known member
fusedbrain":3e00wcp7 said:
Right. Because all these Jose amps are the same. And yes, the Chupa is very close to whatever amp this Cali mod schematic was based on. I've built that schematic before too.
It sounds good, but the schematic I posted in the OP is where I ended up after building a bunch of Jose variants.
NewReligion
Active member
fusedbrain":1uf1u8z2 said:FourT6and2":1uf1u8z2 said:fusedbrain":1uf1u8z2 said:I see where you are using a 330pf snubber cap on the 100k plate resistor a la Friedman etc..vs a cap to ground as seen in the Ceriatone Chuppa / Yeti and some Fortin schemes. Just curious about your thoughts on the 2 options and if you tried both methods in this amp?
Amp sounds great by the way
Nice job!
Edit: just noticed the 1n cap to ground over the 68k.
Still interested on your take on plate snubbers....thanks!
I've tried caps in lots of places to kill highs: plate bypass, after a coupling cap to ground, from grid to ground before the grid stopper, from grid to ground before the stopper (which would be the same as from gain wiper to ground), bypassing that 68K "feel" resistor, bypassing the NFB resistor, etc.
They all have slightly different results. Just depends on your tastes and the specific amp. Gotta try them all on your specific amp/build and see what sounds the best. That's why I just use a decade box that clips in and I can cycle different cap values until I find one I like.
Yeah, lots of different Jose schemes out there and lots of things to experiment with for sure.
I'm working on modding a 1987xl re-issue into one of these Jose type amps right now, so that's why I asked.
I'm retro-fitting the original Marshall ST1 PCB, so I'm using SBE 225P caps throughout as they fit into the board. Just that fact alone will have a big effect on what value components I end up with and where they go.
I still have a few things to work out, but hopefully I can come up with something that sounds halfway decent.
I started with this concept, and tweaked from there. There are a few issues with this scheme, but it seemed like a cool place to start.
Interestingly, the scheme is labeled as a Fortin Cali, but it's very close to a Ceriatone Chuppa
There are so many variations on this circuit. On this R11 (Drop R) looks a bit stiff but may suit this variant well. I use a single 2 watt 10k as seen in the Schematic provided by FourT6and2. Also the 820 cathodes are interesting. I never tried a jose with all three cathodes at that value.
Mark told me he had a one off CCV he did. He didn't have any 2.7k resistors so he used 3k on cathodes. As you can see on the Ceriatone Yeti Nik used 3k's. There were some other things that confirmed a reverse engineer at some point of that CCV.
I tune to my ear and check voltages but every amp is a bit unique due to OT's etc...
Thanks for the posting.
David
fusedbrain
Well-known member
Yes, I think all these different Jose variants need to be tweaked to suit personal taste, and also to mesh with the donor amps transformer set and voltages etc... I also think one needs to build a few of these different "Jose" amps to see how they all work and sound, so you can hone in on "the sound in your head" so to speak. I'm working on that now
The main thing that intrigued me in the schematic I posted was the "fizz control" idea with the 2 x 1nf caps to ground. I have only used the plate load snubber cap method in the past, and wanted to try this idea. It seems to be working effectively in my amp so far, but we'll see.
Thanks to both of you guys for replying. You clearly know how to build very good sounding amps, and I appreciate the insight.
psychodave
Well-known member
Like David said, I went with standard values and tweaked with my ear. For example, my Jet City 20 uses 47pf snubbers with 2.7/ 1.0 on both cathodes on V1. V1 a/b resistors are .002 as I needed the amp to track a little faster/tighter. My depth is .0047, but shockingly, I found an old Erie .0033 cap that was magical sounding. The second I popped it in, the amp had “that” tone. I wanted a little more and added a different make of cap in parallel to get me to .0043. To really make things really interesting, I had another Erie cap as my other one and it was .0047, and it didn’t have the same magic.
FourT6and2
Well-known member
NewReligion":ts5r3327 said:
I think you mean soft? 22K dropper will make the amp much looser and more gainy. But... it depends on what the starting voltage is. Maybe that particular amp had a really high B+. That's why you can't just use any old schematic verbatim. There are lots of components in an amp that must be tuned specifically for that amp. Like the B+ dropper. If the B+ is like 500V, then maybe a 22K dropper makes sense. But if the amp has a 425v B+, the a 22K dropper is going to equal mush city.
That's what's in the Ceriatone Chupacabra.
NewReligion
Active member
FourT6and2":df7toilk said:
Indeed I did, thanks for the catch. Been a rough couple of days not sleeping due to colitis. TMI lol. Yes soft and mushy.
fusedbrain
Well-known member
Yup, classic example of fitting the mods to the amp at hand. I'm dealing with this now in my amp.
For example, in a stock 1987xl,the first droppers after the choke are 2 x 10k's in series, but my PT is only putting out 460v B+.
After subbing in a 330k plate load resistor on the first triode, the plate voltage there is only 105v .
That ain't gonna work for what I'm after from this amp, that's for sure!
FourT6and2
Well-known member
fusedbrain":3puka4k3 said:
You can probably go down to 10K on that dropper then. I have a 5-watt, 50K pot that I clip in for the B+ dropping resistor and tune the amp with that. Then solder in the final value.
fusedbrain
Well-known member
Yeah, great idea. I'd love to do that, but where the hell do you get a 5watt pot??FourT6and2":2dsjge2l said: