Amp Build: JCM800 2204 HG Jose

[FourT6and2]

Wire a small pot like 10k backwards and the wiper takes the place of the ground wire for your coipper array. The less the resistance the lighter the clipper effect, Putting a maybe 120-220p over that pot also dials out fizz so yiu can find a sweet spot balance for highs and drive with any normal preamp gain setting. That is what I call Squash.

About 15-17 k gets you completely out of the audible clipping.

Ah I understand. You're talking about a resistor in series to ground after the clippers. TUT book explains this in one of the chapters. Forgot what the author calls it (compliance and bounding?). But it's to basically limit the effect of the diodes and supposedly make the clipping more "tube like." I think Friedman does this in his SAT switch?

Might try it at some point but not right now. Working on a bypass cap over the voltage divider on Gain 1 to kill some of the fizz. 500pF to 2000pF. Somewhere in there. But it's hard to really hear an audible difference. Sometimes I think I hear it. Sometimes I think it's my imagination.

[Reeltarded]

Im sorry Im like half backwards in my response too because a family member was engaging me in political discourse while calling me away to look at leftovers several times to see if. I thiught they were ok to put in a fridge riple bagged and wrapped in 40 metric tons of foil plus two more bag so the ham juice would not mingle with the turkey which was wrapped the same and about two feet away on a different shelf.

Disaster: Averted. There will be separate flavors in the near future because of metalurgy and ten-zip meat vaults.

I use 100p PI snubbers on the amps that are similar to your's. Also as high as 220p over the resistor that determines clampling for the clipper circuit (10-12k in Jose drawings) but I also put a trimmer on that capacitor so its partial bypass.

One of my amps has no room for the lifting pot so I also threw a 25k trimmer at the junction of the diodes and probably have that in the 7k range. I use a 10k off the CF, so that's 17k in total.

I started oit trying to make a tube amp act like a. Randall RG 80/100/120 and noted the 1n914 pair in those schematics so that is where I started. It's also where I ended after trying every series and values up to 20v that I could find. Basically made every amp sound like the RG amps just by turning on the 914s.

I have found on similar amps that bypassing the plate on stage 2 with 220p to 500p works pretty good for taking the hash off the overall drive. 1Kp also works though if you have higher plate values, which I sort of prefer if I am in a bad mood.

[FourT6and2]

I have found on similar amps that bypassing the plate on stage 2 with 220p to 500p works pretty good for taking the hash off the overall drive. 1Kp also works though if you have higher plate values, which I sort of prefer if I am in a bad mood.

I have the first stage's plate (320K total) bypassed with a 330pF cap. But it's in two stages. 100K bypassed with 330pF cap, then 220K, then the tube socket. I haven't tried other bypass values, nor have I tried bypassing V1b plate. Easy enough to try it. But the bypass on the voltage divider seems to be good.

I also lowered depth cap to 0.0022uF from 0.0047uF. Nice mid boost. You do lose some of the deep low-end but you still get a decent thump. And you can drop the mids slightly to get back the deepness of the 4n7 cap.

Also settled on a 0.001uF bypass on the Gain voltage divider to tame some of the hash noise.

This thing is really coming along and I'm definitely learning a lot as I go. A bit burnt out today though. Spend a few hours A/Bing depth caps and my head hurts haha.

[Reeltarded]

Dont let me talk you into mussing up your pretty amp, but try bypassing on scond stage instead of first if you start tweaking things. It works better in my ears and it feels better to my fingers.

[FourT6and2]

Dont let me talk you into mussing up your pretty amp, but try bypassing on scond stage instead of first if you start tweaking things. It works better in my ears and it feels better to my fingers.

Might try it. I figure the first stage is where it needs it more though, since the plate load is higher.

[pompeiisneaks]

Super cool thanks!

~Phil

[Cathode Ray]

Yeah. It's a make-before-break rotary switch (Alpha). I've got 20v zeners, 18v zeners, MPSA06 transistors, 2N5401 transistors, and 5v zeners.

Man, I was looking for a thread you posted about this a while back.



Could you point me to the thread (maybe it was on rigtalk) showing the details on how you constructed this rotary switch with the clipping options ?


Thanks

[FourT6and2]

Yeah. It's a make-before-break rotary switch (Alpha). I've got 20v zeners, 18v zeners, MPSA06 transistors, 2N5401 transistors, and 5v zeners.

Man, I was looking for a thread you posted about this a while back.



Could you point me to the thread (maybe it was on rigtalk) showing the details on how you constructed this rotary switch with the clipping options ?


Thanks

I don't think I ever explained how to do it. But here you go. It's easy.

Make sure it's a make-before-break switch.
1 deck.
1 pole.
However many positions you want.

Attach clippers to each solder tag. Then attach all the free-standing ends together. Your in and out = junction of all attached components and the single pole of the switch.

Here's a photo of a version I made as a decade box just to test.

[Cathode Ray]

I don't think I ever explained how to do it. But here you go. It's easy.

Make sure it's a make-before-break switch. 1 deck. 1 pole. However many positions you want.

Attach your clippers to each solder tag. Then attach all the free-standing ends together. Your in = junction of all attached components. Out = the single pole of the switch.

Here's a photo of a version I made as a decade box just to test.

Yeah

That's the picture I was thinking of.

Very cool. Thanks

In the end, which clipping components did you prefer ?

[FourT6and2]

Here's a final clip after all the changes.
I'm pretty happy with how it sounds here in the room, but hey I'm no recording engineer.

This is straight in (no boosts or EQ pedals). For a few of the sections I'm running a TC Flashback delay in the loop.
When I'm not running the delay, it's out of the loop (not merely bypassed).

[katopan]

Man, I could listen to that all day long. Great amp!

[Reeltarded]

Sounds great!

[Cathode Ray]

Sounds good

[cbass]

looks and sounds great

[FourT6and2]

Ceriatone is offering this as a kit now haha. I suppose it was inevitable.