My M800 is apparently a bust

[PKRPedals]

I can't get this pedal to do right. It sounds pretty good when the chord is struck but there is very little sustain and the notes just sort of fizzle out. I've tried a new set of J201's and still the same thing. I have tweaked till I can't tweak anymore and can't get it to act right. So I guess this one will go on the shelf for awhile.

 

[music6000]

I can't get this pedal to do right. It sounds pretty good when the chord is struck but there is very little sustain and the notes just sort of fizzle out. I've tried a new set of J201's and still the same thing. I have tweaked till I can't tweak anymore and can't get it to act right. So I guess this one will go on the shelf for awhile.

My M800 was doing exactly what you describe
All the Trimmers were adjusted to 4.5v & it was meh, no sustain. 4.75, 5v, 5.25v & 5.5v, Louder with no Gain!
Old School, Strummed a Chord each time & tuned each Trimmer by ear til it was at its Fullest.
Did this 3 times as each adjustment effects the other Trimmers.
The Tone Trimmer is actually a Internal Potentiometer.
CCW will yielda a Bigger Brighter Sound, Mine is at 9.00 with 7.00 being Fully CCW
The J201 below it is separate from it & has Fixed Voltage.

Awesome JCM800 Emulation !!!

 

[PKRPedals]

I get what you're saying, but I have done that over and over but just can't get rid of the fizzle out on the notes. It has plenty of gain and volume, just the notes won't ring out like they should. I have went back through and checked components and looked at solder joints but I didn't find anything weird.

 

[PKRPedals]

UPDATE: Lesson learned
Solder transistors into the socket or they might not make good contact. Anyway, I still need to tweak it but it already sounds way better. Thanks to the help of a really good forum member Music6000.

 

[Nostradoomus]

Glad you got it going! I find putting a thin layer of solder on the legs (like pre tinning your wire) can help a lot too.

 

[PKRPedals]

I did get it going but it’s not great, but that just may be me. It still has the tiniest bit of sputter but is way better than it was. The problem is I built the Thermionic Deluxe and it is amazing so everything else has to sort of measure up to that in my mind. It’s all good though, I’ll keep messing with it until I’m happy or it gets put on the shelf.

 

[Nostradoomus]

I’ve always like 5457s in J201 circuits...I made a sunn model T preamp that acted much the same as your 800 until I put 5457s in it.

 

[PKRPedals]

I’ll try that next time I need J201’s. I also read that J112 were a good sub as well. These are soldered I’m so it would be too much trouble to try and change them. I haven’t had too much luck with the JCM style circuits. I built the one from PCB Mania and it wasn’t great either. I also think the trimmers that I have been using aren’t very good. I’m going to order some of the Cermet trimmers next time.

 

[Jovi Bon Kenobi]

So far I've had a couple builds with j201s. FWIW, they came alive when I used Siliconix branded one's. They had better gains for each application I guess...in the .80mA to .90mA range. The Fairchild j201s I tested had way lower gain, like around .35mA to .50mA. The difficulty is sourcing Siliconix j201s though.

 

[PKRPedals]

J201’s in general are hard to find. The ones I used are Fairchild though. I’ve used them in other builds and they are good. It just seems the JCM style circuits don’t turn out good for me.

 

[Barry]

I built a KOTB (King of the Brits) from GuitarPCB using J201's that sounds awesome, it's a hotrodded JCM circuit

 

[PKRPedals]

I also built the KOTB and wasn’t impressed with it. I couldn’t seem to get the gain out of it that is is supposed to have. In the video of the KOTB, it has a lot more gain than I could get from mine. Maybe I just suck at building JCM pedals. Haha

 

[Barry]

Where were you buying your J201's? there are lots of fakes out there

 

[PKRPedals]

The ones I have now I got from pedalhacker on reverb

 

[Barry]

I think I bought mine from GuitarPCB when he offered them

 

[Barry]

I had to build three more KOTB's for friends that wanted them after hearing mine.

 

[PKRPedals]

That’s where I got the ones that I used in my KOTB. Actually the KOTB was the first pedal I built because that what I was looking, that hot rod Marshall sound.

 

[PKRPedals]

pretty much everything I’ve built has turned out great except for the Marshall style pedals. I’ve built quite a few of the Guitar PCB circuits and they all turned out good except for the KOTB and the Plexi Plus, neither one of those really wowed me.

 

[Barry]

Maybe I've just got the wrong Marshall tone in my head

 

[PKRPedals]

No it’s probably me just expecting a miracle