Sixteen Overdrive Vero layout...

[Toney]

 Ok,
This time it's Erik Hansen's excellent sounding Sixteen Overdrive- so named for the sixteen years of production of the JCM800.
I've done the with-diodes version from the schem here:
http://diy.erikhansen.net/schematics/misc/sixteenoverdrive-diodes.gif

This layout is not tested, as yet, so if anyone wants to give it a read through that would be great.
Opinions/improvements welcome.

  Cheers,Toney.

[MartyMart]

The only "wierd" connection is R4, 1M before Q2's gate, you have a connection from gain pot
which hits Q2's gate "before" that 1M to ground.... perhaps you could move that over, you may need one
more "hole" to do it !
I could be wrong, but its worth a look see

Marty.

[Toney]

 


Cool, thanks Marty...

Done a bit of shuffling and made room for that 680nf cap in the middle too.
Bit more of a comfortable fit

Now looks like so.....     (above)

[vanhansen]

Looks good.  I don't have Veroboard to build it with so I can't verify it that way but following it along with the schematic is checks out ok.
Question:  What's the purpose of C6?  Additional filtering?

It might be a good idea to either remove the pic from the first post or replace it with the updated/corrected pic just to avoid confusion.

Nice job. 

[Toney]

Thanks Erik,

Yes C6 is there for filtering.
I'm building it in the next few days, so I'll report back once verified.
Toney.

[RDV]

I'm your source for good Mallory 50volt .68µF(680nF) caps. They're nice small box style MKTs. Sorry for the spam, but I bought a huge amount on eBay and need to move some. They're the key to the Marshall(bypass cap) sound. Hee Hee. Ten cents a piece or less!

PM me

Please

RDV

[vanhansen]

Cool, Toney.  Looking forward to it.  Once verified I'll add it to my site with the schematic and perf layout.

Ricky, I'm interested in some caps.  It may have to wait until after the holidays though.  From the sound of it it appears you have a large stockpile...LOL.

[Toney]

Built her.....fired right up.....Yes!!

Was only able to test it through the baby amp today...but sweet boost and a leetle crunch.
Didn't get a lot of noticable change with the "soft" pot.
Also fully counter-clockwise gain pot cuts volume too...normal?
Need to test it further with Mr. JCM800.

[Toney]

Stretched the layout a bit too, for the reality of cap sizes.

[vanhansen]

Built her.....fired right up.....Yes!!

Was only able to test it through the baby amp today...but sweet boost and a leetle crunch.
Didn't get a lot of noticable change with the "soft" pot.
Also fully counter-clockwise gain pot cuts volume too...normal?
Need to test it further with Mr. JCM800.

Hey Toney.  Glad to hear it fired up.  I haven't tried the "soft" pot myself yet.  That's a mod from MartyMart.  He played with it quite a bit.  As for the Gain pot, yes what you are experiencing is normal.  Lug 1 goes to ground, just like the Volume.  The JCM800 amps have their pre-amp gain pots wired the same way.  The volume and gain are very interactive on those amps and they should be that way as well with this circuit.

I saved the revamped layout.  Nice work.