"London 2 Step" amp sim schem for you ...

[MartyMart]

http://aronnelson.com/gallery/Martys-layouts-and-photos/London_2_Step_ampsim?full=1

A simple 2 stage amp sim/overdrive using a pair of J201's.
Nice "spanky" middle tone to it, not a "metal" pedal but capable of
totally clean to quite a crunchy overdrive setting.
Also has a healthy boost in volume, even when clean.
Hope someone builds and enjoy's it

Marty.

[StephenGiles]

Looks very nice Marty, where are you getting your J201s these days?
Stephen

[jmusser]

It looks like a pretty simple build Marty. I'll have to give it a try. I think the only thing I'll have to scratch around for, is the 100k trimmers. Do you have a ball park resistance that you had to adjust your 100Ks to to get 4.5V? I know that'll have to do with the the tolerances of the other components, and the voltage of your battery, but If I could get close, I might fiddle around with fixed values to get the bias on the J201s. How was Italy? Great I'm sure!

[MartyMart]

Stephen, I'm getting them online from a guy that RDV put me onto "Dpi4parts" is his ebay id
50 J201's for around 9 dollars.
Peter is his name:
dpi4parts@worldnet.att.net

Jeff, you'll need to get 100k trim pots, as all Jfets are different, ( gain- bias etc ) so I can't begin to guess
what value is needed ... I've tried with resistors and failed .. !!
Italy was great, I would recommend a trip to Venice ... but don't go in high summer ... it stinks !!

MM

[RLBJR65]

Marty, as you pointed out this is not way far off from the FireFly Sim I posted in this thread.
http://www.elixant.com/~stompbox/smfforum/index.php?topic=42526.0;topicseen
I'm gonna try some of your suggestions out BTW. V2 is in the works already

Anyway I'm sitting around in a hotel room tonight and really board so hacked up my layout and did this one for the 2 step. Layout looks ok but I have not built it. http://aronnelson.com/gallery/Richard-Boop-RLBJR65/London2Step

Richard

[MartyMart]

Richard, you've got the 100uf cap connected from input to ground !
is that the power filter cap ? ... then 9v to ground ( need to move/trace cut )
Also the 15n from Q2 connecting from the trim pot pin 2 might be wierd ?
Should be pin3/Q1 drain
Thanks for bothering to "draw it up" though ... appreciated

MM.

[RLBJR65]

OK, thanks I moved the filter cap Not following you on the last bit though.
http://aronnelson.com/gallery/Richard-Boop-RLBJR65/London2Step

Q2 trim pot pin 1 to V+, Pin 2 (wiper) and pin 3 are both connected to the drain as is the15n.
Am I missing something?

Richard

[MartyMart]

Sorry ... I meant Q1 15n looks wierd ... it's connected to the wiper of the trim pot
that may cause a problem ..?? .... perhaps not !

MM.

[RLBJR65]

Thanks Marty. Yes, now that you pointed it out that does look really weird.
It will work though because the trim pots wiper, pin 3, Q1 drain and the 15n all share a common connection. Doesn't really matter in what order they are connected.

BTW, I like the challenge of doing layouts (If their not to tough and I'm in the mood anyway) especially if it's for something I'm interested in, plan on building sometime or have built and think others would like. Also it gives me a chance to contribute something back to the forum.


Richard

[Jered]

Stephen, I'm getting them online from a guy that RDV put me onto "Dpi4parts" is his ebay id
50 J201's for around 9 dollars.
Peter is his name:
dpi4parts@worldnet.att.net

hehe...Marty, his name is Dan Peters, really nice guy and he has a lot of stuff real cheap. He lives about a mile from me which makes it very easy when I need stuff. He sells me a lot of his surplus too. I just got a bag of 500 amber LED's for $5. If there is stuff you need that you don't see on his ebay pages, ask him about it, he can probably get it for you, he has a lot of aquaintances in the SoCal electronics comunity.
  Jered

[bwanasonic]

I don't work with vero, but wouldn't you want to cut all the traces under that jumper that runs between the grounds at opposite sides of the board? It seems like a potential short to ground for the rows where the trace isn't cut.

Kerry M

[MartyMart]

I don't work with vero, but wouldn't you want to cut all the traces under that jumper that runs between the grounds at opposite sides of the board? It seems like a potential short to ground for the rows where the trace isn't cut.

Kerry M

No Kerry, jumper is on top of board, the view is "see through" so the copper traces
are underneath 

MM.

[bwanasonic]

No Kerry, jumper is on top of board, the view is "see through" so the copper traces
are underneath 

Ah hah! The purple color coding should have tipped me off.

Kerry M

[StephenGiles]

Marty, I lurched over to SSI in Carshalton lunch time today and bought some MPF102 - for £1.20 each + VAT, so at last I'll see what these amp simulators sound like. They don't stock J201s unfortunately.
Stephen

[MartyMart]

Ouch !! that's too much Stephen ... check your PM's

MM.