Lumpy's Tone Shop - Lemon Drop

HamishR · Post by **HamishR** » 11 May 2020, 04:12

Quick note for the 3-knob version - the trimmer spans 4 rows, not the usual three! It's easy with the trimmers i use to bend the middle leg a bit to make it span further. You can see I have tried to indicate that in the layout. It shouldn't make contact with the row above.

Nocentelli · Post by **Nocentelli** » 11 May 2020, 08:46

HamishR wrote: ↑11 May 2020, 04:09 Lemon Drop 4-knob.png

Does the BJT emitter also need a DC resistance path, i.e. a fixed 1k to ground as well as the AC path via the pre-gain pot cap?

HamishR · Post by **HamishR** » 11 May 2020, 09:47

I honestly don't know. I drew these from a trace at Guitar FX Layouts. There is a thread on the forum there.

ch ra · Post by **ch ra** » 11 May 2020, 16:02

This is awesome, thank you for the fast response!

Do you know how the 5 knob one is set up? Looks like there are separate bass and treble pots. https://www.lumpystoneshop.com/7-series-overdrive.html

Also, you said that the 3 pot version sounds better than 4. How do the two compare with pre-gain maxxed out?

Nocentelli · Post by **Nocentelli** » 11 May 2020, 16:27

Nocentelli wrote: ↑11 May 2020, 08:46
HamishR wrote: ↑11 May 2020, 04:09 Lemon Drop 4-knob.png
Does the BJT emitter also need a DC resistance path, i.e. a fixed 1k to ground as well as the AC path via the pre-gain pot cap?

HamishR wrote: ↑11 May 2020, 09:47 I honestly don't know. I drew these from a trace at Guitar FX Layouts. There is a thread on the forum there.

My mistake, I didn't spot "pregain-1 to ground" noted at the bottom of the layout.

HamishR · Post by **HamishR** » 14 May 2020, 01:26

I'll have to go back and compare. I think they sounded quite similar with pregain all the way up but personally I think the pregain is kinda useless. The sound is very "transistory" and harsh where the 3-knob is pleasantly primitive in that old-school Led Zeppelin way.

I have no idea how they may have done a bass and treble version but I did my own which works.

I can't remember what I used for the tone pot - possibly B10K?

HamishR · Post by **HamishR** » 14 May 2020, 01:35

Here it is:

drewl · Post by **drewl** » 22 Mar 2021, 19:24

So in a fit of boredom at work, I built one of these a couple weeks ago using the layout below.

It's oscillating really bad with from Q1 with gain or volume up halfway.
Increasing the 10pf across Q1 kills the oscillation but it sounds too muddy.
I need to clean up the layout, I just slapped the parts on a board.

Anyway, this one sounds really damn good.
Real heavy, loud, full output, not too fuzzy or splatty.
Think I'll swap the 6.8K to Q2 with a trimmer and see what changing the bias does.

drewl · Post by **drewl** » 24 Mar 2021, 19:30

Well just to follow up, lowering the 22K collector resistor to 10K kills just about all the oscillation without altering tone.

Since it has such a high level output I was thinking of adding some clipping diodes to the output, either switchable or with a blend pot for some nasty fuzzy fun.

definitely some raucous sounds from this design.

rockola · Post by **rockola** » 25 Mar 2021, 06:37

I did a PCB for this, have been too busy to do a verification build though. KiCad files at https://github.com/rockola/gota-de-limon

Sinzu L.J · Post by **Sinzu L.J** » 06 Apr 2021, 21:25

HamishR wrote: ↑11 May 2020, 04:12 Quick note for the 3-knob version - the trimmer spans 4 rows, not the usual three! It's easy with the trimmers i use to bend the middle leg a bit to make it span further. You can see I have tried to indicate that in the layout. It shouldn't make contact with the row above.

So, trimmer should be connected to D7. I thought that blue line was a jumper.
Glad to read this

Thanks Hamish !

Cpt Adama · Post by **Cpt Adama** » 01 Apr 2022, 21:53

Does any one have any info, schematics, layouts for the latest 5 knob version?

For the price he is asking for these I would rather just buy it, than go through the work to build this, but it's not available on his site now and he is completely non-responsive to my email enquiries.

Lumpy's Tone Shop - Lemon Drop [traced]