# Thumb Sucker



## Mike McLane (May 22, 2021)

Anybody had any experience with the Engineer's Thumb?  I'm thinking about a non-optical compressor (presummably a Ross derivative) and figured PPCB went with this schematic because it was a solid design, but it hasn't been out long enough to gather any Forum feedback.


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## Feral Feline (May 23, 2021)

@ficelles has built one. 



While it shares the same method as the overly ubiquitous Dyna-Ross & clones, the designer of the Engineer's Thumb touts how it is NOT a YAD-R, and supposedly fixes the inherent flaws of the D-R. 

A lot of bass players like the circuit, so I'll be building it, as the D-R and all its derivatives suck the low-end out of your bass signal. 


Other non-opticals non-DRivatives to consider: 
Orange Squeezer and variants (check out Toadworks Mr Squishy and G Tranter's Orange Smoothie),
Orman's AMZ Q&D (very cool, built in noise gate and does limiting too), 
Rothwell Love Squeeze (on my bench awaiting mods),
Jon Patton's FET-based BearHug,
That JAM on vero or PCB from UK.ELECTRONIC and Musikding, 
Schalltechnik_04 Pumpernickle (DBX 160-based),
Tadek Hexe,
GGG's Ibanez BP-10/CP-10 copy (cool, uses a BA6110 instead of the CA3080/13600/13700),
Wayne Kirkwood's TOKC (That One Knob Comp),
Pellucid by Jonny.Reckless...


Maybe this Oshpark project, too:  Audioleveler by W2AEW "https://oshpark.com/profiles/LRY/page/2" I haven't checked it out thoroughly yet, just stumbled across it and bookmarked it.


Good luck with your search, wherever it leads you.


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## ficelles (May 23, 2021)

I completed my Thumb Sucker build yesterday... having already built two other versions (FuzzDog, DeadEndFX) I noticed that this one is slightly different in terms of components and specific component values, and in operation seems to be a little more subtle although you can get extreme compression out of it if you want, it just dials in later. One improvement on the others is the Attack, which does seem to come right down to zero ms unlike my other two builds of the ET circuit. I'm certainly pleased with the Thumb Sucker and it's staying on my mostly-PedalPCB 125B board.


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## Feral Feline (May 23, 2021)

Man that board belongs in the "Show your Tidy Board" thread on TB! 

I like how the colours in the middle are book-ended by the hammer-tonish finishes.

Killer!


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## Mike McLane (May 26, 2021)

Anybody gotta line on how the RATIO control differs (or not) from a BLEND control?


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## Matopotato (Feb 6, 2022)

ficelles said:


> I completed my Thumb Sucker build yesterday... having already built two other versions (FuzzDog, DeadEndFX) I noticed that this one is slightly different in terms of components and specific component values, and in operation seems to be a little more subtle although you can get extreme compression out of it if you want, it just dials in later. One improvement on the others is the Attack, which does seem to come right down to zero ms unlike my other two builds of the ET circuit. I'm certainly pleased with the Thumb Sucker and it's staying on my mostly-PedalPCB 125B board.
> 
> View attachment 12084View attachment 12085View attachment 12086


Is the Attack quite subtle? Or did I miss some solderpoint…
First attempt and all knobs respond but for attack imho. Could be that it becomes more noticable once the others are ”aligned” more properly


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## princeofyams (Feb 6, 2022)

I’ve got one on the bench right now! Getting all excited hearing yours made it to the board. 👍


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## Matopotato (Feb 6, 2022)

Cool! Never had a compressor before so that was a great experience for me. The LED was not right over the drill template in my case. I guess 4-5mm north would have been better. So unless you have already drilled, check it first. I have a bigger type of Bezel though, but it bends alright in place. 
Haven't decided on art and layout yet, but I am leaning on something with a Atlas Copco Compressor, old 70s yellow type... We'll see. WIll be cool to learn how it goes for you 
Mine has a slight scrapy distortiony kind of side sound to it when ratio is high and threshold is low, especially humbuckers. I hope your's doesn't. Fingers crossed!


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## princeofyams (Feb 6, 2022)

That looks great man! I'm just on the board right now and still have to wait for the LM13700 in the mail. Thanks for the heads up though, I usually use 5mm LED's and in my experience the drill template always seems a few centimetres out of position. I've taken to just wiring them with connectors anyway, just incase I want it in a special spot on the enclosure. 

I'll let you know how it turns out, probably going to be a couple weeks before my order gets here though. Make sure you post when you get the art on there! Looking forward to seeing it.


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## Matopotato (Feb 11, 2022)

princeofyams said:


> That looks great man! I'm just on the board right now and still have to wait for the LM13700 in the mail. Thanks for the heads up though, I usually use 5mm LED's and in my experience the drill template always seems a few centimetres out of position. I've taken to just wiring them with connectors anyway, just incase I want it in a special spot on the enclosure.
> 
> I'll let you know how it turns out, probably going to be a couple weeks before my order gets here though. Make sure you post when you get the art on there! Looking forward to seeing it.


Any update on your progress? You get the LM13700 yet?
About LED position, it was just 5mm perhaps, not in the cm range, so not too bad, but annoying when I have to "dismount" and "re-mount" it.

In another thread I wrote about issues I have had with distortion. Seems I need to learn more how compression works and not just take each knob 0-100 without caring about the others. Also I learned that it can run on 18V as well (and thus 12V as well) which reduced the noise to a level where not much is disturbing anymore. I will add a socket on R10 to allow 1k (stock) or "1.8-2.2k" when on 18V after some tips.
It would be very interesting to learn if you have distortion in some extreme knob position of if it is my unit that is more grumpy.


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## princeofyams (Feb 11, 2022)

Matopotato said:


> Any update on your progress? You get the LM13700 yet?
> About LED position, it was just 5mm perhaps, not in the cm range, so not too bad, but annoying when I have to "dismount" and "re-mount" it.
> 
> In another thread I wrote about issues I have had with distortion. Seems I need to learn more how compression works and not just take each knob 0-100 without caring about the others. Also I learned that it can run on 18V as well (and thus 12V as well) which reduced the noise to a level where not much is disturbing anymore. I will add a socket on R10 to allow 1k (stock) or "1.8-2.2k" when on 18V after some tips.
> It would be very interesting to learn if you have distortion in some extreme knob position of if it is my unit that is more grumpy.


Haha! Not yet, LM13700's are on route should be here sometime next week. 

That is very interesting! Can you link the thread? I might just build mine for 12V or 18V if that's the case. I assume it would be better if the capacitors were rated higher though, right?


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## princeofyams (Feb 11, 2022)

Never mind I found it!


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## Matopotato (Feb 11, 2022)

princeofyams said:


> Haha! Not yet, LM13700's are on route should be here sometime next week.
> 
> That is very interesting! Can you link the thread? I might just build mine for 12V or 18V if that's the case. I assume it would be better if the capacitors were rated higher though, right?


I got my kit from Das Musikding, and I checked the caps, ICs, transistor etc and they all have margin. So just read yours. If you are above 12 then you can try, or above 18...
Only advice to consider is in other thread about R10.
I'll put in a socket so I can try around.
Will check 12V later on.


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## princeofyams (Feb 11, 2022)

Matopotato said:


> I got my kit from Das Musikding, and I checked the caps, ICs, transistor etc and they all have margin. So just read yours. If you are above 12 then you can try, or above 18...
> Only advice to consider is in other thread about R10.
> I'll put in a socket so I can try around.
> Will check 12V later on.


Yeah I saw the thread. I'm going to wait to populate when I see what you do.


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## Matopotato (Feb 11, 2022)

princeofyams said:


> Yeah I saw the thread. I'm going to wait to populate when I see what you do.


Just check through what markings your components have. Then you know your options


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## Matopotato (Feb 11, 2022)

What component is lowest rated?
(LM13700 should be well within margin)


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## princeofyams (Feb 11, 2022)

Matopotato said:


> Just check through what markings your components have. Then you know your options





Matopotato said:


> What component is lowest rated?
> (LM13700 should be well within margin)


I've got plenty of extra caps rated well over the 30V. I always buy extra and have done a few builds with charge pump for 60-100V rated components. 

I just wanted to see how you thought yours worked best before I start populating at all.


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## Matopotato (Feb 11, 2022)

I am no genius at this. I am a happy amateur at best... 
So I checked mine and from some previous experience I fell that if they all check out above 18V, I am willing to try. I also asked and felt I got the OK. How much, if any, the R10 1k vs 2.2k affects the sound? No idea, but adding a socket and having the option is an easy enough choice. As long as I can get the 1k out without any problems. (De-soldering is worse than soldering IMHO. But dismantling a TV set helps bring you up to speed. Adds some vintage components to your collection...)
Resistors at 1/4 W I don't worry so much about. Heat at the most.
The caps need to check out, and ICs can be varying unexpectedly. Transistors are also worth getting datasheet readings of.
All that said, if you still try, missed a thing, you will probably fry at the most one or two components. Unless they are golden, yo could find new ones. I believe experience is the enricher.
Anyway, it will be you choice. But if all components check out, then I wouldn't worry. But I once was close at getting a replacement IC type of component until I read up on its max voltage. And at 9.0V I preferred to wait up for the 12V option. I think you get the idea. Experiment, but with control.
I did some recordings with SC and Humbucker for 18v 12v and 9v  ( I really like my Truetone C6 and C12 power supplies) I will post in the other thread now that you found it.
My own impression though: 9-12-18 feels sort of linear. 18V less distortion problems, so I will go with that and postpone buying any "market" version of compressor, although I will not rule it out. 
I honestly built this to be able to discard compressors as "nah, tried it, didn't like it" but was actually blown away with the fattened sound my Single Coils came out with. I was obviously pushing the build a bit, and I just don't do "subtle" very well (not really a musician, just hobby). But I was pleasantly surprised over the effect. Not how it came out of the speaker as much as how it felt in my hands...
So check the other thread for some simple amateur samples of 9-12-18 SC vs Hum.


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## micmac (Dec 31, 2022)

Hi all,

I boxed up a Thumb Sucker yesterday. Easy build, didn't take too long, no problems. It's low noise. The bright switch difference is subtle, but when I turn it off I miss it immediately  All knobs work. With the release knob it is a bit hard to tell. But I found that when it's CCW and I strike a note and then silence the guitar the little background noise there is becomes audible again quickly. The more I turn the Release knob CW the longer it takes for the background noise to become audible again.

I never used a compressor before (well, a friend lent me a one over a weekend once and I don't have any memorable recollection of it). But playing guitar cleans into this is great. I never knew I needed a compressor  With dirt I didn't try yet, but I'm guessing I might be in for another surprise.

I used a Musikding kit for this. I only deviated from the kit with C5 and C6. I used 1uF Tantalums for them instead of the aluminum electrolytic caps that came with the kit. I tried to put films (the boxy things, like MKT) but there wasn't enough room in my opinion.

I marked the 2 knob version defaults on the decal. So Attack fully CCW, Threshold fully CW and Release where the pot has 370k between lugs 1 and 2. So right now I leave these knobs like that and only change Level and Ratio to my liking and it sounds great. I thought that makes sense for somebody who never used a compressor before.


Anyway, nice PCB PedalPCB team! Thanks for making this stuff accessible to the masses!

Kind regards,
Seb


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## PunchySunshine (Jan 7, 2023)

micmac said:


> I never knew I needed a compressor


This was the first pedal I built from PedalPCB.  It's always on now.


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