Engineer´s Thumb - Compressor kit

Item number: 2084

Fantastic Compressor

Category: Modulation, Dynamic


starting from 28,00 €

Final price incl. VAT, plus shipping (mitttel)

Not available now!


The Engineer´s Thumb Compressor is designed by Merlin Blencowe (The Valve Wizard Website.

It features controls for Attack, Ratio, Threshold, Release and Level and works with a LM13700 IC, functional equal to the CA3080, which is also used in the Dynacomp.

This kit contains all parts you need to build a fully functional effect pedal.

Not included in the kit, but also very good to have:

  • Aluminium enclosure: select one above
  • DC power supply
  • 5 nice knobs for the pots, for 6,3mm shaft
  • Decal, transfer or transparent sheets for labeling

Here is the project page:
Engineers Thumb on The Valve Wizard

Instrument: Guitar
Effect-Type: Compressor

Build documents

Installation guide: Installation guide

Schematic and pcb: Schematic

Parts list (BOM): Parts list

Ratings (34)

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1 from 1 Customers found the following product review helpful
5 from 5 Fantastic Compressor

The best compressor Ive tried for electric guitar - smooth, silky compression that can be dialled up to high ratios with low noise. I installed a 300k lin pot for the release value resistor. At low settings it will distort in a very pleasureable way. I use this compressor for guitars, drum machines, basses etc and Im extremely happy about how it performs and sounds. Highly recommended!

., 28.11.2017
Total entries: 10
5 from 5 Excellent compresseur

Après deux montages DIY non satisfaisants, jai trouvé la perle : ce kit Engineers Thumb.

Tous les réglages sont possibles. Depuis une légère compression à peine audible jusquà une grosse compression.
Cette pédale est très transparente, elle modifie à peine le son de votre instrument.

., 13.07.2020
5 from 5 Very good

The quality of the pedal, after the first uses, seems unquestionable. An excellent compressor. Moreover, if ever someone who doesnt chew electronics well should read this review, my advice is, when soldering, to compare the codes of the various components illustrated in the diagram with those written on the board.
First the resistors, then the capacitors, then the integrated circuits, then the transistors, the potentiometers and finally the rest taking into account the general installation guide.
Have fun!

., 17.10.2020
5 from 5 Genious pedal

From Endless tones to simple rhytm compression. Just love it. Easy and useful build.

., 17.03.2021
5 from 5 Parfait

Première tentative dassembler une pédale mais pas de problème majeur, à vrai dire jai passé beaucoup plus de temps sur la peinture du boitier que sur le circuit... après correction de mes petites erreurs avec laide du forum, ça sonne - bien que je nai pas dautre compresseur sous la main pour comparer, mais à vrai dire je nen ressens pas le besoin. Signal clean, pas de bruit de fond.

., 17.04.2021
5 from 5 Excellent kit, excellent compressor

The Engineers Thumb kit is an excellent offering. High quality PCB and components, and if you order it with the pre-drilled enclosure it goes together like a breeze.
Merlin Blencowe (aka The Valve Wizard) is a highly respected engineer. I build a lot of vacuum tube gear and have referred to his published resources many times. The Engineers Thumb design is everything you want in a compressor. The included controls, lacking on some designs, allow you dial it in just right. Sounds great, highly recommended.

., 27.04.2021
5 from 5 Perfect compressor

Extremely tweakable compressor, can go from a suble, transparent compression to a squeezed mess, à la dynacomp.
I was expecting a little raise in the noise floor level, but to my surprise, its completely silent even at extreme settings.
Easy to build too

., 20.07.2021
5 from 5 Good noiseless compressor

Good noiseless compressor

., 27.09.2021
5 from 5 Excellent!

Excellent compressor, very quiet and effective.
You will notice you are using a compressor only when you desengage the your dry sound is thin and lifeless.
The most misunderstood effect ever; not an effect but a sound reinforcement.
The PCB is well made, components fits nicely; the box is well drilled.
An easy and pleasant build.
Thanks KLAUS

., 03.02.2022
5 from 5 easy build and great sound

you dont have to be an engineer to build this compressor, but its a fun build and the end result is superb. A lot of tweaking options to get desired sound and as others have mentioned - no additional noise.
This stays on my board

., 31.03.2022
5 from 5 Easy and fun to build

I had a lot of fun building this. Its easy enough for a beginner, and it sounds great. I would highly recommand this build !

., 22.04.2022
Total entries: 10

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