All posts by guitar poppa

About guitar poppa

Former product design teacher, now on retirement and still post war blues guitarist, i've been found of electronics since I was 14... The guitar poppa web site is the way to make known and spread my experience in transistor and tube vintage electronics


FullBender1 is inspired by the Tone Bender® Mk1,
an historic fuzz designed in 1965 by Gary Hurst.
It was not many distributed, being ahead of fashion, and too quickly forgotten in favor of later models from Tone Bend

One finally rediscovered it during the vintage fashion of the 90s, et reevaluated because it offered a hairy and dense fuzzy sound, with nice dynamic gate effects…

FullBender1 by

The first prototype of the FullBender1 which was still called SoftBender1.

Continue reading FullBender1


Lil’HarpZone was initially motivated by a custom order…
It is now available to everyone !

Lil’HarpZone is a low sized transposition to harp of the famous Metal Zone distortion pedal.
It takes back most of its saturating circuit and features a specially designed One Knob Tone control.

Lil'Harzonz par, adaptation de la disto MetalZone à l'harmoLil’HarpZone, and its simple controls.

Continue reading Lil’HarpZone


HarpZone is a distortion stompbox made for Harp.
It takes up the structure of the classic Metal Zone®,
and preserves the original grit, but adapts it
to the particular sonic profile of the harmonica.
It also features a booster to take fleshy choruses.

HarpZone, distorsion spéciale pour harmonica, avec 2e switch de boost

HarpZone, distorsion spéciale pour hamonica, avec booster

Custom prototype for the french harp player Marko Balland, 2019.

Continue reading HarpZone


Custom : An old-school amp head, but with lots of options…GuitarPoppa, ampli 15W Custom
La reprise…

A musician’s order based on the 1963 AC15 pentode channel, with lots of options…
Getting the Covid, I had to stop manufacturing during the spring and summer of 2021.
Here it is finally finished, with gain control and presets, a complete tonestack, an effects loop and a speaker attenuator…
My amps 10 to 25W

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Project  : An echo box that saturates like Little Walter used to do…actuality : project to come
Get the joyful grit of the Chicago Southside harps !

Little Walter’s echo is like the reverb of punk-surf groups: it is as much a matter of timbre and sound texture as of pure delay. So I thought to add a SpanishMoss overdrive to the echo to get back that special sound… I’ll tell you what it’s going to be !…
Contact me for more information…

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 Custom actuality : An old-fashioned amp head, with plenty of optionsguitar poppa's actuality : a project to come
A development of the Vox AC15…

Initially, a musician’s command based on the original AC15, with lots of options:
A 3-band tone, a booster, a line output with HP simulation, an attenuator …
And all built old-fashioned way on a turrets card (except for the effect loop).
My amps 10 to 25W

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Project : a Di-Box that make your sound before injecting it into the PA.SimSymBox : boîte de direct qui met en valeur la couleur et le grain de l'instrument
To be sure of the sound quality you will send to the sound system of the bar …

Imagine an instrument preamp with adjustable tone and overdrive …
Add a speaker simulator, and a balanced output to the mixer …
You have everything you need to get your sound and send it directly to the sound system!
Contact me for more info and custom realization…

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New : preamps for harp with solo Boost and balanced output to PA.preamps for harp with solo Boost and balanced output to PA
What it takes to be independent on small stages

Initially, an order from harmonica player Vincent Bucher … He wanted a CurvyMama preamp followed by a speaker simulator and a balanced output to the PA …
And also with a chorus push button, and an output for stage amp (if necessary) …
The “CurvyMama SimSym” product page

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New : a 3W microCombo with 13cm speaker
3W microCombo with 13cm speaker
The MicroCombo range now has a big brother

A greedy sound for the guitar or the harp in a beautiful solid walnut box.
The watts are real, as well in clean sound as in light crunch or in total saturation.
Speaker on your choice: Celestion, Sica or Jensen, depending on the desired sound color.
MicroCombo 3W product page

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News from the workshop: pedal modifications
pedal modifications by Guitar Poppa
Gain and roundness improved in a Fuzz Face Lift from Big Knob.

It is a Californian artisanal stompbox, which updates the Tone Bender II Professional with a silicon buffer and a fuzz circuit equipped with Russian germanium MP39A.
I bring more body, a better polarized buffer, progressive gain pot, adjustable bias …
Modifications and customizations by GuitarPoppa

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Custom : a 25W Silicium / Germanium hybrid amp head
25W Silicium / Germanium hybrid amp head
SweetGerm +25W

Association of the SweetGerm preamp and a 25W hybrid PowerAmp.
Germanium brings its color and the grain of overdrive, silicon improves reliability.
Customizable connections: lines, loop, phones etc …
Facebook review from the first client behind the project

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Now available:
CurvyMama, a fleshy overdrive that moves like a round lady !

A preamp-overdrive designed for juicy guitars and harmonicas.
Single pedal or large format, with speaker simulator and XLR3 symetrical output. Interactive and nuanced Contour and Bite settings… And a special germanium grit !
CurvyMama’s product page

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Custom : Pedal duos in a single box
Duos pédales - The Scream + VintageBoo
The [S]cream + VintageBoo

Initially, custom orders from friends … We have selected complementary pedal duos … With an additional economy of scale: a duo is less expensive than the two pedals that it brings together, because some circuits do not need to be repeated.
Contact us to discuss your desires and projects…

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First Germanium Micro-combos from 1W to 3W RMS
Germanium Micro-combos, from 1W to 3W RMS
On the workbench…

These will be two Micro-Combos for harmonica or guitar, respectively 1W and 3W…
The electronics are traditional, without integrated circuits. All germanium power amplifier and selected NOS speaker : The clear or overdriven sound will be lively, warm and rich!
MicroCombo1W product page MicroCombo3W product page

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A speaker attenuator with line output and bypassspeaker attenuator with line output and bypass
CoolCrunch fits in a box to be placed in the bottom of combos …

Realization on request of a harp friend for his Champ 57 reissue …
Two models, dedicated to 5W or 30W power amplifiers.
Continuous volume adjustment, byPass switch and line output always available…
CoolCrunch5 and CoolCrunch30 product page.

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Guitar Poppa likes to repair or update vintage ampsGuitar Poppa likes to repair or update vintage amps
Review and restoration of a french amp from 56/65 …

Renowned French brand: Stimer amplified the great Django, then the first french rockers …
I can repair or transform these old amps with all due respect.
But only small models, less than 25W: my workshop is very small!
(and international transport is so expensive!)

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Pedal mods
GuitarPoppa, modifications, customisations, performances, ergonomie, usages spéciaux
Technical and ergonomic improvements; adaptation to personal uses.

Recently I adapted a [good] copy of TS9® for bass …
At the moment, I am modifying a Metal Zone® for the harmonica …
If your pedal is correctly designed and manufactured, we can customize it to your wishes!
Modifications and customizations by Guitar Poppa

My Amps : 10 to 25 Watts

I make amplifiers for guitar or harmonica … Small, just like my workbench !
They are available as separate head …
The layout and the equipment are to be composed “custom” according to your project.

Transistor models feature a real power of 10 or 25W on 8 ohms.
They use a 60s germanium technology, which denies the bad reputation of transistors…
It brings especially a natural compression and a progressive transition to overdrive which have little to envy tubes, with a price also compressed!

I also realize high quality tube models, custom 5 to 15W, with vintage or high-end components where it’s worth and audible.

In both cases my aim is to offer amplifiers intended for home use or small concert venues, without technical weakness, and with a sound that will please the instruments.

Continue reading My Amps : 10 to 25 Watts

My stompboxes : DD size

I have designed some large format stompboxes (approximately 20 x 11 x 3.5cm), either because they have to contain a printed board of significant dimensions, or because they have to bring together several cards.

These configurations are often the result of custom orders by musicians with strong choices … Their requests have led me to design typical equipment, which are often associations of existing circuits.
Everyone can now benefit from these experiences, or imagine their own project!

Continue reading My stompboxes : DD size

Samples : LikeYourFace Fuzz

LikeYourFace - logo produit L15x300dpi

Classic smooth option

Big basic Fuzz and heavy riffs, in the manner of the sixties..
Strato-like guitar.
LikeYourFace with Fat preset ; Fuzz @ 15:00 (more is possible ; Tone @ 12:00 (neutral).
Wild thing (neck pickup) : then Shape of things (bridge pickup).

Fuzz used as a light overdrive : Bright Strato blues
Strato-like guitar.
Neck pickup and Bridge pickup mixed.
Fat Preset ; Fuzz @ 10:00 to get a smooth texture ; Tone @ 13h to get more harmonics.

Classic bright option

A scratching sound, with open strings and a bit boosted medium
Archtop Guild X160,bridge pickup at first, the  mixed pickups at the end.
LikeYourFace basic, Classic bright option. Fuzz @ 15:00. No preset nor tone.
In-A-Dadda etc. (micro manche)

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Recording conditions

Bandeau - Enregistrement - Samples-BirdMaster

2xEL84 amplifier from 1967, restored by me. Clean canal, tone control almost flat.
10″ speaker, Weber F10-150T (recommended for Fender Princeton) ; bass reflex cab.
Shure SM57, placed like in the pic above.
A bit of Holly Grail® reverberation, just for pleasure.

Strato-like guitar from the 80s, rather cheap but equiped with Rio Grande texan pickups.
Archtop Guild X160 from 1988.

Bandeau fin gris moyen - Samples


MicroCombo 3W is a portable and powerful micro-amp for guitar or harmonica.
The all Germanium power amp, the big brand speaker  give to it efficiency and musicality.
It will let you play at home or in small places, connected to an external cabinet or to the sound system of the bar.
Options are available when ordering.

MicroCombo 3W, ampli 3W pour guitare et harmonica - amplification au germanium

MicroCombo3W in its walnut enclosure.

Continue reading MicroCombo3W

My MicroCombos

My MicroCombos are small amps of real power 1W and 3W.
They are designed old-fashioned way, from a technological point of view as well as from a design point of view.

Electronics in through-hole components from the 60s-90s ,
100% germanium class AB power amplification.
Branded, contemporary or NOS loudspeakers.
Reinforced solid wood case (European walnut and plywood) and original Fender canvas.

Their clean sound is mild, and they crunch at low level without sounding harsh, with a roundness that has nothing to regret from tubes.
They are well suited to rehearsals at home, or to small parties!
They were originally designed for the guitar, but I quickly grasped the interest of working just as much for harmonica, taking advantage of the sonic grain of the old transistors…

Continue reading My MicroCombos

Germanium transistors for Fuzz – 4

Switching transistors
ex : 2N404 (the american classic)

The first transistorized circuits for automation and computing required specific components that were straightforward in their response but without extreme bandwidth. Rather close to radio frequency transistors, they are distinguished by their reliability and deliberately moderate maximum frequency. Some models may produce a vintage sound grain, suitable for Fuzz Face. They could make as much reference as the ubiquitous small power audio transistors : American do-it-yourselfers have not been mistaken, and have since a long time embraced the classic 2N404 …

Continue reading Germanium transistors for Fuzz – 4


CoolCrunch is made to attenuate the volume on the speakers without lowering the master volume of the amp …
One keep then the crunch without breaking the ears …
Due to its small size and simplicity, it fits inside the combos and in your budget.

CoolCrunch 5 et 30. Atténuateurs HP pour amplis à tubes de 5 et 30W

Guitarpoppa - Atténuateur CoolCrunch30CoolCrunch30, model 2023,
with its connection cord to the amp and a jack socket to the speaker.

Continue reading CoolCrunch


LowVoltTube is an original pedal that combines two references of the guitar sound :
— A preamp-overdrive, TS9 type, with its tone control …
— A tube stage included to generate a real “tuby” grain.

The tube is a 50s NOS model, specially designed to work directly with automobiles batteries.
Boutique quality, but for a moderate price !

LowVoltTube preamp/overdrive - Logo

LowVoltTube. Préamp/overdrive with JRC4558 and NOS tube 6ET6 (EF98)

LowVoltTube — First issue, 2018.

Continue reading LowVoltTube

Germanium transistors for fuzz -3

High Frequency Transistors
ex : OC44 (Rangemaster, 1966)

High frequency germanium transistors have appeared as a second generation. Their elaborate technology made it possible to obtain a consequent gain even at radio frequencies : 30MHz, then 100MHz or more.
More expensive, and fragile at the beginnings, they have not been much used by pedal manufacturers, before all concerned by economy and robustness.

The OC44 was however exploited by Arbiter in the first Treble Booster, the Rangemaster, where its gain and bandwidth yet modest worked perfectly.
With the contemporary recoil, we rediscover the quality of these transistors, the fineness of their sonic grain, and their real interest in designing modern boosters and fuzz …

Continue reading Germanium transistors for fuzz -3

Germanium transistors for Fuzz -2

Audio preamplification transistors
ex : NKT275 (Fuzz Face, 1966-67)

These are the most common germanium transistors. They were designed for audio pre-amplification circuits in consumer and mid-range equipment, where they quickly replaced the tubes. They are distinguished by a gain which can reach 200, and a maximum frequency of about 1MHz.

Pedals made in 1966-68 first operated with black glass models like OC75 and then encapsulated glass like OC76 and OC81 … As the AC125 and AC126 by Philips / Mullard were a bit expensive, cheap versions like the NKT275, and some SFTxxx had their hour of glory before being forgotten, then rediscovered around 1990 …

Continue reading Germanium transistors for Fuzz -2

Germanium transistors for fuzz -1

Output audio transistors
ex : AC128 (Fuzz Face, 1966-69)

These transistors were at first designed to drive the loudspeakers of radios and consumer audio products. They are distinct from other families by their dissipable power and their maximum collector current.
In 1967, some models have been known as bringing a so called “creamy” sound texture to Fuzzboxes. Therefore, they gained a reputation that made this family of components enter the guitar effects culture.

Continue reading Germanium transistors for fuzz -1

Stompboxes, 1590BB size

Guitarpoppa : pédales

My activity is to design and handcraft stompboxes, preamps or small amps.
It feeds on my experience as a musician and technician trained in the 60s.
Some of my pedals perpetuate the tradition, with updated means.
Others have an original design.

They are built in the international 1590BB format, approximately 12 x 9 x 3cm.
This size is no longer fashionable but is justifiable : My pedals use traditional components manually welded and not micro-components assembled by robots. The wider printed tracks and pads are more sturdy, and desolderable, therefore repairable without risk of takeoff… Same for potentiometers…
On an other hand, my circuits are more provided than most of stingy circuits in ordinary productions : active filtering in the supply line, really playable presets, pull down components minimizing switching noises…

Traditional stompboxes

I reproduce the historical circuits in the love of their sound …
And I perfect with all respect what is worth it.

Improvements by Guitar Poppa :

• Technicity : verified and corrected schematics, sorted components, neat powering.
• Functionality : Well balanced impedance, progressive settings, raised output level.
• Musical potential : refined tone and grain, dynamic response to instrumental playing.
• Customization : custom features and settings, duets coupled in a single box…

4 classics

The (S)cream - overdrive de type TS9 amélioré - réglage de textureThe (S)cream

TS9 type Overdrive
with a diversified sonic texture.

Germanium Fuzz ,
of the Fuzz Face.

Germanium Fuzz ,
development of the ToneBender Mk1.

Clean booster,
of the Rangemaster


Original preamps and overdrives

The identity of a pedal lies in its sound color and grain, as well as its dynamics…
…It will combine these parameters in musical quality,
and finally its behavior must “please” the instruments that are connected to it…

3 originals

LowVoltTube by, preamp/overdrive with a NOS low voltage tubeLowVoltTube
with a NOS low voltage
tube inside.

CurvyMama, préampli pour harmonica et guitare. Donne du corps et du grain au sonCurvyMama
with a warm and fleshy tone for harp or guitar.

SweetGerm by, a germanium preamp to make your instrument singSweetGerm
Germanium preamp
to make guitar
or bass sing

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On this website

See also my “Products” page

Go to the following : “Mods and Customization”

Go and read Terms of Sales (in french)


Go and see Guitar Poppa’s Facebook page

Samples : The (S)cream overdrive

Samples.The (S)cream - Bandeau de titre L15

The 3 presets : classic (=TS9®) ; clear ; deep

3 bluesy improvisations , using each of the 3 presets…
Low drive @ 9:00 — Consecutive presets : classiccleardeep.
Strat-like guitar, neck pickup.

Samples. The Scream. Bandeau fin gris moyen - L15

Texture according to the drive setting

Two different drive settings, harmonies in D …
Classic preset — Consecuting settings : low drive @ 9:00 / mid drive @12:00 / low drive @ 9:00
Strat-like guitar, bridge pickup.

Two different drive settings, on Next time you see me…
Deep preset — Consecuting settings : low drive @ 9:00 / mid drive @12:00
Strat-like guitar, neck pickup.

Two different drive settings, playing rhythm patterns in F sharp minor …
Deep preset — Consecuting settings : low drive @ 9:00 / mid drive up to 12:00
Strat-like guitar, bridge pickup.

Samples. The Scream. Bandeau fin gris moyen - L15

Texture according to the diode mixing

4 different mixings, silicon diodes + LEDs, playing a slow theme …
Successively :  1 : Leds 100%  /  2 : Leds 50% + silicon   /  3 : Leds 25% + silicon  /  4 : Silicon 100%.
Deep preset — Drive up to 1h:00.
SG-type guitar, mixed pickups.

Samples. The Scream. Bandeau fin gris moyen - L15
Recording the samples

Samples : The Scream. Bandeau - Enregistrement avec Stato

• The (S)cream is JTC4558 equipped.
• Diodes :  100% silicon on the first four samples ; leds + silicon on the last.

• 2xEL84 amp from1967, fixed by me. Clean canal, light mid notch @ 500Hz
10″ Weber F10-150T speaker, bass reflex boxed.
Recorded with a SM57 close to the speaker, between dome and edge.
A bit of Holly Grail® reverb…