Cheap DIY Distortion and Compressor and Fuzz kits

[Marcel]

Back to the compressor pedal...

Things are best tackled with a fresh mind on a new day is so true here. Took maybe 5 minutes for me to find the wiring error of having the tip and ring connections on the input jack swapped. A penalty for working in evening daylight I suppose.

Once the error was corrected the pedal was tested and on the audio quality front it passed admirably, but as a compressor ... Hmmm, maybe I'm a bit spoilt from previous experience with 'real' compressors as to my ears this little pedal was somewhat disappointing. After some messing around I worked out the variable gain section that is subject to the amount of light on the LDR worked quite well, however the LED and drive signal to the LED was far less than stellar. I swapped LED's with spares I have, changed to different coloured LED's, all with little tangible improvement. I concluded that maybe a high intensity LED is what is needed which halted work as I have none on hand.

In the photo you can see beside the IC the black sleeve I used between the LDR (Light Dependant Resistor) and the LED. Even with this arrangement the simple act of taking the back cover off the pedal housing has the effect of slightly reducing the gain through the device, enough change to be easily heard when listening to a strummed guitar and through a small practice amp, so limiting stray light into the LDR is important to the overall performance of the pedal.

[Simon Barden]

Have you got anything white or silver that you can use instead of the black tubing? You'll get a lot more reflected light, effectively making the LED brighter. You can always run some black tape round the outside to stop external light ingress.

[JohnH]

Glad you got it working. I guess at the price it's not all that surprising it's not the best compressor, but it's an interesting exercise nonetheless

[Marcel]

It has been interesting JohnH, and to a fair extent quite enjoyable, and the fun isn't over yet...

About the only thing I can think of Simon that could improve the little light tunnel is maybe a small block of Aluminium with a 5mm hole drilled through. Using Al-foil could be risky in creating short circuits, and anything heavier risks damaging the legs of the LED or LDR. I do have some self-amalgamating tape that I could wrap around, but I think the biggest issue is getting the LED set right to have the greatest affect on the LDR. By my reckoning there needs to be a brighter LED so it's either a new and brighter LED or changing the current limit resistor to a lower value so that the existing LED burns brighter. It would be nice to have a circuit included with the kit so the choice of which way to go would be simpler. Look like I'm going to have to trace the whole thing out the hard way...

[DrNomis_44]

It has been interesting JohnH, and to a fair extent quite enjoyable, and the fun isn't over yet...

About the only thing I can think of Simon that could improve the little light tunnel is maybe a small block of Aluminium with a 5mm hole drilled through. Using Al-foil could be risky in creating short circuits, and anything heavier risks damaging the legs of the LED or LDR. I do have some self-amalgamating tape that I could wrap around, but I think the biggest issue is getting the LED set right to have the greatest affect on the LDR. By my reckoning there needs to be a brighter LED so it's either a new and brighter LED or changing the current limit resistor to a lower value so that the existing LED burns brighter. It would be nice to have a circuit included with the kit so the choice of which way to go would be simpler. Look like I'm going to have to trace the whole thing out the hard way...

I seem to remember reading somewhere that most LDRs (Light Dependent Resistors) tend to have a bell-shaped light-sensitivity curve where they are most sensitive to green light, so, maybe using a Green Led might help things.

[Marcel]

Yeah Doc, the kit came with a Green LED and out of all the LED's I've tried the Green does work the best. It just isn't bright enough to appreciably affect the LDR, and the LED certainly affects it less than stray daylight does which should give an idea of the depth of the problem.

I've had the thought that if I replace the LED's current limit resistor with a pot it might work as a kind of threshold control.

[DrNomis_44]

Yeah Doc, the kit came with a Green LED and out of all the LED's I've tried the Green does work the best. It just isn't bright enough to appreciably affect the LDR, and the LED certainly affects it less than stray daylight does which should give an idea of the depth of the problem.

I've had the thought that if I replace the LED's current limit resistor with a pot it might work as a kind of threshold control.

I think most standard Leds will work fine with up to about 20mA of supply current.

[Marcel]

I found the resistor in the compressor pedal that set the current through the LED. It was a 4k7 so max current was about 1.9mA. Changing it to a 1k or 10mA effected nil change in performance, and annoyingly the most dramatic change in gain was still only when I fitted or removed the back cover. Actually depending on the gap or space between the cover and the housing I could vary the volume to various levels so the level control portion of the compressor works very well, just the level detection and LED driver section is useless.

After spending a few quality Sunday hours on this compressor thing and trying a number of alternate value components I've restored it to original and decided to set it aside. It works, but not as well as could be expected. Some mid winter R&D and subsequent modification is needed to turn it into something I think is useful...

[Marcel]

The Fuzz Face kit... Not what I was expecting....

When I first assembled the kit the result was disappointing. There was some Fuzz, however there was also a lot more of spluttering and extended patches of unwanted silence. The fuzz itself was consistent in tone and level just it wasn't consistently there, almost as if I had a loose wire or something. At first I suspected that I had cooked the transistors when I soldered them in. Sadly Germanium transistors can be 'cooked' a lot more easily than their Silicon counterparts. So after downloading data sheets of the supplied Germaium AC128 transistors and getting out my stock of Silicon PNP replacements, I set about to find the real cause of the disappointment to this so far less than impressive build.

I hooked up my little LCD Cro and a signal generator and pushed a clean sine wave through it to see visually what was happening to the signals. On the test bench with signals of 50mV and above it worked "fine", and instantly I realised that there in lay the problem, and that I hadn't cooked the Germaniums. Normal signals from a guitar are not usually that big. What this Fuzz pedal really needs is some clean boost. At the same time I also noticed an induced common mode hum on the screen when I touched the pedals metal housing which indicated the housing wasn't earthed, so I replaced the output jack with a different type which cleared that problem.

I patched in the compressor kit pedal before the Fuzz... Success!.. And it sounds quite okay. Not too harsh, Has musical aspects to notes/chords played through it. Interestingly and despite its short comings the compressor kit pedal seems well suited to drive the Fuzz Face kit pedal as a good range of tones can be dialled up using both together... Note to self - always use a pre drive or level boost pedal with this Fuzz Face kit pedal.

One thing I needed to get used to is the Fuzz pedal does mute when volumes from the guitar get a bit low which can be useful in some scenarios but also can get very annoying. Keep the strings moving and you get consistent noise from the amp, let notes ring out and they will Fuzz until they suddenly (but predictably) die.

So I got all 3 kit pedals working. None are as good as any commercially made pedal but certainly good enough to make practice noises at home. All 3 sound different to commercially made units which if I was chasing tone of another guitarist would make most of them a big fat fail, however if they were in use by a guitarist/writer they do offer(force) options in tone that would push certain writing styles. Of the 3 kits I favour the distortion kit pedal with the picture of the Dragon as it has the best range of sounds that I like, with the Fuzz in at 2nd and the compressor 3rd as it gave the most disappointing result.

For those who are interested, On my home 'just for fun' setup I typically run 7 pedals, For the moment the reverb pedal from earlier in this thread has displaced my Nux Time Core as my 2nd delay pedal, and of all things the Dragon Distortion kit has displaced my TS9. Other pedals in my line up between my usual LP (and increasingly the ES-1TL) to the JVM210 are a Dunlop JH-1 Wah, a PolyTune 3, a TC Electronics Sub-n-up, a Joyo Vintage Phase and a CatalineBread Echorec. ... Go figure...

[DrNomis_44]

The Fuzz Face kit... Not what I was expecting....

When I first assembled the kit the result was disappointing. There was some Fuzz, however there was also a lot more of spluttering and extended patches of unwanted silence. The fuzz itself was consistent in tone and level just it wasn't consistently there, almost as if I had a loose wire or something. At first I suspected that I had cooked the transistors when I soldered them in. Sadly Germanium transistors can be 'cooked' a lot more easily than their Silicon counterparts. So after downloading data sheets of the supplied Germaium AC128 transistors and getting out my stock of Silicon PNP replacements, I set about to find the real cause of the disappointment to this so far less than impressive build.

I hooked up my little LCD Cro and a signal generator and pushed a clean sine wave through it to see visually what was happening to the signals. On the test bench with signals of 50mV and above it worked "fine", and instantly I realised that there in lay the problem, and that I hadn't cooked the Germaniums. Normal signals from a guitar are not usually that big. What this Fuzz pedal really needs is some clean boost. At the same time I also noticed an induced common mode hum on the screen when I touched the pedals metal housing which indicated the housing wasn't earthed, so I replaced the output jack with a different type which cleared that problem.

I patched in the compressor kit pedal before the Fuzz... Success!.. And it sounds quite okay. Not too harsh, Has musical aspects to notes/chords played through it. Interestingly and despite its short comings the compressor kit pedal seems well suited to drive the Fuzz Face kit pedal as a good range of tones can be dialled up using both together... Note to self - always use a pre drive or level boost pedal with this Fuzz Face kit pedal.

One thing I needed to get used to is the Fuzz pedal does mute when volumes from the guitar get a bit low which can be useful in some scenarios but also can get very annoying. Keep the strings moving and you get consistent noise from the amp, let notes ring out and they will Fuzz until they suddenly (but predictably) die.

So I got all 3 kit pedals working. None are as good as any commercially made pedal but certainly good enough to make practice noises at home. All 3 sound different to commercially made units which if I was chasing tone of another guitarist would make most of them a big fat fail, however if they were in use by a guitarist/writer they do offer(force) options in tone that would push certain writing styles. Of the 3 kits I favour the distortion kit pedal with the picture of the Dragon as it has the best range of sounds that I like, with the Fuzz in at 2nd and the compressor 3rd as it gave the most disappointing result.

For those who are interested, On my home 'just for fun' setup I typically run 7 pedals, For the moment the reverb pedal from earlier in this thread has displaced my Nux Time Core as my 2nd delay pedal, and of all things the Dragon Distortion kit has displaced my TS9. Other pedals in my line up between my usual LP (and increasingly the ES-1TL) to the JVM210 are a Dunlop JH-1 Wah, a PolyTune 3, a TC Electronics Sub-n-up, a Joyo Vintage Phase and a CatalineBread Echorec. ... Go figure...

Sounds like the Fuzz Face you built may be biased wrongly, what voltages are measuring on the transistors?, you should see about .6V on the collector of the first transistor and around 6V on the collector of the second transistor, if they are biased about right, you should see something like .2 to .3V across each transistor's B-E junction, I could measure the voltages in my Jim Dunlop JD-F2 Fuzz Face and post them as a reference if you like, the JD-F2 uses two AC158 Germanium transistors.