Archive for January, 2014

Sweet Peach Fuzz

After playing around with it for awhile, I’ve got some ideas for improvements and what-not:

  1. RV1 or R1 could be changed.  Below 9:00 on the pot, it stops amplifying.  Raising R1 or lowering RV2 would enable a slightly different taper that would not be turned off.
  2. A limiting resistor needs to be added between lug 3 of RV1 and the negative input to keep it from turning off.  It could be approximately the same value as R1.
  3. The diodes could be moved for a different texture.  If they were parallel to ground, either before or after stage 2, it would have hard clipping.  Adding it to Stage 1’s feedback would offer control over the amount of distortion.  Putting a pot in series with stage 2’s output and having the diodes cross from lug 3 to lug 1 would offer soft clipping with a control.
  4. That tone control is awesome.  I saw it at muzique and had to try it.  I’m glad I did.

The settings I like best as of now are: Frequency – 12:00, Tone – 3:00, and Volume 3:00.

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Sweet Peach Fuzz (or Big Black Box)

Posted: January 27, 2014 in Effects

I built a modified version of a Muff Fuzz with a TL072.  It has a germanium diode and LED on one side of the clip and two silicon diodes on the other side.  I added a tone control and a gain control to it and changed some values from the original.

As is is an inverting amplifier, it can have a gain of less than 1.  When the gain control is turned down past 9 o’clock, the gain is too low to amplify.  Low gain settings sputter/stutter and it’s kind of cool as an effect.

Unfortunately, the foot switch I had was non-functional, so it’s hardwired as of now.  It’s still pretty cool.  Here’s a simplified schematic:

Image

Here’s the original.

 

(Update)  The 470k bias resistors should have included a small cap to ground.  A 10pf would work with this, or you could make the resistors lower and use a slightly higher cap (100k and 68pf-100pf would set the frequency high enough for the harmonics to not be interfered with).

The omission of the cap makes the distortion crap out when the signal voltage drops below the bias voltage.  It’s cool for a gated effect, but not for a smooth, sustaining sound.  A variable cap would be cool for adding a gate control.

EMG Fuzzstortion Update

Posted: January 26, 2014 in Uncategorized

I received some 1n34 germanium diodes and put one in parallel with a silicon diode and a 250pf capacitor on the mix control.  I love it.  The addition of germanium and a cap makes it less harsh, clips easier, and gives the asymmetrical clipping without having to bump the forward voltage up.

You can still clip with heavy picking when the mix control is turned all the way down, but it does provide more headroom.  The lower clipping threshold on the germanium makes the volume difference between 100% and 0% more noticeable.  The cap is less effective as the clean signal is mixed in, so it seems like a very slight treble boost.

http://www.youtube.com/user/aliensoulleech/videos

I have some demos on there and a few personal things.  Just to let you know: if I miss a note, biff a riff, or otherwise do not perform perfectly, I don’t do a retake and I don’t really give a shit.  It is what it is and the demonstrations are about the sounds, not how awesome I am.

I have some videos to make for the EMG fuzzstortion mod, the split humbucker mod I did on one guitar, and the combo of a 5-way switch and spin-a-split mod on another.  My shoulder is jacked up.  Once it heals, I’ll be making more awesomely bad videos.

The pdf opens in this window.  Open it in another tab if you want to see it and follow along.

Table Dancing Double Multiplier Warmonger

This is an approximation for the preamp of an amp I love.  It has multiple channels, wazoos, doo-dads, and what-nots.  This is a bit different from the original.  It’s only one channel.  I moved a couple grid stop resistors to attenuate with the grid leak resistors.  Their values are different than the original, but are scaled to do the same functions.  I changed the value of parts of it to reduce noise, but have approximately the same frequency and performance responses in most cases.  I changed some of the cathode resistors to a more common value, but it’s close to tolerances and barely shifts it into a colder bias that makes little difference.  Some of these changes are also because it doesn’t need to have all the extra stuff in the overall circuit if it’s only one channel.

This is NOT an exact clone.  I think of it as a distillation of godliness into a smaller package with some wiggle room for my own preferences.  I didn’t include the tone stack, PI, or output.  I’ll leave that up to anyone who would like to further tweak it, in case they want to have a feature or omit a feature.  It’s about flexibility.

Some notes about the schematic:

  1. My software barely supports tubes and the pins are all labeled for 6,7, and 8.  This obviously is wrong on some of the tubes, but I couldn’t change it.  V2 and V4 would be 1,2 and 3.
  2. It doesn’t have a model for a regular mono jack or a cliff jack.  The stereo jack works fine enough for demonstration and I’m sure a person would be able to figure out what to do.
  3. You can change the input grid stop resistor to taste.  The original uses an alternate way of attenuating radio frequencies and I chose a small value to prevent attenuating the guitar if it’s volume knob is turned down a bit.
  4. You might consider lowering the value of V4’s cathode bypass cap if the bass response is too mushy.  Removing it altogether along with it’s series resistor might not be a bad idea, but will also attenuate the highs by a great amount and greatly reduce the gain of that stage.
  5. A somewhat smaller value on V3’s anode bypass cap will brighten the sound a little.  That’s there mainly to prevent oscillation, but it’s cutting a huge chunk of frequencies right out of the stage that aren’t going to oscillate.
  6. I made the grid stop resistor for V4 56k.  This is pretty low, but is partially to offer less attenuation and lends some brightness after some of the larger values upstream and to offset some of the attenuation in v3’s circuit.

I welcome any comments, questions, suggestions, or cease and desist letters anyone has.

Diode in Tube Amp larger

I am building an amp and I wanted the ability to add another stage for distortion.  Unfortunately, I have some issues which will prevent me from using another 12ax7 stage.  Looking at some high gain amp examples, I noticed that a great many of them contain one stage that is biased so cold and at such a low amperage/high voltage, they go into severely hard clipping that is a square wave with rounded edges.  Because of the bias point, one side of the signal is going to clip much more than the other; this is called asymmetrical clipping and tubes do it naturally and very well.

Diodes are a low cost way to add distortion.  If designed with some foresight, it can be designed to be “tube-like”, but really doesn’t sound exactly like a tube on it’s own.  Placed between stages, it will get enough filtering through the tubes to not sound cold, hard, or whatever the purists like to say as they push their amps with solid state pedals.

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Split you coils and add distortion.

Split your coils and add distortion.

This has not yet been tested.  I contacted Seymour Duncan and was told that a wire to the “-Input” tab on the back will allow splitting.

Other ideas for modification are:

  1. Use the switch for adding the mix control in and out and forget about splitting.
  2. Use switch for diode distortion, no mixing pot.  Use that pot as a spin-a-split.
  3. Place diodes in multiple places, with higher clipping thresholds upstream from lower ones.
An easy variable fuzz/distortion.

An easy variable fuzz/distortion.

An easy variable fuzz/distortion.

An easy variable fuzz/distortion.

I like both active and passive humbucking pickups for different reasons.  Quality passives have a creamy, “I-Can’t-Believe-It’s-Not-Butter” character that actives usually do not have, but actives have clarity and punch that passives usually do not have.  Then there’s the EMG JH James Hetfield Set.  It doesn’t sound as compressed and hi-fi as many other actives while retaining the punch and clarity.  I love using them and recommend them to anyone for almost any humbucking sound.

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This is a place for me to keep all of the music related things in one place.  Among the things I will be uploading are: DIY effects, tube amp circuit information, guitar wiring mods, guitar tab, ideas, and vanity bullshit.  I don’t mind if anything is shared, tweaked, insulted, or otherwise used as long as it’s not-for-profit and I’m credited/vilified for my ideas.