Any tips for using transformers in Fuzz effects?

[GuitarMatt]

I'm still relatively new to pedal building, so feel free to school me 

I've built several germanium fuzz faces and tonebenders, but I haven't implemented any transformers yet.

I'm very interested in their implementation for octave up and compression effects (Hudson Broadcast and Octavia, etc.)

Any good general-purpose units from Small Bear or similar site?

Any comments welcome! Thank you 

[Electron Tornado]

Take a look at this from General Guitar Gadgets:

http://www.generalguitargadgets.com/effects-projects/octave/tycho-octave/

[anotherjim]

The Broadcast pedals claim to produce saturation in the transformer is contentious. In audio coupling use, the effect on the frequency response is one of the audio transformers most telling qualities. They can make fizzy distortion sound more musical and we could maybe use them more.

Octavers are certainly good with a transformer.

[Marcos - Munky]

Since you're into ge fuzzes, I think a transformer octave is something very interesting to give it a try. I built two of them and I was very pleased with the results.

That said, you basically need a gain stage to amplify the signal, a transformer to step up the signal even more, and a couple of diodes to complete the frequency doubler. So you basically have a big AC signal hitting a transformer, which makes it even bigger. The diodes rectify the signal allowing only the positive part of it to pass. The signal that passes thru each diode will add up their frequencies, doubling it, then you'll have an octave up.

On the gain stage, you can use a transistor gain stage (like Tychobrahe Octave), a opamp gain stage (like Gus Simple Octave Up and Scott Swartz's Screamer Octave) or a 386 (can't really remember where I saw it, I know I tried it once and liked the result).

On the transformer, octave circuits aren't really picky on them, as long as they have something like 3:1 or 4:1 ratio. GGG Tycho Octave schematic calls for a 42TM11 (1k5 primary, 500r secondary, so 3:1), while Fuzz Central calls for a 42TM22 (1k5 primary. 600r secondary, still close enough to 3:1) for the same circuit (http://fuzzcentral.ssguitar.com/octavia.php). The Screamer Octave (http://www.geofex.com/Article_Folders/Screamer%20Octave/tsoctave.htm) uses a 42TL002 (10K primary, 2K secondary, so 5:1). The most important thing is to use them in reverse, as a step up transformer and not as a step down transformer. That means the signal should enter the secondary side, making the primary the output.

Btw, you mentioned Small Bear and they have the 42TL22 but not the 42TM22. You can use the 42TL22 instead of the 42TM22, but they have different physical sizes I think.

I suggest you to give a try on the Tychobrahe Octave or Gus Simple Octave up. They're nice circuits and works great with ge fuzzes.

[teemuk]

I'm not overly convinced that one could saturate a generic audio transformer with low voltages of effect circuits and frequency range of guitar, especially that which is hi-passed to prevent distortion from "flubbing out". Circuits that are marketed with high quality transformers (e.g. Bogner effects with Neve transformers) are even less likely to saturate.

A transformer in a distortion circuit, octavers excluded, is more likely
a) less obvious LC filter
b) differential for push-pull amps
c) generic coupling with or without impedance transformation
Choice a) has the most audible effect. 

[anotherjim]

A 386 driven one?

I still haven't posted any demo of that. Octave sound it can do, but I'm kind of sidetracked by all the other distortion flavours that come with it.
The transformer I used has a large step up when driven backwards. There is one that should come close in the 42T range as noted on the schemo.

[DIY Bass]

Cave pedals have done some transformer based distortions that did not require any power.

[radio]

http://www.muzique.com/lab/pickups.htm

[Marcos - Munky]

A transformer in a distortion circuit, octavers excluded, is more likely
a) less obvious LC filter
b) differential for push-pull amps
c) generic coupling with or without impedance transformation

You forgot d) to add some magical mojo that makes the pedal sells for a higher price.

[11-90-an]

A transformer in a distortion circuit, octavers excluded, is more likely
a) less obvious LC filter
b) differential for push-pull amps
c) generic coupling with or without impedance transformation

You forgot d) to add some magical mojo that makes the pedal sells for a higher price.

e) more mojo with some magical black goop 

[iainpunk]

Cave pedals have done some transformer based distortions that did not require any power.

it does need power tho, in the form of a buffered pedal in front of it.
a friend who collects cool pedals, has one of them passive distortions.
they have quite some problems tho:
the input impedance of those pedals was really low if i recall correctly, less than 10k.
high output impedance
prone to hum and hiss.

but they sound quite generic, just a normal distortion/overdrive middle-ground.

cheers

[jdoughty]

Worth noting too that you can use a transformer and input resistor to act as a buffer for your fuzz face style pedals that normally can't handle buffered pedals before them. Earthquakes devices uses that in their eruptor pedal. Doing that would allow you to put a way before it!

[anotherjim]

If you add on a traffy to a fuzz output stage, the pedals that have clipping diodes across the output will probably end up too quiet. OTOH, there are those based on NE555 timers, LM567 tone decoders and LM386 amplifiers can have very hot output levels and could easily drive a transformer.
The signal itself isn't going to produce saturation in the traffy, rather the frequency response will get changed and resonant peaks can happen. The steady HF rolloff should smooth the distortion in a subtle way - not all that noticable but maybe less fatiguing to the ear.

[iainpunk]

If you add on a traffy to a fuzz output stage, the pedals that have clipping diodes across the output will probably end up too quiet. OTOH, there are those based on NE555 timers, LM567 tone decoders and LM386 amplifiers can have very hot output levels and could easily drive a transformer.
The signal itself isn't going to produce saturation in the traffy, rather the frequency response will get changed and resonant peaks can happen. The steady HF rolloff should smooth the distortion in a subtle way - not all that noticable but maybe less fatiguing to the ear.

i wouldn't place the tranny after the clipping diodes, but before, using a step up tranny to boost it into the clipper.
probably a good idea to have a class B transistor pair driving the transformer, which might also add to the sound by imparting crossover distortion, which is always fun in a fuzz.

cheers

[fryingpan]

My Epi Jack Casady bass has a cheap transformer in it. You can choose between "50", "250" and "500" (supposedly the output impedance: the pickup is supposed to be a low-Z unit). At "50" it sounds most bright, with lower volume; at "500" it's much louder and much more muffled (as if the tone were closed off a bit, but not really). I use it at 250 generally, with 50 giving a more rock sound with a pick and overdrive and opting for 500 for "compressed", mellow sound. I don't think the transformer actually compresses anything, it's just that by cutting treble (in a different way to a tone control) and pumping up the volume it feels as if you lose some dynamics. In other words, transformers do have an effect on tone but at guitar level signals it's just a very easy way to shape the frequency response.

[iainpunk]

well, transformers can clip, which they do quite softly, and more at lower frequencies, while leaving more high frequencies in tact, so they can sound clean-ish while still compressing. it can basically do pre- and de-emphasis with its distortion! that makes transformers so great!

cheers