octavia transformer swapping

[bonkdav]

since the octavia gets its octave sound from the transformer and diodes at the end of the circuit (at least thats what ive read). would it be possible to put a transformer that isnt 3:1 and change the sound.  I want to build another octavia or neoctavia and socket the transformer and then see if i can get it to either A: completely destroy the sound and cut through the mix (Machine) or B: find one to produce harmonies or something instead of octaves.

so if anyone thinks this wouldnt work or if it would be worthwhile or someone has already done it or even think they know a transformer i should try let me know. 

thanks
Davis

[Pedal love]

You probably could but the gain of the circuit should be altered to compensate, don't you think?

[bonkdav]

i never thought of that, you could be right, hopefully ill be able to at least hear each one i put in and then if i find a good new swap i can change up the circuit.

alternately i could maybe go this route..
does anybody know of a clean transformer octave up i could build? that way i dont have to put up  with the fuzz when sampling.
like a boost with the transformer and diodes on the end would that work?
i recall seeing in the forum once someone who was trying to figure out how to bypass the fuzz stage in an octavia, if that would work thatd be great.

im fairly new to designing and modding, actually this is my first time trying my own idea in a circuit instead of just building by numbers so hopefully everyone can bear with me.

also how exactly would i go about compensating the gain?

[GREEN FUZ]

No offence but a quick search goes a long way around here. If after searching you still haven`t found the right answers by all means ask.

Here`s a start.

http://www.diystompboxes.com/smfforum/index.php?topic=59570.0

Good luck with your project. A breadboard is a great way to try out the sort of ideas you`re talking about.

[bonkdav]

thanks green fuz i did some searching and i found the circuit i was looking for its called the octo booster.

http://www.diystompboxes.com/smfforum/index.php?topic=46021.0

i just ordered a breadboard (thats how new to this i am) so im going to spend a bunch of time going through my salvaged circuit boards to find any and all transformers to plug into it and see what will happen.

so now my only question is does anybody know how to calculate what will come out of the transformers?

im guessing there has to be some math behind the 3:1 ratio to produce octaves and im hoping that after (if) i figure out a new transformer they can be switched between with a stompswitch so you can go from octave fuzz to maybe harmonizing in 3rds or 5ths or doubled octaves or maybe just completely mangle your sound at will.

[R.G.]

im guessing there has to be some math behind the 3:1 ratio to produce octaves and im hoping that after (if) i figure out a new transformer they can be switched between with a stompswitch so you can go from octave fuzz to maybe harmonizing in 3rds or 5ths or doubled octaves or maybe just completely mangle your sound at will.

I wish it were so easy. Unfortunately the ratio of the transformer has nothing to do with the ratio of frequencies it produces. There is some math behind the 3:1 ratio, but it's for amplitude compensation, not frequency changing. You can put in a number of different transformers easily enough. That will affect the size of the output signal directly. A 6:1 transformer will make an output signal about twice as big. But it will still be an octave.

What makes the octave effect is that the input signal is full wave rectified. That is, the positive halves of the signal are left positive, but the negative halves are "folded over" to make another positive half. Everything in the output happens twice as often as it did in the input wave, so your ear thinks "octave!". There's miscellaneous distortion junk produced as well.

There is a effect that can produce 3rds, 5ths, etc. It was designed by Robert Penfold, and appeared in the UK mag, Electronics and Music Maker. It uses a phase locked loop (PLL) to lock to the input frequency and up-multiply by integers: 2, 3, 4, 5, 6, etc. and then divide down to get intervals: 3/2, 4/3, 5/3, and so on. Your ear hears these ratios as harmony. The article is available on Mark Hammer's web page.

[tcobretti]

Just so you know, the Machine is a very different thing from what you are discussing.  I haven't heard it, but the circuit is transistor based and does not generate an octave.  It uses something like an overdriven Class B amplifier to create the crossover distortion that it apparently produces.  I say apparently because I am no expert, and don't want to sound like I think I am one.

The Octo-booster is mine, and it is a pretty cool project for the very small part count.  It is fairly clean, but is not the best clean octave generator.  However, in front of a fuzz or overdriving an amp it is pretty sweet.

[hellwood]

i recall seeing in the forum once someone who was trying to figure out how to bypass the fuzz stage in an octavia, if that would work thatd be great.

sounds like you could try the JFET doubler?

[bonkdav]

Just so you know, the Machine is a very different thing from what you are discussing. 

The Octo-booster is mine, and it is a pretty cool project for the very small part count.  It is fairly clean, but is not the best clean octave generator.  However, in front of a fuzz or overdriving an amp it is pretty sweet.

i mentioned the Machine because of the unique sound it produces.

i still plan on building the octo booster, but just for fun now.

thanks for setting me straight R.G. you saved me a lot of time and dissapointment.  Im also going to look into that Robert Penfold circuit because that sounds like what i was aiming for.

thanks to everyone else too.  im going to college this fall for electrical engineering so hopefully ill be able to learn a ton and in 2-3 years ill be able to give some advice instead of always ask for it.

[R.G.]

Good deal, Dave.

Keep thinking. What I neglected to say was that a mind that thinks about "what happen here if I change ...this... a little?" is worth a whole lot.

My wife laughs at me because I'm forever looking at some part of a building, or door, or machine or whatever and saying "... ah, OK. That's how they do that!"

Dig in at school. You have the right kind of mind.