transformer in octavia

[b_rogers]

what is the purpose of the transformer in the octavia? is it like a amplifier?
can they be used like a preamp?

[Peter Snowberg]

In the Octavia, the transformer is used to make two copies of the original signal, with one of them the opposite polarity from the other.

The diodes after the transformer are pointing the same way so each one cuts off half the AC wave, but because of the polarity being reversed they each cut off the opposite half. The end effect is that the wave is "folded" over on itself so what was the top of the wave before is still the top, but now the old bottom is also at the top (thanks to the inversion) and the old middle is now the new bottom. That's how the octave up is generated.

You can use a transformer to amplify voltage at the expense of current, or you can amplify current at the expense of voltage, but a much better way to state it is that the power is being transformed. Either way you lose some power because the process is not 100% efficient.

Take care,
-Peter

[b_rogers]

hey that makes sense...ok how can you make distortion or boost if you arent using a opamp,transistor, tubes, or diodes? i read bout a new pedal that claims to not use any of these items. it was supposedly a goof while building a octavia and i remembered mine has a transformer in it..

[Peter Snowberg]

If you have excess current in your signal, a transformer will let you trade some of that in for a voltage boost. The one schematic I looked at for an Octavia showed a transformer with a 1:3 ratio and a primary of 500 ohms. If you have a source that can drive that low impedance, just take the output from the whole secondary and forget the center tap. You now have three times the voltage.

The problem is the impedance of the transformer and the weak signal from the guitar. You really need an amplifier in there.

You could get a very high impedance transformer like a 10K to 30K, but those are a little harder to come by and it will only work well if the volume on your guitar is at maximum. I know Mouser has something that would work in that application. Give their catalog a search.  

Take care,
-Peter

[b_rogers]

hey peter thanks for all your help man..i guess ill have to check one of these pedals out myself..of course maybe i read wrong..