shin-ei fy-2 questions re. volume and preboost

[octafish]

I've heard a lot of reports saying two things about the FY-2. That it isn't very loud, and that it likes to be fed a hot signal by a booster. I'm thinking of building one of these as my next fuzz build and was planning on building a booster onto the same board.

My questions are-

a) How much of a boost does this thing like? A little boost like a LPB-1 or a massive hit like an AMZ mini booster?

and
b) Is this the kind off thing you need a gain control for, or could you keep it dimed? ie kayfuzz vs superfuzz

edit: run on sentence

[MartyMart]

IMO an LPB-1 tagged onto the front end should be more than enough
Just use the "wiper" from the LPB's volpot to connect to your FY-2's input
connection.
Then you have an amount of "boost" control outside the box + your other
FY-2 pots .

BTW, I just did a similar thing with a "Fetzer valve" front end into an"Electra" distortion with quite nice results !


Marty.

[octafish]

Cheers, thanks for the fast reply, I was tempted to use the dual tranny front end of a superfuzz but a LPB-1 should keep it simpler. I don't have a breadboard so asking questions about mods I'm planning is a great way to "measure twice, cut once".

[MartyMart]

If you feel up to it, you can use two footswitches and give yourself the
LPB and the FY choice from one enclosure, you'd need a hammond 1590BB for this though !!
It would be more "flexible" and is probably worth the trouble.
There are "two fx in one box" wiring diagrams around , use the search function for these.

Marty.

[octafish]

I think I'll build with one switch to begin with, but it should be an easy mod to add a second dpdt to an existing circuit. You wouldn't really need to mess with the board at all, just cut wires from the input and output of the LPB-1 and add the switch.

[Mark Hammer]

Not sure where you heard that it wasn't very loud, but you MAY have heard from me that a pre-boost adds a little something extra.

This IS a pretty loud pedal, delivering a bigger output at max volume than you'd ever get from a Tube Screamer or a Distortion Plus.

It is actually a close cousin, in terms of design, of the Mosrite Fuzzrite.  There are likely some tonal differences between the two due to transistor choice, etc., but the basic structure is the same.  The major difference between the two is the inclusion of a passive notch filter between the distortion control and the output volume.  In that respect, this unit also shares some resemblances with the Univox Superfuzz, which also sticks a mid-scoop filter just ahead of the output control (although the Superfuzz follows the volume control with an output gain recovery stage).

Two final points: the caps and the distortion pot.

The caps on the original are ALL ceramic.  I don't think that is critical to the sound.  I only mention it to point out that being obsessive about cap type in this instance is wasted effort.  Use what you have in your parts bin.

The distortion pot on the original is wired up weird.  The collector outputs of the two transistors go to the same pot through different value caps.  The schematic posted around shows one of these going to a side lug, and the other going to the wiper, with the signal heading off to the notch filter through the remaining side lug.  I thought this a little weird, and after noting the resemblance between the Fuzzrite and FY-2 thought I would try it the Fuzzrite way.  Here, the two collector outputs go to the side lugs of the pot, the output signal emerges from the wiper.  The pot is acting like a pan control in this instance, placing varying resistances in series with the two alternate transistor outputs at their mixing point.

I can confirm that both wiring schemes work.  Personally, I kept mine (an original board, repackaged in a 1590B) in the panner format since I thought it offered a broader range of tones (which, thankfully, included the ugliest ones too), but since it only involves two of the lugs on the distortion amount pot, you could always build yours with a DPDT toggle to swap the two lugs in question for Fuzzrite or FY-2 format.  Normally, Q1 goes to the wiper, Q2 to a side lug, and output from the opposite lug.  Here, you would swap Q1 from wiper to outside lug, and output from side lug to wiper.

A simple and worthy build.  Thankfully, the 2SC536 silicon transistors used in the original are still fairly available.

[Dan N]

The way the fuzz pot is wired means you always have 50K between the fuzzz part and the output. I put a switch on mine that shorts out the "fuzz" pot. A quick fix to make ot louder. Wiring it the Mosrite way makes MUCH more sense.

As long as you are messing with it, how about having the boost behind the circuit? You get the original "tone" and it will be louder. The recovery stage from a superfuzz might be a taseful choice. How about boosts on both ends?

Try a switch on the big cap in the notch section. The Ibanez Standard has a .022 there, and a footswitch that kicks in a 0.1 parrallel. Changes the filter big time. What's it sound like if you just switch out the filter alltogether?

Good luck!

[octafish]

Thanks guys, I have trawled and assimilated the vast amount of misinformation and opinon on the net and that is where I came up with the low output theory. Plus having added passive notch filters to various circuits I know they suck a fair amount of volume so it seemed reasonable.

My plan is, once I get the time, to lay the pedal out thus.

LPB-1 with a mini-toggle dpdt to bypass for the original tone and to maintain a svelt pedal, -----> the FY-2 in fuzzrite fuzz pot configeration and using a superfuzz style notch/voltage divider switch,-----> then perhaps a superfuzz style gain recovery.
Might have to socket the big cap in the notch as well, leaving enough room to add switchable caps. I love the extremeness of the notch in my superfuzz but I guess I could try subtlety... at least once.