Companion FY-2 mid scoop?

[carboncomp]

I've got the FY2 on my breadboard and have been playing around with using the BMP tone controls in-place of the original filter section, but sill have a real lack of mids.

As I have ripped out the original filter I can't do the mid scoop mod I have seen on here (putting a pot between the 0.1uF cap in the filter and ground). In the past I'v added a second pot to the muffs tone control to give the muff more mids, is this the best option with the FY-2 hybrid too?


any recommendations?

[Mark Hammer]

1) The BMP type control tends to bleed a lot of signal, which is why it is frequently (though not always) followed by a gain-recovery stage.  The GGG version of the FY-2 has such a gain-recovery stage -  http://www.generalguitargadgets.com/pdf/ggg_secf_sc_bst.pdf - which may be suitable to what you want to do.

2) You can get a lot of mids back, by simply introducing some resistiance between the 100nf (0.1uf) cap to ground in the mid-scoop filter.  You get a lot more signal back, in general, as well, by not bleeding off quite so much signal to ground.  I've used as much as a 50k pot in there, but realistically, you don't need much more than 2k to make one heckuva huge difference.

The BMP control gives you a choice between big bottom with not top, thin reedy top with no bottom, and a bit of each with no mids.  Mods to that circuit allow for introduction of more mids.  The FY-2 midscoop with "scoop-defeat" gives you big bottom and top, with and without mids.  I can see why someone might prefer the one over the other.  Ultimately, your fuzz, your choice.

3) Note that the Orpheum fuzz is basically an FY-2 without the midscoop (i.e., LOTS of mids, and a throatier sound).  Because there is no signal bleed via a midscoop filter, it also has a hotter output.

[Noise-O-Matic]

Wow, Thanks Mark, I've just stumbled across this and that chart is really handy!

[Mark Hammer]

Yeah, it's one terrific chart, if you ask me, and a real contribution here.

Note that the "Fuzz" control in any of these circuits, essentially pans between the output of Q1 and the output of Q2.  Since the extent of Q2 clipping depends on how hot a signal it gets from Q1, any adjustment to the gain of Q1 has an impact on both the cleanest and fuzziest sounds you can get from the circuit.

When I put together the "My Buddy" for one of the anniversary contest prizes, I included a trimmer in place of R3 (as legended on the chart) to adjust the gain of Q1, for those who wanted to be able to get a mild grit with the Fuzz pot turned down or wanted the fuzziest tones possible at all times.  I think it was 500R or so, but anything 1K or under will do.  You'll find it helps to make the choice of Q1 less important.  C536 transistors tend to have an hfe of around 250, but you could probably throw an MPSA18 or 2N5088 in there, adjust the gain down a bit, and get a satisfactory sound.

C4 is shown as going to ground, but in the FY-2 it is actually in parallel with R4.  In that position, it affects how much bass the unit produces.  Omit it and you'll get a less reedy sound.