Fooltone Problems (?)

[Parko]

Hi guys,
I'm going to hit you with another one of those tiring "novice trying to build a boutique pedal but is unsatisfied" threads, and anyone who can put up with it can respond.
here's my problem - i have built a Fooltone Fooldrive (as per the schematic posted here a while back), and i'm in two minds as to whether i'm satisfied. Here are my gripes:

*Tone conrol is not linear enough, and does not have enough overall treble (tried log and linear pots - What the hell is a "W" taper anyways?). It is muffled until about 4 o'clock when it gets kinda brittle, but not open enough.

*Distortion is a bit grainy and kinda brittle at high tone settings (the only way i can get close to that "open" sound -you know, THE strat neck p/u sound). There's harsh high pitched distortion above the note, especially in the attack - kind of like a "hiss" ringing above the note when you play hard. (how do you describe that sound?). I was kinda expecting smooth-as-silk lead tones, but i have nothing to compare it to.

Also, the flat mids option adds a significant amount of volume and gain to the signal when compared to Vintage mode. I live in australia, and it's bloody impossible to find a FD to compare it to - i've had to settle for my TS808 for A/B testing. Is it supposed to do that?

Some things to add also - i used a JRC4558DD opamp, 1N4001 and 1N4148 diodes, and tried both 2n3904 and 2sc1815 transistors. The rest (with the possible exception of the tone pot - again, "W" taper? never seen that in aust!) should be according to spec.

My Questions for those who were brave enough to read the whole lot:
1) (How) can i make my tone control more linear with sweeter highs (more transparent sounding)?
2) What is the possible cause for the high pitched distortion? (i'm sure there's a name for it, but i'm still only new to electronics) and can i fix it?
3) Is this the sound i should expect from the FD2? Is it not the smooth, open sound that people revere it for? (and its more than "personal opinion" or perspective, trust me!)

Thanks alot!

[petemoore]

It soundslike your'e describing a TS derivitave, but I'm not sure.
 IF it is a feedback loop clipper, there are a ton of mods available for it.
 *Tone conrol is not linear enough, and does not have enough overall treble (tried log and linear pots - What the hell is a "W" taper anyways?).
 Try smaller 'small caps', from signal path to ground and/or across the clipping diodes.
 I don't know 'W taper" either, the TS uses a pot I could never find [Steve @ Small Bear may have something...don't quote me...].
 I modded using trimpots and sockets for the R's/C's around the tonecontrol pot...long story...I won't bore you with the gory details...and got it to sound good....others can almost certainly be of more help there.
 I can only mention the resistor cap or cap resistor from the feedback loop to ground...there's a mod [bigger resistor/smaller cap]...someone can jump in I think or I'll have to do some digging.
 *Distortion is a bit grainy and kinda brittle at high tone settings
 Messing with the value of the rolloff caps and cap across diode values...I like the TS for mainly boosting, the Dist, when set high is not what I shoot for...well I use a modified gun for that, a ZW.
 Also try modding the clipping diodes, 1 si back to back with two Si's seriesed, 1n914's or....any clipping diode combinations...
 --l<---
 -->l--
----------------------------------
 -->l-->l---
 --l<--l<---
----------------------------------
 --->l--->l---
 ---l<--------
----------------------------------
 Ge's clipping threshold is lowest, then Si's then LED's have highest clipping threshold.
 Seriesing two diodes raises the threshold [X2].
 The higher the clipping threshold, the more output you get.
 Lower clipping thresholds [back to back Ge's..lowest], make harder clip, less overall output, and let less opamp sound out.
  Check out AMZ's labs notebook for clipping and warp stuff
 GEO dissects the TS for you in the 'Technology of' article.

[MartyMart]

http://www.geofex.com/

Go here and read "the technology of the tubescreamer"
You'll find everything related to changing that circuit type here

The TS tone control is very "basic" and may benefit from using a version
of the "big muff" tone stack .... thats also in the FAQ at the top .

Cheers,
Marty.

[SteveB]

......Also, the flat mids option adds a significant amount of volume and gain to the signal when compared to Vintage mode......

While I can't really offer any help on the tone control & distortion sound, I think that what you are describing in the above quote snippet is actually the comp cut mode. When you take the clipping diodes out of the circuit, the volume level increases & distorts even without the diodes.

The difference between vintage mode & flat mid mode is very subtle to my ears. I have wondered about the way the switch is shown in the Fooltone schematic. I never could quite figure it out.

Regardless, I added the flat mid circuity to my screamer clone, & I like it. Still not exactly like a FD2, but pretty darn close. I think it's a sum of the parts used.

Steve

[dave_neal_59]

Personally, I like symmetrical clipping in this circuit.  My experience with this type circuit (TS9 clone) is that it will sound smoother (less high frequency harmonics) using symmetrical clipping.  I recently made one with 1N914s that I really like.  

Also,  tant caps can add some graininess to the sound.  If you used tant caps (as some fooltone schematics show) you may get better results with poly caps.

[Parko]

I used just plain old film green-caps where the tants are, and it looks like fuller did the same.
I omitted the comp-cut mode (the 3 way switch is far too difficult to find) so i guess my FM circuit must be wrong. It doesn't make much difference at low drive settings, but turn the drive up (which is a subtle change in vintage mode) and then flick it to FM mode and there's a substancial gain boost.
I'll give the other diode options a go, as well as changing a few of the caps. I wasn't expecting to get it to sound exactly like a fulldrive, but i do want it to sound good.
Thanks for yer help!

[mojotron]

For the tone circuit what I like to do is to use a 20 ohm resistor in place of the 220 ohm resistor conected to C5 on the fooldrive schematic. This moves the tone more to the high side and takes some of the mud out of the control.

You might want to check all of the solder joints - it sounds like you might have a bad solder joint.

I would get it working like the TS808 first, maybe even use it in vintage mode with 2 1N4148 diodes then add mods, starting with the fooltone mods. The sound should be very smooth.

You used the right kinds of caps, those green ones are great....

[Parko]

fixed the grainy distortion thing - i think it must have been a dodgy solder joint like you said, mojo. I'm gonna give the tone thing a go, (i think an antilog pot might be the way to go with that one, because it seems slightly more linear with a log wired backwards).

I wired my mode-switch in upside down it would seem, so it's not the flat mids that's louder, but the vintage mode. FM mode has significantly less gain and is quieter at high gain settings than the vintage mode. It's also much less muddy. The sound is cool, it's just quieter than vintage mode. Is that normal?

[mojotron]

fixed the grainy distortion thing - i think it must have been a dodgy solder joint like you said, mojo. I'm gonna give the tone thing a go, (i think an antilog pot might be the way to go with that one, because it seems slightly more linear with a log wired backwards).

Cool! I build things in waves, and it seems like the first few builds in any series I do end up having to be trouble shot as some level.

Ya, even on the original FD-2, that tone control is not good at all - I just use it with the 20ohm resistor and have it set at about 90-95% to the high side, then use the tone control on the guitar.

I wired my mode-switch in upside down it would seem, so it's not the flat mids that's louder, but the vintage mode. FM mode has significantly less gain and is quieter at high gain settings than the vintage mode. It's also much less muddy. The sound is cool, it's just quieter than vintage mode. Is that normal?

Ya, that sounds like the FM is working right, depending on the guitar/amp you're using the FM switch will either make a noticable difference or be slight - I really notice it with Fender fat 50's and Gibson PAFs on the neck pickup..