defx Shard (Crystal Dagger) fuzz->phase gain stage limitations

[Itchy Scratcherson]

[update: the circuit design is perfect, the "limitation" was me, surprise, surprise.] Fired up the first time! I'm new to the circuit so just getting familiarized here, but I need some help confronting the integrated gain staging. Because the fuzz section *drives* the phase section, there's a lack of independence that defeats the point of having separate footswitches for fuzz & phase.

We have fuzz_level and phase_level, but the phase level is driven by the fuzz level. When only one or the other effect is engaged, the volume mismatch is frustrating. One level is different from the other, and neither alone matches the dry signal. With both effects engaged & volume-adjusted, it's fine.

I appreciate so much any advice on how to expand the potential of this great circuit re: separate, consistent volumes regardless of which effect is engaged. Stock, volume setting is problematic. I want better control of the mix: it's possible a dry/wet blend control just might do the trick, and maybe implementing variable gain on the fuzz circuit would top it off for me.

Thanks for help pointing me in the right direction! ~Christopher

[idy]

Looks like a cool circuit. Octave, fuzz, phase... and they say ring mod (which you kind of get from extreme speed on some phasers.)

You are saying the fuzz volume affects bypassed volume?

With the effects bypassed, dry volume is set by the fuzz's level control(

Something is wrong. The schematic shows "true bypass." If any knob affects your bypass volume something is wrong.

And the fuzz produces no volume boost by itself? That also seems wrong. I see lots of gain stages and no severe lossy tone shaping. It *looks* loud. I would signal trace and make sure all 4 transistors are boosting.

And then the fuzz seems to boost too much when combined with the phase? But it wasn't boosting much by itself?

Those VCA phasers, I think, need to cut signal to avoid clipping, so it is common for there to be a volume drop, on this effect that is balanced by a booster, like an LPB on the output of the phaser. I would expect there to be a problem where the fuzz distorts the phaser in an unpleasant way if it is set much above unity... I think there is a big R on the inut of the phaser to avoid that.

is it possible you used "b" taper pots for level instead of "a"? That sometimes makes volume adjustment touchy.

[Itchy Scratcherson]

Thanks, idy! If I installed a transistor backward, I just might have to start drinking again. I'll check that first thing in the morning. Can you lend an idea where/how to tap into the fuzz section for adding a gain pot in there?

[Itchy Scratcherson]

It's very sweet: the phasing is much like a univibe, the phase section's "blend" has more effect/ better versatility than some other very good phase circuits, imo, and the frequency (rate) of the phase goes from reeeaaally slow to ring mod fast. The octave switch on the fuzz side is excellent: not too much, not too little.

[idy]

I'm not recommending another "gain" control in what should be a hot fuzz, but that you get a signal tracing probe and listen to make sure that each transistor in that fuzz is working. Could be wrong way, burned out, not soldered in, don't want to guess. Could be a short or near short somewhere cutting your volume.

Worst thing you cold do is start pulling components out randomly to measure them or something... if you hear a little voice telling you to do that, don't listen!

My questions were:
Are you telling us the fuzz volume affects bypass volume? (nuts, I think you modified your original post to eliminate this complaint... if so, good.)
Are you saying that fuzz, by itself, is or is not loud enough?
Did you use "a" taper pots for the "level" of both effects?
Can you signal probe and confirm that your sound gets louder and fuzzier after each of the 4 fuzz transistors?

[ElectricDruid]

I think idy is right. There's no technical reason I can see on the schematic why that circuit shouldn't work nicely and there's no interdependence really. The only place where that's not true is switching the octave in and out. I can see that might screw up the fuzz level.

Otherwise, you've got true bypass around both the fuzz and the phase, and you've got volume controls on each section to make sure that each section can be set to the same level as the dry signal. Start with the phase off, and set the fuzz so it's the same bypassed and not. Then you've got the same level going into the phase, whether the fuzz is in or out. Then set the phase so its output is the same whether it's in or out. That should be it.

If that doesn't really work, something's not connected right, and if the dry level is affected by any of the controls, something is *definitely* wrong!

[Itchy Scratcherson]

Thank You for reviewing the schematic for me! I'm currently probing. Applying slight pressure to the Fuzz 3PDT bypass gives me a huge jump in volume... so I think I'm looking in the right place.

Do you guys avoid screw-terminals b/c they can be flakey? I'd also appreciate wire recommendations so much! This may change soon, but I never box my circuits until I'm satisfied they're among the best sounds I can add to my rigs, and that means I'm constantly stressing any off-board wiring. So, I often use screw-terminals from Tayda and just put pins in there for testing with my diy test box until I'm satisfied it's worthy of adding actual ¼" jacks, 2.1mm power jack, & stomp switches or 3PDT toggles. (Unless there's a good reason, I keep the terminals & then just plug in any external wires.)

In the pics below I'm trying to decide whether to reflow or remove the green screw-terminals for the fuzz bypass stomp (I started wicking-up the solder there).

[duck_arse]

I have a question - how big are the pins on those screw terminals, do they drop into the board or are they a tight fit? also, when soldering that [I think that] type switch with the thermoplastic body, excess heat on the lugs can cause them to shift enough in their mount that they don't work every time, sometimes yes, sometimes no, sometimes if you push it like this ....

you could of course just use links in the screw terminals and not need the switch while testing, but you'd need to mess the links about for un/bypass.

[Itchy Scratcherson]

You identified the potential problems with these terminals precisely, duck_arse.

Issue is now resolved. I kept the screw-terminals in place and fixed most of what I complained about by just reflowing joints (9 pcb points for the fuzz 3PDT, 3 pcb joints of the fuzz level pot, and 6 for the DPDT octave switch). Now I hear this really is a perfect circuit. True bypass works as it should, and both fuzz and phase levels are independent now as they were designed to be. Volume can be set so the bypassed pedal, or one effect, or the other, or both, are at unity volume.

Adding a wet/dry mix, and a fuzz gain control are next here for me. Not sure how best to phrase this so it's universally understood: in terms of dirt, this circuit gives (a) fuzz, or (b) no fuzz. So I'd like to add another pot to control the amount of ("pre-"?)gain which the fuzz circuit takes in/ puts out. Not for more or less volume... I'd love to control the amount of fuzziness. That's in addition to a wet/dry blend I'd like to add.

Thanks, everyone, once again.

[idy]

Congrats.
Wet/dry will almost certainly require a buffer for the clean side, but that can be a tiny daughter board. When you are ready people can help.
Feast your eyes on this selection:
https://tagboardeffects.blogspot.com/2014/08/buffers.html
You will take the buffer input from input of the fuzz. You will put the blend pot with one side to buffer out, one side from fuzz out... more or less. One issue is that the buffer side will be unity gain (almost) and your fuzz louder. So maybe a boost/fuzz blend? or....

PS: with all those transistor sockets you are lucky it works. Another source of dodgy contacts. I know some build docs recommend "socketing all transistors" but no. Just triple check pinout AND the PCB. So many cases of PCB designed for one but build docs specify another. Find and match C B and E.

[Itchy Scratcherson]

I have a question - how big are the pins on those screw terminals, do they drop into the board or are they a tight fit? <...>

HTH!

[bluebunny]

If you want the convenience of a pluggable connector, take a look at Micro JST.  I've used them where I've got multiple pot connections and where life is just too short to solder a bazillion permanent joints.  I used them on Rob's "Abductor" delay which has, like, thirty pots...

[duck_arse]

I have a question - how big are the pins on those screw terminals, do they drop into the board or are they a tight fit? <...>

HTH!

well now, I was asking about the pin size, because they come in light and heavy duty, etc, and was wondering if you might have had to force too large pins into plated through holes. doing so might have damaged the thru connection, upsetting operation. but, carry on, excellent work. will you be using screw terminals on future builds?

is your too much fuzz the OCT_B transistors section? it looks to me as tho Q1 and Q2 are both setup for max gain-ish, and would prove tricky to degain easily.


also - HEY DINO - if you are looking. I know you do trace and repeat, but the circuit dia shows C10 in series with C11. just C10 would do the job.

also, the b100k BLEND pot shows ccw short to wiper. is that correct wiring?

[digi2t]

Yup, I'm looking. Trace and repeat is the MO, not likely to change. What you coulda got, you get.

Can't remember regarding the blend pot, I'll have to take a gander at it when I get home. Travelling atm. It's a phase blend in pot, but the fuzz is always predominant IIRC.

[Itchy Scratcherson]

is your too much fuzz the OCT_B transistors section? it looks to me as tho Q1 and Q2 are both setup for max gain-ish, and would prove tricky to degain easily.

I've just spent many hours trying to add some sort of pre-gain/fuzz amount in various places, based off my look-see at a number of other transistor fuzz circuits I've built. You're right, duck_arse, the octave circuit is pretty much full blast. This was a stumper b/c taming the dirt in the basic fuzz circuit, then throwing the octave switch and getting slammed wasn't elegant.
I resolved it for myself by accepting the circuit is fine just as it is, and, being a fuzz, I'll just utilize my guitar's volume for less grunge. (And this time the circuit board was more forgiving of my many many desolderings. I also properly mounted all 12 transistors directly to the pcb. That's a lot of socket pins to remove! The board fired up every time, no problem. Damn Laika.   )

fwiw, I probably will continue to order these tiny green terminals from Tayda, they seem to be okay as long as I keep them in mind as a potential weak spot when troubleshooting.

And I'll take a look at Micro JST. Thanks, bluebunny!

I really really love the phaser section of this circuit. Very univibey, and really pretty versatile esp. for just having a few pots.
Thanks for all your help everyone! ~Christopher