GREETS:

I boxed up my 5-knob monster 2-nite in a 1590BB box and a 3PDT w/ a nice green LED(thanks Brian.M.) It's a pretty good sounding box, but I can't help but think that the parametric could be done better somehow. I just really don't know yet what should be done differently. I'm taking baby steps with all this. I think it's still a worthy DIY build, & I'm going to post it in Schematics 2 for your building pleasure.

Heavy Metal Pedal is probably not the right name, as it is too generic, but that was what I set out to do: Build a dirt box for heavy sounds. However, if you turn down the gain, it makes a decent sounding overdrive with nice volume clean-up. If anyone comes up with mods or improvements, please, feel free to express yourself about them here in the forum. Just try to make it stuff you've actually tried in the circuit, and not just theory.

Regards

RDV

When I was done playing with the circuit, I was gonna label it "RDV", cause you created it, and I dunno, it sounds like a good acronym for something... "Raging Distortion Vector" (as in force, influence; course, direction); idea of a raging distortion pedal roaming around, influencing you to take the step in the direction of creating your own pedals...

Or Raging Devil Valve, Redassed Demented Vegetable, etc... just a thought.

Ciao.

Hi RDV,

Quote from: RDVIt's a pretty good sounding box, but I can't help but think that the parametric could be done better somehow. I just really don't know yet what should be done differently.

Perhaps build a parametric as a separate unit, then you could try it before or after the unit, you could also use it to shape the responses for your other effects.

Quote from: RDVHeavy Metal Pedal is probably not the right name, as it is too generic, ...

How about "Heavy Everyday Metal Pedal" so you can shorten it to HEMP. :wink:

Regards,
Will

Tha'ts what I did Will.
 I just left the 'first part' off, making making the input the third OA back from the output, or cutting off just past the diodes sections from the front.
 I've tried it on a SD-1, a Bazz Fuss, and a couple others Like DIST+.
 It does interesting yet sort of subtle effect on the  Bass of whatever you put into it, I would say better low end definition, and fatter sound is added.
 I noticed the ability to get increased bass response from my 'half baked' speakers without them breaking up like they usually do when pumping out bass like that. ...they sound fine up to certain level, that I never exceed for long.
 I found that with the SD-1, there's a 'really strong bass' TS type tone, that's unique and I like. The bass is thick and strong, but doesn't whoof out [swell to a 'whomph' like it tends to], and stays at a more controlled level. The Les Paul I have with Dimarzio's seems to have this 'Bass Whoomph' tendancy...I don't desire...bass notes get out of control easily.
 Anyway the parametric section is a usable circuit fragment, one that has good novelty factor [I've never seen it used around here], gets interesting different tones, works quite differently [of course] with different circuits before [I seem so far to prefer them before] and after.

Playing with this thing some more has me thinking it's the best fuzztortion I've got. I was using the "Bridge of Thighes vibe" into the HMP into an old Ibanez ADL delay @ a very low volume on the neck pickup into the Hiwatt modded Ruby & getting lost in it. Just what I wanted. I'm not playing this weekend, but I'll post again after next weekend when I crank it up to "Patent Applied For" through the old Marsnall(h broke off), and the real truth will be evident.

I named it wrong for sure, people who hate the very idea of metal are going to be put off. It's way more versatile than just a Heavy Metal Pedal.
I don't even play metal, just listen(hit the www button below) to my candy-ass pop sounding band!

Build Forrest!! Build!!!

RDV

I used a 10k trim for the diodes, a 1 meg for the gain, and a 100k resistor..I'm running out of pots!! for the 50k pot.
 Thing is Hot !!! I like the two diode clipping 'double pairs'...
 Just got it fired up, havent' done much testing, NICE...
 This is just the 'light' version, I have the heavy side done also...been doing some building and fixing this week!!!
 Heavy Metal Pedal
 Fetzer Valve
 ODIE
 and re-worked a globby beat up 847 wah board...I think that's it...
 I can say they're all gRRReat !!!
  Right back to it...testing time !!!

Really moddable, with all the diodes, the diode trim etc.
 I was playing with different rolloff feedback loop cap values, at the same time re-valueating the caps between the 4k7's and 1/2v.
 Then there's the diodes, right now trying LED and two Ge's to ground and four Si's in the feedback loop.
 Very wide variances in tone...I'm using smaller than 'schematiced' caps between the 4k7's and 1/2v. This 'attenuates highs, then different feedback loop cap and diode to ground caps, tuning the highs...need at least a .001uf, preferably .0015uf in the feedback loop for effective hiss control.
 ...OK I put .1uf's from 4k7's to 1/2v by mistake...good mistake...and added parallel caps to them to tune up the highs to suit me.
 I started like I do with a TL082, so I don't blow one of my nicer ones, the JRC4558 sounds markedly different in there.
 Can get pretty darn heavy, I like the LED to ground, because it lights, and lets out some punch. Going from assymetric to symmetric...all interesting...[sw them?...] then doubling up on them...almost too much fun, I must have tried 20 mods in 40 minutes.
 I'll be going back when I fresh, and work some more tuning on it. I'm thinking a diode/cap combination ala warp control mod for the diodes to ground, and maybe stick a coil in somewhere, for a touch of 'pickup peak'.
 And of course try it with it's 'other half', the right and lower half of the schematic, the PEQ section.

hey, that two knob one you posted the other day worked great!! i had to put it in a lunchbox tho, but still KILLER DISTORTION!!
try it people :wink:

Not nice at high gain... :shock:  MEAN :evil:
 Yupp, what a Fuzztortion!!!
 I played alot with diodes, caps a little more.
 I have three seriesed Si's {>} and two seriesed Si's {<] in  the feedback loop, and a cap marked 102...   .001uf
 The signal to 10k to ground socket has 2 Seriesed Si's {>} and two Ge's seriesed [<], with a tant cap [probably around .0022uf] for bass rolloff.   Welll I'm guessing it's a tant, came from a puter keyboard, very smal, 'different' shape.
 Big Time Distortion Machine. I think when I was tuning the diodes, I hit some 'random' magic formula I liked, sounds great with 8 Si's like schematic, I decided to leave the 'oddball' diode configuration in there for assymetrics...it's just sounding great...time to stop diddling and start fiddling...with the knobs...these are unique knobs...didn't take long at all to tune them, then I had a long test session...quite enjoyable.
 Next is to box this thing. RACO isn't going to do it either...probly have to find a nice workpiece and pound one out. :roll:  :wink:  

Glad ya'll like it! I'm diggin' it myself. I like the nice clear tunable low end.

Pete:
Did ya try through the plexi? huh? Huh? Wat dat sound like?

We must give thanks to Alfonso Hermida who helped me every step of the way, and to R.G. for his EQ article.

Regards

RDV

Quote from: willHi RDV,

Quote from: RDVIt's a pretty good sounding box, but I can't help but think that the parametric could be done better somehow. I just really don't know yet what should be done differently.

Perhaps build a parametric as a separate unit, then you could try it before or after the unit, you could also use it to shape the responses for your other effects.

Quote from: RDVHeavy Metal Pedal is probably not the right name, as it is too generic, ...

How about "Heavy Everyday Metal Pedal" so you can shorten it to HEMP. :wink:

Regards,
Will

LOL

This may go on forever...but. The schem as I have posted it has some issues I was unaware of. The parametric section only cuts or notches the sound, which sounds cool & gives you the option of either unaffected sound(with the Bass knob fully clockwise), or a tunable cut or notch(to varying degrees as you turn the Bass knob counter-clockwise). I hope I've been very clear about this. Of course this is not an issue with the the 'Light' version as it has no EQ whatsoever. :wink:

I'm now going to post a new version of the Schem(Ver.3) which has some changes that allow the parametric to cut and boost. It can get pretty hairy in the boost mode, and I would suggest using a center detent 10kb pot for the Bass cut/boost knob. Again, if anyone tries it, let me know what you think.


Regards

RDV

Ok, I rebuilt it this after-noon, so yeah, definately better now. The difference from one end to the other of the bass pot is more dramatic. Only Issue I've been having is oscillation as the resistance on the frequency pot gets higher (with some stumbly octave-down effect when I play on the high strings). I tried taking out the 2.2k resistor in  the fb loop of IC2a (as it had caused problems in an earlier post), but that didn't do anything. I also tried changing the .01 cap in the gyrator (just in case), but still there. It dissappears if I tied the frequency pot to ground instead, but not the same tone at all.

The only difference in my built from the schematic is the Ge diodes in the second clipping stage and took out the 1k trim, and a .1 uf cap (instead of 1uf) going to Vb from the first gain stage. I changed them back to the given values, still got oscillation.

And one thing wierd, that 500k pot in the first gain stage, it reacts differently depending on how I hook it up... If I hook up the wiper on the "inverting input" side of IC1a, it cut down the gain from middle to either side. Not so when I hook it up on the Output side... is my project board/pot screwed up? Or does it matter which side is hooked up where when you used a pot/trim as a variable resisotr?

Hope I'm a least helping a little, instead of cluttering the boards with newbie non-sense

ciao.

PS: I notice alot of points in your circuit are referenced to Vb instead of ground, how does it affect how the opamp will react? Explanation or link from anyone would be appreciated

I got a little bit of low-frequency oscillation at first, but it went away when I added some resistance at the resonance trimpot. Start with it at 0 ohms and then bring it up slowly, it should do 2 things. It should make the EQ a little less wah-wah-ish as you sweep the freq pot(because it broadens the Q or makes the sweep area of freq wider), & it should cut out the low-freq osc.

The reasons for the Vr tie-ins is so the 2 OAs will properly function. They all need to be there. This circuit requires some tuning, though not near as much as some others. The resonance trimpot seems to be crutial to making the parametric behave.

The pot thing can be kinda weird when you use them as a variable resistor. I've had problems with polarity and stuff, you know, working backwards and stuff. I tie pins 2 & 3 together when I do it, then switch them around if something is wrong. As for breadboards, I don't know, I never use them.

Hope this helps

RDV

Thnx Trouble is, I like the wah-wah-ishness

Anyway, I tried you suggestions and t did some good, but like I said, I really like it the way it is, if I could get rid of the oscillation in this setting. I also tried other OA's (the original I used was a TL072), a Burr Brown (OPA234 or whatever the dual one is), TL082 and a 5532A (the TI 4558) and all three didn't cause any oscillation, but they get rid of some of the highs...

I'm thinking I have a serious problem with my project board or my parts, it's normal for the pedal to work badly if the battery gets low, but I stuck a new one (9.72V reading) and it kills some of the distortion...  :oops:  :lol:  :evil:  :roll:  :?:  :!:  :shock:

Can you post some voltage readings from your build?

"Life is like a box of chocolate: the pieces never look like the picture on the back of the box..."

Anyway, tomorrow.

If you really like the wah-wah-ness(WHAT A WORD) of the circuit, then I would just barely open up the Q(resonance) pot, or even remove it from the circuit. Of course 1 way to approach  it is to find the value you like and replace with a fixed resistor.

I've only tried JRC4558 in the circuit though I bet NE5532 or the Burr-Brown would work quite well. I just had a bunch of JRC4558 that I had removed from other circuits where others worked better, so I used them.

It's widely known that some distortions sound better with a weak battery. While I was building the prototype, I was using a weak battery (about 8.4v or so) which sounded pretty good. Live I don't use batteries at all though, so when I boxed it up I just put a wall-wart jack in it with no battery snap at all. It has a little less distortion that way, but plenty for me. I just really like the nice tight focused sound it seems to have. There's a thread going on about the 'Plexi' sound and how to get it with a pedal, and I almost posted about this pedal doing that (I think it does), but I resisted (not wanting to seem over-zealous about a brand-new un-stagetested device).

The voltages are what they always are on an OA distortion. Most of the pins on the OAs are at Vr (or very near) except for ground (pin 4) and the 9v (pin 8) supply.

I'd like to hear from someone gig-testing it. I will next weekend, but till band practice on thursday I will only be doing bedroom volume tests. I like it so much at low-volume though that I won't be real disappointed if it doesn't work live cause it makes it sound like you're playing cranked up when you've just barely got it on.

A lot of guys won't build if there's not a PCB to a pedal, so I'm going to see what I can do about that. I've had no volunteers to do it so far, so I guess I'll have to do it. I've never done it before, but I'd never designed a circuit before either so here we go.

Regards

RDV

oy, I'm working on a perfboard layout (actually working on making not confusing). Ain't that great, but it's a starting point if nothing else.

Ciao.

Edit: read next post.

ok, I am still a moron (don't ask) but this time I' confident I got it right.



Not the easiest circuit to perfboard But this should help. I'm so glad I have experience drawing pixel chars... I think I'ma do some more layouts now  :twisted:



Ciao.

Edit: K, made the change.

Btw, about metal pedals sounding better with a lower voltage, I'm thinking using a 10k trim instead of the first resistor from 9V would let one adjust Vb when using a fresh battery. Or if it's more related to the IC power, use another voltage divider to adjust that. I've seen something like that (or exactly that) over at GEO.

That looks great!

Thanks

RDV