Frostwave Resonator

[digi2t]

Thanks to JehuJava for letting me have at his Resonator. A few little bugs that needed fixing, and those taken care of, I've taken some time to trace it out. I'm still back tracing, but I believe this to be correct, except for some particularities, which of course I would need some opinions on. Here's the diagram (click on it to go to Photobucket, and zoom);



The question marks are;

1) The diodes at the CV inputs. The components are actually silkscreened on the board, and one of the diodes is backwards from the silkscreened image. I don't think that it makes a difference when no CV voltage is input, but I'm speculating that a problem might arise if a CV voltage is introduced. Which way would be the right way?

2) I've done enough bipolar project now, that I realize that the 4.7uF cap on -V to the LM13700 is backwards. Still, it's a bit of a throw off for me, considering it came from the factory that way. I should turn the cap around... shouldn't I?

3) 4.7uF for +V to the other LM13700 is MIA. Spot and pads are there... but no cap. Not even any solder. Guess they must have run out. I should put one in.... shouldn't I?

It circuit is working on +/-15vdc. I haven't drawn the power section yet, but it's coming. Nothing special, just a 7815/7915 setup, powered by a 16vac adapter. I'll add it on shortly, along with any corrections that I find.

Pretty cool box, regardless. Thanks again to JehuJava for sharing.  

EDIT: Updated the schematic. Missed a connection line and cap.

[glops]

Wow 

[Mark Hammer]

Odd, and perhaps yet not odd, that Paul (Perry) would have used a 3080 at the same time as using 13700s.  Jim Patchell shows the distortion specs here for the 3080: http://www.oldcrows.net/~patchell/archives/ca3280_2.html

The 3080's are used here within the feedback/resonance path.  Even though one can see a b2b pair of LEDs in that path, I suspect they are really more to keep levels under control, and the harmonic ringing and edge that the Resonator and Korg PS-3300 have is more 3080-derived.  If you look in those old issues of DEVICE on my site, one of the AMS-100 modules is a voltage-controlled distortion, built around a 3080.

[digi2t]

Thanks for the reference Mark.

I've updated the schematic. I've back traced, corrected, and everything looks to be going where it should. I've added the power section as well.

I'm going to turn the backwards cap around, and install the missing one. Insofar as the diodes are concerned, I still need some direction on that.

[digi2t]

OK, final version is now posted above.

Caps taken care of, and the diode on the LP side was indeed backwards.

With the diode backwards, the resonance adjustment trimmer was forced to almost the very end of it's adjustment. The control was still usable mind you, but there was next to no adjustment left to tweak with. With the diode the right way, it brings the trimmer back closer to the middle of it's range. It doesn't affect the CV input at all.

Insofar as tuning is concerned, I'll post it here, and I'll attach a text file when I upload this to the gallery.

Tuning the Frostwave (My own dabbling. Your way might be better.)
Tools required;
- Small screwdriver for adjusting the trimmers.
- DMM with frequency counter function.
- Your ears.
Procedure;
1) Set all four trimmers in the unit to center.
2) Power up the unit, and connect only the output to an amplifier. Don't turn on your amp just yet.
3) Set the Frostwave controls as follows; LP Freq. max, Input Level max, and Wet/Dry to 100% wet. Set the other controls to minimum.
4) Turn on you amplifier, but keep the volume low. The unit can generate very high frequencies that can hurt the ears.
5) Turn the HP Reso pot to maximum. At this point the circuit should self oscillate. If it doesn't, adjust the 20K trimmer on the HP side until it JUST does. Keep in mind that the frequency of the oscillation may be quite low, so judiciously raise the volume on your amplifier if you're not sure.
6) Once oscillation is achieved, connect the DMM/frequency counter to pin 6 of the TL072 on the HP side (between the 4K7 resistor to ground, and the red LED's). Observe the frequency.
7) Ensuring that the HP Freq pot is at minimum, dial the 1K trimmer on the HP side until the frequency counter shows 30Hz. If you dial up your amp a bit, you should hear a low pulsating oscillation.
8 ) Return the HP Reso, HP Freq, and LP Freq pots to minimum. Lower the volume on your amp as well.
9) Turn the LP Reso pot to maximum. At this point the circuit should self oscillate. If it doesn't, adjust the 20K trimmer on the LP side until it JUST does. Keep in mind that the frequency of the oscillation may be quite low, so judiciously raise the volume on your amplifier if you're not sure.
10) Once oscillation is achieved, connect the DMM/frequency counter to pin 6 of the TL072 on the LP side (between the 4K7 resistor to ground, and the red LED's). Observe the frequency.
11) Ensuring that the LP Freq pot is at minimum, dial the 1K trimmer on the LP side until the frequency counter shows 30Hz. If you dial up your amp a bit, you should hear a low pulsating oscillation.
12) Once the base frequencies have been set, you may tweak the 20K trimmers a bit more to decide at which point the HP or LP Reso pots fall into oscillation. Personally, I prefer it around the 70 - 75% of the pot rotation. If you're going to tweak the resonance at this point, then...
Just remember;
- When working on the HP side, you'll need to max the LP Freq, if you want to hear anything, and zero the LP Reso, so as not to interfere with the HP Freq.
- When working with the LP side, zero the HP Freq and Reso pots, AS WELL AS THE LP FREQ POT. Then raise the LP Reso, and make your adjustment.
- If your ears find that the frequencies are too low when finalizing the resonance oscillation start points, then you may raise the frequency of the side you're adjusting to a comfortable level.

A good test to tell if you're tuning is in the zone, is the didgeridoo test. A didgeridoo is an Australian mouth pipe, which produces quite a harmonically resonant sound. If you've never heard one, Google it.

- Set the HP Freq pot to minimum.
- Set the LP Freq, and Reso pots to max, as well as the LP Reso pot. The unit should be in low oscillation now.
- Raise the HP Freq pot to a point between zero, and the 9 o'clock position.
- Quickly swing the LP Freq pot back and forth between zero and noon.

Nudging the HP Freq pot a bit, as you swing the LP Freq pot, should give you not only a decent didgeridoo sound, but a very good raspy "WOW!!" sound depending on the speed you sweep.

We need to build this sucker into a wah. Seriously people.... do it!  

[Govmnt_Lacky]

Any way to trim down the parts count for the Wah shell effort?

Maybe (2) TL074s, (1) TL072, and (3) LM13700s Cuts it down from 8 to 6 

Can the 3080 be replaced directly with the 13700? IF not, at least you can cut down on the TL072s 

[digi2t]

Any way to trim down the parts count for the Wah shell effort?

Maybe (2) TL074s, (1) TL072, and (3) LM13700s Cuts it down from 8 to 6 

Can the 3080 be replaced directly with the 13700? IF not, at least you can cut down on the TL072s 

I'm assuming (always a dangerous thing!) the use of separate 072's on the HP and LP side might have something to do with crosstalk when using the unit in oscillation. I don't see why an 074 couldn't replace the two 072's, leaving one for the buffering. This would have to be tested on the breadboard though, to ensure that there's no monkey business going on between the HP and LP sides.

Replacing the 3080 with the 13700, is above my pay grade. I dunno.

In my minds eye, I see a wah that has the two resonance pots on the side (HP and LP), and a dual gang pot on the pedal running the frequencies. If it's possible, have the ranges of each frequency independently adjustable (two more pots on the side), like some sort of offset adjustment for each frequency.

Man!! I must be smokin' some strong shit! I'm not even anywhere near Jimi's place!

[slacker]

Looks like the 3080 can be replaced by LM3700s if you want. Unless you really want VC resonance you can simplify it a bit and get rid of the 3080s altogether, and just use pots, look at the resonance sections of other MS20 type filters for examples.

[agoldoor]

A dig2t trace without a vero? I presume it is in the works? =)

[digi2t]

A dig2t trace without a vero? I presume it is in the works? =)

Absa-freakin'-lutely.

Never a matter of "if", just a matter of "when".

[digi2t]

As a side note, the pedals owner was complaining that CV control was very weak with 0-5vdc CV input. I did some research, plus some testing, and found that it's really meant to work with a bipolar, -10/0/+10, CV voltage. I tested with two 9v batteries, and the CV swing was damn close to 100%. Mind you, the units pot must be set to 50% for the CV to swing through the entire range. Setting the unit's pot on one side, or the other, effectively limits the CV's reach to the far side.

So much to learn.... so little time.  

EDIT: Just in... 0 - 15vdc works too, and overrides the position of the pot on the unit. Parameter control is completely CV in this case.

[Ry]

Thanks for the work on this one!  I always wanted to play around with this pedal, but didn't have the money when they were readily available from Paul.

[digi2t]

Updated schematic is now in the gallery. It includes some miner touch-ups, and notes.

Now... it is zeeee vero time, yesssssss.

[bwanasonic]

Thanks for the info about the CV input. This explains why +9v into my Blue Ringer never seemed to work the way I wanted.

[Strategy]

any chance anyone will attempt a pnp or other pcb layout for this?
strategy

[digi2t]

any chance anyone will attempt a pnp or other pcb layout for this?
strategy

I don't know. I have plenty of pictures of the original board, if someone wants to take a stab at it. I was contemplating doing a vero, but got tied up with lots of other stuff.

[Strategy]

I have never done a layout yet so starting with a project this complex is probably not a good idea. I've just had a really hard time with vero...maybe I can bribe a friend or forum member into doing a layout 

As mentioned in the MS20 Filter thread though if someone were to develop a layout I'd be pleased to handle the production and distribution of some board prototypes and potentially a group buy of final boards if it tested well and there seemed to be demand.

[digi2t]

Andy (UKToecutter) and I have developed a method insofar as having boards made and distributed is concerned. We gauge interest on the forums, and from that, Andy does the layout. I then do a survey on at least three different forums, to see how many people would be interested in buying. For a run of 50 boards, we shoot for at least 30 show of hands. We've found that if we can sell 30, the other 20 generally get picked up by stragglers within two or three weeks.

I could do a survey to gauge interest for a Resonator board. If there are enough people into it, I could ask Andy if he can do a PCB. It's just a fickle process though, since what may interest you, may not typically interest enough people to warrant the effort.

[Ry]

Please!  I've been planning to build one of these.  A board would make my life a lot easier.

[newperson]

Do you or UKToecutter ever put up the layouts of the PCBs that are sold to these projects?  If so are they localized to a site/place?