freestompboxes.org

Thanks to JehuJava for letting me have at his Resonator. Here's the diagram (click on it to go to Photobucket, and zoom);




Thanks again to JehuJava for sharing.

Insofar as tuning is concerned.....

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! icon_mrgreen

Wow. This is one I really wanted to see reversed. I love the MS20 filter!
I'm wondering why it uses 2 LM13700s and 2 CA3080s... couldn't you get away with 3 LM13700s?

triplesevener wrote:Wow. This is one I really wanted to see reversed. I love the MS20 filter!
I'm wondering why it uses 2 LM13700s and 2 CA3080s... couldn't you get away with 3 LM13700s?

The question came up on the other forum, but like I replied over there, that's above my pay grade. I can only speculate that since each section has the capacity to self-oscillate, there might be a concern of cross-talk. Might also be why there are two separate 072 chips for the resonance, rather than a single 074.

This is a case for Breadboard Man.

Thanks again digi2t. I quite like the idea of a +9v/-9v version using a charge pump running of standard +9v pedal supply, even if the headroom is lower, perhaps the distortion isn't too unpleasant. Might have to try it over the holidays.

I think to a certain point, the headroom at 9vdc should be OK, although the original unit is touted to accept a fairly hot signal.

Let us know what your tests yield.

As a side note, the pedals owner was complaining that CV control was very weak with 0-5vdc CV input. I did some research, and 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.

This just in....

CV also works on 0 - 15vdc. It overrides whatever position the unit pot is at. Pick your poison folks.

Updated schematic is here;

http://www.aronnelson.com/gallery/main. ... alNumber=1

Interested if the two 3080s could be done with a 13600 or 13700. I can get those cheap from Tayda and I have no cheap source on 3080s.

Above schematic link is no longer valid. I had to do some touch ups on the schematic. Here is the proper one;



Schematic, as well as user guide, and tuning info available here;

http://www.aronnelson.com/gallery/main. ... resonator/