B/C/M solid state percussion circuit (much like the Trek II product)

[TheAdmiral]

I could design a pretty damn fast and sensitive trigger detector for that using only op-amps and a few diodes/resistors/caps. I am an E.E. and I have designed 100's of audio circuits from scratch. Any thoughts on this approach?

Build it and post the schematic and some of us experimenters will try it. We'd like to get the use of that drawbar back! FYI, the other drawbars will work as a trigger also.

[jhelm_waterw]

Hi Admiral.
Ok, this is a QUICK first swipe I have at a detector (which is really nothing more than a full wave rectifier, a comparitor and a diode RC coupled together.


The full wave rectifier half I just stole from my previous analog gate design, but the concept is very very similar.
I used variable pots (VR1, VR2, VR3) near the end of the circuit only for debug, then they can be replaced with fixed resistor values after we've had time to monkey with it.
VR1 along with C6 will are a mild filter to keep the circuit from motorboating.
VR2 is the Detector sensitivity control or trigger threshold.
VR3 is a little bit of hysteresis for trigger stability (higher value = faster retrigger, too high = possible false triggers)
The last VR4 though is not temporary. It is the decay control.
This should work connected to any of the bussbars but I would use a higher one for the best/fastest response (make sure you take foldback into consideration)

I HAVE NOT TESTED THIS AS SUCH (I have tested and used up to the end of the full wave rectifier)
If anyone wants to breadboard this and hook it up to a bussbar and oscilloscope, I'd be happy to tweak and talk about it.
A few of the cap values may be tweaked too depending on timing.
I just don't have time right now to build it.

Cheers.

[TheAdmiral]

Thanks. I don't have time to experiment with it just now either but will put it in the future file. Maybe someone else will do it and report back.

[sbaggs]

Geo,
I just want to make sure I understand completely; if I install a Trek II on my C2 I will never regain use of the selected trigger drawbar since the unit is always "on" but not heard when all sliders are at their lowest "off" setting is that correct? Also, since you can select any drawbar to sacrifice which would be a better selection the 7th (1 3/5) drawbar or 8th (1 1/3)?
Thanks,
Sal

[8painting]

Geo,
I just want to make sure I understand completely; if I install a Trek II on my C2 I will never regain use of the selected trigger drawbar since the unit is always "on" but not heard when all sliders are at their lowest "off" setting is that correct? Also, since you can select any drawbar to sacrifice which would be a better selection the 7th (1 3/5) drawbar or 8th (1 1/3)?
Thanks,
Sal

Yes. You lose the 8th drawbar.

Worse case scenario, you just use the bflat preset if you want it.

I just learned this this weekend when I installed my kit. It's not that big of a deal, considering you also lose the 1' Drawbar on any 3-series hammond when the percussion is engaged.


The plus side to the Trek unit is, more sound variability and control, as well as the 5th harmonic.

[geoelectro]

You can select any drawbar for the perc trigger. Since many complain about losing the 1' in the -3 series, Trek II decided to select the fractional footage next to it. That seems to work fine in most cases.

Geo

[sbaggs]

Thanks 8painting & Geo
Sal