Yamaha DTXpress/DTXplorer/DTXtreme

Keith, PFozz, plhalli, et al:

First off, I'm a regular poster on DIYedrums, but maybe I should pay more attention to the DTX groups :)  Keith, fabulous work!  We all knew it was possible...  Thanks for doing what we were too lazy to figure out hehe

Anyway, I tried out your circuit last night (with a Roland TD-7t box and pads), but I had bigger problems...  The main pad (J3 in the pdf) was severely cut down on the sensitivity, and same as plhalli, the rim pad (J1) was sensitive enough, but wouldn't trigger the switch for lighter hits.

My dad, who is much more of an electronics guy than I, first shorted out the diode on the main pad (D2, essentially removing it from the circuit) which cured the sensitivity problem on the main pad.  I might have had the polarity flipped, so the first spike was negative, but removing the diode seemed to bring sensitivity back to normal without adversely effecting the rest of the circuit.  I understand the idea behind this diode (half-wave rectifying), but it's apparently useless, atleast for Roland boxes...  Any idea what the deal is?

To cure the high threshold on the switch, I adjusted the resistance of R1 down.  I brought it all the way down to 1.5k, and now it works GREAT for all hits that can be heard, and I cannot get it to false-trigger the switch on the main pad.  It DOES get confused for VERY light hits, but they're so light that I can't even hear the sound, and the only way I can tell it's messing up is to go into the trigger editting screen, where I can see what's being triggered.  When I build your circuits for use on my kit (instead of on breadboards), I'm going to put pots in there so I can adjust the thresholds.  So, plhalli, since you're having this issue too, try lowering R1's resistance.


Again, thanks Keith!!


--- In DTXpress@yahoogroups.com, "Keith" <keith@k...> wrote:
> --- In DTXpress@yahoogroups.com, "plhalli" <phalli9966@a...> wrote:
> > I have assembled the "cheap DTXpander" circuit that Keith posted to 
> > this site recently and have had partial success with it.
> > A mono trigger wired to input J3 plays the "pad" sound fine. 
> > My problem is with input J1 and it's related circuitry: a mono trigger 
> > wired to input J1 will only play a "rim" sound on a hard hit, on a soft 
> > hit it plays the "pad" sound. Naturally, I want J1 to play the rim 
> > sound all the time, and with at least some dynamic range. Tweaking my 
> > DTX 2.0 brain did not help.
> > If anyone out there has tried this neat little circuit with different 
> > results, or has any ideas on circuitry modifications, please post.
> > Thanks
> > Phil
> > P.S. Many thanks, Keith, for your hard work.
> 
> The DTX 2.0 will not adjust your way out of this problem.  Have you
> got an output adjustment on the pad itself?  If so, increase the pad
> signal as much as pissible using it.  Another possibility is to
> reverse the connections from the pad (a bit of a long shot, but you
> want the positive going peak first).
> 
> If neither of those suggestions don't work then unfortunately you will
> need the complicated circuit - with gain on the rim detect.
> 
> Keith.