MegaDrum w/ Hart Kit: Experiences and Settings

[fuzzysnuggleduck]

I've tried to read a little bit about voltage dividers, as well as look at those piezo schematics in reference to the voltage divider.

Using wikipedia, I found that if I use two of the same resistors for R1 and R2, the equation is Vout = (1/2) * Vin, basically halving the voltage. Am I misunderstanding? I tried putting the voltage divider at the jack instead of at the piezo because I don't want to hack up my pads. See my attachment for a poor schematic of what I've done. As stated above R1 and R2 are the same value.

Does that make any sense at all or am I all wrong on this one?

[dmitri]

Looks right but you only divide voltage on one input which is connected to the tip.

[fuzzysnuggleduck]

Looks right but you only divide voltage on one input which is connected to the tip.

Huzzah! Thanks again. I having a feeling I'll be thanking you a lot...

So just to make sure I'm reading you correctly, I only need to divide voltage on one pin (the tip) OR I am currently only dividing voltage on one pin (just the tip)?

[dmitri]

Looks right but you only divide voltage on one input which is connected to the tip.

Huzzah! Thanks again. I having a feeling I'll be thanking you a lot...

So just to make sure I'm reading you correctly, I only need to divide voltage on one pin (the tip) OR I am currently only dividing voltage on one pin (just the tip)?

If both the head and the rim are hot, you need dividers on both inputs, i.e. 4 resistors for a dual piezo pad.

[ruffneck]

Just a short update. I made a divider for my snare, and now with Gain 0 i reach 780 as max. I used 2 8kohm resistors, and this should half the voltage output. Now the whole thing responds like it should! I really have to whack hard to get the maximum velocity out from. I'm very happy! Now i have to do my toms also.

/Kari

[fuzzysnuggleduck]

I've added voltage dividers to my snare, snare rim, kick and toms so far but I haven't had a chance to really sit down and test it fully yet.

[fuzzysnuggleduck]

I'm very happy and excited to report that after adding 1/2 voltage dividers on the snare, snare rim, kick and toms... MegaDrum is working AMAZINGLY WELL for me! Yaaaaay! Goodbye, inferior TD-3! I skeptically added some voltage dividers to my input jacks, per schematic posted earlier and once I got to my kit and plugged everything in, it just started responding how I wanted it to this whole time.

To summarize:

The Hart Dynamics 13" Pro snare is good with a 1/2 (50%) voltage divider on head and rim. The Hart 8" kick is good with a 1/2 voltage divider on the head. The Hart Accupad toms however may be a little too attenuated at 1/2. I think I'll try using a 2/3 voltage divider on them sometime in the future and see what difference that makes.

I don't have my MegaDrum with me right now but I'll edit my initial post with the updated settings soon as they have changed significantly!

Thanks so much Dmitri and Synthex, as well as the community! I must say I'm relieved to have this all working nicely.

[Ken Forgettable]

Rather than cool off the input with a voltage divider could a (zener / cap) dc offset be used without any changes to the existing AREF network or choke thresholds - would this increase dynamic headroom?

[dmitri]

Rather than cool off the input with a voltage divider could a (zener / cap) dc offset be used without any changes to the existing AREF network or choke thresholds - would this increase dynamic headroom?

More details and a drawing?

[Ken Forgettable]

Voltage dividers reduce the pd by scaling, DC offset does a transformation about Y (Fig 1).
Shifting the whole thing down can reduce clipping whilst leaving the pd intact.

Fig1_DynamicHeadroomForGain.gif

--Too low!
Just making an observation here - we don't want to kill the switch inputs after all so raise it up to within say 1v as in FIG 2.

Fig2_NeedsPeaksBack.gif

-- Waste of time we're back to a voltage divider!
But Fig 3 is now showing our signal with some headroom and some extra bandwidth to play with.

Fig3_HeadroomWithPeaks.gif

- So what - I've got groupies for my band, all you've got is your right hand.
Note in Fig 4 the hot signal is parametric.

Fig4_TheVariableChoke.gif

Does this mean a variable choke - at last? ... Tune in next week.


PS. In Fig 4:
1 is the multiplex output.
Hot pin 4 (oops, I mean the red one) gets split into two:
side A is AC coupled to remove the DC offset and gets the magic treatment by one ADC.
at the same time side B is being sampled by shall we say PA4.

Whoosh side A has just peaked - better check out side B quick.
Ahh it's smaller - this guy must be playing with his thing again!
Perhaps if I report this he'll get the chair this time...


+ Next week arrives...
Yes it only works when the piezo is struck but by turning on the juice (say 1v) we gain a
continuous controller on every input?