Crimson tom issue after replacing piezos

[oli43]

Hi,

I had a sensitivity issue with a 10 inches tom on my Crimson (toms with sensitivity knobs).
So I decided to replace the 3 piezos on this tom.
I had to remove the foam which was completely dead and replace it with custom made foam from packaging.
Since this fix the sensitivity came back to normal but I have a strange issue: when I play fast hits rim is triggered instead of center.
If I plug the tom with a TS cable instead of a TRS one, center works as expected and I don't have untriggered hits.
The problem happens with the old foam too.
Any idea to fix this problem?
Thanks.

[Chaser]

Hi,

I had a sensitivity issue with a 10 inches tom on my Crimson (toms with sensitivity knobs).
So I decided to replace the 3 piezos on this tom.
I had to remove the foam which was completely dead and replace it with custom made foam from packaging.
Since this fix the sensitivity came back to normal but I have a strange issue: when I play fast hits rim is triggered instead of center.
If I plug the tom with a TS cable instead of a TRS one, center works as expected and I don't have untriggered hits.
The problem happens with the old foam too.
Any idea to fix this problem?
Thanks.

Using a TS Cable instead of TRS just disconnects the Rim Piezo..
The Rim Piezo is directly below the Head Piezo..how was the old one attached?..older designs it was glued directly to the center of the shell..newer design it was glue to an acrylic disc and a foam ring attached it to the shell..the foam ring created a chamber for picking up vibrations..glued directly to shell the Piezo is more sensitive to pick up vibrations transferred from the entire bottom instead of the small chamber.
There are multiple settings..you'll have to either adjust (lower) the Rim sensitivity (RIM SENS) and/or raise Threshold..also HEAD-RIM ADJ which adjusts the signal between the Head and Rim Piezo.
There isn't a single "one setting works for all"..It may take one or 2 or a combination of all of the settings to make the adjustment which is also dependent on your playing style/Head tension etc.
The Sensitivity Knob controls the balance for Inner/Outer Piezo's.
Try setting the Knob from one extreme to the other and make the adjustments.
Set the Sensitivity Knob for the Center Piezo (Head)..make all the Rim adjustments for fast hits...then set to the Outer Piezo (Edge)..repeat.
Then set the Final setting as the difference between the 2...Trial and Error.
You want the Lowest Sensitivity with the Highest Threshold..make sure you do not have too high sensitivity (especially maxed out) on any triggers and the Threshold set too low (especially under 4/5)....that's the biggest mistake I constantly see...you'll have nothing but problems.

[oli43]

Thanks for this information.
Unfortunately I can't get it to work changing the sensitivity and threshold settings. I always have rim triggered when I play fast hits on the tom.
I suspect that the foam I use is not fine for this. I tried two kind of foams with different densities but none of them give me a good reslut.
I already replaced foam in DM10 toms using 3M earplugs (the yellow ones) and this works fine. I'll order more earplugs and try its...

[oli43]

OK, so I continued my investigations and did some tests putting a 500K potentiometer between the ring and the rim piezo, which has no effect.
I decided to unplug the piezo and discovered that I still have the same issue: rim is triggered when I play fast hits.
Does anyone know where to find a schematic of how everything should be connected?
Thanks.

[oli43]

Last test I did: everything is unplugged except center piezo (which is wired directly to the TRS plug board): same problem, rim is triggered!
I really don't understand what is happening...

[oli43]

I suspect the piezo I use to be the problem (from Aliexpress).
I've ordered replacement ones from more reliable website.

[Chaser]

Thanks for this information.
Unfortunately I can't get it to work changing the sensitivity and threshold settings. I always have rim triggered when I play fast hits on the tom.
I suspect that the foam I use is not fine for this. I tried two kind of foams with different densities but none of them give me a good reslut.
I already replaced foam in DM10 toms using 3M earplugs (the yellow ones) and this works fine. I'll order more earplugs and try its...

As far as Foam for the Columns..one I haven't ordered/tried yet is EVA Foam Round Dowels..there are 15mm which is the size of the columns .600....using the 20mm..or making stepped Version..10/15/20mm..etc





Have you tried using a Tom for the Snare?..same issue?
Have you been Disconnecting/Connecting Pads etc when the Modules is Powered On?..

If the issue remains no matter the Trigger/Pad you swapped with Make a Note on your trigger settings if you want to keep them and do a Hard Factory Reset..

Hold < and > Simultaneously when powering on..you'll see a Factory resetting Message.
See if that clears it up.

If You have already done the Hard Factory Reset (Not the Soft Resets under the Menu) and If you have already swapped drums around to ensure that both zone(s) are triggering properly and not the same issue..then it's most likely the DB25 Harness...either a problem with a pin at the connector or the molded TRS...but that's the last resort and you reported everything was working fine until you replaced a Piezo.

EDIT:
Added Link

[oli43]

Hi,
I did a test on an Alesis Trigger IO and I have the same problem.
I think that there is a kind of signal sent to the ring through the ground. Maybe I shoud add diodes on the ground line to avoid this?

[Chaser]

Hi,
I did a test on an Alesis Trigger IO and I have the same problem.
I think that there is a kind of signal sent to the ring through the ground. Maybe I shoud add diodes on the ground line to avoid this?

Don't know what to tell you..other than If you are sure the Foam Columns are making contact with the Head.. start eliminating pieces in the entire circuit...it changed when you replaced Piezos unless you replaced at the Jack and made a mistake somewhere...the Sensitivity Board is pretty straight forward and marked.. + or -

To trouble shoot...Bypass the Sensitivity assembly..
It's basically an Audio Taper A100K Stereo rotary Pot..Horizontal 7-pin with resistors.
The Sensitivity PCB assembly output is wired to the Tip/Sleeve on the PCB on the Jack.
The Rim Piezo (Purple/Blue) is wired directly to the Ring/Sleeve on the PCB on the the Jack.



..De-solder the Red/Black wires (Center/Head Piezo) and tie them together....you can also check the Outer Piezo (Blue/Yellow) the same way..
If the snare works as it should then it's the Sensitivity assembly/PCB Board
If the issue remains it's probably the Jack which also has a Circuit Board , resistors and a lot of Glue covering everything.
There some additional SMD resistors in place  to cool down the signals.
It's not uncommon for something to break internally or get dust/debri in it.

I don't know of anything else strange a Piezo can do except sometimes you'll find one with Reverse Polarity.
Piezo's are pretty simple they either work or they don't (Broken wire..Broken Ceramic) .....some may put out less Voltage.


EDIT:
Added Image.

[oli43]

I did some research and it seems to be related to piezo peak when hit too hard.
The solution seems to be to reduce sensibility.
I used double sided tape to glue it to the board, maybe it's too thin and I should use thicker one or a double sided foam disc instead...

[oli43]

Hi,
For information I received the piezo discs I've ordered from an electronic store and replaced them: it works well.
Il also tried basic piezos from Amazon and I had the same issue.