Wow! Awesome. Would love to see your schematic with these CV extensions. I really think is very usefull to have this extra option available. Thanks for sharing.
Here is my complete schematic, inclusive extensions. It is blockwise, as I tested each part with LtSpice following Moritz’ video.
2 Likes
Thanks for your quick reply. Really appreciate it and many thanks for the schematic. As soon as i get homevi will take a look at it. Have a nice day
2 Likes
Just uploaded my nasty remake of M.A.R.R.S.’ Pump Up the Volume and a Fortnite emote. All sounds are made with the FM Drum Synthesizer with some delay added on the toms. The toms and cymbals are voltage controlled via Carrier CV extension from a MIDI track.
2 Likes
Here another track example with a Kick Drum and two different HiHats:
1 Like
Nasty after-work video of my SEM clone sequenced to a techno sound, in conjunction with Moritz Kleins FM Drum Synthesizer and my Voltage controlled MIDI Arpeggiator
2 Likes
Cool. Mine sounds the same. I do notice something strange. Why does the 2nd pulse sound, sound different then the 1st triggered sound? The kickdrum for instance. First triggered pulse sounds different then the 2nd one. As if there is another pulse triggering the module or the 1st gate is not the same as the second gate. Hope i explained well.
I noticed different kicks when the bpm go too fast. C18 of my circuit (ENV) seems to discharge differently according to my unproved assumption.
I noticed a similar behavior in other analog drum emulations like low frequency resonating filter patches initiated by rather high frequency gates.
1 Like
A clock module should output the same gate/trigger voltage each time, so how can the sound be a little bit different by each 2nd gate trigger? As you mentioned i do too think it has something to do with discharging capacitor. Should a diode to ground do the trick to discharge caps quicker? Maybe i ask AI see what possible solution “it” comes up with
1 Like
This sound variation occurs because your gate trigger pulses are arriving faster than the envelope capacitor (like a sample-and-hold or VCA decay cap) can fully discharge. Each new pulse re-triggers the envelope, but because residual voltage remains, the new cycle starts at a different baseline, changing the resulting pitch or volume.
To stabilize the sound, you need to ensure the capacitor can reset completely between your gate triggers. Here are a few ways to achieve this:
Lengthen the Trigger Interval:
Space out your gate trigger pulses to give the capacitor enough time to discharge to ground.
Adjust Resistor Values: Decrease the value of the discharge resistor in parallel with the capacitor. This speeds up the RC time constant, allowing the voltage to drop faster.
Use a Reset Circuit: Incorporate a small transistor or a logic switch to actively short the capacitor to ground immediately after a gate pulse, guaranteeing a clean slate for the next trigger.
2 Likes
That’s what I assumed. And thanks for the hints
2 Likes
Ok, here’s what i did. And works
I used a mosfet (BS170) and connected:
Pin 1 drain (left) to the + side of the 1uf decay capacitor (or one side of the potentiometer)
Pin 2 gate (middle) to a 220 ohm resistor, and the other side of the resistor directly to the gate input jack.
Pin 3 source (right) to ground.
This way the decay capacitor will be discharged faster. Hope this helps.
1 Like
According to spice there is not much difference. How does your env look like after the change?
1 Like
At first i thought it was working but it still occurs. Should the leading diode not be disconnected from the trigger opamp output? Since the gate signal goes to the mosfet directly from the jack.
The gate signal still gets to the diode and then to the capacitor. I dont understand how the mosfet can discharge the cap faster, while sitting in the existing circuit.
Is 1uf cap to big?
1 Like
At the end it is a matter of taste. Do you want a lot of bpm, so a smaller capacitor would make sense, or do you want longer bass curves for deeper tones? You could make the capacitor switchable, like the Moog Modular 904A ladder filter or other modules offer.
3 Likes
if i remember correctly, this is caused by the oscillator reset circuitry. sometimes the wave will rise after the reset, sometimes it will fall. both cases sound a little different. i assume there is some way to make it always behave the same, but i liked the slight variation so i kept it like this.
4 Likes
Hi Moritz,
Thanks for your reply. Hope you doing well.
Yes, its not a big issue as long as kick drums sounds the same. For the rest i think your right about the small variations that comes with it. I do like it to. Thanks again and have a nice day.
1 Like
Hi Moritz. How are you doing?
Can i ask you a question real quick?
My Decay knob is only working just a little bit (when no decay cv connected to the jack input), but when i insert a cv then its working fine. Is it possible that when nothing is inserted, that i need to connect it to ground via my switched audio jacks in order to get the decay knob working without cv?
Thanks for the advice.