Here’s some more info from Martin Freeman about that Spikering circuit, this is gold info and worth mentioning here :
"Spikering looks like sort of a hybrid between the Dogvoice and the Gong.
On the Spikering, check that the filter is working first as that’s a bit easier to grok. The “X” and “Y” resistors are confusing at first, but you can configure them a bunch of different ways:
For variable bandwidth (this is like the Gonzo mode on the Plumbutter Gongs), don’t populate “Y”, but populate the “X” resistor and make it 22K like the other 22K feeding the Transimpedance pin (Pin 1) on the other LM13700 OTA. Realistically, both “X” and the 22K can go as low as maybe 10K for extra range.
For classic variable cutoff frequency, populate “Y” and make it 22K (or see recs above about squeezing more range from the filter). Make “X” 4.7K, but connect one end of it to the PNP collector as per the PCB and the other end to Ground instead of the Transimpedance pin (Pin 16) on the OTA.
For a hybrid of the two, stuff both “X” and “Y”, make sure they’re both at least 10K.
More info about picking resistor values be found in the LM13700 datasheet.
The Pulse Generator is reminiscent of the Dogvoice in some ways. There are two simple high frequency sawtooth oscillators that feed an opamp rigged as a comparator. One has variable frequency and one is fixed (just like in the Dogvoice). The weird configuration of transistors fed by the comparator and another sawtooth oscillator (charged by the delay pot and discharged by the current sink) looks like an old school discrete RTL-style logic gate (I think NAND?). I think the collectors of the bottom too PNPs are pulses that are always opposite one another. So if you have a dual trace oscilloscope, you can see if this is working by observing that those outputs are giving you pulses that are always inverted relative to each other.
Things get weirder because one of the pulse outputs is fed back internally to the variable frequency sawtooth oscillator via the CHAO resistor. The CHAOS pot lets you tune in interference patterns between the two sawtooth oscillators. The node with the symbol will also affect the charge rate of the variable freq sawtooth oscillator."
To bypass the pulser and use as a conventional filter you can fit a switch -> “If you’re trying to use the two sections separately, just lift the leg of the 104 cap that connects to CHAO resistor and wire your jack/switch there.”
Those dash lines caps are 472 caps.
Those caps are the integrators, meaning that the frequency of the filter is much higher than it should be [if using 102 or 103].
Other mods :
Lower the resistor from the Delay pot from 1M to 470K so that the pot would have an effect.
I followed Richards mods and used 10k for X and Y and also changed the wiper value on the delay pot. All my pots are 10k. I used a TL074 instead of 64. The electrolytics are 10uf.
Here’s the inputs and outputs
I think that Rungler pcb would be the perfect combo with Spikering although it works well with 6 and 5 rolls also but really needs some random CV for pitch
