I was reading some info on the similarities between a Spirit Box build and another build that utilizes the PT2399 delay chip. The spirit box currently has a 10k pot for attack attached to pin 6 of the PT2399. The seabed delay uses a 50k pot connected to the same pin I believe. Theoretically would using a higher value pot for the attack on the Spirit Box provide a more robust delay (more repeats) or since the spirit box is labeled as a “pre delay” for the reverb, is the pcb/circuit not set up in a way that this is possible?
Spirit Box Attack Pot value increase
- Thread starter Drlufk00
- Start date
Feral Feline
Well-known member
My understanding is "No".
If I understand the circuit(s) correctly, the PT2399's PIN-6 sets the DELAY-TIME, ie onset/time between repeats, NOT the NUMBER of REPEATS.
Check this out:
ElectroSmash - PT2399 Analysis
Circuit analysis of the PT2399, a CMOS echo/delay/reverb processor by Princeton Technology.
So from PIN-14 the signal gets fed back into the chip's input PIN-16. This would be where I'd start experimenting with the number of repeats being fed into the Belton Brick.
AN ASIDE:
What I find curious is Electrosmash says having anything less than 2k on PIN-6 may result in the oscillator latching up, the PT2399's start up time is 400ms and once started, THEN you can go for a lower value, down to 500Ω. Yet, the Spirit Box has a 1k resistor on PIN-6 — so it may latch up from time-to-time (necessitating a power-off/power-on to try to reboot it to operational condition) ... However, there is an anti-latching method to keep the PT2399's oscillator from stalling...
You can find an excellent example of implementing the anti-latching circuitry in Merlin "The Valve Wizard" Blencowe's PT2399 chorus JENNY GREENTEETH.
It's a few extra components and wouldn't add much expense to the final price of the Ghost Echo — SO WHY THE FUDGSICLE DIDN'T EQD INCLUDE ANTI-LATCHING IN THE CIRCUIT's DESIGN?
To be fair, while Electrosmash says anything below 2k may latch up, while Blencowe says 1k, so I guess EQD went with the bare-minimum resistor value on PIN-6 and saved the company hundreds of dollars on a few-cents-per-unit omission.
ANYHOOHAH... TLDR
Looking at the Seabed Delay and Spirit Box schematics, it'll require some fancy rekajiggering of the Spiritbox to get more
REPEATS out of the Spirit Box's PT2399 — look closely and you'll see there's zero interaction between PIN-14 and PIN-16, unlike the Seabed Delay's PIN-14 and PIN-16 feedback loop.
Were I to try to turn the DELAY section of the Spirit Box into a more Seabed-like configuration, I'd use a scrap of vero or perf to hold the mods and wire that into wherever it needs wiring into on the Spirit Box PCB.