Page 1 of 1
Demon FX King Spark Overdrive [schematic]
Posted: 25 Aug 2021, 06:33
by asbestosaurus
I got one of these cause they seemed cool. It sounded alright when I played it so I ended up tracing it to see what was going on under the hood. Going off the other pedals by this brand I'm pretty sure its a clone, not sure exactly what it's a clone of but there are some familiar elements. A TS style soft clipper with switchable asymmetry into a two-band Baxandall followed by a JFET buffer. (Yes, I know there's a gate resistor 'missing' from the buffer, it is not a tracing mistake, and the circuit seems to work fine without it).
Also I'm fairly new and still don't know how to add the cool [Schematic] tag to the title, maybe a mod could help, thanks :^).
Re: Demon FX King Spark Overdrive
Posted: 16 Feb 2022, 02:08
by CheapPedalCollector
I bought one of these, I have to say this is an interesting pedal and has a lot of amp like compression/sustain that I've not heard similar circuits achieve. It sounds really really good, I'm impressed and it's also very quiet. I'll take mine apart and try to verify this schematic.
Re: Demon FX King Spark Overdrive
Posted: 21 Nov 2022, 02:49
by dmc777
CheapPedalCollector wrote: ↑16 Feb 2022, 02:08
I bought one of these, I have to say this is an interesting pedal and has a lot of amp like compression/sustain that I've not heard similar circuits achieve. It sounds really really good, I'm impressed and it's also very quiet. I'll take mine apart and try to verify this schematic.
Does this have similarities to the old DMB Pedals Sparkle drive? Some of it looks similar. I believe it’s the celestial drive on pedalpcb
Re: Demon FX King Spark Overdrive
Posted: 21 Nov 2022, 09:03
by CheapPedalCollector
dmc777 wrote: ↑21 Nov 2022, 02:49
Does this have similarities to the old DMB Pedals Sparkle drive? Some of it looks similar. I believe it’s the celestial drive on pedalpcb
Hrm no that looks more like a Morning Glory.
I need to take mine apart and trace it, I've just been super busy with repairs lately.
Re: Demon FX King Spark Overdrive
Posted: 21 Nov 2022, 16:14
by dmc777
CheapPedalCollector wrote: ↑21 Nov 2022, 09:03
dmc777 wrote: ↑21 Nov 2022, 02:49
Does this have similarities to the old DMB Pedals Sparkle drive? Some of it looks similar. I believe it’s the celestial drive on pedalpcb
Hrm no that looks more like a Morning Glory.
I need to take mine apart and trace it, I've just been super busy with repairs lately.
Trace what? The DMB pedals sparkle drive? I need to grab one if those off pedalpcb i used to love that pedal.
Re: Demon FX King Spark Overdrive
Posted: 22 Nov 2022, 02:09
by CheapPedalCollector
dmc777 wrote: ↑21 Nov 2022, 02:49
Trace what? The DMB pedals sparkle drive? I need to grab one if those off pedalpcb i used to love that pedal.
Nah, my King Spark, I've been busy so forgot to take it apart and verify the schematic.
Re: Demon FX King Spark Overdrive
Posted: 22 Nov 2022, 03:09
by dmc777
Oh my bad I thought you’d posted the schematic above. My mistake.
Just re-read your description. Probably another reason I thought their May be similarities to the sparkle drive. I think I’ll have to pull the trigger on this one.
I’ve had some good and bad ones on the budget pedals. Have had better luck with the normal size rather than then the minis with the mosky silver horse, deep blue and mooer elady being the exception.
I have a few extras that I haven’t seen uploaded that I’ll try to get too. However I’m no schematic tracer lol.
Re: Demon FX King Spark Overdrive
Posted: 24 Nov 2022, 15:12
by dmc777
This whole time I’ve been saying DMB Pedals Sparkle drive… What I’ve been meaning is the “Stellar Drive” by DMB Pedals.
It’s the celestial drive at pedalpcb
Re: Demon FX King Spark Overdrive
Posted: 25 Nov 2022, 12:53
by ppluis0
Hey !!!
What is the purpose to use a voltage doubler ??
After all, the op amps can't hit the rails if the supply were only 9V as in all others TS clones as the diode clippers limit the available operating range on their outputs.
I personally think that is due a lack of understanding of this boutique builder
Cheers,
Jose
Re: Demon FX King Spark Overdrive
Posted: 25 Nov 2022, 13:24
by FiveseveN
You could still distort the second op amp if you really wanted to (max eq and high input signal).
ppluis0 wrote: ↑25 Nov 2022, 12:53
I personally think that is due a lack of understanding of this boutique builder
But it was DESIGN BY USA! Or designed and built by handmade, not sure yet.
Re: Demon FX King Spark Overdrive
Posted: 25 Nov 2022, 14:18
by ppluis0
FiveseveN wrote: ↑25 Nov 2022, 13:24
You could still distort the second op amp if you really wanted to (max eq and high input signal).
This is also can be happen in the Xotic RC or AC boosters
This diagram has a 15K missing resistor in series with R4 and also the negative leg of the volume pot must be connected to GND !!
Re: Demon FX King Spark Overdrive
Posted: 26 Nov 2022, 00:55
by CheapPedalCollector
It's definitely similar, but still different as the first gain stage is non-inverting and the treble control has 6.8nf caps, the other interesting thing is the 2n5457 on the output. That part is what I need to investigate as it seems to be missing a gate bias resistor. It may be hooked up as a gain stage too, I'm unsure. I'll go take mine apart now I guess as I have free time today.
Re: Demon FX King Spark Overdrive
Posted: 26 Nov 2022, 04:20
by dmc777
CheapPedalCollector wrote: ↑26 Nov 2022, 00:55
It's definitely similar, but still different as the first gain stage is non-inverting and the treble control has 6.8nf caps, the other interesting thing is the 2n5457 on the output. That part is what I need to investigate as it seems to be missing a gate bias resistor. It may be hooked up as a gain stage too, I'm unsure. I'll go take mine apart now I guess as I have free time today.
The 2n5457 on the output followed by the level was what reminded me on the sparkle drive.
Re: Demon FX King Spark Overdrive
Posted: 18 Jan 2023, 14:34
by dmc777
Anyone ever figure out what this is? Is it worth 32 bucks lol?
Re: Demon FX King Spark Overdrive
Posted: 19 Jan 2023, 08:57
by CheapPedalCollector
It's definitely worth 32 bucks, I like it, it has nice compression without clipping too hard.
Re: Demon FX King Spark Overdrive
Posted: 20 Jan 2023, 02:18
by dmc777
dmc777 wrote: ↑26 Nov 2022, 04:20
CheapPedalCollector wrote: ↑26 Nov 2022, 00:55
It's definitely similar, but still different as the first gain stage is non-inverting and the treble control has 6.8nf caps, the other interesting thing is the 2n5457 on the output. That part is what I need to investigate as it seems to be missing a gate bias resistor. It may be hooked up as a gain stage too, I'm unsure. I'll go take mine apart now I guess as I have free time today.
The 2n5457 on the output followed by the level was what reminded me on the sparkle drive.
Once again I called this the “sparkle drive”. I mean the damn Stellar Drive from the old DMB pedals. Interesting drive. With the gain up and pushed it can get almost fuzzy. Can get a great “Time” rhythm and solo using this as rhythm and kicking on prince of tone into it for solo. Works well with the volume knob. Perhaps that’s why it needs to be pushed.
I’d love for someone with the actual knowledge to “upgrade” the stellar driver circuit but I’m small time lol.
Re: Demon FX King Spark Overdrive
Posted: 20 Jan 2023, 11:22
by ppluis0
dmc777 wrote: ↑20 Jan 2023, 02:18
I’d love for someone with the actual knowledge to “upgrade” the stellar driver circuit but I’m small time lol.
Hi dmc,
Perhaps an easy experiment to do with this circuit is solder an 8 pin IC socket in the pcb and try different sigle op amps to compare their results.
For example the LF351 and also TL071 datasheets indicates an slew rate of 13 V/usec which is more than enough to audio applications.
But lower speed single op amps as LM308 and OP77 appearing in the original and recreations of the RAT has only 0.3 V/usec and gives the characteristic response of these pedals.
If you place in that socket an OP07 (designed for industrial applications requiring low drift) that have a merely 0.17 V/usec of capacity, the output bring us a condition named "slew rate distortion"
Cheers,
Jose
Re: Demon FX King Spark Overdrive
Posted: 20 Jan 2023, 14:02
by dmc777
ppluis0 wrote: ↑20 Jan 2023, 11:22
dmc777 wrote: ↑20 Jan 2023, 02:18
I’d love for someone with the actual knowledge to “upgrade” the stellar driver circuit but I’m small time lol.
Hi dmc,
Perhaps an easy experiment to do with this circuit is solder an 8 pin IC socket in the pcb and try different sigle op amps to compare their results.
For example the LF351 and also TL071 datasheets indicates an slew rate of 13 V/usec which is more than enough to audio applications.
But lower speed single op amps as LM308 and OP77 appearing in the original and recreations of the RAT has only 0.3 V/usec and gives the characteristic response of these pedals.
If you place in that socket an OP07 (designed for industrial applications requiring low drift) that have a merely 0.17 V/usec of capacity, the output bring us a condition named "slew rate distortion"
Cheers,
Jose
That’s pretty good info my friend. Certainly nothing I’d thought of. I’ve only heard of slew rate when talking about rats. Thanks for the suggestions