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Building your own stompbox / Re: Mosky Super rat Guts shots and mods
« Last post by Rob Strand on Today at 09:14:06 AM »
From the parts I've examined it looks like a classic rat with no significant changes to the schematic.
The JFET seems to be wired like that, single gate resistor to ground.
Pictures / Re: Pictures!
« Last post by Dewil on Today at 09:07:44 AM »
That looks like a lot of fun. I need to check Electric Druid out.
It would be rather instructive to find videos comparing low and medium gain amps playing jazz, country, pop etc

Of course.... boomer  :icon_mrgreen:
There have been 1/8" audio style jacks for power, though I've never met a Klon Centaur myself. The Jen Super Crybaby for example was 1/8" audio. Now if the enclosure is grounded, the + plug tip will hit that first (doesn't make sense to have the sleeve +), so it either needs a PSU isolated from AC ground (only 2 prongs used from the AC outlet) or a socket isolated from the chassis.
I wouldn't hesitate to change to 2.1 DC jack, it doesn't have this headache so long as a common plastic-bodied type is used.

Oh, and how is Lucille?


It's probably worth noting that the when the HM-2 was replaced by the HM-3 they did away with that 2 transistors + op-amp gain setup in favour of a single opamp whose gain was set by altering the feedback resistor which is a much more conventional setup.

It's IC1a in the diagram:

They also removed the series clipping diodes, used transistor gyrators in the filter section, and maybe tweaked some values but otherwise the circuit topology is essentially the same.
It would be rather instructive to find videos comparing low and medium gain amps playing jazz, country, pop etc
Probably, R26 is incorrectly pointed at 9V..  :icon_wink:

From signal point of view, it contributes (a little bit, due to particular Q7 configuration..) to Q7 stage gain by setting itself in parallel with R27..

New...ish 9V battery.
Pedal switched on, input grounded. all knobs maxed.
Measured using a Fluke 117

Battery voltage measured between pin 2 (9V in), and 3 (0V) on the board: 8.27V

IC1 Voltages:
1: 4.14
2: 4.14
3: 4.11
4: 0
5: 3.63
6: 3.63
7: 3.62
8: 8.27

Q7 Voltages:
1 E: 7.58
2 C: 3.63
3 B: 6.98

What's the benefit of this setup versus more common configurations we regularly see in most pedals ?

What is the role of R25 ?
Building your own stompbox / Re: Component selection for a Klone build.
« Last post by negan on Today at 06:28:29 AM »

3.  I would definitely recommend a 2.1mm center-pin-negative power jack, as that has become a virtual standard for pedals, and will work with most power supplies.

I just found what what 2.1mm neg centre is  ;D

I was thinking of keeping the 1/8” input jack to keep aesthetic originality. I can’t seem to find any 1/8” DC input jacks, only audio jacks. Can I use them, maybe something like this ?

Im also wondering how to wire up the jack to ensure the 9V battery is disabled with I plug the DC jack in and vice versa, the battery is enabled when I unplug the DC plug.

Appreciate any advice on this.

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