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1
Building your own stompbox / Re: Mosky Super rat Guts shots and mods
« Last post by Rob Strand on Today at 09:14:06 AM »
Quote
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.
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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.
3
It would be rather instructive to find videos comparing low and medium gain amps playing jazz, country, pop etc

Of course.... boomer  :icon_mrgreen:
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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?


5

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: http://i.imgur.com/dlIsUiW.jpg

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.
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It would be rather instructive to find videos comparing low and medium gain amps playing jazz, country, pop etc
7
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..


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

What is the role of R25 ?
10
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 ?
(https://www.mouser.com/ProductDetail/Amphenol-Audio/ACJM-MV35-2S?qs=t8%2F5FiDdxGai2lqRGe%2FRiQ==)

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.

Thanks!
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