# Parentheses C9 Capacitor swap to handle lower tunings



## jnfpbenjamin (May 10, 2021)

Hey ! Just finished my first build :O It sounds unreal, so stoked I discovered this site !

My one and only gripe with it is that it over-compresses or overloads or something when you reef on it with the distortion/octave/boost/level knobs maxed (or various combinations of any of those knobs dimed), particularly so in lower tunings. I've read about this in the troubleshooting section and apparently it's a quirk of this circuit. I read somewhere that you can get around it by changing the C9 cap from 4u7F to 1uF (please correct me if I'm wrong).

Question is, if I try this mod to handle lower tunings (I play mostly in C# Standard), do I need to change any other component values ? Also, any suggestions on alternate C9 values to get rid of the over-compression when one plays aggressively low and slow ?

Gratuitous gut shot included because I'm elated at how this turned out. First time build so if anyone has any pointers for my next one let me know.


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## Nostradoomus (May 10, 2021)

Try a 2u2 cap first. I usually end up at 1uf though but I play in drop F#  🤷‍♂️


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## jnfpbenjamin (May 10, 2021)

Righteous, Thanks ! Is there anything wrong with going straight to 1uF since I happen to have one on hand, or would I just run into an under-compression problem ?


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## Nostradoomus (May 10, 2021)

It moves the corner of your low end response, just play around with it.


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## jnfpbenjamin (May 10, 2021)

Best kind, I'll throw a socket in there and try a few out. Thanks big time for the tip !


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## jnfpbenjamin (May 24, 2021)

*Update:*

Socketed a 2u2 in place of the 4u7 and it totally solved the issue. Sounds unreal, my neighbours aren't even mad.


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## Leftovernoise (May 25, 2021)

jnfpbenjamin said:


> *Update:*
> 
> Socketed a 2u2 in place of the 4u7 and it totally solved the issue. Sounds unreal, my neighbours aren't even mad.


Hey just for curiosity sake, are you trying to add bass or remove bass with this mod? 

I'm somewhat new to this and just trying to learn.


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## jnfpbenjamin (May 25, 2021)

Leftovernoise said:


> Hey just for curiosity sake, are you trying to add bass or remove bass with this mod?
> 
> I'm somewhat new to this and just trying to learn.


That's a great question, I'm not sure what I've accomplished technically by doing this mod. I lowered the capacitor value of C9 to "expand" the frequency range that the pedal would accept before hardcore compressing ("flubbing" to my ears). So my best guess is that I added bass by, as Nostradoomus suggested, "moving the corner of the low end response".

Hope that helps ! If you play in lower tunings (I'm in C# Standard most of the time) lowering the C9 cap value will keep it from dipping in volume when you really chunk on the strings or feed it something that overwhelms it. I was pretty meh about it when I first built it to spec, but now that it doesn't overcompress anymore I'm in luv.


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## Leftovernoise (May 25, 2021)

jnfpbenjamin said:


> That's a great question, I'm not sure what I've accomplished technically by doing this mod. I lowered the capacitor value of C9 to "expand" the frequency range that the pedal would accept before hardcore compressing ("flubbing" to my ears). So my best guess is that I added bass by, as Nostradoomus suggested, "moving the corner of the low end response".
> 
> Hope that helps ! If you play in lower tunings (I'm in C# Standard most of the time) lowering the C9 cap value will keep it from dipping in volume when you really chunk on the strings or feed it something that overwhelms it. I was pretty meh about it when I first built it to spec, but now that it doesn't overcompress anymore I'm in luv.


I might try and do the same swap. I feel like it doesn't have quite the low end oomph I want it to.

If you want it to compress a little less swap out 2 of the clipping diodes with 3mm red leds (not sure if size or color matter but that's what I used). Had modded my old rat to add LEDs as a clipping option and it quickly became my favorite so I did the same on the parentheses.


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## jnfpbenjamin (May 25, 2021)

Leftovernoise said:


> I might try and do the same swap. I feel like it doesn't have quite the low end oomph I want it to.
> 
> If you want it to compress a little less swap out 2 of the clipping diodes with 3mm red leds (not sure if size or color matter but that's what I used). Had modded my old rat to add LEDs as a clipping option and it quickly became my favorite so I did the same on the parentheses.


That sounds rad, which clipping diodes specifically did you swap for red LEDs ?


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## Leftovernoise (May 25, 2021)

jnfpbenjamin said:


> That sounds rad, which clipping diodes specifically did you swap for red LEDs ?


The 4148 pair, I think that's the original rat diodes. Already have a rat with those if I really want those specific clipping diodes. My favorite settings on the parentheses are the leds and the russian germanium d9g diodes I have in there


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## jnfpbenjamin (May 26, 2021)

Leftovernoise said:


> The 4148 pair, I think that's the original rat diodes. Already have a rat with those if I really want those specific clipping diodes. My favorite settings on the parentheses are the leds and the russian germanium d9g diodes I have in there


Rigtheous, I'm gonna socket some Red LEDs in there. My favourite setting is the asymm. clipping, probably b/c of the LED in there - why not try two ? : O


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## Barry (May 26, 2021)

Nostradoomus said:


> Try a 2u2 cap first. I usually end up at 1uf though but I play in drop F#  🤷‍♂️


Goodness, what gauge strings are you using


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## Nostradoomus (May 26, 2021)

Barry said:


> Goodness, what gauge strings are you using



14-72 I believe, custom gauges from StringJoy as I use an Open tuning in addition to it being dropped silly low.


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## mnemonic (May 26, 2021)

I usually run a compressor in front when I use a Rat pedal, just something subtle to knock back the attack of the note as I also like hot pickups and low tunings (though I usually don’t go lower than A). I like the Rat sag but only to an extent. I also like the bottom end the stock Rat circuit offers and I don’t really want to limit that.

to satisfy my curiosity I made a little passive ‘hard limiter’ box, basically just some anti parallel diodes between + and - before the pedal. Works great for this purpose, two pairs of 1n4148’s and a pair of 1n5817’s was enough to clip the tops off hard picking but did not affect softer picking or strumming, and was enough to stop the dropout or whatever you call it when the rat gets a too-hot input signal. I also added a 10k (I think) audio taper pot in series with the diodes so I have some rough control over the ‘threshold’.

if I play just my little limiter box into a clean channel it just sounds like clipping when I pick hard, but into the Rat you can’t really tell, it’s totally drowned out by the rat’s distortion.

I think I will add this diode arrangement at the input of the circuit for the next Rat clone I make.


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## Feral Feline (May 31, 2021)

Have I got old schematics? According to both my PedalPCB Parentheses (reg or Mini) build docs...

C9 is a 100n cap in the Green Ringer portion of the circuit.

So which cap are you chaps swapping from 4u7 to 2u2/1u? The coupler after the Rat's op-amp, or next door to the (in)famous "Reutz" mod? (There're only two 4u7 caps in the entire build doc.)  I'm guessing the latter, as "corner" was mentioned.



Also, if you like the sound of the clipping but find it too compressed you can also double-down on the anti-parallel clipping diodes. I find LEDs clip quite differently and therefore sound different to 4148. If you put two 4148s in series and another two in series anti-parallel to the first two.

Instead of:
>
<
...double down to:
> >
< <

That'll lower the forward voltage and compress less but still give you the 4148 sound.

Take out one of the above or add one as below for asymmetrical...

> >
 <

> > >
 < <



LEDs I like to have 1 red and 1 green or amber:

*>
<*

Of course there's no end to permutations...
4148 > 34n > 4148 >
Schottky < LED *<*

 Too high of a forward voltage and you might not get the diodes to ever reach clipping threshold ( ex. a blue LED or multiple red LEDs).
YMMV, trust your own ears, I'm no expert on this stuff.


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## mnemonic (Jun 1, 2021)

Feral Feline said:


> Have I got old schematics? According to both my PedalPCB Parentheses (reg or Mini) build docs...
> 
> C9 is a 100n cap in the Green Ringer portion of the circuit.
> 
> ...



the 4u7 / 560r by the op amp.

they form a high pass filter at 60hz, so swapping the cap to 2u2 moves the filter to 129hz, and swapping to 1u moves the filter to 284hz.

presumably increasing this corner frequency = less lows amplified by the op amp and therefore less sag/dropout as lows are the highest energy.

there is also the 2u2 / 47r filter which rolls off from 1539hz and below, I believe adjusting or removing this is the ruets mod but I’ve never tried this. Increasing the resistor or removing it would increase bottom end though.


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## Feral Feline (Jun 1, 2021)

Thanks @mnemonic, I figured it was in the filter matrix. Yes, the 2u2/47r is where the Reutz mod is perpetrated.

I'm still curious how you guys were talking about C9 with nobody referencing which schematic, yet building obviously on PedalPCB boards, but obviously NOT working from the PPCB schematic, yet everyone seemed to know which "C9" was being discussed... 😸.


For any bass-players interested in keeping the Rat tone, but *f a t* with better bass retention I liked the G. Tranter Bass Boost mod more than the Reutz, at least in theory. I've done the Tranter mod, but haven't messed with the Reutz just yet. The Tranter mod worked like a charm for my Filigree Siberian Hamster. You could include both the Tranter mod and the Reutz, if you've got space, but I didn't in my 1590A Hamster.


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## mnemonic (Jun 1, 2021)

Feral Feline said:


> Thanks @mnemonic, I figured it was in the filter matrix. Yes, the 2u2/47r is where the Reutz mod is perpetrated.
> 
> I'm still curious how you guys were talking about C9 with nobody referencing which schematic, yet building obviously on PedalPCB boards, but obviously NOT working from the PPCB schematic, yet everyone seemed to know which "C9" was being discussed... 😸.
> 
> ...


I bookmarked a thread from diysb about that mod with the intention of trying it one day 





__





						Proco RAT Ducetone, BASS mod.
					

Proco RAT Ducetone, BASS mod.



					www.diystompboxes.com


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## Feral Feline (Jun 1, 2021)

That's the one!

I used the same version of it as Marcus Effects used, linked from the same thread you posted.


I've got another Rat build in the queue with more space in the box, I'll experiment with "C9" as per this thread.


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