Who knows the real trick to get more bass? (RAT)

[JackSkellington]

Thanks guys. I knew that BB Mod. I tried a 220R and a 10uF.
The Fat Rat add a 6.8uF in parallel to the 2.2uF. Indeed, I tried to replace the 2.2uF with a 10uF.
I noticed just the usually tame of the highs.

I can't try again all these. Next time I should try harder, or I'll let it go.

[thesmokingman]

one last thing, I don't know how anyone else does it but if I cut less bass before clipping I like to up the Vf of the clipping diodes some to compensate. ymmv

[garfo]

There is no real way of adding Bass to the circuit without adding more active circuitry to it. Everything else is a compromise between reducing highs and apparently increasing the bass. Once that happens we loose the character of this circuit and in my opinion it's no longer a Rat because it loses it's bite. Ideally, a parallel active circuit should be created and a low-pass filter taken out of it. By adding a mixing stage to blend both the original Rat signal plus a Bass boost control we could possibly achieve greatness.

[jimilee]

^^^^this^^^ A blender board would be the ideal way to go on an over drive or fuzz.


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[midwayfair]

Everything, even adding more circuitry, is a compromise.

Look, your signal is a flat line if you do no tone shaping:

-----------------------

If you add more bass, you get something that looks like this:

-----____________

If you cut treble (with a shelf filter), you get something that looks like this:

-----____________

It's the same thing.

If your complaint is that the RAT cuts bass, do what I said and make that negative feedback cap 220uF. 10uF is almost meaningless, it's giving you a little more midrange but doubling the cap is only 1/10th of an octave. You'll have more bass and exactly the same amount of everything else, because the cutoff frequency will be the threshold of human hearing. It'll also probably sound like the treble is out of balance, because now you've got full bass in a circuit that already cut treble, but you didn't notice because the circuit used to cut bass.

[MJ_Sound_Cubed]

Hey man,

Maybe this will help out:

http://www.muzique.com/news/quick-rat-pedal-mod/

[Matt]

So, here is what I do. uF caps don't carry audio. Film caps do. So I would take the first film cap in the audio path which looks like a 22n, and make it a 220n, then I would do the same thing to the last film cap. I've never done this with overdrives, but I have done it with filter pedals.

That's what I thought as well. C12 it's a 22n and looks to me at least like it's making a high pass filter with r10 @ 723Hz. Or am I missing something?

[Aentons]

Anybody try a different opamp along with the other filter mods?

https://www.electrosmash.com/proco-rat

"In the Clipping Amplifier Stage, there is a double RC network which places two poles and attenuates harmonics below 1.5KHz.
There are several high pass filters, but the Tone circuit and the op-amp bandwidth limit will roll off harmonics higher than 1KHz."

[reddesert]

So, here is what I do. uF caps don't carry audio. Film caps do. So I would take the first film cap in the audio path which looks like a 22n, and make it a 220n, then I would do the same thing to the last film cap. I've never done this with overdrives, but I have done it with filter pedals.

That's what I thought as well. C12 it's a 22n and looks to me at least like it's making a high pass filter with r10 @ 723Hz. Or am I missing something?

C12 is 22nF and R10 to ground is 1M.  That makes a corner frequency of f = 1/(2pi R C) = 7.2 Hz. It shouldn't have any effect on audible signals.  Sometimes the first and last coupling caps don't filter out audible bass.

BTW, I have read the datasheet for the LM308 op-amp a few times and have never persuaded myself that its slew rate or gain-bandwidth are so low as to make a difference at guitar frequencies (up to 5 kHz or so).  The Rat circuit just kinda sounds like a Rat. I think if one wants something that sounds different, maybe a DOD 250/MXR Distortion+ ?

[Matt]

So, here is what I do. uF caps don't carry audio. Film caps do. So I would take the first film cap in the audio path which looks like a 22n, and make it a 220n, then I would do the same thing to the last film cap. I've never done this with overdrives, but I have done it with filter pedals.

That's what I thought as well. C12 it's a 22n and looks to me at least like it's making a high pass filter with r10 @ 723Hz. Or am I missing something?

C12 is 22nF and R10 to ground is 1M.  That makes a corner frequency of f = 1/(2pi R C) = 7.2 Hz. It shouldn't have any effect on audible signals.  Sometimes the first and last coupling caps don't filter out audible bass.

BTW, I have read the datasheet for the LM308 op-amp a few times and have never persuaded myself that its slew rate or gain-bandwidth are so low as to make a difference at guitar frequencies (up to 5 kHz or so).  The Rat circuit just kinda sounds like a Rat. I think if one wants something that sounds different, maybe a DOD 250/MXR Distortion+ ?

Looked at it in a hurry that's my bad

[Aentons]

JHS has a made a "little discovery " of using the NE5534 chip(I think), which I have heard referred to as the "glass mod". They also state that they make "a few value changes along the way for optimum bass response and smooth silky highs."

https://www.jhspedals.com/products/mod-shop/proco-rat2-pack-rat/

Just saying...

[jimilee]

With all the above changes, we might as well build another pedal that is designed for bass. This is getting complicated. I've played bass for over 30 years. Try not to over think it too much. That's why we play bass, Right?


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[Aentons]

With all the above changes, we might as well build another pedal that is designed for bass. This is getting complicated. I've played bass for over 30 years.

Sorry if I misunderstood, I didn't think we were talking about mods for using it with a bass... That would likely just be a clean blend, which Jack said he didn't want to do.

I do enjoy the exploration of available options so I was just throwing out some info that I ran across to see if it sparked a discussion on an angle that maybe had not been explored to deth 

Sorry, I'll shut up now