rat clipping section, what if I put LED's instead of diodes?

[Xavier]

I have just purchased a Rat 3 (one of the new ones in a smaller enclosure). I want to tweak it a little bit, and I'm just wondering what would happen if I put 2 LED instead of the 2 Si clipping diodes, soundwise....

[Ed G.]

You'd have the Turbo Rat:
http://www.diystompboxes.com/pedals/ratmod.gif

[smoguzbenjamin]

The distortion would sound different... since LEDs have a higher forward voltage, your signal would have to be bigger to clip it... and they add a couple of different harmonics too - absolutely not sure bout that though...

Basically, it's a completely different story

[Mark Hammer]

1) You'd have more output level.

2) You wouldn't be able to get nasty distortion.

3) You would have to play really hard with the gain cranked to get distortion much of the time.

[Gus]

The rat with leds sounds good with bass guitars.  I put a switch in a turbo rat to switch the leds to 1n4148s.  With the signal level from a p or j passive bass the leds tend to sound "better",  guitar the 1n4148s sound better.

I like to install tant caps for all the Als except the PS bypass in rats.  I have read the first ones used tants.

[petemoore]

...or Type
 what 's in the diode clipping section?
 By changing the config of diodes using two seriesed where there were 1<way and 1>that way, or if it already has 4 taking two out so theres 1<way and 1>that way will  change the sound of it.

Feedback loop          diode>    diode>          OA output
                              <diode   <diode
  -------------------or------------------------
 FB Loop         diode>                       OA out
                     <diode
 .........................................................
 Try Ge's and Si's
 If your rat [cause I forget] is a signal output to ground clipper...substitute 'FB LooP" for signal path near output [where diodes connect]
 and OA output for ground.
 Then read all about this stuff at AMZ and other great stuff like warp and saturation control.
 There's a Mods page around this site somewhere, you'll find clipping info you can use there.

[Xavier]

Thanks for the answers

So far I have substituted only one of the diodes by a LED, and it seems to sound a tad clearer and punchy, which is perfect for me, as the stock setting is a little too dense and mushy .

BTW the Turbo Rat was supposed to have double the gain of the Rat II, it's only the LED's that makes the difference?

Any other suggestion?

[brett]

You can double the gain by switching from a 250k gain pot to a 500k, but why not go all the way and make it a 1M ?

Oh yeah :twisted:

[Xavier]

You can double the gain by switching from a 250k gain pot to a 500k, but why not go all the way and make it a 1M ?

Oh yeah :twisted:

Is that the EVIL RAT MOD? LOL

I'll try it, not a hard mod to do.......

[Xavier]

1) You'd have more output level.

2) You wouldn't be able to get nasty distortion.

3) You would have to play really hard with the gain cranked to get distortion much of the time.

Here's what I'm gonna do today. I will put both LED's but I will switch from the 250k gain pot to a 500k gain pot. I hope this compensates. Anyway, to me the maximum usable gain before entering the fuzz territory is around 12:00 on the gain pot.....

[Xavier]

So what I did finally...........

I tried all kind of diodes and combinations....

LED/LED. Less gain, less push, less of everything.

LED/Si. To my ears, almost the same as with 2 Si.

LED/Ge. A little grittier than with 2 LED. Still not punchy, but buzzy

nothing / LED. A big volume hump, good as a booster, little gain.

So what I ended up with?...*drum roll*.............

Si/si. Yes. Stock version. Much better sound to my ears. More gain, more muscle to the sound, more attack. After almost f*****g the PC board, I ended up where I started.

It seems I tend to dislike mods. It happened the same to me with the DS1. Maybe that means the original designers have ears too :roll:

The only thing left to do is adressing that mushy and flabby pick attack. I want more attack and probably less bass frequencies going into the clipping section. I want kind of a "metal rat", if you get what I'm after.....

[WGTP]

Try 2 SI/1 SI.  More even order harmonics and a little more output.  The one I rebuilt had 2 SI/2 SI.

I have found that the rat distorts a lot with no diodes and just the op amp.  

[Xavier]

I will try putting another Si, but I took it to the rehearsal yesterday and I couldn't use more than 1/4 of the gain without entering the fuzz area. This thing is a BEAST

[Torchy]

Any other suggestion?

:oops:
Coat on, taxi waiting ... ...