Proco - Rat ( Keeley modded )

analogguru · Post by **analogguru** » 08 Feb 2008, 14:05

guts:

http://i24.ebayimg.com/05/i/000/d8/8c/1272_3.JPG
http://i10.ebayimg.com/03/i/000/d8/8c/1c42_3.JPG
http://i20.ebayimg.com/05/i/000/d8/8c/37ee_3.JPG
http://i12.ebayimg.com/07/i/000/d8/8c/2641_3.JPG
http://i2.ebayimg.com/03/i/000/d8/8c/419f_3.JPG

interesting the footswitch-assy.

analogguru

madbean · Post by **madbean** » 08 Feb 2008, 14:27

That is pretty slick. I like that better than mounting the entire PCB upside down and directly attached to the 3pdt.

analogguru · Post by **analogguru** » 08 Feb 2008, 14:33

The same 3-way mode for a vintage rat:

http://i9.ebayimg.com/07/i/000/d8/8b/0dbb_3.JPG
http://i13.ebayimg.com/07/i/000/d8/8b/1370_3.JPG
http://i9.ebayimg.com/06/i/000/d8/8b/2bba_3.JPG
http://i2.ebayimg.com/03/i/000/d8/8b/267e_3.JPG
http://i4.ebayimg.com/06/i/000/d8/8b/32e2_3.JPG

analogguru

Dirk_Hendrik · Post by **Dirk_Hendrik** » 08 Feb 2008, 16:49

What's the reason for mounting a 3pdt in a Rat in the first place??

analogguru · Post by **analogguru** » 08 Feb 2008, 16:53

Dirk_Hendrik wrote:What's the reason for mounting a 3pdt in a Rat in the first place??

I think this is performed by ProCo ?

analogguru

soulsonic · Post by **soulsonic** » 08 Feb 2008, 21:34

analogguru wrote:
Dirk_Hendrik wrote:What's the reason for mounting a 3pdt in a Rat in the first place??
I think this is performed by ProCo ?

analogguru

I think the 3PDT footswitches are a recent change in the ProCo. Before, they always used DPDT with the FET to switch the LED - so of course, with that circuit the 3PDT would be pointless. It looks like maybe Keeley would change from the DPDT to 3PDT and remove the FET switch, probably just to make it look like he did more work "redesigning" the circuit than just swap the opamp, add the switchable clippers, and maybe change a couple values. He swaps the power jack too - which is probably a good idea for anyone who uses the standard 2.1mm coaxial setups.

Dirk_Hendrik · Post by **Dirk_Hendrik** » 08 Feb 2008, 22:21

soulsonic wrote:Etc Etc blablabla....whocaresanywayintheend

Soul,
just checked,
Your site is getting more enjoyable by the day!

soulsonic · Post by **soulsonic** » 08 Feb 2008, 22:33

I really love Wordpress!!!

Bernardduur · Post by **Bernardduur** » 12 Feb 2008, 18:26

What I can spot

The Keeley mod involves:
- Replacing the opamp with a LM308, metal can version (maybe not in the LM308 chip equipped versions)
- Replacing the 0.022 uF in and output caps with other values / versions?
- Replacing the cap across pin 1 and 8 of the opamp with a 50 pF cap
- The three way switch switches only one side of the diode clipper
my guess:
Switch up = si diode + LED in series
Switch down = si diode
Switch middle = no connection

Any stuff known on the values of the caps?

okamo · Post by **okamo** » 13 Feb 2008, 06:43

http://sakuratan.ddo.jp/uploader/upload.cgi

[date70498.zip] keeley rat 1468 2008年02/13(水)15:32

The image was set up in the above-mentioned.
Please continue your favors toward English too much though it is not
in good.
Care always becomes it.

soulsonic · Post by **soulsonic** » 13 Feb 2008, 07:11

okamo wrote:http://sakuratan.ddo.jp/uploader/upload.cgi

[date70498.zip] keeley rat 1468 2008年02/13(水)15:32

私はダウンロードを受け取った。

Bernardduur · Post by **Bernardduur** » 13 Feb 2008, 07:27

okamo wrote:http://sakuratan.ddo.jp/uploader/upload.cgi

[date70498.zip] keeley rat 1468 2008年02/13(水)15:32

The image was set up in the above-mentioned.
Please continue your favors toward English too much though it is not
in good.
Care always becomes it.

Cool pics!

So, addition to the above:
- cap before clippers (was 4.7 uF) = 10 uF
- Input cap = 220 nF
- cap before FET = 68 nF
- output cap = 47 uF

ieatyouforbreakfast · Post by **ieatyouforbreakfast** » 14 Feb 2008, 00:19

looks like i'll have to try both keeley and soulsonic mods then.. sigh..

i'm gonna have fun with diode switches muahahah.

[/img]

MB-1 · Post by **MB-1** » 14 Feb 2008, 13:56

I noticed a few of the big name modders (keeley) are using china rats..any difference with these compared to usa version.

ryanuk · Post by **ryanuk** » 08 Jan 2011, 21:27

Resurrecting an old thread here!

There has always been something about RAT pedals that I like but I always found them so damn hard to dial – especially the filter! They always sounded a little thin and woofy to my ears. I realize that this is the way they were intended to sound to a degree, but I always envisaged that it could be improved. Videos on you tube featured much better sounding rats!

I stumbled over this thread a while ago and had a bash at Rob Keeley’s mods, as well as a few others I’d found on the net.

I mapped the circuit on breadboard and spent an evening tinkering with different values.

Tonight I built up a PCB and mounted in a pedal. I'm floored with the results

. Rich, thick, oodles of distortion. No woofy-ness. And a VERY usable filter.

Here’s a list of the subs I made. I’ll use the part numbers from the schem on Analogguru’s site.

C1 – 220n
C2 - 47uf
C8 – 10uf
C7 – 47pf
R10 – 22k
C11 – 10uf

I also played around with the diode clippers, adding in an LED, using 2xLEDs/Ger, but I kept coming back to 2xSil. No switches. Simple.

The substitutions that made the most sonic impact was C1 and R10. C1 to 220n (Keeley mod) made the sound a lot fuller; changing R10 to 22k gives a fatter sound and more usable filter. I tried 47K at first but that was just too dark. Not sure electronically what I doing by changing R10 – it does alter the filter range and over bassy-ness of the circuit.

The other subs just seemed to give a better quality sound. Anyhoo, just thought I would share my findings. Perhaps someone else can also find these mods useful.

I really really like this circuit now though. I urge other non-RAT fans to try these mods.

Oh yeah – forgot to mention – I’m not even using an LM308!! Im using a OP07DP. I found there is VERY little between them. The LM308 is slightly quiter – on very slightly mind. The OP07DP is a little more brash or “rattier”, which I like!! The LM308 is no holy grail!

Bernardduur · Post by **Bernardduur** » 09 Jan 2011, 22:17

Nice! I'll try that!

TheLemon · Post by **TheLemon** » 09 Jan 2011, 22:59

Here's some mods you can do to get a BJF "Dyna Red Dist"-esque Rat:

I know, in doing ALL of the mods you might as well build a Dyna Red but this is for those who want to do either a few or most of them to just get you closer

Greg · Post by **Greg** » 10 Jan 2011, 00:50

TheLemon wrote:Here's some mods you can do to get a BJF "Dyna Red Dist"-esque Rat:

I know, in doing ALL of the mods you might as well build a Dyna Red but this is for those who want to do either a few or most of them to just get you closer

Just a note.. reversing C8 and R9 will have no effect, so you can save yourself the trouble of that one.

Also R6 will have negligible effect and C5 is just there as an RF filter, so a good idea to leave it IMO.

It really needs 2 LEDs across the feedback loop to make it like a Dyna Red.