Rat, Turbo Rat & LM308

Post by **Doog** » Wed Sep 08, 2010 4:07 pm

HAHAHA

johnnyseven · Post by **johnnyseven** » Wed Sep 08, 2010 5:15 pm

Doog wrote:It reduces the gain by about a third, but improves low-end frequency response as you turn down the distortion dial. A great mod if you prefer medium gain sounds, I'm not sure it really alters the FULL GAIN AHEAD sound, aside from reducing the maximum level of distortion available. I did the mod on my '91 RAT 2 to cop the sounds of my previous modded RAT 2 but preferred having more gain on tap, so undid it.

Either way, it's an easy mod to undo if you cut the resistor in question in the right place, allowing you to reconnect its wires with solder.

Thanks Doog. I think i'm going to give it a try as i'm using my rat for mid-gain sounds. Where would be a good place to cut the resistor to reverse the mod should I decide I don't like it? As i've said before i'm a total dingbat when it comes to electronics etc.

Bill Oakley · Post by **Bill Oakley** » Wed Sep 08, 2010 5:28 pm

If you clip it, your probably not going to be able to repair it without replacing it. You can desolder one leg and pop it out. That's about the only way to do it so you can reverse it. I personally would take the resistor out and replace it with a B1K pot so you can adjust it to taste. You could also do the same thing with the 560 ohm to ground and have full control over the frequencies.

johnnyseven · Post by **johnnyseven** » Wed Sep 08, 2010 5:48 pm

The inside of my Rat looks like this, nicked from DIY Tube Amp Page site:

The resistor on mine looks different (colour) though, but I guess it's the position that needs to be correct not the colour of the resistor.

Me trying to fit a pot = headache + most probably failure + destruction of my pedal

sp3k · Post by **sp3k** » Wed Sep 08, 2010 6:01 pm

Instead of just cutting it you can add an extra on/on switch for having both sounds. I did it and i'm noob when it comes to soldering.

BTW, if you think it has low gain in ruetz mod try adding a boost before it, sounds really good, much better then stock sound, at least for me.

Bill Oakley · Post by **Bill Oakley** » Wed Sep 08, 2010 6:09 pm

johnnyseven wrote:The inside of my Rat looks like this, nicked from DIY Tube Amp Page site:

The resistor on mine looks different (colour) though, but I guess it's the position that needs to be correct not the colour of the resistor.

Me trying to fit a pot = headache + most probably failure + destruction of my pedal

Actually it's the bands on the resistor that are the most important. They tell you the value of the resistor. If your board layout is EXACTLY like the one pictured, it's probably the right one. There are a bunch of different boards used in the Rats so make sure you clip the right resistor. A 47 ohm resistor should have yellow-violet-black (and probably gold but that doesn't matter) bands on it.

C'mon! Replacing a resistor with a pot is one of the easiest things to do and probably well worth it in this instance.

johnnyseven · Post by **johnnyseven** » Wed Sep 08, 2010 6:17 pm

My Rat has exactly the same out lay as the one in the picture, it's just some of the components look different - when I had it modded with the metal can LM308 I think they changed so of the other components too. However the resistor in that position has bands that are black, purple (or violet) and yellow so it must be the right one.

How easy is it to fit the pot? Can you send instructions including what components I need to buy?

Bill Oakley · Post by **Bill Oakley** » Wed Sep 08, 2010 7:45 pm

There's a lot of room in Rats for pots and switches.

You need:
B100K Potentiometer
2 pieces of wire
Soldering iron and solder
Some solder removal braid will make it a little easier but not necessary
Drill with a drill bit
Knob

Here is the step-by-step:
1. Decide where you want the pot but don't drill yet. Make sure it all works before you start drilling holes (My Rule #1).
2. Remove the resistor.
3. Cut two pieces of wire long enough to go from the resistor spot to where you want to put the pot.
4. Solder one wire into each hole where the resistor was.
5. Solder one wire to the middle lug of the pot. Doesn't matter which one.
6. Solder the other wire to an outer lug of the pot. Test it out. If it works backwards for you, remove the wire from the outer lug of the pot and put it on the other outer lug. Test it out again to make sure it's working properly. If your circuit board or jacks ground to the enclosure, put it back in the enclosure to test or you are going to get a lot of buzzing.

Note: It's good practice to jumper the middle lug of the pot with the unused outer lug. I would do this. If the pot ever fails, you won't loose signal.

7. Drill your hole. Mount the pot and put on the knob.
That's it!

johnnyseven · Post by **johnnyseven** » Wed Sep 08, 2010 8:08 pm

Thanks Bill. It all sounds pretty easy to me apart from the soldering part, my soldering skills stretch as far as fitting pickups or soldering capacitors into guitar electronics - but my style is messy to say the least. It's the need to be precise and clean with my soldering which will be the difficult part. I might do the Ruetz mod first and if i'm feeling brave give this a go at a leter date.

Bill Oakley · Post by **Bill Oakley** » Wed Sep 08, 2010 8:13 pm

If you don't practice, you'll never learn!

Anyway, no problem. I just did it to one of my Rats and it's well worth the pot. Removing the resistor was ok but having the pot blows it away. You get stock Rat, Reutz Rat and everything in between.

johnnyseven · Post by **johnnyseven** » Wed Sep 08, 2010 8:47 pm

Having looked at the pedal I was thinking that instead of removing the resistor totally I could snip the wires right at the resistor end and solder the new wire to these pieces of wire. I would find soldering onto the ends of these wires easier than to the circuit board itself as there would be less chance of the solder spilling over onto other components. Does that sound like it would work to you?

Also I don't really want to add another pot onto the outside, would it be possible to get a B100K trimpot and leave this inside the pedal?

Bill Oakley · Post by **Bill Oakley** » Wed Sep 08, 2010 9:09 pm

johnnyseven wrote:Having looked at the pedal I was thinking that instead of removing the resistor totally I could snip the wires right at the resistor end and solder the new wire to these pieces of wire. I would find soldering onto the ends of these wires easier than to the circuit board itself as there would be less chance of the solder spilling over onto other components. Does that sound like it would work to you?

Also I don't really want to add another pot onto the outside, would it be possible to get a B100K trimpot and leave this inside the pedal?

Yes and yes. The trimmer is wired up in the exact same way only you wouldn't need a knob.

johnnyseven · Post by **johnnyseven** » Thu Sep 09, 2010 9:33 am

I found these - http://www.bitsbox.co.uk/resistors/presets.html - would the 100K vertical or horizontal trimpots fulfil my requirements? I thought i'd try both to see which fitted inside better.

Can anyone suggest any better ones from another supplier (UK based)?

Bill Oakley · Post by **Bill Oakley** » Thu Sep 09, 2010 1:56 pm

That should work. A lot of people use this place: http://www.maplin.co.uk/Module.aspx?Mod ... Code=WR40T

I made a mistake in my post about what you need. I wrote B100K. You need 1K. I was trying to do two things at once and messed up.

johnnyseven · Post by **johnnyseven** » Thu Sep 09, 2010 2:01 pm

Thanks for that. Maplin have shops all around central London, I can go and pick one up on my cycle home.

johnnyseven · Post by **johnnyseven** » Thu Sep 09, 2010 7:23 pm

So I did the Ruetz mod and I like it. It does however vastly reduce the variation in gain and sounds from the pedal, the distortion dial is pretty much useless before 12 o'clock. However the sound it does give I like. I also bought a trimpot on my way home from work and will probably try and fit at some point when I have time to see what it can do but at the moment i'm happy.

cobascis · Post by **cobascis** » Fri Sep 10, 2010 12:33 am

James wrote:
Doog wrote:It reduces the gain by about 15%...

Oh and I as well performed the reutz and undid it. It does sound great, but I like a lot of gain on tap.

Bill Oakley · Post by **Bill Oakley** » Fri Sep 10, 2010 12:39 am

That's why making this an external pot is better. You get Reutz, normal and everything in between.

Post by **Doog** » Sat Sep 11, 2010 5:05 pm

Doog wrote: The '92 RAT 2 I bought off Mr Winter indeed sounds very different to the current production (Russ from CAUTIONHORSES has one based on my recommendation and it's pretty nasty)

I take this back. Here is my working:

[youtube][/youtube]

Taylor704 · Post by **Taylor704** » Sat Sep 11, 2010 7:01 pm

I never really got the mojo for the LM308 because to me they always sounded pretty damn similar.

Saying that, mine was alright, but I don't think RATs are the right pedals for me. They've just got too much gain for what I use and doing the Reutz mode made mine a bit muddy which got so annoying after a while. Some people can make theirs sound amazing, but I just never got what I wanted from mine. Replaced it with a Marshall Drivemaster and it sounds fucking amazing through my AC30