New ProCo Rat vs. old: what's the difference?

  • Thread starter Thread starter diggy_dude
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Changing IC's, I have a hunch the bias on the IC has to be compensated for. No one talks about that, and I can't prove anything. But my theory is that if you compensate for that, it should sound the same. It's the diodes that clip and make the sound. Germanium, silicon, LED's, a mixture, whatever. The op amp is only there to provide enough gain to make the diodes work.
I had a 70's Japanese Memphis distortion box that was a clone of an MXR Distortion+. They biased the 741 differently than MXR, even though it's still a 741. I think MXR did a 50/50 split off of the +9VDC with a pair of 1Meg resistors. Memphis used 100K and 150K if I remember rightly. I didn't like the Memphis, and just rebiasing the 741 made it sound more like a Distortion+. Well, the 1N270's have a sound. The Distortion III has buffers and 1N4148's. Blech. I can't remember what Memphis used. 1N4148's? Either way, LED's made it sooooooooo much better. And that crappy 741 stayed.
 
It's true that there are a bunch of things affecting the sound. If younare building your own or modding it is nice to experiment and see what makes different sound changes.

If youre not modding, buy an old rat or get the Keeley mod to a new one.
 
I'm thinking I may skip the Rat rigamarole altogether and go with an MXR Distortion III, if I decide I absolutely must have a distortion pedal.
 
cool. I haven't played one, but they sound pretty cool from what I've heard.
 
there's SO many great pedals out there. Just hundreds of the things and I see a lot of 'em I'd like.
 
diggy_dude said:
Fascinating. So if the op amp isn't responsible for the difference, what is? Filter caps? Diodes? Pot tolerances?
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I don't buy it. I know the "technical" side says there should be no difference, but there is HUGE difference sometimes. Just try swapping opamps in an old API preamp and tell me they make no difference. Or on a simpler level, try swapping opamps on a TS and listen to the difference.

But, yes all of those components and their values can make a very big difference. Pot tolerances can control how strong an effect is and how much each little turn of the pot changes it. Capacitors can make a big difference based on value and the type of cap used (expensive doesn't mean better though, sometimes cheaper components like ceramic caps can sound really nice).

Basically a pedal is an electronic circuit, so any change to the circuit will result in a change in sound. some changes are more pronounced than others, and some changes are so miniscule they don't make any kind of noticeable difference.
 
I'm gonna have to go with Mr Coleman here. I see FAR too many articles in my audiophile mags by writers whose opinions I have come to respect about the improvements made in pre-amps by using different opamps to believe there's no difference between any of them.
 
Again, I don't know, but I would never say out loud that there has to be a difference, without something other than "try swapping opamps in an old API preamp and tell me they make no difference". And, I wouldn't say there cannot be a difference and just chalk it up to "I can't hear a difference".
Is it slew rate?
  1. RC4558 = 1.1V/us
  2. TLC2272 = 3.6V?us
  3. LM833 = 7V/us
I don't know. Is it biasing? I don't know. But in the 'test' demonstrated above, different slew rate IC's didn't seem to make that much difference. But this is a distortion device, and not anything else. The diodes will clip any gain the IC has given, and keep the output at .3VAC for Ge diodes and .7VAC for silicon. So the IC doesn't have to do anything other than provide the diodes something to work with.
Ah, who am I kidding? I haven't got a clue. I just thought the video above would open a few eyes, rather than make everyone squint even harder to try and 'hear' IC's. Power to you.
 
ranjam said:
Again, I don't know, but I would never say out loud that there has to be a difference, without something other than "try swapping opamps in an old API preamp and tell me they make no difference". And, I wouldn't say there cannot be a difference and just chalk it up to "I can't hear a difference".
Is it slew rate?
  1. RC4558 = 1.1V/us
  2. TLC2272 = 3.6V?us
  3. LM833 = 7V/us
I don't know. Is it biasing? I don't know. But in the 'test' demonstrated above, different slew rate IC's didn't seem to make that much difference. But this is a distortion device, and not anything else. The diodes will clip any gain the IC has given, and keep the output at .3VAC for Ge diodes and .7VAC for silicon. So the IC doesn't have to do anything other than provide the diodes something to work with.
Ah, who am I kidding? I haven't got a clue. I just thought the video above would open a few eyes, rather than make everyone squint even harder to try and 'hear' IC's. Power to you.
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You may never say these things out loud, but I will, I can hear a difference...I don't know what it is, biasing may play a roll in the whole overall sound, but I can hear a difference between one type of IC and another.

I won't pretend to know enough about the technical side of things, I really have no clue. In my unscientific swaps of IC, rebias of pedal/preamp, and listening tests I can hear a difference. That's all, no need to make this a bigger deal than it has to be. Some people claim there is no difference, others claim there is a huge difference. Listen for yourself and choose what you like.
 
aaronmcoleman said:
You may never say these things out loud, but I will, I can hear a difference...I don't know what it is, biasing may play a roll in the whole overall sound, but I can hear a difference between one type of IC and another.

I won't pretend to know enough about the technical side of things, I really have no clue. In my unscientific swaps of IC, rebias of pedal/preamp, and listening tests I can hear a difference. That's all, no need to make this a bigger deal than it has to be. Some people claim there is no difference, others claim there is a huge difference. Listen for yourself and choose what you like.
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there ya' go. If you can't hear a difference, then for you there IS no difference ........ if you can, then there is ... simple as that.

For example, I hear a difference between some cables. There are those who say that can't be and those who say it's true. There are scientific articles about why there can't be a difference and other equally sciencey articles about why there is.
Ultimately I decide based on what I hear.
Sometimes on the boards I get challenged to put up soundclips and prove my point.
I don't bother because I don't care what anyone else hears or believes. I hear it and my ears are really the final decider for things that I'm gonna be using.
This is similar .
I had a friend who recently changed the Opamp is his TS9 to make it more like a ts808. He says it made a substantial difference. I didn't hear it beforehand so I have no opinion but he's a skilled player with good ears. It's hard to simply discount his opinion.

However ..... someone gave me a collection of Guitar Player mags from the last 35 years or so and there was an interview with the guy that designed the TS808 and TS9.
He said there was absolutely no difference between the two other than they put two kinds of power jacks on the circuit board so it could go into either chassis.
:)
So ...... when there's so many people swearing there's a big difference between the two and the designer saying there isn't ....... what do you do with that?
 
Well, there is a very obvious difference between the sound of the old and new Rat pedals in the YouTube shootouts I've seen. So the question is: are the people who make those videos setting the knobs in a way that will guarantee a fair, unbiased comparison?
 
diggy_dude said:
Well, there is a very obvious difference between the sound of the old and new Rat pedals in the YouTube shootouts I've seen. So the question is: are the people who make those videos setting the knobs in a way that will guarantee a fair, unbiased comparison?
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that absolutely becomes a big factor. It can be difficult to get the exact same results when micing stuff up in your own studio. Once you start having various people with their reviews and recording processes it quickly becomes meaningless because you have no frame of reference.

As I said and always say ..... ultimately it should come down to what YOU hear.
I never change my position on sound because of someone else saying blah blah blah. I hear what I hear and I go with that ...... always.
 
True, but I would have to buy both pedals to do my own comparison. The idea is to find out before I spend any money.

Anyway, thanks for the views and different perspectives on this. :)
 
diggy_dude said:
True, but I would have to buy both pedals to do my own comparison.
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well maybe ..... but there's a way around that ... if you can find someone with an old pedal you can borrow....... buy one from someone like Musicians Friend or Sweetwater ..... borrow the old one .... make the comparison and then if you prefer the old one ..... there's a 30 day return for the new one so you could send it back.
 
I have an old Rat (made around 90's) and new one (3 years old) and I must say that the difference is a little bit overstated. At home playing on 15W amp you wont feel the difference, I haven't done bigger research, maybe at studio conditions I could tell more. Actually it is very interesting subject, a little bit kind of a myth (or maybe not) and the price difference between the old and new Rat is pretty obvious. Maybe I'll find a motivation and make some sound clips with line in and mic recordings to finally research these statements
 
On the technical side, people always talk about old rat vs. new rat, but there are actually three rats: the original rat, the USA rat-2, and the Chinese rat-2. (Read on - there are actually 5.)

Most people know about the original vs. rat-2 discussion. There were minor changes to the actual circuit when the rat-2 was released (which is probably why they renamed it). But what many don't know is that when they moved production of the rat-2 to China, they reverted to the original rat circuit.

The original to rat-2 changes in 1988 were partly minor changes to the actual audio circuit, but mostly the addition of a true bypass capable LED indicator circuit. A new PCB was introduced for this, which was also capable of implementing the orginal rat circuit. The last issues of the small-box black-face original rat used this PCB, as well as the rat-2 and turbo-rat. Over time, other rat models were released, and therefore production changes occurred. Jumping ahead to 2002, the deucetone rat was released, and it featured a 3PDT footswitch (by then plentiful and cost-effective) to handle the indicator LED, thereby eliminating the need for that portion of the rat-2 circuit changes. The deucetone required a new PCB to allow the position of the footswitches to be at the sides of the PCB (as well as the center), and this PCB was designed using the original rat circuit. It is easily identifiable by the three large holes for a footswitch. This PCB was eventually carried over into production of all other rat models including the USA rat-2, turbo rat, and the 2004 you dirty rat.

Side note: There was another PCB that was introduced in 1995 and was capable of implementing either the original rat, the rat-2 or the turbo rat circuit (slight difference from rat-2, not just the clipping diodes). It was called the Multi-RAT and was used in all production models at that time - the rat-2, turbo rat, and the vintage rat big-box reissue. Note that this PCB did not introduce any circuit changes, it just simplified the production process.

When production of the rat-2 moved to China, the same 3PDT switching and original rat circuit was used. Note that it has been reported that the filter control cap is a slightly different value than the original, so it isn't identical, but that is arguably not a sonic difference only a difference in the range of the filter control.

Keep in mind that the other big technical change happening is the op-amp change from an LM308 to an OP07, which started towards the end of USA rat-2 production resulting in two or three different USA rat-2s - probably three since it appears that the LM308 op-amp was used in the early days of the new PCB - the switch to the OP07 appears to have started sometime in 2003 or early 2004.

If you're still following, this means that apart from the op-amp, the Chinese rat-2 is more like the original rat than the early USA rat-2. It also means that there are probably a small number of USA rat-2s with the new PCB and an LM308, making them actually pretty much identical to the original rat circuit-wise.

So, the old rat vs. new rat discussion is rather complicated. This could explain why some people do a comparison and hear little difference, and others hear a big difference.
 
I'm not reading any of this thread, so I'll just ask.....what's considered an old ProCo Rat?
 
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