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I have an Ibanez TS-9, MIJ, silver label. It has the RC4558P chip. How does this differ (or is supposed to differ) from a model with the more "desirable" JRC4558D?

It also has a "brown mod." I read about it on a couple of sites - Analogman for one - but still don't quite grasp what this mod does (as opposed to an 808 mod for example)

Any direction to a site that can explain these appreciated (think effects mods for dummies)

Thanks... ...robert
 

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Excuse my bias on this...I've swapped the ICs and done the brown mod for guys on 2 occasions. The brown mod, as I recall, installed one or two of the older carbon composition resistors in place of the metal films that came in it. To be honest with you, I don't suspect that many people can hear a difference, but I don't buy into the tubescreamer mod hype.
 

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I've always considered mods/upgrades to operate under the law of diminishing returns. Depends on how picky or obsessive you are to get that bit of extra tone/performance. For those of you unfamiliar with the law,... i.e. You buy a $500 guitar and you are 90% satisfied. You spend $250 on new pickups to get it up to 95%. Later you upgrade the bridge, nut and tuners for another $250 to get it up to 97.5%, etc.

I got this pedal used for $80. It already had the mod. All I know, is that I like it.

Oh, and I've upgraded the pups on both my guitars and the improvement was noticeable.- I guess I am somewhat picky/obsessive
 

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"Beware the sales hype!"

Robert1950 said:

I got this pedal used for $80. It already had the mod. All I know, is that I like it.
Here's the REAL scoop!

In the beginning (late 70's or so) Ibanez invented the tube screamer. It was based on an IC called a dual op amp. These devices look like any other 8 pin IC, like a little black rectangle with 4 pins along two parallel sides. The pinout connections are standardized so that there are a number of dual op amps made that have different characteristics that will fit in the same position. More on this later.

Anyhow, the pedal was a big hit but like most new innovations after a few years it was "old hat" and was discontinued.

Fast forward a decade or so. The demand for used tube screamers had gone crazy, especially when it became known that SRV had used one. So Ibanez re-issued the pedal. They built it EXACTLY the same! Even some of the guys assembling the pedals were the same.

Yet very soon the word was out that they did NOT sound the same! Sales tanked.

Ibanez was mystified. The first impulse was to blame it all on the musicians. Mojo crap, hype, mass hallucinations or whatever. But when big name artists with VERY good ears passed the blindfold test they knew they were dealing with something real.

To make a short story long, there was a problem! The IC was TOO good!

You see, IC's were a relatively new electronic device when the pedal was first released. The 4558 was made by a number of different manufacturers. Each would keep the generic number but put their own prefix on it. So if Raytheon made the IC it was marked "RC4558". The winning bidder for the production order of the pedal was the Japan Radio Company, who marked their chip as "JRC4558". Same device, just a different manufacturer.

Again, hit the fast forward button. By the time Ibanez re-released the pedal IC making technology had drastically improved. The production lines had gone through several generations of IC making machines. Specs on the 4558 had gotten better and better. By the time Ibanez was ordering them again the device had gotten much more "hifi" and distortion free.

As I've written and said a zillion times, who the heck wants a hifi sounding guitar ANYTHING for rock and roll? The new IC's didn't distort quite the same when overdriven as the old ones. The difference wasn't super obvious but good ears could hear the difference. I can't really hear it (too many years of George Thorogood on 11) but players have proven it to me in tests.

So what could Ibanez do? If you're not an IC production engineer you might think they could just make the 4558 the old way but like many things it's just not that simple. IC making machinery costs a zillion dollars. The IC's themselves usually cost just pennies. So you have to make them by the boxcar full or not at all. You have to run 50,000 pcs or so just to grease the machines!:tongue:

The old machines had long been scrapped. The number of IC's Ibanez could order would be a spit in the ocean for the number needed to even think about re-making the old style machines. Ibanez sucked it up and no longer claimed in their ads to be exactly like the old pedals. They simply said "Here's our tube screamer again! Doesn't it sound great?"

Well, maybe the ads were a little more sophisticated than my example but you get the drift. Besides, the pedal does sound great! Maybe not precisely the same to a few folks blessed with "bat ears" but so what? Is the intent to precisely clone the old sound or simply to sound good? Just because you have SRV's exact gear won't help you sound just like him without a helluva lot of practise and a healthy dose of talent given from the gods. (Or maybe a midnight deal at the crossroads...)

Meanwhile, this situation had opened the door to the mojo market. Guys were placing ads in magazines and today on the Net offering "The ORIGINAL JRC4558 for your Screamer!" Since the rest of the pedal was exactly the same the idea was that you could just simply swap the new IC for the old and you'd be happy.

I never bought into this at all. I was there selling IC's in the industrial production world from the late 70's to 9/1/1. I know how things work in that market. Where would these IC's have come from? A dusty cache on the back shelf of an electronics part distributor? Not one of them worth their salt would have been so sloppy about inventory. Besides, the 4558 was always in demand for industry in a zillion applications. The box would simply have been emptied of the old parts and constantly filled with newer parts, for all those years.

Now, I'm not accusing anybody here :tongue: but one thing I do know is that although making the 4558 the old way would require impossibly huge volumes it would require only a modest sized order to get them to change the marking on the IC! It's done all the time. Eastinghouse Electronics would design in a standard part but ask the part manufacturer to put their in-house inventory number on it instead of the publicly listed catalogue number.

Changing the ink is cheap! Anybody could afford to order a new IC with the mojo JRC4558 number. To make things worse, the Japan Radio Company is still around. They had years ago changed their name and prefix to NJM instead of the old JRC but you could presumably order the IC from the same company and ask for the old marking.

So cynical old me is very suspicious of these mojo advertising claims.

I do the mod here at my shop all the time, but with a different wrinkle. I'm always scouring thrift shops for tube junk and keep an eye open for old telephone answering machines or whatever from the late 70's. I buy 'em for a couple of bucks and when I rip 'em open at home I find that 2 or 3 times out of 10 there's a real JRC4558 inside! I carefully remove the IC and put it away.

I never have a lot around but usually I have a couple. When I make the change I put a small socket for the IC so that you can change it easily without any de-soldering.

Some fans try other dual op amps like the TL072 in the pedal. If you're not all hung up about the original tone you can get some cool new tones this way. Experimenting is fun, anyway.

As for the "brown mod", the idea of using a couple of old fashioned carbon comp resistors to me is just plain, unadulterated crap! I can think of absolutely no technical reason why this would work and all kinds as to why it would make no difference. It's just superstition and gullibility, nothing more.

It's like buying a "mojo hand". Madam Eureka has a production line turning out these phonies behind her shack in the bayou, if she hasn't subcontracted out to China.

Besides, every musician knows that the Eugene Martone (the Karate Kid) has the last true mojo hand in all the world...:rockon2:
 

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Discussion Starter #5
God love y' Bill.
 
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