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JRC4558 myths...

Discussion in 'The Stomp Box' started by 11 Gauge, May 23, 2007.

  1. 11 Gauge

    11 Gauge Doctor of Teleocity

    Mar 21, 2003
    Near BWI Int'l
    Do folks still believe that the JRC4558 chip is the superior sounding Tube Screamer chip?

    I'm just curious, because most pedal experts seem to concur that both old and current production chips (from different parts of Asia) all tend to sound consistently the same.

    Are the misinformed still spending 30 bucks or more for a "NOS" chip, and 2 "brown sound" resistors?

    The 4558 was chosen by Maxon/Ibanez for it's super low cost. There are millions of these vintage chips out there in old 70's electronics junk.

    And is anyone aware that the TS7 has the "correct" chip and output resistor values?

    It's amazing how some of these falsehoods prevail. I'm just wondering where things currently stand. What have y'all overheard at the musician's watercooler discussions?

  2. bo

    bo Friend of Leo's

    Mar 17, 2003
    Arlington, VA
    I didn't overhear anything. I sent Analogman my TS-9 several years ago and had him replace the chip and beef up some weak spots with no other mods and it came back as he described: better. YMMV.
    uriah1 likes this.

  3. scooteraz

    scooteraz Tele-Afflicted

    Apr 17, 2007
    Peoria, AZ
    I know I read something recently about the 4558 that even when the TS was in original production, there was no single vendor. But I beleive the old JRC version is the holy grail of some (even though the actual chip in some of the originals may be made by others).

    I guess there might be some difference ascribed to how a chip is manufactured, but I agree that if all you do in a dozen identical pedals is scramble the 4558s around by manufacturer, then had various guitarists play them, it is unlikely that 99% of them would be able to tell the difference consistantly. And, of course, this is because they all meet the same specifications.

    I put this in the same piles as some of the capacitor, resistor and conductor stuff floating around. I think the high end stereo guys, in particular, have been suseptable to this sort of pseudo-scientific clap-trap.

    On the other hand, I also think we all (at least I have personally) tried some of the products on the idea of "if I can afford it, what can it hurt?" I would love to have an amplifier with oil-paper caps just to see, even though I know that years ago NASA did studies and found that there was no difference in capacitor performance due to construction if they had the same parasitic losses. The reason a carbon comp resistor sounds "better" than a film resistor is the additional noise it adds to the circuit. We have all gotten used to that noise, so it sounds better.

    Back to the 4558, I think that people are just applying NOS ideas to the chips like they do tubes. However, I think the nature of how silicon works vs. thermionic valves does not lend itself to such a comparison. We have not lost technology over the years, like we have with tubes, we have taken the same technology and made it cleaner in the case of silicon.

  4. 11 Gauge

    11 Gauge Doctor of Teleocity

    Mar 21, 2003
    Near BWI Int'l
    From Analogman's website:

    "...Also people have asked about chips on ebay that are being sold as "New Old Stock" TS-808 JRC4558D chips. If you want a JRC chip for a project, get a new chip from Steve at Small Bear Electronics who sells them cheap (sorry we dont have time to sell chips or small parts)."

    "...Early TS-808's have the Ibanez (R) "trademark" logo which some people seek. There is really no difference, although some of these have a Malaysian Texas Instruments RC4558P chip instead of the normal Japanese JRC4558 chip. I can use this chip in the mod if you would like, or can send both the JRC4558D and the RC4558P chips."

    "...Most TS7 pedals come with the correct JRC4558D chip, so we usually don't have to change the chip in our TS7 mods."

    From Geofex's website:

    "...JRC later changed its name to New Japan Radio Corporation and made parts titled "NJM4558". When you order these, you get parts that are labeled "JRC4558". By all reports, these sound as good as the original."

    "...There is some confusion at present over what is a true or "vintage" JRC4558. Several electronics suppliers list the JRC4558. These are sometimes listed in their catalogs as "NJM4558", but what you get are marked "JRC4558D". By all reports, the current manufacture JRC4558D's sound just as good as the ones current with the manufacture of the original tube screamers.

    "...There were zillions of the real "JRC4558" made when it was current. They are still available in isolated caches of parts, although they can sometimes be hard to find. Does true "New Old Stock" matter? probably not. In addition, the JRC4558D was used in tons of Japanese audio equipment at about the same time, so a junky cheap Japanese stereo or clock radio could have several hidden inside it."

    "...Conversion to TS808 - this seems to be a perennial hot one. Simple... just locate the 470 ohm and 100k resistors on the output buffer transistor, tracing back from the output jack, and replace them with a 100 ohm and a 10K. Bang, instant 808. If you're doing this to a TS 10, short out the 1K resistor leading to pin 3 of the dual opamp as well."

    Now 'fess up - how much did some of you spend for the "right chip" and "brown" mods?

    FYI - I had a JRC4558 as the reverb driver in my old Peavey Delta Blues. I yanked it out and put it in my TS5. I wish I could say that it sounded noticably better (but the TL072 that I put in the amp did!).

  5. mr_hankey

    mr_hankey Tele-Meister

    Sep 25, 2005
    I replaced the two output resistors with carbon film resistors I had laying around, and I just order a couple of (new) RC4558P's for 25 cents a piece.

    I don't think I went overboard with the cost on this one.

  6. 11 Gauge

    11 Gauge Doctor of Teleocity

    Mar 21, 2003
    Near BWI Int'l


  7. kludge

    kludge Tele-Afflicted

    Aug 30, 2006
    The thing is, op amps are actually fairly complicated devices internally, and can have widely varying behaviors for slew rate, noise, etc, while being "rated" the same in identical conditions. Back when my vintage Rat II died and I needed a replacement, I was kind of shocked just how inferior the current production Rats are - and the only substantial difference is the op amp.

    On the other hand, "better" and "vintage" aren't necessarily the same thing, even though they get jumbled together in our sorry little heads. It's a demonstrable fact that the tone quality of 4558 op amps varies significantly. Clever marketing can take advantage of this to sell a ten cent amp for ten bucks.

    What we could all really wish for is that large-scale pedal manufacturers would actually do LISTENING tests on these "identical" parts, rather than just buying whatever is cheapest at the moment.

  8. red57strat

    red57strat Friend of Leo's Silver Supporter

    Oct 4, 2003
    I built a BYOC Screamer clone kit and sold the original TS-9 Tube Screamer that I bought used for $15 in 1984 for a considerable profit with no regrets whatsoever other than the fact that I wished I had sold it back when the prices peaked.

    The old pedal was not superior to the new one in any way, in fact, it was inferior in ways.

  9. scooteraz

    scooteraz Tele-Afflicted

    Apr 17, 2007
    Peoria, AZ
    I decided to look up what I could find from the old JRC 4558 and current production. The data sheets are pretty close. The thing is, even "identical" production is only checked to see if it meets minimum specifications, and if it does, then out the door.

    Guess I need to build a couple of the TS clones, and get a couple of "NOS" JRC and TI chips, then go to Newark and purchase some built by Fairchild and ST Microelectronics, and see if I can set up a "double blind test". See if anyone gets the chips right as they use the pedals. Wouldn't put this issue to bed, but it would be good clean (well dirty guitar sounds clean) fun. Then I will decide if I eat my words and become a "true believer" or if I decide whatever sound we hear from the various chips is only in our imaginations.

  10. kludge

    kludge Tele-Afflicted

    Aug 30, 2006
    If I were to build a Tube Screamer clone (or any other sort of diode-clipper + op-amp pedal), I'd use a sockets to make the op-amps and diodes easily replaceable. Back when I did DIY hi-fi, we saw a lot of complicated issues where things happening outside the audio frequency range had clearly audible effects (intermodulation distortion, for example). So when specs are narrowed to frequency ranges or specific dynamic ranges, I get real suspicious.

    For a point of comparison, think about the huge effect that lead dress can have inside an amp. Change NO components at all, just move some wire around a bit, and you can go from an amp that sounds great to an amp that sounds dry and dead and blows up transformers and tubes - it's all about ultrasonic oscillations. So not even a chip schematic will tell you about things like internal transistor layouts, gate capacitance, and all the other possible points of weirdness.

  11. kludge

    kludge Tele-Afflicted

    Aug 30, 2006
    Oh, and I should add that it's unlikely listeners will "get the chips right" in say, blind testing between vintage JRC and new Fairchild. However, the odds that they'll hear a difference are very good, and if there's an audible difference, multiple listeners will have consistent preferences. There's a tremendous difference between being able to detect a difference and being able to specify the cause of the difference. This is where the double-blind test "scientists" get it wrong, AND their critics get it wrong... the double-blinders may find that people can hear differences that can't be measured, and the critics may find that they prefer the uncool choice over the cool choice in blind testing.

  12. scooteraz

    scooteraz Tele-Afflicted

    Apr 17, 2007
    Peoria, AZ
    What I was thinking of was getting like 3 or 4 samples of each manufacturer. Then just having people say "I like #1 best" or "I like #3" best. Then look at the data and see if any of the following are true"

    1) Folks were consistanly picking one manufacturer as best
    2) Folks were consistantly picking specific chips as best, but the manufacturer is random (somethiling like #1 was a specific TI, #2 was a specific JRC, but as a group no manufacturer was dominant).
    3) Data was completely random.

    In my, admitedly limited, experience in testing op amps, it seemed to me that for a given model, e.g. 4558, there as much variation sample to sample from a given manufacture as there was between manufacturers. I would think this is to be expected, as these are used in applications other than distortion pedals (gasp, the heresy of that last):lol: .

    Like you, I would be absolutely apoplectically stunned if ANYONE could on mere listening say "That is an STM 4558 from 2003", or the ilk, and be consistantly right.

    The issue in high end audio that I have seen is that when specs are equal and EQ's and levels are matched, even "golden ears" have a hard time telling the difference between various components and setups. However, when they are allowed to audition with full knowledge, usually the more expensive / prettier piece is seen as better. I don't know of any "blind" test that went another way...not saying it is not out there, only saying I have yet to see it.

    In any event, what I am hearing you say is that you believe outcome 1 above will occur. My hypothesis is that it will be #3. Until either one of us gets around to actually doing the test (or some other party without commercial interest) we will only have opinion based on purely subjective data.

  13. scooteraz

    scooteraz Tele-Afflicted

    Apr 17, 2007
    Peoria, AZ

    However...internal capacatiance change on the chip is based on manufacturing tolerances. So, chip to chip variation from a given manufacturer would as likely be as different as going to another manufacturer. To get a 3 MHz bandwith requires some pretty small capacitances to not get ringing before that frequency is achieved. Lead dress is GROSSLY larger effect than is the manufacturing tolerances on an IC package like the 4558.

    And IM, I thought the purpose of a TS was to have distortion...not to mention that usually IM is caused by bumping against non-linearities of the circuit, something that occurs on a 4558 orders of magnitude above the hearing frequencies, and therefore less likely to manifested in sub harmonics over 10 octaves away (3 MHz is at least 10 octaves above 20kHz one would expect decreasing effects in each octave)

  14. 11 Gauge

    11 Gauge Doctor of Teleocity

    Mar 21, 2003
    Near BWI Int'l
    Great points made, truly.

    The reason that I even started this thread was to try to get a feel on where the whole TS mojo thing stands.

    I started researching TS's quite a long time ago. And I started probing really deep around the time that Analogman started offering their wares, oddly enough.

    I've noticed 2 profound changes in the last 10+ years:

    1. 4558 'variants' that either weren't disclosed of, or were considered bad, are now considered good. These include the Malaysian 4558, and the NJM4558 which is now stamped as a JRC4558D. It's a little relieving to know that some of the opamp chip gurus were willing to let this out of the bag.

    2. People are building clones and ditching their 'real deals' because they sound better. There is a post above that is proof positive of this.

    But even all of these years later, the mystique around the '4558 still amazes me. You would think that there was all of this R&D done to finely craft this little chip that went into the first 808's, based on all the legend that has been circulating for waaay too long, now. No one either remembers or investigates to find out that the '4558 was chosen because they (Ibanez/Maxon/etc.) were dirt cheap, and there were hundreds of thousands of them produced.

    Saying that the '4558 is the best dual opamp for a TS type pedal is like winning the lottery the very first time you play. There are over 40 different dual op amp chips available. There are probably 3 that most guitarists would agree sound 'bad.' That makes at least 30 chips that either get a bad rap, or are dismissed altogether.

    I tested about 25 different chips back in '99, in a few 9's, a few 5's, and a clone. All had the socket installed, and were cooked (2 output resistor mod). One of the 9's was beefed up with better (i.e. more expensive) caps. The clone had premium caps as well. All of the '4558 variants sounded quite similar (and 'good').

    What was surprising was that the other 20+ chips all sounded at least fair, i.e. definitely not bad, and some sounded as good, or even better than the '4558-type.

    These 3, in particular, sounded really, really good.

    1. LM833
    2. OP275
    3. TL072 (my fave)

    The LT1214 was also kinda cool sounding, but not consistently so in the handful of pedals that I tried it in.

    I liked the 3 listed above enough to 'splurge' and order about 15 of each. They were consistently good.

    I then went on to check the specs of each 'good' chip. They had nothing in common. Even the slew rates, which some believe gives a hint to what makes the '4558 good, were all different.

    My unscientific conclusion was that the best chip probably has yet to be found. I may even run some new tests with more chips, to see if I can find something better than my beloved TL072.

    I don't think we'll see a pedal guru doing any sort of semi-scientific chip preference test any time soon though...

    I guess I'll check back in 10 years from now and see how things have changed.:rolleyes:

  15. scooteraz

    scooteraz Tele-Afflicted

    Apr 17, 2007
    Peoria, AZ
    Thanks for the chance to bounce ideas off of each other, I for one really enjoyed it.

    Ya know, we are using these chips sort of like we use tubes, completely outside the design parameters. Both devices were designed for clean signals, and of course, we all want some level of dirt. Maybe when we get someone to design a distortion chip....:lol:

  16. Robbie W

    Robbie W Tele-Holic

    Mar 16, 2003
    Lubbock, TX
    my 2 cents

    Personally, I think the TL072 sounds best in the Tube Screamer circuit, but this is my personal opinion for what I prefer as a player. The differences between the TL072 and the 4558 are subtle, but there none the less. The TL072 has a lot higher input impedance (extremely higher actually). I feel this is the primary reason for the audible differences. There are other factors like the slew rate that may contribute as well, but to me the input impedance difference is the biggie. The TL072 drives things harder and it is tighter and crisper.

    The 4558 in a Tube Screamer does have a sound that is good and is what a lot of people find to their liking. If you want "vintage Tube Screamer" then this is the best choice probably. Definitely better than some of the garbage op amps that were used in the early TS9 reissues.

    I have a ton of JRC4558's laying around, but I use TL072's and TL071's in just about everything I build that uses an opamp (TL071 being a single channel version of the TL072).

    Some circuits sound better with inferior spec'ed chips. The MXR Dist+ for instance needs the LM741 to get a decent sound. Put a TL071 in there and be prepared for an overly bright and brittle sound. The Rat2 is the same way. Remove the compensation cap and put a TL071 in there with the rest of the circuit unmodded and it sounds awful. The LM308 sounds great in there and it is a horrible opamp by todays standards.

    As far as 4558's in general I will say this. There is nothing magical about the "new old stock" JRC4558 that constitutes spending too much money for a "vintage chip". I will go as far to say ALL 4558's sound so similar I doubt anyone could hear a difference in a blindfold test. Brand new JRC4558, NOS JRC4558, TI RC4558....and any other brand 4558 will sound the same. Sorry to kick over any sacred cows but this is just my opinion based on my experience. If you hear a difference then by all means go with what sounds best to you.

    That being said....IMHO, YMMV,

    take care,
    Robbie Wallace
    RGW Electronics
    Last edited: May 25, 2007

  17. frankz00

    frankz00 TDPRI Member

    Jun 3, 2007
    Southport, CT
    Personally, I think it's the build of the pedal and the sum of all components. I have an hand-built DeMarco clone that I paid $119 for and it was worth every penny. I have another clone of the same circuit that I paid significantly less for and it shows. Both have the JRC4558. So I don't buy the Holy Grail theory. I attribute the superior tone to the builder of the box.

  18. Ben Harmless

    Ben Harmless Friend of Leo's

    Mar 10, 2003
    Allston, Mass
    Eh? That's one o' them boxes what makes yer amp sound real loud innit?


  19. kubton

    kubton TDPRI Member

    This is so true. Anything guitar audio is the opposite of all other audio. I feel a lot of this Holy Grail business is because we use things for unintended purposes. Opamps are design reproduce audio only louder in a pleasing(mostly transparent) way not distort in a pleasing way. So that adds much more subjectiviness. Boutique, money is no object, pedals still use really cheap opamps. The "best" sounding opamp I have ever used is the OPA2132PA but it would suck in a ts or the like.

    Any great sound is boiled down to a some magical component when it is difficult to replicate this great sound. So, what ever is rarest widget becomes the magic. i can't imagine they ever would be a discernable difference among the same chip of a different maker or decade even. There is just as likely the same amount of difference between the chips out of the same batch. I understand the nostalgia for the old and old sometimes is better but it is just silly applied to a jelly bean chip. Even mods the really make a difference to pedals what sounds good is so subjective and dependent on the two massive variables plug in to both sides of the pedal the guitar and amp. The sound of the ts is much more about the version of the ciruit build quality and the interaction with the guitar an amp.

  20. analogmike

    analogmike Tele-Meister

    May 9, 2003
    Connecticut, USA
    Like the Fender Telecaster.


    I have tried every chip and I still like the 4558 in TSs but I use a different one in the King Of Tone.

    Thanks for the cool post!

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