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The "true" TS-808 chip...
Aargh. It's all coming back - the frantic hype of New-Old-Stock Operational Amplifiers (or NOS chips, as they are sometimes referred to), for modifying a TS-9 Tube Screamer to TS-808 specs. In all fairness, I guess the subject never really went away - it just slipped under my horizon for a while.
As always, there are several issues lurking inside the one here, and I'll try my best to put my red mist aside and adress them in an orderly fashion. I'll start by dispelling a myth...
"The original TS-808 chip"
The JRC4558D is claimed to be "the original TS-808 chip" - not only by people peddling surplus NOS units on eBay, but moreso by regular people who have heard this, and perceive it to be true. Let's put this issue to rest once and for all: there is no single "original TS-808 chip", ok?
The TS-808 was shipped with at least three different op-amps during its lifespan - probably due to what was available at the time.The schematic simply calls for a 4558, which is a fairly standard dual operational amplifier, which can be had from several manufacturers. The Japan Radio Company was/is just one of many such manufacturers. As a result, many of the TS-808's were shipped with the TI RC4558P, a cheaper malaysian version produced by Texas Instruments. Other TS-808s used the JRC version, while others still had a TL4558P. I haven't heard the TL version myself, as there seems to be relatively few of these around, but the other two sounds quite similar. There are differences of course, but not enough to sell your mother for... And while it's the JRC chip that has gotten all the attention, it is worth keeping in mind that some of the awesome-sounding TS-808s have had the RC4558P chip inside.
To NOS or not to NOS?
I've stated this before, but for the sake of it, here goes... Let's start by making two assumptions:
- You hold in your hand two prime examples of the same op-amp. Same designation number, same manufacturer, same specs. One was manufactured some 20 years ago, while the other just came off the line.
- These two op-amps were manufactured using the same production line, and that their specs haven't been "improved" somewhere along the way.
As long as these two conditions are met, there will be no difference whatsoever between a new, unused op-amp that was manufactured in the '80s, and one manufactured yesterday. Integrated circuits don't change with age, like electrolytic capacitors do, they only change with use (and even that isn't a certainty). Now, since NOS - that most coveted of labels - simply means New (as in "never used") Old (as in "manufactured long ago") Stock (as in "has been sitting in a warehouse somewhere"), a NOS op-amp is just as new as a "new" one...
Hence, putting that NOS JRC4558D op-amp into your reissue TS-9 will not turn it into that awesome-sounding 1981 TS-808. It will get you closer to what that specific 808 might have sounded like 20 years ago, but unless you find an op-amp that has seen 20 years of use, you will not get there...
Unless you need to know that you have "the real thing" in your pedal, there's no need whatsoever to chase after that NOS op-amp. There's no need to pay top dollar ($15 or so isn't unusual for an '80s NOS JRC4558D, but I've seen them advertised for as much as $45) either, when the same part will cost you 50 cents at Small Bear. But... if only it was that easy. Remember the two main op-amps found in TS-808's? For some reason, only the JRC chip has been elevated to "NOS" status - there seems to be no real market for NOS RC4558P chips, even though some of the best-sounding TS-808's used them. Upon further investigation, we find that their production histories differ somewhat, which means that they might not meet the two conditions as outlined earlier.
TI RC4558P vs JRC4558D - what's the story?
As mentioned earlier, there were several different types of op-amp chips used in the TS-808 and TS-9 - all are of the general 4558 type, but from different manufacturers. This feature only focuses on the two main contenders - the 4558D from JRC and the Malaysian-made RC4558P from Texas Instruments. However, those weren't the only ones used.
As we can see, there were at least three different chips in use, in each of the pedals. In the case of the TS-808, the TL4558P is by far the rarest, with the other two being used rather randomly, as it would appear - they both appear all over the timeline. With the TS-9, the timeline is clearer. For some reason, the first TS-9's had a 2043 chip from JRC, instead of the others that worked so well before. After that, they switched to yet another previosly untried contender, this time from Toshiba (the TA75558), before switching to the JRC4558D. For the last production run, they switched once again, this time back to the TA75558 - which incidentally is the op-amp that is used exclusively in the reissue TS-9's.
With that established, we need to look at the two main contenders here, and what happened to their production lines. Pictures are of original ´80s items - current production looks slightly different.
Japan Radio Corporation JRC4558D - in the early '80s, JRC churned out millions of these chips, and they appear in virtually every piece of Japanese electronica from this period. The company later (mid-to-late '80s) changed their name to NJM, and moved their production facilities to East Asia. They continued to produce 4558 op-amps - aptly named NJM4558D - but since the factory was moved and new production equipment brought in, it can be argued that it wasn't the same. A few years later, NJM started re-issuing the JRC4558D, but not produced at the old plant, though. The specs are the same as the old one, but the suspiscion still lingers - since they changed facilities, are the reissue chips really as good as the old ones? If anything, the doubts has made room for a NOS market.
Texas Instruments RC4558P (Malaysian) - this one has a slightly different story, as it seems. From what I can gather, this chip has been in production in Malaysia ever since the time we're interested in (late '70s - early '80s), and to my knowledge the factory hasn't changed much since. As previously mentioned, there seems to be no market for NOS RC chips, and this may well be the cause.
So... what to do? If you ask Robert Keeley - whose opinions and taste I definitely trust - the reissue JRC4558D is only fit for the bin, whereas the NOS units are just fine. For most of his work, though, he uses the current-production RC4558P, as it is his favourite. Analog Man takes a different approach - he will happily install the RC chip if you ask for it, but his own preference is for the new JRC chip. Me? I usually use the current production JRC4558D, and am very happy with the results. Compared to the RC, I find it to sound slightly smoother and nicer, although I do use the RC4558P in pedals where the extra rawness seems needed.
So, is it in the chip? Or, what is it that makes the difference?
In some cases, simply replacing the op-amp chip will make a definite improvement in tone. For instance, the reissue TS-9 uses the same Toshiba op-amp as some of the later original TS-9s - the TA75558 - and though it is a lower-noise, higher-spec version of the 4558, it doesn't seem to suit this purpose very well. Replacing one of those with any of the usual 4558 op-amps will make a big difference, no doubt. But from there on out, once you get one of the "good" chips in, the differences gets increasingly marginal. Scott Henderson once said, upon having tested a RI TS-9 modded to 808 specs - using the reissue JRC4558D, to boot - that it sounded much better than his original TS-9 - despite the fact that his pedal had the original JRC chip... Apparently, once you get one of the proper op-amps in, it's the two resistors in the output section that make the big difference.
And do remember that the op-amp has very little to do with the actual clipping in a TS circuit. It's just there to amplify the signal - the diodes to the clipping. Changing one or both of the diodes will make a huge impact on the overdrive character, while the differences incurred by different op-amps are minute.
To complicate matters further, there are also other differences between the pedals that we haven't even begun to touch - for instance, the pots used in the TS-808 are vastly different from those in the TS-9. Their values are the same, but their looks and construction are different. Also, the capacitors used in the different series (TS-808, TS-9 and reissue TS-9) vary - and sometimes they vary within the same model/year as well, for the same reasons that the op-amps varied.
Conclusions
Several thoughts and hunches have surfaced during my writing this piece, and to some extent - and on certain issues - I have actually changed my position somewhat. Here are my findings:
- Basically, the RC4558P produced today seems to be exactly the same as the early '80s ones, whereas there seems to be some merit to the claim that the JRC4558D manufactured today isn't quite the same as the '80s units. The new JRC4558D seems to sound just fine, though, and I use it extensively.
- If your pedal is a reissue TS-9 or a TS-9DX, it will definitely benefit from an 808 mod. In fact, any TS-9 with the TA75558 chip will improve a lot. Slighter improvements will be had from TS-9's with the JRC2043DD chip - even though some claim it to be a "bad" chip, it's not that bad... And if yours has a JRC4558D chip, you will still notice an improvement if you change the resistors to 808 specs.
- When shopping for a suitable op-amp, consider the RC4558P from Texas Instruments - you will only pay half a dollar, and it's just as good as the ones that came in lots of the TS-808's. Also, don't hesitate to try the current production JRC4558D - I like it the best, and after all, it's good enough for Analog Man... I've also tried several of the outsiders - TL072, LM833 and others, and didn't like them. But you might, so don't rule them out because of me. The MC1458 is really nice, but possibly a bit noisy, and a more hi-fi option is the Burr-Brown OPA2134A. Choices... in the end, I usually end up with the JRC4558D, as I find it to produce the best overall sound. Oh, and if you're modding a Boss SD-1, I don't think it is neccesary to replace the JRC4558DD with a JRC4558D - the extra "D" simply signifies an extra layer of shielding. This makes the "double D" slightly less noisy and slightly less susceptible to outside interference (RFI/EMI etc), but it doesn't seem to change the sound one bit.
- If you decide to get a NOS item - make very sure that is what you're actually getting. '80s JRC chips has a four-digit date code in the lower right-hand corner, and they are shiny. Reissue chips have five digit codes, often with the fifth digit being a letter, and are matte-finished. And if you do find an original, don't pay more than $15 or so - there's no need to inflate the market further. For that price, you should get a complete kit with op-amp and socket, resistors and instructions. And again - look carefully at what you're getting. You won't have to search long on the Internet to find mod kits with reissue JRC chips, selling at $15 or above - remember, that's an item that costs 50¢ at Mouser...
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