Ibanez Tube Screamer with one or two JRC4558D ICs, what's the difference?

[Ashura]

I am designing (redesigning) the Ibanez Tube Screamer distortion pedal circuit based on generalguitargadgets information (http://www.generalguitargadgets.com/effects-projects/distortion/tube-screamer/). I want to make the circuit smaller and learn about the process.

I have a doubt about this Ibanez Tube Screamer project:
Searching in Internet, I see that there are many versions of distortion apparently based on the original Ibanez Tube Screamer which, by the research, dates from the end of 1979.

The Tube Screamer suggested by the generalguitargadgets is a version containing a JRC4558D CI and is supposedly based on the first Ibanez Tube Screamer. It happens that in my searches I do not find photos and circuits of an original Ibanez Tube Screamer of 1979 that has only one operational amplifier CI, but with two ICs.

My doubt is:
Why are there projects of the Ibanez Tube Screamer (and its variants like the Tube Screamer TS-9) with only one CI operational amplifier while other Tube Screamer variants (including the 1979 original) have two ICs? What's the difference in using one or two CIs?

I thank everyone who can contribute with some information.

[idy]

All the versions we have seen (and that have filled hundreds or thousands of posts on this forum and other similar forums) have one IC with two opamps inside it. It is called a "dual opamp." That is like the 4558 or the many chips we substitute. The one you have also has two opamps on one IC, no? What do you mean?

[Mark Hammer]

Like many, I have never seen a version of the Tube Screamer that used two chips.  I checked my files to see if a Maxon pedal that may have been an early version of the TS-808, but everything used a single chip: a dual op-amp.

And that may be the source of your confusion.  Yes, the JRC4558 is one physical chip, but it includes TWO op-amp sections.  So photos of the board will only show one little black square, but schematics will show two triangles, each representing half of that chip.

Does that make it all less confusing?  Or is there some "secret" issue of the TS we haven't yet stumbled on?  Stranger things have happened.

[ElectricDruid]

All the versions we have seen (and that have filled hundreds or thousands of posts on this forum and other similar forums) have one IC with two opamps inside it. It is called a "dual opamp." That is like the 4558 or the many chips we substitute. The one you have also has two opamps on one IC, no? What do you mean?

+1 this. Not two ICs, two op-amps. In one chip. Hence the difference between the schematic (2 op-amps) and the pictures (1 IC).

Show me a photo of a tubescreamer with two chips and I'll believe you.

T.

[J0K3RX]

Some have 2 dual opamp IC's... One of the dual opamps is just being used for the input and output buffers instead of the transistors..

[StephenGiles]

I built a tube screamer for a neighbour's son years ago, a young lad who thought he and his geeky friends knew everything. He even gave me the circuit. For a laugh I built in a "bounce circuit" from the Eventide Instant Phaser - although not actually connected, to see if he noticed. Sure enough he asked me what the extra ICs (2 duals I think) were for, I told him that it was to comply with EU regulations!!!!!!

[J0K3RX]

Certain versions of the Maxon OD-808 had 2 dual opamps but, like I mentiond previously one of them was just being used as a buffer.
http://www.matsumin.net/diy/bunkai/od-808/OD-808_sch.BMP
If you are going for a smaller circuit you can ditch the buffers completely and just use 1 dual opamp. Many people prefer to leave the buffers off, nothing new there...
Pretty much all you could ever want/need to know about tube screamers at the link below.
http://www.analogman.com/tshist.htm

[ElectricDruid]

Some have 2 dual opamp IC's... One of the dual opamps is just being used for the input and output buffers instead of the transistors..

Fair enough, I stand corrected. I've never seen one.

In that case, to answer the OPs original question, "what's the difference between the one and two chip variants?" the answer would be "nothing really", since the buffers shouldn't affect the tone.

[StephenGiles]

Ah but it might affect the tone, and playing speed, if I may be so bold!

[ElectricDruid]

Go on then, tell me why...

[Mark Hammer]

Certain versions of the Maxon OD-808 had 2 dual opamps but, like I mentioned previously one of them was just being used as a buffer.
http://www.matsumin.net/diy/bunkai/od-808/OD-808_sch.BMP
If you are going for a smaller circuit you can ditch the buffers completely and just use 1 dual opamp. Many people prefer to leave the buffers off, nothing new there...
Pretty much all you could ever want/need to know about tube screamers at the link below.
http://www.analogman.com/tshist.htm

The earliest versions of the Boss OD-1 also used op-amps for the input and output buffers.  But  instead of a pair of dual op-amps, like the Matsumin drawing shows, they used an MC3403 quad op-amp.  I made myself a clone, because I had a couple of 3403 chips, and rather like it.

And once I had some clues for what to look for, I realized I did have an older Maxon schematic, as J0K3RX showed.

Is there any audible difference?  Given that they are used in unity-gain mode, I can't see there being any audible difference that might exceed the difference created by using one transistor type versus another (e.g., 2SC945 vs 2SC1815 or 2N4401), when transistors are used as the buffer stages.

WHY did Ibanez change from a pair of op-amps to a single chip and couple of transistors?  My guess is that it probably had to do with the flexibility it provided with respect to layout.  If the two buffers are in the same chip, the rest of the buffer circuit MUST be situated near-enough to the same chip.  I don't know this for sure, just guessing.

[StephenGiles]

I think that's probably the answer Mark.

[Ashura]

Thank you to all who have participated so far in this discussion.
In my searches, before posting this question that we discussed here, I found this site http://www.analogman.com/tshist.htm (the same as you indicated, J0K3RX). In it we can see a list that, according to the site, would be of the models of existing pedals that would be based on the original Tube Screamer TS-808. At least that's what I understood.
We can see the list starting with a model identified as "104322? (R) JRC4558D 1980, 80 / 15th week caps, nut on power jack". I do not know if this order in the list indicates the manufacturing order, but even if it is, I did not find clear circuit information or photos of this particular model. Maybe it's something that has gone unnoticed in my research, or I have not researched the right place.If anyone knows something and can say here about this model, I will be grateful.

Still seeing this list of models I could not identify one that was from the year 1979. This was important for me, since, in principle I imagined that my construction should be based on the first pedal (I was thinking that it should be the closest possible that I can do of the first ... being, if possible, smaller); but I still do not know if that would be the case now. Maybe I'll end up with one that is not exactly like the first, since as I continue with the search, I now see that the successor, TS-9, seems to have a building that produces a better sound (if someone can disagree this, or confirming this, is welcome to manifest itself ) and the reproduced sound is more important, for my purpose, than being exactly like the original.

To try to clarify a bit more how I got the doubt that generated this post, follow these photos:
Here we see a PCB with two ICs:

In this link, where the author say to be photos of an original, it is possible to see (http://www.jacquesstompboxes.com/ts808.html) that has only one IC.

And in this image one sees a supposed comparison between the models Narrow box TS-808 (which to date, according to my research, is the first original Ibanez Tube Screamer pedal of 1979) and the TS-808 reissue of the 35th anniversary. We see two ICs.


Here we see a schematic apparently of the original pedal posted here in the forum at this address: https://www.diystompboxes.com/smfforum/index.php?topic=116462. msg1082250#msg1082250


Here is a schematic for anyone who wants to mount a true bypass version, in this address: https://www.electrosmash.com/tube-screamer-analysis


Here we see the schematic of generalguitargadgets http://www.generalguitargadgets.com/pdf/ggg_its8_sc.pdf

We see that in the schematics two ICs appear and in the mounted pedal photos two ICs or an IC can appear. Being that when two ICs appear, the photo seems to be of the first versions (or first ...?) of the pedal. And the IC of the first version, by what I understand when viewing information on the manufacturer's website (http://www.ti.com/product/MC1458/samplebuy?CMP=conv-poasamples) seems to be a dual operating amplifier (http://www.ti.com/lit/ds/symlink/mc1458.pdf).

[thermionix]

The "narrow box" version was sold only in limited markets, I think in relatively small numbers, and not often thought of as being in the Tube Screamer family, even if it was called that.  The main versions, TS-808 and TS-9, have almost the exact same circuit, just two resistors are different.  Which of those two sounds best is obviously a matter of opinion.  I like both quite a bit.

[reddesert]

From Analogman's website at http://www.analogman.com/tshist.htm:
"There were some TS-808s made in the 1979 period, mostly for other than USA markets, that came in a narrower box. These have a bottom plate that unscrews to change the battery like an MXR pedal, no plastic battery cover. This narrow TS-808 had a different circuit. It uses two 1458 chips which are the 1st version of the low-tech dual op-amp."

Also from Analogman: "These had a circuit board labeled OD-801. This board can also be found in some old Maxon OD-808 OVERDRIVE pedals ..."

There's not a conspiracy here. Maxon was the company that actually made the pedals for Ibanez. They sold a version of the design, called the Maxon OD-808, that used a second dual op-amp for the I/O buffers instead of transistors, as noted above. That version appears to have made it into these early narrow box TS's.

It shouldn't make much of a difference to the sound what is used for the buffers. Since Tube Screamers are subject to an inordinate amount of debate over small differences, perhaps you should make one with transistor buffers and one with opamps. (And then make a Zendrive, which omits the buffers entirely.)

[StephenGiles]

Or even one with both!!

[thermionix]

In this pic it looks like Analogman has replaced the impossible-to-find Panasonic MA150 clipping diodes with somewhat difficult-to-find Toshiba 1S1588s.  Silly.  Both types were commonly used in original TS808s and TS9s, but I think Maxon neckbearded all remaining stocks of the MA150s to include in their reissue OD808s.

[Mark Hammer]

"Neckbearded"?   

[Andrekp]

As that two IC schematic shows no NEED for two double op-amp IC's, I would suggest that maybe there were physical reasons for using two 4558's when one would do.  Maybe the PCB was just easier to lay out.  Maybe it avoided some parasitic problem.  Maybe, maybe, maybe.

Though unusual, it would not be the first time a variation exists where some versions use discrete op-amps, and some use multiple on one chip op-amps.  (aren't there Phase 90 variations like this?)

[Mark Hammer]

The header of this thread asks "What's the difference?".  I'm presuming the implied question is whether there is a sonic difference.

A couple years ago - maybe 3 - a local buddy brought over his Timmy pedal, because he had read somewhere that use of a 1458 dual op-amp "improved" it.  I was skeptical, but installed a socket, and we tried out about a half dozen other dual op-amp chips.  And sonuvagun if we didn't both prefer the 1458.  The basis for this would seem to be the more limited gain-bandwidth product the 1458 has, compared to the 4558 or 4560/4580.  It just sounded less harsh when gain was dimed.

What could a person infer from this?  Well, I suspect the use of op-amps for the buffers plays little to no role.  Gain/bandwidth would play no role at unity gain.  However, use of a 1458 for the higher-gain clipping section might - and I emphasize might - provide a slightly warmer color to the sound at highest gain settings, where limits on the chip's ability to produce lots of gain for higher frequencies comes into play.

HOWEVER, this is all conjecture, based on subjective experience (rather than objectively measured) with a related, but still different, circuit.  Is the result going to be all that much different than a "normal" TS circuit with a bit of treble-taming after it?  Maybe, maybe not.  Is it the sort of putative difference that would only show up when fed with an input that already has high end, like single coils?  Maybe, maybe not.  Throw in component tolerances for those caps that set upper and lower bandwidth points in the circuit, not to mention Vf differences between diodes, and it might be an impact that comes and goes, from pedal to pedal, like a ghost.