JRC4558 myths...

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

  1. electricbody

    electricbody Tele-Afflicted

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    I'm happy with my TS7. I guess I should have said "a pedal" and not "the pedal" as I wasn't referring specifically to the TS7, but I can see how the sound a pedal makes isn't exclusively the result of the main chip.
     
  2. Airguitar

    Airguitar Tele-Meister

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    I dig my TS7. I tread lightly on it and it hasn't let me down in 4 years.
    It sounds good and I'd definitely replace it if it were broken or lost. Thinking of adding a Bad monkey to the chain too..

    The tone has so much to do with so many factors, the greatest of which is your hands, then component tolerances in ALL the pedals in your board, your cables, impedances between pedals, the list is endless..
     
  3. macpgh

    macpgh NEW MEMBER!

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    I stumbled upon the thread here today while researching.....
    Although its a few years old, you guys are missing some key points.
    First is that you have to consider the bench mark....an original pedal along with original components inserted into the board.....
    BUT what you are missing is the point of the board itself. You've hit around but not bullseyed the situation. What's key to an original bench mark and reissues and the clones etc.....is the layout of the board and its traces and the thickness of the traces and spacing of the traces.

    Sort of mentioning lead dress kind of comes close....but misses. There is some radiational aspects of passing signal whether it be thru traces or thru wires if you consider point to point wiring.
    But this all goes hand in hand with the component selection and any variances. If you were blueprinting and measured each component to narrow the variance....then you could get a more consistent scenario to measure the chips.
    As it would be out of your control to measure and blue print the chips

    As far as production line aspects of an original pedal. There was an engineering staff set to project out the pedal....they applied the paper and mathematics of formulas and data sheet specs for a chip to complete their assignment for production. They proto typed a unit or 2 for demo purposes to make sure it worked and was reliable and was assembly line proof for production......then it went to the factory floor for production.
    Being a player......what is not in this is......what might be good on paper might translate spot on.....but usually it comes down to the fine tuning. Minor variances might need to be tweaked in a final tuning since all points are not equal due to production variances and tolerances.


    And as points made regarding the diodes.....that's spot on as the relationship to the clipping thresholds is critical.....and that's usually due to the material of the diode.....whether it be silicon or germanium or some other type diode.

    Speaking from a vacuum tube perspective in signal processing and amplification......
    The capacitors can be critical in determining sonic characteristics. The material of which they are made is generally the secret of the sweetness of the sonic character.....but then that's also a part of the ear candy aspect too.....per individual.
    In circuitry I deal with, polyester film is what I favor and certain types have that midranged junk in there that makes for that sweet sound of a tube amp. The polyprop material caps tend to be a lot more smoother in response. From my perspective, the ceramic caps are not the caps of choice if I were building something as they tend to sound on the harsh side.....
    But if you open up a lot of vintage amps other than the fender's, the cheaper lesser amps of the period that are now considered the vintage sound....., what you usually find in them is the cheaper ceramic caps.....
    Those cheap junk ceramic caps along with undersized transformers that are not performance oriented and low plate voltages on tubes......that's what makes for that coveted sound response.
    If it were to be translated into an IC chip solid state based item......then the ceramic caps would be the way to go if you could blue print the whole package for consistency......again the variable is the variance of the IC chip.

    And last but not least......
    For those of you that are more clinical.....break out the scope and measure a known specimen that is sonically sweet. If you were to blue print.....the magic is in the pedal itself as opposed to the schematic. The variances within that pedal determine the deviation from the schematic values that make it what it is.....as far as ear candy.
    If the typical variance of components is 10% up or down......in something dealing with low voltage.....whoop there it is

    And as far as using carbon composition resistors......its the hiss...the noise inherent.
    Personally I would not use them. And the carbon films kind of are much more clean sounding but a notch "noisier" than the typical metal film. But point being here is that they are seeing very low voltage.
    With respect to a high voltage vacuum tube amplifier, there are certain points in the signal chain where such carbon composition resistors ramp up to critical limits where such stress causes the magic......voltage stress from high voltage.
    You aren't getting that from a 9 volt in a solid state circuit.......
    The circuit is trying to replicate that via clipping an IC amp.....and it comes down to symmetrical or asymmetrical clipping.
    Typically tube amps are asymmetrical but that's probably due to more of production tolerances and component variances.......production line mass production......and no fine tuning.
    If it were HIFI, then there would be much more tweaking for symmetry .
    In theory on paper it should be symmetrical sign waves......but in practical....its asymmetrical.
     
  4. Anode100

    Anode100 Friend of Leo's

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    Imprecise components amplifying an impure signal - all the graphs in the world won't do you any good.
     
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  5. Rockledge

    Rockledge TDPRI Member

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    I don't think the chip differences is mythological, but I do think there are differences that are noticeable, but that those differences are subject to personal taste.
    I have an newer TS with the 4558 chip and I don't like it nearly as well as the older one I have with the TA75558 chip. The one with the TA chip has a more present tone, less compressed sounding and less muffled, as if is passing the guitars natural sound better without coloring it.
    I use a TS to boost the input to the amp, I keep the dirt cranked on 0 and the level all the
    way up. On a few songs I crank the dirt. I run it into the clean channel of a low wattage tube amp in order to drive the tubes hard, which works well.
    It only makes sense that identical 4558 chips made at different factories at different times could sound different, it is hard to imagine that they all get their raw materials from exactly the same source over the years. But I also think other component from various factories over time could make enough of a difference that the chip differences are not the only factor.
    I do understand why the 4558 chips are preferred, they do indeed have a warmer tone, or at least in my experience. Warmer as in a little more compressed with the highs less exaggerated.
    As in the highs that affect the lower frequencies, the overtones.
    The TA chip seems to me also to have more overtone affect on the lower frequencies than the 4558. For example, I bet a guys that like telecasters for the low string chime that includes high overtones would probably not care for what a 4558 chip TS does to their tone, but might tolerate the sound my TA chip one has.

    way up.
     
  6. Deebs3

    Deebs3 Tele-Meister

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    Lots of other pedals also had the JRC4558, my old boss phaser has 4, i think the CE2 had one as well.
     
  7. artdecade

    artdecade Poster Extraordinaire

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    2007 thread bump? Stop that.
     
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  8. NWinther

    NWinther Tele-Afflicted

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    So much said for such a small thing... It really matters alot...... ;)
     
    Last edited: May 9, 2019
  9. DougM

    DougM Friend of Leo's

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    I'll let Brian give his opinion.
     
  10. uriah1

    uriah1 Telefied Ad Free Member

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  11. uriah1

    uriah1 Telefied Ad Free Member

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    cool Mike. I am not worthy...Still have 2 pedals you modded for me..still great.:)
     
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  12. leonard d rock

    leonard d rock Tele-Afflicted

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    i never had actually done any strict AB comparison of TS pedals until recently when i had the time and i compared the ts808 and ts5 with a nux od3 and visual sound rt 808 (bass switch off) and at same knob settings they sounded almost the same. even the sd1 sounded the same with just a little tweak of the tone to make it less sharp. i have on order a caline midlander and a joyo vintage od and i will add those to the comparison as well
     
  13. Rockledge

    Rockledge TDPRI Member

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    I just couldn't help myself.
     
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  14. Rockledge

    Rockledge TDPRI Member

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    I just couldn't help myself.
     
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