Ibanez Js100, Early 90s, Mods - Help Required

Discussion in 'Guitars' started by Shreddy Krueger, Feb 18, 2019.

  1. Shreddy Krueger

    Shreddy Krueger Active Member

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    A curious situation I'm finding myself in at the minute. I've been playing Suhr guitars for quite a few years now, recently I've played around with (though not owned) a couple of the new custom shop SGs and LPs, which were fantastic, however, an old acquaintance came back into my possession the other week, and I'm divided over which way to go with it.

    I owned this guitar for a brief spell in the late 90s. It's always been in the family since new. It has had the pickups upgraded to Fred/PAF Pros, bridge and trem upgraded, brass block, high pass filter on a refitted volume pot, fret work, etc. I like the feel, the neck works for me, but the guitar, surprisingly, comes across as being very dull and 'vintage', which really took me by surprise. In fact, I'd say that it compares to an SG in that respect. It's quite dark sounding, and the volume rolls off in a way which sucks the body out of the sound -- no nice Hendrix-esque tones here when you roll off, just a flubby muddy dilution of the sound.

    I did wonder if the replacement pot and wiring had been fudged -- something outside of my realms of experience (I just play 'em) -- but after taking the back panel off the pot is unmarked, so that doesn't really help. The tone pot is 500k. My first instinct was that the volume pot was 250k.

    Any thoughts, musings, ideas -- feel free! :yesway:
     
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  2. stringtree

    stringtree Well-Known Member

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    Any pics of the control cavity...

    I've owned the JS 100, fantastic guitar. Had the frets done to 6105 and his name removed from the 21st fret. I had the tone zone pickup in the bridge and it sounded just fine. Great playing and sounding guitar.

    Couldn't say what actually is causing it to sound the way it does for you...
    I'm sure there are those here that know such matters..:dude:
     
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  3. Shreddy Krueger

    Shreddy Krueger Active Member

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    Thanks, man -- yeah, I took a couple of pics but I don't have anywhere to upload them (I don't have social media, instagram, etc). Funnily enough, I was thinking about the Tone Zone/Air Norton pairing myself recently.
     
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  4. Wildeman

    Wildeman Well-Known Member

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    Look up treble bleed, it keeps your tone the same when you turn you volume down. Can be done for a couple bucks, way cheaper than new pickups.
     
  5. Shreddy Krueger

    Shreddy Krueger Active Member

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    Thanks for this ^ I already had a treble mod installed to the volume pot, turns it into a push/pull that lets a lot more signal through, but it doesn't really cut it for me. I'm starting to think that there's something wrong with either the pot that was installed (i.e. 250k instead of 500k), or the capacitor, etc.
     
  6. BowerR64

    BowerR64 Well-Known Member

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    Yeah the high pass filter you may want to try it without that

    Ive never tried that combo of pickups but here is what the DiMarzio page says

    "FRED® started out as a prototype designed to add a little midrange to the PAF Pro®. When we sent one of the first ones to Joe Satriani, he discovered and exploited a unique tonal characteristic — the ability of the FRED® to emphasize upper midrange and treble harmonics through an overdriven and distorted amp. Many standard humbuckers have a tendency to fatten up with distortion. The FRED® does the opposite; it gets tighter and brighter, much like a single-coil. Joe uses the FRED® strictly as a bridge pickup, but it's also a distinctive neck pickup — it works really well with any humbucker of equal or higher output."

    The tone chart of that pickup says Bass= 5.0, mid, 6.0, treble, 5.5

    So i dont understand why you would put a pickup in that has a treble hump then add a high pass filter?

    Fender put 250K pots in the strat because the single coils were so bright the 250k took that shrill off the top.

    I was going to suggest flipping the neck and bridge pickups around but they are about the same pickup the Fred just seems to have a tad more output.

    Put a set of Suhr pickups in it. Which ever set you like in one of those.

    Also im curious, you said you upgraded to a brass nut? Then you said Bridge and trem upgraded? Doesnt the JS100 have the Edge LowPro in it? or is this not the good one? I see so many different used prices for the JS100 from $400-2.5K
     
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  7. Shreddy Krueger

    Shreddy Krueger Active Member

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    Thanks for this ^
    The high pass filter (which is kind of like a bright cap) is on all of the premium JS models. It's there to make that volume roll off less muddy, but it isn't working how I would want it to work in this instance (too much signal passes through, hardly any roll off at all). I went with the Fred and the PAF Pro as they're pretty much a perfect fit for this guitar (theoretically, at least).

    I upgraded the block to a brass one -- for resonance.
    This is an original run JS100, made in the early 90s. They've changed the spec since then and I think they're currently on the Edge 3 (or were the last time they did a run of 100s).
     
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  8. stringtree

    stringtree Well-Known Member

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    Humbuckers usually have the 500k pot and single coil the 250k pot. Also should be audio pots as opposed to linear for volume control. This is a basic starting point, not set in stone type thing. Its what your after that counts.

    I found this info over the net, from another forum:

    Choosing audio (log) vs. linear depends on what you will be using the pot for. You should always use audio pots for volume control, otherwise you will find that the volume does not change smoothly as you turn the pot up and down. With a linear taper pot, you will find that the volume increases slowly from 0 to about 60 or 70 percent, then increases rapidly from that point on. This is because there isn't a direct relationship between resistance and volume in a passive circuit (which is what a guitar with passive pickups is). Audio taper pots compensate for this, and give you a consistent volume change throughout the sweep.

    A tone control, on the other hand, works best with a linear taper pot. The role of a tone control is to feed part of your signal to a capacitor that bleeds the treble to ground. In order to have a smooth transition from bright tone to mellow tone, the pot has to be linear. You can use an audio taper pot in a tone control, but you won't find the tone roll-off to be as smooth as it could be.

    Regarding capacitors: a guitar's tone circuit is what is known as a passive low pass filter. The capacitor only lets high frequencies through, and it dumps these frequencies to ground. Whatever is left (low frequencies) continues on to the volume control and out the jack to the amp. This is why it's called a low pass, because the lows "pass" through the circuit while the highs are blocked.

    As Jeremy said, the value of the cap determines at what point in the frequency spectrum the frequency cut-off occurs. The higher the cap value, the lower the cut-off point will be. In other words, higher value caps will make your tone darker when the tone control is set below 10. Strats and Teles generally have .022 uF caps and Les Pauls generally have .047 uF caps. I have seen guitars with caps as high as .068 and as low as .010.
     
  9. BowerR64

    BowerR64 Well-Known Member

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    WAit, maybe i read it wrong then. I thought a "high pass filter" was to filter out the lows so depending on what frequency you select it filters out the lows and lets the highs pass threw so that in a band situation you and the bass player dont walk over each other?

    Is this what the "bright cap" in an amp does? I thought it adds some clarity or brightness when playing at lower volumes.

    I dono ive never tried a high pass filter in a guitar so just ignore my post. Im new to the bright cap, high pass filter thing its just kinda what i thought about it.
     
  10. stringtree

    stringtree Well-Known Member

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    From what I've read, the high pass filter is used for the purpose of retaining the highs when rolling the volume down on the guitar.

    Shreddy Kruegger is experiencing the opposite effect.

    This might shed some light...
    http://www.tdpri.com/threads/high-pass-filter.849114/
     
    Last edited: Feb 20, 2019
    Mitchell Pearrow likes this.

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