The Jazz Guitar Chord Dictionary
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  1. #1

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    I replaced the 300K pots in my Gibson Howard Roberts Fusion III guitar to give it a little more bite. It was somewhat of a challenge, more difficult than the same procedure in a ES-335.

    The HRF has treble rolloff capacitors and I kept them when I replaced the pots.

    Gibson Howard Roberts Fusion III and ODS Style Amp-hr-fusion-iii-pot-replacement-jpg

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  3. #2

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    Here is an example of the amp plugged straight into an amp I built about 12 years ago that I recently 're-discovered' in my stash of amplifiers.


  4. #3

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    Gibson Howard Roberts Fusion III and ODS Style Amp-124-jpg

  5. #4

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    I had one of those as my primary/only guitar for 15 years. Great guitar .. a bit heavy, but always liked it on the neck pup, but I definately get why you'd want to do exactly what you just did.

    The bridge pup on the other hand always sounded like absolute shit to me. I have no idea why I didn't get around to changing that. Do you feel the same way and is it better now? (Hard to judge from your clip)

  6. #5

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    Maybe I'm mistaken, but I had thought the 490-T and 490-R to be the same pickup with different string spacing. Either way, after the pot change I'm happy with the pickups and wouldn't change.

    I have had the HRF since the mid 1990s. It's sound was 'just OK' before, so I'd play it a little the put it away again. On a whim last week I got the guitar out and plugged it into the ODS amp, without even adjusting any settings and it was "Wow!" That is why I made the recording.

  7. #6

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    The amplifier I built is based on some amplifier design principles popularized by a Mr Howard Dumble.
    Gibson Howard Roberts Fusion III and ODS Style Amp-dscf3838-jpg

    Gibson Howard Roberts Fusion III and ODS Style Amp-ods_124044-rear-panel-f-886-jpg

  8. #7

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    Quote Originally Posted by icr
    The amplifier I built is based on some amplifier design principles popularized by a Mr Howard Dumble.
    The Big Rig, 4x 6L6. Your neighbors must appreciate that!

    A few questions if you don't mind:
    Did you scratch-build or was it from a 'kit'?
    Those two gut-shot pics, the top one's yours and the bottom one is Dumble?
    What Dumble # were you working off of? Does the bottom pic say #0129 on the filter-cap board?
    What amps do you play that left this one languishing in the corner?

  9. #8

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    Quote Originally Posted by icr
    Maybe I'm mistaken, but I had thought the 490-T and 490-R to be the same pickup with different string spacing.
    Pickup discussions are all subjective or functional .. I liked that slightly subdued dark sound in a neck pickup .. absolutely hated those qualities in the bridge. Doesn't do any of the stuff I want a bridge pickup to do.

    But cool .... If I thought of that maybe I wouldn't have sold my HR Fusion a couple of years ago

  10. #9

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    Quote Originally Posted by Sam Sherry
    The Big Rig, 4x 6L6. Your neighbors must appreciate that!

    A few questions if you don't mind:
    Did you scratch-build or was it from a 'kit'?
    Those two gut-shot pics, the top one's yours and the bottom one is Dumble?
    What Dumble # were you working off of? Does the bottom pic say #0129 on the filter-cap board?
    What amps do you play that left this one languishing in the corner?
    About 12 years ago there was a flurry of internet activity around Dumble amps. I got the chassis overseas and built the rest of it from the pictures of #124 that were floating around the internet at the time.

    Different people see different things when they look at pictures, so there are a number of schematics of #124 on the internet. This is the one I came up with and my amp is based on that. May or may not be the same as the original, but sounds pretty good to my ear.

    Gibson Howard Roberts Fusion III and ODS Style Amp-screen-shot-2020-12-30-4-23-45-pm-jpg

  11. #10

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    Years later I built the antithesis of the first one. This one is EL34 with a Marshall tone stack, it is a real hot rodded Marshal (HRM).
    I started this layout while awaiting parts, but just built the amp and never finished the layout drawing.
    Just like the original, it is built with Radio Shack parts...no kidding!

    Gibson Howard Roberts Fusion III and ODS Style Amp-layout-copy-jpg
    Gibson Howard Roberts Fusion III and ODS Style Amp-wiring-hrm-main-board-jpg
    Gibson Howard Roberts Fusion III and ODS Style Amp-hrm-inside-jpg

  12. #11
    300k pots? I never knew that! I've had my HRF III since 2008 and never gotten around to changing the pots, even though I probably should. I never cared for the 490s, and have replaced them with more smoth sounding ones. For straight up jazz, it's my favourite guitar, like a much fatter 335. I would probably go with another amp for that sound, but together with my Ceriatone OTS it produces a superb blues tone. Great combo, that's for sure!

  13. #12

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    Personally I think the only thing wrong with Norlin era Gibsons (and many post Norlin Gibsons) is the 300k pots. Otherwise, the pickups and construction are all worthy.

  14. #13

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    I changed the wiring to a ES-335 system built by Emerson Custom with Bumble Bee caps. (I did relocate the switch) The bridge pickup is a Seymour Duncan Handwound Candybucker. It is a '57 remake. And a Kent Armstrong 12 pole handwound PAF 5. What a change!. This is what I think the intention of Gibson was in the creation of this HR3. Jazz and Rock in the same guitar. It is such a nice upgrade this is the best sounding guitar. I have a 17" jazz box and it is close just not as much bass and not as much feedback. and switch to a rock amp and the bridge pickup is as good as any Les Paul or 335.Gibson Howard Roberts Fusion III and ODS Style Amp-20220513_150851-jpgGibson Howard Roberts Fusion III and ODS Style Amp-20220628_210005-jpg
    Last edited by Kevmc; 06-29-2022 at 12:05 AM.

  15. #14

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    Can you describe the sound of that Armstrong compared to a typical PAF style pickup? From the 5 I assume it uses Alnico 5 magnet?

    Asking for a friend who is a pickup geek....

  16. #15

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    I also assume the 5 means the magnet. The Kent Armstrong PAF 5 is smooth and has less background noise (scratches, pick scrapes etc.) I think it is potted. when it is on my jazz amp it is worm and smooth. It has a much fuller and articulate sound then the 490t. I think the wiring helped improve the sound also. It is hard to say what the pickup changed and what the wiring changed. I'm happy with the changes. This is my first guitar with treble bleed. I like it more without the treble bleed and the new pickups.

  17. #16

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    Quote Originally Posted by Kevmc
    I also assume the 5 means the magnet. The Kent Armstrong PAF 5 is smooth and has less background noise (scratches, pick scrapes etc.) I think it is potted. when it is on my jazz amp it is worm and smooth. It has a much fuller and articulate sound then the 490t. I think the wiring helped improve the sound also. It is hard to say what the pickup changed and what the wiring changed. I'm happy with the changes. This is my first guitar with treble bleed. I like it more without the treble bleed and the new pickups.