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to fullcircle users, basic tech question

Discussion in 'Amps, Mics & Pickups [DB]' started by clochard, Mar 27, 2006.

  1. Greetings folks,
    i've just hooked my db to my new and proud swr-wm12 from my fishman fullcircle PUP, and something doesn't sound right. 2 technical things could cause what I hear (or don't hear), and i'd like your take on these.

    problem: sound seems full enough on lower notes (more or less the lower E and A), but sound kinda "incomplete", ie lacking body or warmth on the mid-upper register.

    a] Obviously, impedance mismatch may be a problem, but from what i've heard of its usual effect, i'm not convinced this would undubitably be the cause. Any inputs on that?

    b] I've had the PUP installed by a reliable luthier with a stronger bridge, but the bottom of the wheel seems awfully close to (if not totally resting on) the base of the bridge. I've read in the documentation that it may cause a "muting" effect. If that'd be the case, wouldn't it cause the lower-end notes to sound muted as well?

    From you fullcircle users, any reactions/inputs/taughts/questions/advices to help me in my quest for a "freeer" sound? Thanks in advance for sharing your experience and knowledge!

  2. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    Short answer, I'm guessing that you have the bass knob up to high.

    Because the pickup is on one side of the bridge, those strings are going to sound more pickup-y/piezo-y. This sound is naturally (or unnaturally) compressed, which may add to your effect. Balance the treble/mid/bass so that the notes are coming off into the room balanced and then adjust for tone.
  3. You could try rotating the pickup 90º (¼ turn) - according to FC instructions, this might change the sound you're getting…

    Other thoughts: you said that the bottom of the wheel is close to the base of the bridge - I wonder if it makes a difference as to which way up the Full Circle is installed… (pause to check…) …both my basses have the FC installed with the wheel touching the top of the bridge feet and the threaded part screwed into the bridge itself, so the gap (if any) would be between the pickup and the upper part of the bridge.

    - Wil
  4. hdiddy

    hdiddy Official Forum Flunkee Supporting Member

    Mar 16, 2004
    Richmond, CA
    I had a full circle on my bass too for a while. I think it definitely needs some support from a preamp, preferably a Fishman in particular. However I to noticed other it wasn't completely consistent either. I eventually took it off as the Revolution Solo was a better choice floor me. Try it tho with a preamp -I think you'll hear the difference.
  5. PB+J


    Mar 9, 2000
    arlington va
    I had a full circle for a while and liked it a lot--It went with the bass when i sold the bass.

    Sounds like an impedance mismatch to me, although as I remember the full circle was really friendly to ordinary amps. You could try putting a preamp in front of the SWR, or maybe build Fdecks little impedance matching preamp, which is cheap and easy to make. You can find it by searching this forum.

    Are you using a lot of eq? I never liked the "enhancer" knob on SWR gear, i could never figure out what it was doing except scooping mids
  6. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    Good advice so far. Try it with a few other amps. SWR is famous for the sound you're describing, expecially with the "enhance" knob engaged. I run mine on an AI Focus with the HP filter engaged, and that helps a ton.
  7. bassist14


    Oct 17, 2005
    i use a fullcircle with a gk mb 150e and a markbass top (500kohm input) without any impedance-problems. (without any preamp) on both amps the eq is nearly flat, and the sound is very even. i never had the problems you described. i would try it with another amp, i don´t think the fullcircle is the problem.
    hope this helps.
  8. thanks for all those fast-sprung replies [keep em comin!];

    indeed i'll have to try with other amps *and* with a preamp [things I do not own... i guess i'll get the networkin goin]. Still, upto now, fellow bassists had approved the general "regular-amp-friendly* behavior of the fc pup. I guess having the lower half of the sound-scope set up to "mostly excellent" is a good start. Which goes to confirm that the upper end is always where the trouble comes from :smug: .

    At the moment, playing with the eq knobs didn't attend the matter. I've been intrigued by the effect of the aural enhancer, which only modulated the smily aura I was bearing, without doing much good [or any bad, for that matter] to the db's sound. It mostly seemed to modulate it in an unsuspected way :).

    It's interesting to see that other basses were set up with the PUP not showing any gap to the bridge's foot.

    Keep your comments coming, and i'll try to update this thread with other eventual experiments that'll have to be done regarding this matter. This is all overwhelmingly interesting for me.

  9. PB+J


    Mar 9, 2000
    arlington va
    I always had a slight gap between the bridge and the wheel--very slight at some times of the year, like just enough to slip a sheet of paper in between. I should report I never actually used the full circle with an electric bass type amp. I used it with relatively high impedance inputs, like 1-10 meg ohm, with various preamps. I never noticed a difference between 1 and 10 meg, but maybe if i'd tried it with a different amp...
  10. mesmithnm


    Dec 10, 2005
    Layton, UT
    I've got FC's installed on two basses - a carved german factory bass and a '52 Kay M1B. I go straight into the passive input on my iAMP 600 (1 megOhm). On the german bass, the FC is mounted with the wheel in contact with the part of the bridge in contact with the strings (the top). On the Kay, the wheel is in contact with the bridge foot. This wasn't so much because I wanted to mount the pickups this way, it's just the way the bridges were drilled and tapped for the adjusters. The Kay has a short bridge and the bridge feet just aren't deep enough to accomodate the threaded part of the adjusters. I can't really do an A/B in sound because each bass will only accomodate the FC installed one way, but I'm getting good performance out of both. The FC is definitely the best pickup sound I've gotten out of my basses (used Realist, tried and gave up on Rev Solo, used Underwood for years when there just weren't that many options). But, on both basses the wheel is not in contact with both the bridge top and bridge foot simultaneously. Seems like you could check and see if the sound is getting "choked" because the wheel is simultaneously in contact with the top and bottom of the bridge by just cranking the adjuster up until you're sure there is daylight and listening for changes.

    Also, I checked the SWR web site - the WM-12 manual doesn't list a value for the input impedance of the passive input, so it's anybody's guess. That would suggest trying to go through a preamp or an amp that you know has a high impedance input to make sure that's not the problem.
  11. Uncletoad


    May 6, 2003
    Columbus Ohio
    Proprietor Fifth Avenue Fret Shop. Technical Editor Bass Gear Magazine
    Great advice given. My thoughts are similar.
    1. Make sure there is a little gap on the thread side of the adjuster wheel. There should only be wood contact on the non threaded side. Any threaded side contact can lead to weirdness.
    2. Make sure the bridge feet are properly fitted to the top. Not just around the edge but throughout the middle of the bridge foot.
    3. Made sure the side of the bridge that the non threaded adjuster side is installed in is perfectly flat and there is no tilting or leaning across the disc.
    4. Use an impedance matching preamp. It helps a ton. Phase reversal on that pickup cleans up a lot of howling and low end mess too.
    5. Start with no EQ or flat. Roll down the bass knob until the sound seems more balanced.
    That should do it.
  12. Salut Hugo.
    I'm sorry that you're not completely satisfied with the WM12 I sold you, and I hope you don't feel cheated.
    Make sure you plug the pup in the passive input.
    Did you also crank the preamp's volume control so the limiter LED doesn't flash?
    You must be sure it doesn't overload.
    Did you place the speaker switch at the rear at the fullrange or Horn off position?
    Try both settings.
    You can also try to put a foam plug in the rear port. It changes the tone. (gets less boomy)
    I can also lend you a small BOSS FA-1 FET preamp (works on a 9V battery) to make sure it isn't an impedance mismatch problem.
    This preamp has a 3.3 Megohms input impedance.

    Best regards,
  13. Salut François,
    Fear not, no worries on this transaction. This comboamp is not looked after as the problem, it's fine. But then there's this thing i'm more and more understanding as an endless quest : the satisfying amplified sound. This post is to see where to put my energies frist, and up to now, advices are I should work on both sides (verify PUP setup and impedence mismatch effects) :).

    I'm just back from playing around with it. and upto now it sounds fuller when in the "fullrange" setting. the horn off setting is dryer and a bit plasticky to me at the moment.

    These may be other words that describe my reaction to the global sound i'm getting when hookedup: the attack sounds a bit dry and plasticky. Then again, it *does sound acoustic* (that's a good start now aint it).

    more on this later,
    and any comments from users or techies are welcome.
    great discoveries ahead.

  14. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    Get a real long guitar cord and stand out in the room and see what it sounds like. Also have other folks play the bass (especially useful if you know their sound acoustically) and see what's happening out front. It can be surprising how differently things sound at a distance.

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