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Double Bass bridge resonance feedback, really weird. (also pickup recomend?)

klocwerk

klocwerk

May 19, 2005
1,644
14
Somerville, MA
www.lordgoogle.com
#1
So I played my upright at full circus-band gig volume last night for the first time (through a 4x10), and was getting insane feedback at like 2 on the amp. I couldn't get enough volume to play over all the horns! It was around 1500hz fyi.
I finally narrowed down the feedback to the bridge itself vibrating! If I grab the right corner of the bridge (next to the E) the feedback stops instantly. If I tap that corner, BWAAAANG!

I solved it temporarily by clipping a pen I had in my pocket to the corner of the bridge, which changed/dampened the resonance enough that it stopped the feedback, but that's not really a long term solution.

Suggestions?

The other side of this is that I'm still using a 10 year old Fishman BP-100, with the piezos clipped right to the top of the bridge. I'm pretty sure that the pickup is a large part of why the feedback was so bad, as the bridge resonance was at the top of the bridge right where the bp-100 clips on.
I've had lots of trouble with this pickup, the response isn't great, and now it seems to be aiding and abeting feedback, so I want to replace it ASAP (first loud gig on amped upright is Sunday, a mere week from now).
I think I've narrowed down my decision to either a Full Circle, or a Revolution Solo II. Any advice on which would be better for my situation? I'm thinking the Full Circle will be less prone to the bridge resonance than the Rev will be, but that's just a gut reaction. Musically it's mostly thumpy oompah type music through my '52 Kay with Obligatos.
 
#3
Johnny Atomic said:
until you can get rid of the BP100, mount it in the wing similar to the way a RS2 or Bassmax is mounted. Use the search function on the BP100 to find out more.

Johnny
Click to expand...

hunh, interesting idea.
I'll try that tonight at home and see if it fixes the resonance, then I'd almost definitley go with a Rev Solo II based on the reviews I've read of it. (Plus fitting a Rev. is a lot easier than tearing down my bass twice, once to measure for metric vs. imperial, and again to install the full circle in the bridge.)
 
#4
Ok, finally had some time to tweak things.
After much fiddling and getting nowhere, i just disconnected the bp100 from the bridge and turned up the master vol again. bwaaaang.
Apparently the piezo's in my BP100 are amazingly good at resonating at around 1300hz, regardless of what they're coupled to.

New pickup time for me, thinking full circle. I went to a show the other night and watched two upright bassists, both with full circles, standing right in front of their stacks with no feedback.
Nothing sells for me like first hand witnessing.
Now to beg and plead a vendor to get it to me asap for this gig...
 
#5
I have not tried the Full Circle on my bass yet. Not willing to part w/ my hardwood adjusters just yet.

But I'm sure you know since it sounds like you've already checked out the threads here that you are probably going to enjoy the FC very much.

Do you have phase reversal on your amp or preamp? Some folks say it makes the FC sound "better". Might be especially useful if you are gonna stand right in front of your rig and/or play at loud(er) volumes. It will probably blow you away coming from the BP-100 regardless.
 
#6
bolo said:
Do you have phase reversal on your amp or preamp? Some folks say it makes the FC sound "better". Might be especially useful if you are gonna stand right in front of your rig and/or play at loud(er) volumes. It will probably blow you away coming from the BP-100 regardless.
Click to expand...

probably picking up a platinum pro eq at the same time.

I dropped a line to Bob Gollihur with the request, and an offer to let him talk me into something else. :D
 
#7
Something to check with the Fishman pickups. Sometimes when the wire to the pickups is stretched tight it can actually resonate and sound like feedback. A few months ago, I was trying to adjust the fit of my RSII and touched the wire...that same feedback like sound...thought I was going to blow my speakers (but didn't)!
 
#8
tornadobass said:
Something to check with the Fishman pickups. Sometimes when the wire to the pickups is stretched tight it can actually resonate and sound like feedback. A few months ago, I was trying to adjust the fit of my RSII and touched the wire...that same feedback like sound...thought I was going to blow my speakers (but didn't)!
Click to expand...

I actually thought of that, I tried gripping the connection, etc. Couldn't get rid of it no matter what I did. It was kind of impressive really. :D
And yes, I've tried different amps/cabs at this point as well.
 
#10
Wow, night and day.
After the BP-100, the full circle and platinum-pro-eq combo was truly a breath of fresh air. The sound was fantastic (a couple band members commented that the bass was much clearer), it was far less prone to feedback, and the phase switch on the plat-pro was incredibly useful for eliminating the bass resonance.

The only downside is that it distinctly pointed out the shortcomings of my speaker cab, so my venerable SWR Goliath II is next on the chopping block. :D
 
#11
tornadobass said:
Something to check with the Fishman pickups. Sometimes when the wire to the pickups is stretched tight it can actually resonate and sound like feedback. A few months ago, I was trying to adjust the fit of my RSII and touched the wire...that same feedback like sound...thought I was going to blow my speakers (but didn't)!
Click to expand...
I've had an intermittent problem with my prototype Paulin EUB - sometimes the open D-string resonates much louder than other notes. Last week we were playing louder than usual and I just couldn't use the open D at all without a huge boom that turned into feedback.
Back home I re-read this thread, then I started applying clamps to various parts of the body, bridge, end-pin etc to see if I could kill a resonant frequency. By chance, I touched the pickup lead and the resonance stopped. There's about 3" of light cable that loops around from my under-bridge piezo to the input socket, and it resonates with a D. A quick temporary fix with a piece of soft foam jammed in it and I'm back to having perfect string balance.
It had me confused because none of the other basses Bill Paulin has made had this problem. However mine was his first prototype, before he figured out a neat way to hide the pickups under the bridge feet and run their connection straight into the control cavity. In my case the wire wasn't stretched tight - it was simply a loose semicircle of cable that just happened to be tuned to resonate with a D!

My bass: Link Removed
My DIY pickup: Link Removed
 

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