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Double Bass flatback resonance and f hole resonance?

orbit2021

orbit2021

Mar 12, 2009
65
0
42
Spokane, WA
#1
My DB is a 1920s era german flatback and i have a realist pickup in it. i have noticed that when i mute the back of the bass by sitting on a stool and rest the back of the bass flat against my left thigh that i get a MUCH better response while playing through my amp, because the back of the bass resonates and even can start to create feedback if my tone settings/eq arent set up very well. i also had my friend cover the f holes with his hands and also noticed a bit of an improvement in clarity/response.

do any other flatbackers have this problem? and if so, how do you combat it?

at first i thought the pickup was just NOT going to work out but when i discovered these two things and when i make an effort to reduce those things it sounds MUCH more viable through my amp.
 
#2
I have a flatback and I don't have that problem. I have a full circle but I used to have a realist. The feedback your getting makes me think your amp is too loud. Most of my "amping problems" start at the beginning of my signal chain (ie my technique). If you are playing jazz in a small group, you shouldn't need that much amp. You probably shouldn't need to EQ it too much either (most amps seem to work well with the EQ flat at lower volumes). If I were you, I would think about your "unamped" sound and how you can make it better. It doesn't seem like covering the f-holes or holding the back of the bass against your leg would be good for a strong acoustic sound. Also, if your bass is like mine, it is louder out in the room than when you are standing right next to it. So you might turn the amp volume down until you can barely hear it, and see if the people you play with tell you to turn up. When your volume is low, you have to concentrate more on getting a good sound. If all else fails, try a full circle. So far, it is by far the best pickup I have used. Hope this helps.
 
#3
well unfortunately i dont play in a quiet group, not that we are very loud, but certainly loud enough for me to warrant needing the amp.

when i said feedback, i didnt mean full on feedback, but that there is a fairly noticable amount of resonance that muds up the sound quite a bit. also when i say mute i should say dampen, because im basically just stopping the bass from ringing when the strings are not. i have even separated myself from the amp quite a bit, using about 40" of cabling (2x 20ft connected thru my baggs para DI) and so it seems like it is less the resonance from the amp and more the resonance of the bass itself being too much for the pickup?

my bass is quite loud, its a 7/8 (not attributing the loudness strictly to the size), and i have even noticed that acoustically (unamped), muting the back can be beneficial when i am playing arco and need a quieter more focused sound....not to say that if i was a better player that i couldnt produce the sound i needed without muting the back, but overall the back is very resonant.

when comparing the thickness of the back to that of my friends non flatback, (carved back?) its roughly half as thick, but i assume this is to be expected. anyways as i said the back is simply very resonant.

also the thing is, when i mute the back when i am amplified, it really sounds great to me, its just that i have to play with a stool to achieve that.

i was thinking of maybe some way to mute the back with a material method but the first thing that came to mind was how you might dampen a kick drum, with some material and some duct tape but OF COURSE i would never subject my bass to that!

any other flatbackers with any experience like this? if there are none, then i would like to hear from flatbackers who have success to show me that i am in the minority/unique situation.

EDIT: also as far as EQ, its basically flat with some mids and lows cut (as i said its a loud and boisterous bass).
 
#5
I could be all wet, but I don't think I really have seen any delineation or patterns in this forum w.r.t. amplified DB for round v. flatback basses.

Joel's points in his first post were excellent, BTW, IMO ...

If your bass is really resonant, that will probably make it harder to amplify. But if it gets a big acoustic sound, that's great! Don't change it. :) If it still sounds too resonant with that 40' cable like you said, yeah maybe your bass does not like the Realist so much.

Anything happen if you dampen the afterlengths? That's an easy, non-instrusive mod.
 
#6
I have a round back bass and I noticed the same thing. I play in a country band. We're not as loud as most country bands but it's still louder than most jazz groups. I noticed if I bend my knees a bit I can rest the bass against my left knee while standing and this cleans up the sound a lot when it gets loud! In extremely loud circumstances (rock bars with 500+ screaming fans) I sometimes put foam in the F holes and this reduces feedback a lot. For less extreme measures, dampen the afterlengths of the strings and put a piece of cloth or foam between the tailpiece and top of the bass.
 
#10
In my experience, the Realist is a great pickup for low to low-medium volumes. As the volume ramps up, however, the instrument's own resonance or lack thereof becomes an ever-increasing factor. At that point, I think the FC becomes the better choice. Ultimately, though, the double bass at high volumes becomes a very efficient feedback generator. In that situation, I'd go for a magnetic pickup or EUB. There's at least one long thread on this subject on TB.
 
#11
thanks for the feedback salcott. im thinking that the contact with the body of the bass itself makes the natural resonance more of a factor. my buddy has an underwood and i would like to try that to see if the resonance is less of a factor.

feedback i dont really have any issues with until i hit a certain note if im playing at quite a higher volume, its mostly just the resonance...even after muting the strings the bass will continue to resonate unless i am dampening the back of the bass.

i wonder if there would be someone on the board willing to trade a full circle for the realist, they appear to be within 10$ price difference.
 
#12
I agree with Salcott. I also don't think anyone who's tried a Full Circle would want to trade it for a Realist. I've used both, and to my ears the Full Circle is miles ahead.

That said, I have two NS LaScala basses - one a hybrid roundback, one a laminate flatback. The laminate sounds louder, the hybrid sounds better in terms of complexity of tone and evenness. When I first got the ply, I had some issues with resonant frequencies which drove me nuts. I was doing all kinds of obsessive things like positioning a miniature "second soundpost" (about the size of a pencil) from the bottom of the fingerboard to a spot on the top which dampened the frequency that was driving me nuts. Dampening the back with my leg (I'm a diehard sitter) also helped with the "focus" of the sound. Either way, the resonance was much worse amplified that unplugged.

I can't remember what happened after that, except that I realized that the hybrid is the perfect bass for me, and that judging every bass against it would be like measuring every woman I met against Juliette Binoche - I would be continually disappointed that no one measured up. Rather than being disappointed with every other bass in the world, i decided to appreciate the one I had instead. Since then, I've focused on learning to make the ply sound as good as I can when I use it (it's my office teaching bass), and in this regard I've discovered that it's a great sounding bass. John Goldsby recorded a great live record using it with a set of new strings and a cruddy amp, and it sounded brilliant. I've played a few clinics and concerts with it at the U, and never notice the frequencies any more. Either they're gone, or I've learned how to play the bass. Either way, I'm happy. BTW, both basses have a Full Circle on them.

To summarize: try the Full Circle, and experiment with dampening the afterlength while amplifying. Strings with higher tension, or strings jacked up higher than you normally would, will increase the tension on the plates and tighten up the sound. Technique trumps all of the above in the end.
 
#13
Chris Fitzgerald said:
Technique trumps all of the above in the end.
Click to expand...

+1

I have a flatback and a Realist. Works great for me. There is something about the Realist's ability to transmit the thump that I've never heard from any other pickup. I rented a bass one time that had a Full Circle and it was a much more complex tone, I could see myself liking it, but that thump was missing. I am all about the punch in the gut. The Realist does that best IMHO.

I played a big rock club the other night and with the HPF and the phase switch on the Fishman Plat Pro it didn't have to dampen anything. Worked great. Even the soundman, who did a great job, commented on how huge and clean a tone I got.
 
#14
fingers said:
+1

I have a flatback and a Realist. Works great for me.
Click to expand...

Yeah, but you're a freak with a dark soul patch and a serious groove face. Not everybody has these advantages.

Seriously, it just goes to show that every bass and every player is different. To the OP - find the baddest player you know and see if you you can get them to play your bass and stand out front and walk around while they do it. I bet it sounds like the player regardless of the resonances.
 
#17
fingers said:
I played a big rock club the other night and with the HPF and the phase switch on the Fishman Plat Pro it didn't have to dampen anything. Worked great. Even the soundman, who did a great job, commented on how huge and clean a tone I got.
Click to expand...

I agree. A high pass filter and phase switch can really help. Is there only one frequency that feeds back? Are all the notes ringing if you don't stop them? If it's just the one frequency and it's louder even unamplified it's probably the bass and will still be there with another pickup. Different pickups do seem to work better than others for this though. You could try a notch filter to try to dial it out. I've noticed that at loud volumes the pitch that my fingerboard or tailpiece resonate at are louder than other notes. I used to have a problem where my tailpiece would ring at a pitch somewhere between G and F#. When I played the open G it sounded like 2 g strings being played but one was a quarter tone out! Not nice. Since I started muting the tailpiece this is not a problem. If you don't want to do that try the notch filter.
 

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