Anybody have experience with cello pickups?

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LupineSound
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Anybody have experience with cello pickups?

Post by LupineSound » Tue Mar 18, 2014 6:24 am

This may not be the best forum to ask, but maybe one of you have experience with this.

I'm trying to record a cellist through a loud amp (V4) and fuzz pedal. It sounds great amp'd but as soon as we engage any sort of overdrive/distortion, the cello feeds back. I've tried noise suppressors but that made the phrasing sound unnatural at times. I think maybe it's time to try a different pickup. I'm currently using "The Band" which was supposed to be the best for feedback control, but it kinda sucks. The only artist I know who does something similar to what I'm trying to record is Helen Money, but I can't figure out what pickup she's using. Any ideas?

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Post by ubertar » Tue Mar 18, 2014 6:57 am

I've made electromagnetic and electrodynamic pickups for cello and violin that work well. My email address is on my website: http://www.ubertar.com/hexaphonic

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Post by ubertar » Tue Mar 18, 2014 6:59 am

A quick fix in the meantime would be to record through the amp, clean, then re-amp for overdrive/distortion.

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Post by losthighway » Tue Mar 18, 2014 7:06 am

Can you put the amp in a different room? Also the reamp idea is good.

I guess that's why some of the rockers that play bowed instruments end up getting those weird solid body electric violins/cellos.

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Post by ubertar » Tue Mar 18, 2014 9:24 am

Hey... I just tested out one of my new low-impedance coils on my cello, and through a low-to-high Z transformer to an amp about two feet away, it sounded great, with no feedback, with the amp on 12 (all the way up). The amp is a Champ, so not very big, but still...

For the full pickup, each string would get its own coil, and the signals would be summed together into the transformer. Or if you wanted, they could be taken separately and recorded direct, to separate tracks.

It only worked for two of the strings-- the others weren't ferromagnetic enough. So the cellist would have to be ok with getting strings that work well with electromagnetic pickups. I know with violin those are often the cheapest strings, so expense isn't an issue; it comes down to whether they like the sound for when they're just playing acoustically.

My high-Z coils would work for this, too, but there's a drop in volume as more coils are added together... I haven't tested yet summing the low Z ones pre-transformer, but I don't expect that to be a problem for them.

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Post by thunderboy » Tue Mar 18, 2014 10:01 am

Melora (Rasputina) uses/used a K&K Twin Spot. Relatively cheap and easy to install, handles distortion well.
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Post by ubertar » Tue Mar 18, 2014 10:06 am

Just did another couple tests... four low Z coils in series, and four in parallel, pre-transformer, and both worked very well, with nice tone and no feedback issues.

The only remaining question is mounting, and I have a design in mind for a simple mount that's non-permanent and easy to put on and take off.

I've got other work to do, but let me know if this interests you and I can do it.

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Post by LupineSound » Wed Mar 19, 2014 1:59 pm

Thanks for the replies, everyone.

I hadn't thought of re-amping, that'd obviously work, but ideally I need to find something that would work live.

Ubertar, that sounds super interesting. We've tried three different pickups now with less than stellar results. I was thinking that a cello pickup that was more similar to a guitar pickup (individual coils, mounted right under the strings) would probably work best, but surprisingly nothing like that exists, that I know of. So yea, I'm very interested. Let me know what you think it would cost. Thanks!

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Post by ashcat_lt » Thu Mar 20, 2014 8:47 am

You didn't actually say what sort of feedback you're getting. If it's actual resonant/string feedback, then changing pickups ain't really gonna help all that much. The instrument is specifically designed to resonate and reinforce its own vibrations, and if you're then reinforcing that via an amplifier, the thing just takes off and heads for infinity. I've seen acoustic guitars create a sort of feedback even with the strings muted. The body itself was vibrating and taking the pickup with it, and from the point of view of the pickup it doesn't matter if the string is moving or it is...

So basically if it's not a problem of microphonics in the pickup itself (the pickup off and away from the cello doesn't feedback on its own), then you will need to do something to damp the resonance of the instrument. Sometimes closing the soundhole on a guitar can help, so maybe duct tape the f-holes shut? Else stuff the whole thing with dirty socks or something. The acoustic sound of the cello will be affected, but the amp sound should still be acceptable. Yes, this is exactly why solid body electric cellos exist.

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Post by ubertar » Thu Mar 20, 2014 9:47 am

Changing pickups can help a lot. There are a number of reasons for this. The OP didn't say what kind of pickup they are using, but most pickups for acoustic instruments are piezo.

Piezos respond to changes in pressure. They're the usual choice for acoustic instruments because by detecting changes in pressure, they can pick up the sound from the body and not just the strings, resulting in a more natural sound (the frequency response isn't flat, though, so it does color the tone... there are also impedance issues, and most piezos use active circuitry to deal with both those issues). Because they pick up the vibrations of the instrument body, they can be prone to feedback.

Electromagnetic pickups respond to changes in the electromagnetic field of the pickup (the vibrating ferromagnetic string cuts the lines of flux in the field, inducing a current in the pickup's coil). They're very similar in design to a moving coil dynamic mic, but the coil is fixed in place. The pickup will be microphonic to the extent that the coil's windings are allowed to move. Since the coil is not exposed to air, only an extremely microphonic pickup will be sensitive enough to feed back when it's not touching anything. The looser the coil is wound, the more it will vibrate along with the body of the instrument, and the more prone it will be to feedback. How it's mounted also comes into play. If the coils are potted, there should be little to no microphonic quality to the pickup, and little chance of feedback. You'll only get the string's vibration, and not the body. Of course, if the strings themselves are vibrating like crazy and feeding back, the pickup won't matter. But that's pretty unlikely, IMO.

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Post by ashcat_lt » Thu Mar 20, 2014 2:21 pm

Yep, if the body shakes and makes the strings shake then it doesn't matter what kind of a pickup it is. Also, though, as I said, if the pickup is mounted in such a way that it moves with the body, and the body manages to move indepently of the strings, you'll get a somewhat different sort of feedback.

Poorly potted pickups will of course cause all kinds of ugliness, and I don't think they need to be all that bad to do it. Sheer volume will make about anything that can break loose do so, and compression/overdrive/distortion will always exacerbate the situation.

I'm really not trying to argue. IMO magnetics are the better answer in this situation for a number of reasons. I'm just saying that if you've got distortion, and an amplifier in the same room as a resonant instrument like a cello, you almost have to accept a certain amount of feedback or some sort.

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Post by LowG » Fri Mar 21, 2014 7:10 am

I have plenty of experience with this. The advice given so far is good though. Fuzz with any piezo will not be useable live. If you must use fuzz, then only a magnetic pickup will work. But try overdrive or distortion; that will often be ok with certain piezo pickups and may be "enough" distortion. After all, many use fuzz for the sustain and the bow takes care of the sustain with a cello.

Going the direction you are, no single pickup will do all you want - each will have strengths and weaknesses. Experiment and you'll find your voice within all of that.

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Post by LupineSound » Fri Mar 21, 2014 11:25 am

The pickups we've tried so far are Fishman (not sure the model), which was horrible, and Headway's "The Band" pickup, which is not as bad, but still tricky. I hadn't thought of filling the sound holes.

The craziest part, to me, is that we actually tried having her sit behind and away from the amp and it still fed back. I just did some research and the pickup we're using is a piezo. Shit. I think electromagnetic would be the way to go. I'm pushing for her to have Ubertar make her a pickup cuz I think that would be awesome, but it's ultimately up to her.

Seems like a lot of effort but hearing that cello through my Ultimate Octave and a little bit of the V4's reverb is just glorious. I'm stoked to get a good recording of it.

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Post by LowG » Fri Mar 21, 2014 1:32 pm

Just to experiment, if you have a P-bass hanging around those split-coil type pickups work out pretty well for arched bridges: use one for the low two strings and one for the high two. You could just borrow the pickup for a bit and see how it works just for fun. If the player likes it it might encourage an investment into a more refined version like was suggested earlier in the thread.

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