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DGV

What is on the cello belly?

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I don't know, but I saw one a while back and asked the same question you did.  I guess if you had a 'cello you liked and it had a wolf that made you crazy I would give it a try.  I really only played 'cello and bass in college and when I needed to when teaching orchestra so I really do not have that much experience with wolf tones.  I never had any big problems with my instruments (probably because I am not good enough or because I did not play hard enough literature )

 

 

DLB

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Thanks Dwight.  A $150 wolf eliminator must work, right? :D

 

Probably exactly the same as a $5 set of magnets coated in plastic.

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My son's cello has a wolf note.  And I have a couple of round magnets.  I should see if it removes the wolf as well as the $20 wolf suppressor that I bought for him a couple of weeks ago.  Will report back once I have a chance to get to it.

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I believe the portion inside the instrument has a cylinder containing a sliding magnetic piston, opposed by other magnets at each end of the cylinder. Piston kinda floats in that magnetic field.

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The Krentz wolf eliminator works better than anything I've ever tried for really strong wolfs. I was super skeptical until I tried it and now I think it is one of the best of the solutions out there.

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Previously I thought the German made one that you glue to the inside of the cello was the best option but I don't even carry that anymore because the Krentz works so well.

Certain orchestras will be full of them. If you watch the Seattle Philharmonic, you'll notice the whole cello section with them. I think NY Phil is the same.

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Here are photos so you can see it's more than just a magnet. I tried to separate the magnet for the second picture, but it started shooting back together as I was taking the photo, so it's blurry.

I'm not connected in any way to Krentz. I don't get a kickback or anything, I just think it's a good product and I would like to see them make enough money to keep selling it. I've already decided if they go out of business, I'm keeping the last couple I have in inventory for whatever cello I'll be playing at the time.

post-29575-0-77311500-1432319164_thumb.jpg

post-29575-0-29695500-1432319216_thumb.jpg

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They have one for violin and one for viola.

 

I am happy to report that my magnets work as well as the $20 wolf suppressor. But I don't think I will spend $150 on a wolf eliminator when the cello is only $400. :D

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The Krentz works better on my acoustic cellos than anything else I tried. I have 2 acoustic cellos and 2 Krentz WE's. Each Krentz cost a lot less than a full set of new strings.

My third cello has no wolf whatsoever (so yes, it is possible) but-- it is a Yamaha silent cello.  Wait a minute-- sorry, you said good-sounding cello..oh well.

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Is it possible to make a good sounding cello that doesn't have any wolf note?

I don't recall running into one. Some wolves are less noticeable than others.

 

What is the working principle behind the piston dealy? 

It's basically another design of a vibration dampener. It absorbs energy at the target frequency, reducing the amplitude. Most are a weight attached to some kind of spring (including the ones which are a weight attached to the string afterlength), tuned to oscillate near the frequency you are trying to dampen. In this case, I guess the "spring" is a magnetic field, or at least that's the way it appears to me without having taken one apart.

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What is the working principle behind the piston dealy? 

 

It's basically another design of a vibration dampener. It absorbs energy at the target frequency, reducing the amplitude. Most are a weight attached to some kind of spring (including the ones which are a weight attached to the string afterlength), tuned to oscillate near the frequency you are trying to dampen. In this case, I guess the "spring" is a magnetic field, or at least that's the way it appears to me without having taken one apart.

 

I was not familiar with these things until this thread.  Just from the photo and other clues, I come up with a little different version of how it works.

 

The mass/spring eliminator, such as the weight on an afterlength, or adjusting tailgut length, work by tuning the mass/spring precisely to the exact frequency of the wolf in each individual instrument.  It is a non-radiating resonator, which (in a nutshell) takes on the energy which would otherwise go into the instrument.  It's more complicated than that, though, and if the tuned frequency and wolf frequency aren't matched precisely, the wolf can be made worse.

 

The Krentz is not tuned, and can not be tuned to each instrument.  So it can not be a non-radiating resonator.  Besides, the large mass and apparently soft magnetic suspension are unlikely to get its resonant frequency up into the range needed.  

 

My conclusion is that the suspended mass is essentially stationary, and adds damping (via air pumping around it) as the rest of the assembly vibrates with the instrument.  It should have the most damping at large displacement, lower frequencies, and less at the high frequencies.  You still have the mass of the attaching magnets and tube assembly; I don't know if the pad on the assemblies are just to protect the instrument surfaces, or if they perform some form of high-frequency isolation to disturb the high-end response as little as possible.

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Don,

I talked to Robert Young a couple years ago at Oberlin when they were developing the wolf eliminator. Actually my first experience with the device was with the prototype. Apparently it is tuned to a range of problem notes. I don't know what that means technically speaking.

The only thing I know is how it works when I play. I've tried just about everything out there. The on the string weights I find to be very ineffective. Often they dampen the whole instrument and take the wolf down slightly but it's still there. To get the most out of them, I tune them like David talked about in an earlier post. The German made wolf resonator seems to work pretty well. The one where you use putty to locate the best position on the outside of the instrument first and then glue it in later on the inside (some players just leave them on the outside indefinitely). It seems to target the wolf and not dampen the rest of the instrument as much. The Krentz works a lot like the German wolf resonator, only more effective. It seems to focus the tone and makes the wolf very manageable. I would actually say the wolf goes away in most cases. I don't see a lot of dampening of the whole instrument. Again these are my observations as a player. I don't have any measureable data to offer in any scientific way. I would like to know exactly what's going on with theses devices though.

From observation though, I don't think we should discount the product because it does seem pretty effective. It would be nice to know what's technically happening because maybe it could even be improved upon.

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It seems most wolf notes on the cello are between E and G#, maybe that is the target range?

It is tuned to a range like that, yes. I don't know what it is they technically do to tune to that range though. It would be interesting to know.

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Is it possible to make a good sounding cello that doesn't have any wolf note?

I believe that instrument would be in contravention of the Laws (as opposed to Suggestions...) of Physics as we now know them!

 

I've done some work for Kevin, and seen the wolf modulators/suppressors, and they are worth every penny, or, err, dollar that you pay.

 

Also, I think that part of his idea is that you will slide the device out to the edge when not needed, lessening the effect it might have on the overall sound of the instrument.

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It is tuned to a range like that, yes. I don't know what it is they technically do to tune to that range though. It would be interesting to know.

 

I can't see how you can "tune to a range" effectively.  You can have non-linear springs (which magnetic suspension would probably be), but that would change the "tuning" depending on how loud you play.  I still think it's not really tuned, just damping large displacement movements.

 

If anyone has one of these things to send me for non-destructive testing, I'll be happy to mess around with it and report back what I find.  I'll send it back, of course.  PM me.

 

Edit:  Offer taken.  I'll post results eventually.

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I believe the portion inside the instrument has a cylinder containing a sliding magnetic piston, opposed by other magnets at each end of the cylinder. Piston kinda floats in that magnetic field.

 

And moving inside a bit of air,  it ought to work just like a shock absorber on your Harley.  And perhaps the rubber coating on the outside is a rather lossy stuff.  By the way,  bought a Goldwing a year or so ago and love it.   Too bad it does not make any noise :) 

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I can't see how you can "tune to a range" effectively.  You can have non-linear springs (which magnetic suspension would probably be), but that would change the "tuning" depending on how loud you play.  I still think it's not really tuned, just damping large displacement movements.

 

If anyone has one of these things to send me for non-destructive testing, I'll be happy to mess around with it and report back what I find.  I'll send it back, of course.  PM me.

 

Edit:  Offer taken.  I'll post results eventually.

 

Please compare with $5 magnets as well while you're at it.

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