A0-B0...Bob Branstetter to the information desk

[Mark Mazurek]

PLEASE Bob!?!?

Everyone is nice here. Even the one's who know the most aren't 'know-it-all's'.


What, where, & how is it used???

http://www.aarhussejlklub.dk/Nyhederne/Billeder/birth-begging-dog.gif

[Ken Smith]

Ok, let's see what pops up here. I don't think Bob want's to get into arguments about this so it might be best that others try this stuff out and report back. The Traeger Book has this stuff in it mentioned in several places. He says that even an old Italian Bass can benefit for it so I have to take that as a real possibility.

For me, I don't know really how this is done but I did read thru some basics about it in his book. The problem is that I like my Scrolls/Gears as they are and also a good healthy fingerboard. ;)

Hey, if the Bass don't sound so good I pick a different one out of the rack..:p

[Greg Clinkingbeard]

I've played two basses that Bob has done this to and they both played well and were very responsive. One being his own and the other, a big Rodier now in the hands of my former teacher. The Rodier is the one mentioned in the article he has made available.
Thankfully, the bow wasn't used but both basses have a very even pizz tone from top to bottom.

The fingerboards don't seem to have been sacrificed on either bass.
My Romanian Hybrid (Upton) has a full thickness fingerboard below the neck (not concave). Bob mentioned that removing the material would be necessary to match A0 and B0. I may just let him go to work on it and report back.

Certainly, for those of us without luxury of just picking another bass a couple of hundred bucks seems like a reasonable expense if it can improve the one we have.;)

And no, I doubt Bob will further involve himself in this discussion.

[David Powell]

The concept is quite simple, but the process of matching is not so simple in that it involves carefully carving out the backside of the FB, removing wood from the neck or scroll, or adding weight somehow. The idea is to get vibrating parts of the instrument to create constructive interference wave patterns instead of destructive or cancelling ones. That way the parts of the instrument are reinforcing the vibrations. The zero modes should be the lowest frequencies so that as many partials as possible are reinforced. By the time one gets into the upper range, most of the notes are a partial of the zero mode frequencies. From a purely physical standpoint, this is intuitive. In practice it is not so simple. The whole instrument has other modes and other parts that also contribute or react constructively or destructively. Even the bow has something to do with resonance.

On my instrument, straight from the maker, the A zero is a "C" resulting in such strong C's everywhere on the instrument that it is possible to get close to a reasonable tuning without a tuner. The tap tone of the fingerboard beyond the overstand sounds like it is also a "C", but a bit above the A zero mode frequency, perhaps two octaves or maybe just one depending on where you strike it with a mallet. This is not matching the B zero, but apparently some makers are tuning parts of the instrument in the building process. Clearly, all the harmonics of the low C, the G's, F's, etc. also are easy to find because they are louder when in tune. On my instrument, this was one of the first things I noticed about it even with the factory set-up, which I improved upon in several ways to fit my playing style. When I dressed the FB, I was careful to take off as little wood as possible to get the job done, and I removed nothing beyond the overstand. I really didn't want to change what the maker had intended. I kept the shavings and these together were very light in weight;- certainly far less than a gram. I don't know if this helped, but the dressing of the board really surprised me in that all the notes everywhere sounded better afterwards. These details gave me a good deal of respect for the makers at Kremona, even if the wood they use for the DB's is not the fanciest, the instrument's characteristics overall suggest a good bit of care went into the dimensioning and design, which is Rubner influenced. As the instrument has opened up, it just gets more and more responsive, to the extent that band mates that remember when it was new comment from time to time. I don't think that resonance matching alone makes or breaks the performance of an instrument, but a great set-up is the combination of a lot of small details adding up, and this can be a boost for some instruments. It didn't surprise me much that small production shops working in the ancient guild tradition pay close attention to the cavity resonance. Like I said, tuning the wood is intuitive, even if one just does it out of instinct and not out of scientific study. It is plausible that the practice predates Hutchins' findings by a couple of centuries or more.

I would go further to point out the partial series of the low BB string resonate in a complementary way to the "C" and tend to balance the response of the instrument as does the E string and A string and other open strings. An instrument built on the foundation of a low C cavity resonance makes sense intuitively.

Balance is the tricky part. Getting an instrument to sound good throughout the range is indeed an art that goes well beyond the science that describes the process. Those that did this without technology that we currently have are the equivalent of Einsteins in my view. Today, I don't think luthierie is what is was in Stradivari's day. The Renaissance makers were breaking new ground. Mersenne (http://members.ozemail.com.au/%7Emacinnis@ozemail.com.au/scifun/sound.htm)had just uncovered the relationships underlying string behavior by studying visible waves in strings (ropes if you please) that were tens of meters in length. By studying in the macroscopic end of the spectrum he was able to establish a foundation for wave behavior that is observed throughout the sound spectrum. Recently it has been observed that harmonic resonance is also involved in the stability of atomic structure. Indeed, it may be the glue of the universe. It is not surprising to note that Mersenne was a contemporary of Amati, and that soon afterwards Stradivari was able to build the quintessential violin. These men were definitely paying attention to the math, though they may not have recognized it as either math or science in the way the modern world views these disciplines. While the word science derives from the ancient latin word for knowledge, Renaissance "scientists" were regarded as "Natural philosophers". They were concerned with the relations of natural phenomena.

Hutchins' work and that of other investigators tends to quantify what was done by these makers and apply it to modern instrument making. Hers was careful detective work over a lifetime of dedication to the concept that there are specific measurable physical relations underlying the making of fine acoustic stringed instruments.

[Matthew Tucker]

Oh.

Have you still got the fingerboard shavings?

[David Powell]

......Yes.

[Mark Mazurek]

Do you have a lighter (and that little pipe)?

[Bob Branstetter]

As much as I dislike getting involved with this again, I find it necessary to correct certain inaccuracies about the A0-B0 matching process that have been posted here.

When we talk about A0-B0 matching, we are actually discussing the process of exactly matching the vibration frequency of the entire neck assembly which includes the scroll, neck handle, machines, and of course the fingerboard with the A0 mode frequency. The goal is to have the entire instrument vibrate together in sync. If the A0 mode frequency is 71Hz, the B0 must be exactly 71Hz to match the A0. Using audible pitch such as the musical note "C" is far too inaccurate to be of any practical value for doublebass A0-B0 mode matching.

Adding weight to or subtracting weight from any part of the neck assembly will influence the vibrating mode frequency of the entire unit. Unlike the scroll and neck, the fingerboard is considered to be replaceable and is frequently modified by planning long after the instrument was completed by the maker. This makes it a very convenient place to add or subtract weight for the B0 mode frequency adjustment. However, when we do B0 adjustments, we are not doing it by changing the tap tone of the unsupported portion of the fingerboard, even though the tap tone pitch probably will change in the process. The tap tone of the fingerboard is the tap tone of the fingerboard - nothing more. Some makers do tune the fingerboard tap tone to a particular musical note, but this is not B0 matching. If I were to swap out the tuning machines with a heavier or lighter set without touching the fingerboard, the B0 mode frequency will change up or down. However, the tap tone of the unsupported portion of the fingerboard would remain exactly the same as before.

The accepted method for finding the B0 resonance mode frequency is to use a high precision sine wave sound generator and a highly amplified speaker to set the neck assembly in motion. To find the B0 frequency, we slowly sweep through a frequency range of about 50 to 100 cycles per second (Hz). This is the range where A0 and B0 are usually are found. The B0 frequency is found when the neck vibrates at it's maximum amplitude. You can easily feel this with the tip of your fingers at the end of the scroll or the end of the fingerboard. In order to match the A0 mode frequency, we usually remove or add weight at the end of the fingerboard, but we could add or subtract weight from the scroll and accomplish the same thing.

[Added 9/19/07 by request]
Before the B0 mode frequency can be adjusted, the A0 mode frequency must be determined. This is the resonance frequency of the air that is contained within the body of the instrument and for all practical purposes can not be changed. For A0, the sine wave generator driven speaker is pointed at the back of the instrument and slowly swept through the 50-100Hz range. An inexpensive Radio Shack ****OG Volume Meter (http://www.radioshack.com/product/index.jsp?productId=2103668&cp=&sr=1&origkw=****og++meter&kw=****og+meter&parentPage=search) is used with an extender to determine the maximum volume amplitude inside through one of the ff holes. If you were to plot the frequency and volume, you would find the A0 to be a very sharp peak. [End]

Because my 1997 paper on A0-B0 matching in basses was written for the Journal of a group of violin makers (The Michigan Violin Makers Assn), I may have made the assumption that the reader would have certain knowledge as a result of them making instruments. Someone who has not made instruments may misinterpret the meaning of certain things. The paper was checked for accuracy prior to publication by MVA Journal Editor David Brownell. David is also one of the co-authors of the Chuck Traeger book and a well known violin luthier. After publication, the paper was peer reviewed by the membership of MVA in a general meeting. In the decade since this paper was written, several freeware and shareware computer programs have become available that will substitute for the sine wave generator and greatly cut the cost of equipment needed to perform this process.

If anyone cares to read the entire paper, feel free to send me an email or PM requesting a copy of the paper. Please be sure to include an email address that can receive a 2.5 Mb document.

[Mark Mazurek]

Thanks for the info Bob.

The explanation was fantastic (for just a guy who own/plays a bunch of instruments). I'm sure the paper would be quite over my head.


If I'm understanding correctly, this would help a string instrument vibrate more freely? It should play more responsively? Or, at least, not dampen itself (or at certain frequencies)?

[Bob Branstetter]

Thanks for the info Bob.

The explanation was fantastic (for just a guy who own/plays a bunch of instruments). I'm sure the paper would be quite over my head.


If I'm understanding correctly, this would help a string instrument vibrate more freely? It should play more responsively? Or, at least, not dampen itself (or at certain frequencies)?The paper was not written written for a bunch of egg head scientists with multiple PHDs. It contains very little theory and it mostly deals with how to do it. I doubt if you would have any problem understanding it.

As to what A0-B0 matching does, I covered some of that in the paper and you can find more information by doing a Google search on "Carleen Hutchins A0-B0" as I suggested in another thread. Sorry, but that is as far as I'm going to go with this.

[Eric Rene Roy]

In the decade since this paper was written, several freeware and shareware computer programs have become available that will substitute for the sine wave generator and greatly cut the cost of equipment needed to perform this process.I'm sure, like basses, everyone will have favorites, but I've always liked this one: SweepGen (http://www.david-taylor.pwp.blueyonder.co.uk/software/audio.html#SweepGen)

[Greg Clinkingbeard]

Eric,
What are your thoughts on this?

[Arnold Schnitzer]

Today, I don't think luthierie is what is was in Stradivari's day.

Agreed. Today there is a higher level of workmanship, on average, than in Strad's day. There is a better understanding of how violin-family instruments work. There is a more open relationship between master luthiers and those with aspirations to become masters themselves. There is a better understanding of wood and wood movement. There is better training and an explosion of useful information-sharing that is propelling luthiery forward.

There is also an explosion of pomposity amongst self-appointed experts who have little if any experience in the field but like to publish huge tomes of self-aggrandizing information on the internet for their own ego gratification.

[Ken Smith]

Agreed. Today there is a higher level of workmanship, on average, than in Strad's day. There is a better understanding of how violin-family instruments work. There is a more open relationship between master luthiers and those with aspirations to become masters themselves. There is a better understanding of wood and wood movement. There is better training and an explosion of useful information-sharing that is propelling luthiery forward.

There is also an explosion of pomposity amongst self-appointed experts who have little if any experience in the field but like to publish huge tomes of self-aggrandizing information on the internet for their own ego gratification.

Arnold, I know you don't use any type of machines to get the results you do. How do you explain your success in restoring old Basses and improving their tones as well as the beautiful mature sound I have heard on no less than 6 of your handmade Basses that I have had the pleasure of playing?

On the great old makers like Strad as mentioned, how do we explain why some of them were more consistent in results while others were less than consistent? I have played two similar Gagliano Basses back to back. Both sweet and even sounding and one of them had been cut down. I have also played two Martini Basses back to back. The first was mine, possible the earliest known (1919) and the other one of his latest (1946). These varied more model wise than with the Gaglianos and only have the FFs and Scroll in common. Mine was much deeper with a sweet low end spread type sound and the newer one was more of a punchy brighter sounding Bass. I also compared my Martini to a G.Gemunder Villuame model. The Gumender sounded more like the later Martini than mine and this was back to back in the same room with my Martini. The Gemunder being about 90 years older was better than the later Martini as expected. Also, I have played two Dodd Basses (not back to back) and they both sounded completely different. One was soft, smooth and deep sounding but not so powerful while the other was in your face, sounding an octave lower than that average Bass and shook the walls when played.

Sorry for the slight rant above but all the Basses mentioned above including Arnold's work were made without any machines to test or alter the sound. All of the Basses mentioned above are great Basses individually. I don't think much could be done to improve them in their current conditions as all of them seemed optimum for the condition they were in fully repaired and the model they were made within.

On the other hand, I have seen some Basses that have been made with at least 20-30% too much wood within the graduation, ribs or linings. Correcting a few of them that I was involved in greatly improved them. Could AO-BO matching have gotten these same improved results or does going to the 'knife' make the only sense in getting the job done?

[Greg Clinkingbeard]

There is also an explosion of pomposity amongst self-appointed experts who have little if any experience in the field but like to publish huge tomes of self-aggrandizing information on the internet for their own ego gratification.
:confused:

[Ken Smith]

In talking back and forth with Bob B. we discussed the fact that many people here and over at TB have drawn conclusions simply by reading and judging but not actually trying it. This I think is close minded.

I am not saying that Arnold or Jeff must use AO-BO matching when they work on my Basses because they do get good results using the methods they know. What I am saying is that those that want to try using this method of fine tuning, do so and then report back.

I am sure Bob will help coach and answer any questions you might have but it is not good to mock what you havn't been tried or experienced personally.

Bob has also offered to send the documents he has on the subject free of charge if you just message him privately.

Please respect Bob's wishes to stay clear of the public discussion or rather debate as he does not wish to argue the subject.

This Thread is for discussion, question and tried results mainly and not to bash what one has not tried. Keep it peaceful.. thx..

[Matthew Tucker]

I don't think much could be done to improve them in their current conditions as all of them seemed optimum for the condition they were in fully repaired and the model they were made within.

But how can you ever tell that no further improvement is possible?

[David Powell]

Do you have a lighter (and that little pipe)?
If you've ever gotten a good wiff of ebony dust, you would know that this is not something that one would consider, though it might look tempting. :eek: It burns your sinuses without being burned. But you know, I probably should label that little plastic box those shavings are in. Some pilfering idiot could make a serious mistake.

Doh, what kind of ebony is that? Looks like Afghani? Hmmm. choof. swwoOOOOOoppp. PUH, PUHG, AAAAAAAGGGGGGGG!

I keep the shavings in case I need to patch something.

I knew if posted a mistake, Bob would rescue the method! ;)