"Virzi" What does it do?

[Andrew Werner]

Greetings to all!! I'm getting ready to start construction of my "F" and I'm getting as much info as possible. I checked out the photo essay of the Dudenbostel F style and I'm just curious of the actual size and funtion of the Virzi. Also, I've noticed that they are serial numbered in Loar Gibsons. Thanks in advance Drew.


A Mandolin is a terrible thing to taste http://www.mandolincafe.net/iB_html/non-cgi/emoticons/mandosmiley.gif

[Dave Cohen]

Sorry that no one answered you. My simplest answer is that I don't know what a Virzi does. There are advocates of the thing who will tell you that it improves the tone; there are others who despise the things and refer to them as "Virzi tone REducers". I did holographic modal analysis last February on several vintage mandolins, some with the Virzi and some without. I presented the work at the 75th Anniv ASA meeting in NYC last May. I couldn't really tell if the Virzis were doing anything or not. I am going to try again this spring with a "test bed" mandolin with a removable back. I will do the modal analysis sans Virzi, with the Virzi, and with different bracing patterns. Even then, I may not find an answer.

[Darryl Wolfe]

The ones I've seen that appear to be working as planned ..seem to introduce a complex, reflected hum of overtones. Occasionally you can hear a pulsing of amplitude on certain notes

[Andrew Werner]

Well, first let me say that you have to excuse my ignorance on this thing but, like a sound post on a violin, anything that is attached to the top will effect the sound of an instrument. And excuse the comparison, like a restrictor plate in Nascar, I could see how the vibrations entering the sound chamber will be dampened by this thing and then dispersed evenly to some degree out throught the F holes. I read the discussion about these Virzis' on the Mandozine site, and it seems that there is a 50/50 split on the application of Virzis' and how much they affect the tonal qualities of a Mandolin. It seems that people either love them or hate them period. But at present, I have come to the conclusion that I will build a few Mandolins instead of one, and install one in and one out. It would be cool to have a Mandolin that could switch from rythm to lead like the pick-up adjustment switch on a Les Paul. only a dream. hehehehehe.

A Mandolin is a terrible thing to taste:D

[pelone]

Dave---I would be extremely interested in any analysis that you do in regards to bracing patterns and tonal/reverberation comparisons. I am looking forward to your results. I have often wondered how the many patterns might truly affect tonal quality.

[danb]

I played a couple Loars recently, one with virzi, some without. The one example "with" sounded like it was run through very slight compression (take the "spikes" off the tone where individual frequencies are much louder) and also the note was more complex on the bass. The "without" ones have more "punch" and power, and it varies slightly where the spikes are.. D string or G string..

the Treble end (E especially) was consistent accross them, but the low end growl and the puch to them seems to be mostly what the virzi influences. More sustain with the virzi, less of a pronounced "hard" attack (notch down the treble a bit?)

A virzi'd F5 to me is the ideal solo or recording instrument, gorgeous tone and just so much note.. an un-virzi'd F5 has punch and drive and "cuts through" in an ensemble.

To me "F5" means "bass" compared to "F4". Not always true, some oval holed F4s or snakehead As do pretty darn well in that regard.. but generally the F-holes/tone bars seem to me to either produce more bass or be more likely to be designed to get more bass.

Add a virzi to that and you leaven things, and keep the note bouncing around longer. Both sound cool, but for different reasons

[evanreilly]

There is an interesting article floating around somewhere on the 'net about the Virzi. If I remember correctly, it deals with the perceived sounds of instruments of the round-hole and F-hole variety. I beleive the conclusion was that the Virzi focussed the sound differently in both styles, either back to the player, or out the front of the instrument.

[johnwilson]

Here's one way to look at a Virzi:

All musical notes are composed of sine waves which have a specific length determined by frequency. #A low E on an organ measures 32' long and the 440 Hz A is about a foot long. #The higher the note, the shorter the sine wave. #
Reflecting (especially parallel) surfaces are real problems for all enclosures (rooms, mandolin bodies etc.) when the walls are shorter than the wavelengths of the notes being produced. #Sine waves which bounce off reflective surfaces fold back onto themselves. #The joint product of the original and reflected sound results in a cancellation or accentuation of the tones produced.
A Virzi is placed at the thickest part of a mandolin and divides that air space into two differnent sized cavaties. It also includes a vibrating plate of with its' own resonance which tailors the acoustic signature of the instrument.
The Virzi is going to lessen standing (reflected) sound waves at lower (longer) mid range frequencies and produce two new sets of augmented frequencies which fall at the two "new distances" between the Virzi and the top and back plates of the mandolin.

[Darryl Wolfe]

That's exactly what I said John..more complex and "humming" # http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif

Seriously..if you can visualize Johns excellent description, you can hear the difference in your head

[SternART]

From my experience the virzi instruments project out & away from the player, with some loss of actually being able to hear as well from behind the instrument, in the players position. There does seem to be an added complexity of overtones to the sound as well. I know that Lynn Dudenbostel has created some recent instruments with virzis......the others I've played include old F5's F4's and A models. Interesting concept, but the folks who have removed them from vintage instruments, back in the days when they were considered more a tool to make music, than a precious collectable, report increase in volume & responsiveness. These days I think it would be foolish to remove one from a vintage instrument.

[Dave Cohen]

Yeah, except it doesn't work that way. If you had a sine wave emanating from a point ("momopole") source into the cavity, you might be able to talk about reflection. But the air movement in the body cavity of the instrument occurs as "normal modes of motion", just as the wood modes or body modes do. The first of the air modes is the "Helmholtz resonance" or A0 mode, which occurs at about 280-300 Hz in f-hole type mandolins, and somewhat lower in oval hole type mandolins - maybe 220-240 Hz, depending on the soundhole size. There is no reflection involved. It might be described as a kind of "ballooning" motion of the air in the cavity, which in turn sets the air in the area of the soundholes in motion and results in sound radiation from the instrument. The next air mode, the A1 mode, occurs at around 700-800 Hz, and could be described as a kind of longitudinal sloshing motion of the air in the cavity. The next, the A2 mode, is kind of a sideways sloshing of the air in the cavity, and occurs at around 1.1 kHz, iirc. I was the first to measure these air modes in mandolins, but this is really nothing new. It is quite analogous to what occurs in guitars (at lower frequencies) and for that matter in violins, at about the same frequencies.

As I said, I did modal analysis on several pre-1929 mandolins, some with the Virzi, and some without. I also measured the A0, A1, and A2 modal frequencies for each of the mandolins. Sad to say, the air mode frequencies did not appear to be affected (at least not that I could tell)by the presence or absence of a Virzi. What a physicist might expect is that the additional mass of the Virzi would cause some splitting of some of the body modes. Based on my careful holographic analysis, I just couldn't be sure whether I was seeing any effects from the Virzi or not. That is why I need to do the analysis on one mandolin, first without the Virzi, then with.

Now, I don't mean to imply that I am certain that the Virzi doesn't do anything. It may well have the musical effects that are attributed to it. I just couldn't find anything in the camparison of several different instruments.

[Brian Aldridge]

I get to play two loars regularly, one with virzi and one without. SternArt is right on. The virzi'd one kicks out in front of it, but you would swear the non was blowing it away from the players position, but not so. The virzi does round the tone off some, and works like DanB says, compresses it a bit.

[Stephen Perry]

Other aspects to consider are the overall mass of the virzi. The application of this mass at specific points, possibly influencing vibration nodes. Broadening of A0 perhaps. That has been suggested, anyway. I'm going to put one in a fiddle one of these days!

[danb]

giannaviolins:

I guess that's where they started. The Gibson/Virzi fiddles have a slightly more elliptical virzi. I've got pictures somewhere in a repro catalog..

[Stephen Perry]

The original patent drawings and discussion are quite illuminating. Longer and sometimes multistacked plates attached to the bass bar in the upper and lower reaches as well as the center. Attach points in the original (drawing from memory) would tend to ballast the center of the top and to act to stabilize mode 5 (ring mode) vibrations, assuming such things exist in finished instruments. Drawing on the Wright invention (weight in the bar in the upper bout), which actually works, one might anticipate a change in volume and response.

Of course, a mandolin or guitar works very differently. In a violin one has energy pouring in all the time. Not the case with plucked instruments!

[John Bertotti]

I wonder if johnwilson's description would be more in line with a body where the virzi actually vivisected part of the internal air chamber creating a specific longer path for the internal air motion to travel. Much like the theory behind the Bose accoustimass module. Talk about dampening your top though. Did I explain this right? #John

[Stephen Perry]

I don't know if the explanation was right, but I think I got it anyway. An interesting way of looking at it. I read the patent. I recall my response to the description and claims as something on the order of "huhhh???"

[sunburst]

Gianna and/or Steve, thanks for the input.
I haven't read the virzi patent, but maybe I'll look it up. Even if they were way off base in their claims, it might be interesting to get some insight into the thinking that led to the development of the virzi.

My own idea of how a mandolin works is mostly restricted to the air and plate modes. It seems that the mass of the virzi just being there might change something in the way the top behaves, and the physical presence of the thing in there might change the air modes, but I'll wait and see what Dave finds out. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/wink.gif

[Yonkle]

Heres a photo of a Virzi from s 1923 Gibson F5.
Quote:Although the Virzi Tone Producer clearly imparts warmth and tone, many of the Tone Producers in Loar-signed F-5 mandolins have been removed by musicians (or their repair persons) with the goal of achieving more power (commonly referred to as "bark") in favor of tone (an act which Loar would have despised since the air chambers of these instruments were "tuned" with the Virzi Tone Producer in place).