|
|
Joined:
August 2008
Posts: 90
Location: los angeles | Just looking at a thread on another forum and a discussion with luthiers on sound ports. Question: Has anyone ever tried cutting a sound port into the lyracord, and if so, what result? Many thanks in advance?
Bob |
|
| |
|
Joined:
May 2006
Posts: 4236
Location: Steeler Nation, Hudson Valley Contingent | Why cut a new hole in a perfectly good bowl just for experiment's sake. Just pull the can from any of the "bean-style" pre-amps in recent Ovations and...POOF!...instant sound port!  |
|
| |
|
Joined:
March 2002
Posts: 15680
Location: SoCal | Somebody did it to one of their guitars a few years ago and brought it to a factory gathering. I wasn't impressed with the results.... |
|
| |
|
Joined:
April 2009
Posts: 130
Location: London, UK | Ovations have sound ports. Always cut in the 'top' of the guitar. Some have one big one, others many smaller ones. They do indeed enhance the sound and don't look too bad either, by all accounts. |
|
| |
|
Joined:
February 2002
Posts: 5750
Location: Scotland | Errm, no. The definition of a "soundport" is an auxilliary soundhole in the rim of the guitar, the purpose of which is to direct sound towards the player. As opposed to a soundhole (or soundholes) the main purpose of which is to determine the fundamental frequency of the body cavity. Soundports kinda work. I can happily live without them.
If you add soundports to the rim then the main soundhole should be proportionally smaller. Some luthiers use standard-sized soundholes in conjunction with side soundports, and that's not a great idea. |
|
| |
|
Joined:
March 2002
Posts: 15680
Location: SoCal | Originally posted by Paul Templeman:
If you add soundports to the rim then the main soundhole should be proportionally smaller. Wouldn't that also reduce the amount and type of sound projected forward? Also, would the sound the player gets thru his sound port be a good representation of the sound of the guitar? The reason I ask is that when you use feedback busters, don't you change the acoustic sound of the guitar? |
|
| |
|
Joined:
September 2007
Posts: 153
Location: New Jersey, USA | I have a custom made flamenco/classical hybrid with a 1" sound port on the side near the neck joint. It is a positive enhancement, but it is subtle at best. It gives the impression of a bit more "air" or spaciousness to the sound.
This is noticeable when A/Bing the sound while covering and uncovering the opening. Otherwise, again, it's nice but subtle. |
|
| |
|
Joined:
February 2002
Posts: 5750
Location: Scotland | Originally posted by moody, p.i.:
Wouldn't that also reduce the amount and type of sound projected forward? Also, would the sound the player gets thru his sound port be a good representation of the sound of the guitar? The reason I ask is that when you use feedback busters, don't you change the acoustic sound of the guitar? [/QB][/QUOTE
A feedback buster raises the resonant Freq of the box, the upshot of which is that bass response is reduced somewhat. The effect of closing the soundhole (or making it slightly smaller or larger) on acoustic output and projection is negligible. A perfect example is single Vs double epaulete Adamas guitars. The physics of stringed instruments is generally misunderstood. Remember that a soundhole is just a tuning port rather than "the place where the sound comes out" as many people perceive them. The entire box countributes to producing and projecting sound, not just the hole.
Soundports tend to give the player enhanced highs rather than an entire picture of the guitar. There's no reason why a soundhole in the top could be eliminated and the primary soundhole located in the rim. |
|
| |
|
Joined:
March 2006
Posts: 1634
Location: Chehalis, Washington | I only have experience with one guitar with a soundport, and based on this select sample I am sold on the concept, properly worked. My Cornerstone is very loud, both to me playing and in overall projection, and the tonal balance is spectacular.
Here's an article that another custom builder did on some testing of soundports:
McKnight Guitars Sounport Test
That said, I don't know that you could do that on an Ovation anyway, since the slope of the body is designed specifically for forward projection. |
|
| |
|
Joined:
August 2008
Posts: 90
Location: los angeles | But aren't box guitars also designed for forward projection? |
|
| |
|
Joined:
September 2006
Posts: 10777
Location: Keepin' It Weird in Portland, OR | Yes, but the flat back of a wood-box guitar vibrates much like the top soundboard of the guitar.
(except that the rear bracing is much different and the wood may be thicker)
Whereas the bowl of an Ovation does not vibrate as much, and it is not flat like a wood-box. |
|
| |
|
Joined:
February 2008
Posts: 747
| Originally posted by Old Man Arthur:
Yes, but the flat back of a wood-box guitar vibrates much like the top soundboard of the guitar.
(except that the rear bracing is much different and the wood may be thicker)
Whereas the bowl of an Ovation does not vibrate as much, and it is not flat like a wood-box. Not to dispute what you're saying Arthur, and just as an aside; to get more out of my 1621-4 I sometimes hold it so the back doesn't touch my gut - gets a much sweeter sound that way - the guitar, not the gut..lol |
|
| |
|
Joined:
February 2002
Posts: 5750
Location: Scotland | Originally posted by Old Man Arthur:
Yes, but the flat back of a wood-box guitar vibrates much like the top soundboard of the guitar.
Another example of how the physics of stringed instruments is misunderstood. A soundboard is under something approaching 200Lbs tension which through the twisting forces applied via the bridge goes through very complex vibrational modes. The back by comparison is not under the stress of string tension and consequently vibrates much less and in completely different modes. The materials used for the back and sides will influence the tone a little, but a guitar's tone is generated mostly from the top. To suggest that an ovation bowl "vibrates less" than a wood guitar is nonsense. Fibreglass vibrates "differently" to wood, just as mahogany vibrates differently to maple. |
|
| |
|
Joined:
March 2006
Posts: 1634
Location: Chehalis, Washington | It's more shape and interior volume, as I understand it. Just as a shallow-body Ovation has less overall volume and projection than a deep-body, a round-back guitar will naturally have a different dynamic to it's sound than a flat-back guitar. It would be like going from a slim-body acoustic to a super-jumbo. Apples and oranges.
I just don't think that with the unique design that Ovation put together 40 years ago for their guitar backs that you could cut a soundport and have it actually work correctly. |
|
| |
|
Joined:
December 2004
Posts: 581
Location: Denmark | Adding a port on the back is fairly easy with multi soundhole models - just remove the back cover. Doing so will acoustically short cicuit the bass and the sound gets thin as a fashion model. |
|
| |
|
Joined:
December 2004
Posts: 581
Location: Denmark | Regarding the bowl I believe that the bowl is supposed to promote a forward projection of sound energy - which it does - and provide structural strength - which it does - and provide a shape being comfortable to play - which (I find that) it does. |
|
| |
|
Joined:
February 2002
Posts: 5750
Location: Scotland | Originally posted by tpa:
Regarding the bowl I believe that the bowl is supposed to promote a forward projection of sound energy That's called marketing. |
|
| |
|
Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | tpa : det er da en reflektor |
|
| |
|
Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | Sorry , will keep it in English.
The air-mass of a chamber of a given volume will , when brought into movement , cause the chamber to oscillate at frequencies according to chamber`s internal size ( that is where the chamber likes to oscillate ), when chamber is say , of the following sizes :
H = 50 cm = 650 Hz
W = 40 cm = 850 Hz
D = 12 cm = 3000 Hz
( These sizes are the biggest measurements of a dread.)
So this chamber likes to BOOST freq. between 650 Hz. - 3000 Hz.
The shape of a guitar will cause an even more complex variety of Phase-shifts than an Oblong cabinet , coupled to a carefully placed duct/port/slot , a carefully adapted bracing and balanced strings ( gauge , material etc. ), a more or less evenness of sounds can be obtained ,
at certain tones , rather magnitude thereof , things go bonkers , causing a phenomena , known in the musicworld as " wolftones " , the Ovation guitar has a clearly defined reflector as it`s backplate ( causing a rather good forward projection ) hence , the testimony of many commenting on " this ax plays LOUD " , some other gits. have arched backplates too, albeit not as pronounced.
I have played my 1537 without it`s back-hatch ( keeping it well away ) , and there`s not that much difference in sound , not really louder , no higher clarity ,perhaps a little " muddy " ,without true loss of bass , after all , bass-cancellation occurs at lower freq. than an acoustic git. generates .
All in all , so-called porting will cause " leakage " , but without drastic results.
It`s a matter of perception.
Vic |
|
| |
|
Joined:
May 2008
Posts: 4996
Location: Phoenix AZ | My money is on Helmholtz.
Ringside seats still available. |
|
| |
|
Joined:
February 2002
Posts: 5750
Location: Scotland | It's not a matter of perception, it's a matter of acoustic physics, which remains a fact no matter how ridiculous your perception may be.
Please, explain to me in scientific terms exactly how this "reflector" you describe actually works.
Just because the dimension of a guitar relate to certain frequencies does not mean that the frequencies in that range will be boosted. Certainly standing waves may be propagated at those frequencies (and their related octaves) but standing waves may cancel or they may reinforce depending on phase. Stringed instruments follow Helmholtz principles and in most guitars the fundamental (or Helmholtz Frequency) of the air chamber is tuned to somewhere between F# and A (93Hz to 110Hz) way below the 650 to 3K range you allege.
Also, I'm confused by the phrase "bass-cancellation occurs at lower freq. than an acoustic git. generates" What the hell does that mean? |
|
| |
|
Joined:
March 2002
Posts: 15680
Location: SoCal | I don't think I'd argue this subject with Temp. Religion, maybe, but not this.... |
|
| |
|
Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | Hermann Ludwig von Helmholtz...German MD and Fysicist...deceased 1894
--------------------------------------------------
P Templeman :
Also, I'm confused by the phrase "bass-cancellation occurs at lower freq. than an acoustic git. generates" What the hell does that mean?
from my previous post :
I have played my 1537 without it`s back-hatch ( keeping it well away ) , and there`s not that much difference in sound , not really louder , no higher clarity ,perhaps a little " muddy " ,without true loss of bass.
Understanding that this a guitar-site where I`m not with like-minded , I allways try to use simple wordings , if I was to discuss Electro-Acoustics , than I would go to appropriate places , ... baffling people with hollow phrases is of no interest to me.
Here , a little talk about everything , Guitars in particular , even a little discussion about amps. or speakers , Sure , but an in depth argument about electro-acoustics is out of place here , if you really want to pursue that subject , then you can find me at appropriate web-sites ,..
At the moment , I am in the process of building several soundsystems , incl. loudspeaker cabinets , many possibilities are being considered/scrutinized , amongst others ,TRUE triple bandpass systems , not three bass-reflex enclosures build on top of each other , no , three chambers looking into each other , incorporating calculations based on observations made by H L von Helmholtz , yes , the first time that I heard the name was fifty yrs. ago , ... I know several names pertaining to Electro-Acoustics , some of which I had the joy to work with , common for craftsmen is that , albeit they like to talk about the things they do , they do not argue , ... discuss yes , even heated debates , but always with the incentive to arrive at improvements , if you want scientific explanations , then why are you asking for that here ?.. , your comment about..:
P Templeman :
Just because the dimension of a guitar relate to certain frequencies does not mean that the frequencies in that range will be boosted. Stringed instruments follow Helmholtz principles and in most guitars the fundamental (or Helmholtz Frequency) of the air chamber is tuned to somewhere between F# and A (93Hz to 110Hz) way below the 650 to 3K range you allege.
That is a Discrepance in itself , where did you get that from ?... from a guitar manufacturer who claim that they ...
" take a tone and build a guitar around it " ..
I heard that one too ,together with like-minded , and we all had a good laugh.. for that would mean a HUGE resonance , without much else.
A Chamber WILL have it`s range based on it`s VOLUME , observed by H L von Helmholtz , where it works as an ACOUSTIC Amplifier .
Test :
When a string is suspended in FREE AIR at CERTAIN TENSION , only held in place by EITHER END , String will sound THIN and at LOW VOLUME , ..
FUNDAMENTAL FREQUENCY is RESONANCE of said String.
When said string is Suspended at Certain Tension , Coupled Physically at a small Area to a Plate ( Membrane ) and Coupled to a Chamber with an Opening in it , such as with a guitar , than VOLUME Increases at FUNDAMENTAL Frequency,
( many here know how loud that can be )
Several times have you mentioned that the Sound-Opening of a guitar is a Helmholtz resonator .
A Helmholtz Resonator is an ACOUSTIC RESONANCE DAMPER , by turning a certain Shallow frequency range in OPPOSITE PHASE , thereby CANCELLING said frequency.
However , when looked at the DIAMETER and PORT LENGTH of the Sound Opening of an Acoustic Guitar , we can see that it is not tuned to your proposed frequency tuning..
Sound-Opening of a guitar has a Diameter and a Port Length , which would be the Thickness of the Top-Plate.
Which in turn would mean , that when additional openings would be employed , the whole guitar would be out of it`s , what , Fundamental or Helmholtz frequency ? .. ,
Kind Sir , I had not heard about Helmholtz frequencies before , I have learned that it was expressed in Hertz , unit was named after Heinrich Hertz ( who was a pupil of Hermann von Helmholtz ) after having clarified ( proven ) , the Electromagnetic Theory of Light by J C Maxwell ...
( first proposed by Isaac Newton , the very same gentleman who lends his name to the Unit " Newton/meter " abbreviated to Nm )
The Hertz unit indicates an Oscillation with a certain Wave-Length at a certain Frequency.
However , a simple test that can be carried out by any one with access to an Ovation , model " ELITE " , by removing the Hatch at back-plate ,and playing said " ELITE " , would prove that it matters very little , if at all.
So there goes your theory.
No-One here needs to take my words for gospel , instead , find web-sites with calculations about Bass-Ducts for Bass-reflex systems , and see the Ratio ..Box Volume v s Duct Volume..
I could go on and on..but this is not the right place , ergo , further I will not go.
It is Five in the morning , I`ve spent most of the night decorating/readying the place for my youngest daughter`s Twenty-First birthday , and in a few hrs. , I`ll be cooking Belgian Gulash served with French fries , and I still have to buy her a present...
I need to get a little shut-eye..
....but first , a night-cap ...
Vic
Good Night. |
|
| |
|
Joined:
May 2008
Posts: 4996
Location: Phoenix AZ | Wow, somebody hijacked the presidential tele-prompter. Lots of words but mere mortals have no freaking idea what's he's saying.
Belgian Gulash 1, Helmholtz 0.
But Vic, I gotta 100% disagree with you on one thing. When I take the hatch door off the back of my guitar it's sound goes completely to shit. No volume, no bass, just awful. I have no idea what that means except that I'm not very motivated to go cutting extra sound ports in my guitar. Or to misplace the hatch door cover. |
|
| |
|
Joined:
December 2006
Posts: 6268
Location: Florida Central Gulf Coast | Originally posted by FlicKreno aka Solid Top:
When a string is suspended in FREE AIR at CERTAIN TENSION , only held in place by EITHER END , String will sound THIN and at LOW VOLUME , Vic, you are truly a fount of info...
But I gotta pick on ya a bit... 
How does one apply tension to a string held in place on only one end; other than gravity, which would essentially have no effect due to the minuscule difference in 'altitude' (delta psia) of the top and bottom of said string? 
Hey, have another adult beverage and a great time at the birthday party. BTW, are your French fries the same as pommes frites? |
|
| |
|
Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | Both ends... :)
Vic
..that nIffy.. ;) |
|
| |
|
Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | Hey, have another adult beverage and a great time at the birthday party. BTW, are your French fries the same as pommes frites?
----------------------
Thanks Iffy , I guess them pommes frites are maybe more potato-like.. :D
..it was like only yesterday that she tried to climb the pram , dressed in a little yellow skirt with matching yellow sweater..
Vic
..that was eighteen yrs. ago... |
|
| |
|
Joined:
February 2002
Posts: 5750
Location: Scotland | Belgian waffle, which had the clarity of very thick mud. I'm not going to waste me time on this any more, I have better things to do with my life. I'm saddned to know that everything I've ever learned about acoustic physics is wrong. I think I need to go back to campus and complain. |
|
| |
|
Joined:
December 2004
Posts: 581
Location: Denmark | The projection I mention is provided by the increased stiffness of the guitar body walls of the roundback compared to a flatback. This makes the roundbacks act more like a true Helmholz resonator. I am not a specialist in the field but it appears to me that the physics are not that far from the ported speaker enclosures.
Happy birthday, Vic's daugther :-)
 |
|
| |
Sound Ports