#1
I mentioned them in another thread, so I thought I would show you mine (sound port, that is):



I did this a few days ago in my Colombian requinto.

There have been assorted claims that it changes the tone as perceived by both the audience and the player. In my case it was intended purely for player benefit, on the premise that high frequencies don't go around corners as well as low ones. This guitar is a bit woolly sounding, so I thought that having some of the sound vented directly towards my right ear - I play seated with the guitar on my right knee - would help to brighten it up, from my POV as the player. I thought it only had a smal, albeit noticeable effect, but my mate at the music store, whose hearing is likely better than mine, thought that the effect was quite evident. Coincidentally, he had put a sound port in one of his guitars on the same day, I tried it and thought that the effect was more noticeable than on mine, form both the audience and player POV.

The point of all this is that if you have a clunky cheapo and a dremel, this might be worth a try. Mine was a bit tricky, because the sides are very thin solid timber and I currently don't have a dremel. Also, I put reinforcing strips inside, on the leading and trailing edges of the hole, and this was complicated because the soundhole is too small to get my hand in. I don't think that the reinforcing would be necessary on laminated sides.
#3
I have an accidental one on my stagg, it was an electro acoustic but the pickup was stuffed so I pulled all the electronics out and wired them into a friends electric bass. (works well but that's a story for another day) This has in essence given me a sound port in the upper bout. From a player perspective it is muddy overly bassy and very warbly. From audience perspective it seems brighter. Either way I now hate playing it so am making up some carbon covers because why the hell not.
#5
Is anything about sound ports written down anywhere?

I would swear the size f the hole is critical to the tuning frequency of the guitar.

I would further swear the hole should be in the upper bout, to let the high frequencies out.

(Hm, I'm a poet and didn't know it).

Not that this has anything to do with guitars but, if you design a bass reflex speaker enclosure, and the bass port is to small, it will whistle, (sort of).

I only mention this because of the size variance of pre-amp mounting holes. It seems like, (on average), they would be too small. Dunno if the odd shape is an issue or not.
#6
Quote by Captaincranky
Is anything about sound ports written down anywhere?

I would swear the size f the hole is critical to the tuning frequency of the guitar.

I would further swear the hole should be in the upper bout, to let the high frequencies out.

(Hm, I'm a poet and didn't know it).

Not that this has anything to do with guitars but, if you design a bass reflex speaker enclosure, and the bass port is to small, it will whistle, (sort of).

I only mention this because of the size variance of pre-amp mounting holes. It seems like, (on average), they would be too small. Dunno if the odd shape is an issue or not.


There are a variety of soundport location and configuration ideas out there (which I'm sure you're aware of.)

Kevin Ryan does a lot of lower bout, bevel soundports.

Whereas my guitar has an upper bout, single hole sound port:

My God, it's full of stars!
#7
Yes, sound port locations, sizes and shapes vary a lot. I discussed it with Alan Carruth on UMGF, and looked at some pics before I did it. Alan has done a fair bit of experimental work on them, and he didn't think that either size or specific location were that important, within reasonable limits, though he did say that further from the soundhole was better. I chose that location because it is aiming at my right ear, and Alan thought it was OK from the pic.
#8
^^^ No, the whole affair seemed so "spur of the moment", it took me quite by surprise...

Quote by Dreadnought
There are a variety of soundport location and configuration ideas out there (which I'm sure you're aware of.)
Well, heretofore, I had been thinking the bevel on the lower bout was intended to allow freer movement of your strumming arm. But, I suppose a row of holes blowing cooling air into your airpit, and also acting as a soundport, is a coup of multi-tasking.

Quote by Dreadnought
Whereas my guitar has an upper bout, single hole sound port:
Right where I had been thinking they should be all along...

I wunner if'n I blasted a hole in the side of either of my Ibanez acoustics, that would bring their sound up to its full potential?
#9
for me, sound ports add a lot more bass for the guitars we've added them to or that came with them, a big improvement for me, the player. never played a guitar with a sound port that sounded brighter, though.

most of the sound ports i've seen or that we cut were in the upper bout.
Quote by Skeet UK
I just looked in my Oxford English Dictionary and under "Acoustic Guitar", there was your Avatar and an email address!
#10
Yes Alan Carruth said that can alter the perception of bass, through a complicated bit of phyics. I think that the location would depend to some extent on what you are trying to achieve, and your playing position.

Coincidentally, my mate put one in the same place on one of his guitars on the same day.

I'll listen to mine again in a quiet environment and report back.

Now I'm thinking about adding another matching sound port in the upper bout. A sort of belt and braces exercise.

Here's one luthier who thinks that the lower bout location is good

http://www.edwinsonguitar.com/Design_Philosophy/Entries/2013/8/7_The_Sound_Port.html
#12
Quote by Dreadnought
Stephen Sheriff


we know him
Quote by Skeet UK
I just looked in my Oxford English Dictionary and under "Acoustic Guitar", there was your Avatar and an email address!
#15
OK. The problem guitarists have, which violinists don't, is we never actually hear the true sound of our instruments. Unless.......(wait for it).......you plug in and sit in front of the amp. (Yeah, I can hear the poop that going to start up, even before I post this).

However, the fact the sound port doesn't give you more "presence", seems sort of disappointing, as that's what you're missing sitting behind the guitar.

I will say however, I really think a 12 string might benefit from a sound port, more so than a six. This because twelves can be annoyingly bright while you're playing them. My normal approach is to plug in and EQ for low volume amplification, bass way up, treble rolled way off. If you saw my curves on an EQ with sliders, it would look like a ski jump, as opposed to what you normally see with both ends way up, and the cut in the mids.

I had been thinking, (albeit provably), that changing the size of the sound hole, (or adding area to it someplace else, would change the tuning frequency of any "enclosure".

Speaking of which, I think material matters as well. I'm going to use a terrible example, Ibanez acoustics.. (A groan came from the audience as soon as I said "Ibanez"). That said both my Ibanez are approximately the same "volume", yet the spruce laminate one has a huge sound hole, while the hardwood laminate clunker's is much smaller. Oh well, who knows if they even design for sound quality, so this might be a moot point.
#16
Helmoltz resonator - a hollow cavity whose resonance frequency increases as the size of the aperture increases. The "air resonance frequency" of an acoustic guitar increases as the soundhole or sound ports get bigger. I've experimented with making a soundhole smaller to try and get a darker sound out of my kona, using a lute hole:

https://c2.staticflickr.com/4/3761/11358083953_1f16ef5454.jpg

It just made it sound dull, so I ended up using three brass pins to moderate the treble response.

I'm not sure that a sound port would benefit a bright 12-string. You could try it and report back. I think a lute hole might be a better bet though.

I think that materials and overall construction will have more effect than soundhole size, with reasonable limits, as always.

For some reason image post isn't working.
#17
Quote by Tony Done
Helmoltz resonator - a hollow cavity whose resonance frequency increases as the size of the aperture increases. The "air resonance frequency" of an acoustic guitar increases as the soundhole or sound ports get bigger. I've experimented with making a soundhole smaller to try and get a darker sound out of my kona, using a lute hole:

https://c2.staticflickr.com/4/3761/11358083953_1f16ef5454.jpg

It just made it sound dull, so I ended up using three brass pins to moderate the treble response.

I'm not sure that a sound port would benefit a bright 12-string. You could try it and report back. I think a lute hole might be a better bet though.

I think that materials and overall construction will have more effect than soundhole size, with reasonable limits, as always.

For some reason image post isn't working.



OK, if you're using Flickr as a photo source, there are some steps you need to take to permit the image to a be accessible via a link. Try googling that as a topic. (I read about it once, then forgot every word).

And no, I'm not going to cut a hole in my Taylor 12 string. Can you say, "amplifier"? Sure you can...
#19
Quote by Tony Done
I didn't have a problem with Flickr until today. There's no image icon visible.
No, you have to use the "go advanced" button, in the upper right hnd corner of the postbox, before you get emoticons or hyperlink and image insert functions.

Basically, the "post reply box," has become a substitute for the, "post quick reply box".
#21
Quote by Tony Done
??????????


You two have thoroughly confused me
My God, it's full of stars!
#25
Now violins were mentioned and that got me thinking (it's dangerous when I think).
Violins (or atleast the ones I've seen and made screechy noises with) have a tone rod that is 'wedged' between the top and the back. I don't know but I assume this is to transfer the vibrations from the top to the back to increase the amount of air moved/or the amount the air is moved (probably wrong about that should probably Google this first) would something like this give a guitar more volume and give the player a better sense of the 'true' sound of the guitar given that it is moving the air directly in front of the player?

Will also add that I've had a few ales so I may be chatting bollocks.
#26
I think you're right about violins, but I don't think it would work on a normal guitar because of damping caused by body contact on the back. However, gibson (Lloyd Loar?) experimented with a design of that type for guitars; they had a deep rim to stop the back touching the body.
#27
Quote by Thom1989
Now violins were mentioned and that got me thinking (it's dangerous when I think).
Violins (or atleast the ones I've seen and made screechy noises with) have a tone rod that is 'wedged' between the top and the back. I don't know but I assume this is to transfer the vibrations from the top to the back to increase the amount of air moved/or the amount the air is moved (probably wrong about that should probably Google this first) would something like this give a guitar more volume and give the player a better sense of the 'true' sound of the guitar given that it is moving the air directly in front of the player?

Will also add that I've had a few ales so I may be chatting bollocks.
No matter what the "tone rod" does, a violin is played at ear level. As it's under your chin, it's also slightly below ear level, and the sound comes out of the "F" holes.

We actually had a thread about this topic, which unfortunately may not have gotten as much airplay as it deserved. IIRC, the title was, "do you ever play your guitar, while sitting facing into a corner". Under that condition, you ears are, "closer to the scene of the accident", so to speak, and you do get the forward only moving sound "high frequencies", reflected back at you.

I'm not convinced that, "sound ports", aren't a current fashion, or at least partly so. As has been said, they don't help with the highs, and hence the presence of your instrument, hence, I'm not entirely convinced me of their necessity.

I quite honestly think a clean, (very low noise floor), PA system, is a better solution. Even when you don't turn up. Human hearing has different sensitivity to different frequencies at different volumes. All you need to do, is twist the dials, or slide the sliders on an EQ, and hear what you want to hear.

Annnnd...., this will probably start an argument about whether or not any pickup faithfully reproduces the sound of an acoustic.

My vote goes for, "who cares". The vacuum tube and audio amplifiers were both invented before I was born. Hence, I've never lived without them, and have never been exposed to music that was created without electronic intervention.
#28
I copied this from AGF, I hope Alan doesn't mind, but his opinion is one I trust more than most:

Alan Carruth
12-28-2013, 01:43 PM
The corker was my first experiment with sound ports: I've made two more 'test mules' since to get more data, and also built a number of ported guitars at customer request.

A sound port is not magic. It does what it does. If that's something you want or need, it will be useful, if not, then it won't. The 'corker' was built to start to figure that out, and the other two mules were used to answer more limited questions.

Trying to keep this brief:

Since the wave length of the lowest notes on the guitar are much longer than the box, guitars radiate lows more or less uniformly in all directions. Once you get above the pitch of, say, the open G string, they become more directional, with most of the highs going out of the hole and off the top toward the audience. In general, the player hears those high frequencies mostly from reflections from the room. In a large, 'dead', or noisy room, you don't get that high frequency feedback. I can attest to how hard it can be to play a guitar in that circumstance!

A port that the player can see will direct some of the high frequency energy from the box toward them. This raises the sound level at the player's ear (as Tim found), and increases the 'articulation' of the sound they hear.

Opening a port does increase the output at certain pitches, sometimes by a lot. The 'main air' mode can be 3-7 dB louder with an open port, depending on the location. This may not be as obvious as you might think: doubling the power (+3dB) usually yields a just noticeably louder sound. Also, the increase is over a very narrow frequency band: just at the resonant pitch.

Any internal resonance the port 'hears' will be raised in pitch. The 'main air' pitch usually rises by a semitone or so, and the more the power increase the greater the pitch change. This may or may not be heard as a change in timbre, depending on how the pitch change relates to played notes or overtones.

There can be other changes in timbre, depending on the exact line up of things on a particular guitar.

In the end, the biggest benefit of a port seems to be it's use as a monitor for the player in 'dead' or noisy rooms. A blind test of players in small and 'live' rooms showed that they can't reliably hear the difference, but a similar test I ran at two Montreal shows, a folk festival and a GAL convention, showed that players hear the difference clearly in noisy spaces. I'd expect a similar benefit in a 'dead' room or, say, outdoors.

If there is a benefit to the audience it's more limited: in properly conducted 'blind' tests of audience response the results are not nearly as clear as the player tests. I think a lot of the remarkable results that people have gotten in audience tests have had to do with the placebo effect. People expect to hear a change, and they hear it.


This is more or less the premise I was working on, as mentioned at the start of the thread - a sound port can increase the player's perception of high frequencies. Though he does point out that it might not be evident in an audio-reflective environment. None of my argument is about what effect it might have on the "audience tone" of the guitar, and I thing this is where there could be some confusion of our (used generically) opinions of sound ports.

Note that I was having the opposite problem with the lap steel, because it faces upwards, it was too bright up close and personal to the player. If you are playing amplified, then the sound reinforcement system will fix and problems, as you say.
#31
Quote by Tony Done
I copied this from AGF, I hope Alan doesn't mind, but his opinion is one I trust more than most:

Alan Carruth
12-28-2013, 01:43 PM
The corker was my first experiment with sound ports: I've made two more 'test mules' since to get more data, and also built a number of ported guitars at customer request. ...[ ]....
What I get from Mr. Carruth's "brevity" is this.

The sound port is unlikely have a great overall effect on the "quality" of the instrument.

It can increase your satisfaction with the instrument, simply by virtue of enabling you to hear more of what it's doing.

From the standpoint of live performance, the utility of the sound port is limited in scope to a specific type of venue parameters.

Accordingly, today's musicians are using in ear monitors to do the job of either floor monitors, huge amp stacks, and quite possibly sound ports as well. One has to assume doing it better as well, as all of what's going on can be ported to the earpiece, not just a specific segment of a guitar's range.

Addressing the herd which is AGF, if one builder does a guitar with a sound port, and the buyer loves it, the rest of the pack will be asking for sound posts as well. One has to assume that would put pressure on other builders to follow suit and include the ports on their new builds When you have a bunch of people screaming, "I want one too", you have to label at least part of the mystique as it "being en vogue,"a trend", "current fashion", or what have you.

Not that that is entirely a bad thing. Acoustic guitars can be pretty damned boring looking after the first few hunnerd years or so.

One truly paradoxical part of this is, it reverses Ovation's sales pitch that, "because of our parabolic bowls, sound isn't wasted getting lost in the guitar, or going out the back, it all comes out the sound hole, the way it's supposed to".
#33
Quote by Tony Done
...[ ]...I'm only interested in them from the non-amplified player's POV, ie a back porch picker, I'm skeptical about their audience benefits.
Which it seems, is actually where they might do you the most good. Unless you do your "porch pickin'" facing the house, you got nuttin' coming back at you in the way of reflected sound.
#34
Update.

This is one I did one my Maton, replacing the preamp. I now it isn't very elegant, but it's better than the big rough hole.

I replaced the strings at the same time, so I'm not sure how much effect it has had. However my daughter remarked on how loud it sounded when she tried playing it.

#35
Quote by Tony Done
Update.

This is one I did one my Maton, replacing the preamp. I now it isn't very elegant, but it's better than the big rough hole.
Well, it looks fine to me. Realistically, the only thing I can imagine which would refine it, would be try and duplicate the rosette inlay. Which isn't in my wheelhouse, and sounds like a major PiTA, even for someone who can.

Quote by Tony Done
I replaced the strings at the same time, so I'm not sure how much effect it has had. However my daughter remarked on how loud it sounded when she tried playing it....[ ]...
I'm starting to think these sound holes are surreptitiously pandering to players vanities as much as anything else. "Now that I can finally hear myself, my god I'm good"!. (Well, at least that's what I'd be thinking.. ).
Last edited by Captaincranky at Jun 26, 2016,
#36
This morning I converted the three holes to a simple rounded triangle. I think it is a bit better, but not a lot. I agree that something like a rosette or maybe a lutehole would be the go, but that's well outside my capabilities. If I had a dremel (mine bust a few weeks ago and I'm trying to get a warranty replacement) I would try something a bit more ambitious. If I really get fired up, I might try to locate a local fret sawyer, I think that one of those old guys would like a project like this.

Vanity? Nah, good tones make you try harder. I'm just now revisiting Jansch's "Blackwaterside" it sounds fantastic on this guitar, or would if a could play it half decently. I think what the sound port is doing mostly is making the attack sound sharper. less wooliness, not really so much about pitch or volume.

I think that my daughter's perceptions are more about the new strings - EB aluminium bronze - than the sound port. Well worth a try if you like loud and brash.
#37
Next iteration.

I decided to have yet another go at it:



This version includes passive tone and volume controls for the soundhole pickup, I'll put nicer knobs on it when I can find some. I took it to show my mate at the music store. He was impressed enough to be wondering how he could include a combined sound port and piezo preamp control in his importer line of guitars.
Last edited by Tony Done at Jul 2, 2016,
#38
Been checking in on this thread from time to time. As said initially, didn't like what my 'sound hole' did to my stagg.
Gotta say though Tony, you seem like someone I'd get in with due to what seems to be a 'im'a try this, im'a try that' approach.

Sorry about the 2 previous posts. They were duplicates, tried attaching a file but it said it was the wrong type but seemed to post the rest anyway.
Last edited by Thom1989 at Jul 5, 2016,
#39
Long ago I used a stethoscope on my guitars, the sound right out of the wood, of course, was incredible, the best a guitar has to offer Different locations produced various timber and brightness ranges. This method might be used to determine where you want to place an additional hole, whether to increase or decrease brightness for your listening pleasure.
You could draw on a design and use a dremel to cut out the pattern - just to be artistic and not have a gaping "hole". You could just as well add a removable "rosette" insert to the hole.
I percieve the only purpose to be for the player's ears though some frequencies will be conversely adjusted at the main sound hole to an audience.
#40
skido13

My dremel isn't working at the moment, which is why I kept it simple, but I had considered fancier designs and "lute hole" covers. I discussed the location with Alan Carruth on UMGF, and he thought it was OK. - My intention was to alter the player's perception of tone rather than that of the audience. However I took the Mation down to my mate's store, and I could hear a difference when he was playing it with the sount port covered or uncovered. From the player's POV, I think it "hardens" the attack rather than shifting the pitch, but hard to tell with new strings.

The stethoscope idea is interesting, but I'm not sue that the timber tones would help find the best air tone location. If you're interested Al Carruth has done some fairly systematic work on sound ports. I get the impression he isn't wildly enthusiastic about them, but is happy to include them if the customer requests.