I made a pair of Voigt pipes and

I was using them with a pair of Fostex Sigma 208s. The sound was fast, but a tad lean. I later found out that the Voigt cabinets themselves, because of their narrow fronts, tend to eliminate some lower frequency extension of any fullrange driver used. This was something I found out while writing back and forth with TWL, another member who has a Voigt pipe with Lowther EX-3 or 4 drivers. He found a way of remediating this.

Before you go to his thread, I think I understand why the speaker and its narrow front baffle eliminated some lower frequency. If you think of the fullrange driver as the beginning of a ripple, in order for it to expand exponentially, you will need a large area. Think the image of a pond. Nevertheless, because the Voigt pipes are narrow, as the sound waves propagate, their ripples tend to become cut off, expecially towards the sides of the cabinet, I think this is what causes the loss of lower frequencies.

Tom Lyons, AKA:TWL, came out with an ingenious solution. He added "wings" to the sides of his cabinets, if the front was 12", he added 12" wings to each side, that are hinged with some piano hinges. They can be in a plane with the front baffle or angled backwards, depending of the effect that was needed. For what it seems to be, his system must sound glorious.

I myself, cannibalized the Voigt pipes and have placed the Fostex in a folded horn cabinet, a Zhorn that Tom Zuworsky made for me...because I wanted some lows. On top of that, I added a powered subwoofer for even a more pronounced lower end.

I am happy with the sound I get now.

The Voigt pipes, with the winged mods should not be hard to make. It took me about a day to get the pieces cut. You need some room to manouver the sides and the front...if you have the space and one helper, I think you can make them for about $450, with ply and drivers included. They do sound dynamic, better than a 3.5 K commercial pair of speakers that I still have around.

PS: With the winged mods, I am sure that the Voigts will sound explosive by themselves.
Peoples adding "WINGS" to their Altec A5 speakers for a long long time....

Narrow baffles typically aid in imaging and dispersion at higher frequencies. Taking such an approach can hurt bass response though AND it can also play havoc with higher frequencies too. That is, IF the speakers are placed close to the wall behind them and / or are of a bipolar design.

In either case, the time & distance between the front wave that is in phase and the rear wave ( dipolar radiation OR reflections from the wall behind the speaker ), which is out of phase, can cause major "rippling" due to cancellation at many different frequencies. By making the return path of the reflection longer by adding width to the baffle, you minimize these problems. This also increases the time & distance between the rear out of phase signal of a dipole and the in-phase front wave, offering the same benefits.

Rather than minimize baffle area on his designs, which can improve imaging but allow the above mentioned problems to come into play, Arnie Nudell used stationary "wings" or extended baffles on his big Infinity and Genesis designs. Problem with increasing baffle size at higher frequencies is that you can also run into diffraction problems. Arnie took care of that by radiusing the baffles i.e. gradually sloping them backwards in a gentle bend. In effect, the radiation pattern of the speaker is not drastically effected, even though it has a larger baffle, and the rear wave reflections / cancellation problems are drastically reduced.

Another way to get around this is to control the dispersion of the speaker. By manipulating the radiation pattern through baffle shape and size AND applying acoustic treatments to the baffle, you achieve much the same effect as that above without the larger surface area of the "wings" or radiused baffle extensions. This makes it harder for the sound to "bend around" the baffle due to being aimed in one direction. The signal that does try to bend around is absorbed by the acoustic treatments. This design approach can be found in old AR ( Acoustic Research ) designs utilizing their "Acoustic Blanket" technology and in many of the Dunlavy designs. Ken Kantor, who was previously employed by AR and later helped design some of the NHT products, also took these factors into consideration on some of their models too.

These are two vastly different approaches that achieve very similar results in real world listening environments. It is this type of thinking / design engineering that separates "good" products from the typical "slapped together" products that most manufacturers foist upon the public. Sean

PS... One can "typically" gain some benefits similar to those mentioned above by surrounding the midrange / tweeter drivers with foam or felt. Varying the density, height and area covered are ways to fine tune just what frequencies are affected and the desired level of off-axis attenuation. The end results of such treatment typically result in a much smoother sound with improved imaging. You might have even seen the ads for AIM "Imagers", which are nothing more than foam rings that attach to the baffle around your tweeters. As mentioned though, this type of approach works FAR more effectively on the upper mids and treble. To get the benefits at lower frequencies, there is now way around increasing the baffle area via baffle extensions aka "wings".
speaking of wings.. http://www.tweakstore.com/index.html.
Interesting post Sean.
Viggen: Pretty interesting stuff. For those that want to check it out and are lazy, here ya go : )


Cdc: Did i "do good" on this one? I actually presented usable information with a technical explanation while praising multiple manufacturers. I did all of this without clobbering any other manufacturers or products in specific. Sean
Hey Sean, I thought that was great! I've read pieces of what you explained here and there over the years but you tied a lot of info together nicely, and I appreciated how you pointed out parallel (or almost) effects of some differing methods. Maybe old hat for some, but for this enthusiastic tweaker/non-engineer it hit the spot.
Sean, was that your website or someone else's? It was very nicely done. What I would like to see are some specific diagrams for easy making of the main speaker enclosure. I have been also attracted to the Jordan drivers, mainly because of the cost, but their sensitivity is mediocre and might need more than some SET amp can provide, beyond horn territory. Nevertheless, I am interested to see what the enclosure construction entails.

Shirasagi: I do what i can and am glad that this helped your understanding a bit. As i've mentioned before, if you really want to learn, you've got to do it yourself. I'd be glad to recommend some books if you're really interested. Personal experimentation with stuff like this also helps : )

Bemopti: I had nothing to do with that website. I know just enough about computers to annoy the hell out of you folks, let alone try to figure out how to put up a website like that. I simply reposted the same link that Viggen had provided, but did so in "clickable" form. I agree that it was a nice site / good "find" on Viggen's part and wanted to encourage others to visit it to see what we were talking about here. Viggen's "legwork" provided some great visualization aids to this thread.

With that in mind, this specific set looks beautiful. Don't know how well they work, but they look nice : )

Why not try emailing the guy that has the website? With all of the work that he's put into this project, i'm sure that he'd like to hear from someone that finds it interesting.

One thing that i would add is that you can use lightweight materials to form the wings ( easier to bend / conform to shape ) and then damp / brace them as needed. Starting off with something thin and easy to work with and then applying layers of other materials once you've achieved the shapes that you want would probably provide the easiest and least resonant path possible.

Believe it or not, "paneling" can be great for something like this. It is both cheap and easily bent. On top of that, if you can get the type with staggered width vertical lines cut into it, this can help break up standing waves along the surface of the baffle / wing. This can smooth the response even further. Sean

PS... The longer that you make the "wings", the more effective they are at lower frequencies. Shorter "wings" work best at higher frequencies and would be best suited for upper midrange and tweeter arrays.
Sean, regardless, the website is very well done. Just wish that it had some specific plans and measurements for the main cabinet. The wings, I am able to get the concept upright now.

Sean, I think you're ready for the big time. I vote to kick out Sam Tellig and have "Sean's Space" instead.
I would think adding wings would make a speaker sound more boxy. Maybe I'm wrong and have a lot of conflicting listening experiences but the Revel F30, with a wide front baffle, sounded very boxy. B&W Nautilus doesn't but maybe that's due to the curved cabinet as much as the narrow front baffle.
But then again Audio Physic Virgo's are so hung up on a narrow front baffle they are willing to put the woofers on the side which seems like a very BAD idea to me. Maybe it's for looks more than sound?
DynAudio Contour (?) 2-way monitors sounded incredibly boxy IMO. OTOH I had Ascend Acoustics CBM-170 which has a wide front baffle and I just could not hear any (or any significant) difference between them and my "tweeter on top" Nautilus 804. But then again, the Nautilus is nice because the tweeter on top makes a smaller cabinet which looks nicer and resonates less.
The most interesting demonstration of reducing boxiness was at the Paradigm dealer. He went up the line from Atoms to Titus (?) etc and each notch up the sound became more open and spacious. Despite the Atoms being the smallest speaker of the bunch.
Then again B&W claims the "drivers hung in space" design is the ultimate design. What Hi-Fi? said the floorstanding B&W CDM-7 came closest to the sound of their CDM-1 standmount than any other mfg'r floorstander vs. standmount. They said they added range way more than compensated for the slight resonance from the larger cabinet and that it was very rare for a floorstanding speaker to be able to do this. Something to do with cabinet design they said.
A local dealer actually had a speaker guy from CA stop by with his 3 way consisting of drivers mounted in those white plastic tubes you can get from Home Depot. The tubes were located but some type of wire framework. I guess they sounded really good. But $5,000 for 3 drivers and some plastic tubing? Whoa, I don't think so.
So if you want to approach a confusing issue, at least to me, what makes a speaker sound boxy? I don't think the baffle width or cabinet size has the effect that some mfg'rs like Audio Physic would lead us to believe.
Cdc sez:
what makes a speaker sound boxy
Usually a resonant peak @ 250-300Hz. The wood resonates giving a "honky" hue to the sound.

Virgo- I respectfully disagree that putting the woof on the side is that bad an idea. What Joacheim is doing is keeping the front baffle narrow (to help imaging) and, for low frequencies that CANNOT be easily located by our ears (i.e. there's no imaging), he uses the side baffle that is WIDER, placing the woof close to the floor (i.e. reducing baffle-step loss AND hoping for some floor boost).

Whether we like the result, is another matter:), but it makes sense!
Sure, if the Virgo's woofers cross over at about 30hz. But I doubt they do. Stereophile said in their 1995 Virgo review:
"So it's probable that the peakiness between 200hz and 300hz is due to some kind of internal standing wave phenonmenon."
Maybe your theory is true but the Virgo's did not sound boxy to me.
I would like to compare Virgo side by side with Nautilus 802 and hear if their is any difference between side vs. front mount. I like both speakers but side by side comparison would be best way to detect differences.
Side mounting a woofer should be done ONLY if the crossover point is quite low and the crossover slope is relatively steep. If such an approach is taken, bass distortion becomes less apparent and the benefits of a narrower baffle can be taken advantage of. Having said that, higher crossover points with shallower slopes will introduce more problems than they will solve with a design like this.

As a side note, i've seen quite a few designs using side-firing woofers that are mounted quite high in the cabinet. This in itself creates multiple problems and should be avoided. One of the biggest and most noticeable problems with such a design has to do with speaker placement & obtaining smooth frequency response / even tonal balance. Placement becomes much easier with such a design as the woofer is kept closer to the floor. Then again, if the woofer isn't really just a woofer and is being used to reproduce the lower midrange or above, mounting the woofer closer to the floor will introduce further problems. Such a design is a major compromise and should be avoided.

There are MANY factors to look at when designing a speaker. Those interested in building / buying speakers that actually work with room acoustics rather than fight them should do some reading about the Allison Effect ( named after Roy Allison ). The research that Roy and several others did back in the late 60's / early 70's is very interesting and worthwhile reading. Sean