So, I would like to build a simple, or not so simple damp ducted voigt pipe speaker enclosure. Good combination of uncomplicated design, and hopefully good sound.
Now my question. For given design, say one done for a specific speaker, fostex xyz for hypothetical example. How much flexability is there in substituting different drivers? I have no desire to become a speaker design expert, but what are the critical speaker parameters that go 8nto the design of a voight pipe etc.?
I would like to start out with a modest driver, with the hope that an upgrade would be possible that would work with the original design.
Most of the folded horn orvoight pipe info articles go into way more detail than I am willing to invest in at this time. General, overview types of web sites or articles are not readily found.
Roger
Now my question. For given design, say one done for a specific speaker, fostex xyz for hypothetical example. How much flexability is there in substituting different drivers? I have no desire to become a speaker design expert, but what are the critical speaker parameters that go 8nto the design of a voight pipe etc.?
I would like to start out with a modest driver, with the hope that an upgrade would be possible that would work with the original design.
Most of the folded horn orvoight pipe info articles go into way more detail than I am willing to invest in at this time. General, overview types of web sites or articles are not readily found.
Roger
Last edited by a moderator:
Basically its a plain old vented enclosure.
With a port that is too big and too long.
or just too long
Otherwise transmission line
and million other names to argue about.
So be better off using a actual more modern
well designed transmission line.
Which would tame the expected extra port resonance
from making ports too long.
Vented enclosure is vented enclosure.
More bass just comes from suitable drivers.
Something with a resonant frequency
way below 60 or 50 or 40 Hz
You know a woofer around 30 to 20 Hz ish
otherwise same old high tuned port that is too
long. And a million names to call it.
Not wanting to go down the rabbit hole of enclosure design
sounds good to me.
Make a tower, vent it close to the woofer instead of the bottom.
call it a voigt or any other name you wanna make up.
Or vent at the bottom which in a tower will behave more like a transmission line.
So a huge rabbit hole of theory to get rid of extra resonance
and magic theory to work out more error factors really.
With a port that is too big and too long.
or just too long
Otherwise transmission line
and million other names to argue about.
So be better off using a actual more modern
well designed transmission line.
Which would tame the expected extra port resonance
from making ports too long.
Vented enclosure is vented enclosure.
More bass just comes from suitable drivers.
Something with a resonant frequency
way below 60 or 50 or 40 Hz
You know a woofer around 30 to 20 Hz ish
otherwise same old high tuned port that is too
long. And a million names to call it.
Not wanting to go down the rabbit hole of enclosure design
sounds good to me.
Make a tower, vent it close to the woofer instead of the bottom.
call it a voigt or any other name you wanna make up.
Or vent at the bottom which in a tower will behave more like a transmission line.
So a huge rabbit hole of theory to get rid of extra resonance
and magic theory to work out more error factors really.
Last edited:
At the risk of introducing some basic physical principles, you'll potentially get some joyous resonant issues if you simply 'make a tower, vent it close to the woofer instead of the bottom'.
For example, attached. The upper is a reasonably well-designed 'vented tower' alignment intended for use in a moderately large space & for critically damping via the old click test to suit the room acoustic. The lower is the exact same speaker with the vent moved to close proximity to the driver, no other changes. QED. The problem with over-simplifying everything to the description of a 'plain old vented enclosure' & assuming that only Helmholtz action exists is that ye olde laws of nature don't make it so.
A Voigt pipe unfortunately is not a 'plain old vented enclosure' and doesn't actually work on those physical principles, as its resonant behaviour is primarly dominated by eigenmodes (standing waves) rather Helmholtz (cavity resonance) so claims to the contrary are unfortunately mistaken.
Back to the actual question: short version re how much flexibility between different drivers is 'it depends'. A longer version is 'if the enclosure is acoustically large and Vb / Vp (pipe volume) swamps Vas then there is a modest amount of flexibility, as would also be the case with a conventional vented box, although the alignment will vary depending on how significantly the driver Fs, Vas, Qts differ from each other. Providing there isn't a huge variation, the differences also shouldn't be huge as far as the alignment is concerned (anything higher up is a different matter mostly unrelated to the box). Most drivers are built to a moderate production +/- QC tolerance anyway. The greater the deviation in spec. between the units however, the greater the difference you can expect to see in alignment terms. As noted above, for a Voigt pipe (aka ML-horn, aka [single] tapped horn, aka TQWT etc.), like any other enclosure, the dominant lumped driver parameters as far as alignment is concerned are Fs, Vas & [effective] Qts once amplifier output impedance or any series R from speaker wire & connectors are factored in.
Top tip: build a well-known, proven design from somebody who knows what they're doing. Ed's Vofo above is a good example.
For example, attached. The upper is a reasonably well-designed 'vented tower' alignment intended for use in a moderately large space & for critically damping via the old click test to suit the room acoustic. The lower is the exact same speaker with the vent moved to close proximity to the driver, no other changes. QED. The problem with over-simplifying everything to the description of a 'plain old vented enclosure' & assuming that only Helmholtz action exists is that ye olde laws of nature don't make it so.
A Voigt pipe unfortunately is not a 'plain old vented enclosure' and doesn't actually work on those physical principles, as its resonant behaviour is primarly dominated by eigenmodes (standing waves) rather Helmholtz (cavity resonance) so claims to the contrary are unfortunately mistaken.Back to the actual question: short version re how much flexibility between different drivers is 'it depends'. A longer version is 'if the enclosure is acoustically large and Vb / Vp (pipe volume) swamps Vas then there is a modest amount of flexibility, as would also be the case with a conventional vented box, although the alignment will vary depending on how significantly the driver Fs, Vas, Qts differ from each other. Providing there isn't a huge variation, the differences also shouldn't be huge as far as the alignment is concerned (anything higher up is a different matter mostly unrelated to the box). Most drivers are built to a moderate production +/- QC tolerance anyway. The greater the deviation in spec. between the units however, the greater the difference you can expect to see in alignment terms. As noted above, for a Voigt pipe (aka ML-horn, aka [single] tapped horn, aka TQWT etc.), like any other enclosure, the dominant lumped driver parameters as far as alignment is concerned are Fs, Vas & [effective] Qts once amplifier output impedance or any series R from speaker wire & connectors are factored in.
Top tip: build a well-known, proven design from somebody who knows what they're doing. Ed's Vofo above is a good example.
Last edited by a moderator:
More accurately called an ML-Voigt.
An example (the FE108e∑ Scott & i did for a client). We also did one for FF165wk.
While each box should be designed for the speaker driver used, the box does dominate so there is some leeway. Nandape takes advantage of that with his ML-Voigts.
BTW: damped duct is a mis-nomer. The duct ia not damped., the duct (more accurately restricted terminus) provides mass[-loading and an additional and signioficant low pass filter for the output of the terminus. Really a must in a Voigt to help kil the LF ripple.
dave
Balderdash.
A Voigt has a quarterwave resonance that a BR very much does not,.
dave
Roger, if you’re looking for a simple construction that can deliver decent performance with currently available affordable drivers, you could do far worse than any of numerous enclosures by Scott Lindgren. They range from extremely simple builds like the Pensil family to rather elaborate manifold Olson labyrinth types, of which I’ve constructed more than a few. I’m retired from active building for almost 6 years now, but continue to be very happy with a pair of Pensils for Alpair 10.3, which while now out of production does have current descendants.
Keep in mind that meticulous designs tend to be optimized for the T/S parameters of specific drivers, often using more elaborate techniques than most simple online formulas allow for.
Keep in mind that meticulous designs tend to be optimized for the T/S parameters of specific drivers, often using more elaborate techniques than most simple online formulas allow for.