Something wicked this way comes... (2020 speaker teaser content)

[ddk]

Very interesting! I had never seen anything quite like it before, the closest being the "vanes" in something like the TAD TH-4001, which (if I understand correctly) are there to manage the horn's cross-sectional area so that the expansion rate is exponential. But maybe they do other things (such as help with high frequency dispersion) as well.

My impression of Bill Woods, horn designer for Oswalds Mill, is that he's a very smart guy with a lot of tricks up his sleeve. I bet he has found work-arounds for any audibly significant issues, and I bet that little speaker sounds magnificent.

But he's not the ONLY guy doing a small speaker with a round (though not "conical") wooden horn!

Here's a 4 way 70's studio speaker with phase plugs on the woofers, they used them on woofers for a couple reasons I believe in this case it was to minimize higher frequency interference when the drivers are close as is the listening distance.



There are also dome type plug/lens that were common place in home audio.



and lets not forget good old pa speakers with phase plugs !



david

 

[Folsom]

I doubt the 70’s monitors have anything to do with being a phase plug. You can see their FR on the box. They might be excursion limiters, but that is hard to believe. Maybe simply weird grills.

 

[ddk]

I doubt the 70’s monitors have anything to do with being a phase plug. You can see their FR on the box. They might be excursion limiters, but that is hard to believe. Maybe simply weird grills.

I have those speakers they're not excursion limiters or simple decorative covers. Siemens used similar type round lenses on their full range theater speakers. Phase plugs are very common here's vintage Onkyo speakers.

 

[DaveC]

Actually, every single driver in my speaker uses a phase plug...

In compression drivers like the tweeter below they also serve to narrow the throat, in the dynamic drivers they prevent high frequency interference, it sounds a little weird without them.

 

[ddk]

Actually, every single driver in my speaker uses a phase plug...

In compression drivers like the tweeter below they also serve to narrow the throat, in the dynamic drivers they prevent high frequency interference, it sounds a little weird without them.

They’re everywhere!

 

[DaveC]

This is a recent Paradigm speaker with a "phase plug", maybe lens is a better term...

 

[DaveC]

They’re everywhere!

Hard to go back to dust caps once you've tried a phase plug.

 

[Folsom]

I have those speakers they're not excursion limiters or simple decorative covers. Siemens used similar type round lenses on their full range theater speakers. Phase plugs are very common here's vintage Onkyo speakers.

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Your other examples make sense because they apply to the mid band and they are larger.

In those cases they can even out power response. In the first case I sincerely doubt they could do anything at all unless the speakers naturally ring at s high frequency that is a harmonic of everything else played - even then makes little sense.

 

[morricab]

Very interesting! I had never seen anything quite like it before, the closest being the "vanes" in something like the TAD TH-4001, which (if I understand correctly) are there to manage the horn's cross-sectional area so that the expansion rate is exponential. But maybe they do other things (such as help with high frequency dispersion) as well.

My impression of Bill Woods, horn designer for Oswalds Mill, is that he's a very smart guy with a lot of tricks up his sleeve. I bet he has found work-arounds for any audibly significant issues, and I bet that little speaker sounds magnificent.

But he's not the ONLY guy doing a small speaker with a round (though not "conical") wooden horn!

View attachment 67695

Odeon Orfeo was another small speaker with a wooden horn.

 

[Solypsa]

...My impression of Bill Woods, horn designer for Oswalds Mill, is that he's a very smart guy with a lot of tricks up his sleeve...

Some years ago Bill did a design for me for a 15" coax diy project (which -sigh- is still in the to-do pile) and he is such a nice guy. He said that it took him 30 years to figure out how to make the seemingly simple design such as the one I got Haven't seen him online in years hope he is doing well...

 

[Audiophile Bill]

Odeon Orfeo was another small speaker with a wooden horn.

I don’t get the excitement about the marketing claim about a “small” wooden horn. A small wood horn is fairly easy to make if you know what you are doing.

Conical wood horns are the easiest horn of all to construct. Really a very simple process as long as you know what you are doing with a track-saw and it is accurate.

 

[morricab]

I don’t get the excitement about the marketing claim about a “small” wooden horn. A small wood horn is fairly easy to make if you know what you are doing.

Conical wood horns are the easiest horn of all to construct. Really a very simple process as long as you know what you are doing with a track-saw and it is accurate.

Well, I think the profile is Tractrix or Spherical, not conical on the Odeon speaker. I know that it was a lively sounding speaker with great focus and imaging. I really enjoyed it other than lack of deep bass, which ultimately wasn't so important. It mated very well with the KR Audio VA350i that I had at the time.

 

[Duke LeJeune]

Odeon Orfeo was another small speaker with a wooden horn.

BEAUTIFUL little speaker! (And I bet it sounds beautiful as well.)

I don’t get the excitement about the marketing claim about a “small” wooden horn. A small wood horn is fairly easy to make if you know what you are doing.

It's not the size that matters, it's how you... um... nevermind.

Seriously, imo a horn should be designed with the rest of the loudspeaker in mind, and if "the rest of the loudspeaker" is a 6.5" midwoofer, as with the Odeon Orfeo, then imo a matching horn makes sense.

Whether that's exciting or not probably depends on whether you have the option of using a much bigger speaker with a much bigger horn or horns. [Glances as Audiophile Bill's avatar and sees where he's coming from]

Conical wood horns are the easiest horn of all to construct. Really a very simple process as long as you know what you are doing with a track-saw and it is accurate.

Mine are oblate spheroids, which have a very precise curve of constantly-changing radius, so they are turned on a lathe. Most of the curvature is within an inch of the throat, not counting the round-over at the mouth. How many loudspeakers with oblate spheroid waveguides are on the market, wooden or otherwise, large or small? If there are others besides Earl Geddes and myself, I am unaware of them.

Of course any "excitement" I might hope this to generate is based on the presumption that the oblate spheroid profile has worthwhile advantages over others. Realistically that's probably a tough sell because they are so uncommon.

 

[Audiophile Bill]

BEAUTIFUL little speaker! (And I bet it sounds beautiful as well.)



It's not the size that matters, it's how you... um... nevermind.

Seriously, imo a horn should be designed with the rest of the loudspeaker in mind, and if "the rest of the loudspeaker" is a 6.5" midwoofer, as with the Odeon Orfeo, then imo a matching horn makes sense.

Whether that's exciting or not probably depends on whether you have the option of using a much bigger speaker with a much bigger horn or horns. [Glances as Audiophile Bill's avatar and sees where he's coming from]



Mine are oblate spheroids, which have a very precise curve of constantly-changing radius, so they are turned on a lathe. Most of the curvature is within an inch of the throat, not counting the round-over at the mouth. How many loudspeakers with oblate spheroid waveguides are on the market, wooden or otherwise, large or small? If there are others besides Earl Geddes and myself, I am unaware of them.

Of course any "excitement" I might hope this to generate is based on the presumption that the oblate spheroid profile has worthwhile advantages over others. Realistically that's probably a tough sell because they are so uncommon.

Sorry Duke. I was referring to the OMA marketing claim not your use of oblate spheroid, which I do find interesting.

 

[bonzo75]

Hi Duke, the min Phase you mentioned by autotech is an oblate spheroid wave guide. They make it for DIY community and they don't use it in uni but might be using in one of their other models

 

[morricab]

I don’t get the excitement about the marketing claim about a “small” wooden horn. A small wood horn is fairly easy to make if you know what you are doing.

Conical wood horns are the easiest horn of all to construct. Really a very simple process as long as you know what you are doing with a track-saw and it is accurate.

One other reason for a small horn is that it was only for frequencies above 2khz...

 

[Audiophile Bill]

One other reason for a small horn is that it was only for frequencies above 2khz...

For sure but I still don’t see it as a marketing claim per se.

Anyway - never mind. Is what it is.

 

[Duke LeJeune]

Hi Duke, the min Phase you mentioned by autotech is an oblate spheroid wave guide. They make it for DIY community and they don't use it in uni but might be using in one of their other models

Maybe so... doesn't quite look like it to me, but I could be mistaken.

At this page you can see the polar map for Earl Geddes' Summa, which uses an Oblate Spheroid waveguide from about 900 Hz on up. Notice how the pattern width is very uniform from about 1 kHz to about 12 kHz. And what LOOKS LIKE pattern narrowing north of 12 kHz is MOSTLY due to the top end sloping gently downward north of 12 kHz. There's actually only a little bit of narrowing in the top half-octave.

http://www.gedlee.com/Loudspeakers/NS15.aspx (The black contour line is the -6 dB contour)

And here you can see the polar maps of two Min Phase horns. These are big horns, twice the diameter of Earl's, though some of that is round-over. I think the wide-pattern one has a 1" throat and the narrow-pattern one has a 2" throat. Look for the -5 dB contour lines. The wide-pattern one isn't quite constant directivity but it's not bad overall. That looks like a mild resonance at 10 kHz, and then the pattern narrows quite a bit in the top octave. I think we can say that the narrow-pattern one is effectively constant directivity up to about 9 kHz, but imo that 15 kHz resonance should be suppressed in the crossover between mid horn and tweeter, otherwise the speaker system will be singing a duet in the high overtones.

http://horns-diy.pl/horns/minphase/minphase-200/ (The -5 dB contour lines are among the ones labelled)

I think the pattern-narrowing of the Min Phase horns in the top octave or so is a symptom of having less curvature near the throat than an Oblate Spheroid does. Most of the curvature of an Oblate Spheroid is in the first inch or so, aside from the round-over at the mouth.

My 1.4" throat waveguide will have a bit narrower pattern than Earl's 1" throat waveguide, will maintain pattern control down to a lower frequency, and will have nice big round-overs sort of like the Min Phase. If my math is right it will be no bigger than it needs to be, because we could have top-end issues if it gets too big.

 

[morricab]

Maybe so... doesn't quite look like it to me, but I could be mistaken.

At this page you can see the polar map for Earl Geddes' Summa, which uses an Oblate Spheroid waveguide from about 900 Hz on up. Notice how the pattern width is very uniform from about 1 kHz to about 12 kHz. And what LOOKS LIKE pattern narrowing north of 12 kHz is MOSTLY due to the top end sloping gently downward north of 12 kHz. There's actually only a little bit of narrowing in the top half-octave.

http://www.gedlee.com/Loudspeakers/NS15.aspx (The black contour line is the -6 dB contour)

And here you can see the polar maps of two Min Phase horns. These are big horns, twice the diameter of Earl's, though some of that is round-over. I think the wide-pattern one has a 1" throat and the narrow-pattern one has a 2" throat. Look for the -5 dB contour lines. The wide-pattern one isn't quite constant directivity but it's not bad overall. That looks like a mild resonance at 10 kHz, and then the pattern narrows quite a bit in the top octave. I think we can say that the narrow-pattern one is effectively constant directivity up to about 9 kHz, but imo that 15 kHz resonance should be suppressed in the crossover between mid horn and tweeter, otherwise the speaker system will be singing a duet in the high overtones.

http://horns-diy.pl/horns/minphase/minphase-200/ (The -5 dB contour lines are among the ones labelled)

I think the pattern-narrowing of the Min Phase horns in the top octave or so is a symptom of having less curvature near the throat than an Oblate Spheroid does. Most of the curvature of an Oblate Spheroid is in the first inch or so, aside from the round-over at the mouth.

My 1.4" throat waveguide will have a bit narrower pattern than Earl's 1" throat waveguide, will maintain pattern control down to a lower frequency, and will have nice big round-overs sort of like the Min Phase. If my math is right it will be no bigger than it needs to be, because we could have top-end issues if it gets too big.

Min phase and oblate spheroid are not similar really. Min phase looks more like and extreme version of JMLC, which is not constant directivity, like the OS waveguide/horns.

 

[bonzo75]

They are calling the min phase as OSWG