Paul McGowan on Horn Loudspeakers

the sound of Tao

Well-Known Member
Jul 18, 2014
3,620
4,838
940
Did you upgrade the compression drivers?
After a conversation with Audiophile Bill a little while back I’m heading in a fairly different direction. He introduced me to the wonderful world of baffle research (I thought I was already fairly baffled lol) and has inspired me to rethink what I was doing and am now going to use them in a new build asymmetrical folded baffle. It’s a way more involved project and I’ve underestimated what time it would take me but I think that the initial research and first phase of the design process itself is a good part of the fun for me.

I’ve drawn up the asymmetrical baffles and done a bit of 3D modelling to get a feel for the overall form factor and sense of scale and am now feeling good with the direction of the early iterative sketches… working out of symmetry it’s harder to get the overall balance right but as a landscape designer we work more often with asymmetry so there was immediate attraction in Bill’s idea and working in 3D makes this easier…I’m happy with that at an initial level so next up is getting the metal frames fabricated up when the trades return in the New Year so I can begin trialling the OB folded wings.

The isobaric OB sub is actually a parallel spin off project of the new build. I’m keeping with using a modular approach with the design so I have options to reconfigure and if I feel the need even to compare in other drivers. I’ve got the big quintet OB horn here which I love and can use as the reference in benchmarking the new build against a proven OB design in both measurements and in listening. Where it goes to from there I’m not sure… it is a work in progress and design process is something I am lucky enough to work with all the time. For me it’s much like riding a dragon, you hop on and it ultimately takes you where it takes you.
 
Last edited:

tima

Industry Expert
Mar 3, 2014
5,777
6,819
1,400
the Upper Midwest
One of the advantages of ours being a hobby in senescence is that many here have been at it for a long time and have possibly largely answered for themselves (some exactly and for others in their essential directions) with the strategy of their preferred gear types.

The problem becomes when people get into active conversion mode trying to propagate their tailored solutions to others in other circumstances already largely convinced in their own preferences based on different needs and with different questions.

That idea that we are here looking for our own solutions to slightly varying (and possibly evolving) kinds of individual questions means we are actually just travelling in slightly parallel universes with just a bit too much spooky action perhaps still happening at a distance.

Yes, audiophiles as solitary contemplative individuals (or egoistic prigs) with the grooves of experience written on their foreheads, answering for themselves, for their ow unique solutions -- yes, there is that picture. Still - there's a lot to be learned by listening to certain others (not everyone) and a willingness to try what one does not self-invent can lead to new rewards. You can teach old dogs older tricks.
 
  • Like
Reactions: orfeo_monteverdi

Ron Resnick

Site Co-Owner, Administrator
Jan 24, 2015
16,017
13,346
2,665
Beverly Hills, CA
The problem becomes when people get into active conversion mode trying to propagate their tailored solutions to others in other circumstances already largely convinced in their own preferences based on different needs and with different questions.

+1
 

Lagonda

VIP/Donor
Feb 3, 2014
3,422
4,673
1,255
Denmark
I have no sympathy with that argument even though there may be some truth in it. An onmi speaker is rather like an orchestra - its sound is widely dispersed so that listeners in all parts of the auditorium (not just centre stalls) can fully enjoy the music. This is surely the main aim of an onmi system? The guy sitting in the ideal listening spot gets no significant advantage over those in other parts of the room.

The reason I considered a move to omnis can be illustrated by my room's layout. The sound received at my dining or kitchen area is not at all good from my horns. There is little top end and all excitement in the music is lost. With omnis, the sound in these areas should be similar to the sound in the main listening area.

However, as I mentioned earlier, the loss of imaging (even at the best listening position) with onmis is not something I'd put up with.

Also I suspect the only type of speakers that can cope with the room’s physical features (acres of curved floor-to-ceiling glass, etc) without resorting to unwanted signal processing is the very directional horn.
Most omnis and planars need a solid wall behind them to reinforce the bass wave, i don't think MBL's (or Martin Logan) would work in that space. Do you have a picture of the room ? It looks like a beautiful layout ! :)
 

morricab

Well-Known Member
Apr 25, 2014
9,391
4,986
978
Switzerland
Most omnis and planars need a solid wall behind them to reinforce the bass wave, i don't think MBL's (or Martin Logan) would work in that space. Do you have a picture of the room ? It looks like a beautiful layout ! :)
The bass on your MBLs is not Omni is it? I thought it was a band pass box?
 
  • Like
Reactions: Alrainbow

Lagonda

VIP/Donor
Feb 3, 2014
3,422
4,673
1,255
Denmark
The bass on your MBLs is not Omni is it? I thought it was a band pass box?
The football shaped mid-bass driver sounds like shit if it does not play in relative close proximity of the wall, somewhere between 1 m and 1,5 m in my experience. I don't use the sub driver in my setup at all. :)
 

the sound of Tao

Well-Known Member
Jul 18, 2014
3,620
4,838
940
Yes, audiophiles as solitary contemplative individuals (or egoistic prigs) with the grooves of experience written on their foreheads, answering for themselves, for their ow unique solutions -- yes, there is that picture. Still - there's a lot to be learned by listening to certain others (not everyone) and a willingness to try what one does not self-invent can lead to new rewards. You can teach old dogs older tricks.
Using precedents and learning from others is best practice and we are always standing on the shoulders of others and in one form or another in the process of some kind of reapplication, reinvention or re-contextualisation in everything.

I’m heavily invested in learning… the culture of shared understanding enlivens any group. So we can definitely always learn off others… that I do love.

There are quite a few here doing great things but I suppose as I get more and more niche focussed over time that becomes a smaller number of bigger interests for me as well.

Then add to that the people whose work most interests me here aren’t necessarily doing things that I can afford or involved in approaches that are applicable or in a viable pathway for me. But yes, the learning never ends.
 
  • Like
Reactions: AudioHR and tima

godofwealth

Well-Known Member
Feb 8, 2022
571
874
108
63
I recall in the mid 1980s as a grad student in Pittsburgh visiting a rural audio dealer in Butler county who was demoing a pair of Morrison Audio Model 1 loudspeakers, an omni-directional speaker designed by Stuart Hegeman. HP in TAS raved about early version calling it the best small loudspeaker on the planet. The sound is projected upwards — notice the tweeter diffuses through a conical structure. The bass module is a transmission line. It sounded quite nice. It was spookily real in a non-Hi-Fi way.

1672890282552.jpeg

In my bedroom, I have a much later modern version designed by the Danish company Gradient called the Helsinki. My Gradients also project the sound up, to minimize floor reflections. But mine are not omni-directional. Quite the contrary, they are intended to absolutely minimize room effects. The 12” woofer is an open baffle design. There’s no cabinet sound because there’s no cabinet. The tweeter is horn loaded. On a well recorded classical album, it sounds spookily like you’re in the orchestra hall. Robert Greene in TAS and Art Dudley in Stereophile both liked it, but said it was very dependent on how you placed it in a room.

D554BCCF-1B2B-4867-95E1-D418A5247088.jpeg
 
  • Like
Reactions: AudioHR

adrianywu

Well-Known Member
Nov 15, 2021
564
670
108
57
In the first underlined part… is it possible that the distoprtion might be a consequence of the 10x lower excursion?
And then it implies that the distortion is a consequence of the mass AND the excursion?
(I can believe exursion a bit easier than the ,mass part, as being a causal mechanism.)

In the second underlined part, are you referring to the Hz or the diaphragm speed?
(I am assuming the later case.)
The distortion of loudspeaker drivers is partly due to non-uniformity of the magnetic field within the gap. Some voice coils are so called overhung, which means a part of the voice coil is outside the magnetic field at maximum excursion. As you can imagine, if the area of the coil covered by the magnetic field is variable, the movement of the coil would not be uniform, i.e. distorted. In any case, by virtue of the way the gap is configured, the field becomes less uniform towards the edges. If the coil movement is confined to the most uniform part of the field, there will be less distortion. Most commercial drivers have voice coils that move within the entirety of the gap, or even travel outside the gap as mentioned above. This is to maximise output at the expense of higher distortion.
The mass in itself does not introduce distortion, since it remains constant throughout the cycle. However, it will take more time to move a heavier mass (force = mass x acceleration) up to speed, and more time to stop it. Hence, "slower". This translates into poorer transient response.
 

Hear Here

Well-Known Member
Feb 14, 2020
735
433
155
Portsmouth, UK
Most omnis and planars need a solid wall behind them to reinforce the bass wave, i don't think MBL's (or Martin Logan) would work in that space. Do you have a picture of the room ? It looks like a beautiful layout ! :)
Yes, a difficult room acoustically, but otherwise great. You see why I didn't want to keep the big Quads!
 

Attachments

  • Plan - 112 Living Room.pdf
    70.9 KB · Views: 14
  • 20210708_185716.jpg
    20210708_185716.jpg
    625.4 KB · Views: 54
  • Like
Reactions: Lagonda

Lagonda

VIP/Donor
Feb 3, 2014
3,422
4,673
1,255
Denmark
Yes, a difficult room acoustically, but otherwise great. You see why I didn't want to keep the big Quads!
Wow ! What a view ! :)
 

Holmz

Active Member
Apr 19, 2022
136
47
33
63
The distortion of loudspeaker drivers is partly due to non-uniformity of the magnetic field within the gap. Some voice coils are so called overhung, which means a part of the voice coil is outside the magnetic field at maximum excursion. As you can imagine, if the area of the coil covered by the magnetic field is variable, the movement of the coil would not be uniform, i.e. distorted. In any case, by virtue of the way the gap is configured, the field becomes less uniform towards the edges. If the coil movement is confined to the most uniform part of the field, there will be less distortion. Most commercial drivers have voice coils that move within the entirety of the gap, or even travel outside the gap as mentioned above. This is to maximise output at the expense of higher distortion.

Yep I agree.
Those new Purifi drivers go along ways in line raising the BL curve.

The mass in itself does not introduce distortion, since it remains constant throughout the cycle. However, it will take more time to move a heavier mass (force = mass x acceleration) up to speed, and more time to stop it. Hence, "slower". This translates into poorer transient response.

^This part^ I do not get.

Let’s say a woofer plays a 1000 Hz tone, but is crossed over at 500Hz.
Same with the MR,
It is only the tweeter that could possibly get to a point where it wants to play past 20klHz or past its rated upper limit.
So the ensemble will have all the transcient response that is required up to 20kHz.

The sound is really only affected by the acceleration, and the sound pressure is only only affected by acceleration.
The velocity and excursion is only a consequence of the acceleration, so it is a massive issue with a woofer and less so for a MR, and with a tweeter the excursion is almost always pretty small.

The order of the box will totally dominate the transcient response,
(I think that a baffle is 1st order, a sealed is 2nd order, and the TR gets worse as we go to 4th order.)
 

adrianywu

Well-Known Member
Nov 15, 2021
564
670
108
57
Yep I agree.
Those new Purifi drivers go along ways in line raising the BL curve.



^This part^ I do not get.

Let’s say a woofer plays a 1000 Hz tone, but is crossed over at 500Hz.
Same with the MR,
It is only the tweeter that could possibly get to a point where it wants to play past 20klHz or past its rated upper limit.
So the ensemble will have all the transcient response that is required up to 20kHz.

The sound is really only affected by the acceleration, and the sound pressure is only only affected by acceleration.
The velocity and excursion is only a consequence of the acceleration, so it is a massive issue with a woofer and less so for a MR, and with a tweeter the excursion is almost always pretty small.

The order of the box will totally dominate the transcient response,
(I think that a baffle is 1st order, a sealed is 2nd order, and the TR gets worse as we go to 4th order.)
The "speed" of the tweeter is in fact very important. This is why ribbon and electrostatic drivers are often used for tweeters. The best tweeters are probably the ionic (or plasma) tweeter, which has no mass. With high frequencies, there is less time to accelerate and decelerate the diaphragm. That's why electrostatic panels are pretty much the only drivers capable of reproducing a square wave.
 
  • Like
Reactions: Holmz

Bill Hart

Well-Known Member
May 11, 2012
2,683
174
1,150
I recall in the mid 1980s as a grad student in Pittsburgh visiting a rural audio dealer in Butler county who was demoing a pair of Morrison Audio Model 1 loudspeakers, an omni-directional speaker designed by Stuart Hegeman. HP in TAS raved about early version calling it the best small loudspeaker on the planet. The sound is projected upwards — notice the tweeter diffuses through a conical structure. The bass module is a transmission line. It sounded quite nice. It was spookily real in a non-Hi-Fi way.

View attachment 102548

In my bedroom, I have a much later modern version designed by the Danish company Gradient called the Helsinki. My Gradients also project the sound up, to minimize floor reflections. But mine are not omni-directional. Quite the contrary, they are intended to absolutely minimize room effects. The 12” woofer is an open baffle design. There’s no cabinet sound because there’s no cabinet. The tweeter is horn loaded. On a well recorded classical album, it sounds spookily like you’re in the orchestra hall. Robert Greene in TAS and Art Dudley in Stereophile both liked it, but said it was very dependent on how you placed it in a room.

View attachment 102549
I remember the first speaker you showed, and I think I may have met the guy who designed it- I was a college drop out slinging hi-fi in the 'Burgh in '73. He was a nice man-- drove what would have been considered a compact car in the mid-70s-light blue- today it would be considered huge. Was that Stu Hegeman? There were the Curley Brothers in Butler too- Mike collected vintage Ferrari racing cars before that was a "thing." Crazy bast'd. Brilliant guy, though. Did Opus One (Tasso Spanos) also have a store out there? He was the Le Maitre of the audio salon scene in that city- a gracious, charming man.
 

BruceD

VIP/Donor
Dec 13, 2013
1,509
576
540
When I was working in NY same time late 70's, Jon Seider (Harvey Rosenbergs engineer ) and myself drove out to see Stew Hegerman
and listen to some of his superb Westminter master tapes--yes those were the Speakers pictured above used-- Sources included were the Citation Amp-he had hand in designing and his cute little Hapi One Preamp--I bought that ! :D
I'll always recall the sonics so pure. He was a very warming and open man--he wasn't in the best of health at the time I'd hazard .

Memorable experiences though not easy passed,

BruceD
 
Last edited:

jonathanhorwich

Well-Known Member
Nov 24, 2010
68
46
923
Chicago
Thanks for initiating this thread, Ron, and for your counter reply to Mr. McGowan.

Paul is correct that with only low wattage tube amps available back in the day, speakers had to be very efficient to convert those meager watts into high acoustic output, and hence they needed to be horn-loaded and very large. Bear in mind that those speakers had to fill out very large listening spaces like cinemas etc., and in that light it's quite impressive what they were able to do with only so much amp power at hand.

Today however prodigious amp power can be had in almost unlimited quantity - actually it's an inverted scenario compared to the development in speaker sensitivity over the years, certainly for domestic use: modern amps, not least Class-D variants are now much more efficient producing watts - i.e.: with less heat, lighter in weight and using less power to make more power. This again goes hand-in-hand with the considerably smaller and low efficiency speakers of today that are in need of more power, though not necessarily calling for the most efficient amp topology around today.

One thing though is the better efficiency of modern amps to produce more power, but at the receiving end at the speakers watts are still watts; only so much heat can be dissipated before thermal issues arise, not least and likely more relevantly as an audible effect in the transient domain. I think of it as a 1-10W light bulb compared to a 100-1kW ditto - this is how it's handled in the voice coil and passive cross-over components of the speakers as it applies to their very efficient vs. low efficiency iteration for a given SPL.

That is to say: one doesn't just freely compensate low efficiency in speakers with more amp power, as it comes with a price: heat build-up and eventually thermal compression, or (and I believe this term was "coined" by Mr. @Duke LeJeune): thermal modulation, which relates to the dulling of transient behavior due to "peak heat-up" as the perhaps more prevalent and audible side effect vs. compression that ends up frying the VC's and XO components due to excessive heat.

As a statement against the need for high efficiency many an audiophile appears to point at the rarity of the latter scenario (thermal compression) in the paragraph above, while failing to realize the former (thermal modulation) - a sentiment I believe applies to Mr. McGowan. The less restricted transient behavior in high eff. speakers typically comes off as an "aliveness" or sense of ignition in their sound, which may also be described with a better micro dynamic ability, also audible at lower SPL's.

Acoustic transformers, which horns essentially are, doesn't always across without imposing their own sonic imprinting, be that for reasons of the horn profile itself, material resonances (and their nature/frequency) or other. That 'other' may also have to do with their dispersive nature and the degree of reflected vs. direct sound, as well as the way their cone/diaphragm couples to the air and excites it compared to a direct radiator. The latter aspects are differences in presentation, but even so may be misconstrued as colorations or other unwanted horn artefacts that are really just about what differs from the habitual exposition to low eff. direct speakers where reflected sound is more prominent.

Do we need high sensitivity in speakers in domestic milieus today with the plentiful of amp power at hand? Yes, I most certainly believe we do, as hopefully some of the above explains. While I wouldn't necessarily pair them exclusively with low wattage amps (but also with higher powered solid state variants, actively), it seems to me this segment of speakers, usually horn-loaded, potentially offer qualities more inherently linked to a live-like, physically immersive presentation that smaller, low eff. direct radiating speakers simple can't replicate.
This is extremely informative.
 

cfgardei1

Member
Nov 8, 2022
40
15
10
60
Sometimes an over-simplification "says it all". Here goes:

1) The ONLY person whose opinion matters is yourself (unless arguing is your preferred form of entertainment)
2) LOUD speakers are generally efficient / GOOD speakers are generally inefficient.
3) ALL ELSE BEING EQUAL, the more amplifier power: the better -- regardless of whether your speakers are efficient or not
4) Decide which of #2 is most important to you RIGHT NOW, knowing it can reverse at any time of your choosing
5) Own two systems: one GOOD and one LOUD and, based on #4, choose which one you'll listen to now.

For example: yesterday I listened to some jazz and progressive rock on my 3.7i's (Magnepan); Tomorrow, I may do more of the same OR I may go downstairs and play Metallica on my Klipsch system
 

Hear Here

Well-Known Member
Feb 14, 2020
735
433
155
Portsmouth, UK
Sometimes an over-simplification "says it all". Here goes:

1) The ONLY person whose opinion matters is yourself (unless arguing is your preferred form of entertainment)
2) LOUD speakers are generally efficient / GOOD speakers are generally inefficient.
3) ALL ELSE BEING EQUAL, the more amplifier power: the better -- regardless of whether your speakers are efficient or not
4) Decide which of #2 is most important to you RIGHT NOW, knowing it can reverse at any time of your choosing
5) Own two systems: one GOOD and one LOUD and, based on #4, choose which one you'll listen to now.

For example: yesterday I listened to some jazz and progressive rock on my 3.7i's (Magnepan); Tomorrow, I may do more of the same OR I may go downstairs and play Metallica on my Klipsch system
That's a pretty inaccurate summary. In particular 2) is just simply wrong. How did you reach these crazy beliefs?
 
  • Like
Reactions: Skanda and morricab

cfgardei1

Member
Nov 8, 2022
40
15
10
60
RE: "Crazy beliefs" - I guess you're one of the "arguing as form of entertainment" types...

Please name for me:
A) ANY speaker that sounds REALLY good that is efficient (100+db @ 1 watt @ 1 meter).
OR
B) ANY 100+db efficiency speaker that sounds REALLY good.

Points of reference:
A) I think that my 3.7's sound REALLY good. You may or may not agree (but you'd be firmly in the minority if you didn't). The problem is they are around 86dB efficient. And, I don't care if you have 10,000 watts per channel: they will melt down before they get LOUD. (120db would require 2200 watts, each - which they clearly won't take.)

B) My Klipsch Jubilee's get REALLY loud (anyone wanting to test that theory should probably schedule an ear test).

BUT, even though they sound "Good" by most people's definition, they can't hold a candle to the 3.7's on detail, definition, soundstage, etc. etc.

Before your rebuttal, please re-read my original post: I said "generally" on both, meaning there remains the possibility of an exception or two. (But these exceptions are "GENERALLY" unafforable!)

Point of reference: The Legacy Valors ($86,000) I recently heard DO sound very good and they DO get quite loud.

But:
A) They're $86,000! Add the price of running a dedicated power line to them if you really want to do them justice.
B) They are NOT quite as good at the "detail, definition, soundstage, etc. etc." previously mentioned about the 3.7's
C) They won't get as loud as the K horns.
 

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. This is THE place where audiophiles and audio companies discuss vintage, contemporary and new audio products, music servers, music streamers, computer audio, digital-to-analog converters, turntables, phono stages, cartridges, reel-to-reel tape machines, speakers, headphones and tube and solid-state amplification. Founded in 2010 What’s Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals, we enjoy learning about new things and meeting new people, and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing