Of course enclosure shape can (as in 'can' not 'automatically does') make a difference to the internal behaviour, as anybody who designs and builds horns, quarter-wave or any other box type should be well aware of. A diffusing / spreading of internal eigenmodes, especially if what remain are shifted higher in frequency, will allow a reduction in internal damping requirements relative to a box with a handful of strong eigenmodes at a lower frequency, since they are easier to attenuate. Not exactly news, and one reason why acoustic ratios, be they Golden or one of the others, have regularly been employed in box speakers for donkey's years. Likewise, external shape impacts upon diffraction behaviour, a matter thoroughly investigated by Olson at RCA and the vast resources available there and at WE from the 1920s onward. In both cases, this shape should do a decent job. What it does not do is operate in a different physical reality as-yet unknown to woman-born.
I'm in the same boat, I've been using time (also mostly due to family and house obligations) and space limitations for years as an excuse not to pursue my love of building audio systems. I'm finally seeing a way I can make it happen, you are an inspiration for me. I also am very interested in the measurement of the systems I build, otherwise how will I be able to make objective evaluations of different designs? Could you describe the setup you have so I may look into making my own?
Foam core prototypes are the way to go for quick builds. Armed with nothing more than a straight edge, ruler, pencil, xacto, utility knife, hot melt glue gun, you can build speakers quickly and inexpensively. They happen to sound good too🙂 no sawdust, no dangerous power tools, no workshop needed.
You should get wire strippers and crimpers for fast work of the driver quick connect terminals.
For measurement I use an old laptop PC (actually a small netbook), REW software, a Dayton UMM-6 USB mic. I use a small class D amp (TPA3116D2) between the netbook and the speaker. If you can get the Dayton DATS v2 - it can be very useful for impedance measurement of speaker and TS parameter measurement.
I assume you have a PC and an amp already. You just need the $70 mic and you are set. Other amps such as a $5 TDA7297 work well too. Just needs to have sufficiently flat output to drive the load from your speaker from say 30Hz to 20kHz.
Let me know if you need more tips. That REW software is fantastic. Can't believe it's free.
Good luck,
X
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Thanks gpapag that is exceptionally informative! I always wondered about that design -- especially when I began looking for other speakers based on dodecahedra.
You are welcome.
I hope the writer provides a correct description ( I’ve read different stories for the D-12, but not as detailed as this).
If the Peerless mid range is the one I know ( the one with the thick metal walled cylindrical rear box and the black cloth corrugated surround suspension), I don’t think it will live comfortably at low mids with an 750 Hz 6dB/ oct HP crossing.
George
I hope the writer provides a correct description ( I’ve read different stories for the D-12, but not as detailed as this).
If the Peerless mid range is the one I know ( the one with the thick metal walled cylindrical rear box and the black cloth corrugated surround suspension), I don’t think it will live comfortably at low mids with an 750 Hz 6dB/ oct HP crossing.
George
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I realize that my background in theoretical physics rather than practical audio engineering may often lead me to use different terminology than some engineers are used to. It is also due to my tendency to focus not upon the mechanics of particular transducers, but upon the behavior of air inside loudspeaker cabinets.
It is far easier to see the motion of a woofer than the motion of air molecules inside a speaker enclosure. For those who might be used to different terminology than mine, I'd like to recommend this excellent Web page by Dr. Russell at Penn State University on the picturing of standing wave modes. It has several excellent animations illustrating the relationship of pressure nodes to displacement antinodes:
Standing Sound Waves (Longitudinal Standing Waves)
It is far easier to see the motion of a woofer than the motion of air molecules inside a speaker enclosure. For those who might be used to different terminology than mine, I'd like to recommend this excellent Web page by Dr. Russell at Penn State University on the picturing of standing wave modes. It has several excellent animations illustrating the relationship of pressure nodes to displacement antinodes:
Standing Sound Waves (Longitudinal Standing Waves)
Tesserax,
I Should have edited post#347 to include this line:
'I shall use this quote next time some one tells me they have had "Bi-turbo's and a triple powerband fitted" to their motorbike / car.'
It would be most gauche of me to question your knowledge base Unless one happened to be sprouting utter tripe and to do so on an open forum is would, in my mind, be a lowering of my moral standards and if I have caused annoyance to you, I apologise sincerely.
I have 3 Masters degrees that allow me to speak total and utter horse droppings about Art and Printing, my physics 'knowledge' was battered into me from the age of 4yrs whenever I asked 'Why is it Daddy?' of my late father, qualified to sit in the 'right hand seat' of 'doom tubes' (AKA Nimrods) cockpits, but as he started his R.A.F. career as a 'Ground Radar' tech, he spent most of his air-born time in the ground /air radar tent calling 'Blue - Blue..... RED'.
Heres 3 pictures of me using physics while at work:
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I Should have edited post#347 to include this line:
'I shall use this quote next time some one tells me they have had "Bi-turbo's and a triple powerband fitted" to their motorbike / car.'
It would be most gauche of me to question your knowledge base Unless one happened to be sprouting utter tripe and to do so on an open forum is would, in my mind, be a lowering of my moral standards and if I have caused annoyance to you, I apologise sincerely.
I have 3 Masters degrees that allow me to speak total and utter horse droppings about Art and Printing, my physics 'knowledge' was battered into me from the age of 4yrs whenever I asked 'Why is it Daddy?' of my late father, qualified to sit in the 'right hand seat' of 'doom tubes' (AKA Nimrods) cockpits, but as he started his R.A.F. career as a 'Ground Radar' tech, he spent most of his air-born time in the ground /air radar tent calling 'Blue - Blue..... RED'.
Heres 3 pictures of me using physics while at work:
Sippy,
I am impressed with anyone who had earned 3 masters degrees in anything. I certainly haven't. I am sorry if I seemed condescending or defensive in my last post. It wasn't because of you. I was reacting to someone else's post who quoted "displacement antinode" as if it were an outlandish term I had made up, calling it "dubious pseudoscience" . I know I can come off sometimes sounding like I think I can somehow rewrite the laws of acoustics without paying my dues in audio engineering.
I have a lot of respect for the RAF. My own father was a US Navy jet pilot, and sometimes I wish my poor vision had not ensured I could never follow in his footsteps. (I am like 20/300 plus astigmatism). I remember him despairing at trying to pound into me that 2 pi r is the same as pi D when I was just a lad.
I envy you your skill at applying physics on the water. I never learned how to surf but is is one of the coolest activities. I am a klutz even on a skateboard.
I am impressed with anyone who had earned 3 masters degrees in anything. I certainly haven't. I am sorry if I seemed condescending or defensive in my last post. It wasn't because of you. I was reacting to someone else's post who quoted "displacement antinode" as if it were an outlandish term I had made up, calling it "dubious pseudoscience" . I know I can come off sometimes sounding like I think I can somehow rewrite the laws of acoustics without paying my dues in audio engineering.
I have a lot of respect for the RAF. My own father was a US Navy jet pilot, and sometimes I wish my poor vision had not ensured I could never follow in his footsteps. (I am like 20/300 plus astigmatism). I remember him despairing at trying to pound into me that 2 pi r is the same as pi D when I was just a lad.
I envy you your skill at applying physics on the water. I never learned how to surf but is is one of the coolest activities. I am a klutz even on a skateboard.
Tesserax,
My soul is gladdened by you post...... my father was 'endless' on '2 pi r = 2 pi d'.
Surfing is one of those things you either do or dont do. I wish I could help those that cant for whatever reason.
I do it a lot, surfing is my work and boards also, I gave up my trades to face my fears and live a few dreams.
xrk971,
my post was not for you, unless your name also happens to be 'Tesserax'......
Sippy,
Just wasn't sure what the 'biturbo and powerband' comment came from... Neat that surfing is your business. I used to surf at San Onofre nuke power plant (South of Los Angeles) back in the day.
Just wasn't sure what the 'biturbo and powerband' comment came from... Neat that surfing is your business. I used to surf at San Onofre nuke power plant (South of Los Angeles) back in the day.
Emperors New Clothes....
Hi Tesserax,
Very interesting link....Its great to 21st century R&D and computing power used to debunk so much of the 19th century (!) and early 20th century experiments that are still raised aloft by the vast majority of the loudspeaker industry and DIY community....
Sadly this "Emperors New Clothes" syndrome prevails and is a major driver behind the loudspeaker industry stagnation....
We see huge scientific advances in every walk of life and yet in the loudspeaker world 100 year old horn designs are still competitive with the best that the top 10 global players can manage.....
Its time to move on from the 1920's guys.....Would you accept this state of affairs in the world of medicine, aviation, computing, electronics, military (well ok not good we can now kill millions with 1 bomb)???
I have attached a couple of recent papers by John Watkinson in which he describes state of industry....The Emperors New clothes syndrome.
He also debunks the 100 year old bad joke of transmission line & ported designs....Vested interests will of course hate this...! 😀
Cheers
D.
Hi Tesserax,
Very interesting link....Its great to 21st century R&D and computing power used to debunk so much of the 19th century (!) and early 20th century experiments that are still raised aloft by the vast majority of the loudspeaker industry and DIY community....
Sadly this "Emperors New Clothes" syndrome prevails and is a major driver behind the loudspeaker industry stagnation....
We see huge scientific advances in every walk of life and yet in the loudspeaker world 100 year old horn designs are still competitive with the best that the top 10 global players can manage.....
Its time to move on from the 1920's guys.....Would you accept this state of affairs in the world of medicine, aviation, computing, electronics, military (well ok not good we can now kill millions with 1 bomb)???
I have attached a couple of recent papers by John Watkinson in which he describes state of industry....The Emperors New clothes syndrome.
He also debunks the 100 year old bad joke of transmission line & ported designs....Vested interests will of course hate this...! 😀
Cheers
D.
second document too big a file...
The second of johns documents is too big a file....PM me if you want a copy.
Cheers
D.
The second of johns documents is too big a file....PM me if you want a copy.
Cheers
D.
Hi,
I've no problems with the term "Displacement Antinode",
only what it is allegedly reffering to, which is clear as mud.
Its clear a box has standing modes. Say you triangulate
it bottom front to top rear. Some might think this hasn't,
but a simple reflection with take you back to a parallel
walled box, so it does but they are shifted in frequencies.
Its pretty clear this box shape would need multiple
reflections to get to some sort of parallel arrangement,
so it doesn't have "box" fundamental standing waves.
Nodes and antinodes are properties of standing waves,
Its very hard to claim to have one without the other.
(Whether they are pressure or displacement types).
I'll repeat that a training in "Theoretical Physics"
is no excuse for having worse real basic physics
than that used by engineers, and theoretical
physics is not carte blanche to re-inteprete
basic well known physics as an opinion.
rgds, sreten.
FWIW bi-turbo's are all too real, and so are
double powerbands, a triple is possible ....
I've no problems with the term "Displacement Antinode",
only what it is allegedly reffering to, which is clear as mud.
Its clear a box has standing modes. Say you triangulate
it bottom front to top rear. Some might think this hasn't,
but a simple reflection with take you back to a parallel
walled box, so it does but they are shifted in frequencies.
Its pretty clear this box shape would need multiple
reflections to get to some sort of parallel arrangement,
so it doesn't have "box" fundamental standing waves.
Nodes and antinodes are properties of standing waves,
Its very hard to claim to have one without the other.
(Whether they are pressure or displacement types).
I'll repeat that a training in "Theoretical Physics"
is no excuse for having worse real basic physics
than that used by engineers, and theoretical
physics is not carte blanche to re-inteprete
basic well known physics as an opinion.
rgds, sreten.
FWIW bi-turbo's are all too real, and so are
double powerbands, a triple is possible ....
Hi,
The link is bog standard acoustic engineering
stuff that has been known for centuries.
Its not remotely interesting to the informed.
Your suffering from ENCS and peddling nonsense.
rgds, sreten.
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Hi Overkill,
Glad you're still with us. You might find it interesting that the tuning of the preset/settings I use with my speaker/room correction are based on psychoacoustics and aim to make the system more "blameless". Also I sympathize with you in regards to transmission line/ported speakers. I don't care for group delay in the bass nor do I like too steep of a descent (with the associated ringing).
Glad you're still with us. You might find it interesting that the tuning of the preset/settings I use with my speaker/room correction are based on psychoacoustics and aim to make the system more "blameless". Also I sympathize with you in regards to transmission line/ported speakers. I don't care for group delay in the bass nor do I like too steep of a descent (with the associated ringing).
Indeed.
Yup, those things.
Still cant go to Halfords to buy a powerband To fit your import EK Civic.
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