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Horn-Loaded Speakers
Topic: To Romy regarding dipoles

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Posted by Vasyachkin on 03-07-2010
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Romy, i hope this post doesn't offend your sensibilities.  I am not gonna say a word about the physics principles that have led me to the conclusion that this is something that should be tried ( unless you ask of course ). 

The idea i have is a speaker similar to your Macondo but with a few very important differences.  Instead of having having horns fire only forward i was thinking a second identical set of horns firing backward and electrically out of phase.  The ribbon tweeter would have a dipole design - i have developed a technology for such a ribbon:

http://www.diyaudio.com/forums/planars-exotics/154887-plur-2-evolution.html

( or whatever.  Borat = Me.  i am banned from Diy Audio now as Borat as well, so i can't see which is the last thread i had on that technology, but it is all boring and besides the point.  the point is that it is possible to build an open back symmetrical-front-to-back ribbon ( suitable for dipole use ) which would actually have a superior field to regular ribbons which is closed at the back )

ok and finally instead of the sealed bass i would have a dipole bass.

now subjectively everybody who has heard dynamic dipole bass, that i know of, has liked it ( when it is powerful enough, that is when the module is big enough ).  i also haven't come across any feedback that would suggest that opening the back of a ribbon would make it sound worse. the only real questionable aspect here is adding a second set of back firing, inverted phase horns.  mathematically speaking it is what the design "needs" but of course the real question is - what does it sound like ?  that's why i have to ask - has anybody tried this ?

has anybody tried a horn speaker with second set of horns firing back ( in or out of phase ) ?

has anybody tried a horn speaker with a dipole bass section ?

PS: if anybody knows how to separate text into paragraphs let me know pliz.

Posted by haralanov on 03-07-2010
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 Vasyachkin wrote:
the only real questionable aspect here is adding a second set of back firing, inverted phase horns.  mathematically speaking it is what the design "needs" but of course the real question is - what does it sound like ?  that's why i have to ask - has anybody tried this ?

has anybody tried a horn speaker with second set of horns firing back ( in or out of phase ) ?

has anybody tried a horn speaker with a dipole bass section ?

Vasyachkin, in the context of your question, there is a very big difference between bass driver loaded with slow and fast expanding horn contours. The second thing that is not correct in your post - are you talking about low/midbass or upperbass drivers? Also have in mind that your FEMM simulation graphics have very little relevancy with reality when you construct your dipole ribbon tweetter magnet system. The result FEMM shows to you is only magnet lines in static condition and the things are quite different when your speaker motor "see" signal from your amplifier...


Posted by Romy the Cat on 03-07-2010
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I do not exactly understand what you are proposing at DiyAudio site. I have generally an attitude against dipole radiation, and particularly in bass. There is a common believe among audio people that dipole bass has advances, there was a lot of said and written about it and there were many objective (perfectly verifiable) rationalizations brought to support this point of view.  I am familiar with all of them and I also hear a number of good dipole bass systems. I do feel that the people who support dipole bass are clueless and do not know what is important and what is irrelevant.  Their arguments that dipole bass is able to self-EQ the room’s modes sound laughable to me.  The dipole bass, with very characteristic water-down texture never was sounding right to me. This is one of the reasons why I never appreciate the open baffle designs….

In contrary, at higher frequencies dipole might work fine, but no in bass.

The Cat

Posted by Vasyachkin on 03-08-2010
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 haralanov wrote:
Vasyachkin,in the context of your question, there is a very big difference between bass driver loaded with slow and fast expanding horn contours.
perhaps.  but since i don't know much about horns i can't follow what you're saying.
 haralanov wrote:
The second thing that is not correct in your post - are you talking about low/midbass or upperbass drivers?
whichever ones you can maintain directivity control over with the size of horn / waveguide you're willing to use.
 haralanov wrote:
Also have in mind that your FEMM simulation graphics have very little relevancy with reality when you construct your dipole ribbon tweetter magnet system. The result FEMM shows to you is only magnet lines in static condition and the things are quite different when your speaker motor "see" signal from your amplifier...
of course.  goal was to design optimum motor geometry.  if you're worried about inductance / flux modulation i can think of a solution to that, which of course wasn't mentioned in the original write up.

Posted by Vasyachkin on 03-08-2010
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 Romy the Cat wrote:
I do not exactly understand what you are proposing at DiyAudio site.
i can't log in to Diy Audio so i can't view the attached image ( diagram ) files there - can you view them ?  without diagrams it would be really hard to understand.  but basically it was a motor design for a ribbon that is symmetrical - half the motor is in front and half is in the back of the ribbon.  the motivation was to optimize field geometry but a side benefit is that it can be used as a dipole.  there may be some confusion because i redesigned it twice so there were at least three threads about it.  if there is interest i can do a more coherent ( not broken up into 3 pieces with some fallacies in part 1 and 2 ) write up on my own site.
 Romy the Cat wrote:
I have generally an attitude against dipole radiation, and particularly in bass. There is a common believe among audio people that dipole bass has advances, there was a lot of said and written about it and there were many objective (perfectly verifiable) rationalizations brought to support this point of view.  I am familiar with all of them and I also hear a number of good dipole bass systems.
ok.
 Romy the Cat wrote:
I do feel that the people who support dipole bass are clueless and do not know what is important and what is irrelevant.
it is possible.
 Romy the Cat wrote:
Their arguments that dipole bass is able to self-EQ the room’s modes sound laughable to me.

because you don't agree or because you think it is irrelevant ?
 Romy the Cat wrote:
The dipole bass, with very characteristic water-down texture never was sounding right to me. This is one of the reasons why I never appreciate the open baffle designs….
i don't think there are too many people who understand what it takes to produce a good dipole bass section.  it is possible that the reason dipoles sound "watered down" to you is that wrong drivers are used or the system is not big enough.

on the other hand it is also possible that the "watered down texture" is due to dipole radiation pattern itself and there is simply nothing that can be done about it in a dipole.

i recently listened to some older Martin Logans and they did sound cold, lifeless and "extra-terrestrial" - i don't know if that is what you mean by "watered down."  if yes then it may be a matter of personal preference as well as music choice.

it is quite possible that the brain has expectation of certain "colorations" such as room reflections or harmonic distortion, which when missing may sound disturbing.  at least that's my theory regarding MLs.  if so, then it MIGHT go away with time as your brain gets used to the speaker - or it may not, considering that in the studio the track isn't mastered on dipoles.
 Romy the Cat wrote:
In contrary, at higher frequencies dipole might work fine, but no in bass.
at high frequencies my ribbon would have the advantage of a "baffle-less" design too.

Posted by el`Ol on 03-08-2010
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 Romy the Cat wrote:


In contrary, at higher frequencies dipole might work fine, but no in bass.

The Cat
IMO you can never get realistic imaging from dipole.Here is a very detailed description of a dipole horn for the BG Neo 3.

http://www.diyaudio.com/forums/multi-way/159731-beautiful-swingin-speaker.html

Fostex had a midrange magnetostat that has a very good reputation. Also Infinity.I simulated the Blur when you suggested it and I ended up with very low flux densities if it has to be linear. 

Posted by Romy the Cat on 03-08-2010
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Vasyachkin, to say honestly I do not think too much about dipole bass. What I head sounded unacceptable and it was unacceptable not by specific implementation but buy some common character that was characteristic to all dipoles I head.  Loose up some bolt on bass horn and let bass driver to radiate two ways. You will instantly feel hat “relaxed” dipole room loading patter. The same unreasonably relaxed patter I feel with ALL dipole system I ever heard. I personally do not like it and it all that I count.  I do not imply my opinion to be a universal judgment about topology by my estimate of the topology is the only subject that I care and therefore in my own world I have absolutely no interest in dipole applications. I know, some people use audio method to build up universal rules and widespread dogmas.  It is not my objectives, I do audio explicitly for myself and I have all evidences that I need to feel comfortable with detest of acoustic push-pull of bass. So, I will be not the best person to discuss your idea on the subject.

Posted by Vasyachkin on 03-08-2010
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 el`Ol wrote:
IMO you can never get realistic imaging from dipole.

this is almost certainly true.
 el`Ol wrote:
Here is a very detailed description of a dipole horn for the BG Neo 3.
http://www.diyaudio.com/forums/multi-way/159731-beautiful-swingin-speaker.html

very interesting link.  that is more or less what i am suggesting.  i like his conclusion:"I've to confess, never worked with such cheap drivers getting such a reward - I really love that babies!"
 el`Ol wrote:
I simulated the Blur when you suggested it and I ended up with very low flux densities if it has to be linear.

when i first written about it i made the MISTAKE of suggesting that the design could tolerate any ribbon width - i later retracted that.  like i said there were ( i believe ) three threads about it.  the first one indeed ( because it didn't have end metal caps and because it was too wide ) had poor field density.  but the final design had density i think on par with regular ribbons - it is posted somewhere on that site along with field density graphs.

you really have to keep ribbon width to about an inch, just as in regular ribbon designs.  that's the part i initially got wrong.  also the metal end caps increase the field, while making it more linear.

in any case thank you for looking into it.

Posted by Vasyachkin on 03-08-2010
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 Romy the Cat wrote:
Vasyachkin, to say honestly I do not think too much about dipole bass. What I head sounded unacceptable and it was unacceptable not by specific implementation but buy some common character that was characteristic to all dipoles I head.  Loose up some bolt on bass horn and let bass driver to radiate two ways. You will instantly feel hat “relaxed” dipole room loading patter. The same unreasonably relaxed patter I feel with ALL dipole system I ever heard. I personally do not like it and it all that I count.  I do not imply my opinion to be a universal judgment about topology by my estimate of the topology is the only subject that I care and therefore in my own world I have absolutely no interest in dipole applications. I know, some people use audio method to build up universal rules and widespread dogmas.  It is not my objectives, I do audio explicitly for myself and I have all evidences that I need to feel comfortable with detest of acoustic push-pull of bass. So, I will be not the best person to discuss your idea on the subject.
understood.

Posted by KLegind on 03-09-2010
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 Vasyachkin wrote:


has anybody tried a horn speaker with a dipole bass section ?


Well, I must say that I have tried dipole bass in a few configurations, including dipole bass plus horn, however I think this is completely immaterial to the evaluation of dipole bass per se.
Now as to matching dipole bass to a horn midrange is a question og matching tone and dispersion (power response). In my experience you can get good upper bass and very good midrange with dipole bass + horn mid/dipole mid/sealed/whatever depending on choices and talent. What you dont get is bass. There is no deep bass and the mid bass sounds ghostly... I know no other way of describing it really. Occationally it will sound very informative, but it is intellectual and not engaging. Please keep in mind that my experience is not exhaustive. For instance I expect a high Q bass driver to give a sound resembling Quad ELS 67. Maybe some will think it is good sound. I think it is ok sound but not great. I tried open baffle dipole bass with 15 inch drivers and it never sounded right. Now I use semi open baffle speakers with very gradual roundovers to produce upper bass & midrange ~150 to 800 Hz. Mid bass and deep bas will be sealed box with 15" woofers.

Sincerely
Kris


Posted by noviygera on 08-23-2010
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Vasyachkin, if this is still relevant:

I've tried dipole bass and dipole mids with horns mid/highs in my system. If anything, dipole works the WORST for the bass and here's why:
It does not load the room with bass pressure (or bass sound). That's the simple explanation. I've had two 18" woofers running up to 150Hz in H-cabs in a medium size room and even though there is decent output -- it's like listening in headphones. You can get a 30Hz tone sound but there is absolutely no physical pressure in creating the bass "feel" because the pressure is immediately canceled out by the out of phase signal from the back of the driver. So you get detailed, clean, but lifeless bass. This will get on your nerves after a while. Took about two year for me.

Here's my take on dipole bass
Pros: even bass coverage in room, lean, deep, detailed bass.
Cons: lifeless, does not match the sound pressure of horn loaded drivers

What you should try if dipole seems appealing to you is "infinite baffle" subs. This works a lot better in my opinion, even if using the same exact drivers. I tried it, by taking the same 18" drivers I used for dipole by mounting them in the wall, using the other room as the box. This worked much better for bass than dipole. Now I feel the bass, not just hear it.

P.S. dipole worked much better in the range of 150 to 1000Hz. That is the only good use of dipole.

Herman

Posted by KLegind on 08-24-2010
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 noviygera wrote:
Vasyachkin, if this is still relevant:

I've tried dipole bass and dipole mids with horns mid/highs in my system. If anything, dipole works the WORST for the bass and here's why:
It does not load the room with bass pressure (or bass sound). That's the simple explanation. I've had two 18" woofers running up to 150Hz in H-cabs in a medium size room and even though there is decent output -- it's like listening in headphones. You can get a 30Hz tone sound but there is absolutely no physical pressure in creating the bass "feel" because the pressure is immediately canceled out by the out of phase signal from the back of the driver. So you get detailed, clean, but lifeless bass. This will get on your nerves after a while. Took about two year for me.

Here's my take on dipole bass
Pros: even bass coverage in room, lean, deep, detailed bass.
Cons: lifeless, does not match the sound pressure of horn loaded drivers

What you should try if dipole seems appealing to you is "infinite baffle" subs. This works a lot better in my opinion, even if using the same exact drivers. I tried it, by taking the same 18" drivers I used for dipole by mounting them in the wall, using the other room as the box. This worked much better for bass than dipole. Now I feel the bass, not just hear it.

P.S. dipole worked much better in the range of 150 to 1000Hz. That is the only good use of dipole.

Herman


Well, I have to say that your description is spot on, except for the phrase "Pros: even bass coverage in room, lean, deep, detailed bass.
". I dont think it really covers the problem with dipole bass in one important area; and that is Tone. Yes, it is dull and lifeless but there is more to it than simple pressure. Dipole has trouble doing bass that has full and round and soft tone. It can do hard bass sort of... but it is much more intellectually appealing than truly satisfying.

Best
Kris

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