Can someone point me toward some scholastic research on the effects of full range drivers vs. multi-way systems? I'm wanting to write a research paper on this subject but the main sources for information on full range drivers tends to be forums like this one and informal statements on full range enthusiast websites. I'm sure people in this forum know of great research papers and scholars that have commented on the subject - I'm just wanting to tap that source of information. Any help/suggestions is greatly appreciated.
Just to clarify, I'm looking for information on subjects like cone breakup, phase distortion of crossovers (actually I'm able to find a lot on this), intermodulation distortion, high-frequency beaming, point source localization, etc... I'm sure there's a few more subjects to mention but any areas of great formal discussion or testing in a peer-reviewed context would be great.
If you find any, please post.
I have a substantial audio library you are welcome to peruse (AES and aXp going back to something like 1972), and a visit to the mountain is always a good opportunity tolisten to a range of fullrangers.
An AES membership, and a subscription to full access to the AES electronic library would give you access to AES papers & preprints (at least the newer ones).
dave
I have a substantial audio library you are welcome to peruse (AES and aXp going back to something like 1972), and a visit to the mountain is always a good opportunity tolisten to a range of fullrangers.
An AES membership, and a subscription to full access to the AES electronic library would give you access to AES papers & preprints (at least the newer ones).
dave
I've been trying to search through aes journals but they've shown little to no fruitful results. I'm an SFU student so I can access the journals but not their e-library where the conference papers are. From what I've found those papers might have more info...
I'll certainly post any results and a copy of my final paper.
I'll certainly post any results and a copy of my final paper.
That doesn't surprise me. Chances are you'll have to find articles that tackle a specific audio topic, that can be applied to full range or multi way.
For instance. Maybe you'll find an article about audibility of off axis measurements in small and large rooms. You could look at the evidence and apply it to full range speakers, saying they have very regular off axis curves which the articles found the control group preferred.
Or the audibility of cone break up at various frequencies.
etc.
I think there's probably lots, just none of it has been applied directly to your topic. Lots of us here have done it, just not in a formal sense like you are trying to do. So if you come across something you think applies, feel free to bounce the idea off of us.
is that one of those situations that if you understand enough about how to parse your inquiry, you might already understand or intuit as much as the authors / experts on the subject?
It's one of those things where, if he's writting a research paper about the subject, he'll need to understand enough to know what to look for and how it may apply.
For instance, the cone break up example. If you don't know that there is some phenomenon called cone break up that many full rangers have to deal with, then you might not be able to tackle this subject. Because he'll gloss over any articles about it thinking it doesn't apply. But it doesn't mean he needs to understand what cone break up is, if it's audible, what makes it audible, what cone materials are conducive to break up, etc. The articles can tell him that.
Judging by his post #2 he's got a handle on the subjects that need to be looked into. There are many more though.
For instance, the cone break up example. If you don't know that there is some phenomenon called cone break up that many full rangers have to deal with, then you might not be able to tackle this subject. Because he'll gloss over any articles about it thinking it doesn't apply. But it doesn't mean he needs to understand what cone break up is, if it's audible, what makes it audible, what cone materials are conducive to break up, etc. The articles can tell him that.
Judging by his post #2 he's got a handle on the subjects that need to be looked into. There are many more though.
There isn't much research on the subject because there isn't much to research.
The audibility of resonances has been extensively studied and there is not much difference between multiway and single driver systems. Some full range driver exhibit more resonances than would be considered acceptable in a multiway.
Regarding being point-source v multiple sources, the ear cannot really tell unless the crossover is completely botched. Good phase overlap through the crossover region is all that is needed. Besides, the audibility of phase response errors has been extensively studied, and numerous researchers have found that minor phase errors, such as those in multiway systems, are inaudible.
The one thing that multiway systems may produce is lobing that will be not as bad in full range drivers. Here again, the audibility is questionable and it has been shown that smooth off-axis curves are preferred. Holes in the power response are ok, but peaks are not. Most full range drivers start beaming in the HF and off axis is quite chaotic. Multiway systems can maintain even off axis response over a larger range.
A good beginning point will be doing a blind test using a full range driver and comparing it to a multiway with identical on axis response. It may be hard to match the off-axis response, but it might be interesting to find out which is preferred even with different off-axis response. Maybe get some buddies and do a test at home? I would be interested in learning about the result of such a test.
If you haven't already read Toole, you definitely should. He has backed up everything he says with references that will help shorten your literature review.
The audibility of resonances has been extensively studied and there is not much difference between multiway and single driver systems. Some full range driver exhibit more resonances than would be considered acceptable in a multiway.
Regarding being point-source v multiple sources, the ear cannot really tell unless the crossover is completely botched. Good phase overlap through the crossover region is all that is needed. Besides, the audibility of phase response errors has been extensively studied, and numerous researchers have found that minor phase errors, such as those in multiway systems, are inaudible.
The one thing that multiway systems may produce is lobing that will be not as bad in full range drivers. Here again, the audibility is questionable and it has been shown that smooth off-axis curves are preferred. Holes in the power response are ok, but peaks are not. Most full range drivers start beaming in the HF and off axis is quite chaotic. Multiway systems can maintain even off axis response over a larger range.
A good beginning point will be doing a blind test using a full range driver and comparing it to a multiway with identical on axis response. It may be hard to match the off-axis response, but it might be interesting to find out which is preferred even with different off-axis response. Maybe get some buddies and do a test at home? I would be interested in learning about the result of such a test.
If you haven't already read Toole, you definitely should. He has backed up everything he says with references that will help shorten your literature review.
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So I went to sign up to the AES as a student member hoping to gain access to their E-Library. Their advertised price for student membership is $39/year (I can accept that for the knowledge I'll gain) - but it turns out that the E-Library costs another $145/year to access. Since my university already has access to everything but the E-Library I'm not about to spend $200/year for this special library card. They just lost a potential student membership due to their greed (Dave if you're a member you might want to convey this problem to the board).
ra7 - It's nice that you're offering suggested findings on the subject but I really do require substantiated references. I'm in the process of reading a few books by Mr. Toole. Is there one in particular you're thinking of?
tuxedocivic - I only have preliminary understanding of said topics at this moment. What other areas should be considered in this argument/comparison? Oh, and what's with all these locals commenting (I grew up in Nanaimo)?
ra7 - It's nice that you're offering suggested findings on the subject but I really do require substantiated references. I'm in the process of reading a few books by Mr. Toole. Is there one in particular you're thinking of?
tuxedocivic - I only have preliminary understanding of said topics at this moment. What other areas should be considered in this argument/comparison? Oh, and what's with all these locals commenting (I grew up in Nanaimo)?
Haha, ya, there's a few islanders kicking around these boards. Most much longer than I have.
Off the top of my head, I would consider research around the audibility of:
Off axis behaviour (vertical and horizontal) - most research says the off axis should be evenly spaced similar to the on axis;
Frequency extention - most research says the more extended (bass and treble) the more preferred;
Cone break up - yes, it's audible. But when, why, how much;
Passive cross over component value drift;
Phase - as pointed out most research shows this is of little consequence (not sure I agree);
Step response - the misalignment of driver's acoustic centres;
Intermodulation distortion;
Harmonic distortion.
I'm sure there are more. You might want to simplify your scope. To say "The common 6" woofer + 1" dome tweeter versus a 6" full range, both on a flat baffle simple shaped enclosure". You'll also find a lot of the research points towards multi-ways being superior. It'll be good to ask yourself why that is. See if you can make a case for full range. Maybe you should add an application to your scope, like "small rooms", "auditoriums", "mixing studio", or "nearfield".
It won't be easy
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms: Floyd Toole: 9780240520094: Amazon.com: Books
Buy it now. The references at the end run for about 35 pages, IIRC.
Most of Tux's questions above are answered in the book, such as resonances, phase, distortion. What's more important, and what the book focuses on, is finding out what we can hear and what simply does not matter.
This is nothing against full range drivers. Just that properly designed multiway has numerous advantages over a single driver. If you can get smooth, flat on-axis response and smooth off-axis curves, from a single driver over a wide bandwidth, it is even better. Just that it is physically impossible to do it.
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You might think about dividing full range into two subjects. Information may be different. The majority of full range drivers are extreme price sensitive: Cars, TV's, Boom boxes etc. The goals for range and quality are very different from the niche market this forum discusses where musicality, even at the expense of very limited range, limited levels and breakup issues are the primer concern. Sub $1 speakers made in the tens of thousands or more, vs. low production high fidelity. Both are difficult topics. I have to admit, I have never seen a paper on $1 speaker ( OEM cost) quality, only about more generic manufacturing process and quality. I suspect the work is done by the OEM's and never published. Seems a shame the biggest market is not served by research on performance as much as cost.
I can't cite references but it may be worth Googling the KEF/B&O Archimedes Project. It was more about room acoustics but led to the development of the KEF coincident driver, which may have some bearing. Here are 3 starter references:
Project - EUREKA
Enough Room? Sidebar | Stereophile.com
References
On the back of that, take a look at Dave Moulton's blogs about studio sound and the developments which led to the Beolab 9 loudspeaker:
Moulton Laboratories
Ted Jordan has written a lot about single driver speaker performance in the past - some of which deals specifically with cone breakup, cone flexing, etc. It tended to appear in Wireless World magazine or HiFi News but some of it is on his site at
E.J.Jordan Designs - book & articles design & consultancy
Chapter 5 of his latest Jordan manual is specifically about single cone drivers and that's available as a free PDF on the site.
Project - EUREKA
Enough Room? Sidebar | Stereophile.com
References
On the back of that, take a look at Dave Moulton's blogs about studio sound and the developments which led to the Beolab 9 loudspeaker:
Moulton Laboratories
Ted Jordan has written a lot about single driver speaker performance in the past - some of which deals specifically with cone breakup, cone flexing, etc. It tended to appear in Wireless World magazine or HiFi News but some of it is on his site at
E.J.Jordan Designs - book & articles design & consultancy
Chapter 5 of his latest Jordan manual is specifically about single cone drivers and that's available as a free PDF on the site.
So I finished my paper and had it marked so I can now post it here to get some seriously critical feedback (see attached pdf). I know it's not up to diyaudio standards of discussion, but it was only a first year paper in a general engineering class. I would honestly love to hear why I'm totally wrong or somewhat right, or ... it'll help me out in the long run.
Also, I don't know why I failed to see Colin's posting earlier, looks like some good starter research here that I managed to miss.
Also, I don't know why I failed to see Colin's posting earlier, looks like some good starter research here that I managed to miss.
You really need to get some personal experience with both "types" of speakers. With well designed and executed examples of each, the actual differences tend to be much less distinct than the forums and papers would lead one to believe. Many of the details debated ad nauseum in the forums are much less problematic to the ears and are usually overwhelmed by the room effects.
One issue that is generally minimized in this forum is that full range designs have some real performance limitations with several genres and preferences. Within their performance envelope, they can be wonderful, but that envelope is relatively limited. "FAST" designs are often used as a tool to expand the performance envelope and are tacitly treated as still "full range" when in fact you have now have a two way design.
Finally, this is not a zero sum game and there is no requirement for a unified field theory of speaker design. Personal preferences for music genre, spl levels, hearing differences, and so forth will dominate design types and details. Each side considers the other to be anathema, but realistically someone else's perferences really shouldn't matter to us.
One issue that is generally minimized in this forum is that full range designs have some real performance limitations with several genres and preferences. Within their performance envelope, they can be wonderful, but that envelope is relatively limited. "FAST" designs are often used as a tool to expand the performance envelope and are tacitly treated as still "full range" when in fact you have now have a two way design.
Finally, this is not a zero sum game and there is no requirement for a unified field theory of speaker design. Personal preferences for music genre, spl levels, hearing differences, and so forth will dominate design types and details. Each side considers the other to be anathema, but realistically someone else's perferences really shouldn't matter to us.
Hi Stochastic.
I'd like to comment on your paper. I'm an engineer myself and probably would have written this paper at about the same level as you have in my first year. I won't comment to much about the technical details, as it won't help your engineering career very much, only your diyaudio hobby. The tech details were mostly correct IMO, although perhaps not the strongest technical points for making the case.
I must ask, did you write an outline for this paper? And how detailed was it? When I read the paper the thoughts are a bit unorganized and hint at having been written as the research was carried out. This is a common temptation. It's important that you document the research, put it in an outline, scrutinize that, adjust, write your introduction, write your conclusion, re-write your outline, then begin. If you did write an outline, perhaps spend more time on it next time. The time spent writing an outline has never been wasted for me. I write a reports every week as part of my career and still skip the outline often (so I'm a hypocrite, sue me), but when I do use them, my report is always better and saves me editing time and my reviewer is always much happier saving more time.
Next, I really hoped to see some figures or diagrams. You threw in a lot of technical detail that would mean nothing to a lay person. Even a hifi enthusiast. Some frequency responses showing come breakup, cross overs, even a photo of a typical 2-way and a full range. This would have added a whole level of clarity to your writing.
This relates to the outline idea, but break up your thoughts. Even if you had sections in the report, like section 1: Definitions or multi way and full range. Then discuss that topic, and not anything else. When you discuss a topic, make sure it's focused. You wrote this like a letter to the editor rather than a technical report. Make bullet lists, headings, tables, whatever helps organize the writing to focus on the final knockout conclusion.
Finally, link your conclusion to your research. So why are full range better? When I got to the conclusion I thought "oh we're here already, ok so multiways are better or what??". You had a lot of info, but it didn't form a conclusion.
I hope this helps. Engineering writing is a royal pain. I still struggle with it. In high school they teach you to write an English essay, then you get to engineering school and that MUST go out the window. If you ever want something reviewed or proof read, send me a pm.
I'd like to comment on your paper. I'm an engineer myself and probably would have written this paper at about the same level as you have in my first year. I won't comment to much about the technical details, as it won't help your engineering career very much, only your diyaudio hobby. The tech details were mostly correct IMO, although perhaps not the strongest technical points for making the case.
I must ask, did you write an outline for this paper? And how detailed was it? When I read the paper the thoughts are a bit unorganized and hint at having been written as the research was carried out. This is a common temptation. It's important that you document the research, put it in an outline, scrutinize that, adjust, write your introduction, write your conclusion, re-write your outline, then begin. If you did write an outline, perhaps spend more time on it next time. The time spent writing an outline has never been wasted for me. I write a reports every week as part of my career and still skip the outline often (so I'm a hypocrite, sue me), but when I do use them, my report is always better and saves me editing time and my reviewer is always much happier saving more time.
Next, I really hoped to see some figures or diagrams. You threw in a lot of technical detail that would mean nothing to a lay person. Even a hifi enthusiast. Some frequency responses showing come breakup, cross overs, even a photo of a typical 2-way and a full range. This would have added a whole level of clarity to your writing.
This relates to the outline idea, but break up your thoughts. Even if you had sections in the report, like section 1: Definitions or multi way and full range. Then discuss that topic, and not anything else. When you discuss a topic, make sure it's focused. You wrote this like a letter to the editor rather than a technical report. Make bullet lists, headings, tables, whatever helps organize the writing to focus on the final knockout conclusion.
Finally, link your conclusion to your research. So why are full range better? When I got to the conclusion I thought "oh we're here already, ok so multiways are better or what??". You had a lot of info, but it didn't form a conclusion.
I hope this helps. Engineering writing is a royal pain. I still struggle with it. In high school they teach you to write an English essay, then you get to engineering school and that MUST go out the window. If you ever want something reviewed or proof read, send me a pm.
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