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Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (Audio Engineering Society Presents)?
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Sort of. You're combining at least three separate concepts.
1) Speaker Boundary Interference (SBIR) - above a frequency proportional to the distance to the rear wall, the reflection will interfere with the direct sound. Shorter distances affect higher frequencies that tend to be more directional and not seen by the wall anyways.
2) Boundary gain - below a frequency, the rear wall reinforces (~+6dB) the bass response of the speaker. This can be shelved down in DSP to mitigate. The owner of the system pictured does so.
3) Port vent - the tuned port extends the response of the system but a wall won't affect it that much. The rule of thumb is a distance of 1-2x the port diameter from the wall to not change the port performance.
The reason why ports and wall placement often come up together is because boundary gain can be offset by plugging the port.
Also, this system belongs to Dr. Floyd Toole who was the VP of research for Harman. They literally wrote the book on sound reproduction.
Is the placement ideal? Not really. Does Reddit know better? Not really.
In their book, they describe a few of the steps that they took to mitigate some of the problems that I listed above. Maintaining livable space was more important than the small hifi improvements.
> My own interpretation of the data probably won't be very good at this point, but if his stuff is consistent, it'll hopefully be a useful source to learn from.
For really learning about speakers, I'd refer you to this book as it's based on research by Floyd Toole. For those that value objective measurements his research is effectively the gospel as he basically built the standard at NRC and Harman.
Other than that there's a lot of independent research one can do. Reading back into Sean Olive's blog (picked up Floyd's torch), and videos/presentations by them and Andrew Jones (leans engineering oriented).
Those are going to be some of the loudest voices when it comes to measurements, their usefulness, shortcomings if applicable, etc.
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms
Harman has done a lot of speaker preference testing. The testers performed worse with multi channel and "discontinuous and narrow band signals". Note that these are double blind critical listening tests. Testers are completely focused on the sound. Add a picture and story to the mix, and I think the differences will be even less.
That makes sense. Control rooms tend to actually be treated.
If a control room has 10dB of room gain, I'd say it really needs acoustic treatment. Years ago when LEDE was very popular, getting rid of everything that isn't the direct sound was the goal. It's not unreasonable to end up with a nearly dead room in that case.
The paper is dense but it's practically become the Bible for residential listening rooms. Certainly worth the read, in my opinion. It's a compliment to his book Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms which expands on it quite a bit.
From a technical standpoint no, you're just choosing which lower bass frequencies go to which speaker. Theoretically speaking it shouldn't sound any different at lower volumes when you change the setting.
However there's a shit ton of variables that effect the sound you hear. Room reflections from floor/ceiling/walls, boundary gain from being near a wall, SBIR which is cancellation based on distance to wall, room modes for your speakers, room modes for your subwoofers, target curve of AVR, quality of AVRs room correction, frequency response of subwoofer/main speaker, which seat within the room your sitting. All those will effect your bass response in your room. If you're interested in understanding more about those definitely do some research it's too complex of a thing to explain all of them without writing a 20 page novel. Home theater gurus on YouTube talks a lot about them. Audioholics has some good webinars on YouTube with Anthony Grimony. Or best yet this book which would give you an indepth understanding which would surpass my knowledge.
So depending on how each of those variables effects the sound you could have a boost or dip in bass at a specific frequency which would if you include or exclude it via your crossover could increase or decrease the bass you hear so the more it increases the overall balance of the speaker would be effected.
Tldr: it could go either way. As always it depends hence why calibrated microphone or doing a lot research to gain an advanced understanding of acoustics.
I highly recommend the book "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (Audio Engineering Society Presents) 3rd Edition" by Floyd E. Toole.
The author does a good job of explaining (among other things) how/why humans are pretty bad at removing bias when listening/reviewing audio gear. He focuses on speakers, but a lot of it extends to other pieces of audio gear as well. In his many (many...as in decades worth) of tests, both in simulated living spaces (designed to replicate a living room) and in anechoic listening chambers, he found that listeners were pretty good at picking out good vs bad (or, good vs less good) speakers in blind tests and they almost always align with technical measurements. There were, however differences between trained critical listeners (the best), musicians (somewhere in the middle), and laypersons, but all groups do relatively well.
But as soon as one or more of the products are known, the results skew wildly. If you know what you're listening to, you're going to have bias. There's no escaping it, no matter how "good" you think you might be at critical listening. The author is very critical of the majority of audiophile reviews for this very reason.
https://www.amazon.com/dp/113892136X?psc=1&ref=ppx\_yo2\_dt\_b\_product\_details
> Who is we? lol
Floyd Toole wrote the book on loudspeaker design (literally wrote the book).
It has been generally accepted as the de-facto standard.
If you're a representative, or authorized dealer for a brand like Denon as an example you go through a pretty extension training suite(either in person or on-line) for pretty much any product you may sell. Then they send you updates to that annually and sometimes more frequently if there's been something introduced that they feel you should be required to "certify" on to best represent their brand.
But, otherwise, it's a lot of hands on experience combined with researching things online or in books(anyone remember those?)..:)
For example, goto you tube and search for "floyd toole" or even better grab his new book at amazon.
https://www.amazon.com/Sound-Reproduction-Psychoacoustics-Loudspeakers-Engineering/dp/113892136X
Other than the above I would guess most professionals just try to share their general knowledge as time allows and usually stick to their respective fields. A television engineer might not be very active in a subwoofer forum for example..:)
Well, measurements like directivity and estimated room response are very good indicators of the sound of a speaker. For example Audioholics has made quite a few articles trying to explain that to people. Of course the Dr. Floyd Toole’s book and all other research he has been part of are perhaps the most known research of that.
Because with off-axis measurements you know the radiation pattern of each driver.
This allows you to blend the drivers in such a way that it maintains a consistent radiation pattern, leading to a speaker with slowly declining sound power (total radiated energy). Combined with a flat on-axis response, this results in a good quality speaker which people enjoy. This is based on research conducted by Floyd Toole and Sean Olive, with published AES papers. Here is a talk by Floyd Toole, and a Sean Olive interview which covers this. Also Floyd Toole has a book about it.
https://www.youtube.com/watch?v=zrpUDuUtxPM
https://www.youtube.com/watch?v=IEtYH03pfOI
You might compromise the radiation pattern for the sake of power handling. For example, you cannot realistically crossover a 1" dome tweeter at 1000Hz, even with a 4th order slope. The speaker wouldn't be able to play loudly without audibly distorting, even though the radiation pattern of the finished product would look better than using a 2000Hz crossover.
Z offset is a somewhat misunderstood topic in speaker design. Lets say you are using a dome tweeter with no waveguide, so the acoustic centre of the tweeter is further forward than the woofer acoustic centre. This is going to cause a time arrival difference, and applying a Z offset does not eliminate that difference. What it does is move the anomaly in the vertical radiation pattern. Is this an audible problem, well it depends on how big the offset is. You still hear the offset because of the reflections off your ceiling and floor, but it might not be noticeable.
To explain things in practical terms, it may help to look at the data collected from an optimized speaker.
https://www.audiosciencereview.com/forum/index.php?threads/kef-r3-speaker-review.12021/
The on-axis is obviously quite flat, but you will notice the early reflections, and sound power decline smoothly. This is because the tweeter and mid-range driver are a coaxial arrangement. Meaning the time arrival is perfectly aligned regardless of orientation, and the mid-range cone acts a waveguide for the tweeter, aligning the radiation pattern in the crossover region of 3000Hz. The woofer is crossed at 400Hz, low enough that it barely disturbs the radiation pattern.
This leads to the speaker having a preference score of 8.1 when used with good quality subwoofers, one of the highest for any passive loudspeaker. This score comes from a formula derived from the speaker research done at Harman. It isn't infallible, but a good starting point when designing a speaker.
https://patents.google.com/patent/US20050195982A1/en
Particularly, there is some debate over wide and narrow radiation patterns. For example, trading spaciousness vs imaging precision, due to the different level of room reflections. Here is an example of a well designed 2 way horn loaded speaker. While the on-axis has problems, the sound power is excellent, meaning that with EQ to correct the on-axis, it would become an excellent speaker.
https://www.erinsaudiocorner.com/loudspeakers/diysg_htm12v2/
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms - really amazing book, I'm on my second read-through.
THE ABSOLUTE SOUND - Illustrated History of High-End Audio - note that there are two parts
Master Handbook of Acoustics - This genre of of books shouldn't be too hard to find at the library.
Many more resources on https://www.reddit.com/r/audiophile/wiki/guide
Floyd E. Toole
https://www.amazon.com/Sound-Reproduction-Psychoacoustics-Loudspeakers-Engineering/dp/113892136X
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You might also have a look here: https://www.audiosciencereview.com/forum/index.php?forums/audio-reference-library.30/
When you’re ready, this book covers most of the basics of speaker design
I think that book is a great place to start, Floyd Toole also did a 1 hour presentation which sum up the key points.
https://www.youtube.com/watch?v=zrpUDuUtxPM
For people looking to actually build speakers, I usually start with these two:
https://www.parts-express.com/Loudspeaker-Design-Cookbook-7th-Edition-Book-500-035
https://www.amazon.com/High-Performance-Loudspeakers-Optimising-Loudspeaker/dp/1118413539
When it comes to sound, modern research show us that the natural human preference is for a flat on-axis sound, with off-axis sound that gradually declines in volume, ideally tracking the on-axis. When such speakers are placed in a typical room, they create a frequency response which has a slight downward trend, meaning the bass is prominent, while treble is tapered off. There is variance between casual and experienced listeners, but everyone follows the same trend line.
Horn loading is a method to improve the impedance matching of a compression driver. When a raw driver is used, the efficiency is poor, because only the air molecules directly in front of the driver are coupled to the pressure wave being created. With a horn, more force can be exerted for the same input power, while at the same time controlling the directivity (off-axis response). You can use horn loading for woofers and mid-range drivers as well, but the sizing becomes problematic for residential use.
If you have other questions, feel free to make a post in /r/diyaudio or /r/diysound and tag me with /u/DZCreeper, I can answer most questions or point you at good resources.
>I would like to learn more about audio and headphones, what sources would you recommend to learn about this topic ?
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms by Floyd E. Toole.
Loudspeaker and Headphone Handbook by John Borwick.
Headphone Fundamentals and Comparison with Loudspeakers by Carl Poldy.
Thanks for the reference- this book is new to me. I poked around a bit and found the 3rd edition is available on Amazon ($53).
It’s considered a textbook, and there’s a companion website with some free content about “Designing a Home Theater” and “Sound Isolation”.
Floyd Toole has done just about every role at some point.
https://www.amazon.com/Sound-Reproduction-Psychoacoustics-Loudspeakers-Engineering/dp/113892136X
​
https://www.audiosciencereview.com/forum/index.php?threads/a-chat-with-dr-floyd-toole.23347/
I am going to be the asshole. Your design is full of flaws, just like my first design was. Read a book on speaker design, and start making good speakers.
Loudspeaker Design Cookbook by Vance Dickason is good.
https://www.parts-express.com/Loudspeaker-Design-Cookbook-7th-Edition-Book-500-035
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms by Floyd Toole is solid supplementary material.
Your drivers should be as close together as possible. This optimizes your off-axis response, meaning you get a more consistent sound at multiple seats, and also less problematic room reflections. Especially your mid-range and tweeter.
Baffle edges should be rounded. This reduces edge diffraction, which causes peaks and dips in the frequency response.
Your port tuning absolutely matters. You need to use the T/S parameters of your woofers in order to design the optimal cabinet with a program like WinISD. If you tune too high, you get peaky bass that only hits hard at one frequency. If you tune too low, you get saddle shaped bass which sounds weak. Some drivers are outright suited to sealed cabinets.
The impedance of the drivers has nothing to do with how well they work together. It all comes down to crossover tuning. Crossovers are not something you buy off the shelf, they are the heart and soul of the speaker. Cheap drivers can work miracles with a good crossover designer, expensive drivers can sound bad if you don't put in the work.
Why do off the shelf crossovers sound bad? They make dumb assumptions like the drivers have a flat impedance curve, and give no consideration for the off-axis response of the speaker. Anybody can design a speaker which is flat on-axis, and still sounds like crap. The radiation pattern of each driver needs to blend into the next.
I make this whole speech pretty often, I don't mean to discourage you. Speaker design is a complex science, feel free to ask questions either in this thread or message me directly.
The best resource I could recommend is getting a degree in Physics and Electronics. That's what I did.
If you want to study on your own, these books were recommended to me by oratory1990 and other folks who actually specialize in the field of acoustics. I have them both, they're great.
https://www.amazon.com/Sound-Reproduction-Psychoacoustics-Loudspeakers-Engineering/dp/113892136X/
https://www.amazon.com/Loudspeaker-Headphone-Handbook-Third-Borwick/dp/0240515781/
I would also add Sound Reproduction by Floyd Toole: https://www.amazon.com/Sound-Reproduction-Psychoacoustics-Loudspeakers-Engineering/dp/113892136X/
I don't need to hear them, that's pretty much the point. The only good thing about the RP-600M is that the off-axis performance follows the on-axis so you can equalize it pretty easily to sound good. I can recommend this book: https://www.amazon.com/Sound-Reproduction-Psychoacoustics-Loudspeakers-Engineering-dp-113892136X/dp/113892136X/
It handles loudspeaker preference based on objective measurement data in one of the chapters.
> After much contemplation, wonder and imbibing of beverages, I return to thank you.
You should save the contemplation and beverages for when you get the eargear - it's a common witticism among audiophiles that the best upgrade to your system is a higher BAC :P
>On the contrary, this is fascinating! I'm in science writing (nonfiction and fiction), so I get to appreciate this kind of nerdery. It kind of answers this hazy question I have about why does good audio equipment cost so much. We're still sciencing it out, which is cool. I mean, that goes for most technology, so it's not unique, but for me, it's a whole new world.
If you like that, Sean Olive, a fairly major person in most of the above links, has an infrequently-updated but occasionally pretty neat blog, and on the heavier end of things his mentor Floyd Toole has a wonderfully detailed and IMO shockingly readable text on sound from a music/listening standpoint.
I will say, while there's definitely a component of development/progress being funded here - particularly in headphones, an area which has been seeing both a vast increase in prices and a substantial rise in quality over the past decade or so - I'd also point to two other factors driving high audio equipment prices:
The first is that, in many respects, audio tech develops exceptionally slowly - there were condenser microphones and electrostatic headphones made in the 1960s and 70s that are in many respects comparable to modern high-end equipment, and we haven't got that much more efficient at making them either. Unlike, say, integrated circuits, the core mechanisms of electroacoustic transducers haven't really become smaller, more efficient to make, or higher performance, at least to nearly the same extent, nor have we developed many alternative methodologies - we have better diaphragm materials, stronger magnets, and better assembly processes than in 1920 or 1970, but not to nearly the extent of, say, transistor or capacitor manufacturing, and almost all headphones, speakers, and prior to the smartphone revolution microphones are still the same style of moving coil design that existed at the start of WWI.
This, to some degree, keeps our buying power a bit low compared to what we're used to - I can get a 1980s supercomputer in my pocket for $100, but it's not that much cheaper to make a high-quality headphone now than it was then (and, indeed, some high-end headphones from that era that have persisted since then - Stax's Lambda series, for example, and Beyerdynamic's DT880 - have seen their prices track with inflation for the most part, or in some cases rise).
Of course, I'm neglecting the increasing use of modern technology in some bits of audio tech - digital signal processing, in particular, has immense potential, and has yielded exceptional results in many cases - but that's partially because the field of high-fidelity audio has been comparatively slow to adopt things like digitally controlled speakers and headphones, and where they do exist they tend to in fact be closer to the commodity end of the price range than the high end (and, sadly, they often underperform their potential as a result of this lack of attention).
The second is that the higher end of audio equipment primarily consists of Veblen goods - while there are many fine speakers, headphones, amplifiers, and so on available at higher price tags, for decades the highest end of the hobby has been defined at least as much by luxury and status as by actual technical performance. This isn't really that pertinent in the price ranges that sane people talk about - a $100-400 headphone or speaker definitely has some status signalling component for its buyer, but it also just plain costs money to make these things, and often as you climb past the "sold in gas stations" price bracket you see massively diminishing sales volumes, with the attendant loss of economies of scale. That said, outside of "lifestyle/consumer" products, a lot of the field is driven by the eccentricities of the higher end, and when that segment isn't looking for cost reduction (or, in fact, may be looking for the opposite), it has some weird impacts on how resources are allocated and what sorts of products are developed, even outside of the realm of $10k/meter cabling and $200k per pair speakers.
Erm, sorry to ramble at you, but I'm really into this stuff, and sometimes I get carried away.
>Makes sense. Would my unrefined taste buds really appreciate a $1,000 bottle of wine over a $30 one? Probably not.
Oenophiles are a common comparison point with high-end audio, as a matter of fact - although usually from the standpoint of "past a certain point, you aren't really getting more quality" rather than "your palate isn't refined enough" in my experience.
> I have no idea what this means but it got me searching how do brains process sound, good stuff.
It's a really fascinating topic, although I'm mostly hip to the parts that are pertinent to headphone design (my profession) more than the neurological (or physiological in general) side of things - in general, once you get to the eardrum, my job is pretty much done. A lot of weird stuff happens by that point, however - you can spend a fair while just getting your head around how the binaural hearing apparatus lets us locate sounds in three dimensions.
> I think I want a better sound experience, and it's worth it in my situation to invest better in both speakers and headphones. I've actually decided to downgrade to the 3700x build in order to grab better eargear.
I hope that it ends up being worth your while! I'll be interested to hear your thoughts on the gear, if you have any.
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