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PostPosted: Mon Jul 02, 2018 11:38 pm 
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Location: Arnhem, The Netherlands
Hi people!

I've recently discovered this forum. It seems to be a vault of knowledge, which I'll try to take in as best as I can.
A short introduction.
I'm The Sound Guy from Arnhem, the Netherlands. I work as a recording- and mix engineer, also do live sound FOH jobs. In my (not so spare) room in my home, I'm trying to build a room that's suitable for mixing and an occasional overdub.
Right now I have a 2.1 monitor set. The sattelites have limited low-end output. -3dB is said to be @40Hz, but 55Hz is a much more realistic number. There's a definite roll off starting below 80Hz. To help the bass, I use an Adam Sub 10mkII crossing over at 65Hz, running the sattelites full range.

Currently, I can make mixes that sound good, but not as good as I'd like. They travel reasonably well to a high end hifi 2.2 system in my living room and also to my car. There are no big balance issues on either system, except perhaps some problems in the low bass range (which is to be expected). I want my mixes to sound better overall. In an effort to examine where I can gain skills, I've found the biggest problem to be the acoustics of my room. Bass is difficult, but I've come to believe that the mid-range balance and clarity are also greatly compromised by my acoustics.

I do mainly pop, rock and jazz work. I rarely, if ever, mix louder than 85dB. It concerns a home in a residential area. Right below this room are neighbours, as are right next to the room.

My room measures 463cm (L) by 298(W) by 240(H). There is a door 65cm from the corner in one of the long walls. There is a window off-centre in one of the short walls. See attached picture. Below the window is a heater.
The room is partly shoe-storage for my girlfriend's shoes. Is has a few Swedish book cases (Billy, 4x and Besta 2x). Those hold my movie collection, paperwork, files, invoices, books, magazines, software (on cd!!), printer, audio-interface, amplifier and other stuff. Though I may be able to clear and delete some of that, the room will need to have at least a number of bookcases for storage purposes. The room also contains a couch that sometimes doubles as an extra bed.

Now, as I've gathered from the Amroc simulation, the room's dimensions are far from ideal, lying outside the Bolt area.The Bonello curve isn't evenly spread, as well (1-0-2-...). The first room mode occurs at 37,4Hz, which will be hard to tame.

Looking at both the Amroc simulation and the floor plan, what can be said about attempting to sort out the acoustic problems of this room - knowing there are limits to how much I can move things around in there..? Will this be feasable to some extent? Or is it going to be hopeless?
Willing to do bass trapping, cloud, broad band absorption, diffusion, whatever it needs. Preferably DIY, since that's the most fun! (:

I plan on doing some measurements some time soon, when I can find enough time. I have a spare pc running Arta, which uses a Dayton EMM6 measurement microphone. Can this be used, or must it be REW?

Anything else you need to know?

Thanks!

TSG.


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PostPosted: Tue Jul 03, 2018 3:43 am 
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Hi there "TSG", and welcome! :)

Quote:
I've recently discovered this forum. It seems to be a vault of knowledge,
We think so too! Thanks for the kind words.

Quote:
Right now I have a 2.1 monitor set. The sattelites have limited low-end output. -3dB is said to be @40Hz,
Make and model?

Quote:
There's a definite roll off starting below 80Hz. To help the bass, I use an Adam Sub 10mkII crossing over at 65Hz, running the sattelites full range.
IT would be better to run the satellites through the sub, and let the sub take care of the cross over. I would also suggest setting the cross-over higher than that: more common would be 80 Hz or so. In the range 70 to 90, anyway.

Quote:
There are no big balance issues on either system, except perhaps some problems in the low bass range (which is to be expected).
Ahhh, but that's the thing! If your room was telling you the truth, and meeting ITU BS.1116-3 specs, then there should be NO problems in the bass range... :) So the question is: how close can we get your room to meeting the specs?

Quote:
I've found the biggest problem to be the acoustics of my room. Bass is difficult, but I've come to believe that the mid-range balance and clarity are also greatly compromised by my acoustics.
Very likely. In an untreated or poorly treated room, the entire spectrum suffers.

Quote:
I rarely, if ever, mix louder than 85dB. It concerns a home in a residential area. Right below this room are neighbours, as are right next to the room
Do you currently have problems with isolation? Complaints from the neighbours? Or problems with sounds from outside your room disturbing your mixing sessions?

Quote:
My room measures 463cm (L) by 298(W) by 240(H).
So roughly 13.8 m2, and 33 m3. That's small. The minimum recommended size is 20m2 and 47 m3. That does not mean that it is impossible to use your room. IT just means that it is going to need a lot of treatment, and it won't be possible to fully meet BS.1116-3.

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See attached picture.
From the diagram, it seems that you have the room set up backwards! It would be better to rotate it 180°, to face the other way, That would give you better symmetry, and better treatment options.

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The room is partly shoe-storage for my girlfriend's shoes. Is has a few Swedish book cases (Billy, 4x and Besta 2x). Those hold my movie collection, paperwork, files, invoices, books, magazines, software (on cd!!), printer, audio-interface, amplifier and other stuff. Though I may be able to clear and delete some of that, the room will need to have at least a number of bookcases for storage purposes.
Then I have some bad news for you! Unless you strip out everything, it is never going to meet BS.1116-3, nor even get close. All of those things are messing up the acoustic response of the room, very probably in the mid range, and they are also occupying the wall space where you will need to install acoustic treatment.
Quote:
The room also contains a couch that sometimes doubles as an extra bed.
That's fine. No problem. As long as it is at the back of the room (opposite end from the speakers / desk).

Quote:
The first room mode occurs at 37,4Hz, which will be hard to tame.
Yes it will, but you don't know if it is being triggered or not, nor to what extent, and you also don't know if any of the other potential modal issues are being triggered or not, nor their severity. Simulation is one thing, and it is useful, but actual testing is an entirely different thing: it tells you how the room is ACTUALLY behaving, in real life. You should run a test in your room. Here's how: viewtopic.php?f=3&t=21122 .

Quote:
Will this be feasable to some extent? Or is it going to be hopeless?
Feasible to some extent, but with limitations. There are two sources of limitations here: 1) the size of the room itself, and you can't do much about that (unless you feel like knocking down walls!) and 2) The self-imposed ADDTIONAL limitations from not clearing out the room fully, down to bare walls. You CAN do something about that...

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Willing to do bass trapping, cloud, broad band absorption, diffusion, whatever it needs.
The room is definitely too small for most forms of diffusion, so you are stuck with absorption, mostly.

Quote:
Preferably DIY, since that's the most fun! (:
:thu:

Quote:
I plan on doing some measurements some time soon, when I can find enough time. I have a spare pc running Arta, which uses a Dayton EMM6 measurement microphone. Can this be used, or must it be REW?
If you have a PC and an EMM6, then why would you not want to run REW? It is FREE, and is one of the best acoustic packages out there! I never figured out why the author still wants to give it away for nothing, when it totally beats some of the other packages that cost a lot of money. Most people on the forum use REW because it is fantastic, free, widely used, and standardized. If you use some other software, then chances are you won't find many people to help you analyze the results. The only hope would if your "other" software is able to run an accurate test of the room, then export the results in a form that REW can import, such as a true impulse-response file.

- Stuart -

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PostPosted: Wed Jul 04, 2018 12:26 am 
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Hi Stuart,

Thanks for your elaborate reply!
Indeed, there are some restrictions. Self imposed and otherwise. I’m going to clear out the room as best as I can. It’s about time I cleared out some old junk, any way and re-organize. It’s still the only spare room I have in the house, so I fear it will be impossible to turn the room into studio-only. For now, I suppose I’ll have to be satisfied with however good it can get. Which will be a lot better than it is now, I’m sure!

I have had no troubles with my neighbours. They’re quite understanding and I have good relations with them. Street noise is somewhat of an issue, but not as big a deal as I would have expected. Some outside noise can be benefical, any way. I’ve found it sometimes helps me judge intelligibility. If I can still understand the singer, follow bass lines or hear guitars with street noise, the mix is good.

About the monitors: they are a set of Dutch-built Studio de Schop “Climax”, first version. About 30 years old. 4 – 5 liter reflex cabinet, 6.5” Vifa C17 woofer, 19mm Vifa D19 tweeter. First order slope on the woofer, second order on the tweeter. They’re nothing spectacular, but still surprisingly good. They’re driven by a Quad 520f power amp.
Recently I replaced the dried and rotten woofer surrounds. At the same time I upgraded the cross-over parts for much better quality parts of the same value and I’ve added some additional damping (10mm felt along the side walls and top/bottom – there already was some foam behind the woofer). It all resulted in a “better” sounding speaker: the same character, but with more finesse, slightly more detail in the treble and more clarity in de mid-range. Of course, I’m listening near field in compromised acoustics, I now realize. So I probably haven’t yet heard what these speakers really sound like…

I know it’s “normal” to have a sub cover the spectrum up to about 80 – 100Hz. However, and I’ve come to this realization more than once, I somehow prefer the sound if the sub does as little as possible. That also helps integration with the mains, is my experience.
That’s the case here, too. I’ve tried running the sub higher, but it becomes boomy very quickly. Moving it around the room doesn’t really improve things (in this acoustics..? duh..!). This position and set-up seems to work best for now. Translation to other systems is not *that* bad… So I’ll take that as proof that the current set-up works as well as it can. But of course, I want it to be better.

Why would rotating the room 180 degrees help? Because I’m no longer facing the window and can symmetrically treat the (new) front wall?

I have a pc and an EMM6. It’s not that I don’t want to use REW, I just have something similar at hand. I’ll look into it! If it’s free, it’s good (Hey... I'm Dutch..! :mrgreen: ) ;-)


Last edited by The Sound Guy on Thu Jul 05, 2018 12:00 am, edited 2 times in total.

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PostPosted: Wed Jul 04, 2018 5:19 pm 
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Soundman2020 wrote:
When I design studios, I never start by looking at the empty room and deciding what speakers might be good or not good: that would be silly. Instead, I start with the question: "What speakers does the customer need for doing the job that he needs to do?" Based on the best speaker that will do the job, I then design the room around those speakers. Doing it any other way would be short-sighted.

The above is what I read in another thread.
This gets me thinking...
I'm in the market for different/better monitor speakers. Preferably with greater bass-extension to at least just below 40Hz. But since my room in it's current form has big bass problems, should I be aiming for something smaller? When mixing (or just recreational listening) I really like to hear and judge the entire spectrum, all the way down to 20Hz.
I somehow think that concentric designs (Tannoy, Equator, ...) would be good, because they're true point sources by design. And, because it's a sort of horn, it has the benefit of having very good directivity and focus / clarity. I like the Tannoy sound, but I'm also a huuuuge Dynaudio nut. I really dig their design philosophy and sound. So, DMT6, System600, or Equator D5 seem like good candidates for concentric designs. Dynaudio BM5/6, LYD5/7. Of course there are boat loads of other good and suitable speakers out there. I can add my sub later. Or buy/build a better one. Or, if that's preferable acoustically, look for a single full-range (three way?) system with extension into the low 30's/high 20's. I have a pair of original Auratone 5's for a second reference.

1) Should I measure my room in it's current form, with my current speaker/sub set-up?
2) Should I first re-orient and re-organize my room before meauring with my current speaker/sub set-up?
3) Should I first re-orient and re-organize my room AND install different monitors before measuring?
4) How I can sensibly judge which monitors I want to use in my room, if the current acoustics suck?

Can somebody shed some light on this?


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PostPosted: Thu Jul 05, 2018 2:37 am 
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I'm in the market for different/better monitor speakers. Preferably with greater bass-extension to at least just below 40Hz. But since my room in it's current form has big bass problems, should I be aiming for something smaller? When mixing (or just recreational listening) I really like to hear and judge the entire spectrum, all the way down to 20Hz.
There really isn't much that goes on down at 20 Hz. Nor 30 Hz either. The ONLY instrument that gets down to 20, is the cathedral pipe organ. A very big one. The harp, tuba, and contra-bassoon can get down to the low 30's, but typical rock/pop/jazz/etc band instruments only start at around 35 Hz, give or take. The six-string bass played open can get down to 31 (B0), but there's no much music that actually calls for that. The drum kit starts around 40-something for large floor-toms and kick tuned low, bot more commonly in the 60's and 70's with toms and snares rather higher (snares are usually in the 200s and 300s.

OK, so that's the reality of what typical instruments do: so now you need to decide what type of music you typically mix. If you do a lot of church organ stuff, with contra-bassons, harps and tubas, then you'd need speakers that go down very low: very large subs, (several of them), and some pretty hefty bass trapping and SBIR treatment. On the other hand, if you only normally track and mix female soprano vocals and banjos, then a pair of small 6" mains would do fine, since you wouldn't be dealing with anything under about 100 Hz. On the other-other-other hand, if you do Foley or effects for movies, such as canon fire, volcanoes, planets colliding, earthquakes, and things like that, then you'd need a setup that goes even LOWER than 20 Hz, because you'd be getting into infrasonics, vibrations, and things that we humans can0t hear but can still sense with out bodies, and which some modern movie houses do actually implement. OR if you do a lot of work for clubs, discos, and suchlike, then that's heading down into the region of church organs as well.

That's why I said in that comment you quoted that I look at what the customer NEEDS for HIS situation, and find speakers that will effortlessly do what he wants, plus a bit more. You need a sound system that can faithfully and accurately reproduce the sound spectrum that YOU need to deal with, then you need to set it up so that it can do that optimally, given the dimensions and overall acoustics of the room, and finally you need to treat the room acoustically to get all of that under control, so that you have smooth, even, flat frequency response and time-domain response.

So it's unlikely that you need a system that goes down to 20 Hz, but for typical contemporary music, you probably do need to get down well below 50, and very likely below 40.

But here's the issue: Let's say for argument's sake you decide that the lowest stuff you need to hear is around 40 Hz, so you pick a speaker whose specs say it can hit 40Hz at -3 dB. Well, that's not good enough! If it is hitting 40 Hz at - 3dB, it STRUGGLING! It's is not doing it "effortlessly". It is at the limit of its capabilities, and is working really hard to do that. In fact, in all likelihood the designer used a few "tricks" to force the speaker to go that low, so it really isn0t doing it very well. My rule of thumb is that you should aim for a speaker that goes a quarter to a half an octave lower than where you need to go. So if you have a really need to mix stuff at 40, then you should be looking for a system that can hit 30 Hz at -3dB, and certainly nothing rated higher than 35 Hz -3dB.

Think of it this way: if you were going to buy a car, and needed one that can cruise at 80 MPH with 6 adults and 4 suitcases going on a thousand-mile trip then you would NOT look for one that has exactly 6 seats, a top speed of exactly 80 MPH, and space for exactly 4 suitcases! Rather, you'd look for one that has a top speed of around 120 MPH, seats 8, and has space for 6 o more suitcases. Because even though the first one would theoretically do the job, it would be screaming its guts out to cruise at 80, it would be very uncomfortable ride because the suspension would be maxed out all the time, and it would be cramped and claustrophobic, with no place to even put in a few bottles of coke and a couple of pizzas!

So don't under-sell yourself on the speaker. The same principle applies here: get speakers that can do what you need them to do, comfortably, without straining.

Quote:
concentric designs (Tannoy, Equator, ...) would be good, because they're true point sources by design.
True, theoretically, but in most studios it's not too much of a practical need, since you are usually seated far enough away from the speaker that the various fields form the various drivers and ports have fully merged. As long as you are further away than what the manufacturer recommends as the minimum distance, the "point source" argument is somewhat of a moot point. And if the drivers are arranged vertically, then it's even less of an issue, because our human hearing apparatus doesn't have the ability to determine directionality very well in the vertical plane: only the horizontal plane.

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because it's a sort of horn, it has the benefit of having very good directivity and focus
Are you sure you want that? And it's not really a valid point anyway: pretty much all studio reference monitors that I'm aware of have very carefully engineered horns on the tweeter: If they didn't the impedance mismatch between the cone and the air would create very poor frequency response, and the thing would sound pretty ugly. It's a myth that you should get a speaker that "focuses" the sound at the mix position, with high directivity. That's actually a BAD idea, because it makes your sweet spot very small: if you move your head just a bit, then your ears are outside the "focus", and off-axis from the smooth, clean frequency response. Far better is to choose speakers that have the directivity pattern that matches the room, and allows for a good size sweet spot that extends all around you as far as possible. (But do be careful! It is NOT just the speakers that determine the size of the sweet spot: the room does. You can have the best speakers in the world, with the broadest sweet spot ever, and in a badly desisted room the ACTUAL sweet spot could still be a single pin-point, where you need your head held stationary in a vice to keep it stable! And vice-versa: Even speakers that have a poor directivity plot set up properly in a great room, can usually have a wide, clear stable sweet spot.

Quote:
I like the Tannoy sound,
Then that's a problem! Good speakers should not have any "sound" of their own! They should simple reproduce exactly what you feed them. I always get annoyed when I read reviews of speakers by supposed "experts", saying that the XYZ491s that they test sounds "warm" or "deep", or "bright" or "full", or had good "punch" or "definition". To me, all of those mean that the speaker was pretty lousy, since it was enhancing some aspect of the sound, instead of just telling the truth. Do you REALLY want a speaker that enhances all the high-mids to give a "bright" sound, and also has good "punch" in the low end? If you tried to mix on those, you'd end up COMPENSATING for their skewed response, and your mixes would not translate well: your mixes would LACK brightness and punch when played elsewhere.

Instead, get the most neutral, uninteresting, flat sounding speakers you can afford. Do NOT get the ones that "sound like" something. Check the specs, look at the frequency response plot, but more importantly the time-domain plot, and the directivity plot, to make sure that the ones you choose are as flat as possible in all senses. It is dead easy to compensate for pure frequency response issues in your speaker, very much harder to compensate for phase issues, and practically impossible to compensate for time-domain issues with the speaker itself, such as resonances.
Quote:
I can add my sub later. Or buy/build a better one.
Or you could get a pair of mains that don't need subs! Or you could decide to get mains that do NOT go down very low, and add a COUPLE of subs to fill in the bottom end. There are many options, and it depends mostly on what you NEED to do in that room, as well as the room itself.

Quote:
1) Should I measure my room in it's current form, with my current speaker/sub set-up
It's always good to have a "baseline" REW data set, to compare against.

Quote:
2) Should I first re-orient and re-organize my room before meauring with my current speaker/sub set-up?
That's also a good idea, as it would give you a second set of data to compare, and see what changes with an alternative setup.

Quote:
3) Should I first re-orient and re-organize my room AND install different monitors before measuring?
That would be the third step, after the first two, once you have decided on your new speakers and set them up correctly.

Quote:
4) How I can sensibly judge which monitors I want to use in my room, if the current acoustics suck?
Compare the room dimensions with the speaker specs, and your own personal needs! :) Simple to say, but not so simple to do...

---

Quote:
However, and I’ve come to this realization more than once, I somehow prefer the sound if the sub does as little as possible.
You should not "prefer" any sound! Rather, you should go with what gives the smoothest MEASURED response in your room. I'd really like to see that first REW test of how your setup is performing right now: my guess is that it is not nearly as even and smooth as you think it is. Probably the setup "sounds" good because the deficiencies of that setup happen to mask some of the deficiency of the room and the speakers, to a certain extent.

To put it simply, this is your goal: viewtopic.php?f=2&t=20471 Look at the REW graphs for that room, run the tests in your own room (exactly as explained here: viewtopic.php?f=3&t=21122 ), and compare.

Quote:
That also helps integration with the mains, is my experience.
Almost never. It usually masks problems with either the speakers, or the room, or both. But masking a problem is not fixing it. If you have an alarming loud rattle in the engine of your car, then turning up the radio to mask that sound is not fixing it! :)

Quote:
I’ve tried running the sub higher, but it becomes boomy very quickly.
Your honor, I rest my case! :) Exactly. You just proved my point. You are using the gross imbalance between the subs and mains and the incorrect EQ fo the cross-over, to mask a major acoustic problem in your room. You did not make the "boom" go away: all you did is to skew the frequency response so that it is less annoying, but it is still there, and still mangling the overall behavior of the room. At a guess, it's probably the first-order lengthwise axial modal response that yo a re trying to hide (but not succeeding), which is why your mixes don't translate seamlessly, and also why: " some problems in the low bass range" and " I want my mixes to sound better overall", as well as "Bass is difficult" and "the mid-range balance and clarity are also greatly compromised". The basic modal response of the room, combined with the SBIR response, sets the overall "signature" of the room, and you CANNOT hide that with EQ, which is what you are trying to do. The problem is still there... It does not sound logical that mis-setting your cross-over could be related to the reason why your high-mids sound off, but that's exactly what happens.

Quote:
Moving it around the room doesn’t really improve things
Then you likely have a listening position problem, very likely modal. You CANNOT fix a modal issue with EQ. Modal issues are purely in the time domain, and EQ can ONLY deal with frequency domain. Trying to fix modes with EQ is like trying to fix a flat tire on your car by putting more fuel in the tank.... Pointless, and actually makes things worse, not better.
Quote:
Translation to other systems is not *that* bad…
Which implies that it isn't really good either!! :) 8)

Quote:
Why would rotating the room 180 degrees help? Because I’m no longer facing the window and can symmetrically treat the (new) front wall?
Exactly: Facing a window isn't a problem, but symmetry is. The front one third of the room must be SYMMETRICAL. This is critical. If not, your sound stage will not be accurate: it will be skewed one way or the other, and you won't be able to place instruments accurately in the mix. Your stereo image will also be "off", and you'll tend to correct that problem, even though it isn't really there! And since asymmetry is usually frequency dependent, some parts of your mix spectrum might not be affected at all, while other parts are totally trashed...

So I'd suggest that you start out by doing the basic set of REW tests with your room set up exactly the way it is right now: don't change a thing. Post the results here, and we'll analyze them for you, so you can see where you stand right now. Then based on that, you can decide which way you want to go, and how far you want to take it.

- Stuart -



- Stuart -

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PostPosted: Fri Jul 06, 2018 3:37 am 
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A few things in your last post, Stuart, that I like to get back on.
- I know my acoustics are the problem. That's why I'm on this forum in the first place. I have an issue that needs fixing.
I'm not sure how my preference to have the sub cross-over lower than the usual 80-100Hz is related to my room. Yes, it's very well possible - if not certain - that doing this in my particular situation helps to mask a problem. But why should a sub be crossed over at 80-100Hz? At least: that's how I interpret your comments on my use of my sub. I suppose the complete answer to this question might be enough to start a new thread :wink: I'd like the short version for now ;-)

And yes, my mixes translate reasonably well, not perfect, because of the problematic acoustics in my room. Again, that's why I'm here. This room is a mess, not just acoustically :lol: I have absolutely no illusion that it sounds anywhere near good. However, given the current situation, I've learned to deal with it and mix more or less satisfactory. The result is not as bad as I would have expected. I do want things to be better, though.

I understand your vision of speakers as "a black box that produces sound" that you mention in another thread I've responded to. I also understand why you state that any speaker with a particular "fingerprint" is a speaker that's essentially unsuitable for mixing duties.
But, if the case is that any speaker that posessess certain traits is suitable for mixing duties (in a purpose-designed room), then why do people favour some speakers over others? Let's face it: given a certain set of needed specifications for a certain room/task, more than one set of monitors will fit the bill. Right?
I know the Genelec 1031/1032 is highly regarded, as is the ProAc Studio 100. The Avalon Mixing monitor is a fantastic monitor speaker (I worked on them for several years and adored them!). They all have roughly the same frequency range. We've established that I'll need frequency response to around 40Hz, so I'll be looking for something that has-3dB at around 35Hz. There's a whole bunch of monitor to be found that can do that, including (but not limited to) the ones I mentioned. So my question really is: Based on wat specifications should I choose my next set of monitors? How do I decide which ones to get (besides cost...)?
Once I've made my choice, the room can be designed around them. In an ideal world, at least. My situation unfortunately isn't part of that ideal world, since we're dealing with house that people live in. I fear I'll have to do with as good as is possible given the circumstances. Which I hope to make better for the purpose of this whole endeavour. Anyway...

Soundman2020 wrote:
The Sound Guy wrote:
because it's a sort of horn, it has the benefit of having very good directivity and focus
Are you sure you want that? And it's not really a valid point anyway: pretty much all studio reference monitors that I'm aware of have very carefully engineered horns on the tweeter: If they didn't the impedance mismatch between the cone and the air would create very poor frequency response, and the thing would sound pretty ugly. It's a myth that you should get a speaker that "focuses" the sound at the mix position, with high directivity. That's actually a BAD idea, because it makes your sweet spot very small [...]

Does this mean you dismiss Tannoy dual concentric speakers as suitable monitors? I've seen documentation of JBL LSR[something or other] that measured impressively flat both on- and off axis. According to JBL, at least. But these have waveguides, too.

I need to get going.
Let me conclude by saying that I plan to do some measurements when I have a) figured out how REW works and b) enough time to actually get to it. Including calibration, which will require an SPL meter that I don't yet have.

In all honesty, I do hope that you, Stuart, or some one else who can meaningfully chime in, can explain the above. Basically, If all speakers are created equal (so to speak), than why ore some created more equal than others? If you know what I mean... ;-)
I've worked as a mixing and recording engineer for quite some years, but I've never looked at monitors this way; from the eyes of an acoustics engineer. Very nice to be able to do that now. But it seems I get to re-evaluate some things I though I knew.... (which is good!!!)

The Sound Guy


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PostPosted: Fri Jul 06, 2018 6:22 am 
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Location: Santiago, Chile
Quote:
But, if the case is that any speaker that posessess certain traits is suitable for mixing duties (in a purpose-designed room), then why do people favour some speakers over others? Let's face it: given a certain set of needed specifications for a certain room/task, more than one set of monitors will fit the bill. Right?
If you put someone into a truly neutral mixing environment for the first time, even someone who has a fair amount of experience, they will very likely not like it at first. They will say it sounds lifeless, uninteresting, "bland", "off", "flat" etc. By "truly neutral mixing environment" I mean one that fully meets BS.1116-3, or TECH-3276, or other similar specs. First-time exposure to that is a downer: it does not meet expectations, PRECISELY because of what you say! Many people are used to a certain speaker or a certain type of acoustic response, and think that's how things SHOULD sound. When they are put in an environment that has no sound of its own, and is truly transparent, they are disappointed. They expected to be blown away by the deep growling rumbling roaring bass, and the shrill highs, but all they get is pure, clean neutrality... Most are not impressed.... Until they start mixing in there, and discover that they can hear things they never heard before. They soon change their minds, but it takes time. Once they start noticing the extreme clarity, the full tightness of the bass, the total truth of what they are hearing, the absolute ease of putting together a mix that just works, and works anywhere else too, effortlessly, then they start to appreciate it. Because it is clean, clear, truthful, and like nothing they heard before, and it makes their job so much easier. It takes some getting used to, but once you do there's no going back. Everything else just sounds so over-hyped and muddy.

That was the case with Rod at Studio Three, for example. When he first tried listening to stuff after the initial treatment was in, he wasn't that impressed. Until he REALLY started LISTENING, and hear stuff in his own previous mixes that he had no idea was there! Even though he had tracked and mixed those songs himself, and knew them intimately, he was rather shocked to hear things that upset him, that he had never noticed before, because he had never been in such a truly neutral, flat, brutally truthful room before. Then he started loving it! He understood WHY it had to be that way, and started really enjoying it. And as a bonus, I added a "blow them away" setting on the final tuning, so he could switch to that when he REALLY wanted to impress the hell out of someone, with deep growling roaring bass, and airy, sparkling highs. When the room is treated to perfection, it is possible to do that with the tuning. You can make it "sound" any way you want. So today Rod has his "clean neutral" setting for mixing stuff perfectly, and he has a "blow them away" setting for pure listening pleasure, and putting wide-eyed jaw-dropping expression on the faces of friends and visitors. But he does not MIX in that setting: it would turn out pretty bad if he tried...

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They all have roughly the same frequency range.
Actually, the frequency response of your speaker and room is NOT the most important acoustic measurement. That's a common misconception. When I'm tuning a room, I don't bother with frequency response at first, because it is not top priority. I am far more interested in the impulse response, the phase response, and the time-domain response. Those are what really matter. Getting those in order is much, much harder than getting the frequency response flat. Yes, the frequency range is important in the sense that the speaker must cover the spectrum that you need reasonably evenly (no large dips or bumps), but that's about it. It is far, far more useful to look at the time-domain characteristics of the speaker itself, because you CANNOT fix those with room treatment or digital tuning. If there's a slight hump or dip in pure frequency response of the speaker, that is not associated with a phase or time issue, then I really don't care: I can fix that in the room, or by tuning. But if there's a phase issue, or a time issue, then that speaker is not much use, because I can't fix that. And those types of problem are far, way, extremely more important than frequency response, THD, maximum power output, or any of the other characteristics that people go chasing after, but are meaningless. I don't care if the speaker has THD of 0.001%, or 0.01%, or even 0.1%. You will NEVER be able to hear those THD "issues" in a typical setup. Unimportant (most people would be very hard pressed to notice even 1% THD, and maybe just barely pick up on 5% THD). Ditto for SPL: if Speaker Brand A produces 119 dBC at max, but the equivalent model of Speaker Brand B only produces 116 dBC, then frankly I don't give a damn! I would not care much either way, since both are more than adequate. But if the time-domain chart shows that there is luffing going on in the reflex port with "A" while "B" is clean, then you can bet I'll drop "A" right there. And if there is some form of resonance going on with the speaker cabinet, or the mountings, or the drivers, then ditto: that speaker is no use to me, no matter how good it "sounds", Because part of that "sound" is likely due to the ringing! It might sound pleasant, warm, airy or whatever other name you want to use, but it won't be NEUTRAL, which is the most important aspect. Ditto if I look at the phase response, and see that things go wild around the cross-over frequency. Speaker is no use.

But most people look at the FR (Frequency Response) plots, and decide what to buy based on that. Or they listen to several, and decide on the "warmest" one, or the "most musical" one, or the one that has best "clarity" in the highs. All of those are subjective, and not very relevant. If you listened to ten speakers and tell me that one sounded "subdued" and "boring" and "bland", then I'll be mighty interested in taking a closer look at that one, since it is very likely to have the best overall characteristics!

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We've established that I'll need frequency response to around 40Hz, so I'll be looking for something that has-3dB at around 35Hz.
Fine! That's a good starting point.

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So my question really is: Based on wat specifications should I choose my next set of monitors? How do I decide which ones to get
Check time domain response first: get a waterfall plot or spectrograph for the speaker itself (taken in an anechoic chamber). If it looks smooth across the entire spectrum, then that's a good sign. Then check phase response (a clue to that is group delay, yes but, but that's not the entire story). If the phase response does not descend smoothly across the entire spectrum, then there's a problem (assuming you can even find the phase response graph! Many manufacturers don't publish them). Then check dispersion: If you have a long narrow room, don't get a speaker that has a very wide dispersion pattern, or you'll be sending too much of the mids and highs directly to the walls, where you'll get reflections and comb filtering issues. Ditto if you have a wide room: don't get a speaker with a narrower dispersion pattern, or it won't fill the room smoothly, and you'll have trouble getting a good reverberant field. Then check distances. If the manufacturer says that the closest listening distance is 2m, but your desk is only 1.8m from the speaker position, then that speaker is no use for you (this has nothing to do with so-called "near-field" or "far-field" monitors, or even worse the "mid-field"! Different subject). Then check the physical size: Is it suitable for your room? Is the speaker maybe too deep? Too narrow? Too tall? Too large overall? That's related to how you plan to mount it as well, of course, as well as the correct geometric setup. Related to overall dispersion, is the "coverage" or smoothness of the dispersion, in frequency and time. You might find that you have a great speaker with the perfect dispersion angle for your room (eg, 75°, for example), but between 5° an 12° off axis, there's a dip in some frequencies, and between 9° and 17° there's a peak in other frequencies... etc. Sometimes the overall numbers look good, but when you get into the details, it ain't so good. Then mounting: If you plan to soffit-mount your speakers (highly recommended!) then a speaker with a reflex port, driver, or passive element on the side, top or bottom would be no use, but ones with ports on the front or back are fine.

Those are just some of the aspects that I'd look at.

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Once I've made my choice, the room can be designed around them.
Yes, true, assuming that the room doesn't exist yet! In your case, your room is already there, so that imposes some limitations on your choices, to start with. So choose one that fits your room, then design the REST of the room around it.

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My situation unfortunately isn't part of that ideal world,
There's a saying around here: "If that room is all you have, then it's still a hell of a lot better than not having any room at all!" Pretty much any room can be improved, acoustically. Not all can be made great, or even good, but most can be drastically improved.

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Does this mean you dismiss Tannoy dual concentric speakers as suitable monitors? I've seen documentation of JBL LSR[something or other] that measured impressively flat both on- and off axis.
See if you can get a full directivity plot for those, presented in this format:
Attachment:
kh120_hor_directivity_510.gif


That tells you pretty much everything you need to know about the speaker. If you can find that plot for the ones you are considering, then comparison is easy. That's for the KH120, and it shows a really good speaker. That would be very nice for a typical room, but maybe not so goof for a very wide or very narrow room (it has smooth, even dispersion right out to 50° off axis either side, and right across the spectrum, all the way up to 20 kHz, at only -6dB to -9dB! Impressive).

Here's an example of a really bad speaker:
Attachment:
bad-speaker-directivity-plot.jpg


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that measured impressively flat
Once again, flat frequency response in the manuals for a speaker isn't much use. It could be a ruler-flat straight line from 20 Hz to 20 kHz, and that makes no difference to how it will sound in YOUR room. Those measurements were done under carefully controlled conditions in an huge anechoic chamber, but when you put that speaker in a REAL room in the actual normal world, the response will not be anywhere near flat, because the room loads the speaker! The room itself presents an acoustic impedance to the speaker, and the speaker responds to that. The actual frequency response of the speaker will be FAR from flat in your room. Take a look at Studio Three once again: This is the response of those beautiful Eve SC-407's in the empty room:
Attachment:
RMOUS--original-FR--no-panels-or-adjustment--01.jpg

Those are GREAT speakers, with nearly flat response across the entire spectrum, but the room is loading them, and coloring them, and interfering with them rather badly, as you can see there. The ROOM is doing that to the speakers. Now you can see why it doesn't really matter that much what the FR curve looks like for a speaker, as long as it isn't grossly uneven. The graph in the manual shows how the speaker will responds under prefect conditions, but any room you put it in, is NOT perfect. So it will NOT respond with the same flat FR graph.

After completely treating and tuning the room, this is what we got:
Attachment:
RDMOUS--REW--FR-18-22k..3.png


Problem solved! But even then, that's the LEAST important aspect of that setup. The TIME domain is far more revealing. Empty room, low end (below 500 Hz):
Attachment:
RDMOUS-waterfall--untreated-room-20-500.jpg


Final completed room, low end:
Attachment:
RDMOUS--REW--Waterfall-final-18-500..48.png



Completed room full-spectrum:
Attachment:
RDMOUS--REW--Waterfall-final-18-22k..3.png

(This covers the same frequency range as the previous graph, but the graph itself is wider, more stretched out. Don't let that fool you.)


As you can see, it is the time-domain control that matters most, NOT the frequency domain. If you get the time-domain fully under control then the impedance loading of the room on the speaker becomes rather simple to fix, so it's easy to get the FR right too. If you start off trying to fix your FR first, you are doomed to fail.

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According to JBL, at least. But these have waveguides, too.
Let me clarify: ALL conventional reference monitors have waveguides! Every single one. If they didn't, then everything above the crossover frequency would sound absolutely awful. What the waveguide does, is to match the impedance of the driver cone (or dome) itself, to the impedance of air. There's a MASSIVE difference in impedance between air, and the very solid cone: even the lightest, strongest speaker cone material still has much higher impedance than air. The purpose of the waveguide is to match those two impedance, such that as the wave leaving the cone moves forward, it also spreads out, but at the correct rate, so that the energy can be smoothly transferred from the cone into the air BEYOND the speaker. No wave-guide = disgusting high end. If a manufacturer touts the fact that they have waveguides on their speakers, that's sort of like a car company advertising "We actually put WHEELS on our cars! With tires, too! Aren't we an amazing car company?". It makes them sound wonderful, until you realize that they aren't actually doing anything different from any other car company, because ALL cars come with wheels and tires. In the same way, all conventional speakers come with waveguides on the tweeters. That's a rather silly advertising ploy that I've never understood. Just as useless as saying "Our speakers come with a POWER CABLE so you can actually PLUG IT IN!!!!" :)

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Basically, If all speakers are created equal (so to speak),
They aren't! If you just look at FR, then it might seem that way, but once you look at the things that matter, you see that they aren't.

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I've worked as a mixing and recording engineer for quite some years, but I've never looked at monitors this way; from the eyes of an acoustics engineer. Very nice to be able to do that now. But it seems I get to re-evaluate some things I though I knew.... (which is good!!!)
:thu: To be very honest, any speaker in a lousy room will sound lousy. You can buy the most expensive speaker on the planet, with the flattest FR, 0.000000% THD, perfect dispersion plot, zero resonance, etc. and if you put it in a bad room, it will sound bad. Period. But in a room with GOOD acoustics, even a lousy speaker can sound sort-of decent, and a great speaker can sound incredible.

For the case I showed above: the Eve SC-407's in Studio Three, you can see how a speaker with supposedly flat response ends being far from flat, due to acoustic loading of the room, along with all the artifacts. That is NOT the speakers' fault! It's the room's fault. If I would have chosen a DIFFERENT speaker, then the FR curve would not have been exactly the same, but still rather bad. Similar to this, there would still have been large differences if I would have used an NS-10 or a Genelec 8050, or a Focal Trio, or whatever. Each would have reacted a bit different to the room, because the room loading is an IMPEDANCE issue, not a an FR issue. Each speaker has a different way that it reacts to impedance (such as, for example, the design of the waveguide, or the way the power amp damps the woofer cone, or any other number of things), so the FR curves would have had the same overall shape, but still with significant differences. So the FR you see when you put a speaker in the room initially doesn't mean a lot, and isn't the first thing I look at. It's useful, yes, but not the key. IR and phase are the key. Those will ALSO be mangled by the room itself (because: impedance....), but will .likely be more different than the pure FR plots. The goal of room treatment is to make them behave again.

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Let me conclude by saying that I plan to do some measurements when I have a) figured out how REW works and b) enough time to actually get to it.
It's actually not that hard to use for just taking measurements: I tried to make the instructions simple and clear. Interpreting the results is a different story! But just running the test is pretty easy. If you want to do a "quick and dirty but not accurate" test, then you could use an SPL app on your cell phone for a very rough first approach, then re-do the calibration and test once you have a proper SPL meter.


- Stuart -


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