Author: sandledfoot [ Wed Jun 12, 2019 3:05 pm ]
Post subject: Re: Erie Sound Studios Build (Sandledfoot returns)
I have questions...
I was under the impression that 60 gives you a wider sweet-spot (laterally) than that of 90, but your ear is more used to a direct on axis, so better to be closer to 90?
If my speaker is to be located at least 20% away from the side wall, then it seems the widest image I will be able to get in my size room is 60 degree.
Does that include the full width of the baffle? IE if the baffle is 40", does the edge of the baffle have to be 28" in? (28" is my 20% of my total room width, 120")
I believe I read that the speaker should be off of the front wall by 4"... what is the formula or standard or ... WHY? I am trying to maximize my room space and don't want the speakers into the room any more than necessary. 4" seems like a lot... what about 2" ? (just an example) The drawings show the speaker 8" off the front wall, which is close to equilateral triangle. (I know I am not beholden to that, it's as they say, just my starting point).
I have another questions I could not find a clear answer too. How do you determine the angle of the additional 'wing' baffles (circled in red)? I seem to run out of wall space.. in the overlay, my walls are in blue, and the baffle can be shown intersecting the wall directly...
how does the middle area between the baffles get filled? Hard or soft surface? It seems that there is an abundance of windows and doors typically located there. For me, I plan on mounting a large LCD/LED TV monitor, but this can change.
Do I seem to be on the right track?
PS- I hope John does not mind my using his sketch as a reference...
SketchQuestion.jpg [ 374.76 KiB | Viewed 149 times ]
Author: Soundman2020 [ Wed Jun 12, 2019 4:00 pm ]
Post subject: Re: Erie Sound Studios Build (Sandledfoot returns)
Be careful with raising and tilting your speakers... Yes it is possible, if you do it with a lot of care, and carefully check your reflection angles, and figure out your comb filtering, and how you will deal with that... But not recommendable. The highest angle I've ever done is a bit less than 5°, but that was far a room considerably larger than yours...
You say:
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I want them as high as possible to get them above my desk and computer monitors
Then you have the wrong layout for your desk and computer monitors!
Design your desk to be as low-profile as possible, and make sure that nothing sticks up above it very much. Then place your video screen as far forward as you can (beyond the desk, not on it), and as low down as you can while still being able to see it. If necessary, go with a bigger screen, further away, rather than a small screen up close. Keep the screen(s) well away from the direct path between speaker and ears.
Also, depending on your speakers, you can probably raise them a little WITHOUT needing to tilt anything: Check the dispersion angles and frequencies, and as long as your ears are still within the "good" section of the dispersion, no more than a couple of degrees off-axis, you'll be fine.
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thinking of Adam A77X, but I think I was talked out of that when I learned that the baffle width should be 3-5 times the width of the speaker woofer. My next choice is becoming the Adam A8X.
Ummm... the woofer diameter on the A77X is 7". The woofer diameter on the A8X is 8.5", so based on that "rule", your baffle surround would have to be 4.5 inches WIDER for the A8X, than it would for the A77X...
That said, the A8X is probably he better choice for your studio. If you are considering speakers in that range, then it's worth taking a look at some of the offerings from Eve Audio: they have nice stuff too...
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Listen position should be between 30%-38% of room depth. (my target was 38).
I try to keep it in the range 32% to 42% if possible. But that's just a starting point... sometimes you might need to break the rule, or bend it a little...
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Speakers should be aimed aprx 12-18" past listen position.
I think you are referring to the intersection of the speaker axes behind the engineer's head? Yes, that's correct. Once again, it's just a guideline: depending on the room, you might need to have the intersection closer to your head, or further away.
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I was under the impression that 60 gives you a wider sweetspot (laterally) than that of 90, but your ear is more used to a direct on axis, so better to be closer to 90?
60 and 90 what? Once again, I assume you are referring to the intersection angle behind the engineer's head? In either case, you still want your ears on-axis to the speakers, are close to on-axis. Your imaginary axis line drawn out from the acoustic center of the speaker should graze past the tip of your pinna in both cases. In your diagram, they seem to be a little too far out.
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I believe I read that the speaker should be off of the front wall by 4"...
That only applies to speakers set up on stands in the room: it does not apply to soffit-mounted speakers.
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what is the formula or standard or ... WHY?
It's all about baffle step response and SBIR from the front wall. Basically, your speaker emits low frequency sound in all directions, not just heading towards your head. The sound radiated "backwards" (behind the speaker, going towards the front wall of the room) hits the wall and bounces back, then interferes with itself causing phase cancellation at the mix position. The frequency where that happens depends only on the distance between the speaker and the wall. If the distance is between about one foot and four feet, then that produces a very deep "dip" in the low frequency response as heard at the mix position. THis is called "SBIR", for "Speaker-Boundary Interference Response" That's why, for people who are NOT going to have their speakers in soffits, the only solution for a small room is to push the speaker up tight against the from wall. That forces the SBIR dip up higher in frequency, out to the low end where it can't be treated and is very noticeable, into the low mid range, where it is less noticeable and where it CAN be treated... But you also need acoustic treatment between the speaker and the wall, and that will be about 4" thick, thus, you need to leave a 4" gap for that.
But none of the above applies to you, since you are planning to soffit-mount your speakers, so there won't be any SBIR from the front wall. That's one of the major reasons for soffit-mounting: it eliminates front-wall SBIR.
However, you WILL still need some space behind your speaker! It needs ventilation up the back to keep it cool, and there are other reasons why it should not be directly against the wall, so you still need to leave a good gap there.
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I am trying to maximize my room space and don't want the speakers into the room any more than necessary.
Then don't tilt them down!
That wastes space... If you leave them vertical, with no tilt, then they can be closer to the front wall...
Also, offsetting the speakers on the baffle face outwards, instead of inwards, can gain you a little extra space.
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how does the middle area betweetn the baffles get filled? Hard or soft surface? It seems that there is an abunduance of windows and doors typically located there.
It could be hard, or it could be soft, depending on what the room needs. I normally do REW tests at many points during the construction of the room, then decide on the front wall treatment based on that, when the time comes.
- Stuart -
Author: sandledfoot [ Wed Jun 12, 2019 4:25 pm ]
Post subject: Re: Erie Sound Studios Build (Sandledfoot returns)
Stuart,
As always, you give me (and others) so much help, thanks! I understand through your posts that there doesn't seem to be a hard and fast rule, but a series of guidelines to be used to accomodate your exact situation. I've been trying to design with that in mind.
The Adam A77X was the dual 7" monitors, so I was kinda assuming it acted somewhat close to 14" woofer... but I'm glad your OK with the A8X, they're a bit cheaper. I have looked at some of the Eve and Barefoot monitors as well, just depends on pricing I guess.
As for the tilt, I definitely will consider re-positioning the video monitors, and my desk is 31" high from the ground, so fairly standard. I wouldn't want something much lower because I wouldn't be able to sit under it... it definitely comes an ergonomics issue at that point. I should mention, that the bottom of the speaker as shown is only 4'2" above floor height. (In my first post, i mentioned my total ceiling height was only 95".
I'm still unsure of the side walls and angles coming off of the baffle. Any ideas for that? Is that just angled to prevent parallel walls to avoid slap echo? I also understand its supposed to be angled to direct reflections behind the mix position, but how is that determined? I can dray a line, but sound moves as a wave and it's hard for me to visualize the geometry.
Thanks again, your advice is much appreciated!
Kevin
Author: Soundman2020 [ Fri Jun 14, 2019 1:58 pm ]
Post subject: Re: Erie Sound Studios Build (Sandledfoot returns)
Quote:
As for the tilt, I definitely will consider re-positioning the video monitors, and my desk is 31" high from the ground,
That's a little high, actually. "Standard" desk height is 29" (depending on who you believe...), and most desks are 28" to 30". Studio desks are generally a bit lower, since you normally have a console sitting on it: I often use 26 1/2 to 27" for my studio desk designs. That still gives you enough knee-room.
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I wouldn't want something much lower because I wouldn't be able to sit under it... it definitely comes an ergonomics issue at that point.
Try it!
With a 27" desk made with a 1" top, you should still have at least 2" between the bottom surface and your legs. That assumes you have your chair set to get your ears at the correct listening height.
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I should mention, that the bottom of the speaker as shown is only 4'2" above floor height.
The height of the bottom, top, or center of yoru speaker is irrelevant...
What matters is the height of the acoustic axis. That's the point from which the sound seems to emanate, and is the key reference point for all measurements related to the speaker. The standard height for the acoustic axis is 120cm above the floor, which is 47 1/4". Depending on your speaker and room, you can normally go a litter higher than that. The objective is to have the acoustic axis of the speaker at the same height as your ears, or a little higher. Everything else in the room should be designed around that. The speakers are the very reason why the room exists at all, so the room should be designed around the speakers.
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i mentioned my total ceiling height was only 95".
You might want to consider flipping your speakers "upside down", with the woofer above the tweeter. That can sometimes help to get the woofer away from the modal nulls that happen at 50% of room height. Or you might WANT to have your speaker in the modal null, if you are expecting modal issues at problematic frequencies.
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I'm still unsure of the side walls and angles coming off of the baffle. Any ideas for that? Is that just angled to prevent parallel walls to avoid slap echo? I also understand its supposed to be angled to direct reflections behind the mix position, but how is that determined? I can dray a line, but sound moves as a wave and it's hard for me to visualize the geometry.
The entire concept behind RFZ design is that all of the surfaces at the front of the room are angled to redirect first-order reflections away from the mix position, leaving an "empty" region around the engineer's head where there are no reflections at all.
For high frequencies, sound behaves mostly like rays of light: for low frequencies, it behaves more like a balloon inflating. For intermediate frequencies, it behaves somewhere in between... sort of like an expanding cone. So, by carefully looking at the dispersion characteristics of your speaker, you can figure out what frequency range will be heading out at which angle, then based on that, figure out how it will reflect.
Having said that, you can get a pretty good idea from the "ray tracing" method. I have created a "ray-trace rainbow" in Sketchup, which I use when I'm designing studios. Here's an early version of that:
I've since developed that into a more sophisticated template that I can just attach to any speaker.
You use that by just seeing where the sound is going, and what angles it is hitting your surfaces at. You can then draw a line out from that surface, perpendicular to it, at any interesting point, see what angle the sound is ARRIVING at that point, then draw another line out from the same point, mirror-imaged, so it leaves at the same-but-opposite angle. You then assume a similar "rainbow" leaves that point, but you take into account the frequencies. For example, if you are looking at a ray that originated 60° off-axis from the speaker, then there won't be too much high-frequency content in that, so you'd be looking mostly at how mids would be reflect off that surface. Then you adjust the angles of the surfaces as needed, to ensure that you don't get any specular reflections at the mix position, or within a sphere around it.
- Stuart -
Author: sandledfoot [ Fri Jun 14, 2019 3:01 pm ]
Post subject: Re: Erie Sound Studios Build (Sandledfoot returns)
Stu,
I will take a close look tonight to see what the angles line up to be for first reflections. I think that was the key part I didn't udnerstand, so that helps. As for desk height, I am leary on changing the total height of the desk, but... it is on casters and if I take the casters off, then it would lower the desk by 2-3"... i'll have to look when I get home to be sure. My side car desk is at 26" so the faders are at wrist level. I built both of these desks a few years ago in my previous studio location and designed them to be taken with me. it would be a shame if I have to build new ones!
I see what your getting at with the speaker height, so I will revisit the angles. I am concerned that the 3/5 placement within the baffle is going to give me a problem (as it seems to run into the wall), so I am not sure how to get a 60d splay, keep the baffle width at 40" (for 8"woofer) and then add a wing wall to reflect sound away from the mix position. but, i'm sure it can be done!
Thanks for your time again,
Kevin
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Author: sandledfoot [ Tue Jun 18, 2019 3:30 pm ]
Post subject: Re: Erie Sound Studios Build (Sandledfoot returns)
So before I continue down this path of control room design... i've had a thought and I'd like some opinions.
I currently mix on Event TR8s and I like them. I am considering new Adam A8X monitors to soffit mount (as mentioned above), but I am concerned that the Adam A8X will not be that much of a departure from the current TR8, (not withstanding better top end). Specifically, I am looking for something that can be louder when needed. I don't mix at high volumes, but do push it when listening to the kick, bass and a few times before running my finals. That being said, I am starting to look at some higher wattage monitors. The Adam S2V and S3V seem like a good fit, but this is probably going to be beyond my price range... maybe. If this is an investment that I can use for 10years +, then I'll consider it.
for context, price listed per pair for readers perspective:
Adam A7X ($1,500)
Adam A8X ($2,000)
Adam S2V ($3,000)
Adam S3V ($5,000)
Eve Sc307 ($2,890)
Eve SC407 ($5,700)
Neumann HK310 ($3600)
Again, I really only want to design this control room once, and as Stu has reminded me, choose the speaker then design around that.
My question is this...
What would be an appropriate size/wattage for the control room of my size (12x18). Is there a target SPL that you aim for?
been following a few other threads here...
https://www.johnlsayers.com/phpBB2/view ... 2&start=30
Author: Soundman2020 [ Tue Jun 18, 2019 4:06 pm ]
Post subject: Re: Erie Sound Studios Build (Sandledfoot returns)
Quote:
I am concerned that the Adam A8X will not be that much of a departure from the current TR8, (not withstanding better top end). Specifically, I am looking for something that can be louder when needed.
I'm not sure I follow you here: How much louder than 120 decibels do you need?
That's already ear-damaging territory... If you are playing that loud, then I sure do hope you are wearing hearing protection...
120 dB is the threshold of pain, according to some sources (others say 125...). That's insanely loud for a control room. Most engineers mix at around 80 dB, and push it to 90 or maybe 100 to "check the bass", but pushing it to 120 is not a good idea at all. Why would you need more than that? I must be missing something here...
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The Adam S2V and S3V seem like a good fit,
... and they both put out the exact same maximum sound level as the A8X... Actually, the S3V can go 4 dB louder, but I really doubt you'd be able to hear the difference between 120 dB and 124 dB.... because you'd already be deaf after listening to the 120, so you'd never even hear the 124 at all!
You also have the SC407 on your list, which puts out 1 dB LESS than the A8X, so if you are looking for higher maximum sound level, then the SC307 and SC407 are not it. But if you are looking for fantastic quality, then either of those is a great speaker, as is the A8X. Here's a room I did with a pair of SC407s a while back: viewtopic.php?f=2&t=20471 That's a fairly large room, and there's way more than enough "oomph" in those guys to more than fill the room.
There's a typo in the last one on your list: It's the KH301, not the HK310. It's also a fine speaker, but it puts out the lowest sound level of all of them, at only about 110 dB. Still fine for the majority of rooms.
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What would be an appropriate size/wattage for the control room of my size (12x18)
Wattage is irrelevant. Wattage only tells you how much power the amp can produce without clipping. What matters is how much sound you get out of the speaker, for that amount of wattage. That depends on the efficiency of the driver design: higher efficiency drivers can produce more sound from the same number of watts, so looking at the wattage isn't very useful. Especially when you start to see that some manufacturers play games with the power ratings in watts, and quote peak figures, instead of RMS. It's been a while since I last saw it, but a few years ago there was a fad among some manufacturers of really lousy, low quality speakers to quote the power rating in the fictitious units of "Watts PMPO", meaning "Peak Music Power Output"... which basically meant how much power could the driver absorb before it fried in a large puff of smoke, when you pumped in stupidly huge amounts of power for a tiny fraction of a millisecond....
For studio monitors, forget watts: look at the actual sound pressure level that the speakers can produce. Your ears hear decibels, not watts.
(OK, before some pedantic purist comes along and says that I'm wrong, and you DO hear watts, let me clarify: you hear acoustic watts, not electrical watts. Power amplifiers put out electrical watts, which the driver turns into acoustic watts. And the number of acoustic watts you get depends, once again, on the efficiency of the driver. A typical speaker pushed to its peakwill only put out about one watt of acoustic power, probably less... when you consider that the amp is producing many hundreds of electrical watts to achieve one acoustic watt, you realize just how inefficient drivers really are... And to put all that in perspective, a full symphony orchestra puts out about one watt of acoustic power).
Hope I didn't confuse you too much!
- Stuart -
Author: sandledfoot [ Tue Jun 18, 2019 8:10 pm ]
Post subject: Re: Erie Sound Studios Build (Sandledfoot returns)
Stuart,
I understand, and I agree, I am not planning on mixing at over 90db very often, and then in short increments to check something specific or the final mix. I am also at the limits of my knowledge in terms of understanding how speaker efficiency and wattage convert to db, but I do understand that as a general rule, the more watts available from the amplifier, the cleaner the speaker can deliver audio (in addition to being louder). That is what I am after, in terms of being able to have something that is capable of delivering very clean audio, at high volumes, without stressing the amplifier, speaker or sacrificing quality. I mean, there is a reason the S series costs more and has more watts than the AX series, right?
I have a good bit of experience with live sound, so i'm familiar with keeping tabs on db and and understand the basics of sound reinforcement, i'm just trying to apply that to the control room environment.
Its good to hear the A8X is something your still encouraging... it's definitely more affordable than the other options. I am going to see if I can do a bit more homework, look at your thread and go from there.
As always, I appreciate your input.
Kevin
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