There has been a lot of discussion bantered about on what the actual SPL requirements for a loudspeaker system design are. I recently read a book "Sound Systems: Design and Optimization" by Bob McCarthy. In it he has a table of SPL values (figure 1.14). Since his numbers are completely consistant with what I have been saying, I thought that I would quote them here. This makes two highly credible references for design goals in terms of SPL.
These are listening levels at the seating position and all numbers are dB SPL with no weighting.
High Level Music: 103 - 112 dB with peaks to 115 - 124 dB
Medium Level Music: 91 - 100 dB with peaks to 103 - 112 dB
Low Level Music: 79 - 88 dB with peaks to 91 - 100 dB
Now if these are at the seating position then typically we would want to add 3-6 dB for the 1 meter levels, but this, of course, depends on the room.
Clearly to design a system where one wants to be able to handle High Level Music without major overloads the design target must be 125 - 130 dB at 1 meter. A speaker like this would never overload under any conditions even in a fairly large home room or home theater.
A 90 dB 1 watt 1 m speaker (a common small two-way) would need 10,000 watts to achieve this. A 100 dB 1 watt 1 m speaker (about the limit of design) would still need 1000 watts. A 100 watt amp is going to be clipping for the 100 dB speaker for some of the peaks when listening to High Level Music (which may be tolerable, based on my experince it would be). The 90 dB speaker will clip virtually all of the peaks on even Medium Level Music (based on my experience this would sound pretty bad.)
I suspect that these numbers are much higher than what most people suspect, but are completely consistant with my own opinions, experiences and observations. These are the numbers that I design to - and achieve. Others may target the Low Level or Medium Level, but clearly they will not be capable of achieving "High Level Music" or work in larger rooms without serious overload quality degradations or failure.
These are listening levels at the seating position and all numbers are dB SPL with no weighting.
High Level Music: 103 - 112 dB with peaks to 115 - 124 dB
Medium Level Music: 91 - 100 dB with peaks to 103 - 112 dB
Low Level Music: 79 - 88 dB with peaks to 91 - 100 dB
Now if these are at the seating position then typically we would want to add 3-6 dB for the 1 meter levels, but this, of course, depends on the room.
Clearly to design a system where one wants to be able to handle High Level Music without major overloads the design target must be 125 - 130 dB at 1 meter. A speaker like this would never overload under any conditions even in a fairly large home room or home theater.
A 90 dB 1 watt 1 m speaker (a common small two-way) would need 10,000 watts to achieve this. A 100 dB 1 watt 1 m speaker (about the limit of design) would still need 1000 watts. A 100 watt amp is going to be clipping for the 100 dB speaker for some of the peaks when listening to High Level Music (which may be tolerable, based on my experince it would be). The 90 dB speaker will clip virtually all of the peaks on even Medium Level Music (based on my experience this would sound pretty bad.)
I suspect that these numbers are much higher than what most people suspect, but are completely consistant with my own opinions, experiences and observations. These are the numbers that I design to - and achieve. Others may target the Low Level or Medium Level, but clearly they will not be capable of achieving "High Level Music" or work in larger rooms without serious overload quality degradations or failure.
100dB peaks would be called 'loud' by most people (not in here though). 110 dB peaks I think would be called 'high level' by most people in here.
I think the 'requirements' get skewed because max SPL isn't so necessary to achieve, but high SPL speakers tend to have some advantage at more modest reproduction levels- in other words, the design of such speakers has some features that lead to both high max SPL AND dynamic production at more reasonable levels.
This is all in the context of home music reproduction of course. I tend to like speakers that have a ton of headroom but I listen at pretty modest levels most of the time. I find that these types of speakers are able to maintain an expanded dynamic envelope at low volume pretty often.
A good counterexample would be heavy, high damping cone speakers- people tend to need the 'hifi' 4 way behemoth towers to get cranked to enjoy proper reproduction dynamics, but a similar sized driver complement with pro style (high SPL, high Qms, monster motors) tends to retain a more dynamic sound at lower levels.
So IMO, the high SPL requirement has more to do with the coincidence of the features needed to meet this with those needed to achieve good low-level dynamics.
I think the 'requirements' get skewed because max SPL isn't so necessary to achieve, but high SPL speakers tend to have some advantage at more modest reproduction levels- in other words, the design of such speakers has some features that lead to both high max SPL AND dynamic production at more reasonable levels.
This is all in the context of home music reproduction of course. I tend to like speakers that have a ton of headroom but I listen at pretty modest levels most of the time. I find that these types of speakers are able to maintain an expanded dynamic envelope at low volume pretty often.
A good counterexample would be heavy, high damping cone speakers- people tend to need the 'hifi' 4 way behemoth towers to get cranked to enjoy proper reproduction dynamics, but a similar sized driver complement with pro style (high SPL, high Qms, monster motors) tends to retain a more dynamic sound at lower levels.
So IMO, the high SPL requirement has more to do with the coincidence of the features needed to meet this with those needed to achieve good low-level dynamics.
Design considerations aside, a check with a meter at listening positon suggests to me music volume levels in the 70's dB is loud enough to make most speakers "sing."
In the 80's dB, it's loud enough to make one shout to be understood just a few feet away- and in the 90's you'll likely be experiencing temporary threshold shift (TTS), in seconds.
Listening to music for extended periods at higher levels will cause permanent hearing loss. Be warned, OSHA suggests that with 20 years of loudness levels at 70dB your likelihood of permanent (Rated at -25dB) hearing loss is about 15%. At 95 dB it 35% and at 100dB it's a whopping 70%!!
I do wonder about that "singing" thing. Some speakers do low volumes really well, some have to be turned up to a certain level to reach their "sweet spot." Could it be my hearing loss?
In the 80's dB, it's loud enough to make one shout to be understood just a few feet away- and in the 90's you'll likely be experiencing temporary threshold shift (TTS), in seconds.
Listening to music for extended periods at higher levels will cause permanent hearing loss. Be warned, OSHA suggests that with 20 years of loudness levels at 70dB your likelihood of permanent (Rated at -25dB) hearing loss is about 15%. At 95 dB it 35% and at 100dB it's a whopping 70%!!
I do wonder about that "singing" thing. Some speakers do low volumes really well, some have to be turned up to a certain level to reach their "sweet spot." Could it be my hearing loss?
You are dramtically mistating reality.
No hearing loss occurs at levels below about 80-85 dB - ever! The OSHA standards allow 100 dB for two hours without protection!! My wife is an audiologist, I live with this stuff and your numbers are incorrect. I stand by the numbers that I posted above. They are correct.
20 years at 100 dB is absurd. Damage is a time AND level effect and your times are excessive. NO one spends 20 years at 100 dB, so where did those numbers even come from. Ridiculous.
No hearing loss occurs at levels below about 80-85 dB - ever! The OSHA standards allow 100 dB for two hours without protection!! My wife is an audiologist, I live with this stuff and your numbers are incorrect. I stand by the numbers that I posted above. They are correct.
20 years at 100 dB is absurd. Damage is a time AND level effect and your times are excessive. NO one spends 20 years at 100 dB, so where did those numbers even come from. Ridiculous.
peak
just in case there could, perhaps, be some argument* it might be useful to say what "peak" means in this context.
I guess it is just the instantaneous (and, as you said, unweighted) maximum. In that case, with most music, it bears little connection to any issue of exposure or safety.
*though personally I don't see why: I'm listening to very modest 90db rms and 100~103 dB peaks at the moment and it certainly fits the description of medium level.
(I think high level would make my ears ring a little though, after ~ an hour.)
Ken
just in case there could, perhaps, be some argument* it might be useful to say what "peak" means in this context.
I guess it is just the instantaneous (and, as you said, unweighted) maximum. In that case, with most music, it bears little connection to any issue of exposure or safety.
*though personally I don't see why: I'm listening to very modest 90db rms and 100~103 dB peaks at the moment and it certainly fits the description of medium level.
(I think high level would make my ears ring a little though, after ~ an hour.)
Ken
gedlee said:
These numbers are pretty real in pro reinforcement practice. I.e. loud clubs and live events. I have lived that reality as a live sound engineer and general applications pro installer. There, the audience yelling and activity, keeps the noise threshold very high, and the anticipation for fun preconditions people for peak levels they will not normally tolerate for listening to recordings at home.
I would subtract roughly10dBs out of each number mentioned in your post for home listening.
All of these later posts are reasonable and if you want to subtract 10 dB for home listening thats fine.
Thanks for the OSHA posting. Note that those are dB(A) and "Slow" meaning more like 110 dB(C) (a guess) and peaks to 120 dB are allowed by OHSA for 2 hours. Two hours at that level would deflate me too.
Thanks for the OSHA posting. Note that those are dB(A) and "Slow" meaning more like 110 dB(C) (a guess) and peaks to 120 dB are allowed by OHSA for 2 hours. Two hours at that level would deflate me too.
gedlee said:
"a room"? "a larger room"?
😕
how much larger?
aren't "sound systems" from McCarthy's book a "Public Address sound systems"?
from Amazon descritpion:
an audience and a PA system in a living room ?
😕
salas said:
noise threshold is very important because human hearing is sensitive to relative SPL
so the lower the ambient noise the less dB and Watts is needed
Re: Re: SPL targets for speaker design
You are correct about the book, but SPL doesn't know the size of the room. SPL is SPL big room or small, it doesn't matter.
graaf said:
You are correct about the book, but SPL doesn't know the size of the room. SPL is SPL big room or small, it doesn't matter.
One could argue it is even worse (lower) than this. Most 2-way DIY designs I've seen using low efficiency drivers with adequate baffle step compensation are between 83dB and 87dB @ 1 watt 1 m.
I think raw power requirements to drive a low efficiency system to high levels are not the issue. The limit becomes the excursion limitation of the bass driver(s), which in the systems I've modelled is less than 50 watts. In this example, the speakers are being run full range with bass effects.
I think a useful extension to this discussion would be to state what swept volume is reasonably required to provide bass at Earl's SPL levels above (ie. Sd * cone displacement). We'd also need to identify typical listening room sizes and possibly room materials and add that to the "SPL matrix".
Regards,
David.
gedlee said:
No hearing loss occurs? OSHA does not state that. OSHA is aimed at preserving the ability to understand speech. Do you want to hear a highhat or brushed cymbals or do you want to be able to understand a phone conversation? It is your decision.
I am not arguing with your SPL targets, just your rather brusque dismissal - audiology is not like engineering, it is more like psychology in its reliance on statistics. Now what does it take to get that target level at acceptable distortion levels? Would your wife let you put it in your living room?
Dave Bullet said:
2-4 (or more, depending on enclosure design) 15" woofers would be needed to reach 120dB at 20Hz with reasonably low distortion.
No they don't, but its true none the less.
It was an unreasonable post. Audiology is engineering, I've done enough of it to know. The distortion issue is addressed elsewhere. Well yes actually I have a set in the living room and the home theater.
Those numbers are very consistent with my own observations.
I do think though it is important to note that those levels are for music... if you have, say a 3-way system, the requirements of the individual channels and sections are a little less.
My personal design standard is to be able to hit 112-115 dB peak in the 80-10k Hz range per channel and 125 dB peak 30-80 Hz in the mono sub, those all being at the listening position. I find that a system that can do that rarely runs into the limits (and believe me, I like to lean on it a bit now and then). With a setup like that, even at full volume listening the A-weighted slow time constant SPL is rarely over 105 dB, and usually in the 95-100 dB range.
I do think though it is important to note that those levels are for music... if you have, say a 3-way system, the requirements of the individual channels and sections are a little less.
My personal design standard is to be able to hit 112-115 dB peak in the 80-10k Hz range per channel and 125 dB peak 30-80 Hz in the mono sub, those all being at the listening position. I find that a system that can do that rarely runs into the limits (and believe me, I like to lean on it a bit now and then). With a setup like that, even at full volume listening the A-weighted slow time constant SPL is rarely over 105 dB, and usually in the 95-100 dB range.
Dave Bullet said:
I think you'll have a very difficult time answering this question because the sub to listening position transfer function at low frequencies is so highly dependent upon the position of the subwoofer(s). For example, if you look at the Harman multiple sub white paper, a couple of the configurations varied on the order of 10 dB... nearly a factor of 4 in terms of displacement. And keep in mind that is with a FIXED room... let the room vary and things get harder to pin down in general.
I can give you an example of a system that will do it though. I run 4 Mach 5 MJ-18s ported (3.5 cubes each tuned to 30 Hz) off of a Behringer EP2500. In terms of half-space 1m SPL if all the drivers were located at a point (just for comparison), that would do 127 dB at 30 Hz, 131 dB at 40 Hz, and 133 dB from 50-80 Hz. Those numbers are not to be thought of as in room... since the subs are often radiating into quarter or eighth space, more than 1m away from the listeners, and placed in different locations around the room. In the handful of rooms I've had these in and the varied placements within those rooms, they have got the job done with a little bit to spare. I used to run an ever bigger setup (8 15s in 5 cubes each ported with two EP2500s on the mix) and that was definately overkill, so I ditched the extra unused output (about 6 dB compared to the new setup) in favor of 1/3 the total size and half the power. I really only do music though... if I wanted sub-30 Hz info for theater I may have kept it around.
"100dB peaks would be called 'loud' by most people (not in here though). 110 dB peaks I think would be called 'high level' by most people in here."
Hello badman
Well that depends on what your playing. Well recorded material you can have high peak values that you don't perceive as loud. Try using a digital SPL meter with a record function. I use one from time to time and have been surprised at peak levels recorded. Using an 85-90db average it's not at all uncommon for it the record 107-108 peaks as an example. I was just messing with my 2 channel system and was getting peaks in the 113db range. Ran out of power as well and when you work the numbers it was right where it should be. It was loud but not at all uncomfortable.
Lets face it most speakers are simply on the wrong side of the power curve. If you are not starting out close 100db 1 watt 1 meter you are going have a real tuff uphill climb if you can even get there.
Rob 🙂
Hello badman
Well that depends on what your playing. Well recorded material you can have high peak values that you don't perceive as loud. Try using a digital SPL meter with a record function. I use one from time to time and have been surprised at peak levels recorded. Using an 85-90db average it's not at all uncommon for it the record 107-108 peaks as an example. I was just messing with my 2 channel system and was getting peaks in the 113db range. Ran out of power as well and when you work the numbers it was right where it should be. It was loud but not at all uncomfortable.
Lets face it most speakers are simply on the wrong side of the power curve. If you are not starting out close 100db 1 watt 1 meter you are going have a real tuff uphill climb if you can even get there.
Rob 🙂
Rybaudio said:
I think that your 5 18's might still be overkill. I only use bandpass designs tuned fairly narrow for max SPL output, but I get a really decent bass with 1 x 18, 2 x 15 subs and the 2 x 15 mains. I think that I can hit the levels that you noted with this. I'd have to do more calculating than I'm up for this late to be sure.
When you run a number of subs you tend to get close to a good average response that is nearly 1/8 space.
I don't believe I'm misstating reality. Clearly background noise and other factors relating to the environment of the listening area are factors in perception of loudness.
I also believe all the previous posters have valid points as well.
My perception of pleasantly loud music listening levels in my living room is as I described: In the 80's dB. In this environment I couldn't carry on a conversation unless we were talking quite loudly, and I'm not criticizing designing for more SPL's or listening at higher levels.
In my shop, the speakers will commonly measure up to low 90's dB @ 1 M with music playing. Standing at, and measuring the running table saw, I get 90 dB at start-up and 105dB while cutting a board. (Add 5dB to those numbers for the chopsaw!) So 20 years in this environment is not uncommon.
TTS is a physiological reaction to allow the ears to continue to function in a loud environment, and likely to protect the ears from permanent damage, much like the iris constricting in brighter light.
I was simply trying to suggest protecting our hearing as an audiologist would do, and designing appropriately for non-commercial applications. Many come here to learn about just that. I hear often about needs for high power and SPL's, but not from the truly experienced DIY'er building a home system, at least not here.
1000 Watt amps and "design target must be 125 - 130 dB at 1 meter" tempered with "All of these later posts are reasonable and if you want to subtract 10 dB for home listening thats fine" also works for me.
90 dB drivers, driven by 32 Watts gets you to 115dB, no?
Also, about my perception of a "sweet spot" threshold volume level for certain speakers-- I've changed my mind. The better ones, the ones designed for little or no distortion at higher SPL's don't suffer this effect. I suspect this what you have in mind for your design criteria, yes?
I also believe all the previous posters have valid points as well.
My perception of pleasantly loud music listening levels in my living room is as I described: In the 80's dB. In this environment I couldn't carry on a conversation unless we were talking quite loudly, and I'm not criticizing designing for more SPL's or listening at higher levels.
In my shop, the speakers will commonly measure up to low 90's dB @ 1 M with music playing. Standing at, and measuring the running table saw, I get 90 dB at start-up and 105dB while cutting a board. (Add 5dB to those numbers for the chopsaw!) So 20 years in this environment is not uncommon.
TTS is a physiological reaction to allow the ears to continue to function in a loud environment, and likely to protect the ears from permanent damage, much like the iris constricting in brighter light.
I was simply trying to suggest protecting our hearing as an audiologist would do, and designing appropriately for non-commercial applications. Many come here to learn about just that. I hear often about needs for high power and SPL's, but not from the truly experienced DIY'er building a home system, at least not here.
1000 Watt amps and "design target must be 125 - 130 dB at 1 meter" tempered with "All of these later posts are reasonable and if you want to subtract 10 dB for home listening thats fine" also works for me.
90 dB drivers, driven by 32 Watts gets you to 115dB, no?
Also, about my perception of a "sweet spot" threshold volume level for certain speakers-- I've changed my mind. The better ones, the ones designed for little or no distortion at higher SPL's don't suffer this effect. I suspect this what you have in mind for your design criteria, yes?
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