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#41
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Is SPL additive?
"Eeyore" wrote in message ... INRI wrote: "Eeyore" wrote in message INRI wrote: The theoretical sound pressure level from 2 speakers @ 100db each would be 106db The theoretical sound power level for 2 speakers @ 100db each would be 103db Make you mind up what it is will you ? Pressure levels are measured in 20log p1/p2 which doubles for every 6db and power levels are measured in 10log pw1/pw2 and doubles every 3db The Sound Pressure reference Level is 0.0002ubar or (2x10E-5N/m*2) You haven't answered the question have you ? Graham Yes |
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#42
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
INRI wrote: "Eeyore" wrote in message INRI wrote: "Eeyore" wrote in message INRI wrote: The theoretical sound pressure level from 2 speakers @ 100db each would be 106db The theoretical sound power level for 2 speakers @ 100db each would be 103db Make you mind up what it is will you ? Pressure levels are measured in 20log p1/p2 which doubles for every 6db and power levels are measured in 10log pw1/pw2 and doubles every 3db The Sound Pressure reference Level is 0.0002ubar or (2x10E-5N/m*2) You haven't answered the question have you ? Yes No you haven't. It can't be both 103dB AND 106dB at the same time. I suggest you read this...... http://en.wikipedia.org/wiki/Sound_power_level And this http://en.wikipedia.org/wiki/Sound_pressure_level Graham |
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#43
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
"Eeyore" wrote in message ... INRI wrote: "Eeyore" wrote in message INRI wrote: "Eeyore" wrote in message INRI wrote: The theoretical sound pressure level from 2 speakers @ 100db each would be 106db The theoretical sound power level for 2 speakers @ 100db each would be 103db Make you mind up what it is will you ? Pressure levels are measured in 20log p1/p2 which doubles for every 6db and power levels are measured in 10log pw1/pw2 and doubles every 3db The Sound Pressure reference Level is 0.0002ubar or (2x10E-5N/m*2) You haven't answered the question have you ? Yes No you haven't. It can't be both 103dB AND 106dB at the same time. I suggest you read this...... http://en.wikipedia.org/wiki/Sound_power_level And this http://en.wikipedia.org/wiki/Sound_pressure_level Graham Its the same as I stated, POWER is not PRESSURE these are two distinct quantities and show two different ratiometric levels. |
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#44
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On Tue, 3 Jul 2007 12:19:18 +0100, "INRI"
wrote: "Eeyore" wrote in message ... INRI wrote: "Eeyore" wrote in message INRI wrote: "Eeyore" wrote in message INRI wrote: The theoretical sound pressure level from 2 speakers @ 100db each would be 106db The theoretical sound power level for 2 speakers @ 100db each would be 103db Make you mind up what it is will you ? Pressure levels are measured in 20log p1/p2 which doubles for every 6db and power levels are measured in 10log pw1/pw2 and doubles every 3db The Sound Pressure reference Level is 0.0002ubar or (2x10E-5N/m*2) You haven't answered the question have you ? Yes No you haven't. It can't be both 103dB AND 106dB at the same time. I suggest you read this...... http://en.wikipedia.org/wiki/Sound_power_level And this http://en.wikipedia.org/wiki/Sound_pressure_level Graham Its the same as I stated, POWER is not PRESSURE these are two distinct quantities and show two different ratiometric levels. No, you have it wrong. A sound pressure level of 103dB is 103dB greater SPL than .0002uBar. That is the constant, if you like. You use the 10log or 20log ratios to derive power or pressure from that figure. The sound level is *not* 103 or 106 depending on how you calculate it. d -- Pearce Consulting http://www.pearce.uk.com |
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#45
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
In article , Salmon Egg wrote:
On 7/2/07 7:16 PM, in article jkiii.3950$Of2.1615@trnddc06, "Karl Uppiano" wrote: No, I was taking issue with Salmon Egg's electrical statements about the amount of power drawn from constant voltage vs. constant current [sic.] amplifiers. I thought the statements were wrong, but I wanted to phrase it in such a way as to not provoke a flame war. I am afraid that by walking on eggshells to avoid attack, I must have confused a lot of people. I also wanted to avoid a flame war. That is why I did not respond. Unless there was some blunder I missed on my part, I was correct. Putting two speakers in series for a low impedance output amplifier, reduces total power output to half of what it would be for a single speaker. Double the impedance; half the current and half the power. Lets put 4 drivers in series. Same output. 1/4 th power, will handle 4 times the power of one. When your building stacks, these things are very important to know. You can put 4 woofers close together and basically get this improvement in efficiency and power handling. You can also feed 4 woofers into a common exit port, which produces very good phase addition. greg |
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#46
Posted to rec.audio.tech
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Is SPL additive?
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#47
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Eeyore wrote in
: DaveC wrote: OP here... I guess I left out a fewe details: The speakers will be separated by a few inches, aimed identically (they are driver/horn setups), and driven from separate identical amplifiers. Amplifier inputs will be identical. It looks like, leaving out phase cancellations, the total SPL will be 106 dB. No. 103dB. Graham I disagree, the doubling of drive by using two amps gives 3dB, plus the increase due to the beaming of the two drivers is another 3 dB so 106dB is the output. -- Bob Quintal PA is y I've altered my email address. -- Posted via a free Usenet account from http://www.teranews.com |
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#48
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On 3 jul, 10:38, (Don Pearce) wrote:
On Tue, 03 Jul 2007 01:29:11 -0700, bert stoltenborg wrote: Parallel: +3 dB for extra driver +3 dB for impedance /2 = 106 dB That is double-counting. It is simply +3 for the extra driver so 103dB. Serial: +3 dB for extra driver -3 dB for impedance x 2 =100 dB Again double counting. The power has halved, so it is -3dB or 97dB. Finally, it all depends on the frequency. At low frequencies it is 103dB, as above. At high frequencies the added driver will change the directional pattern of the speaker, narrowing the beam. At the highest frequencies the beam width will be halved, which adds an extra 3dB to the on-axis response, but reduces it off axis. So the on-axis response will be 106dB at high frequencies. Remember: To much knowledge can drive you insane Too little is happy land. d -- Pearce Consultinghttp://www.pearce.uk.com 2 amps = 2 x power = +3dB impedance / 2 = 2 x power = +3dB 2 speakers = + 3dB 2 speakers in serial = 2 x impedance = -3dB Or you are re-inventing speaker theory :-) Introducing all kinds of variables shows you know your stuff, but when I ask about fundamentals you should start with fundamentals. Air absorption at large distances, refraction by atmospheric effect etc are beyond the initial question, if you ask me. But I'm clearly an idiot. :-) |
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#49
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On Tue, 03 Jul 2007 06:11:58 -0700, bert stoltenborg
wrote: 2 amps = 2 x power = +3dB impedance / 2 = 2 x power = +3dB Sure - but those are just two ways of saying the same thing. You can't add together those 3dBs and make it 6dB. It is just 3dB. 2 speakers = + 3dB 2 speakers in serial = 2 x impedance = -3dB And you are doing it again for the series case. Two speakers only make +3dB if they are each carrying the same power. In this case they are not. They are each carrying one quarter of the power (half the voltage x half the current, in fact) of the single speaker. Together they add to half the power, hence -3dB. There is nothing to cancel. Or you are re-inventing speaker theory :-) Introducing all kinds of variables shows you know your stuff, but when I ask about fundamentals you should start with fundamentals. Air absorption at large distances, refraction by atmospheric effect etc are beyond the initial question, if you ask me. Quite so - which is why I did not introduce them. But the geometric effects of two speakers side by side are most certainly within the scope of the question, particularly when they have an effect that is as large (at high frequencies) as the simple electrical effect. But I'm clearly an idiot. :-) Nope - you just need to sort out a slight muddle. d -- Pearce Consulting http://www.pearce.uk.com |
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#50
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On 3 jul, 15:20, (Don Pearce) wrote:
On Tue, 03 Jul 2007 06:11:58 -0700, bert stoltenborg wrote: 2 amps = 2 x power = +3dB impedance / 2 = 2 x power = +3dB Sure - but those are just two ways of saying the same thing. You can't add together those 3dBs and make it 6dB. It is just 3dB. 2 speakers = + 3dB 2 speakers in serial = 2 x impedance = -3dB And you are doing it again for the series case. Two speakers only make +3dB if they are each carrying the same power. In this case they are not. They are each carrying one quarter of the power (half the voltage x half the current, in fact) of the single speaker. Together they add to half the power, hence -3dB. There is nothing to cancel. Or you are re-inventing speaker theory :-) Introducing all kinds of variables shows you know your stuff, but when I ask about fundamentals you should start with fundamentals. Air absorption at large distances, refraction by atmospheric effect etc are beyond the initial question, if you ask me. Quite so - which is why I did not introduce them. But the geometric effects of two speakers side by side are most certainly within the scope of the question, particularly when they have an effect that is as large (at high frequencies) as the simple electrical effect. But I'm clearly an idiot. :-) Nope - you just need to sort out a slight muddle. d -- Pearce Consultinghttp://www.pearce.uk.com I wasn't specific aiming at you, Don, more in general. A lot of answers in this thread are correct. I tried to see it from the practical side; somebody is hanging two speakers to an amp, either in parallel or in series. The poster should prolly redefine the question (as so often). :-) Maybe the |
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#51
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On 3 jul, 15:34, bert stoltenborg wrote:
On 3 jul, 15:20, (Don Pearce) wrote: On Tue, 03 Jul 2007 06:11:58 -0700, bert stoltenborg wrote: 2 amps = 2 x power = +3dB impedance / 2 = 2 x power = +3dB Sure - but those are just two ways of saying the same thing. You can't add together those 3dBs and make it 6dB. It is just 3dB. 2 speakers = + 3dB 2 speakers in serial = 2 x impedance = -3dB And you are doing it again for the series case. Two speakers only make +3dB if they are each carrying the same power. In this case they are not. They are each carrying one quarter of the power (half the voltage x half the current, in fact) of the single speaker. Together they add to half the power, hence -3dB. There is nothing to cancel. Or you are re-inventing speaker theory :-) Introducing all kinds of variables shows you know your stuff, but when I ask about fundamentals you should start with fundamentals. Air absorption at large distances, refraction by atmospheric effect etc are beyond the initial question, if you ask me. Quite so - which is why I did not introduce them. But the geometric effects of two speakers side by side are most certainly within the scope of the question, particularly when they have an effect that is as large (at high frequencies) as the simple electrical effect. But I'm clearly an idiot. :-) Nope - you just need to sort out a slight muddle. d -- Pearce Consultinghttp://www.pearce.uk.com I wasn't specific aiming at you, Don, more in general. A lot of answers in this thread are correct. I tried to see it from the practical side; somebody is hanging two speakers to an amp, either in parallel or in series. The poster should prolly redefine the question (as so often). :-) Maybe the Of course when you have a source and add the same source, you get + 3 dB increase in spl. |
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#52
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On Tue, 03 Jul 2007 06:34:28 -0700, bert stoltenborg
wrote: The poster should prolly redefine the question (as so often). :-) Right. But that is easy to say in hindsight. He will either sort the wheat from the chaff for himself - although if he really needed to ask in the first place, he probably isn't in a position to do that. Otherwise, he may gather some of what has occurred he and, as you say, re-pose the question with some of the blanks filled in. d -- Pearce Consulting http://www.pearce.uk.com |
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#53
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
In article . com, bert stoltenborg wrote:
On 3 jul, 10:38, (Don Pearce) wrote: On Tue, 03 Jul 2007 01:29:11 -0700, bert stoltenborg wrote: Parallel: +3 dB for extra driver +3 dB for impedance /2 = 106 dB That is double-counting. It is simply +3 for the extra driver so 103dB. Serial: +3 dB for extra driver -3 dB for impedance x 2 =100 dB Again double counting. The power has halved, so it is -3dB or 97dB. Finally, it all depends on the frequency. At low frequencies it is 103dB, as above. At high frequencies the added driver will change the directional pattern of the speaker, narrowing the beam. At the highest frequencies the beam width will be halved, which adds an extra 3dB to the on-axis response, but reduces it off axis. So the on-axis response will be 106dB at high frequencies. Remember: To much knowledge can drive you insane Too little is happy land. d -- Pearce Consultinghttp://www.pearce.uk.com 2 amps = 2 x power = +3dB impedance / 2 = 2 x power = +3dB 2 speakers = + 3dB 2 speakers in serial = 2 x impedance = -3dB Or you are re-inventing speaker theory :-) Introducing all kinds of variables shows you know your stuff, but when I ask about fundamentals you should start with fundamentals. Air absorption at large distances, refraction by atmospheric effect etc are beyond the initial question, if you ask me. But I'm clearly an idiot. SPL and power always get confused. Two speakers should sound twice as loud as one. But the ears do not respond that way, but they should. SPL is doubled. In designing an MTM array, I first read the paper in Speaker Builder over 20 years ago. I thought Joseph DeAppolito was wrong, but that was the first time I got enlightned to SPL levels. If you take two 90 dB sensitivity midranges in the MTM configuration, you need a 96 dB efficient tweeter to match those midranges, without any padding. greg |
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#54
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On Sun, 01 Jul 2007 04:55:11 GMT, DaveC wrote:
A basic question from an inquisitive commoner. If two identical speakers with identical drive signal, placed side by side, each output 100dB, what is the total output dB from the 2 speakers? Thanks. Ask Svante. |
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#55
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On 3 jul, 15:48, (GregS) wrote:
In article . com, bert stoltenborg wrote: On 3 jul, 10:38, (Don Pearce) wrote: On Tue, 03 Jul 2007 01:29:11 -0700, bert stoltenborg wrote: Parallel: +3 dB for extra driver +3 dB for impedance /2 = 106 dB That is double-counting. It is simply +3 for the extra driver so 103dB. Serial: +3 dB for extra driver -3 dB for impedance x 2 =100 dB Again double counting. The power has halved, so it is -3dB or 97dB. Finally, it all depends on the frequency. At low frequencies it is 103dB, as above. At high frequencies the added driver will change the directional pattern of the speaker, narrowing the beam. At the highest frequencies the beam width will be halved, which adds an extra 3dB to the on-axis response, but reduces it off axis. So the on-axis response will be 106dB at high frequencies. Remember: To much knowledge can drive you insane Too little is happy land. d -- Pearce Consultinghttp://www.pearce.uk.com 2 amps = 2 x power = +3dB impedance / 2 = 2 x power = +3dB 2 speakers = + 3dB 2 speakers in serial = 2 x impedance = -3dB Or you are re-inventing speaker theory :-) Introducing all kinds of variables shows you know your stuff, but when I ask about fundamentals you should start with fundamentals. Air absorption at large distances, refraction by atmospheric effect etc are beyond the initial question, if you ask me. But I'm clearly an idiot. SPL and power always get confused. Two speakers should sound twice as loud as one. But the ears do not respond that way, but they should. SPL is doubled. In designing an MTM array, I first read the paper in Speaker Builder over 20 years ago. I thought Joseph DeAppolito was wrong, but that was the first time I got enlightned to SPL levels. If you take two 90 dB sensitivity midranges in the MTM configuration, you need a 96 dB efficient tweeter to match those midranges, without any padding. greg You prolly loose a couple of dB's in the X-over.... :-) sorry, couldn't resist. |
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#56
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On Jul 3, 1:21 am, Salmon Egg wrote:
On 7/2/07 8:22 PM, in article , "Eeyore" Thus if the peakers are isolated and shielded, you double the power to 10.3bel. 10.3 bel ? Are you intentionally obfuscating ? Possibly. What is wrong with using bels instead of decibels? Well, other than the fact that if you search the relevant literature on acoustics, and if you search these and related newsgroups, the number of times you will see "bel" used as you have totals about one over the last couple of decades. I know of not a single sound level meter that displays in "bels" instead of :decibels," do you? I know of no speaker manufacturer that states their products' sensitivity figures in "bels" instead of "decibels," do you? I know of no calibrated audio faders, attenuators, amplifiers and such that state their gain or loss in terms of "bels" instead of "decibels," do you? When is the last time you saw a filter slope specified in "bels per octave?" I have never seen a CD player with a dynamic range specified as "9.6 bels," have you? When is the last time you went to a hardware store and bought a 1/48 foot 240 thread per inch machine screw? How about a blank panel for your 0.5277777 yard rack enclosure? Or took your kids temperature and got really frightened when it was 310.15 K? Most assuredly, numerically, 10.3 bels is perfectly valid. So is 310.15 K for a normal body temperature 98.6F or 37C, and your 19" rack cabinet is indeed 0.5277777 yards wide. So what? What problem did you hope to solve by ignoring the lingua franca of the domain in which you were speaking? |
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#57
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
INRI wrote: "Eeyore" wrote INRI wrote: "Eeyore" wrote INRI wrote: "Eeyore" wrote INRI wrote: The theoretical sound pressure level from 2 speakers @ 100db each would be 106db The theoretical sound power level for 2 speakers @ 100db each would be 103db Make you mind up what it is will you ? Pressure levels are measured in 20log p1/p2 which doubles for every 6db and power levels are measured in 10log pw1/pw2 and doubles every 3db The Sound Pressure reference Level is 0.0002ubar or (2x10E-5N/m*2) You haven't answered the question have you ? Yes No you haven't. It can't be both 103dB AND 106dB at the same time. I suggest you read this...... http://en.wikipedia.org/wiki/Sound_power_level And this http://en.wikipedia.org/wiki/Sound_pressure_level Its the same as I stated, POWER is not PRESSURE these are two distinct quantities and show two different ratiometric levels. You simply haven't a clue have you. From that comment I'm sure you can't have read it in detail. The ratiometrric aspect 'comes out in the wash' because you're measuring 2 different things. It certainly doesn't make 103dB = 106dB. dB in this example is short for dB SPL anyway (not dBW). Most ppl lazily don't bother putting SPL after the dB. For any given signal the dB change is the same whether you measure it by power or pressure/voltage. It *has* to be by definition or dBs would be worthless. Graham |
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#58
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Don Pearce wrote: "INRI" wrote: "Eeyore" wrote in message INRI wrote: "Eeyore" wrote in message You haven't answered the question have you ? Yes No you haven't. It can't be both 103dB AND 106dB at the same time. I suggest you read this...... http://en.wikipedia.org/wiki/Sound_power_level And this http://en.wikipedia.org/wiki/Sound_pressure_level Its the same as I stated, POWER is not PRESSURE these are two distinct quantities and show two different ratiometric levels. No, you have it wrong. A sound pressure level of 103dB is 103dB greater SPL than .0002uBar. That is the constant, if you like. You use the 10log or 20log ratios to derive power or pressure from that figure. The sound level is *not* 103 or 106 depending on how you calculate it. Whatever happened to decent education ? Graham |
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#59
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
GregS wrote: Lets put 4 drivers in series. Why ? Same output. 1/4 th power, will handle 4 times the power of one. When your building stacks, these things are very important to know. You can put 4 woofers close together and basically get this improvement in efficiency Utter and complete nonsense. I suppose you believe in 'free energy' and perpetual motion too ? You do not get 'something for nothing', nor is it even remotely relevant whether speakers are in series, parallel or driven separately from individual amps. Graham |
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#60
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Bob Quintal wrote: Eeyore wrote in DaveC wrote: OP here... I guess I left out a fewe details: The speakers will be separated by a few inches, aimed identically (they are driver/horn setups), and driven from separate identical amplifiers. Amplifier inputs will be identical. It looks like, leaving out phase cancellations, the total SPL will be 106 dB. No. 103dB. I disagree, the doubling of drive by using two amps gives 3dB, plus the increase due to the beaming of the two drivers is another 3 dB so 106dB is the output. Beaming on what axis. The OP never stated where he was measuring btw. Graham |
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#61
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
bert stoltenborg wrote: 2 amps = 2 x power = +3dB impedance / 2 = 2 x power = +3dB That's 'double counting'. Graham |
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#62
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
bert stoltenborg wrote: Of course when you have a source and add the same source, you get + 3 dB increase in spl. Thank you ! Why didn't you say that in the first place ? The OP asked a simple enough question and a bunch of right idiots had to over-complicate and obfuscate about it. Graham |
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#63
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
In article , Eeyore wrote:
GregS wrote: Lets put 4 drivers in series. Why ? Same output. 1/4 th power, will handle 4 times the power of one. When your building stacks, these things are very important to know. You can put 4 woofers close together and basically get this improvement in efficiency Utter and complete nonsense. I suppose you believe in 'free energy' and perpetual motion too ? You do not get 'something for nothing', nor is it even remotely relevant whether speakers are in series, parallel or driven separately from individual amps. You would probably say, horn enclosures-drivers cannot create more efficiency too, right?? So how do horn enclosures create more efficiency?? Same way as multiple drivers!!!!! greg |
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#64
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Eeyore wrote in
: Bob Quintal wrote: Eeyore wrote in DaveC wrote: OP here... I guess I left out a fewe details: The speakers will be separated by a few inches, aimed identically (they are driver/horn setups), and driven from separate identical amplifiers. Amplifier inputs will be identical. It looks like, leaving out phase cancellations, the total SPL will be 106 dB. No. 103dB. I disagree, the doubling of drive by using two amps gives 3dB, plus the increase due to the beaming of the two drivers is another 3 dB so 106dB is the output. Beaming on what axis. On Axis. Nobody really cares about off axis. People have gotten all kefuffled about comb filtering, but it will not occur at all on axis, and only becomes noticeable when the difference in distance from the focal point of each radiator is close to an odd multiple of 1/2 wavelength of the frequency being radiated. The OP never stated where he was measuring btw. Do you measure input impedance at the output of an amp? some things are understood when filtered through common sense. Graham -- Bob Quintal PA is y I've altered my email address. -- Posted via a free Usenet account from http://www.teranews.com |
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#65
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
GregS wrote: Eeyore wrote: GregS wrote: Lets put 4 drivers in series. Why ? Same output. 1/4 th power, will handle 4 times the power of one. When your building stacks, these things are very important to know. You can put 4 woofers close together and basically get this improvement in efficiency. Speaker 'stacks' do not put 4 drivers in series btw. That kind of speaker went out of widespread use about 30 yrs ago btw. Utter and complete nonsense. I suppose you believe in 'free energy' and perpetual motion too ? You do not get 'something for nothing', nor is it even remotely relevant whether speakers are in series, parallel or driven separately from individual amps. You would probably say, horn enclosures-drivers cannot create more efficiency too, right?? So how do horn enclosures create more efficiency?? The horn is an 'acoustic transformer' that better matches the (high) acoustic impedance of the driver to the load (the auditorium) resulting in greater power transfer. Same way as multiple drivers!!!!! No, they're *completely* different. In any event, a horn is (usually) a single driver. If you know that little about the subject you ought to shut the **** up. Graham |
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#66
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Eeyore wrote in
: Bob Quintal wrote: Eeyore wrote The OP never stated where he was measuring btw. Do you measure input impedance at the output of an amp? some things are understood when filtered through common sense. What's that got to do with anything ? It's common sense to talk about on axis for discussions of SPL increase due to beamforming/coupling, not beside or behind the speaker array. Direct on axis measurements have relatively little to do with what a speaker may sound like in a room / auditorium. So you face your speakers to the ceiling ??? In short, 2 speakers will NOT sound 6dB louder for most listeners. They will be 3dB louder. So you think John Meyer, the people at JBL, the folks at Renkus- Heinz. Howard Tremayne and many others are all spouting bullcrap. In a proper installation, the sound field over the primary listening area does increase six(6) dB when using a pair of close-coupled speakers versus a single speaker. I got news for you boy. Read the engineering documents. You don't have to weep, but you won't be able to deny the facts. Or you can accept the fact that when I set up a system and had one cabinet on each side of the stage go offline, the level at FOH dropped 6 dB. I measured it live, and the ambient sound mic on my video recorder still drops 6 dB at the point where the drunk tripped over the AC supply for phase B. -- Bob Quintal PA is y I've altered my email address. -- Posted via a free Usenet account from http://www.teranews.com |
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#67
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Bob Quintal wrote: Eeyore wrote The OP never stated where he was measuring btw. Do you measure input impedance at the output of an amp? some things are understood when filtered through common sense. What's that got to do with anything ? Direct on axis measurements have relatively little to do with what a speaker may sound like in a room / auditorium. In short, 2 speakers will NOT sound 6dB louder for most listeners. They will be 3dB louder. Graham |
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#68
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
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#69
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Salmon Egg wrote: "DaveC" wrote: OP here... I guess I left out a fewe details: The speakers will be separated by a few inches, aimed identically (they are driver/horn setups), and driven from separate identical amplifiers. Amplifier inputs will be identical. It looks like, leaving out phase cancellations, the total SPL will be 106 dB. Sorry. It depends on the frequency. If the frequency is high enough so that the measured sound field is primarily radiated field, The level will have peaks of 10.6B 106dB. while the average over space will be only 10.3B. 103dB. Yes. And that's the *important* one. The *average*. What may happen at some very specific point on axis is of almost no consequence whatever to a typical listener.. And get over your stupid use of bels will you ? Are you deliberately trying to confuse the OP ? Graham |
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#70
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
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#71
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Salmon Egg wrote: On 7/2/07 11:43 PM, in article , "Eeyore" wrote: The statements are broadly contradictory. Either the acoustic radiation impedance is a small contributor to the driver impedance as a whole (which means that there can only be an even smaller effect from coupling ) or it isn't. This will be my last response on this point to Eeyore. Oh la-di -dah ! Sounds to me like you're backing away from your original position. At low frequency, the acoustic radiation impedance of an ordinary speaker is going to be small compared to the total speaker impedance. The radiation impedance will get smaller as the frequency lowers. Small as that radiation impedance may get, it is only the electrical current flowing through that impedance that tells how much electrical power gets converted into acoustic power. No. The elctrical current tells you nothing about the conversion efficiency. How on earth did you arrive at that conclusion ? Graham |
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#72
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Salmon Egg wrote: "Eeyore" wrote: You may argue that speakers are not antennas, but the many principles of wave propagation transfer between electromagnetism and acoustics and water waves. I agree entirely on that point. Another reason you can't just add SPLs as if they were voltages in a circuit. Graham |
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#73
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
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#75
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On Tue, 03 Jul 2007 11:38:23 -0700, Salmon Egg
wrote: I want to break the mold. There is nothing wrong with using bels as units rather than decibels! Look, 2 barn megaparsecs make one teaspoon (British, not American), but I think we will continue using the teaspoon in cookery. Please stick with normal nomenclature - it really does make life easier for everybody. Just write letters to The Times in green ink if you really feel the need to be a rebel. d -- Pearce Consulting http://www.pearce.uk.com |
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#76
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
Salmon Egg wrote: " wrote: What problem did you hope to solve by ignoring the lingua franca of the domain in which you were speaking? I want to break the mold. There is nothing wrong with using bels as units rather than decibels! Nor is there anything good about it. Would you choose to measure length in decimetres ? Graham |
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#77
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
So the on-axis response will be 106dB at high frequencies.
OP here... f ~ 25-30 KHz. Not for listening pleasure. Pure sine wave input for experiment. "Target distance" is ~ 30 meters outdoors. Thanks, -- DaveC This is an invalid return address Please reply in the news group |
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#78
Posted to alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
On Tue, 03 Jul 2007 20:12:32 GMT, DaveC wrote:
So the on-axis response will be 106dB at high frequencies. OP here... f ~ 25-30 KHz. Not for listening pleasure. Pure sine wave input for experiment. "Target distance" is ~ 30 meters outdoors. Thanks, Is that 25kHz to 30kHz or 25Hz to 30kHz? d -- Pearce Consulting http://www.pearce.uk.com |
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#79
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
DaveC wrote:
OP here... I guess I left out a fewe details: The speakers will be separated by a few inches, aimed identically (they are driver/horn setups), and driven from separate identical amplifiers. Amplifier inputs will be identical. It looks like, leaving out phase cancellations, the total SPL will be 106 dB. No. 103dB. Double the power is a 3dB rise (3.01dB if youwant to be predantic). geoff |
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#80
Posted to alt.sci.physics,alt.sci.physics.acoustics,rec.audio.tech
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Is SPL additive?
INRI wrote:
Its the same as I stated, POWER is not PRESSURE these are two distinct quantities and show two different ratiometric levels. And he is not doubling the pressure, he is doubling the power. So 3dB geoff |
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