Audio power summing
Don't think so. 🙄 That's dB SPL being summed there, not dB as measured in Volts output (dBU etc.)
OK.... 🙄
Now walk me thru this so i can follow along , by doubling the cone area by adding the second speaker we pick up how much dB... ?
Now we double the power to the speakers , we pick up how much dB?
Wanna really get going , what about room gain, changes dem deer anechoic numbers huh ...............
Now walk me thru this so i can follow along , by doubling the cone area by adding the second speaker we pick up how much dB... ?
Now we double the power to the speakers , we pick up how much dB?
Wanna really get going , what about room gain, changes dem deer anechoic numbers huh ...............
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I measured a similar SPL one day when my wife complained about the noise.
Moreover, when I turned my amp off I noticed she was speaking louder than that.
Ciao,
Massimo
audio summing
Hi a.wayne, I think I'm O/T but unless you talk specifically of a mono source, there is little apart from bass and centre program that need sum to the extent that a theoretical 6dD quadrupling would indicate. Certainly, bass increases dramatically but I don't hear such significant increases in mid and HF, other than you would expect from two equal level audio sources. Actually, cancellation by phase differences between drivers also comes into the picture as we increase frequency.
Then, that's just me and other, wiser heads may hear differently.
😀
Hi a.wayne, I think I'm O/T but unless you talk specifically of a mono source, there is little apart from bass and centre program that need sum to the extent that a theoretical 6dD quadrupling would indicate. Certainly, bass increases dramatically but I don't hear such significant increases in mid and HF, other than you would expect from two equal level audio sources. Actually, cancellation by phase differences between drivers also comes into the picture as we increase frequency.
Then, that's just me and other, wiser heads may hear differently.
😀
High power amps can make transients sound 'very satisfying' when played loud!😀
But then if you have neighbours close to you or one lives in an apartment playing very loud 'could' lead to various problems.
I find that using a speaker with 88dB/watt sensitivity and a 100 watt per channel amp , I can get enough volume in a space about 4500 cu feet that is VERY loud and that cannot be sustained for long as it can start affecting one's hearing. You cannot make conversation easily at that level.
However some music track have a very wide dynamic range and most of the time stay in the average level range but hit peaks that are very loud. Like say Bach or Bust or Beethoven or Bust by Dan Dorsey. Other music discs can appear to be too loud at this volume setting as the average levels are quite high.
I also have a LM1875 amp running with +/-25 volt (unloaded) supplies .
This goes pretty loud too ! transients do sound nice on this one too and it actually sounds better at lower level than the 100 watt amp.
If I had to choose just ONE amp and had to get rid of all the others,
I'd probably pick one that gives me about 20 to 25 watts per channel.......like the TDA2050/LM1875 . Speakers would have to be about 88dB/W or more.
Speakers that can go down reasonably low would be great as one can avoid using a sub. A 7 inch bass driver would be ideal I think. But these are variables that are hard to fix. Some speakers with 5 inch drivers and properly placed sound satisfying(!) too.
But then if you have neighbours close to you or one lives in an apartment playing very loud 'could' lead to various problems.
I find that using a speaker with 88dB/watt sensitivity and a 100 watt per channel amp , I can get enough volume in a space about 4500 cu feet that is VERY loud and that cannot be sustained for long as it can start affecting one's hearing. You cannot make conversation easily at that level.
However some music track have a very wide dynamic range and most of the time stay in the average level range but hit peaks that are very loud. Like say Bach or Bust or Beethoven or Bust by Dan Dorsey. Other music discs can appear to be too loud at this volume setting as the average levels are quite high.
I also have a LM1875 amp running with +/-25 volt (unloaded) supplies .
This goes pretty loud too ! transients do sound nice on this one too and it actually sounds better at lower level than the 100 watt amp.
If I had to choose just ONE amp and had to get rid of all the others,
I'd probably pick one that gives me about 20 to 25 watts per channel.......like the TDA2050/LM1875 . Speakers would have to be about 88dB/W or more.
Speakers that can go down reasonably low would be great as one can avoid using a sub. A 7 inch bass driver would be ideal I think. But these are variables that are hard to fix. Some speakers with 5 inch drivers and properly placed sound satisfying(!) too.
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Stand-alone sub units can be useful in positioning them in the room ,to overcome stationary waves . by just lifting it at about 1 meter above the floor, you 'jump over' some issues related to 'wall-dip'.
I would say i probably need around 500 Watts at peak program with an 88dbs sensitive
speaker.
My neighbors never complain:they like what i play and i do high energy listening at sensible hours...
speaker.
My neighbors never complain:they like what i play and i do high energy listening at sensible hours...
I guess whatever works for each one's 'situation' is the optimum. So there are no rules or die hard facts that one should follow. Bottom line is that no matter how loud you play ( ignoring neighbours and others complaints !) the spl at your ear drum is all that matters. If it's too loud it will kill the sensitivity and frequency response of one's hearing system if indulged in for too long.
The louder it goes the faster is the irreparable damage.
Many members here on this forum have already mentioned how their own hearing has been compromised by being exposed to very high spl in their earlier days ! I'd keep this in mind when turning up the wick ( especially on headphones !). I'd like to be able to hear enough into the HF to hear tinkling bells , cymbals etc. when I'm old !😀
Did I just say WHEN I'm old ?
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Nice pointers.
But 500 Watt peaks is what a 50 Watts ordinary listening comes to.
You can attach in parallel a meter to the speaker / amp and see how the
power escalates on sudden peaks or specific Hz-loudness combinations...
I use big speakers and i listen at 6 meters away-so it's 25/250 Watts tops
for the usual 3 meter away listening point.
If you do the math it is less than 108 db's for peaks and probably less than
90 dbs for the standard listening levels----in high energy program!
I can't listen to ZZTop any lower!
But 500 Watt peaks is what a 50 Watts ordinary listening comes to.
You can attach in parallel a meter to the speaker / amp and see how the
power escalates on sudden peaks or specific Hz-loudness combinations...
I use big speakers and i listen at 6 meters away-so it's 25/250 Watts tops
for the usual 3 meter away listening point.
If you do the math it is less than 108 db's for peaks and probably less than
90 dbs for the standard listening levels----in high energy program!
I can't listen to ZZTop any lower!
this is a quite different topic to listening to stereo with a pair of speakers.
When replaying bass and to a lesser extent lower mid, then one can combine drivers to gain in LF output. But that is over a very restricted frequency range.
Combine 2off 8inch drivers in one cabinet, such that the driver edges are just touching.
The centre to centre distance of that pair of drivers is 8inches.
The overall width across the two adjacent drivers is ~14inches.
The SPL from the twin driver arrangement starts to falls off when the wavelength of frequency is approximately equal to double the 14inch width. And has reached the -3dB when the wavelength has dropped to double the 8inch C/C dimension. So our pair will reinforce each other below 1100ft/s *12 / 14inch*2 ~ 500Hz and will provide no reinforcement (-3dB) at ~800Hz and continues to fall at at ~ 6dB/octave until the lobing of interference starts to become prominent.
If you increase the speaker C/C distance from 8inch to 80inch, the -3dB frequency has gone down to ~80Hz.
This is what Ian was talking about
You can test this by disconnecting one of the stereo pair. The low bass appears to drop more than the remainder of the frequency range. And it comes back when you reconnect. Some of this effect is accounted for my the Fletcher Munchen phenomenon, but our brain is quite good at correcting for this when volume is reduced. We are familiar with bass/mid ratios at different volumes and our "hearing" tells tells us to hear the full audio bandwidth. This implies that I am not a believer in tone controls and worse LF lift that increases as volume reduces.
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I know it's not hifi (though they're not bad), I find a pair of 98dB@1w speakers sufficient, driven by 50w per speaker. Turn it up, put on the ACDC. Gives 121dB peaks at 1m. It's certainly enough for a small band situation.
For more normal listening (I only break out the larger speakers for special occasions), my Fostexes never pass 100dB. Mainly because they go into cone break-up before that.
Chris
For more normal listening (I only break out the larger speakers for special occasions), my Fostexes never pass 100dB. Mainly because they go into cone break-up before that.
Chris
Hi a.wayne, I think I'm O/T but unless you talk specifically of a mono source, there is little apart from bass and centre program that need sum to the extent that a theoretical 6dD quadrupling would indicate. Certainly, bass increases dramatically but I don't hear such significant increases in mid and HF, other than you would expect from two equal level audio sources. Actually, cancellation by phase differences between drivers also comes into the picture as we increase frequency.
Then, that's just me and other, wiser heads may hear differently.
This is very simply Ian, turn off one channel while listening, only a 3db drop.?
A. W.
you are misquoting Ian.
He clearly said theoretical 6dB quadrupling. (actually "theoretical 6dD quadrupling").
Why do you change this to 3dB?
you are misquoting Ian.
He clearly said theoretical 6dB quadrupling. (actually "theoretical 6dD quadrupling").
Why do you change this to 3dB?
A.W.
you are confusing the doubling of power delivered and the bass reinforcement of doubling the Sd.
I can't tell if you are deliberating doing this to stir things up.
you are confusing the doubling of power delivered and the bass reinforcement of doubling the Sd.
I can't tell if you are deliberating doing this to stir things up.
Hello Andrew ,
Here they are and no Low freq doesn't fall of more than the other freq range as you previously stated, well maybe on very poor speakers they do..
Here they are and no Low freq doesn't fall of more than the other freq range as you previously stated, well maybe on very poor speakers they do..
OK.... 🙄
Now walk me thru this so i can follow along , by doubling the cone area by adding the second speaker we pick up how much dB... ?
Now we double the power to the speakers , we pick up how much dB?
Wanna really get going , what about room gain, changes dem deer anechoic numbers huh ...............
a. wayne, you are obviously not accepting the explanations offered, so state your
objections clearly here or in a PM or start another thread if you have evidence to
support them. Sure, splice any replies together and you can get conflict from anyone.
So let's cut to the previous model:
2 stereo speaker boxes are not on the same baffle, nor fed with the same signal nor
within close proximity so that reinforcement can optimally occur.
That's quite a problem for upper bass, mid and HF, right?
Lower bass is usually still within the proximity criterion, however, and does add further
to levels up to 6dB SPL above the reference output. That's quadrupling the SPL!
For practical purposes, the remainder of the output can be considered to only increase
the total sound output by simple addition of the SPL or power, doubling and hence increasing
them by 3dB. That is double the power.
Andrew has explained the physical model adequately and it's clear to anyone working
with speakers that there is frequency dependence on reinforcement such that only
wavelengths much greater than driver spacing can consistently reinforce to the
theoretical 6dB max. The remainder of the speaker output simply adds such that an
average 3dB SPL increase in the listening area is experienced. Obviously, that is also
similar to cranking the volume knob up to a level of twice the power output, a 3dB
increase, right?
Note: That may not be related to a VU meter on a preamp displaying say 3dB volume
increase. since dBU, dBV and dBm are all defined differently for different purposes.
You got all the references to 3 dB difference? That's 3dB power, not voltage, like one
speaker plays Trance at 85 dB av. and the other speaker is playing Techno at 85 dB
av. The total av. SPL = 88 dB. Disregard bass since it will chaotically interfere with
measurement and is not (yet) in dispute.
objections clearly here or in a PM or start another thread if you have evidence to
support them. Sure, splice any replies together and you can get conflict from anyone.
So let's cut to the previous model:
2 stereo speaker boxes are not on the same baffle, nor fed with the same signal nor
within close proximity so that reinforcement can optimally occur.
That's quite a problem for upper bass, mid and HF, right?
Lower bass is usually still within the proximity criterion, however, and does add further
to levels up to 6dB SPL above the reference output. That's quadrupling the SPL!
For practical purposes, the remainder of the output can be considered to only increase
the total sound output by simple addition of the SPL or power, doubling and hence increasing
them by 3dB. That is double the power.
Andrew has explained the physical model adequately and it's clear to anyone working
with speakers that there is frequency dependence on reinforcement such that only
wavelengths much greater than driver spacing can consistently reinforce to the
theoretical 6dB max. The remainder of the speaker output simply adds such that an
average 3dB SPL increase in the listening area is experienced. Obviously, that is also
similar to cranking the volume knob up to a level of twice the power output, a 3dB
increase, right?
Note: That may not be related to a VU meter on a preamp displaying say 3dB volume
increase. since dBU, dBV and dBm are all defined differently for different purposes.
You got all the references to 3 dB difference? That's 3dB power, not voltage, like one
speaker plays Trance at 85 dB av. and the other speaker is playing Techno at 85 dB
av. The total av. SPL = 88 dB. Disregard bass since it will chaotically interfere with
measurement and is not (yet) in dispute.
This whole thing is ridiculous!
Andrew, you said by adding a second speaker (as in from mono to stereo) the db increase is 3db:
Sound familiar?
A Wayne said NO, it's 6db
Way to bury a thread in a steaming load of fermenting....😡
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