Speakers SPL is one of the terms of comparison between speakers and together with the frequency characteristic represent the only objective comparison mode until you can hear it............so a calibrated measurement is important.
So a speaker with a horrible FR but 90db efficient automatically is better than a flat FR but only 85 d?. I think you're misguided in your thinking. All SPL tells you is efficiency, nothing more. So if you have enough power it really is of no difference. The FR and on & off axis are the factors to focus on.
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So what are the difference between frequency characteristic and "Frequency Range" or " Frequency Response" ???
And what I ask here: on post 94 ???
Most would say a characteristic is more subjective, the FR with a calibrated mic gives an objective view of the sound with the given measurement parameters (distance (1M) and at what point of the speaker (typically tweeter axis)
Calibrated mic, software to capture and signal tones...google OMNI Mic, HOLM or REW. OmniMic is a complete package, the others are just FR capture software, but easy enough to get a mic and tones.
These would be used to get "raw" FR (without any XO) and used to design your XO. You will also need DATS to get in-box impedance because it varies with the signal.
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Calibrated mic, software to capture and signal tones...google OMNI Mic, HOLM or REW. OmniMic is a complete package, the others are just FR capture software, but easy enough to get a mic and tones.
These would be used to get "raw" FR (without any XO) and used to design your XO. You will also need DATS to get in-box impedance because it varies with the signal.
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Right back to my first response...why do you care about a calibrated measurement. A relative measurement will get you the FR and then tune by ear. Not difficult at all.
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Why do you think that were invented the measurement units?
To continue to make only comparative measurements?
30-40 years ago I would have understood but now no mitigating circumstances...........
To continue to make only comparative measurements?
30-40 years ago I would have understood but now no mitigating circumstances...........
So a quick Google search and you could have had everything you needed, but appears you want to be spoon fed.
1k tone signal, fed into your amp, connect your DMM to the speaker out and turn up the volume to get either 1v or 2.83v (1 watt) and set your mic up at 1 meter. Easy peasy, you have the "standard" metric for which speaker are touted and sold on, SPL at 1w/meter.
But I ask you again, what does that really tell you? It tells you speaeker A can play 87db with 1 watt and speaker B can play 85db. I have a 250 watt amp, so I can easily drive either speaker. The "real" decision is which one has a better FR curve and a the benign impedance so I don't blow up my amp.
Long way around to tell you that unless you are comparing your speaker to other speaker in a catalog...it doesn't matter to anyone but you.
1k tone signal, fed into your amp, connect your DMM to the speaker out and turn up the volume to get either 1v or 2.83v (1 watt) and set your mic up at 1 meter. Easy peasy, you have the "standard" metric for which speaker are touted and sold on, SPL at 1w/meter.
But I ask you again, what does that really tell you? It tells you speaeker A can play 87db with 1 watt and speaker B can play 85db. I have a 250 watt amp, so I can easily drive either speaker. The "real" decision is which one has a better FR curve and a the benign impedance so I don't blow up my amp.
Long way around to tell you that unless you are comparing your speaker to other speaker in a catalog...it doesn't matter to anyone but you.
Some times are enough to be only me.
My original question was if I need to use the RMS value or peak-peak value....for me is not very clear....
Thank you!
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I would use RMS, but might be difficult to get your DMM to settle down to exactly 2.83v especially a digital meter with auto ranging. For me its too much trouble, I just trust the woofer (or tweeter) manufacture specs on SPL, set my original test level on my amp to that level (during a sine wave test) and never touch the amplifier again. Then all the testing as long as it's at the same distance and same axis will show the comparable and directly relateable results.
I never trust completely the specifications from the supplier. I saw to many cases of wrong specifications.
And more, I do not use speaker in exactly the same conditions in which it was measured. I need to know what is the gain in my box.
I know you highlighted it, but seems like you didn't read it...I said SPL specs, not FR or impedance, doing testing on FR & T/S are highly advisable.
It comes back to why you are worried about a 1-2 db difference in SPL, that only comes into play when comparing a speaker you haven't heard in your own system/room.
I never said you shouldn't measure in the final listening location, just that knowing the SPL in that location really doesn't matter as long as the FR measures flat, sounds good to your ears and gets sufficiently loud enough, with low distortion.
A new location will change your upper-regions FR slightly due to diffraction (1k-20k), the only "real" influence will be BSC, the amount depends if you put it close to a wall or boundaries. There is no "gain" to a box, it will decrease by however much BSC there is in the lower octaves (up to 300-600 Hz), which needs to be accounted for in the XO design to regain a flat FR.
It comes back to why you are worried about a 1-2 db difference in SPL, that only comes into play when comparing a speaker you haven't heard in your own system/room.
I never said you shouldn't measure in the final listening location, just that knowing the SPL in that location really doesn't matter as long as the FR measures flat, sounds good to your ears and gets sufficiently loud enough, with low distortion.
A new location will change your upper-regions FR slightly due to diffraction (1k-20k), the only "real" influence will be BSC, the amount depends if you put it close to a wall or boundaries. There is no "gain" to a box, it will decrease by however much BSC there is in the lower octaves (up to 300-600 Hz), which needs to be accounted for in the XO design to regain a flat FR.
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