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Speaker Ratings
- Thread starter TravTrav
- Start date
billfitzmaurice
Commercial User
- Sep 15, 2004
- 16,860
- 278
- 76
- Disclosures
- Owner, Bill Fitzmaurice Loudspeaker Design
RMS and continuous are interchangeable. Everything else should be ignored. For that matter even RMS/continuous doesn't tell you what you need to know. Displacement limited power does, but only Barefaced reveals that.
- Feb 16, 2008
- 21,240
- 23,634
- Disclosures
- John K Custom Basses
Loads of info here, explained in simple terms....
http://barefacedbass.com/technical-information.htm
http://barefacedbass.com/technical-information.htm
Here's some more info ~
Watts matter - for example, when replacing a light bulb in a lamp fixture you will see a warning sticker that reads something like CAUTION: To reduce the risk of fire use a 60 WATT type A or smaller lamp. If watts didn’t matter there wouldn’t be any fire risk or warning stickers on lamps.
And, no a light bulb is not a speaker but this is another example of wattage mattering (common sense too).
And this is what Eminence engineers say ~
Power handling
This specification is very important to transducer selection. Obviously, you need to choose a loudspeaker that is capable of handling the input power you are going to provide. <snip> The ideal situation is to choose a loudspeaker that has the capability of handling more power than you can provide lending some headroom and insurance against thermal failure. <snip>
(Speaker size matters too)
Generally speaking, the number one contributor to a transducer’s power rating is its ability to release thermal energy. This is affected by several design choices, but most notably voice coil size, magnet size, venting, and the adhesives used in voice coil construction. Larger coil and magnet sizes provide more area for heat to dissipate, while venting allows thermal energy to escape and cooler air to enter the motor structure. Equally important is the ability of the voice coil to handle thermal energy. Eminence is renowned for its use of proprietary adhesives and components that maximize the voice coil’s ability to handle extreme temperatures. Mechanical factors must also be considered when determining power handling. A transducer might be able to handle 1,000W from a thermal perspective, but would fail long before that level was reached from a mechanical issue such as the coil hitting the back plate, the coil coming out of the gap, the cone buckling from too much outward movement, or the spider bottoming on the top plate. The most common cause of such a failure would be asking the speaker to produce more low frequencies than it could mechanically produce at the rated power. Be sure to consider the suggested usable frequency range and the Xlim parameter in conjunction with the power rating to avoid such failures. <snip>
http://www.eminence.com/support/understanding-loudspeaker-data/
----------------------------------------
Picking the right speakers for your bass amplifier.
Over powering a speaker can damage it and a impedance mismatch can damaged an amplifier. See Eminence‘s webpage http://www.eminence.com/support/understanding-loudspeaker-data and look under “POWER HANDLING”. And Myers Sound “Making Sense of Amplifier Power Ratings” [Invalid or Expired Link Removed]
Power - the ideal situation is to choose a loudspeaker that has the capability of handling more power than you can provide lending some headroom and insurance against thermal failure. If you don’t know how much power a speaker cab can handle, slowly turn up the bass amp volume until the speaker starts to sound bad, then turn down the bass or volume until it sounds good.
DO NOT connect speakers with a total power handling capacity below the power output rating of
your amplifier. If your amplifier is rated at 400 watts at 4 ohms, then the combined power handling of your
speaker enclosures should be 400 watts RMS or higher at 4 ohms. [Invalid or Expired Link Removed]
Ohms - make sure the speaker cab impedance meets the bass amp requirements. Look on the back of your bass amp and note the required speaker load (ohms) and make sure the impedances of your speakers match. DO NOT connect speakers with a combined total impedance that is below the minimum rating of your amplifier. Doing so may cause damage to your gear. Using speakers with a total impedance above the minimum power rating of your amplifier is safe. See http://www.eminence.com/support/wiring-diagrams
Speaker stacking. 1dB is considered the least amount of SPL gain the human ear can hear and 3dB is considered the least useable amount of SPL in the real world by most (with some opposition) and it takes about 10dB to double the volume (SPL). See http://www.animations.physics.unsw.edu.au/jw/dB.htm If you have a 100 watt amp with one 12" speaker and you add another incidental 12" speaker you will get the magic 3dB increase. You would have the same SPL as a 200 watt amp with one 12" speaker (if the driver isn’t already maxed out). To get the next 3dB increase you need to double the speakers again so you would need four incidental 12" speakers. Having 4 speakers will give you a 6dB increase in SPL compared to 1 speaker. Then it gets more complex. If you double the 4 speakers to 8 speakers there isn’t a 9dB increase in SPL as compared to one speaker like you’d think, instead you only a 6dB increase compared to one speaker because phase cancellation comes into play. The distance between the speakers causes the sound to reach your ears from some of the speakers at a different time and this has the effect of canceling some sound so more speakers are better up to a point. Drivers, enclosures, power, impedance, etc all play a role in the SPL. Also checkout the Bass Guitar Magazine articles by Barefaced http://barefacedbass.com/bgm-columns.htm expressly http://barefacedbass.com/technical-information/Volume-displacement.htm
Power - peak, continuous, etc.
http://en.wikipedia.org/wiki/Audio_power
Speaker size does matter when it comes to moving air (SPL) - cone area.
How to calculate cone area.
Cone area = pi x (r x r)
pi = 3.14 r = radius of sub
# 8” 10” 12” 15” 18”
-----------------------------------------------------
1 50 78 113 176 254
2 100 157 226 353 508
3 150 235 339 530 763
4 201 314 452 706 1017
5 251 392 565 883 1272
6 301 471 678 1060 1526
7 351 549 791 1236 1781
8 402 628 904 1413 2035
NOTE: All numbers rounded down to the nearest inch.
Drivers, enclosures, power, etc all are factors - and speaker size does matter when it comes to moving air (SPL) and shouldn’t be downplayed. And remember the cab is built around the speaker and not the other way around.
Watts matter - for example, when replacing a light bulb in a lamp fixture you will see a warning sticker that reads something like CAUTION: To reduce the risk of fire use a 60 WATT type A or smaller lamp. If watts didn’t matter there wouldn’t be any fire risk or warning stickers on lamps.
And, no a light bulb is not a speaker but this is another example of wattage mattering (common sense too).
And this is what Eminence engineers say ~
Power handling
This specification is very important to transducer selection. Obviously, you need to choose a loudspeaker that is capable of handling the input power you are going to provide. <snip> The ideal situation is to choose a loudspeaker that has the capability of handling more power than you can provide lending some headroom and insurance against thermal failure. <snip>
(Speaker size matters too)
Generally speaking, the number one contributor to a transducer’s power rating is its ability to release thermal energy. This is affected by several design choices, but most notably voice coil size, magnet size, venting, and the adhesives used in voice coil construction. Larger coil and magnet sizes provide more area for heat to dissipate, while venting allows thermal energy to escape and cooler air to enter the motor structure. Equally important is the ability of the voice coil to handle thermal energy. Eminence is renowned for its use of proprietary adhesives and components that maximize the voice coil’s ability to handle extreme temperatures. Mechanical factors must also be considered when determining power handling. A transducer might be able to handle 1,000W from a thermal perspective, but would fail long before that level was reached from a mechanical issue such as the coil hitting the back plate, the coil coming out of the gap, the cone buckling from too much outward movement, or the spider bottoming on the top plate. The most common cause of such a failure would be asking the speaker to produce more low frequencies than it could mechanically produce at the rated power. Be sure to consider the suggested usable frequency range and the Xlim parameter in conjunction with the power rating to avoid such failures. <snip>
http://www.eminence.com/support/understanding-loudspeaker-data/
----------------------------------------
Picking the right speakers for your bass amplifier.
Over powering a speaker can damage it and a impedance mismatch can damaged an amplifier. See Eminence‘s webpage http://www.eminence.com/support/understanding-loudspeaker-data and look under “POWER HANDLING”. And Myers Sound “Making Sense of Amplifier Power Ratings” [Invalid or Expired Link Removed]
Power - the ideal situation is to choose a loudspeaker that has the capability of handling more power than you can provide lending some headroom and insurance against thermal failure. If you don’t know how much power a speaker cab can handle, slowly turn up the bass amp volume until the speaker starts to sound bad, then turn down the bass or volume until it sounds good.
DO NOT connect speakers with a total power handling capacity below the power output rating of
your amplifier. If your amplifier is rated at 400 watts at 4 ohms, then the combined power handling of your
speaker enclosures should be 400 watts RMS or higher at 4 ohms. [Invalid or Expired Link Removed]
Ohms - make sure the speaker cab impedance meets the bass amp requirements. Look on the back of your bass amp and note the required speaker load (ohms) and make sure the impedances of your speakers match. DO NOT connect speakers with a combined total impedance that is below the minimum rating of your amplifier. Doing so may cause damage to your gear. Using speakers with a total impedance above the minimum power rating of your amplifier is safe. See http://www.eminence.com/support/wiring-diagrams
Speaker stacking. 1dB is considered the least amount of SPL gain the human ear can hear and 3dB is considered the least useable amount of SPL in the real world by most (with some opposition) and it takes about 10dB to double the volume (SPL). See http://www.animations.physics.unsw.edu.au/jw/dB.htm If you have a 100 watt amp with one 12" speaker and you add another incidental 12" speaker you will get the magic 3dB increase. You would have the same SPL as a 200 watt amp with one 12" speaker (if the driver isn’t already maxed out). To get the next 3dB increase you need to double the speakers again so you would need four incidental 12" speakers. Having 4 speakers will give you a 6dB increase in SPL compared to 1 speaker. Then it gets more complex. If you double the 4 speakers to 8 speakers there isn’t a 9dB increase in SPL as compared to one speaker like you’d think, instead you only a 6dB increase compared to one speaker because phase cancellation comes into play. The distance between the speakers causes the sound to reach your ears from some of the speakers at a different time and this has the effect of canceling some sound so more speakers are better up to a point. Drivers, enclosures, power, impedance, etc all play a role in the SPL. Also checkout the Bass Guitar Magazine articles by Barefaced http://barefacedbass.com/bgm-columns.htm expressly http://barefacedbass.com/technical-information/Volume-displacement.htm
Power - peak, continuous, etc.
http://en.wikipedia.org/wiki/Audio_power
Speaker size does matter when it comes to moving air (SPL) - cone area.
How to calculate cone area.
Cone area = pi x (r x r)
pi = 3.14 r = radius of sub
# 8” 10” 12” 15” 18”
-----------------------------------------------------
1 50 78 113 176 254
2 100 157 226 353 508
3 150 235 339 530 763
4 201 314 452 706 1017
5 251 392 565 883 1272
6 301 471 678 1060 1526
7 351 549 791 1236 1781
8 402 628 904 1413 2035
NOTE: All numbers rounded down to the nearest inch.
Drivers, enclosures, power, etc all are factors - and speaker size does matter when it comes to moving air (SPL) and shouldn’t be downplayed. And remember the cab is built around the speaker and not the other way around.
