Approximate power at 1.34 ohms?

[psych0ticnemes1 5,000+ posts]

1200rms @ 1ohm... 750@ 2... how much at 1.34 you think? 1000 or so?

Thanks

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[jujumantb 10+ year member]

Thats nominal impedance... pretty pointless, you will have impedance rise with frequency and compression... etc. Taking an impedance to a hundredth decimal point is ridiculous //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif Not to mention you cant audibly hear a difference between a few hundered watts either way in that power range. Like people upgrading from 1000 watts to 1200 watts... WTF? //content.invisioncic.com/y282845/emoticons/eyebrow.gif.fe2c18d8720fe8c7eaed347b21ea05a5.gif

 

[psych0ticnemes1 5,000+ posts]

Thats nominal impedance... pretty pointless, you will have impedance rise with frequency and compression... etc. Taking an impedance to a hundredth decimal point is ridiculous //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif Not to mention you cant audibly hear a difference between a few hundered watts either way in that power range. Like people upgrading from 1000 watts to 1200 watts... WTF? //content.invisioncic.com/y282845/emoticons/eyebrow.gif.fe2c18d8720fe8c7eaed347b21ea05a5.gif

gotcha, thank you sir... i can tell a difference between 1200 and 750 on 2 300rms subs tho //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

i would think power handeling matters, 200watts to a 100rms woofer doesnt mean much, but to a 300rms woofer means poof lol

 

[jujumantb 10+ year member]

gotcha, thank you sir... i can tell a difference between 1200 and 750 on 2 300rms subs tho //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Well 2x the power gives you a hypothetical 3db gain. 6db is twice as loud, but most people hear more like 10db's as twice as loud. Say that would give you a 2db gain going from 750 to 1200, that, to most people, sounds like 1.2 times louder, not much at all! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Just something to put it all in perspective //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[helotaxi 5,000+ posts]

It's a logarithmic scale, 10dB is twice as loud by definition and takes just over 10x the power to get there.

 

[jujumantb 10+ year member]

It's a logarithmic scale, 10dB is twice as loud by definition and takes just over 10x the power to get there.

10dbs will double the sound pressure on your ear, but does that mean twice as loud to the ear? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Our ears are definitely not linear in this sense, very much frequency dependent. I dont like the usage of "by definition" when talking about loudness to the ear. Everyone is a bit different. 6dbs is the most accepted "twice as loud" measure to the ear.

 

[helotaxi 5,000+ posts]

Which is where the A and B weighting scales come in. They account for the frequency sensitivity of the ear. Yes everyone is different. So saying something is commonly accepted is falacious logic. That's like saying that jsut because the first 3 cars always run the red light, they are not breaking the law because it's commonly accepted to do so. When you say "twice as loud," you mean +10dB. It doesn't matter what influence psychosomatic perception has on the matter. That is why we have measuring devices. You can actually fool someone into believing that a sound got louder just by changing the frequency composition of the sound. That doesn't mean that the sound got louder. Loud has units. An increase of 10 units is a doubling of loudness. Saying that "to some people it might not" is irrelevant. Opinion does not cancel out physics.

 

[jujumantb 10+ year member]

Which is where the A and B weighting scales come in. They account for the frequency sensitivity of the ear. Yes everyone is different. So saying something is commonly accepted is falacious logic. That's like saying that jsut because the first 3 cars always run the red light, they are not breaking the law because it's commonly accepted to do so. When you say "twice as loud," you mean +10dB. It doesn't matter what influence psychosomatic perception has on the matter. That is why we have measuring devices. You can actually fool someone into believing that a sound got louder just by changing the frequency composition of the sound. That doesn't mean that the sound got louder. Loud has units. An increase of 10 units is a doubling of loudness. Saying that "to some people it might not" is irrelevant. Opinion does not cancel out physics.

Understood, there is always science vs perception.

An increase of 10 units is a doubling of loudness.

What exactly is doubling of loudness? Who is to say that? Is it a direct function of the decible scale? If so, how was the scale computed? Doubling of loudness just seems like such an ambiguous thing to me. I did a quick search and found a nice write-up by 'geoleman' in response to the question "what is twice as loud?"

Depends on the person

That's the most correct answer, actually... odd as that sounds.

What's confusing to most people when talking about decibels, are all the different contexts, and keeping them straight from one another:

1) human perception - psychology, most often based on surveys of laymen.

2) electrical measurements

3) actual sound pressure measurements

And I'm not saying I'm not forgetting some other possible contexts here.

About those contexts:

1) Human beings don't have any natural point of reference by which to judge how much of an increase represents "twice as much" sound.

It's not like a glass of water - you can see the glass, put a mental line on it where the water is currently at, and fill it roughly twice as much.. but even with that, if the glass had an odd shape - your accuracy would quickly go downhill.

And imagine if that was a glass filled with steam rather than water - how would you know when you pumped it with "twice as much" steam? It gets tricky.

With sound, you have no point of reference - and therefore, when put on the spot, people typically say (or rather - guess ) that when they believe the dB level has "doubled", they actually have typically overshot to the degree that the change in dB level is actually 10dB, not 6dB.

Of course - if you have a trained ear, with experience reconciling changes in sound level against an actual dB meter - you could probably identify 6dB pretty well every single time.

These surveys are not given to trained people such as these - these surveys are to make a point about how the average human has no point of reference - unless trained.

So - take this 10dB number with the right context in mind.

2) Simply put - doubling your electrical power (ie. going from 500 watts to 1000 watts) will NOT double your acoustical energy.

It takes a quadrupling of electrical power (ie. 500w to 2000w) to double your acoustical energy.

And, of course, that's assuming the sub can take a power increase of that degree...

And, of course, that's in an ideal world, not factoring in heat-based inefficiencies like power compression, that actually further decrease dB levels from that ideal, as you increase power... and therefore heat.

From earlier in this thread:

"No, twice as loud is a 3dB increase."

"No, that's twice the pressure, or something, not loudness to the human ear."

Doubling your amplifier power to your speaker (not counting things like power compression) ideally gain you 3dB.

Doubling your acoustical power happens when you have increased by 6dB.

In an ideal world, you'd have to quadruple your power to do that. And in this 'real world', you've got to do more than that, to overcome things like power compression.

3) Actual, measured sound pressure energy.

When a speaker moves in and out, it creates pressure fluctuations... really fast.

When it moves out, it compresses the air.

When it moves in, it rarefies the air... vacuum, if you will.

The greater the pressure difference between the compression and depressurized nodes in the air, the greater your SPL level.. "sound pressure level".

That's actual, measured sound pressure energy.

Really, all other contexts are discussed in reference to this...

"Can you believe it - even though doubling actually happens at 6dB levels of change, most people guessed closer to 10dB! This proves people don't have a natural means of judging that."

"Can you believe it - doubling the power input to a speaker doesn't double the displacement the speaker makes... we only measure about 3dB from that - it would take a fourfold increase to gain you the 6dB that you'd think would happen!"

etc.

Is there anything you would agree/disagree with here?

I've been around the community enough to totally respect your knowledge, you're one of the few guys I feel actually really knows what they're talking about. There are just so many different takes on this subject, I guess, I'd like to clear it all up.

 

[helotaxi 5,000+ posts]

Fair enough. geolemon knows the stuff even betere than I could imagine. Speaking of which, anyone heard from him in a while? Did the noobs irritate him to the point that he disappeared or what?

 

[jujumantb 10+ year member]

Fair enough. geolemon knows the stuff even betere than I could imagine. Speaking of which, anyone heard from him in a while? Did the noobs irritate him to the point that he disappeared or what?

I dunno, he still hangs out at CAF, doesnt post nearly as much though, can't blame him. As with you, when you get to a certain point of knowledge, I'd imagine the same ol' discussions about elementary shit gets pretty old. //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif