quick audio question

[cubdh23]

For a car speaker, when it says 90DB w/m for sensitivity

Which is louder, more powerful 90db w/m or 93dbw/m

I know 3 db is half but sometimes i get confused as to which way that number points.
thanks which is better? which is 2 times as powerful? just based on sensitivity.

 

[Russlk]

3 dB is a factor of 2 in power. +3 dB is double, -3 dB is 1/2.

 

[audioguru]

The speaker that is rated at 93db/1W/1m should sound 3dB louder than the 90dB/1W/1m speaker. But it might just peak at only one frequency to get the better measurement. To make an accurate comparison, the spec's should say it was measured with wideband pink noise, not just a single frequency.
If they have the same flat frequency response, you might not even notice the difference unless you switch them quickly back and forth, because your hearing is logarithmic and a 3dB difference (twice or half the power) sounds almost the same. A 10dB difference (10 times or 1/10th the power) sounds twice or half as loud.
"My 200W amp sounds twice as loud as your 100W amp". No it doesn't, they sound almost the same (only a 3dB difference).
When an amplifier reaches clipping or tries to go louder, this rule is no longer valid because distortion sounds a lot louder than pure sound (and you can kiss your fragile tweeters goodbye).

 

[Juglenaut]

I wish everyone played music in a car within its threshold.

I have a co-worker that plays his music as load as it can be and it distorts something fierce. He listens to mine which is 10% lower than clipping threshold it sound very clean and crisp at low to lower mid ranges on a sub-sonic filter and he thinks mine sucks because it not loud enough.

His system runs mono at 2 ohms, 2 12inch subs in a sealed box, a sony 800 watt amp. I think it pushes RMS at 400watts or so at 2 ohm.

My system runs at 6 ohm mono, 2 10inch subs Audiobahn Alum DVC in a divider vented box, a kicker ZR360 rated 567watt at 4ohm stereo RMS at roughly 360W, Mine has alot of headroom without distorting, does not sound as loud, but my signal to noise is alot better than his. If i drop this badboy of an amp to 1.66/1.50 ohm it would peak out at close to 1200 watts RMS over 720W, I have 2 kicker amps that I bought just before they phased them out and are 1 ohm stable, They both have 1999 power supplies.

I will just have to hook my speakers up at 1.50 ohm and show him why I run it the way I do.

 

[audioguru]

Hi Juglenaut,
My son has a high powered boom-boom system in his car. He couldn't wait for me to build him one so he bought an expensive 10" sub-woofer with a huge magnet and pretty-good specs already mounted in a sealed box with see-thru plexiglass and a mirror inside. He didn't like the sound of it so we took it inside for me to measure. It didn't make any sound below about 80Hz! He couldn't believe it as I slowly swept the frequencies lower. Then I did the same with a cheap 8" speaker I built and it went all the way down to about 30Hz loudly and clearly.
BTW, his sub-woofer buzzed like crazy at about 150Hz! A couple of long screws in a corner fixed it. We EQ'd it to make it go down to about 50Hz.

My GM Pontiac car came with 20 ohm 5 X 7's in the back pumping out a whopping 2W each. When I replaced them with 4 ohm 6 X 9's I get about 14 Watts cleanly (it would be advertised at least 50 Whats!).
The radio/CD player has AVC so I can crank it up to max volume and beyond and it gets to a certain very loud level and doesn't go any louder, with NO distortion. Well, it does distort but only on the 1st beat or two (AVC attack time).
I don't like the AVC. I can hear it breathing (with bad breath!) on certain tunes. The background sound or melody disappears during each beat. :lol:

 

[Juglenaut]

Are you running the 6x9 with full pass or mid??

Sounds weird to me as to why the spendy speaker wouldn't go lower, mabey the speakers specs didn't tune into that box. I do know that some speakers have to be within tolerance especially for a band-pass box. High roll or extended movement subs don't like band-pass boxes to much as they are tuned for the extention, speakers that yield good responses at a smaller extentions like sealed boxes and most times require the least amount of volume for a good sound. Also I had a few experiences where extended movement subs actually destroyied band pass boxes.

I need new 6x9's as they distort because the subs are right under them, they are some sony ones that push mids like crap. Subs face up, ports pointing towards rear.

When I got my subs I had to look up the QTS and such to figure out port length, putting some poly fill helped balance the volume in the box. The alum10 didn't like to be sealed at 1.2(1 cubic with speaker) cubic so I ported it.

I have always liked Infinity's perfect kappa series subs and components, I once had two 12inch, two 10's perfect kappas, and 5 kicker amps, and reference series comps. My rear window blew out once and my front windshield cracked from my old system. That system rocked as did many of my friends systems.

My old school friend ran those Old cerwin vaga adjustible cone subwoofer-speakers strokers, man was it $%^ loud, he ran 4000 watts RMS and could feel the ground literally vibrate. **broken link removed**

Oh and the reason I run mine at 6ohms is because my car can't handle the current draw right now as the same alt has been in it for a long time and has been abused. I am now a poor school guy that has no money lol, I had to sell alot of my stuff but held onto a few amps.

 

[audioguru]

Hi Juglenaut,
I'm running my 6 X 9s full-pass, with the entire trunk as their box they go down nice and low. With only 14W each, they don't over-excurt.

My son's subwoofer was obviously designed for looks, not sound. The sealed box is way too small for the 10" driver, it resonates at about 100Hz, like a Bose "subwoofer". With EQ boosting its low end so it's flat to 50Hz, the car's cabin gain makes it sound pretty good. I can hear it about half a block away (windows up, 2 blocks windows down).

My son and yourself have way too much sound pressure in your cars. Soon your hearing will be shot but it probably is already. When AM and FM both sound the same, you're in trouble.
I'm fairly old but my hearing is still pretty good because I've protected it all my life (except once, when I was listening to radio interference from an 18" sub up close, someone turned on the music). :lol:

 

[Juglenaut]

I did forget to mention I used to live in the middle of nowhere so sound traveles far.

I actually test sound/air density in my car and it only goes up a few pints at 2/3's volume. That with my current system, I never blaired my stereo unless I was outside of it or protected my ears and vacated the car. I only treshhold mine to 2/3's in the car, and comfort listening is perfered at 1/2 volume. My deck is set for 0 bass, my EQ is set for neutral boost with no RCA pre/post gain. My rear 6x9 suck just because they are really old, and are only 50 watt, I high pass them at 250hz.

My current system is set up for easy listening, and no harsh pressure is felt on the ear drums, believe me I no what you mean.

My hearing is at 100% still and I just had a 100% physical.

 

[audioguru]

I actually test sound/air density in my car and it only goes up a few pints

Hi Juglenaut,
He, he. You're on a Brit site talking about pints? You probably drank even more beer during your tests.

... at 2/3's volume..., ... at 1/2 volume...

The position of your volume control is meaningless unless we know at what setting the amplifier clips, and its "audio-taper" ratio (10%, 20%?) at half setting.

My rear 6x9 suck just because they are really old, and are only 50 watt

Car sound equipment manufacturers rate speakers in Whats, not Watts.
The difference is where you position the decimal point. I agree that a 5W speaker sucks.

My hearing is at 100% still and I just had a 100% physical.

I had my hearing tested once, and when they stopped at 3KHz I asked, "Is that all, what about the other nearly three octaves?"

When I was young my parents took me to the opera at the concert hall. The concert hall's horn tweeters sounded awful, like the PA at a ball game.
The concert hall had an "ultrasonic" motion detector alarm system that was on all the time, and I heard it so loud that I couldn't stand it. My parents and anyone else I asked including my young sister couldn't hear it. Yes, I am a macho guy.
He, he.

 

[David Bridgen]

For a car speaker, when it says 90DB w/m for sensitivity

Which is louder, more powerful 90db w/m or 93dbw/m

I know 3 db is half but sometimes i get confused as to which way that number points.
thanks which is better? which is 2 times as powerful? just based on sensitivity.

cubdh23,

you should by now, thanks to audioguru's answer, realise that the specifications you mention are a measure of efficiency. The higher firgure meaning more power is converted to sound.

Regarding your confusion about decibel notation, the first few lines of this may help you:

https://www.davidbridgen.com/watts.htm


And regarding the mention in a couple of posts of watts r.m.s. all readers may find this of interest:

https://www.davidbridgen.com/watts.htm

 

[David Bridgen]

It has taken me until now to spot that the first URL given in the previous post is wrong.

It should be https://www.davidbridgen.com/dbnotation.htm