what does ohms and db mean?

[saprano]

im getting my system today(sig)and need to know what this means and does, the speakers im getting says it has an impendance of 4 to 6 ohms, and 89 db. and i just got my onkyo yesterday and it says any speaker with an impendance of 4 ohms or more but less than 6 i should set the impendance to 4 ohms. anyway i just need some info on whats the meaning of this stuff, and what does it do, thanks

[pedigree]

db is decibles and ohms is a unit of measure i think for electricity something like amps or volts... wiki it!

[fridge74]

ohms is the electric measure of resistance

[saprano]

Originally Posted by pedigree

db is decibles and ohms is a unit of measure i think for electricity something like amps or volts... wiki it!

yep your right i just wikied it, bassicly it has do power and volts- db http://en.wikipedia.org/wiki/Decibel ohms- http://en.wikipedia.org/wiki/Ohm thanks

[saprano]

oh one more question, what does bi-amping do?

[saprano]

Originally Posted by Strannix136

Bi-amping is usually used in PA applications. One amp is used to power the low frequencies and another amp is used for the mid and high frequencies.
Check out this link:
http://forum.ecoustics.com/bbs/messa...79/109419.html

thanks alot for that link!

[d_rob1031]

Just a heads up, don't let db make a decision for you. It takes 3db for the human ear to notice a difference in volume. In other words, if there's a tiny difference between 2, don't automatically think the higher is better, you won't notice a difference.

edit: gah, this take me back to college and circuits class. yuck.

[jomari]

in laymans terms...(mine i guess)

1. the ohms mentioned on a speaker, would be how much resistance your speakers have to a watt your receiver is sending. your reciever normally can 'push' speakers to a good level (100w for example) using a 8ohms. if the speakers ohms go lower (6-4 ohms) your receiver will have to work harder to 'push' sound into em. if your receiver isnt built for it, it would overload and/or shut down.
*** SCRATCH THIS***
***start of edit
for more information, i went to a fellow colleague who gave me more insightful meaning to this....

and i quote...
"Higher impedance means MORE resistance to the amp and the amp has to work harder to put out the same current. Lower impedance is LESS resistance and the amp isn't controlled at all while it puts out current and can go into overload from too much current coming out. High impedance is like a small water hose, low impedance is like a huge, fat water hose"

End of edit***

2. db used in speakers sense is the Sensitivity your speaker is to a current/sound produced by your receiver. the higher the db the greater the amount of sound produced by your speaker. if your reciever is set at 12db... or to make it simple... if its set at level 12, and your speaker is rated at sensitivity of 80db, you will hear a significant difference with a speaker set at level 12 with a sensitivity of 100db...the higher the sensitivity, the 'louder' the sound. remember, 'louder' doesnt always signify 'better'.

3. bi-amping, as others believe is quite a topic in the ht world. some believe there is a significant change in sound when you bi-amp your setup. bi-amping is when you are running separate amps for your bi-ampable speaker. (your speaker should have two set of connections in order to accomodate this)...
personal opinion? bi-amping/bi-wiring is only effective if your speakers can handle it, and you have a good set of amplifiers to push em. is it worth it? nope.

[MouseRider]

Totally, it isn't about "loud" or "raw power", it's about refinement and the ability to control the "loud" and the "power".

Ask any electrical engineer like d_rob

[jomari]

correct.

there are also other factors to consider, most of my colleagues would consider

source (receivers, pre/pro, tubes et al)
media (may it be in hd or not, turntables)
connectivity (speaker wiring, digital or analog, power amplification/cleaning)
and
ACOUSTICS (reverbations, echoing, et al)

i mention acoustics in all caps due to a number of people leave this as 10% of what their home theater should focus on. when my colleagues would mention that the room acoustics also plays a significant amount to improving the sound and color of your media room, even to boast it at a good 80% improvement. in the real world, we cant have acoustic panels, basstraps replacing our wifeys beautiful picture, or move the big useless vase in the corner to accomodate our needs.

[NJMetsFan]

Ohms mean resistance. The higher the ohms the higher the resistance, which means you get less power but its cleaner. Think of it like a filter, as you lower the ohms your power gets stonger but at a cost of sound quality.

If you have a receiver that outputs 100w @ 8 Ohms and an other one that outputs 100w @ 4 Ohms. The 100w @ 8 Ohms is better the power and signal is cleaner.

Db means decibal. Which is the level of the sound. Basically the higher the db the louder it is.

[Deciazulado]

actually 1 dB is a just noticeable diference, 3dB is a doubling of power and a noticeable amount, and 10dB (10 times the power) is a doubling of volume.

So if you want to have the music play at double the volume you have to go from 1 watt to 10 watts in the same speakers (or 10 watts to 100, or 100 to a thousand, etc.)

Going from 100 watts per channel to 120 watts per channel won't even increase the volume 1 dB for example.

Ohms is resistance.

So if you have an 8 ohm speaker that sounds 89 dBs loud at 1 meter with a 2.83 volt input (~1 watt at 8 ohms) from an amplifier, you'd get 92 dBs from that same 2.83volt signal from the amplifier if the resistance was 4 ohms (~2 watts at 4 ohms):

2.83 volts squared is 8, divided into 8 ohms = 1 watt
2.83 volts squared is 8, divided into 4 ohms = 2 watt
2 watts/1 watt= 2

log of 2 = 3.01 dBs

Knowing this you can calculate all sorts of things for example if you have 8 ohm speakers that output 80 dBs at 10 feet with 1 watt you'll need 320 watts per channel to reach the 105 dBs per channel max vol spec for theaters (85 dB reference + 20 dB headroom).


Same thing for video resolution/noise. Kodak states to notice a difference in resolution ability on a film emulsion it has to record 1 dB more resolution. Double the negative area and you have half the grain at the same magnificatioion (3dBs less grain) etc. BD's about 2 to 3dB better that Hd DVD on average all else being equal.

[jomari]

deciazulado just went on a technical rampage here! hehehe. great comparison points tho...

[Dadds]

this thread has some of the best info i have seen in awhile

nice job everyone

[musicman1999]

Originally Posted by Deciazulado

actually 1 dB is a just noticeable diference, 3dB is a doubling of power and a noticeable amount, and 10dB (10 times the power) is a doubling of volume.

So if you want to have the music play at double the volume you have to go from 1 watt to 10 watts in the same speakers (or 10 watts to 100, or 100 to a thousand, etc.)

Going from 100 watts per channel to 120 watts per channel won't even increase the volume 1 dB for example.

Ohms is resistance.

So if you have an 8 ohm speaker that sounds 89 dBs loud at 1 meter with a 2.83 volt input (~1 watt at 8 ohms) from an amplifier, you'd get 92 dBs from that same 2.83volt signal from the amplifier if the resistance was 4 ohms (~2 watts at 4 ohms):

2.83 volts squared is 8, divided into 8 ohms = 1 watt
2.83 volts squared is 8, divided into 4 ohms = 2 watt
2 watts/1 watt= 2

log of 2 = 3.01 dBs

Knowing this you can calculate all sorts of things for example if you have 8 ohm speakers that output 80 dBs at 10 feet with 1 watt you'll need 320 watts per channel to reach the 105 dBs per channel max vol spec for theaters (85 dB reference + 20 dB headroom).


Same thing for video resolution/noise. Kodak states to notice a difference in resolution ability on a film emulsion it has to record 1 dB more resolution. Double the negative area and you have half the grain at the same magnificatioion (3dBs less grain) etc. BD's about 2 to 3dB better that Hd DVD on average all else being equal.

Ten DB is not a doubling of volume, nor is 3 DB a doubling of power. It takes double the power to increase the volume by 3 DB and every further 3 DB increase requires double the power, example 1 watt=78db, 2 watt=81db, 4 watt=84db, 8 watt=87db, 16 watt=90db, 32watt=93db, 64watt=96db, you get where i am going, so doubling the volume 156db would require thousands of watts.Of course 156db you could not stay in the room and your speakers would explode.

bill

[NJMetsFan]

Originally Posted by Dadds

this thread has some of the best info i have seen in awhile

nice job everyone

I noticed your from South Jersey. I was raised and graduated from Egg Harbor Twp. Its about 10 miles west from A.C.

[saprano]

wow guys thanks again, i just came back from my local audio store in new york, i picked up 2 pro 800 monitors, thats all i can afford right know. then later i get 2 more, and a pro 1000 sub. these speakers have a impendance of 4 to 6 ohms so im all good right? and my onkyo has 100watts of power. and deciazulado.. your a monster. everybody thanks for the info.

[Pilam69]

Originally Posted by NJMetsFan

Ohms mean resistance. The higher the ohms the higher the resistance, which means you get less power but its cleaner. Think of it like a filter, as you lower the ohms your power gets stonger but at a cost of sound quality.

If you have a receiver that outputs 100w @ 8 Ohms and an other one that outputs 100w @ 4 Ohms. The 100w @ 8 Ohms is better the power and signal is cleaner.

Db means decibal. Which is the level of the sound. Basically the higher the db the louder it is.

In car audio the lower the ohm rating the better the quality of the sound and the higher quality of amplifier you will need to run it. I am fairly certain the same concept applies to home audio as well (I really can't imagine why it would be different). An amp that can handle a 2-4 ohm load will be pushing significantly more wattage than an 8 ohm amplifier (which requires better components, bigger capaciters, etc.), this doesn't mean the sound is dirtier by any stretch of the imagination. GENERALLY, the better the speaker the lower the ohm load it will handle.

[saprano]

Originally Posted by Deciazulado

actually 1 dB is a just noticeable diference, 3dB is a doubling of power and a noticeable amount, and 10dB (10 times the power) is a doubling of volume.

So if you want to have the music play at double the volume you have to go from 1 watt to 10 watts in the same speakers (or 10 watts to 100, or 100 to a thousand, etc.)

Going from 100 watts per channel to 120 watts per channel won't even increase the volume 1 dB for example.

Ohms is resistance.

So if you have an 8 ohm speaker that sounds 89 dBs loud at 1 meter with a 2.83 volt input (~1 watt at 8 ohms) from an amplifier, you'd get 92 dBs from that same 2.83volt signal from the amplifier if the resistance was 4 ohms (~2 watts at 4 ohms):

2.83 volts squared is 8, divided into 8 ohms = 1 watt
2.83 volts squared is 8, divided into 4 ohms = 2 watt
2 watts/1 watt= 2

log of 2 = 3.01 dBs

Knowing this you can calculate all sorts of things for example if you have 8 ohm speakers that output 80 dBs at 10 feet with 1 watt you'll need 320 watts per channel to reach the 105 dBs per channel max vol spec for theaters (85 dB reference + 20 dB headroom).


Same thing for video resolution/noise. Kodak states to notice a difference in resolution ability on a film emulsion it has to record 1 dB more resolution. Double the negative area and you have half the grain at the same magnificatioion (3dBs less grain) etc. BD's about 2 to 3dB better that Hd DVD on average all else being equal.

dame! i had read this like 10 times to compleatly understand it your a beast, where did you learn all this? your not a HAL 9000 or you? lol thanks again

[saprano]

Originally Posted by jomari

correct.

there are also other factors to consider, most of my colleagues would consider

source (receivers, pre/pro, tubes et al)
media (may it be in hd or not, turntables)
connectivity (speaker wiring, digital or analog, power amplification/cleaning)
and
ACOUSTICS (reverbations, echoing, et al)

i mention acoustics in all caps due to a number of people leave this as 10% of what their home theater should focus on. when my colleagues would mention that the room acoustics also plays a significant amount to improving the sound and color of your media room, even to boast it at a good 80% improvement. in the real world, we cant have acoustic panels, basstraps replacing our wifeys beautiful picture, or move the big useless vase in the corner to accomodate our needs.

what do you mean by cleaning? you mean the amp?