what does ohms and db mean?

[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

[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.

[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

[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.

[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

[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.

[jomari]

Originally Posted by Pilam69

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.

correct. its not just in the car industry but in general. the problem is that there are only a few manufacturers of 4ohm even 2ohm speakers out there, to cater to the large market of 'home theater enthusiast' right now. the 'audiophiles' are the ones who normally purchase these, and mostly listen to stereo material. an amp that can push 2-4-6 ohms can 'generally' push 8ohms speakers easily, thus more expensive.

what looks good on paper, doesnt necessarily mean its true.

[frenchglen]

Wooooaaaah I'm all spec'd out.

[richteer]

Originally Posted by Pilam69

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.

With respect, that's total hogwash!

The "ohm rating" (which is the measurement of how much resistance a given speaker presents as a load) has got absolutely nothing whatsoever to do with sound quality. There are good high impedence speakers, and crappy low impedence ones. I'll take my 8 ohm Spendor SP1/2s over some crappy 4 ohm speaker any day of the week!

It is true that a speaker that has a lower impedence is usually harder to drive than one with a higher one, because it'll require more current to drive it and crappyy amps tend to have crappy PSUs and hence can't supply the required current.

Impedence and sensitivity (the db figure the OP refered to) together give an indication of how "hard" a speaker is to drive. A speaker with a low impendence (say, 1 ohm) and low sensitivity (~80 db) would be an absolute ***** to drive. For an example of this type of speaker, look no further than the Apogee Scintilla (RIP)...

[Pilam69]

Originally Posted by richteer

With respect, that's total hogwash!

The "ohm rating" (which is the measurement of how much resistance a given speaker presents as a load) has got absolutely nothing whatsoever to do with sound quality. There are good high impedence speakers, and crappy low impedence ones. I'll take my 8 ohm Spendor SP1/2s over some crappy 4 ohm speaker any day of the week!

It is true that a speaker that has a lower impedence is usually harder to drive than one with a higher one, because it'll require more current to drive it and crappyy amps tend to have crappy PSUs and hence can't supply the required current.

Impedence and sensitivity (the db figure the OP refered to) together give an indication of how "hard" a speaker is to drive. A speaker with a low impendence (say, 1 ohm) and low sensitivity (~80 db) would be an absolute ***** to drive. For an example of this type of speaker, look no further than the Apogee Scintilla (RIP)...

With respect..........first of all, I said GENERALLY. Secondly, the better speaker manufacturers and more expensive speakers CAN handle a lower Ohm load than less expensive speakers. You really won't find many "cheap" or "crappy" 4 Ohm speakers. Therefore, GENERALLY, the lower the Ohm rating on a speaker the higher quality the speaker is. Also, GENERALLY, to find an amp that can push a 4 Ohm speaker you will have to buy a bigger amplifier, which means bigger components which GENERALLY means higher quality.

OF COURSE this is not always true and there are great 8 Ohm speakers out there but they will GENERALLY not measure up to a 4 Ohm speaker in quality of build and sound quality. GENERALLY.

[reider]

Originally Posted by Pilam69

With respect..........first of all, I said GENERALLY. Secondly, the better speaker manufacturers and more expensive speakers CAN handle a lower Ohm load than less expensive speakers. You really won't find many "cheap" or "crappy" 4 Ohm speakers. Therefore, GENERALLY, the lower the Ohm rating on a speaker the higher quality the speaker is. Also, GENERALLY, to find an amp that can push a 4 Ohm speaker you will have to buy a bigger amplifier, which means bigger components which GENERALLY means higher quality.

OF COURSE this is not always true and there are great 8 Ohm speakers out there but they will GENERALLY not measure up to a 4 Ohm speaker in quality of build and sound quality. GENERALLY.

With respect.... I have to agree with richteer's rebuttal of you post, and to add that you GENERALLY don't understand what are you talking about. Sorry.

[NJMetsFan]

Originally Posted by Pilam69

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.

Lower ohm rating doesn't mean better. The less the resistance is, the more crap that will go to your speakers. Take this example.

You have an amp that does 400w @ 4 ohms but you can bridge it to give you 800w @ 2 ohms. Your power is increased but your signal quality will go down. If that same amp can handle a 1 ohm load, it will give you even more power but that power is dirty. Which mean that your sound quality will go down. It might be very loud, but it won't have the same sound quality.

I would take a 800w @ 4 ohm amp over a 800w@ 2 ohm amp, because your sound will be better. It will cost a lot more to buy a amp that puts out a lot of power at 4 ohms than one that puts out the same power at 2 ohms.

[NJMetsFan]

http://www.surrealmirage.com/subaru/tip.html#thd

I just found this site...and I quouted some info.

THD - Total Harmonic Distortion is a good number to help determining a good amplifier from the cheapos. For starters, a THD of 0.1% or greater is audible to the human ear, anything less you won't notice. Head units usually have a very low THD. THD usually comes into play in amplifiers, especially when running at a lower ohm rating.

Power Ratings at Different Ohm Loads - An Ohm is a measurement of resistance in wiring. Every type of wire has resistance, if you have no resistance you have a short, and lots of sparks. Manipulating Ohm loads with speakers and amplifiers can be very beneficial. When you decrease the ohm load by half, you will increase power by a factor of two. Lets say you have an amplifier that puts out 50 watts/channel at a 4 W load. If you have a 4 W speaker, you get 50 watts. If you have a 2 W speaker you will get 100 watts, but there is one caution. When you decrease ohms, you increase THD.

[saprano]

Originally Posted by NJMetsFan

http://www.surrealmirage.com/subaru/tip.html#thd

I just found this site...and I quouted some info.

some more learning, everything is starting to make sense now.

[NJMetsFan]

Originally Posted by saprano

some more learning, everything is starting to make sense now.

Glad to help.

[d_rob1031]

Originally Posted by NJMetsFan

http://www.surrealmirage.com/subaru/tip.html#thd

I just found this site...and I quouted some info.

I'm really glad someone brought THD up. To me, it is the most important rating on any amp.

Example: If you have 1000watts @ 10% THD, which is what most HTIB run at, you lose a lot of that 1000watts (which is peak, mind you, something else I'll touch on) that is used up by the amp.

Take that same 1000watts @ < 0.05% THD, which is what a lot of amps run at, better ones run even lower, you're going to break every window in the house. Which is why they don't run at 1000 watts

I just looked up the Onkyo 805 and it runs at 130watts per channel at 0.05% THD. If you took that same 130watts per channel at 10% THD you would have horrendous sound with crackling and loss.

The HTIB also are rated at peak power whereas real receivers are rated at RMS (root meat square). RMS is the wattage at which it's able to consistently do over a stated period of time. Peak power is the max it will do before it blows its self up, in other words, it never makes its peak power.

Hope this clears up why HTIB's usually suck (there are decent ones out there) and explains THD and how it's used.