View Full Version : MAX Output & RMS
Hi,
I'm thinking of improving the sound in my Leon a bit with some custom speakers and 6 x 9 (don't want sub) and some amps to drive it all.
I'm pretty much certain on what to buy but was wondering how to match up the amp power to the speaker's max input.
For instance, the speakers (for the doors) are 200W with a Rated input of 40W; 6 x 9 300W with Rated 80W. Which amps should I go for?
the AMPs I've seen which I could use for the doors can be either:
1) 4 x 80W, 4 x 40W(RMS)
2) 4 x 170W, 4 x 75(RMS)
One AMP seems to closely match in RMS terms and the other in Max Output terms. Which would be the best to pick. I'm after quality of sound if that helps.
The AMP for the 6 x 9 is 2 x 300W (2 x 150W RMS).
Hope it all makes sense.
Route mean Squared
square root of half the peak signal if my scholar days are right
so if the peak was 8, the RMS would be 2
Route (8/2)
Mark
Ok, the rated input must be different to RMS, e.g.,
200 / 2 sqrt = 10 and not 40 as said here for the 200W speakers
and
170 /2 sqrt = 9.(lots of digits) is not 75.
Wonder what they mean by rated input?
DIN 45500: at 4 ohm 4x 80 W
(14 V, THD 0.5 %) at 4 ohm 2x 200 W
DIN 45500: at 2 ohm 4x 100 W
DIN 45500: at 1 ohm -
Rated / THD: at 4 ohm 4x 75 W / 0.04%
(14.4 V, 20 Hz - 20 kHz) at 4 ohm 2x 200 W / 0.1%
Rated / THD: at 2 ohm 4x 100 W / 0.1%
Rated / THD: at 1 ohm -
Maximum (14.4 V): at 4 ohm 4x 170 W
Maximum (14.4 V): at 4 ohm 2x 400 W
Maximum (14.4 V): at 2 ohm 4x 200 W
These are the figures from the advert.
You can see what I'm getting at. 4 x 200W would be nice to drive those MAX INPUT 200W speakers. But would 4 x 100W Rated output be too much for the same speakers Rated input of 40W?
Does anybody know what it all means. Maybe I should email them?
:confused:
http://www.doctronics.co.uk/rms.htm - better description
I was rather drunk when I wrote that, but the above (I think) describes it the same.
M
Mark,
You going to be have to be drunk to understand that!!!
http://www.doctronics.co.uk/rms.htm - better description
I was rather drunk when I wrote that, but the above (I think) describes it the same.
Still don't answer me question though!
OK - I'll print it off & do some sums over lunch
M
I found a good link regarding speaker power ratings/amp power ratings selections hear:
http://www.mbquart.com/ma-techpapers.htm#blow
Blimey, it's been a few years since I was into this. I won't be much help, but what I remember is:
The ONLY figure you should be looking at is the RMS power. Manufacturers like to quote Peak Music Power Output (PMPO) to bump up the figures, but it's only for pub-talkers. RMS, nowt else.
Also look at the Total Harmonic Distortion (THD) figure, the lower the better. Again manufacturers will quote higher power ratings, but against a higher %tage THD.
"Rated / THD: at 4 ohm 4x 75 W / 0.04%". This is the one to look for, all the other figures give a higher THD, and therefore poorer sound quality.
Oh, and look at the 4ohm power output only. 2ohm is quoted if you bridge your speakers (usually a pair of subs), but some amps don't like to run into 2ohms.
Feel free to correct me if I'm wrong, as I said, it's been a while since I was into ICE (aahh, happy days) :rolleyes:
Gaff
GAFF There's more to it though.
The rated amp output also depends. Some amps rate there RMS at 12V and others at 13.8V. An amp that rated at 25W RMS @12V will put out in the neighborhood of 50W RMS @13.8.
prc - you're forgetting that the Amp drives the Sub?
it just means that you're not getting as much out of the sub as possible.
M
That's true Mark.
I'm still wondering wheather amping via the speaker level input is a worth while option. I am also looking to upgrade the sound of my toledo. Debating between upgrading the speakers (using stock receiver power) + Infinity Basslink or upgrading speakers with external amp getting and adding the sub/amp latter on this year.?
MarkP, prc and Getgaff,
Thanks for the replys guys, you've been most helpful. I know exactly now what to buy.
By the way prc, I'm running my setup through a different head unit. Think this is a lot better than using the speaker inputs.