JW

I have a pair of 100watt 3 way sony speakers and a 125watt 12inch kicker subi.

Would this be a good amp? http://www.strathfield.com/ViewProduct.asp?ProdID=320


How loud should a 125watt 12inch sub be cos at the mo on a 150watt bridged amp its not loud at all?
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Tim Team Reaper.

They make subs lower then 500w Mate of mine picked up a 12inch Pioneer 600w sub for around $180 for his Hyundai Excel. He's looking at running it through a Clarion 450w Amp. not sure how it will go, but the sound system guys said it will work. So maybe your ebay unit will work fine.

Failing that, ask Brett
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https://www.halfdonethings.com/

90% of Car-Audio ratings are wank..

Sorry to be grouchy, but they are.. Its an scene where neon-lit perspex covers and carefully aligned super-oxygen-free-directional-double-overhead-insulation-electron-conductor-matrix's (wire in other words) are more important than anyone actually understanding the difference between RMS and PMPO power ratings.

a *real* 500 RMS watts of audio power would be pain-producing levels inside a car..

In my car, I have 3x 200 watt Response amplifiers (600 Watts RMS Total) driving 2x 12" drivers, 2x 6x9" mid-high's and 2x 6.5" mid-high + tweeters, and the amps are set to about 2/3rds of full power. (yes, there is no back seat). as anyone who has heard it can tell you, even at 2/3rd power its enough to make you want to get out of the car *now*.

If you want to get the best value-for-money with no-bull amps and speakers, believe it or not, Jaycars "Response" range is the most realistically-rated and low-wank-factor gear I know of. Seriously worth a look..

Most of the stuff from Strathfield and JB is aimed more at the rice-burner crowd where show is more important than go.. I mean, Head-Units with "screen-savers".. c'mon guys.. we all drive along watching the pretty patterns on our car-stereo's now dont we ?

Jaycar used to have a thin green book called "UIltimate Car Audio" (or something like that) that had the best low-down on car audio that I've seen. If you can find a copy, its well worth a read.. Real Info without the shiny glitter..

As far as your question on "how loud should it be ?" goes. Well, -> This <- loud..

If you're talking real RMS watts, then 150 should be plenty loud enough.. if you mean "150 watts total Max Power" then it could mean anything from 10-50 of real watts, which mightnt be very loud.

Also the "sensitivity" (efficiency) of your speakers makes a *big* difference in how well those watts get turned into sound pressure levels. pushing lots of watts into a low sensitivity speaker wont produce as much volume as less watts into a higher sensitivity speaker.

Then of course you head over into sound-*quality* land and start to talk about bandwidth, linearity, cross-over freqencies and lots of other juicy stuff that usually gets ignored by those to who having "1.21 Gigawatts" is more important than being able to distinguish a hi-hat from a pair of maraccas.

If you're talking to a car-audio salesman and they cant tell you the continuous RMS watts per channel for your gear, head the other way fast..
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Great minds discuss ideas. Average minds discuss events. Small minds discuss people

The ratings i put up are the rms rating and yes what the hell is this peak power shit like i mean why put it on there when its the rms that counts.

Id like to know is the brand name BOSS any good? they have a 1000peak power sub (rms not sure) for $60 i know the rms will be much lower but what id like to know is are they a good sub or are they crap as in they distort or die or whatever?

Only reson im looking at them is cos of the price not cos they are 1000watt peak its only cos they are the cheapest sub iv found so far that eaven at rms rating should be loud enoughf.
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Tim Team Reaper.

Well basically PMPO is a marketing terms, and it means nothing. So you can't really convert between it and RMS. However as a general rule of thumb you can guestimate that the RMS will be 10x less than PMPO

The next thing is THD. More than likely that rating is at 10%THD which is to high for good audio. In your car I'd be looking for about 1%.

My knowledge in this area is starting to run thin...and it's really a whole art to itself.

I think you can reduce THD by not turning up the speaker as much...so if you ran at say 75% of the full output it should sound fine.

I have two of the Jaycar Re/Sponse 15" double magnet 300WRMS subs, and some other 12" speakers (in the house, not car!) running off a 750WRMS per channel amp, and I think if I put that in a car it'd literally blow the windows out! It's easily as loud as a rock concert in the house (measured 110db continuously )

I used to run two 12" subs ($30 each 70% off specials from Strathfield) in large boxes from a 2x65WRMS AWA power amp in a previous car, and people could feel the bass from 20m away, but it wasn't insanely loud in the car.

Keep in mind that if you had an amp delivering a real 600WRMS continuously it'd be drawing well over 50A from the car battery!
That doesn't add up too well when you have to run the rest of the car as well from what is probably a 48A alternator


A while back I read some info on PMPO power ratings, and they basically have no relevance whatsoever. They've changed from being an instantaneous peak output power at massive distortion levels, to a theoretical peak output power of the amp's power supply into a dead short - with no actual amp stage involved!!

Car audio ratings used to be simple, where they used "peak" or "music" power, which was generally double the RMS value, and fairly standard accross brands. Once mini "hifi" systems got on the PMPO bandwagon (wow a micro system with 2 megawatts!!!) the car stuff followed, and we have the ridiculous situation you see today...

Originally peak power measurements did have some relevance, because music is generally comprised of peaks, and the way the speakers handle those peaks plays a big part in how they end up sounding.
RMS ratings are usually a continuous maximum power handling of a 1kHz sine wave which, let's face it, doesn't cover much musical content
Generally though, a speaker with a higher RMS rating will handle higher peaks, and be a more powerful speaker in all conditions.
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The Engine Whisperer - fixer of things

Last edited by DumHed on Thu Jun 23, 2005 9:25 pm; edited 1 time in total

Question


Would 2x 125 watt 12inch subs have more bass then one 12inch 250watt sub?

Allso i have a set of 3ways for the back so what should i get for the front? some 2ways or some tweaters or what?
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Tim Team Reaper.

2 x 12" subs will give more cone surface area than one 15" sub, there will be 3db more sensitivity due to there being two speakers, and you may be able to bridge the amp to run them in parallel for more power if it can handle it.
12" speakers also tend to give a "punchier" sound than 15s due to less moving mass, so they respond quicker to musical transients.

One thing to keep in mind though is that if you run the speakers in parallel and the amp in bridge mode you'll lose some of the punchiness due to reduced damping factor (which is the amp's ability to control the cone movement accurately).
Personally I like to run the speakers from individual amp channels, and sometimes even run 8ohm speakers instead of 4ohm, which gives a better damping factor and a "tighter" sound.

You could even run two 12" subs in series, and get about the same output power as one 15" sub, but with a cleaner, punchier sound and more dynamic headroom before distortion.

Just out of interest, two 10" subs gives almost the exact same cone area as one 15" sub
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The Engine Whisperer - fixer of things

Last edited by DumHed on Thu Jun 23, 2005 9:31 pm; edited 1 time in total

so better quality base and slightly more loudness and less boot space?
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Tim Team Reaper.

you should get better sound in general, and you can get away with smaller boxes so the boot space should be similar.

You could even do an Isobarik speaker box (Jaycar has a design) with two speakers in it for extra bass response from a smaller box size. It basically gives the effect of one speaker with a much higher damping factor and power.
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The Engine Whisperer - fixer of things

so an isobarik box is one box that holds the two subs?


Hmm insted of buying a louder sub maby ill get another one the same as what i allready have and run em in paralel.

Eaven tho the louder sub is $30 cheaper and is sony and the one i have is kicker.
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Tim Team Reaper.

an isobarik enclosure puts the two speakers on top of each other, running in push pull configuration, so they actually work as one speaker with two coils.
It's a good way to get heaps of bass out of a very small box, but isn't as efficient as two separate speakers, and is harder to design / construct.

The most important thing with most speakers is to have the right sized box.
One nice thing about buying any of the Jaycar speakers is that they give you optimum box sizes and designs so you don't have to do too much work, or take wild guesses.

Most of the car subs you get from anywhere else have no real specs so you have to guess, or use one of the off the shelf boxes which are not really matched to the woofer at all.
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The Engine Whisperer - fixer of things

Which would you reckomend?

2x125watt kickers 12inch or one 250watt 12inch sony?


Im tippen the sony would be better.
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Tim Team Reaper.

quite likely, but sony car stuff can be pretty variable in quality.

I know someone who had a single Re/Sponse 12" double magnet sub (250WRMS), in the recommended box, and it rattled the mirrors of cars next to him at traffic lights
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The Engine Whisperer - fixer of things

quote:

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Originally posted by DumHed:

Just out of interest, two 10" subs gives almost the exact same cone area as one 15" sub

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