Help Choosing Amp

[Sam Kapasi]

Each woofer inside is 300Wrms/ 1200W peak.

It will need a real strong amplifier. Also more power will be required as it is a bandpass box and the woofers are completely sealed inside.

[blueraven316]

Originally Posted by anToNIcHeN

whereas, in the other case, if you carefully adjust the gains.... you are safe..... like hydrashok has said.. only upper 2/3rd.... that if you have 600 RMS sub, you can safely attach 1000 RMS amp to it..

regards,
ant.

I have to disagree to this, if you run a 600 RMS pair of subs with a 1000 RMS amp and adjust the gain so low to that it comes down to approx 600, then why buy a 1000 RMS amp in the first place ? its a waste of money.

On the upper 2/3rds gain of a CEA rated 1000 RMS amp the amp will still chrun out close to 1000 RMS which is a whopping much higher than 600 RMS. It is dangerous, period,

If one uses a 800 RMS amp with a 600 RMS pair, then one can play with the gain, but using a 1000 RMS amp and then underpowering it is no good.

[blueraven316]

Originally Posted by Sam Kapasi

Each woofer inside is 300Wrms/ 1200W peak.

It will need a real strong amplifier. Also more power will be required as it is a bandpass box and the woofers are completely sealed inside.

Yeah Sealed and Bandpass enclosures need powerful amps to get the right potential of the subs to come out.

But that need not be double the power, even 20 % more than subs is fine.

[Sam Kapasi]

No blueraven baba, you aren't entirely right here. Navin will be along shortly to technically explain why, especially in the case of subwoofers, more power is better.

I do hope he will be well enough to post that. Come on old chap, explain to to the young one why.

[redeye]

sam i asked john about the recent thread "bad experience with sprocket" he told the lancer had local wiring so he advised to change him for better ones and there was distortion because the pioneer speakers were wore out ...told john about team-bhp he said he's gonna join very soon..

[redeye]

i bought this beast for 25k on 5th sept ..did'nt enough money to buy a powerful amp then, i bought it in sprocket ..john told me i'm the first to buy in bangalore ..i'm not sure i'm the first in india... but i would be really happy if i am the first...

[hydrashok]

Don't sealed sub set-ups need double the amp power vis-a-vis ported set-ups to achieve the same output?

In a ported box, the air pressure/rear wave of the sub's excursion gets to exit through the port. So the sub's cone can move in and out quite a bit, and generate more sound output, as well as pressure. And since the resistance to movement (of the cone) is not much, the power required from its amp is not so much.

But in a sealed box, the air pressure created by the rear wave remains inside the (airtight) box. So the sub's cone cannot move backward much. It cannot move forward a lot either (as compared to a ported set-up) as the vacuum built up by sealed rear area limits its forward excursion. This way the beats (outward & inward movements) are quick & tight. And this resistance (to a lot of outward & inward movement) requires that a lot more power (ideally double the power) be fed to the sub if the output is to be more-or-less equivalent to the output the (same) sub can produce in a ported set-up.

Now have I talked myself stupid here? Huh? Huh?

And doesn't the same principle apply to a bandpass sub? After all, a bandpass box is mostly like a sealed box in a ported box (or a sealed box joined to a ported box), right? Gurus, could you correct me if I'm wrong?

[navin]

I guess Sam really wants me to mouth words like "The Mechanics of a woofer (sub or not) is best explained by studying mass-spring dynamics."

There are actually 12 components that make up the loudspeaker. They are the Basket, Top plate, Back plate, Pole piece, Magnet, Cone, Voice coil, Spider, Dustcap, Gasket, Leadwire and Terminal. When you look at a loudspeaker from the front you see the cone and dustcap, and it looks like a speaker. If you look at the loudspeaker from the side you will see the bottom of the cone has two wires coming out that run to the terminals. These two wires are the two ends of a single wire called the voice coil. If you look a little closer, you will see the cone is attached to another corrugated piece at the neck or bottom. This is called a Spider. there is a cutaway pic here.
http://electronics.howstuffworks.com/speaker6.htm

about 2/3rd of the way down on this link below is a electrical circuit that is analgous to the mechincal components of a loudspeaker. I find this the easiest way to visualise how a loudpspeaker functions.
http://en.wikibooks.org/wiki/Acousti...ic_Loudspeaker

The Spring effect is created by the Sealed Box behind the Loudspeaker. The less Lossy the box the sitffer the sping and the more the energyry will be required to counter the spring effect. Similarly the heaviver the mass of the cone the more the energy required to move it. Hence Heavy woofers in small sealed boxes require the most energy to move. Energy is what the amplifier provides (measued in Watts). A simple way to understand this is here
http://www.trueaudio.com/st_trade.htm and this site is an excellent resource for DIYers. (shamless plug: if you look at the Dave Platt link you will find one of my earlier crossover circuits under "go here for further information").

For the more technically inclined this PDF covers the basics well.
http://www.iet.ntnu.no/courses/ttt41...ng_answers.pdf and YES! microphones and to some extent record player styluii work almost the same way!

[navin]

Originally Posted by hydrashok

or a sealed box joined to a ported box...

This is a 4th order bandpass. A 6th order bandpass is ported - ported.

I can see some of you logging oout and others crying "U-N-C-L-E". :-) Sorry if I digressed.

[Bass&Trouble]

Originally Posted by navin

There are actually 12 components that make up the loudspeaker. They are the Basket, Top plate, Back plate, Pole piece, Magnet, Cone, Voice coil, Spider, Dustcap, Gasket, Leadwire and Terminal. When you look at a loudspeaker from the front you see the cone and dustcap, and it looks like a speaker.

"U-N-C-L-E"... you forgot the poor surround! Or maybe when you say cone, you mean cone-surround assembly.

Also, worthy of being named separately would be the former.

[navin]

Thanks B&T former and surround so that makes it 14 components. The physics still remain the same.

[blueraven316]

I still believe more power is ok but not double the power for a speaker in our cars, especially the stuff that sells in our markets are very entry level stuff and connecting a 600 RMS amp to a 300 RMS voice coil sub is dangerous and pushing it's luck no matter what enclosure is used.

B&T ? Navin ? Autophile ? Someone reply

[prince85]

Originally Posted by blueraven316

I still believe more power is ok but not double the power for a speaker in our cars, especially the stuff that sells in our markets are very entry level stuff and connecting a 600 RMS amp to a 300 RMS voice coil sub is dangerous and pushing it's luck no matter what enclosure is used.

B&T ? Navin ? Autophile ? Someone reply

Are you by any chance referring to JBL Subs/Amps as entry level stuff???? coz we are discussing JBL equipment in this thread

[Sam Kapasi]

lol no prince, you can lower those eyebrows hehehehe

Blueraven means to say that in India we sell more entry level equipment from higher end brands. Not to be confused with Sony et al. That is dysentery level stuff.

No, for example in the USA JBL sells mostly the GTi series, $1000 subwoofers and $5000 amplifiers.

[redeye]

so guys if i choose the gto1201.1 amp would it be too much power .. i'm confused which one is the best for my sub woofer ... to perform at it's best..