How to properly drive a sub? Subamp power?

[JojoD818]

Hi,

I used several amps to drive a sub in a temporary ported box. I feel the sound is weak, one of my 100W ss amp clips but I like the sound before it clips, gainclones (OPA549) sounds also weak. The sub is 12" 300W, how much power must the power amp be capable of to fully drive the sub without clipping.

Any ideas?

JojoD

[SkinnyBoy]

depends on the encolsure.... I've bottomed out a 10inch, 250watt rms sub in a small sealed box using 150watts..... so.... depends on the enclosure really..

[sreten]

Simply put :

There is a region of the subwoofer, where maximum output
is determined by excursion limits. At the lowest frequencies
power can be very modest but it rises rapidly with frequency.

At higher frequencies output is power limited by the amplifier.

High SPL's in the bass are not easy to achieve.
Often thesimplest way of achieving +6dB SPL's
is to build another identical subwoofer.

sreten.

[priscared]

"depends on the encolsure.... I've bottomed out a 10inch, 250watt rms sub in a small sealed box using 150watts..... so.... depends on the enclosure really.."
howd ya feel
anyone know anything about a 2n3055, anyone want some?
Daniel

[SkinnyBoy]

Originally posted by priscared
"depends on the encolsure.... I've bottomed out a 10inch, 250watt rms sub in a small sealed box using 150watts..... so.... depends on the enclosure really.."
howd ya feel
anyone know anything about a 2n3055, anyone want some?
Daniel

I'm a dumbarse, and you haven't even worked out how to use the quoting system yet? lol

and it wasn't actually me who did it... or my sub.. lol so THERE!

[JojoD818]

OK I am now confused . Low frequency needs less power to achieve? Or is it the other way around? I am only interested in frequencies below 100Hz, so does it really need to be high powered?

Which one is easiest to drive for an amp?

1. Sealed
2. Ported
3. Bandpass (4th order only)

Please clarify, thanks!

JojoD

[SkinnyBoy]

Originally posted by JojoD818
OK I am now confused . Low frequency needs less power to achieve? Or is it the other way around? I am only interested in frequencies below 100Hz, so does it really need to be high powered?

Which one is easiest to drive for an amp?

1. Sealed
2. Ported
3. Bandpass (4th order only)

Please clarify, thanks!

JojoD

*shrugs* 300watts rms sub... I wouldn't bother with anything more than 200watts... but if you feel the need, 300watts might be better...... but I don't know the sub, or the box, or anything.. so.. yeah....

[JojoD818]

Originally posted by SkinnyBoy



*shrugs* 300watts rms sub... I wouldn't bother with anything more than 200watts... but if you feel the need, 300watts might be better...... but I don't know the sub, or the box, or anything.. so.. yeah....

It's a cheap sub I bought for an experiment. It doesn't have any brand markings but says 300W @ 4 Ohms and is 12" in diameter.

I built a 2 cu. ft. sealed box for testing purposes and tried a gainclone to power it. At low settings, it sounds great but at high settings, it distorts. Must be the gc protection kicking in?

The I used a 100W solid state amp, it plays a lot louder but at high settings, the amp clips (protection kicks in).

So, back to the question... do I really need a huge amp for a sub?

[SkinnyBoy]

Originally posted by JojoD818



It's a cheap sub I bought for an experiment. It doesn't have any brand markings but says 300W @ 4 Ohms and is 12" in diameter.

I built a 2 cu. ft. sealed box for testing purposes and tried a gainclone to power it. At low settings, it sounds great but at high settings, it distorts. Must be the gc protection kicking in?

The I used a 100W solid state amp, it plays a lot louder but at high settings, the amp clips (protection kicks in).

So, back to the question... do I really need a huge amp for a sub?

well.. in all honestly.. you SHOULDN"T need a big amp.... I mean.. if its a cheap sub, would you really wanna pay alot for an amp to run it?

[a31_ford]

Can I get my 2 cents in here

Two things are going to affect the "destruction point" of ANY speaker or dome.

CLIPPING and OVEREXCURSION !

ALL speakers will handle MORE power than they are rated for, But Only If It Is NOT CLIPPING!

HOWEVER, Overexcursion just ONCE, and it's FRIED!

Clipping is this, > DC Voltage in massive amounts for massive time periods < . It simply causes the voice coil to become a heating element (like the one on a electric hot plate) the bobin the voice coil is wound on, must be light weight as to be able to move with the speakers in/out movement, but strong enough to not fall apart while doing so, therefore the compromise is it can't take a lot of heat without melting (plastic) or deforming(composite), or burning (paper), it has no place to give the excess heat to (except the air gap between the magnet poles) so it burns or deforms, and causes the voice-coil wire to rub on the magnet structure, thus eventually breaking the wire or the flex lead.

so SOME speakers will take SOME clipping, (But NOT for long, or large amounts).

Overexcursion, IS the simple act of forcing the speaker's diaphram to knock it'self to death by hitting the basket that holds it inplace, or to push away from the basket with enough force to seperate the spider, and/or lead wires, and/or surround from the basket. the later being MUCH harder to do, but since it's on the "normal" side of a sound wave, yes it can be done.

(Side note: Properly wired speaker will cause a "+" voltage to move away from the basket, where as "-" will move toward... )

1000's might NOT belive this, but it DOES matter which way ALL the speakers in a group are wired (NOT phased, that is simply to make them all work in unison) . Here's an example, take BOTH sets of woofer wires, and reverse them (so both "+" are now the "-" etc. Belive this or not, these speakers will NOT last as long as an identical set, wired the other way, reason ?? The speakers when hit with a massive bass note will wack the frame (basket) and die sooner, than the other set! The other set will attempt excursion outwards, and the limits of the spider and surround will be reached and act as a shock-absorber, and pull the mass of the cone back into the basket.

Oh, someone is going to say "action=oposite reaction", ah... the original bass note was the action, and since some of that action is now taken away by the surround, there is less force to push the cone back into the basket, hence NO slaming into the frame.

Someone else is going to say " but sound waves move both + and - of "0" (actually No they do not, they move + and - of "Null" WE build amplifires that use "0" as null, and no matter what, any sound that is fed to the amp, will start with a "Plus" movement... (just like a cars's starter motor, it don't care which terminal is "+" it will turn the same direction every time, the same with an amp, "+" is the starting point for that waveform for any signal into the amp. Therefore, all notes from the speakers will start with the cone moving outwards when the speaker is wired correctly (watch it, as there are different meanings of "+" eg: most tweeters move the other direction when hooked up +, do a search in it)

(Double side note: medical instrmentation amplifiers are the only amplifiers made that can (if wanted) start a signal waveform on the "-" of things something to do with the human body being reverse of how we build electronic's in the first place.


NOW on to the final chapter in this (WHEW, I'm long winded ! ).

Anyhow, Bass notes and power amps, a great rule of thumb " half the frequency, double the power" most "thumpy" bass is somewhere areound the 160hz area (cheap getto-blasters empasize this region, and it's known as "synthetic bass"), (it's also the easyest bass to feel with our body's being a structure of 50% water or something like that, (look up sound propagation in water, you'll find out why this area is so good) onward, the notes below the 160hz area, next octive down is 80hz, next is 40hz, next is 20hz . (These would be "Root" to one harmonic down)

SO, if one is using 150 watts @ 160hz, in order to repoduce a 40hz note correctly, they would need 600 watts ! and at 20hz it would be 1200 watts!!! Most people that claim "MY system does 20hz when the amp is almost clipping"are blowing air from open holes in their body (note I say MOST) the power factors involved get quite huge and since most amp's only have 3db of headroom it' simply not capable of doing so! (however if someone is listening to 160hz note @ 1 watt and whats to hear an 80hz note, at the same volume, they only need 2 watts. )

Here's that rule of thumb again, "half the frequency, double the power"

And who said "I can make a sub sound great with 50 watts" at what SPL ? 80 ?? and over what frequency range > 160-300hz ??

MC Hammer should re-write his HIT..... "It's Getto time"...

Everybody have fun , cuz I know we all LOVE "real bass", don't we