bass boost

[lebomb 10+ year member]

Used to have my bass boost on all the time set to about +6 on my amp. I readjusted my gains and turned the bass boost off.......sounds TONS better.

Never, ever use bass boost, it only boosts certain frequencies.......usually around 50Hz or so.

 

[DBfan187 5,000+ posts]

clipping won't hurt your speaker if they can handle the amount of power it will cause.

 

[psych0ticnemes1 5,000+ posts]

clipping won't hurt your speaker if they can handle the amount of power it will cause.

it could fry a coil thermally without overpowering the sub

 

[DBfan187 5,000+ posts]

it could fry a coil thermally without overpowering the sub

That's overpowering it.//content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

Only 2 ways to damage a speaker, exceed it's thermal limits, and exceed it's mechanical limits. I guess a 3rd way would be physical damage.//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[audioholic 5,000+ posts]

A squared wave does more than simply boost wattage output, it also diminishes cone motion. A sub uses its cone motion to pump air in and out of it, thereby cooling itself. Soooo, what's gonna happen when you boost wattage through the sub while simultaeously hurting its natural ability to cool itself? Not hard to figure out.

1,000 watts squared versus 1,000 clean watts are not the same to a speaker.

 

[DBfan187 5,000+ posts]

Uhhhhhhhh NO!

http://www.audiogroupforum.com/csforum/showthread.php?t=4332&highlight=clipping

 

[audioholic 5,000+ posts]

Uhhhhhhhh NO!
http://www.audiogroupforum.com/csforum/showthread.php?t=4332&highlight=clipping

That thread explains that the situation is frequency dependant, so?

 

[DBfan187 5,000+ posts]

2nd post

Same thing. Power -causes- cone movement. The clipped wave doesn't cause the coil to remain still at the peaks because the speaker works as an electrical and mechanical low-pass filter and the sudden stopping to stay still is a high frequency phenomenon. If you low-pass the clipped output the "edges" and "flat tops" of the signal disappear. The high frequency output of the amplifier doesn't cause much power dissipation in large woofers as their impedance is higher at those frequencies.

What it's saying is clipping = high frequency information.

Also the thread states that clipping WILL NOT HURT YOUR SPEAKERS!

Too much power is the ONLY thing that will destroy a well built speaker. Too high a peak power can cause it to move too far, and cause mechanical failure. Too much RMS power for too long will cause thermal failure.
A clipped signal will not damage any speaker, if it is at a level low enough so that the heat can be dissipated, and it doesn't move far enough to mechanically damage it.

Take a square wave source signal from any number of test CDs, and play it through your system at a low volume. If you have a power supply on the system, you can play that 100% clipped signal indefinitely, and the system will never miss a beat.

As Rob said, a square wave is not made up of positive and negative DC components. The true makeup of a square wave is the fundamental frequency signal, combined with all of the harmonics of that fundamental.The combination of the many different, but related, sine waves results in a square wave.

You can prove this for yourself by running a low frequency square wave signal into a variable crossover, and look at the output on an oscilloscope. with the crossover bypassed, the square wave will be perfect. But, engage the low pass filter, and begin bringing it down towards the fundamental frequency, and the wave shape begins to look like a slightly clipped sine wave. If you turn the crossover point all the way down to the fundamental frequency, the scope will display a perfect sine wave.

Just something for those with nothing better to do this weekend...

The only thing that thermally damages speakers is power... more specifically: average power over time.
I'll explain...

If you take a given amplifier, let's say 100 watts and operate it just below clipping with music material, the "Crest Factor" of the amplifier's output is equivalent to the "Crest Factor" of the program material.

"Crest Factor" is the difference between the average level of the signal and its peak level. For example, a pure sine wave has a "crest factor" of 3dB, meaning that it's peak level is 3dB higher than its average level. We all know that 3dB represents a power factor of 2, so another way to look at it is that the peak power of the signal is twice that of its average level. So, if we play a sine wave on our 100 watt amplifier, just below its clipping level, the average power (over time) the speaker is needing to dissipate is 50 watts.

A true square wave, by comparison, has a crest factor of 0db, so it has equal average and peak power. Our 100 watt amplifier, playing a square wave, unclipped, into our speaker requires that the speaker dissipates 100 watts of power (twice the heat as a sine wave).

Music has a significantly higher crest factor than sine waves or square waves. A highly dynamic recording (Sheffield Lab, Chesky, etc.) typically has a crest factor of 20dB or more, meaning that its average power is 100 times lower than its peak power. So, if we play our 100 watt amplifier just below clipping with the typical audiophile recording our speaker is only needing to dissipate 1 watt of average power over time.

Modern commercial recordings typically exhibit crest factors of around 10dB, meaning that the average power is 10 times lower than the peak power. So, our 100 watt amp just below clipping would deliver an average power over time of 10 watts that the speaker has to dissipate.

Okay, so what happens when we clip the amplifier (which we all do at times). When the amplifier enters into clipping, the peak power no longer increases, but here's the KEY... THE AVERAGE POWER CONTINUES TO INCREASE. We can often tolerate a fair amount of clipping... as much as 10 dB or more above clipping with a reasonably dynamic recording... a bit less with a compressed commercial recording.

So, if we turn the volume up 10dB higher than the clipping level with our Sheffield Lab recording, we have now reduced the crest factor of the signal reaching the speakers by 10dB... so instead of needing to dissipate 1 watt average, we are asking the speaker to dissipate 10 watts average, and we're probably ok.

If we turn up the volume 6dB past clipping on a compressed commercial recording (or bass music recording), we have taken the crest factor of the signal from a starting point of 10dB to only 4dB, asking the speaker to dissipate an average power of 40 watts instead of 10 watts... that's FOUR TIMES the average power, which generates four times the heat.

SO, in most cases, the reason clipping can damage a speaker really has nothing to do with anything other than an increase in average power over time. It's really not the shape of the wave or distortion... it's simply more power over time.

When someone plays Bass Mekanik clean (unclipped) on a 1000 watt amplifier the average power is 100 watts (10dB crest factor). You can also make 100 watts average with Bass Mekanik by heavily clipping a 200 watt amplifier.

If someone is blowing a woofer with 200 watts of power due to a lack of restraint with the volume control... they will blow it even faster with a 1000 watt amplifier because they will probably turn it up even more and now they have more power to play with... this is the recipe for aroma of voice coil.

When woofers are rated for power, an unclipped signal is assumed. We use test signal with a crest factor of 6dB for power testing and can run a speaker at its rated power for hours and hours on end without thermal or mechanical failure. For example, a W1v2 can dissipate 150 watts average power for eight hours or more with signal peaks of 600 watts. So, we rate the speaker for 150W continuous power. This way, when a customer needs to choose an amp for it, they will hopefully choose one that can make about 150 W clean power... Even if they clip the bejeezus out of that amplifier, it is unlikely that the speaker will fail thermally. This is a conservative method, but it needs to account for the high cabin temperatures in a car (think Arizona in the summer) which significantly impacts heat dissipation in the speaker. A top plate that starts at 150 degrees F is not as effective at removing heat as one that starts at 72 degrees F in the lab... and this affects the ramp up of heat in the coil.

DISCLAIMER: The frequency components of clipping can affect tweeters due to their low inductance and lack of low-pass filtering. Clipping essentially raises the average power of high frequencies to a point that can damage tweeters... Woofers and midranges couldn't care less about these high frequency components because their filtering and/or inherent inductance knocks that stuff out of the picture.

Best regards,

Manville Smith

JL Audio, Inc.

A clipped signal carries more average power than a non-clipped signal... this is the only aspect of it that affects a speaker thermally.
It doesn't matter if the signal is clipped before the amp at the preamp level or after the amp.

A sine wave can damage a speaker in a matter of seconds given enough power and in a matter of minutes at fairly moderate output... it depends on the impedance of the speaker at that particular frequency... if the impedance happens to be low, it might go up in smoke in a couple of minutes.

 

[Towncar 10+ year member]

Using the bass boost isnt bad in all situations. For instance the phoenix gold xenon 12s are absolute low end mosters, so they lack 40 hertz, and above tremendously. A slight bass boost helped the xenon out to fill in the region it could not play. For most people though, its no good to use in setups.

 

[stishdr 10+ year member]

i think i'll just stay w/out it, thanks guys..

 

[g0t-milk 10+ year member]

if your going to use your bass boost, set it where you *think* you might want it. ok? mine goes from 0 to 18. i set it at around 6, then set my gains. and it sounds incredible. external bass boosts are different and more dangerous. dont get confused tho, because they have external bass boosts, and external bass level controls (subwoofer volume control, not a bass boost). if your going to use bass boost, keep it nominal. at around 6db. thats all you need, if you need it at all. i know it gets louder the higher it is, but that distorts your bass, causes clipping, and plain sounds like shit. so if your going to use it, do it correctly. 6db is all you need depending on your sub and amp setup. im running 400watts RMS on my 2 comps, so all i needed was a 6db boost just to get a LITTLE more kick.

 

[Dmillz224 10+ year member]

i think i'll just stay w/out it, thanks guys..

sounds good. HU bass boost=blown subs

if your amp is good you dont need it