Super Subs

ridr4lif · Post by **ridr4lif** » Mon Mar 07, 2005 3:57 pm

WOW Kiki...it took me about 8 minutes to read all of that. I guess being an electrical engineer could come in handy being into car audio and whatnot. Keep up the good work

TEDD

Ryan from Ohio · Post by **Ryan from Ohio** » Mon Mar 07, 2005 4:39 pm

Once again Kiki puts the truth down.

Now maybe we all can move onto more constructive topics :)

spkrman · Post by **spkrman** » Mon Mar 07, 2005 9:12 pm

KikiTheCat wrote:ok, in order here..
SPL events being pointless (to ME mind you) because I'm a purist. I want an audio system for the music, and detail. The realism of it. That's why I compete pro circuot for SQ and not SPL. If I wanted to go deaf, I'd just run a jackhammer in the car and get the same effect. "Who's car is louder" to me is half a step away from the annoying punks like to crank their systems at stoplights to piss off everybody around them. It's done to try to impress others. Not for personal enjoyment.

With that attitude... whats the point of NASCAR? Whats the point of racing period? Why bother, who's going to get to 120mph in only 1/4 mile anyway??? whats the point of going in circles over and over and over... why bother?

SPL competition is 100% unrelated to bumping around town... hell... 90% of the top competitors can't even play music!

Its about getting together with friends to have a good time, meet new people, and to learn more about car audio period. AND TO HAVE A GOOD TIME! If you don't see a point in that... its time to check your pulse :)

But, you can have fun at 90db if thats what turns you on ]
this is where system design and tuning come into play. Personally, I like to use a pre-amp in my systems to avoid exactly what you described. By setting the pre-amp as your main volume control, you can attenuate the peak output with the source unit's volume and pre-amp level control so turning the stereo up all the way on the pre-amp master volume results in driving the system to the verge of clipping without going over the line. That's how I keep from destroying speakers myself. Not everyone wants to bother with setting up a system that way, but it is effective. Especially if you're after maximum SQ, and you're going to use noisegates or patametric or 1/3 octave EQing to shape the response for an RTA.
[/quote]

If you'd like to come set that up and pay for it... your more than welcome

Its a bud of mine, and I did the install for free - if he were running a more durable sub there would be no issues.

well, keep in mind that a speaker with a 4 ohm nominal impedance can drop to a quarter of an Ohm instantly when it hit's Fs. That, coupled with a quality amplifier having a power supply that can produce a minimum of three times the rated output of the amplifier, means that for an instant of peak demand, a "1200 watt RMS" amplifier can put out at least three times it's RMS rated peak power. That's part of why amps have such massive electrolytic capacitors in their power supplies. If the charging system isn't up to that peak demand though, then you're going to see the amplifier clip, and that sends DC voltage to the speaker when the AC output turns into a square wave output as the voltage rails sag. The problem with this, is that DC voltage across a speaker causes non-linearity and loss of motor control, as well as turning the voice coil into a heating element, which in turn can very quickly melt your coils and turn your speaker into a big paper weight.

This is a ~1 ohm DCR setup (dual 2 coils)... and please please tell me how a coil will fall below DCR in operation? Particularly when its heated!

I measured 2.2 ohms @ 46 hz (the speakers peak in its enclosure) and the amp was putting out 680 watts. There is no way the impedence fell below 1 ohm EVER in operation, unless something happened while the coil was burning up.

ok, I have two issues with this. Firstly, remember that not everybody wants the same things from an audio system, so a 10mm excursion may be plenty if the person has a small hatchback, and wants something to even out a factory system for low end fill, or they have little kids and don't want to deafen them.. Some people like a flat response.. not =12dB @ 40Hz for everything.. for those folks, entry level subs are plenty, and they can run a Comp12 from a 100 watt amp, which means no need for a big alternator, massive wiring,etc.

If you just want to hear some lower frequencies, you'd be better off upgrading your main speakers... no point in getting a 12" sub and an amp if you only need 100db of music.

10mm sub with 100 watts in a sealed box... is gonna be pitiful. But you are right, if thats all the person wants.. it'll work... but typically subs with that puny xmax aren't built very solid... and will give next to no low end.

Lastly I'd like to address the misconception of "power handling" ratings for speakers (yet again.)
The RMS and Peak power handling ratings on a speaker are thermal ratings. They are a measurement of how much heat (measured in watts) that the speaker coils can handle without melting. The better teh cooling design for the motor, and the heavier the coil wire etc, the more power the speaker can handle.
Now this does not mean that a "2000wRMS" speaker needs 2000 watts of power to reach peak output. Most times a subwoofer only needs around 80% of it's RMS rated power, if even that much, to reach full excursion in a proper enclosure.

A good example of this is the Adire Brahma, with 28mm Xmax. The speaker is rated for 1600wRMS. The amount of power needed to reach peak output in a good box is actually between 500-600 watts RMS. Anything more than that will just allow the sub to reach full excursion at a lower total system volume. Once you hit the peak output of the sub, all you'll do is run the risk of over-excursion and driver damage.

Sure, at 20hz in an oversized sealed box.

The issue here wasn't suspension limited power handling, it was thermal power handling... the h2 never had enough juice to hit xmax - or even close to it. Its a crappy design that relies TOO MUCH on cone movement for cooling... an extremely weak coil.

And of course in clipping, cooling by cone motion is comprimised. HOWEVER... take a woofer that can actually handle 2000 watts thermally, clip the #&$(*#$ out of it with 1200 watts and it'll go for a good while.

I clipped the living shat out of my compVR's with approx 1000 watts over and over... and all it did was leave me with a stinky coil. Which btw.. the coil is only 2". Turned out to be an amp issue, that fixed itself later on. The h2 would have smoked under those conditions.

You are arguing for a woofer you apparantly have 0 experience with, and its getting pointless.

oh, one more:

There is a fatal error in this statement that prevents me from seeing it as a viable point.
Nobody with half a brain would run a 1200d on a stock electrical system in a car anyway unless they wanted to destroy their speakers, clip their amps, and watch their car lights dim for a while before the car stalls and the alternator fries.
1200 watts class D = ~120A of current draw at full output. Since most cars need at least 60-80+% of their alternator's available current to operate the car, there is no way you'd be using a 1200d and pushing it very hard without some major system upgrades for teh car.
If you do use a 1200d on a stock electrical system and claim to have no issues doing so, you aren't driving that amp very hard at all, or it's wired @ 16 ohms.

He had a yellow top, and solid wire all around. I keep telling him TO THIS DAY to get an alt... but its not happening. He smoked his alt too btw :)

He drove it hard, and got dimmage... but you also have to remember its a regulated amp, so voltage isn't quite as important. Its also *very* effeciant.

He didn't kill his stock alt until he got a 2500d (lmao...) and after he blew his SECOND h2 with it. He was more careful after the first one smoked on the 1200d and ran it fine for approx a year after. Sounded real nice with the 2500d and just got a lil too busy with it one day... ah well.

IMO the h2 needs to have an RMS rating of 800 watts... that seems to be the boiling point for it.

spkrman · Post by **spkrman** » Mon Mar 07, 2005 9:17 pm

nist7 wrote:kiki just owned spkrman into oblivion.

and thanks for all the great info, learned something new today!

Take everything you read with a grain of salt :)

I'll be happy to read the explanation on the whole impedence thing...

Scarrell · Post by **Scarrell** » Mon Mar 07, 2005 9:23 pm

this is getting way off topic and out of hand...

spkrman · Post by **spkrman** » Mon Mar 07, 2005 9:35 pm

Scarrell wrote:this is getting way off topic and out of hand...

All in good fun :)

6three6mafia6 · Post by **6three6mafia6** » Mon Mar 07, 2005 9:54 pm

im personally enjoying it, im sitting taking notes.

Post by **GlassWolf** » Tue Mar 08, 2005 10:22 am

With that attitude... whats the point of NASCAR? Whats the point of racing period? Why bother, who's going to get to 120mph in only 1/4 mile anyway??? whats the point of going in circles over and over and over... why bother?

Ok this one I'll address just for fun. I really dislike NASCAR too. I think its got a redneck following that attracts people purely to watch the crashes with no real care about the actual driving. I also think circle tracks are silly, as I prefer formula or CART type racing if anything, although I've done more with NHRA.
As for a quarter at 120, is 111MPH close enough? That'd be where my car falls in the quarter. Anyway, I still don't see a reason to build a system so loud you can't listen to music in it, and most good SPL systems are tuned to horrible frequencies that make them sound awful anyway. Why? The whole idea of car audio is the audio.. the music.. you want to be able to drive the car, and enjoy it, and listen to music in it.
SPL events are in a sense, like Mr Universe competitions. It's a thing that came from competitive natures extending beyond rationality. If being strong is good, being stronger is better. If being loud is good, being louder is better.. then you get to the point that it goes from being cool to being grotesque.. but sadly by that point you're so engrossed in beating the guy next to you, that you fail to notice when you cross that line, so you just fly across it like thelma and louise right off the cliff.
I've set up SPL cars. I've set up SQ cars. I understand teh physics for both. I just prefer one over the other for personal enjoyment.
Besides, having a decently loud car that sounds terrific, when you get down to it, tends to impress chicks. Saying you have a car you can't even drive, that has a system so loud you can't listen to it, tends to make chicks think you're psychotic and weird. hehehe

If you'd like to come set that up and pay for it... your more than welcome
Its a bud of mine, and I did the install for free - if he were running a more durable sub there would be no issues.

no no see, you pay me to come do that stuff. that's why I'm the professional here! haha
seriously though, if he hadn't abused the system to begin with, he never would have had any problems.
it yet again comes back to proper installation and application, and rational, intelligent use of the system by the owner. This is like killing your dog, then saying well if you'd had a dog that could take more abuse, it wouldn't have died when you kicked it.

I measured 2.2 ohms @ 46 hz (the speakers peak in its enclosure) and the amp was putting out 680 watts. There is no way the impedence fell below 1 ohm EVER in operation, unless something happened while the coil was burning up.

how did you measure this impedance?
this is a ported box, tuned to 46Hz?
how was the amp or sub filtered for both HP and LP?
Before I can give specifics, I need more details.

My initial statement was general and not applied to a specific example. The point was that a "4 ohm" rating on a speaker is purely nominal and the actual AC impedance varies greatly depending on the frequency being produced by the speaker, and the suspension provided by the enclosure at that frequency as well. This will also in turn have a large effect on the actual amount of power the speaker is getting at that frequency.

If you just want to hear some lower frequencies, you'd be better off upgrading your main speakers... no point in getting a 12" sub and an amp if you only need 100db of music.

10mm sub with 100 watts in a sealed box... is gonna be pitiful.

upgrading Ford factory 4x10s or GM factory 4x6s to aftermarket speakers won't gain anything honestly in regards to low end extension. Adding a single short throw 10" sub in single cab pickup trucks is very common and helps extend output a hell of a lot even with moderately low power. Nobody said the box had to be sealed. a box ported to ~34Hz will give great low end response with a good peak at 20-35Hz with natural roll-off. You have a lot of misconceptions about what can be done with low power systems with proper installation. You don't need to use 2Kw of power to hit high volumes, even with good clarity. I ran an IASCA Pro circuit car with 820wRMS total actual power for years and every event I was in the 151.xdB range on the older AC mics, so figure mid 140s by today's standards. That's plenty respectable for a system IASCA rated @ 410 watts RMS and hitting a perfect C weighted curve.

Sure, at 20hz in an oversized sealed box.

Ideal box specs, as provided by Adire Audio. The specs and response are all given on their site, along with the stated recommended power versus thermal power ratings.

And of course in clipping, cooling by cone motion is comprimised. HOWEVER... take a woofer that can actually handle 2000 watts thermally, clip the #&$(*#$ out of it with 1200 watts and it'll go for a good while.

except when the DC voltage causes the sub to extend then stop, which causes a loss of linearity. This causes teh coil to cant, and rub against the magnet structure as it travels, fraying teh coil. Then you get an unraveled coil and a frozen cone once again, thanks to clipping, regardless of how much heat or power was applied. This is why clipping with even 25 watts can destroy a speaker.

[/QUOTE]He had a yellow top, and solid wire all around.

the battery only helps if the engine is off.
you're saying he had solid-core wire?? that was just dumb.

The H2 may very well not handle the power it should, but in every example you've stated, the problem has been caused by something else. Not just the sub itself.

William from NOLA · Post by **William from NOLA** » Tue Mar 08, 2005 1:05 pm

KikiTheCat wrote:the battery only helps if the engine is off.

Actually in my case, I've found this not to be so accurate. There has been an enormous difference between a regular $50-60 battery and my Optima Red Top. I've changed from a Die Hard to an AC Delco with minimal change. In each instance, my lights would dim at higher volumes, even when I had my 180A alternator. Now when I put in the Optima, there is no dimming at all and my electrical system runs fine.

Now, after I have just recently lost my 180A alternator (fricken POS didn't last 1.5 years), I'm running on my stock alternator again and have noticed almost no change in stereo performance. I'm sure the voltage is lower though. With the HO alt, it ran at 14.4, now I'm sure it's around 13.8 or so.

But then again, this is probably just my own case.

William from NOLA · Post by **William from NOLA** » Tue Mar 08, 2005 1:10 pm

KikiTheCat wrote:You don't need to use 2Kw of power to hit high volumes, even with good clarity.

Ditto!

Me: Adire Brahma 15" with 600 rms from JBL 600.1 in a 3.1 cubic foot (internal volume) slot ported box tuned to 30 Hz hitting 141.1 dB on the new TL mic. This is also in a Nissan Quest van.