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PostPosted: Sat Jun 26, 2010 1:06 pm 
the Floor Sweeping Hack with Golden Ears

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ah no it can happen to any amp, just when they are not set up right.



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PostPosted: Sat Jun 26, 2010 1:10 pm 
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a bad wave isnt voodoo magic that casts a evil spell on subs causing it blow though. its just a sqaure wave that is higher voltage then the amps rms power.

i maintain that that amp can't produce enough power no matter how clipped or evil to blow a sub with that kind of power handling and cooling features. the amp will kill itself long before it can send the sub that amount of voltage.

now if the amp blew, and sent straight DC to the sub, thats a different story


Last edited by Bfowler on Sat Jun 26, 2010 5:43 pm, edited 1 time in total.


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PostPosted: Sat Jun 26, 2010 1:57 pm 
the Floor Sweeping Hack with Golden Ears

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I have seen plenty of subs blown from have too small of an amp on it with the volume and gain set too high.

I bet ya $20 and a bad speaker that if you do that test it will result in a blown speaker. Anyone else have a bet? must be shown on video of course...



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PostPosted: Sat Jun 26, 2010 3:47 pm 
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i'm not saying too small of a amp doesn't blow speakers. you are totally right. people clip their undersized amp and put out almost twice its rated voltage, and the sub melts.



what i am arguing is in this case the delta is too great between the voltage that amp can put out, VS what that sub's Voice coils can dissipate

the signal wave a amp sends to a speaker represents the amount of voltage. as you start clipping the signal the wave's peaks are clipped off, so it looks more like a square. as we learned in trig, a square will have almost twice the area as a circle of the same diameter/length. thus a square wave will be almost twice the voltage as a clean wave


so even if that amp was sending completely clipped signal, its still not enough to blow that sub.


the fets in the amp will melt way before the VC in the sub.


if he was using a amp with a rms power closer to the rms rating of the sub i would agree with you.



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PostPosted: Sat Jun 26, 2010 3:50 pm 
the Floor Sweeping Hack with Golden Ears

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k then I will bet you $50 and a blown subwoofer to do the test.



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PostPosted: Sat Jun 26, 2010 4:11 pm 
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It's probably too close on this one for me to start gambling, but by the numbers Fowler's got a fighting chance. Your reasoning is sound for most scenarios Scott, but this very well could be one of the few exceptions to that general rule. The important thing to remember is that a clipped signal itself does not directly cause driver failure. A clipped signal will negatively affect a sub by causing excessive heat build up on the coil and former. But if the thermal capacity of the sub is greater than the peak potential of the amp in question your theoretically out of the "danger zone." The variable that's going to be tough to nail down is DC voltage as has been mentioned.


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PostPosted: Sat Jun 26, 2010 5:58 pm 
the Floor Sweeping Hack with Golden Ears

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dedlyjedly wrote:
The important thing to remember is that a clipped signal itself does not directly cause driver failure. A clipped signal will negatively affect a sub by causing excessive heat build up on the coil and former. .


that is a contradiction right there. By directly, do you mean instantly? Because I can agree that sending it the first clipped signal will not blow it, but it is only a matter of time before that heat is a direct cause of the failure.



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PostPosted: Sat Jun 26, 2010 6:13 pm 
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i dont really think the bet is worth trying to blow either piece of gear.

lets break it down further though. are you disagreeing with my idea entirely, or this specific case of mbquart dsc450 VS RSDC12?


Jed didnt contradict him self. yes, clipping creates heat. the heat comes from excess voltage. but that doesn't mean the sub will blow becasue of it. subs are made to take voltage. its just a matter of how much they can take


for instance, do you think a Sony tape deck blow a mtx jackhammer if we pushed it to the absolute max clipped signal?

could a crappy 50w pyramid amp do it?

a pg m25?

a digital designs m4?

a transformer from the hoover damn?




i guess a similar analogy in my mind is the statement "a electric shock kills people"

your answer seems to indicate, that a AAA battery shocking a person would kill them. becasue shocking a person kills them

i'm arguing that yes, a shock will kill a person, but you will need more then a AAA battery to do it.



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PostPosted: Sat Jun 26, 2010 7:34 pm 

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thanks for all the help - i went ahead and ordered my entire system and think it should be fine if i don't go haywire with it. I will have 200W RMS from the MB Quart DSC 450 going to the RSD Comp 12 at 4 ohm and will not purposely try to blow it up to prove anything :) It's going into a 1 cu.ft. sealed box so maybe this will offer some protection too. The amp was only $87 on sale so I jumped on it, but it was also the right dimensions.

my needs were mostly size/stealth based - i needed 1 amp under the passenger seat to power my front comps and the sub in the WRX hatchback because the main purpose of the WRX is for triathlon training and racing on the track. I like to be able to just unplug the sub and pull it out for a completely empty wagon trunk with little hassle, or else I would just add a dedicated amp in the trunk. I actually have a spare Xenon 400.1 and Cadence 600, but wanted to keep the install bare. Since it's going into a small car and it's a hatchback this should help it sound a little louder right?


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PostPosted: Sat Jun 26, 2010 7:49 pm 
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if you plan on taking your box out often, you might snag these connectors for the box.

http://www.parts-express.com/pe/showdet ... er=092-190

+

http://www.parts-express.com/pe/showdet ... er=092-054

a 1/2 twist removes the male end and you wont ever have to worry about bare connections



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PostPosted: Sat Jun 26, 2010 7:49 pm 
the Floor Sweeping Hack with Golden Ears

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Bfowler wrote:
i dont really think the bet is worth trying to blow either piece of gear.


but from what you said, it will take it all day long so what are you afraid of blowing? I can understand why you do not want to, because you are afraid something WILL happen to your equipment and you are right, just not sure why we went around 4 times to get to this point to agree with me.

I do not understand how you can say clipped signal cause heat build up, and that if heated up enough it can cook a speaker, but that the signal that built up that heat had nothing to do with it? You make is sound like the heat build up has nothing to do signal it is playing and that is just not right.

and cut the crap of putting a jackhammer on the pyramid radios and lets keep this apples to apples. I can agree that there are some subs like the jackhammer and other big spl subs that can hand 110ac from the wall but that as nothing to do with the challenge I laid out to you.

So how big would the bet have to be to see it happen? I am really curious now....



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PostPosted: Sat Jun 26, 2010 8:10 pm 
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ttocs wrote:
Bfowler wrote:
but from what you said, it will take it all day long so what are you afraid of blowing? I can understand why you do not want to, because you are afraid something WILL happen to your equipment and you are right, just not sure why we went around 4 times to get to this point to agree with me.

I do not understand how you can say clipped signal cause heat build up, and that if heated up enough it can cook a speaker, but that the signal that built up that heat had nothing to do with it? You make is sound like the heat build up has nothing to do signal it is playing and that is just not right.

and cut the crap of putting a jackhammer on the pyramid radios and lets keep this apples to apples. I can agree that there are some subs like the jackhammer and other big spl subs that can hand 110ac from the wall but that as nothing to do with the challenge I laid out to you.

So how big would the bet have to be to see it happen? I am really curious now....


i'm not worried about the rsdc, it will blow the amp, and it wont take all day. just turn the gains all the way up, and turn the volume up until one lets smoke out.

how can a clipped signal cause heat build up, and NOT cook a speaker? simple. if the voltage can't produce enough heat to cook the sub.


so you get the idea that it would take a shit ton of heat to cook a jackhammer?

so we agree that subs can take a certain amount of voltage, clipped or not before they blow.

so what we are really disagreeing on is whether the mb quart dsc450 can produce enough voltage(heat) at 4ohms bridged to cook a rsdc before the amp kills itself.

yes?



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PostPosted: Sat Jun 26, 2010 9:08 pm 
the Floor Sweeping Hack with Golden Ears

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if it took this long just to figure out the subj of the challenge then I quit :idiot: :idiot: :idiot: ........



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PostPosted: Sat Jun 26, 2010 11:12 pm 

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I don't understand the physics behind cooking a high quality sub with a poor amp that's under-powered, but out of boredom and some stupidity, I HAVE tried to do this with some spare parts.

In my current Impreza that I'm selling to get the new WRX my above system is being put in, I did a lot of testing before finalizing the install last year. I tried to max out and/or blow up multiple pieces I didn't really care about, but only over a few hour period and I'll list the parts below (only the extremes matter I guess). My brother and I had enough parts from enough cars with enough beers to test some stupid things. (Tested with test-tone CD from 360 to 10 Hz and "bass I love you" track if I recall).

amps:
USAmps 2000W monoblock
Cadence 600
Xenon 400.1
PG Tantrum 400.4
PG Octane 1500

Subs:
Xenon 10D4
Elemental Designs 7" sub in custom box to fix under WRX driver seat
Elemental Designs 10D2
PG RSD 10
PG RSD 12
PG Octane 10
RE XXX 15 (too expensive to screw with so nothing stupid done to this one)

The weakest amp (Tantrum at ~200W bridged) was able to power all the subs to my satisfaction for loudness except the Xenon sub, which required a lot more power than the others to sound even halfway decent. During our few hours of testing, the Tantrum at max gain and volume didn't do anything bad I could perceive to any of the subs. It just sounded horrible with the Xenon. (I think the Tantrum is a much stronger amp than the MB Quart with same ratings however.)

The USAmp 2000W unit could push all the above subs to distortion (they're all pretty cheap subs), and we kept turning the gain and volume up past the distortion point a good amount (but not necessarily to the max point of the amp). The only component that blew up was the Elemental Design 10D2 when wired to 1 ohm and pushed way past specs.

I ended up keeping the Tantrum + RSD 10 combo running for the rest of the year. I kept the amp gain set to max because I figured the amp was too weak for the sub, but from what ttocs is saying, I probably shouldn't have done this as the sub is too powerful for the amp and could have been burned by a bad signal. However, both of these pieces are still in perfect condition after a year of heavy use and in fact, the sub was NOT burned by max settings on a weak amp.

Although I know a lot less than everyone else in this debate, I'm siding with Bfowler's theory. I don't think I can burn an RSD with the weak MB Quart amp. I have the spare RSD 10 that I am willing to risk for this bet and film it since I have no urgent use for it after you guys convinced me to get the RSDC-12 :) Since the RSD 10 is rated at 500W and my amp is rated at 200W, the argument is if I leave the volume and gain on max settings, I should burn the sub correct?

If this is the bet I'll take it - filmed in HD video :) If the sub blows, I lose a $50 woofer. If it doesn't blow you paypal me $50? :)


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PostPosted: Sun Jun 27, 2010 12:50 am 

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OK after all this debate and betting I think I found the answer:

While an under-powered amp is pushed to the point of clipping, it sends more power/heat to the sub... However, the extent of this is directly related to the power of the amp. So, as Bfowler stated, the RSDC can handle so much more power than the cheap DSC450 can push out, clipped or not, you cannot blow it no matter what you do WITH THIS SPECIFIC AMP to this specific sub.

The RSDC can dissipate 600W of average power with peaks of 1200W for a minimum of 8 hours. A 200W amp can clip itself silly and not break this threshold.

I am still willing to take the bet if the statements from the BCAE and JL engineers aren't convincing enough however :)


(from BCAE)
"If your speakers are capable of handling significantly more than your amplifier can produce, driving them with a clipped signal will not likely hurt them.
If the speakers can handle 3 or 4 times the power that your amplifier can produce, there's virtually no way to damage your speakers (no matter how clipped the signal is).
If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a clipped signal for extended periods of time may cause speaker damage and/or premature failure.
If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a square wave signal for extended periods of time will likely cause speaker damage."

(From JL Audio)
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.


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PostPosted: Sun Jun 27, 2010 9:50 am 
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Thanks for putting in the research time to verify the information that has been presented Lawrence. Nice effort. :thumbs:


Last edited by dedlyjedly on Sun Jun 27, 2010 9:56 am, edited 1 time in total.

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PostPosted: Sun Jun 27, 2010 9:54 am 
Briaans..... BRIAAAAANNNNNNS
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i'm so stoked my huge posts weren't in vain for someone!

you seem to get it exactly!

obviously unclipped signal sounds better. but voltage is voltage.

so after all this we can safely assume, you can put your rsdc in a sealed or ported box, and not worry about blowing it.

:clap: hope you enjoy your setup, it should sound nice despite the smaller amp!

do you already have your box? if you dont, and have the space. increasing the box size a bit (1.25 sealed) will help it play lower with the limited power.



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PostPosted: Sun Jun 27, 2010 10:33 am 

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I haven't purchased the box yet, but found one locally that almost fits your specs and looks awesome in this setup. It's 1.3 or 1.4 sealed depending on which store description I look at - you think this will be better than the 1.0?

The pics look kind of cheesy but in person it actually looks very nice and well-built. Going in a rally blue WRX with black/grey interior I think it''ll look sleek.

http://www.proboxrocks.com/products/unl ... ndex.shtml

http://www.topaudiousa.com/servlet/Detail?no=329


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 Post subject: Re: best sub for 200W
PostPosted: Fri Dec 17, 2010 6:35 pm 
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Boston G2 subs are about as good as it gets for mid level price points and performance. Very accurate and surprisingly loud. It convinced me that I needed a G3.


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 Post subject: Re: best sub for 200W
PostPosted: Sat Dec 18, 2010 3:34 pm 
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holy shit its a zombie thread. For the sake of bringing this sucker back to life I have a newly acquired video camera, as well as an xs2300 and an idmax. How long do I have to let this shit play as clipped as I can get it to get some 50 bucks? I needs some christmas money.

Edit: And by the way the bostons g3s are very nice as well.



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 Post subject: Re: best sub for 200W
PostPosted: Sat Dec 18, 2010 6:19 pm 
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i just passed on a minty XS2300 today in box with an og birthsheet. Damn you craigslist!!! it was hard to do but I have too many of these SOB's in the garage already. I have always had a soft spot for the XS amps because they were my first ever owned PG's... they popped my cherry.


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 Post subject: Re: best sub for 200W
PostPosted: Sat Dec 18, 2010 6:27 pm 
the Floor Sweeping Hack with Golden Ears

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Bchester6 wrote:
i just passed on a minty XS2300 today in box with an og birthsheet. Damn you craigslist!!! it was hard to do but I have too many of these SOB's in the garage already. I have always had a soft spot for the XS amps because they were my first ever owned PG's... they popped my cherry.



great man but do you have anything to say that would have to do with the topic at hand :? ?



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 Post subject: Re: best sub for 200W
PostPosted: Sat Dec 18, 2010 7:12 pm 
Briaans..... BRIAAAAANNNNNNS
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Bchester6 wrote:
i just passed on a minty XS2300 today in box with an og birthsheet. Damn you craigslist!!! it was hard to do but I have too many of these SOB's in the garage already. I have always had a soft spot for the XS amps because they were my first ever owned PG's... they popped my cherry.


ditto, love em to death. have way more then i will ever use. where was the 2300? still there?



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 Post subject: Re: best sub for 200W
PostPosted: Sat Dec 18, 2010 9:03 pm 
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Bfowler wrote:
Bchester6 wrote:
i just passed on a minty XS2300 today in box with an og birthsheet. Damn you craigslist!!! it was hard to do but I have too many of these SOB's in the garage already. I have always had a soft spot for the XS amps because they were my first ever owned PG's... they popped my cherry.


ditto, love em to death. have way more then i will ever use. where was the 2300? still there?


yes it's still available and located in SD. total watts= 342. guy wants $70


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