Blown!!!!

audiobliss

Yeah. But if it's causing the problem...then using it is 'wasting it', so to speak.

fortytha12gauge

yea tru but not exactly sure its the problem tho?

MacLeod

Well there is one sure way to find out. Stop using it.

It may not be the cause but something is frying your amps fuses and sending out a wad of power and if your power wire insullation isnt stipped somewhere and arcing out somewhere then the next culprit is the cap.

Its like you feel a really sharp pain in your gut and you look down and there is a hole about the size of a bullet. You look up and there is a guy standing there with a gun. You do the math.

audiobliss

ROFL!!! Man, you've gotten good with the analogies here lately, Mac!!

fortytha12gauge

disconected it. Now just have to wait for speakers to get fixed i hope.

bknauss

PoweredByDodge wrote:

400 rms / 800 max does not mean you can put 800 rms into it.

400 rms IS 800 max... max = peak.

wattage = voltage squared / resistance.

rms wattage = 0.707 * 0.707 * voltage squared / resistance.

0.707 * .707 = 0.5 ... so half.

therefore... 450 rms is 900 peak.

so you were overpowering the speaker.

and don't argue with me, i'm not explaining it any further, get a clue.
.

1. No such thing as RMS power. Its just a bad use of engineering terms that became a "standard". You can have RMS voltage or RMS current, but not both

2. The math isn't right for RMS = .5. Peak*.707=RMS. There's no squaring of anything involved.

3. For amps and speakers, there is no magical math equation to show the relation between peak and average power. You just have to measure it based on CEA-2006 standards and see what the amp does. Some amps will have a lot more peak power than other with the same average power.

4. Call CS and get a replacement woofer. Don't worry about if someone else is saying you overpowered it.

MacLeod

bknauss wrote:

4. Call CS and get a replacement woofer. Don't worry about if someone else is saying you overpowered it.

Well I kinda think he should worry about it a little. This is the 3rd sub he's blown on this system so unless you guys want to ship out a new sub to him everytime he frys one I think its a good idea to try and figure out what is causing the problem.

You engineers think youre so smart just because you went to school for 10 years and are well versed in many theories and physics and can calculate things in your head that most people couldnt.......ok, so you engineers are smart......but....I bet I can drink more beer than you!

neomagus00

eew, i hate beer... vodka is much tastier... or smirnoff... but not beer...

PoweredByDodge

bknauss wrote:

1. No such thing as RMS power. Its just a bad use of engineering terms that became a "standard". You can have RMS voltage or RMS current, but not both

2. The math isn't right for RMS = .5. Peak*.707=RMS. There's no squaring of anything involved.

3. For amps and speakers, there is no magical math equation to show the relation between peak and average power. You just have to measure it based on CEA-2006 standards and see what the amp does. Some amps will have a lot more peak power than other with the same average power.

4. Call CS and get a replacement woofer. Don't worry about if someone else is saying you overpowered it.

1- That's not true. Root Mean Square is a math term, not an electrical term. Apply it to a trig function and you'll get 0.707 or 1/[radical(2)] times whatever you're "rms-ing". now... since "rms-power" is a square of two sine functions, you therefore have to square the rms-factor if you want the rms-factored power... 0.707 * 0.707 = 0.5 ... hence, rms power is half of peak power. rms power is not " 0.5 * 0.707 * peak power".

Note -- Actually -- if you wanted rms voltage and rms current... then 0.5 * 0.707 * peak power would in fact be this "other" rms power... but that's not the standard convention... and as much as I like to buck the system, I've had to succomb to convention, so I guess we all stick with it.

2- see #1 ... it is right. the medium of communication simply does not often enough formatting options to make it look more appropriately written.

3- Rms is not Average... rms voltage is not average voltage... rms power is not average power. While they are virtually identical when dealing with trig functions, pump a triangle waveform through there and then take the same measurement... they're different. Average voltage is the magnitude of the average voltage rating at any given point in time (measured from the beginning of the first upward waveform, through its crest, and until it returns to zero (or whatever its half - waveform point may be, assuming the waveform has an equal duty cycle).

3b - putting aside the debate over sound quality... an amp outputting 20 volts peak AC @ 60 hertz into a 4 ohm speaker (that we will assume for the sake of arguement is at a resistance of 4 ohms at 60 hertz - just for the sake of arguement) will be subject to a draw of about 5 amps... that's 100 watts peak. that's 20 * 0.707 = 14.4 volts rms output... or 50 watts rms output. Average voltage, and thus average power, will roughly be the same because we're using a sine wave. then take a different amp, do the same thing, and you'll get the same result. You can't take a sine wave with a peak to peak voltage of 40 VAC and then somehow say it magically changes.

4- I agree

and.. dun dun dun... 5!

Five would be this... I have no idea how you guys are going about and rating speakers. I've experienced all of the following...

a) "RMS/PEAK" = actual rms and peak... whether you feel its slang or not... rms being used as simply a function of peak... so the speaker can only handle say 500 watts or 250 watts rms.

b) "rms = constant / peak = burst" ... rms being the power you can dump on it all day long while peak would be a brief burst for something like SPL competition... constant use at "peak" rating would damage the speaker.

c) "rms = music / peak = program" ... program material being single note waveforms, while music would be the obvious.. music.

d) "rms = reccomended / peak = maximum allowable" ... both would be for constant muscial listening... the rms would be the MFG reccomended power while peak would be the most the speaker could handle before damage.

...

now if you can tell me which one polk conforms to (or if they conform to a different one than listed) then maybe we'll understand the industry a little better.

bknauss

PoweredByDodge wrote:

1- That's not true. Root Mean Square is a math term, not an electrical term. Apply it to a trig function and you'll get 0.707 or 1/[radical(2)] times whatever you're "rms-ing". now... since "rms-power" is a square of two sine functions, you therefore have to square the rms-factor if you want the rms-factored power... 0.707 * 0.707 = 0.5 ... hence, rms power is half of peak power. rms power is not " 0.5 * 0.707 * peak power".

Note -- Actually -- if you wanted rms voltage and rms current... then 0.5 * 0.707 * peak power would in fact be this "other" rms power... but that's not the standard convention... and as much as I like to buck the system, I've had to succomb to convention, so I guess we all stick with it.

2- see #1 ... it is right. the medium of communication simply does not often enough formatting options to make it look more appropriately written.

3- Rms is not Average... rms voltage is not average voltage... rms power is not average power. While they are virtually identical when dealing with trig functions, pump a triangle waveform through there and then take the same measurement... they're different. Average voltage is the magnitude of the average voltage rating at any given point in time (measured from the beginning of the first upward waveform, through its crest, and until it returns to zero (or whatever its half - waveform point may be, assuming the waveform has an equal duty cycle).

3b - putting aside the debate over sound quality... an amp outputting 20 volts peak AC @ 60 hertz into a 4 ohm speaker (that we will assume for the sake of arguement is at a resistance of 4 ohms at 60 hertz - just for the sake of arguement) will be subject to a draw of about 5 amps... that's 100 watts peak. that's 20 * 0.707 = 14.4 volts rms output... or 50 watts rms output. Average voltage, and thus average power, will roughly be the same because we're using a sine wave. then take a different amp, do the same thing, and you'll get the same result. You can't take a sine wave with a peak to peak voltage of 40 VAC and then somehow say it magically changes.

Wow, so wrong... just so wrong... Everyone please remember what I wrote. Its right. Its been proven for years and years by many engineers.

neomagus00

can either of you provide a reference for the uninitiated, other than your own personal experiences? say, a textbook?

PoweredByDodge

that's what I'm waiting on...

If I'm wrong, then I'd really like to know why and how. I don't need to be going around saying the sky is green when it isn't... it makes me look stupid...

I'm going to put something together... gonna take a little while. In theory - if I'm wrong, then I'll find out when I start digging... we shall see...

MacLeod

neomagus00 wrote:

can either of you provide a reference for the uninitiated, other than your own personal experiences? say, a textbook?

Well, Brian does do this professionally everyday for a major electronics company. While I have the utmost faith in my boy Vinny and would follow him into the depths of hell or at least New Jersey, I have to think that Brian wouldnt state it as such if it werent.

neomagus00

that's what i was thinking, but if memory serves, vinny (vinnie?) is/was an electrical engineering major, so i didn't know who to choose...

PoweredByDodge

school isn't a replacement for practical experience. there's a lot of junk in books that doesn't add up... i picked up more from rebuilding amps than much anywhere else. That being said, Brian has a wealth of experience under his belt.

We're past the "i'm right, you're wrong" stage of this... since neither of us intimidated the other ... lol ...

Seriously though, if i'm wrong, i want to understand why - not to call you on the carpet - but to seriously understand. I was a sponge in another life. A critical sponge, but a sponge.

PoweredByDodge

And I always bring the bat...

Attached is a PDF file... it contains scans of one of my older textbooks as well as recaps of what was argued by each person, and then a "summary" for each item... who was right, who was wrong.

I won't ruin the reading for you yet, but I was wrong about one thing... brian was wrong about one (although I should throw him a bone because he's only "half" wrong... depending on who you talk to "peak" voltage is either 0 to one rail... or rail to rail. being an amp freak, i've stuck to the more strict terminology of peak being 0 to one rail while peak to peak is rail to rail (or local max to next local minimum) buthe busted my balls over average versus RMS power... which he's absolutely right about... so I'll bust his on this... cuz i'm absolutely right on it.)

Topic #3 still has no answer... I don't agree with brian, but I am not totally convinced he's wrong either -- I'd like him to point me in the right direction with it.

#4 we agreed on..

#5 is waiting to be answered..

see the PDF.