Top Car Audio Myths...

[Andy Wehmeyer]

Originally Posted by tspence73

I'm with ya here.



I found 25% more wattage than the max rating was a more effective method than using a blanket -10db theory. When I set the DMM to exceed the 55w RMS to 90w on a 0db tone, it seemed to work to give extra volume, but I could STILL detect distortion at the upper range of the volume control where I had the 75% set.

If the amplifier is designed to provide 55W at 4 ohms (14.8 V AC), how do you get it to provide 90 watts--or how do you read 90 watts on your DMM?

[TXwrxWagon]

Originally Posted by quality_sound

Chuckle all you want but that doesn't make you correct. Clipping doesn't kill speakers. Only if the clipping results in over powering the speaker will there be a problem. You can just as easily overpower a speaker without clipping and it'll die just the same. We don't really care why the speaker got more power that it can handle only that it got more power. If you want to follow the silly logic you're using you could blame it on the power wire used for allowing the amp to draw enough current to make enough power to kill the speaker or the RCAs for not limiting the signal, or the bonehead that kept turning up the volume. Really, we can play this game all day long.

ok I was going to take the higher ground... but not so much....

Why in the WORLD would you not care what caused the over power issue? Why would you not want to find the true point of failure?

In your "silly logic"... WTF... its blown... give me a new one... la-la-la... <fingers in ears don't want to hear reality>..... something caused the failure

I didn't say that clipping, distortion or any SPECIFIC thing ALWAYS caused the failure... I simply said that in order to REACH a thermal or mechanical failure SOMETHING causes it... its not just "oh gee... my speaker let the Genie out".....

EDIT * I am asking a serious question here..... what is the ROOT cause of the failure? saying it was "cooked" (thermal) or "maxed" (mechanical) is not the answer... WHY did the speaker fail? why did the speaker REACH that thermal/mechanical limit? I can take the speaker & plug it into a wall socket to get either answer. I can take a torch & heat up the magnet/Vc & get it to fail... what in the signal/power chain failed?

Rob

[tspence73]

Originally Posted by Andy Wehmeyer

If the amplifier is designed to provide 55W at 4 ohms (14.8 V AC), how do you get it to provide 90 watts--or how do you read 90 watts on your DMM?

I set it to 19-volts, which would be 90-watts RMS when on a 4-ohm load. Is that wrong? It seemed correct since I wasn't anywhere near maxing out the gain. In fact, the gain was just a few pinches higher than the 14.8v setting.

[TXwrxWagon]

Originally Posted by Andy Wehmeyer

Fuses and breakers don't know the thermal limits of your speaker. They are designed to open when enough current passes to get them hot enough to trip or blow. IN my experience, speaker fuses are more hassle than they're worth. Either they blow all the time or they don't blow before the speaker is destroyed.

Why all this concern about blowing speakers? In my 25 years as an enthusiast/installer/whatever-the-hell-I-do-now I've never blown a speaker. I've had customers who have never not blown a speaker no matter what i've done to prevernt it.

I know of a competitor who was 1 spot out of a finals spot due to a poor connection on the sub woofer fuse. (looking in the mirror).. lol

back in the IASCA days of flash, displays & excess, you had to fuse anything that had current...

As I said above... i'm just a 40 year old moron, testing 25+ years of audio stupidity.. never a blown speaker... thanks Andy for reinforcing the concept

Rob

[tspence73]

Originally Posted by TXwrxWagon

EDIT * I am asking a serious question here..... what is the ROOT cause of the failure? saying it was "cooked" (thermal) or "maxed" (mechanical) is not the answer... WHY did the speaker fail? why did the speaker REACH that thermal/mechanical limit? I can take the speaker & plug it into a wall socket to get either answer. I can take a torch & heat up the magnet/Vc & get it to fail... what in the signal/power chain failed?

Rob

Speaker reached mechanical limit: Say a 4-inch driver is not made to produce a 20Hz tone at 50-watts but it's rated as a 100-watt driver for it's intended range. The speaker could be pushed beyond it's mechanical limit and cause the cone or material itself to warp or tear apart. Or, a woofer is rated at 40-1,000Hz response and is intended for a sealed enclosure only, and you put it in an infinite baffle instead then try to run it with a 30Hz bass boost at +12db. Likely you will exceed it's mechanical limits with a relatively low wattage and the speaker looks like a party hat afterwards. That would I think be a logical example of exceeding the mechanical limits.

Speaker thermal limit: More wattage is reaching the voice coil than it's designed for, for a longer period of time than it can safely dissapate the heat. The voice coil burns out thermally due to too much input wattage for too long of a time.

So, those are the two ways I figure you ruin a speaker. Either by exceeding it's designed specs and not using it for it the intended application or by exceeding it's thermal limits. Either way, distortion is not likely going to cause a failure as long as the input is limited to the driver's mechanical and thermal specs.

[Andy Wehmeyer]

Originally Posted by tspence73

I set it to 19-volts, which would be 90-watts RMS when on a 4-ohm load. Is that wrong? It seemed correct since I wasn't anywhere near maxing out the gain. In fact, the gain was just a few pinches higher than the 14.8v setting.

That's my point. The amp doesn't produce 19V RMS withut some clipping. Now we have to determine whether you have an RMS meter or not. IF you got a square wave out of the amp designed to provide 14.8 V RMS you'd have 14.8 x 1.4 or 20.72 volts. This us why the DMM method sucks unless you know at precisely what voltage the amp clips.

[quality_sound]

Originally Posted by TXwrxWagon

ok I was going to take the higher ground... but not so much....

Why in the WORLD would you not care what caused the over power issue? Why would you not want to find the true point of failure?

In your "silly logic"... WTF... its blown... give me a new one... la-la-la... <fingers in ears don't want to hear reality>..... something caused the failure

I didn't say that clipping, distortion or any SPECIFIC thing ALWAYS caused the failure... I simply said that in order to REACH a thermal or mechanical failure SOMETHING causes it... its not just "oh gee... my speaker let the Genie out".....

EDIT * I am asking a serious question here..... what is the ROOT cause of the failure? saying it was "cooked" (thermal) or "maxed" (mechanical) is not the answer... WHY did the speaker fail? why did the speaker REACH that thermal/mechanical limit? I can take the speaker & plug it into a wall socket to get either answer. I can take a torch & heat up the magnet/Vc & get it to fail... what in the signal/power chain failed?

Rob

Because the root cause is simple, it was the user turning it up too loud. All of this other crap you're throwing out there is a smokescreen. The final ultimate cause is the owner.

Happy? Jesus fucking christ...

[TXwrxWagon]

Originally Posted by tspence73

Speaker reached mechanical limit: Say a 4-inch driver is not made to produce a 20Hz tone at 50-watts .

no offense Ts... Blah... blah... blah... the those are all givens... too low, to much juice.. the usual...

I am trying, like so many other posts, to give others who are having the issue something to grab on to.. some logic.. if you over extend a 12" woofer with Legacy/Pyramid power... shame on you... no warranty for you!... if you send a 4" coax to below 50hz... I revoke your Driver's license & smack you on the head... those are givens...

but naturally there are failures in well designed/planned systems... what is the REAL failure?

Rob

[tspence73]

Originally Posted by TXwrxWagon

no offense Ts... Blah... blah... blah... the those are all givens... too low, to much juice.. the usual...

I am trying, like so many other posts, to give others who are having the issue something to grab on to.. some logic.. if you over extend a 12" woofer with Legacy/Pyramid power... shame on you... no warranty for you!... if you send a 4" coax to below 50hz... I revoke your Driver's license & smack you on the head... those are givens...

but naturally there are failures in well designed/planned systems... what is the REAL failure?

Rob

I've had a speaker failure because of my own screwup. That was recently when I decided to run a full 0db tone at my speaker's lowest impedance curve to see if I actually needed a load to set the amp gain. I learned I didn't need a load but that knowledge cost me my rear 6x9s because their coils got cooked.

Now as for all the other installs, I would have to say one subwoofer failed because it was defective a year ago. I was pushing it's limits I admit, but I didn't exceed them and it failed. So, that might answer your question. defective equipment. Live and learn.

[FoxPro5]

God I hate the *DMM gain setting method* more than life itself. It's maddening to see people even try and do such a silly thing. Thanks, Andy, for explaining it with figures and relative examples.

[TXwrxWagon]

Originally Posted by quality_sound

Because the root cause is simple, it was the user turning it up too loud. All of this other crap you're throwing out there is a smokescreen. The final ultimate cause is the owner.

Happy? Jesus fucking christ...

Q-SQ... you're a riot... I am chuckling more than when we started...

you FINALLY said what no one wants to say... "no control over their right wrist" or "left wrist" overseas... combined with Deaf ears...

But... you opened the door..(thanks very much)... why would turning the volume up too much cause the speaker to fail?... the thermal & mechanical limits are the final failure... is that say a GAIN problem? a signal/noise problem? a distortion/clip problem?....

You do realize I am egging you on right?

the bottom line to speaker failure is a FAILURE to control the wrist on the volume control past the point where music becomes noise... nothing else.. you can argue "thermal/mechanical" all you want... there is a fundamental failure BEFORE the thermal or mechanical limit of the speaker. Its HUMAN error...

Like soooo many "engineer types" who sleep, jerk off & caress their O-Scopes & DMM... the thing we all seek is an EMOTIONAL attachment to the musical experience... It doesn't matter how much I or anyone else screams "perfection"... if it doesn't sound right... it doesn't sound right, & unless you are trying to please a "judge" in one of the many sanctioning bodies, a person's daily experience has NOTHING to do with thermal/mechanical limits... if he blows up shit... he is blowing up shit... & there is a REASON he is hitting those limits...

education over "theory".... TEACH don't preach...

Rob

[Andy Wehmeyer]

It isn't clipping or distortion. It's simply too much power for too long that causes thermal failure. The cause? The person applying too much power.

The cause of mechanical failure is more difficult to determine unless there's a hole iin the cone or surround. That's why companies will take broken speakers back without a fight but won't often provide warranty replacement for burned coils.

[ca90ss]

Originally Posted by Andy Wehmeyer

That's my point. The amp doesn't produce 19V RMS withut some clipping.

It might if there is no load connected to the amp. Amps generally will put out a bit more voltage before clipping when there is no load on the amp which is generally how people using the dmm method do it to prevent blowing their speakers during gain setting.

[Knobby Digital]

Originally Posted by TXwrxWagon

education over "theory".... TEACH don't preach...

Rob

You're thinking about it the wrong way.

Put a 20w amp on a 2000w sub and clip it all you want. The speakers not going anywhere.

On the other hand give a 20w speaker 2000 watts of clean power and see what happens.

The engine analogy is a bad one because speakers don't need lubrication to function.

[squeak9798]

Originally Posted by TXwrxWagon

Its just funny to me that so many can have such "stanch" opinions like "clipping & distortion don't kill speakers"... then in the same statement its is agreed that exceeding the thermal/mechanical limits IS the culprit... DUH...

When someone is shot with a gun, it's easy to blame the gun itself. After all, the gun killed the person!

But guns don't shoot themselves. They need someone to pull the trigger. So ultimately, while the gun happened to be the method of delivery....the real reason that person was killed via gunshot was because someone pulled the trigger. So is it more accurate to blame the gun for the death (the method of delivery), or the person who pulled the trigger?

In the same sense, clipping may result in excessive power being delivered to a speaker, causing it to exceed it's mechanical or thermal limits and ultimately being damaged. Clipping in this instance happens to be the method of delivery, but it's not the true cause. It only damaged the speaker because the resultant power exceeded the mechanical or thermal driver limits. If it hadn't exceeded one or both of those limits, no damage would have been done.

It's better to explain to someone why the clipping is potentially damaging (due to excessive power exceeding the speaker's limits), rather than just blaming the clipping itself.

As you yourself said....teach, don't preach

Don't preach the perils of clipping without teaching what is perilous about it.

[Andy Wehmeyer]

Originally Posted by ca90ss

It might if there is no load connected to the amp. Amps generally will put out a bit more voltage before clipping when there is no load on the amp which is generally how people using the dmm method do it to prevent blowing their speakers during gain setting.

I think it's far more likely that he was measuring a seriously clipped signal with an RMS meter or measuring peak voltage with a non-RMS meter.

[SublimeZ]

[cajunner]

what is wrong with you people!


edit>


j/k.

[ca90ss]

Originally Posted by Andy Wehmeyer

I think it's far more likely that he was measuring a seriously clipped signal with an RMS meter or measuring peak voltage with a non-RMS meter.

Without using a scope to see exactly what's going on nobody knows for sure what's happening. All I'm saying is that it is possible for an amp without a load to produce more voltage than with a load. Take the linear Power 1002 I tested, it put out 13.91v@4ohm (48.37w) with a load connected before clipping and without a load connected it did 19.6v (96.04w@4ohm) before clipping.

[cajunner]

but did it clip hard, or soft?

at what frequency did you test?

what does phase angle have to do with clipping, and is it better that an amp can produce mild clipping or that it just hits the wall?

[ca90ss]

Originally Posted by cajunner

but did it clip hard, or soft?

Measurements were just before the onset of clipping. There was only a few watts difference between soft and hard clipping.

at what frequency did you test?

I measured at several frequencies but got the best #'s at 1khz.

[evan]

Originally Posted by bigabe

Ok...

diymobileaudio = SQ and ONLY SQ



I can't tell you how many times I've seen people post things along the lines of, "diymobileaudio is an SQ forum"....

Bullshit.

Like SPL guys don't do things themselves???

"Do it yourself" originally referred to combining different speakers from different applications (mostly home audio, some pro audio and car audio) not just installing pre-packaged component sets without the help of a professional installer.

[TXwrxWagon]

Originally Posted by squeak9798

When someone is shot with a gun, it's easy to blame the gun itself. After all, the gun killed the person!

But guns don't shoot themselves. They need someone to pull the trigger. So ultimately, while the gun happened to be the method of delivery....the real reason that person was killed via gunshot was because someone pulled the trigger. So is it more accurate to blame the gun for the death (the method of delivery), or the person who pulled the trigger?

In the same sense, clipping may result in excessive power being delivered to a speaker, causing it to exceed it's mechanical or thermal limits and ultimately being damaged. Clipping in this instance happens to be the method of delivery, but it's not the true cause. It only damaged the speaker because the resultant power exceeded the mechanical or thermal driver limits. If it hadn't exceeded one or both of those limits, no damage would have been done.

It's better to explain to someone why the clipping is potentially damaging (due to excessive power exceeding the speaker's limits), rather than just blaming the clipping itself.

As you yourself said....teach, don't preach

Don't preach the perils of clipping without teaching what is perilous about it.

Squeak... thanks!... that's a perspective I hadn't given any thought too...

Its saying the same thing, but with a different twist I hadn't considered.

thanks again.

Rob

[TXwrxWagon]

Originally Posted by SublimeZ

I need that link.. that's freaking AWESOME!

anyone got one with a sexy chick stirring a pot/cauldron?

Rob

[tintbox]

Originally Posted by unpredictableacts

LOL I always do this even after being told there is no need to......Just incse I do have noice problems I will not have 52 people telling me that that is my problem. I also shake the milk before pouring a glass....My wife used to say that I was going to keep doing it and turn it into butter.....no butter yet.

x2 on that