PSW article on blown speakers, underpowering

[agedhorse]

The assumption is "reasonable" levels, and that's my point. Sure, powered speakers have "clip limiters", and many amps have the same, but remember that poor guy who posted here a while back about having "blown" his JBL PRX subwoofers ???? Those have built-in limit protection, and amps designed by JBL to power those subs, yet he still "blew" them, and he got blamed for "operator error" ?????????????????????????

 

 

We never found out what really caused the failures. Remember that I asked several times for more details but never got them. Could have been a power source problem (like an open neutral causing the input voltage to swing up real high), a user problem, a mechanical problem (got tossed during shipping) etc.

 

For as many of these as have been shipped, the failure rates appear to be very low. You are all on board to blame the speaker, I am not quite so quick to judge because I don't know all the facts.

[agedhorse]

If this was a forum thread, I'd say "yup", but it's an article in their "Study Hall", which we're supposed to think is good information that's been reviewed by the (paid) editors of PSW. There is at present one (1) comment on it, and it's a "me too" anecdote.

 

 

I agree, for a "factual article", it's IMO terribly misleading and inaccurate. Doesn't do anybody any good to learn from bad info.

[Bobby1Note]

We never found out what really caused the failures. Remember that I asked several times for more details but never got them. Could have been a power source problem (like an open neutral causing the input voltage to swing up real high), a user problem, a mechanical problem (got tossed during shipping) etc. For as many of these as have been shipped, the failure rates appear to be very low. You are all on board to blame the speaker, I am not quite so quick to judge because I don't know all the facts.

 

 

Andy,

 

I'm not necessarily blaming the speaker; the point is, the guy thought he was protected with built-in limiters/ properly sized amps,,,, but it wasn't the case. If you recall; he had inadvertently run the subs "out-of-phase".(which shouldn't have mattered) If I remember correctly, it was also pointed out that he may have "clipped" the mixer, but he saw no indication of that. Any AC power issues are purely speculative, but obviously "possible". Operating his tops however, posed no problems on the same AC power.

 

It seemed to me in that thread, that every possible "other" fault "might" have been to blame for this guys' problems, rather than the speaker limit-protection malfunctioning, or, being improperly or incompletely designed.

[srp72ee]

Andy, I'm not necessarily blaming the speaker; the point is, the guy thought he was protected with built-in limiters/ properly sized amps,,,, but it wasn't the case. If you recall; he had inadvertently run the subs "out-of-phase".(which shouldn't have mattered) If I remember correctly, it was also pointed out that he may have "clipped" the mixer, but he saw no indication of that. Any AC power issues are purely speculative, but obviously "possible". Operating his tops however, posed no problems on the same AC power. It seemed to me in that thread, that every possible "other" fault "might" have been to blame for this guys' problems, rather than the speaker limit-protection malfunctioning, or, being improperly or incompletely designed.

The out-of -phase should have only cancelled sound out in the room, not destroyed the speaker. Clipping the mixer might do it.

Since I haven't seen any manufacturer advertise a "burn out proof" powered speaker, I can only assume if you put the correct individual behind the wheel that anything is still possible.

[IsildursBane]

The out-of -phase should have only cancelled sound out in the room, not destroyed the speaker.

 

 

It would if he drove the hell out of the speakers to try to compensate for the phase cancellation.

 

-Dan.

[srp72ee]

drove the hell out of the speakers

 

 

That probably caused it...

 

 

Out of phase would have "tricked" his ears at certain frequencies, but not the entire sub spectrum.

[Craig Vecchione]

 

It seemed to me in that thread, that every possible "other" fault "might" have been to blame for this guys' problems, rather than the speaker limit-protection malfunctioning, or, being improperly or incompletely designed.

 

 

Did you raise that possibility?

[Bobby1Note]

It would if he drove the hell out of the speakers to try to compensate for the phase cancellation. -Dan.

 

 

Theoretically impossible,,,, they were limit-protected.

[Bobby1Note]

Did you raise that possibility?

 

 

I don't recall CraigV, I'm pretty certain that subject was discussed, but I don't recall who initiated that conversation.

[jwlussow]

I have a question. I am now concerned that I may be damaging my speakers or amps because of underpowering. I am using a Crown K1 in stereo to a pair of MRX518 subs. I can

[dedmeet]

I about puked when I read:

The cone moves out, pauses momentarily, moves back in, pauses momentarily, moves back out, pauses.. you get the idea.

Folks, this is basically the same argument as the folks who try to claim the flattened tops of a clipped sine wave or square waves are DC. It just is not true. While we are at it it Clipped Sine wave square wave and The flat top of a square wave DC.

Anyone who knows basic calculus has done this math a billion times. Anyone with an oscilloscope can prove it for you.

It is really simple: when a wave form clips, it substantially increases the actual power content of a wave form. So, your amp may produce 200W with a clean 1KHz sine wave, but a distorted wave form can increase the effective power output by more than double.

Two things kill a speaker: too much power and exceeding the mechanical excursion limits of the driver. Period, done.

[Craig Vecchione]

 

I don't recall CraigV, I'm pretty certain that subject was discussed, but I don't recall who initiated that conversation.

 

 

I may be confused about what you're driving at then. You seem to be implying that the forum was only accepting one possibility; that the OP had done something wrong. I recall him asking what he might be doing wrong or need to change, and that a lot of ideas were floated, there were several unanswered requests for info from the OP, and that no conclusion was drawn.

[Craig Vecchione]

 

I about puked when I read: Folks, this is basically the same argument as the folks who try to claim the flattened tops of a clipped sine wave or square waves are DC. It just is not true. While we are at it it Clipped Sine wave square wave and The flat top of a square wave DC. Anyone who knows basic calculus has done this math a billion times. Anyone with an oscilloscope can prove it for you. It is really simple: when a wave form clips, it substantially increases the actual power content of a wave form. So, your amp may produce 200W with a clean 1KHz sine wave, but a distorted wave form can increase the effective power output by more than double. Two things kill a speaker: too much power and exceeding the mechanical excursion limits of the driver. Period, done.

 

 

I was starting to compose a post about this as well, but realized how useless it would be to post here.

[Harmonycat]

There are a few asses there

They are relatively easy to spot.....


They are the guys who talk about themselves in the third person, and have the GOD complex.


People who missed "Social Sandbox" while growing up


:lol:

[Craig Vecchione]

George is getting VERY ANGRY!!!!:mad:

 

 

[mshifflett]

Don't touch Jimmy

[Craig Vecchione]

Don't touch Jimmy

 

:lol:

[Axisplayer]

If this was a forum thread, I'd say "yup", but it's an article in their "Study Hall", which we're supposed to think is good information that's been reviewed by the (paid) editors of PSW.

My comment wasn't about that article but about the value of PSW in general. I think the particular article is misguided, but I think PSW does have a LOT of smart folks. This just wasn't their finest hour.

[NUSound]

My comment wasn't about that article but about the value of PSW in general. I think the particular article is misguided, but I think PSW does have a LOT of smart folks. This just wasn't their finest hour.

PSW serves as a source for really high-end production. Here at HC, most of us (myself included) fit into the small-beans category compared to several of the regulars in the LAB. Is this bad? No, but they attract a lot of wannabe riff-raf because of it, which is why several of us avoid the 'other' forum.

[Unalaska]

I like the info on PSW for the high end users. There is a lot of detailed questions that are so far up the complexity food chain we'd never see them here or on another end user site. Unfortunately in the lounge there can be a lot of mis-information (by users) and those trying to be bigger than they are.

This forum has a much easier interface too, easier on the eyes to read and the people are generally pretty nice.

The subject matter though can be debated till amps become obsolete along with copper and paper speakers in 100 years. The premise of underpowering relies on the idea that there isn't enough rig for the gig and what is there is being driven into clipping. If it isn't being driving into clipping would it still be called underpowering? Last I checked all speakers are passive devices that only do something when electricity is applied, no speaker "wants" anything. I'd even argue the speaker "wants" to be at rest and the very act of moving them causes them to speak loudly in protest...

[Gregidon]

The subject matter though can be debated till amps become obsolete along with copper and paper speakers in 100 years. The premise of underpowering relies on the idea that there isn't enough rig for the gig and what is there is being driven into clipping. If it isn't being driving into clipping would it still be called underpowering? Last I checked all speakers are passive devices that only do something when electricity is applied, no speaker "wants" anything. I'd even argue the speaker "wants" to be at rest and the very act of moving them causes them to speak loudly in protest...

 

 

That's awesome! I like that - 'speak loudly in protest'. It is one of my pet peeves as well when someone says that a speaker "wants this" or "wants that". Speakers will handle certain power levels and achieve particular performance at those power levels, but if the volume is not demanded a speaker driven by a good quality lower power amp will sound indistinguishable from a speaker driven by a good quality higher power amp.

[dboomer]

This article appears to be written by somebody who has no understanding about failure modes in modern loudspeakers.

 

 

Yep.

 

Speakers do not pause momentarily at the extremes of excursion (unless they actually hit something)

[srp72ee]

Speakers do not pause momentarily at the extremes of excursion (unless they actually hit something)

Like the front grill!

[agedhorse]

Theoretically impossible,,,, they were limit-protected.

 

 

Limiters are not foolproof. Every time we develop better and more foolproof protection, the fools get even better at it.

[agedhorse]

So, your amp may produce 200W with a clean 1KHz sine wave, but a distorted wave form can increase the effective power output by more than double.

 

 

Square wave = 2x the same amplitude sine wave (maximum). Can't exceed this.