Underpowered speakers?

heiney9

I know you came down to Rockton to pick up Rob's TT. There is a friend of ours (Rich, Rob and myself) Daboyz that has his LSi 15's for sale here in Rockford if you'd feel more comfortable coming back down to demo them and purchase. I've personally heard them several times and they are very nice and minty

http://www.polkaudio.com/forums/showthread.php?130579-Lsi15-s-Ebony-w-Gray-panels

Just a thought

H9

FTGV

ravaneli wrote: »

My short reply is BULL.

I don't know who came up with this bull about underpowering speakers being harmful, but it is total bull.

I offer you this excellent take on the subject.http://www.jblpro.com/catalog/support/getfile.aspx?docid=246&doctype=3

heiney9

Fred, that should be a sticky. Hopefully Ravinelli will read it and understand how his statements aren't true.

H9

SCompRacer

I know someone who called Polk many years ago after blowing some tweeters and they told him he needed more amp. The guy I bought the SRS 2's from. He wrote notes in the speaker manual he had, the one that Matt signed for me. The guy bought not one, but two Adcom 555's and never blew a tweeter again.:cheesygrin:

62caddy

An amplifier that is not overdriven cannot damage speakers regardless how low the power rating.

A high power amplifier absolutely can damage speakers.

Each case is unique with innumerable variables.

To dismiss, out of hand a pair of speakers on the basis that they were used with a "6 ohm amp" (whatever that is) is prejudgemental and flawed IMHO.

Geoff4rfc

62caddy wrote: »

An amplifier that is not overdriven cannot damage speakers regardless how low the power rating.

I'm pretty sure most here are on par with your statement, what's taking painstaking effort to convey is that an amp that IS overdriven can result in speaker damage.

ravaneli wrote: »

I am no engineer, or speaker guru, but they did teach us some basic physics laws at school in my country. I know in this country things like physics and math are not mandatory and people prefer taking sociology instead, but this is no excuse here.

I'm just curious to know what country ignores scientific fact and calls it myth :eek:

Erik Tracy

I'm on record as one that from first hand experience knows that overdriving an underpowered amp will kill tweeters.

As a lad in the 70's in the quest for dBs, I fried tweeters in my speakers like they were Doritos (good thing they made more) when cranking up my underpowered Sansui receiver. (The speakers were rated to handle more than my Sansui could deliver, yet I failed to learn that 'stupid loud' meant burning out the tweeters from over driving the receiver into distortion).

I still have a tweeter that was melted from driving the amp into distortion and frying the tweeter.

Power is your friend.

FTGV

I think your circuit is oscillating.

bobsauto49

I'm still waiting for ravioli's response on this matter!!! After all, I read CP for the humor!

FTGV

bobsauto49 wrote: »

I'm still waiting for ravioli's response on this matter!!! After all, I read CP for the humor!

The mod's removed his "response".I'm not sure one should frequent an audio or any other forum if it causes one to react in such an extreme manner.

jbooker82

FTGV wrote: »

The mod's removed his "response".I'm not sure one should frequent an audio or any other forum if it causes one to react in such an extreme manner.

Why I dont think it would have made any of us cry.

BlueFox

This whole underpowered speaker discussion seemed to be a "failure to communicate'. Nobody would say that using a 20W amp would cause speaker damage in and of itself. Using a 20W amp to try and make ear bleed SPL levels will.

When I bought my first pair of LSi15s ten years ago I used them with the bottom of the line Sony AVR, DA-1ES.

•100 watts x 5 into 8 ohms (20-20,000 Hz) at 0.09% THD
http://www.crutchfield.com/S-bG1Aw8NPxDj/p_158STRDA1E/Sony-ES-STR-DA1ES.html#overview-tab

Anyway, they sounded great then, and still do today. Over the years, I did three AVR upgrades with each one being a bit more powerful, and I use the current AVR as a pre/pro with the Sunfire TGA-5400 amp.

BeefJerky

FTGV wrote: »

The mod's removed his "response".I'm not sure one should frequent an audio or any other forum if it causes one to react in such an extreme manner.

jbooker82 wrote: »

Why I dont think it would have made any of us cry.

I missed the response, however, your description of it doesn't surprise me. Personally, I would've rather it stayed so that everyone could see his/her true colors. Nonetheless, I understand why the mods would remove the post.

tonyb

Well, I'll chime in one more time since his response was aimed at me.

First though, to the OP, I want to appologize for all the huppla, we aren't normally like this. This is however the internet and sometimes this stuff happens. Seeing that the guy you want to buy the speakers from is willing to let you bring something over to hook up and listen says alot. Take him up on it, you'll feel better too should you decide to purchase.

Rav,
It doesn't bother me that you disagree with me, god knows alot of us disagree with each other around here, but you have to keep things civil man. Polk gives us alot of latitude in our discussions, providing we keep things discussed in a civil manner. I for one am gratefull for the space Polk gives us on this board but also realize gifts can be taken away. I have no wish to see you banned, or anyone else for that matter. We can all learn together without attacks. I'll throw out the olive branch for the sake of moving on and we can just chalk it up to having a bad day. Cool with you ?

62caddy

BlueFox wrote: »

This whole underpowered speaker discussion seemed to be a "failure to communicate'. Nobody would say that using a 20W amp would cause speaker damage in and of itself. Using a 20W amp to try and make ear bleed SPL levels will.

This isn't necessarily correct either: Ever listen to a 20wpc amp with a pair of 105 dB speakers?

steveinaz

BlueFox wrote: »

This whole underpowered speaker discussion seemed to be a "failure to communicate'. Nobody would say that using a 20W amp would cause speaker damage in and of itself. Using a 20W amp to try and make ear bleed SPL levels will.

Exactly. It's when you push an under powered amp into clipping that bad things happen. As I stated earlier, if you're listening at moderate levels there won't be a problem, assuming the amp is rated to operate at the nominal impedance of your speakers.

ravaneli

Hmm.. my response has been removed even though I didn't use offensive language. Calling people an idiot appears to be allowed and popular however. All the losers with IQ a lot lower than mine, that have never achieved anything in life line up to throw insults in an internet forum where they for once in their life can pretend to be a man.
Anyhow.. not a big deal, seen that type before and it doesn't really break my heart.

This is my last post in this thread anyway, because I don't think any logic or law can be used to convince you otherwise. I read some of those links, carefully, and there was nothing there that contradicted what I said.

Everyone here is confusing the symptoms with the real cause, and nobody has any independent judgment or engineering knowledge to separate them. See, there is a very high correlation between the number of churches in a town and the number of bars. Does that mean that religion causes drinking? Well, it turns out that the real factor that is driving the number of bars and churches is the population of the town, bigger towns have more churches and more bars.

Clipping and speaker damage often go along together and people attribute the damage to the clipping and nobody cares about the real culprit, which is overpowering. The difference between clipped signal and normal signal is that the clipped signal is a heavier load than the normal signal. An amp that is sending clipped signal is sending more power than if it were to send the same signal normal. In that respect it is possible to have an amp with 100Wpc overpower a 150W rated speaker, because if you push the amp to the limit it can clip the signal and send power higher than spec. But it is the POWER that damages the speakers, always!

I mean there has to be at least one person here that can understand this. Clipped signal itself is nothing. You can send 10W of pure clipped signal to a 150 W rated speaker. You can record pure rectangular signal but send a 10 w power to the speaker and you will not damage anything. Clipped signal = higher power than regular signal = heavier load for the speakers, but it is still just a load. And the only way for clipped signal to destroy a speaker is for the clipped signal to be of higher power that what the speaker is rated for, but even then it is not the clipping, but the power that destroys the speaker.

In most cases the clipping is far from extreme. I mean you have to be deaf not to hear that the signal is severely distorted and stop pushing the amp. So when the first answer on this thread said 'I would pass on these', when the receiver was SO FAR from the power handling of the speaker, and the owner didn't even push it, you have to realize this is very bad advice to the OP, who could pass on a great deal.

So that is that, you can keep living in your world of anecdotal evidence, or you can for once try to make sense of things, but it's really up to you, and I promise I couldn't care less if you disagree..

heiney9

Remind me never to buy any speakers from you. Clipping is bad juju and should be avoided not only because it sounds bad, but it does damage. So for you to post that it's ok tor drive an amp into distortion is ludicris really. That's like saying it's ok to run your car into a wall at 30mph because you won't die, but don't run it into the wall at 80mph because you will die. Both are bad scenario's that should be avoided.

What a very strange view you have, distorted (pun intended) really.

H9

hochpt21

Alright here we go....

I take a buddy and we go over to the guy's house last night. He and his wife invite us in and offer us a drink. He has the 15s ready with an audio rack and a cd player in between. Cosmetically, I would have thought they were new other than the fingerprint smudging on the piano black part of the speaker. I bring in my hk and bk and hook everything up.

First track is "Breathe" from Pink Floyd's live "Pulse" album. Second, is "Black" from a Pearl Jam live album. Next, I wanted to really focus on the bass since my plan would be to get rid of my sub...so I put on a Slick Rick cd from back in the day. I took the grills off both speakers and listened to each driver and everything sounded clean and clear.

Now 10 minutes isn't enough (for me) to really analyze what I was hearing and why, but it was enough to tell that I really liked it.

I asked him various questions and it turns out he works at a big-box electronics/furniture store. He said that he upgrades his speakers every year or two because of the discounts that he gets. Now he wasn't an audio guru, but clearly understood the whole clipping/distortion thing and was very confident that the speakers were in good shape.

All in all, I felt very comfortable with the seller and the info he gave me. The speakers looked and sounded beautiful. Needless to say, they went home with me.

Thanks for all the input and sensible advice

P.S. When I asked him what he upgraded to, he pointed to a pair of LSiM 705's. I told him to let me know the next time he upgrades:eek:

chumlie

Congrats on your new speakers.

heiney9

Only advice I can give on the LSi15's is placement IS critical to get the best bass performance out of them. I doubt they will have enough "umph" to replace your sub if that's what you are used to and prefer. LSi 15's don;t put out that kind of bass. All you can do is experiment, but just be aware placement is the key to get the best performance out of them.

Good luck

H9

62caddy

Congrats. Sounds like you did well in all ways- pardon the pun. :cheesygrin:

BTW: Was there by chance any warranty left?

hochpt21

10-4 I will experiment with placement. It was a compromise with the family to get the sub out of the living room, and I didn't have it turned up too loud anyways, so I am hoping the 15's get me close to where I need to be.

BTW thanks for the thought with the other 15's in your earlier post.

Drenis

Sounds like it went alright. Good pick up!

heiney9

hochpt21 wrote: »

10-4 I will experiment with placement. It was a compromise with the family to get the sub out of the living room, and I didn't have it turned up too loud anyways, so I am hoping the 15's get me close to where I need to be.

BTW thanks for the thought with the other 15's in your earlier post.

I think you will enjoy them a lot.

H9

steveinaz

You can lead a horse to water, but you can't make him think...

There's only one thing worse than being wrong, and that's being wrong, confidently. LOL.

Geoff4rfc

ravaneli wrote: »

Everyone here is confusing the symptoms with the real cause, and nobody has any independent judgment or engineering knowledge to separate them. See, there is a very high correlation between the number of churches in a town and the number of bars. Does that mean that religion causes drinking? Well, it turns out that the real factor that is driving the number of bars and churches is the population of the town, bigger towns have more churches and more bars.

This is what happens when you blindfold a chicken, shake the crap out of it, and let it gooooooooooooooo

steveinaz

He needs a Midol, and to register for Electronic principles, 101.

Joe08867

To the OP, Glad you are happy with your purchase. Sounds like you did good.

Ravenli, so three different guys give you information that polk supplied and you still think distortion is harmless. You sir are wrong and a little silly in your pursuit of this argument. There are plenty of places to go to find out how wrong you are, but I won't be giving you links cause you won't read them anyway. And that makes this argument useless. So have a good day and remind me never to purchase audio equipment of any kind from you. Thanks,

Dennis Gardner

I'm willing to give "R" credit for the further explanation, but have to call him/her out for trolling with the original post in the first place without qualifying the statement. Classic hit and run trolling.

It is truly a chicken/egg situation since clipping the power amp is the cause of harmonic destruction of tweeters due to overheating the VC. Overpowering can't exist without the clip in an underpowered amp, and the harmonics don't exist within normal (unclipped) waveforms.

If distortion at any level were capable of blowing speakers regardless of power, no electric guitar amp speakers would last past its first session, with the preamp driven into full blown clipping.

To over simplify that all/any clipping/distortion is bad is just as unfair.

Just as unfair as the 200WPC requirement statement that seems to get posted to death around these parts.