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-   -   Psb 500's, A ticking Timebomb? (http://www.avsforum.com/forum/89-speakers/1458955-psb-500-s-ticking-timebomb.html)

Mik James 02-18-2013 02:17 PM

I have the opportunity to buy psb 500 "tower" speakers for 80$ but the small amount of info i could find on a couple forums suggests there is a design flaw wherein the woofer excursion doubles at certian frequencies causing the spider in the woofer to detach.

So are they safe at reasonable listening volumes?

My setup currently consists of psb 400's and a Kenwood vr 206 reciever, the Kenwood outputs around 50 watts of relatively clean power from what i've heard.
I will eventually be getting a Dayton sub 1200 but the sub will be situated at the back of the room so the 500's would still have to handle bass down to around 40hz.

Thanks in advance.

Bill Fitzmaurice 02-18-2013 02:48 PM

Quote:
Originally Posted by Mik James View Post

I have the opportunity to buy psb 500 "tower" speakers for 80$ but the small amount of info i could find on a couple forums suggests there is a design flaw wherein the woofer excursion doubles at certian frequencies causing the spider in the woofer to detach.
That's not a design flaw, it's what all speakers do. Excursion is not a constant, it rises as frequency goes down. With ported speakers there is a single frequency where the driver excursion is minimal, and the port output is maximum, with the excursion rising above and below that frequency. My guess is that someone saw an excursion chart, had no clue what he was looking at, and made that pronouncement. He was wrong.

Mik James 02-18-2013 03:25 PM

No i know excursion isn't a design flaw and that it increases as the frequency lowers, likely to push more air and keep balanced frequency output.

Here is the thread i found : http://www.canuckaudiomart.com/forum/viewtopic.php?t=26668

At the end of it there is someone who mentioned a large number of repairs due to over excursion on the psb 500's because of mechanical resonance.

I also found a thread where someone bought a pair and believed one of the spiders to have rotted and caused buzzing but it seems more likely it was due to the issue discussed in the other thread.

MalVeauX 02-18-2013 03:41 PM

Quote:
Originally Posted by Mik James View Post

No i know excursion isn't a design flaw and that it increases as the frequency lowers, likely to push more air and keep balanced frequency output.

Here is the thread i found : http://www.canuckaudiomart.com/forum/viewtopic.php?t=26668

At the end of it there is someone who mentioned a large number of repairs due to over excursion on the psb 500's because of mechanical resonance.

I also found a thread where someone bought a pair and believed one of the spiders to have rotted and caused buzzing but it seems more likely it was due to the issue discussed in the other thread.

I would assume since it's hard to find repeat occurrences of this phenomenon elsewhere, over and over, that it's more likely that this is an isolated event and/or just someone's bad luck and their interpretation of blame rather than accepting that it's possible to get something defective perhaps. Maybe just human error too.

I think for $80 you cannot go wrong with what you're trying to do. And I wouldn't worry about it.

Very best,

Mik James 02-18-2013 03:45 PM

Thanks for the help guys and the info about how ports work biggrin.gif
I won't be driving them hard anyways, the room is only 150 square ft.

Bill Fitzmaurice 02-18-2013 04:36 PM

Quote:
Originally Posted by Mik James View Post


Here is the thread i found : http://www.canuckaudiomart.com/forum/viewtopic.php?t=26668
And the poster said 'those 8" woofers go into mechanical resonance with the cabinet at certain frequencies and double their excursions'
That is just plain silly. If a speaker resonated within the woofer passband excursion would be the least of its problems.

Mik James 02-19-2013 09:05 PM

Just got the 500's and threw on the dark knight to see how they handle the lows and how they sound in general. At first i didn't hear much difference and even thought they weren't getting as deep as my 400's but i eventually realized my amp is woefully underpowered for these speakers and they we're actually pushing quite a bit deeper than the 400's (albeit at a lower volume) which is no small accomplishment considering the depth i was getting from the 400's (software eq says 31 hz is audible and clean on the 400's at +3db but i'm not sure how much i trust it tongue.gif )

The overall sound quality is very warm and clear, the guy who sold them bought a set of Klipschs and found them tinny. He was a little reluctant to sell the psb's but i think his wife was the defining factor biggrin.gif

Bill Fitzmaurice 02-20-2013 06:59 AM

Quote:
Originally Posted by Mik James View Post

Just got the 500's and threw on the dark knight to see how they handle the lows and how they sound in general. At first i didn't hear much difference and even thought they weren't getting as deep as my 400's but i eventually realized my amp is woefully underpowered for these speakers and they we're actually pushing quite a bit deeper than the 400's (albeit at a lower volume) which is no small accomplishment considering the depth i was getting from the 400's (software eq says 31 hz is audible and clean on the 400's at +3db but i'm not sure how much i trust it tongue.gif )
No matter how good they are eight inch woofers are no substitute for twelve or fifteen inch subs.

Mik James 02-20-2013 08:19 AM

No of course not, they don't rumble the room with window shaking low frequency bass, but they do sound very clean when producing low frequencies. The only subwoofer i have direct experience with is a vega lw12 and it was built more for power than clean extension.


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