LSi9 upper/lower mid-woof drivers - same?

wizzy

Wondering if upper & lowers are the same part / part #

W

Face

I can confirm that on a LSi15 that they are the same part number. I would guess the same for the LSi9/25.

wizzy

I might swap some drivers around.

I bought some refurb LSi9's from Polk off e*bay while visiting up north (had my cousin order them) and got them back here around a month ago. Just got them hooked up and listening to a few different things and I swear I think there may be problems with upper drivers.

It only presents on some limited material so I think Polk may have just "missed it" when refurbing them ... most material sounds fine, but some material gets me a (not so) nice "BRAP" out of the upper drivers on a bass note.

What I did so far is calibrate SPL to just below the "uh, that ain't right noise" and using a pink noise track and an SPL meter.

I can switch between a 35 watt tube amp, an 80 watt HK integrated amp, and a 120 watt HK receiver and regardless of which I use the BRAP sound hits at exactly the same SPL level. I set each amp to the SPL where I know nothing happens, then play the test track and time I know it occurs

Any of the three amps will exhibit the behaviour turned up just a butt hair past this "safe level" --- which seems odd as I would assume if it were amp clipping then the tube amp would hit the limit well before the 120w receiver.

Of course all of the amps are rated to drive 4ohm loads ... and the HK amp ratings above are the power ratings @ 8ohms, at 4ohms they are somewhat higher.

W

ben62670

Both drivers are crossed over at different points. The don not reproduce the same signals;)
Ben

wizzy

ben62670 wrote: »

Both drivers are crossed over at different points. The don not reproduce the same signals;)
Ben

Yes, so I am thinking if whoever owned the speakers before "weakened" the upper mid-bass drivers it would be enlightening to see if I swapped upper/lower if this sound still continued.

I really don't think it is a simple matter of driver being over-driven, or no reason 35w amp should hit it at exact same SPL at 150w amp unless maybe it's just right at some perfect resonant frequency for the drivers.

Pretty much found swapping L/R (flipping interconnect @ amps) both speakers do it.

wizzy

Also I understand that yes I can contact Polk CS but I am trying to do what I can so I don't waste peoples time - trying to diagnose as much as possible before escalating.

W

xj4094dg

Isn't that what warranties are for?

ben62670

Driver 1: LPF at 200Hz 12dB/oct,
Driver 2: LPF at 2.4kHz, 12 dB/oct.
Tweeter: HPF at 2.4kHz 18dB/oct.

One of the mids is a bass driver. If both speakers are sounding the same there is no problem. Think of them as 3 ways, because that is what they are;)
Speakers will slap at a lower power level when the amp loses it's ability to control the drivers.

mmadden28

xj4094dg wrote: »

Isn't that what warranties are for?

Assuming he got them from Polkdirect or another authorized reseller on eBay, yes.

Wizzy, did the LSi9's look brand spanking new when you got them, or did they appear refurbed? Everything I've seen (I have quite a few of them ) or heard about the refurbs from Polkdirect have only been Absolutely new condition.

wizzy

ben62670 wrote: »

Driver 1: LPF at 200Hz 12dB/oct,
Driver 2: LPF at 2.4kHz, 12 dB/oct.
Tweeter: HPF at 2.4kHz 18dB/oct.

One of the mids is a bass driver. If both speakers are sounding the same there is no problem. Think of them as 3 ways, because that is what they are;)
Speakers will slap at a lower power level when the amp loses it's ability to control the drivers.

So, is the top driver the one crossed at 2.4, or the lower?

The top is the one that "slaps"

It does seem odd all three amps (one a low powered tube) would all crap out at exactly the same point.

Have Bryston 3B-ST arrived today, but in storage as I might go shooting off to Key West for a week. In which case sometime next week (7-10 days) I will try it.

Came out of box looking pretty new, no chinks in the piano black.

Steve

Face

Lsi9's do drop down to 2ohms, maybe that's the spot they're all having trouble.

Systems

wizzy wrote: »

So, is the top driver the one crossed at 2.4, or the lower?

It's the upper one that covers the midrange up to the xover point with the tweeter.Both woofers work in parallel below 200hz,thus the reason for the difficult load.Technicaly its a 2.5 way.

wizzy

Found this imped graph

Systems

It does appear to drop into the 2-3 ohm range at 50hz.

wizzy

GV#27 wrote: »

It does appear to drop into the 2-3 ohm range at 50hz.

Thinking about this though, then why wouldn't I hear both woofers crap?

I'm not sure what Hz it's doing it on, but if it's below 200Hz then both of them should get it ... and much above 100Hz we are back to a good 4ohms.

Hmmm

wizzy

Here is a clip of the sound file, it's is a zipped wave.

The offending sound comes in right at about the three second mark.

Almost attached a 30 second MP3 extra, but decided to remove it as I didn't want to hit some copyright issue.

W

Systems

wizzy wrote: »

Thinking about this though, then why wouldn't I hear both woofers crap?

I have no answer.


Aswell my eval version of winzip is expired so I can't hear your clip.

wizzy

Who needs winzip:

http://www.7-zip.org/

Free, and does more

Systems

wizzy wrote: »

Who needs winzip:

http://www.7-zip.org/

Free, and does more

Awesome thanks,I hate always having to reregister with winzip.


I couldn't hear anything unusual in your clip,but on your 9's does the problem only occur with this particular track?

wizzy

GV#27 wrote: »

Awesome thanks,I hate always having to reregister with winzip.


I couldn't hear anything unusual in your clip,but on your 9's does the problem only occur with this particular track?

So far as I haven't exactly had them out long enough to work through a litany of selections. I would imagine I could find some more tracks, probably anything with a bass (say stand up, acoustic bass) theme.

I did find out I won't be hitting Key West this week so now I can try out the Bryston ...

W

Face

http://www.realtraps.com/test-cd.htm

Systems

wizzy wrote: »

So far as I haven't exactly had them out long enough to work through a litany of selections. I would imagine I could find some more tracks, probably anything with a bass (say stand up, acoustic bass) theme.

I did find out I won't be hitting Key West this week so now I can try out the Bryston ...

W

I have a Pat Metheny/Charley Haden disc that in one or two sections I hear distortion for a very brief transient with Haden's stand up bass.This happens on the midrange driver only of a 3way triamped active system.I guess that individual note is so demanding that it causes the 100watt amp driving the midranges to clip, even at reasonably normal listening levels.
So your problem may be the content of the CD itself?When you hook up the Bryston watch the clipping LED's,if they flash on that section of music then you'll know thats the case.