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#177085 - 09/21/07 03:53 PM Help, what have I done !! EP500 has a rattle.
Murph Offline
axiomite

Registered: 10/05/06
Posts: 6955
Loc: PEI, Canada
First off, I admit I have been tinkering with my receiver settings lately. However, I may have been noticing this for a while before but was blaming the wooden shelf not far from it. Hard to know for sure now.

I'm calling it a rattle for lack of a better term. At first it sounded wooden, as above. However, it grew bad enough I brought my head over in front of the driver and it seems to be produced by the driver. When you are close and looking at the driver, it gives you the feeling that the rubber diaphragm is making a vibrating, flapping noise. However, this could be an illusion, influenced by the fact that I am watching this big rubber ring vibrate mercilessly in and out.

It occurs in the very low LF effects in movies and very deep bass drums in certain music. Increased volume definitely increases it's presence but it is also present in really low LFE at very moderate volume levels. As long as there is that prominent LF that it has to work hard on doing the lows, its there.

Chance of abuse as the cause is honestly minimal. I'm not a screamin loud kind of guy. Even for movies where I really want to stress effects, it's usually 75 to 80 db averages and some spikes into the nineties. If someone really wants to hear a loud demo, I'll give them the volume control but I shut them down if the peaks are breaking low triple digits. (I always take out the meter during demos so I have that exuse plus...I'm a geek. :-) I don't think I ever gave the sub more than it could handle. Maybe when I first tested it out but even then Im sure it can handle more than my ears can.

EP500 is running off a Denon 3608. I confirmed that these settings are back where they normally are.

- Denon's set for zero DB adjustment on the sub. All other speakers calibrated to equal levels.
- Sub distance is set to 13' (have tried larger numbers and I almost think it helps mask the rattle so I left it at 24' but its normally 13)
- Set for LFE, vs. LFE & Main

- Sub 'rattles' worst when set to full. Currently set to Flat where there is less rattle.
- Dial on the sub has always been at around the 9:00 position. I'll play with it a bit depending on seating but that's the norm. 9 o'clock gives me decent bass in my sweet spot but is too much in the corners of the room. (Square, hard room)

I can see no visible damage to the outside of the driver, I have put pressure on areas like the port and sides to see if it is something vibrating there but it honestly doesn't sound like a box vibration. Gives the impression it's in or around the driver materials.

Another symptom I noticed is that when I try to check the DB calibration and play a test tone with Avia CD, the meter wavers up and down by up by a variable of up to 5 db plus or minus. It's digital so it's hard to tell if its an even, 'sine wave like', up and down but I would think I should get a more solid reading.
Note: The sub tones on Avia are set up to play alternating against the other speakers but it is just during the sub tone that I am still not getting a solid reading. Perhaps this is normal?

Sorry too much info probably but I'm hoping the hard core readers will have some advice as to what I might check on. I'm open to further probing questions if you think you can help.

I'd like to rule out that I didn't make some other change to my setup or at least get the advice from the experts here before I start down the path of deducing my sub may be having issues.

Thanks all!
_________________________
With great power comes Awesome irresponsibility.

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#177086 - 09/21/07 04:05 PM Re: Help, what have I done !! EP500 has a rattle. [Re: Murph]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13571
Loc: Iowa
Not sure, the only thing is you may be running the sub to hot on the volume (gain) control. On my Denon 2805 with EP600, to calibrate at 75dB with my SPL meter the knob on the sub is at about 6-7 o'clock, and the receiver is at around -6dB's. If I put my Denon on 0db and the volume gain on the sub at 9 o'clock like you, it would be way to high and the woofer would be going nuts.

I think my receiver would have to be on about -12dB with 9 o'clock sub setting to get 75dB on the meter.
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M80s-VP180-4xM22ow-4xM3ic-EP600-2xEP350
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#177087 - 09/21/07 04:22 PM Re: Help, what have I done !! EP500 has a rattle. [Re: SirQuack]
Murph Offline
axiomite

Registered: 10/05/06
Posts: 6955
Loc: PEI, Canada
Hmmm, Has me thinking....
You may or may not remember a while back I posted asking questions because I found an obscure Denon feature that set the sub back an additional 10db. This is a setting on its own, not the general speaker level settings. The manual mentioned something about the idea that you needed 10db less for DTS recorded material.

I wonder if I didn't bump that up to zero when I was playing with it and leave it there?

That would explain why I previously seemed to require 9 on the dial to get heavy base in my listening position before but now it is too much.

I should mention that i did do the obvious tests of turning down the dial substantially and the rattling was still there but I may not have gone back far enough to compensate for the additional 10 db I'm getting from that feature.

I'm betting your synopsis is correct in that it's now running hot but it wasn't before because I was losing 10db from that odd setting.

Thanks! I'll check this when I get home. Hopefully, this is all it is and no permanent damage was done.
_________________________
With great power comes Awesome irresponsibility.

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#177088 - 09/21/07 04:35 PM Re: Help, what have I done !! EP500 has a rattle. [Re: Murph]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13571
Loc: Iowa
I do remember something about that post you mention. I'm curious about that setting if it is on my Denon 2805, hmmm
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M80s-VP180-4xM22ow-4xM3ic-EP600-2xEP350
Anthem AVM60 Outlaw 7700 Emotiva A500 Epson 5040UB



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#177089 - 09/21/07 04:51 PM Re: Help, what have I done !! EP500 has a rattle. [Re: SirQuack]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 4700
Randy,

It's on my Denon so I'm sure it's on yours.

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#177090 - 09/21/07 05:18 PM Re: Help, what have I done !! EP500 has a rattle. [Re: Murph]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 4700
Murph,

As I mentioned before, I always leave that DTS setting alone. The only one that I sometimes change is Cinema Compensation. This adjusts the treble. (Most?) movies are recorded with a treble emphasis to compensate for high frequency attenuation due to the movie screen. If the treble in a movie sounds too harsh, I enable this and voila...perfect treble.

But let's get to your issue. My 600 is certainly not infallible (sorry Axiom). No sub is. But the only way I've discovered its vulnerability is by pumping very low frequency (below 22Hz in my case) pure tones at high SPL levels (over 100dB). With these pure tones and levels, I can definitely hear distortion similar to what your describe. Rattling is perhaps a harsh term to describe what I hear. Port noise, chuffing and a "tick-tick-tick" sound is a better description. But I have never been able to detect this during music and movie listening even when I turn it up stupidly loud.

Regarding the fluctuating dB levels, do you have your meter set to slow? When I set mine to slow, I don't have that problem but with fast I certainly do.

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#177091 - 10/03/07 03:05 PM Re: Help, what have I done !! EP500 has a rattle. [Re: Mojo]
Murph Offline
axiomite

Registered: 10/05/06
Posts: 6955
Loc: PEI, Canada
Hi all,
Was traveling last week so I didn't think to post a follow up. The culprit was indeed the DTS setting in my Denon. Actually, it was the user's neglect in rechecking that setting after playing around with it, to be more honest.

It was set to 0 instead of -10. Because of this, I had turned up my sub to compensate, beyond what I used to have it at. When I played a DTS movie or certain music, like NiN, it was causing it to run a bit hot and 'distorting' the bass for lack of knowing what word best describes what I heard. I always tend to choose DTS when available so I didn't catch on. It wasn't as present in Dolby stuff. (I guess some DTS is truly louder bass wise)

I set the DTS setting back to -10 and I still felt the bass was a bit overwhelming (dial still high) but the rattle was gone. I turned the dial back to the pen mark at around 7:30 where I originally thought it sounded best and I was back to musical bliss.

In fact, the bass is actually more intense now. When it was rattling, you couldn't really feel the bass like you used to. Now I'm hearing and feeling it nicely again.

Thanks for your contributions! It turned on my light bulb, so to speak. I said it before and I'll say it again. Best product Web Board EVER!!
_________________________
With great power comes Awesome irresponsibility.

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#177092 - 10/03/07 03:21 PM Re: Help, what have I done !! EP500 has a rattle. [Re: Murph]
Murph Offline
axiomite

Registered: 10/05/06
Posts: 6955
Loc: PEI, Canada
I forgot to add...
The meter is no longer wavering when I try to get a db reading. I must assume that it was so working so distortedly hard (OK thats not a real word) that it couldn't even produce a consistent SPL level.

Could 10db and a notch or two on the dial push my poor 500 to this level of stress? Dunno, but I hope I didn't damage it. Sounds great again but wow, was I scared for a while.
_________________________
With great power comes Awesome irresponsibility.

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#177093 - 10/03/07 04:22 PM Re: Help, what have I done !! EP500 has a rattle. [Re: Murph]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 4700
Quote:

It was set to 0 instead of -10. Because of this, I had turned up my sub to compensate, beyond what I used to have it at.




0 is actually louder than -10.

If it's built like my 600, I really don't believe you've damaged it in any way. It's designed to throttle back no matter what you throw at it. But even throttled back, when pushed to ridiculous SPLs, it will distort, it will chuff, the grill and the top of the cabinet will resonate.

What I've found most objectionable from my 600 was resonance from the cabinet top and the grill when pushed to ridiculous SPLs. 95% of the time I don't push the 600 because the SPL is too high for me and other listeners. So I put a folded towel on the top and then my beaver on top of that for those crazy moments. And if I'm gonna watch a movie with tons of special effects at ridiculous SPLs, I take the grill off. Problem solved. The port noise and distortion is only noticeable when I play a 22hz or less test tone. And I'm usually not in the mood for test tones very often .

I am constantly amazed at how well this sub peforms with both movies and music. It's incredibly smooth and transparent. I feel Axiom has balanced SPL and product limits very well. Most listeners wouldn't even pick up on these potential areas of improvement at the extreme operating limits of the product. I often wonder though how this sub would sound if it contained more polyfill. I've been meaning to try that but have never gotten around to it. If anyone at Axiom has experimented with this and can describe the effects to me, it may end up saving me a lot of time.

So maybe you need to buy yourself a nice beaver like mine.



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#177094 - 10/03/07 05:09 PM Re: Help, what have I done !! EP500 has a rattle. [Re: Mojo]
alan Offline

connoisseur

Registered: 01/29/02
Posts: 3261
Loc: Toronto/New York/parry Sound
Mojo,

My, what a handsome beaver! (Only Canadians could exchange pleasantries like this without getting a lot of guffaws. .).

I once had a family of real beavers that constructed a house under a floating dock I'd built at a summer cottage.

Regards,
_________________________
Alan Lofft,
Axiom Resident Expert (Retired)

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