[doggie]

I have a great pair of Omega Super 6 Alnico floorstanders with some updated drivers.Today I was playing a version of “Pictures at an Exhibition” which has deep organ tones. Unhappily I found that on the really low notes the whizzer cone on one speaker started making what I would call “unwanted sympathetic vibration” which was easily heard at my seat. It was a buzz or rattle. I use the speakers full range and am using the provided "nerf ball" plugs in the bottom firing ports.

The music was playing at what I consider a realistic volume in a modest sized room but not “head banger” territory. Is this a limitation of the single driver speaker being unable to really deal with deep bass or a problem with this driver? I did not hear this coming from the other right side driver which often gets more low note responsibility with classical orchestra music. On music without really deep bass I do not hear the problem or else it is not bad enough to draw attention at the listening position.

Any ideas?

Thanks!

Paul

[RDavidson]

Well.......I think what you're finding is simply that Omegas aren't "full range" speakers. The term "Full range single driver" is a bit of a misnomer. Even big multi-way speakers often fail at playing organ tones without some form of distortion. Really, it's pretty impressive what your Omegas are doing without distorting worse. My guess is that you're merely playing your Omegas at their limits....which is a compromise all single driver speakers suffer to some extent.

Or maybe I'm misunderstanding you and your Omegas never distorted this way before with this music, but now they do? A quick test to see if it's a driver issue or if it's merely the music  signal (exciting the distortion) is to just switch your speaker cables around and see if the other speaker acts the same.

[pstrisik]

Paul,

I've the original Super 7 XRS with alnico driver, so not too different.  I ran them full range until recently implementing an active, line level crossover.  I don't use the nerf ball.  I've never heard what you describing.  I'm not a head banger either, but I have had them up pretty loud. 

Is it only during that song?  Some ELP goes unusually low and atypically loud for that frequency.  Or are you hearing it with a number of songs?  Led Zeppelin maybe?

Might try running the bass tone files and see if any particular frequency is the culprit.  Will likely help diagnose anyway.  Might be helpful if you talk to Louis about it. 

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


.....Peter

[DaveC113]

The driver may be damaged... call Louis and explain, I'm sure he'll take care of you.

[vinagunner]

v

[Canada Rob]

Personally I'm not big fan of the Nerf ball plug as it will put more strain on the glue joint holding the whizzer cone onto the voice coil bobbin due to higher internal pressure, especially with heavy bass.  You may have loosened the whizzer cone attachment to the voice coil bobbin.  I know the Hoyt Bedford speakers had the Nerf ball option but was unaware the Alnico XRS came with Nerf balls.  When I had the Hoyts, I tried plugging the ports with the included Nerf balls and immediately unplugged them as I didn't care for the sound.  If bass booms too much I would, if possible, pull the speakers out further from the wall and leave the ports unplugged.

[FullRangeMan]

The music was playing at what I consider a realistic volume in a modest sized room but not “head banger” territory.

Seems you exceed the power handlig limit of the driver.
You would listen at lower SPL to preserve driver.

[doggie]

You are right. Louis has always been extremely service oriented. I bought these speakers used a couple of years ago via Agon. When they arrived one driver had suffered from shipping. Even though they were not under the original warranty Louis sold me replacement drivers at his cost.

I think that I will try reversing the cables, pulling the nerf balls, and using my ancient Stereophile test CD to gather more information and then give Louis a call today. I have a good sub but that does not relieve the Omega drivers from trying to follow it down there! I guess that organ music can realistically be considered a torture test for speakers that excel at delicacy.

Thanks for all of the good advice.

Best,

Paul

[doggie]

Personally I'm not big fan of the Nerf ball plug as it will put more strain on the glue joint holding the whizzer cone onto the voice coil bobbin due to higher internal pressure, especially with heavy bass.  You may have loosened the whizzer cone attachment to the voice coil bobbin.  I know the Hoyt Bedford speakers had the Nerf ball option but was unaware the Alnico XRS came with Nerf balls.  When I had the Hoyts, I tried plugging the ports with the included Nerf balls and immediately unplugged them as I didn't care for the sound.  If bass booms too much I would, if possible, pull the speakers out further from the wall and leave the ports unplugged.

Thanks. Mine are called "Super 6 Alnico Custom Shop" and I believe preceded the XRS. They have the down firing port but are not tilted back. In my setup I felt that the nerf balls kept them from going quite so low but made what was there tighter and clearer. Assuming the drivers are not actually damaged perhaps I should just remove the nerfs for the few organ pieces I play.

[DaveC113]

Personally I'm not big fan of the Nerf ball plug as it will put more strain on the glue joint holding the whizzer cone onto the voice coil bobbin due to higher internal pressure, especially with heavy bass.  You may have loosened the whizzer cone attachment to the voice coil bobbin.  I know the Hoyt Bedford speakers had the Nerf ball option but was unaware the Alnico XRS came with Nerf balls.  When I had the Hoyts, I tried plugging the ports with the included Nerf balls and immediately unplugged them as I didn't care for the sound.  If bass booms too much I would, if possible, pull the speakers out further from the wall and leave the ports unplugged.

I was going to mention this, Rob is absolutely right. Sealed boxes require far more cone excursion vs ported boxes, but if you're playing organ music at high volumes you'll be sending it signals below the tuning frequency when the port is un-blocked which can also be a problem as far as excessive excursion goes.

The solution is to high pass the speaker at a steep slope above the tuning frequency, I've been using 50 Hz and 24 dB/oct. Let the sub take care of the lows. But this setup isn't optimal for sound quality at lower volumes or music with less bass. About 95% of the time I'm happy with powering my Omegas full range with my low power SET amp, if I want volume I'll use the Crown with it's built-in crossover.

And RDavidson is right in that most systems are going to be straining to play this type of music. The heavy low frequency content should not be played through most normal speakers, it really needs to be played by a dedicated subwoofer that was designed to handle these frequencies, and that doesn't even include your average subwoofer, many are not up to the task. You need a serious subwoofer to handle this kind of music.

[Canada Rob]

Deleted and clarified further down.

[rebbi]

Doggie,
I want to echo what everyone else said about getting in touch with Louis. One of my new Super Alnico 6 monitors arrived with a buzzing/rattling noise that developed in one of the speakers. It was initially excited or aggravated by some low bass information, but it got worse and worse. It turns out that FedEx manhandled the box (or so we surmise) and knocked the voice coil out of alignment. If you looked carefully, you could even see on very close inspection that the whizzer cone was slightly off center, i.e., not entirely perpendicular to the main speaker cone. So again, definitely, speak with him and he will tell you what he thinks is going on.

[doggie]

Doggie,
I want to echo what everyone else said about getting in touch with Louis. One of my new Super Alnico 6 monitors arrived with a buzzing/rattling noise that developed in one of the speakers. It was initially excited or aggravated by some low bass information, but it got worse and worse. It turns out that FedEx manhandled the box (or so we surmise) and knocked the voice coil out of alignment. If you looked carefully, you could even see on very close inspection that the whizzer cone was slightly off center, i.e., not entirely perpendicular to the main speaker cone. So again, definitely, speak with him and he will tell you what he thinks is going on.

Doggie,

There is no music "type" (organ included) that will damage your speakers.  You can play deep organ on a pair of micro monitors if you want - the speaker just won't play those low notes because it won't go down that low.  Where the damage comes in is if your amp isn't up to the task and it goes into clipping whether not powerful enough or turned up too high - that can damage or cook your voice coils.  The Nerf plug problem that I mentioned in an earlier post is a completely different issue and I'm not contradicting myself in this post.

Best to talk to Louis.

Thanks Rebbi. I contacted Louis and he felt that the whizzer just needs to be re-glued. As usual he was very responsive.

Rob. Thanks for the comment about low bass. It had not been an issue previously with the same piece of music so that supports what both you and Louis mentioned.

Regarding the nerfs. On these speakers and in my system the difference in sound quality with them in place is not subtle. Everything is much clearer and tighter and dynamic with them in place.

Best,

Paul

[DaveC113]

Rob, if you exceed the designed excursion limits it's very possible to damage a driver. Music containing low frequency information produces more excursion, for example organ music. With ported boxes, it's very easy to damage drivers by playing music containing information below the tuning frequency of the box.

[RDavidson]

Yup. Not exactly an apples to apples comparison, but try playing low (unclipped) bass tones through a dome tweeter without a crossover to protect it. Won't take long to fry it, even at low output, regardless of how well engineered it is.

[Canada Rob]

Rob, if you exceed the designed excursion limits it's very possible to damage a driver. Music containing low frequency information produces more excursion, for example organ music. With ported boxes, it's very easy to damage drivers by playing music containing information below the tuning frequency of the box.

Totally true, and especially in a vented or open baffle cabinet where there is less or no dampening air cushion as in a sealed box.

However, in the real world people play all kinds of music on all kinds of speakers for the most part without any issues at all.  A speaker that's rated at 50-20,000Hz will have movement on signals below 50Hz, but in most cases not enough to cause over excursion.  If our speakers are going to be damaged by signals outside their rating we would have to be almost paranoid about what music we choose for our systems and that's neither fun nor practical.  The sure fire way to keep from damaging our drivers is to leave the stereo turned off.

[RDavidson]

Totally true, and especially in a vented or open baffle cabinet where there is less or no dampening air cushion as in a sealed box.

However, in the real world people play all kinds of music on all kinds of speakers for the most part without any issues at all.  A speaker that's rated at 50-20,000Hz will have movement on signals below 50Hz, but in most cases not enough to cause over excursion.  If our speakers are going to be damaged by signals outside their rating we would have to be almost paranoid about what music we choose for our systems and that's neither fun nor practical.  The sure fire way to keep from damaging our drivers is to leave the stereo turned off.

Let's not get carried away.
Obviously we're not only talking about just low frequencies, but also volume / power. Without a crossover, the driver will "see" and attempt to play whatever signal it is given. Give a driver a full range signal (see my tweeter example) and it will attempt to play it regardless of its ability to do so.
To your point, actually everyone is at risk of blowing their speakers to some extent, but most of us listen at reasonable levels, ie levels that won't get anywhere near damaging our drivers. With that said, there will always be some extreme cases. I think the OP's case may be an example of such.

[DaveC113]

Rob, I agree it's usually not an issue, I've seriously abused my RS5 drivers...     They seem very durable, I've never had an issue with them, but any driver has it's limits. Attempting to play organ music at anywhere approaching realistic volumes on ANY single driver speaker is going to tear it apart, but this is true with most any speaker. Even dedicated subwoofers struggle with music like that.


FWIW... the first indication you're going to far is obvious IMD, where the excessive excursion interferes with the mids and highs. If you hear this turn it down!

[doggie]

Just to close the loop on this...

Louis sent me a new driver.

It would be hard to overestimate how great the service is with Louis.

[rebbi]

It would be hard to overestimate how great the service is with Louis.

You said it.