Sierra 1 & bass distortion?

I am running on Onkyo 705 with 5 channels (no .1 and I probably do as much 2 channel as 5...). While watching The Dark Knight Rises Blu-ray, I noted a few instances where my front left Sierra 1 and to a lesser extent the right seemed to have a slight rattle (I was attributing it to additional "detail" in the background of the movie and not a rattle). The element that has me concerned however is when Fox takes Miranda on the elevator/platform down to the reactor and the elevator hits bottom/stops. A heavy bass signal is sent which made the speakers (and yes, it came from the speakers and not the room) --esp. the front left-- sound like a rattle was coming from them. This is the secondary concern however. The primary concern is that the speakers (left front in particular) created a sound with that base signal similar to what one would expect small speakers from a child's toy (or inexpensive external computer speakers) to create if hooked up to play one of the lower registers of a pipe organ or bass heavy rap etc.

Initially, I wondered if it was actually the sound editing, but playing it at a very quiet level seemed to resolve this. Volume was set at 70 (for those with familiarity-- I know, there can be a lot of variables). Suffice it to say that it was not exceptionally loud and the distortion could be replicated at about 63 up.

So the questions:

1) MOST IMPORTANTLY: Does any of this seem to suggest that my speaker may in fact be damaged OR may have suffered damage? I have never heard this from these speakers, but then I have never watched this disc until tonight. I would not expect moderate volumes from a reasonably powered receiver and outstanding speakers to do this.

2) What is anyone's guess as to what happened?

Thank you for knowledgeable insight.

Do you use a sub? The speakers are running fullrange?

Probably sent some pretty low frequencies at an output level that caused excessive port noise....or maybe bottom out the woofer(although I have never read that happening).

Curtis,

Thank you for the reply. I know a great deal about "listening" but considerably less about the technical elements of what the speakers are "doing"...

No ".1" signal. In other words, no subwoofer. Yes, the fronts are set to full range. There is no doubt that it was a VERY low frequency that was put out at that point. Again, although the volume was somewhat high it was nowhere close to being what most would consider especially loud (and I am only sitting about 8.5' back for this particular setup).

I've never heard of excessive port noise with the Sierra 1. What can you tell me about it? If the woofer was "bottomed out" would that cause damage? Again, I really did not have things set very loud.

I am thrilled with these speakers and am truly hoping there is nothing wrong with one (or both).

Anybody able to answer?:(:confused:

The excessive port noise would sound something like a "flutter", caused by more air/velocity than was it was designed for.

Yes, bottoming could hurt the driver, but if anything was damaged, you would hear it during normal use.

Well, when I worked on replicating the sound with the volume starting low and gradually increasing each play time I positioned my cheek and ear relatively close to the port to attempt to better hear what was happening. There was certainly a tremendous and very sudden rush of air out of the port (almost felt like a small fan but in a burst). I don't know how to really describe the distorted bass sound other than if you have used a pair of cheap/small ear-phone jack type speakers plugged into a computer playing back music with any significant bass at a moderate volume. Can port noise sound similar to clipping? I certainly hope that is not what I heard (and come to think of it, don't figure that between the Onkyo and the Sierra 1 in a conservative set up and moderate volume this would be the case).

I presume the damage from bottoming a driver would be something that would be readily apparent then-- yes/no? I would expect that the volume should need to be set quite high as well.?.? What type of sound/indicator would I expect to hear from such damage? I have not been able to sit and listen since then due to other demands, but the little I did, did not sound objectionable.

Thank you so very much Curtis for sharing your time and information and any extra answers you can provide regarding these questions/concerns.

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Originally Posted by 883

Well, when I worked on replicating the sound with the volume starting low and gradually increasing each play time I positioned my cheek and ear relatively close to the port to attempt to better hear what was happening. There was certainly a tremendous and very sudden rush of air out of the port (almost felt like a small fan but in a burst). I don't know how to really describe the distorted bass sound other than if you have used a pair of cheap/small ear-phone jack type speakers plugged into a computer playing back music with any significant bass at a moderate volume. Can port noise sound similar to clipping? I certainly hope that is not what I heard (and come to think of it, don't figure that between the Onkyo and the Sierra 1 in a conservative set up and moderate volume this would be the case).

I presume the damage from bottoming a driver would be something that would be readily apparent then-- yes/no? I would expect that the volume should need to be set quite high as well.?.? What type of sound/indicator would I expect to hear from such damage? I have not been able to sit and listen since then due to other demands, but the little I did, did not sound objectionable.

Thank you so very much Curtis for sharing your time and information and any extra answers you can provide regarding these questions/concerns.

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Some parts of movies can have very deep bass and when the actual frequencies are lower than the port tune of the speaker (which in the case of the Sierra-1 is ~40Hz), the woofer will become unloaded and can exhibit extreme excursion. Because of the extreme excursion, there will be a lot of air rushing in and out of the port tube.

I strongly doubt your woofer is damaged, if it were -- you would hear mechanical distress with all source material, not just this once section of a soundtrack. Be careful though, extreme excursion like this can indeed damage a woofer. To avoid this, try setting the speakers to "small" and setting a low (40-50Hz) crossover point if you don't plan on adding a subwoofer to cover such deep bass...

hope this helps!

Mr. Fabrikant,

Thank you. I watched Ocean's Eleven and once again heard the same thing (during the demolition of a casino) once again at a fairly conservative volume. The disconcerting element to me is that along with the distortion it sounds like a rattle from inside the speaker (which made me worry about "bottoming out"/damage) when it happens and it sounds like it is primarily only occurring with one speaker. I actually wanted to set the crossover at 50Hz, but because I do not have a subwoofer the Onkyo locks the fronts to "Large" or "Full" after an Audyssey calibration.

I listen to more music than I watch movies and most of the music is classical at primarily conservative/moderate volume. With the limited listening I have had the opportunity to do over the last little while, things have sounded as beautiful as usual...

Do you have any other thoughts on the matter Mr. Fabrikant (damage, things to watch for, etc.)?

Thank you again.

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Originally Posted by 883

Mr. Fabrikant,

Thank you. I watched Ocean's Eleven and once again heard the same thing (during the demolition of a casino) once again at a fairly conservative volume. The disconcerting element to me is that along with the distortion it sounds like a rattle from inside the speaker (which made me worry about "bottoming out"/damage) when it happens and it sounds like it is primarily only occurring with one speaker. I actually wanted to set the crossover at 50Hz, but because I do not have a subwoofer the Onkyo locks the fronts to "Large" or "Full" after an Audyssey calibration.

I listen to more music than I watch movies and most of the music is classical at primarily conservative/moderate volume. With the limited listening I have had the opportunity to do over the last little while, things have sounded as beautiful as usual...

Do you have any other thoughts on the matter Mr. Fabrikant (damage, things to watch for, etc.)?

Thank you again.

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What you are hearing is precisely as I described in my previous post. The soundtrack of the movie combined with your receiver is asking your Sierra-1 speaker to reproduce dynamic 20Hz bass. The Sierra-1 is not going to like it (nor will most speakers) To make matters worse, since you are using Audyssey and Audyssey has no idea what the capabilites of the speakers are, your receiver is going to try and equalize the speakers flat to 20Hz, thus considerably boosting low frequencies in order to achieve a flat full-range in-room response. This is a really, really bad idea and you will eventually damage your speaker and this type of damage is not covered under our warranty since your receiver is asking the speakers to perform well out of their specifications.

That said, you need to override Audyssey and use a 50Hz crossover and then re-run the auto-eq. Your receiver does not "know" whether you have a subwoofer connected so if you can not override the settings, I recommend that you set the subwoofer option to "yes" in the receiver and just set a low crossover point... This is one of the major drawbacks with auto-eq systems, if you set the speakers to full range, Audyssey will try to equalize them to a flat full range response and the Sierra-1 are not full range loudspeakers...

Hope this makes sense!

Very helpful.

You mentioned that I would hear "mechanical distress" with all sources if the woofer was damaged... If you are able to describe, what would this sound like and would it be significantly dependent on volume level and or frequencies (needing to be particularly low)?

I apologize if this is beleaguering the matter but I truly hope my lack of understanding with the Audyssey and speaker combination has not likely (esp. noticeably) shortened the life of or damaged my speakers. I kinda love them.

Thanks again.

Mr. Fabrikant,

If you get the opportunity will you please share with me (I, having shared another incident and the use of Audyssey) if you still believe that the woofer is undamaged and more about the mechanical distress I would hear if damaged? I have since been very afraid to push any significant bass through them, I have set crossover at 50Hz, and while listening to basic orchestral arrangements at moderate volume the speakers have sounded as impressive as ever. I've got my fingers crossed.

I will add my .02 on Audyssey.

My Marantz AVR with Audyssey MultEQ set my Sierra-1 NrT's to Large. It recognized my 12" Rythmik sub and set distance/level for it. It set the Bass setting to "Mix". Well, I thought setting the Sierra's to Large was fairly typical as they go pretty low in the bass. I left it as set by Audyssey to give it a chance. I thought it sounded OK, but did not knock me over. After looking up the bass "Mix" setting in the manual I discovered that although the sub was calibrated, it was not being fed any bass. All the bass was being sent to the Sierra's. HUH?? How crazy is that?! Of course I fixed the settings. Sierra's set as Small, 80Hz X-over, "Yes" for sub. Sounds much better now.

Never trust these auto setup systems. Manually tweak things so the system works correctly.

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Originally Posted by 883

Very helpful.

You mentioned that I would hear "mechanical distress" with all sources if the woofer was damaged... If you are able to describe, what would this sound like and would it be significantly dependent on volume level and or frequencies (needing to be particularly low)?

I apologize if this is beleaguering the matter but I truly hope my lack of understanding with the Audyssey and speaker combination has not likely (esp. noticeably) shortened the life of or damaged my speakers. I kinda love them.

Thanks again.

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Quote:

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Originally Posted by 883

Mr. Fabrikant,

If you get the opportunity will you please share with me (I, having shared another incident and the use of Audyssey) if you still believe that the woofer is undamaged and more about the mechanical distress I would hear if damaged? I have since been very afraid to push any significant bass through them, I have set crossover at 50Hz, and while listening to basic orchestral arrangements at moderate volume the speakers have sounded as impressive as ever. I've got my fingers crossed.

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Hi 883,

If the woofer is damaged, you will know it... In nearly all cases of a damaged woofer, the voice coil is damaged and will eventually short -- there will be no output out of the woofer at all and the speaker will sound horrible. The other possibility is that the voice coil develops a "rub" -- in which case the woofer cone and suspension will no longer move back and forth freely. In this case, the sound from the woofer will be heavily distorted at any volume level.

Honestly, since you have set a 50Hz crossover and the speakers sound great --- everything is fine, don't worry and just enjoy the system. The woofers in the Sierra-1 are quite durable.

Tale care!

Thanks for the thoughts Mag_Neato. Nice to know another person's experience with Audyssey and setting up.

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Originally Posted by davef

Hi 883,

If the woofer is damaged, you will know it... In nearly all cases of a damaged woofer, the voice coil is damaged and will eventually short -- there will be no output out of the woofer at all and the speaker will sound horrible. The other possibility is that the voice coil develops a "rub" -- in which case the woofer cone and suspension will no longer move back and forth freely. In this case, the sound from the woofer will be heavily distorted at any volume level.

Honestly, since you have set a 50Hz crossover and the speakers sound great --- everything is fine, don't worry and just enjoy the system. The woofers in the Sierra-1 are quite durable.

Tale care!

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Thank you VERY much for the reply and for beautiful speakers. Much appreciated. I will enjoy. I suppose I will add a subwoofer since I do use them for movies as well as the music. Although, a sub that will provide the quality of bass I expect from my Sierra 1 will probably not be an option for the time -- this could be a disappointing problem if I want to crank up Michael Murray playing Bach on the pipe organ -- but at least those lower registers will come through without me worrying about abusing the Sierras :-).

Best regards.

Quote:

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Originally Posted by 883

Thank you VERY much for the reply and for beautiful speakers. Much appreciated. I will enjoy. I suppose I will add a subwoofer since I do use them for movies as well as the music. Although, a sub that will provide the quality of bass I expect from my Sierra 1 will probably not be an option for the time -- this could be a disappointing problem if I want to crank up Michael Murray playing Bach on the pipe organ -- but at least those lower registers will come through without me worrying about abusing the Sierras :-).

Best regards.

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It is my sincere pleasure!

Yes, for your usage (especially Bach ;) ) I strongly encourage you to add a subwoofer to the system.

Thanks again!

Dave,

Can't the cross over be designed not to allow frequency content less than the designed minimum frequency?

Aravind

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Originally Posted by ats_phd

Can't the cross over be designed not to allow frequency content less than the designed minimum frequency?

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I'm not Dave...but here are my thoughts...

A couple of things...
Not everyone has this issue...in fact, The Dark Knight is known to have a lot of low frequency output. It isn't something you want to do and then end up hindering other material.

In a crossover, you don't want to have to add components if you don't have to. Less is more. :)

I'm not Dave either, but here are my two cents. :p

Generally speaking, crossovers are not "brick wall" filters. Instead, they are "roll off" filters that can be adjusted depending on the requirements. Here is an example:

A typical crossover slope between a subwoofer and a loudspeaker is 12 dB/octave (aka second order crossover). If the crossover centering frequency is 80 Hz, this means that the crossover starts attenuating (reducing) frequencies below 80 Hz to the loudspeakers. For 12 dB/octave, the output at 40 Hz will be 12 dB less than output at 80 Hz. Likewise, at 20 Hz, output will be another 12 dB less than at 40 Hz.

For crossovers inside of loudspeakers, the slopes are usually steeper for several reasons. If memory serves, the low-cut (high pass) filter on the Sierra-1 woofer is 24 dB/octave (aka fourth order crossover). This is MUCH steeper than a 12 dB/octave slope, so the low frequencies are reduced more quickly. Using the same example above, if the low-cut crossover was set to 80 Hz, the output at 40 Hz would be 24 dB less (instead of 12 dB less in the previous example). Here's a visual example of three common crossover slopes used today:

http://www.rane.com/n160fig5.gif

There is a first order, 6 dB/octave filter that isn't shown, but you can see that a 24 dB/octave is much steeper than the 12 or 18 dB/octave slopes. There is a lot more involved with crossovers, but hopefully this helps shed some light on the issue.

To bring this home, the Sierra-1 loudspeaker has an in-room response of -3 dB around 40 Hz, and has a 24 dB/octave low-cut/high-pass filter on the woofer. So at 20 Hz, the output is 24 dB less than at 40 Hz. 24 dB is a lot of attenuation. This is how Dave can control the low frequency output of the Sierra-1, but also shows why the Sierra-1 can still respond to significant low frequency content like what you experienced with The Dark Knight. I actually rewatched this film recently and noted how intense the low frequency content was, even at lower volumes. The woofer moves outward and inward in response to the electrical signal. At mid-range frequencies, it only moves a little bit. At bass frequencies, it moves much more. With extreme low frequencies, the inward/outward motion (excursion) can be so much that you can actually hear the woofer move along with the significant rush of air being pushed out and sucked in via the port (as Dave mentioned).

If you don't plan to use a subwoofer, my honest recommendation would be to keep the 50 Hz low-cut crossover on your Sierra-1s when watching movies. This will help prevent the issue you ran into and give you piece of mind. :)

Thanks Curtis and Jacob !.

It makes sense now.

Sorry, I misread and thought you were the original poster (883). The last part about the 50 Hz crossover applied to OP. :)

The recommendation stands, though, if you're running a similar setup as OP. There is so much technical detail in this field. I love it.


Take care!

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Originally Posted by ats_phd

Dave,

Can't the cross over be designed not to allow frequency content less than the designed minimum frequency?

Aravind

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There is an acoustic high pass filter in all loudspeakers based on the cabinet volume and type of "tuning". With a ported loudspeaker, the bass response of the speaker rolls off very quickly below the port tune frequency (24dB/octave). However, this is not an electrical filter, meaning that the full range signal will still reach the woofer and the woofer will make an attempt at reproducing them.

Adding a passive electrical high pass filter for the low frequency woofer is just not done in a loudspeaker design. First off, this would require a capacitor in series with the woofer with a value of approximately 470uF, which is extremely large and I don't believe even available. Instead we would essentially have to use (2) 200uF caps and one 100uF cap all in parallel. For metalized polypropylene caps, I would estimate the total cost of just these caps to be around $180. We would then also require a 17mH inductor in parallel with the woofer, this also would be a huge component and I would estimate the cost of this to be around $80 for an air-core inductor. We would essentially be adding $500 in manufacturing costs to each pair of Sierra-1 (estimated retail price increase of $800) This new filter, while beneficial to reduce low frequencies below port tune, would also produce large phase shifts and serious impedance issues, literally destroying the overall performance of the woofer.

Loudspeakers are like a car, any car can be driven well past its potential with regard to speed and handling and thus risk serious mechanical issues. It is up to the user to use the device properly.

Hope this makes sense :)