SDA SRS drivers popping at high volume

joeparaski

Huh? What do you mean what happened to that t.v.? What's wrong with it?

heiney9

joeparaski wrote:

Huh? What do you mean what happened to that t.v.? What's wrong with it?

I think Noel was referring to the streaks and shadows in the photo. At first glance it looks like the TV screen is damaged in the left corner.

H9

joeparaski

Oh...well the t.v. is perfectly fine and it better stay that way because getting it downstairs required 4 guys and lots of cursing. If and when it dies it will get the chainsaw treatment for removal from the basement.

vikashp

Haven't been here for a while but been a polkie since 1988 when I bought a new pair of SDA 1C's. I have also noticed this popping sound on multiple woofers on both the SDA 1C and SRS 2.3. I have never heard this from any speaker and I thought upgrading to the 2.3 would make the problem go away. This occured with an older Denon 110x2 and also my current Acurus 200x3 amp.

It happens with any material that is loud and lots of bass. For testing purposes I've even tried a Dolby Digital Test Tone DVD. Using low frequency tones I can slowly turn up the volume and watch the woofers moving back and forth. When I get to a certain point you hear a fluttering noise. Then if you turn it up a bit more it's as if the woofers are over extending or the voice coil is hitting the back. It's definately a mechanical noise like a snapping or popping. I'm so surprised other people haven't heard it before.

F1nut

I've never had that happen to any of my SDA's. At what volume level does this occur? Are you running any tone controls flat?

danger boy

F1nut wrote:

I've never had that happen to any of my SDA's. At what volume level does this occur? Are you running any tone controls flat?

+1
how does that happen? I've been on here a lot of years.. untill these past weeks/months had never read anything like this before.

Some times i'll put in a heavy bass CD.. to show off to friends how low they can go. still with a bass mastered CD, none of my drivers pop. So i'm confused how you guys have had yours pop some times

heiney9

vikashp wrote:

Haven't been here for a while but been a polkie since 1988 when I bought a new pair of SDA 1C's. I have also noticed this popping sound on multiple woofers on both the SDA 1C and SRS 2.3. I have never heard this from any speaker and I thought upgrading to the 2.3 would make the problem go away. This occured with an older Denon 110x2 and also my current Acurus 200x3 amp.

It happens with any material that is loud and lots of bass. For testing purposes I've even tried a Dolby Digital Test Tone DVD. Using low frequency tones I can slowly turn up the volume and watch the woofers moving back and forth. When I get to a certain point you hear a fluttering noise. Then if you turn it up a bit more it's as if the woofers are over extending or the voice coil is hitting the back. It's definately a mechanical noise like a snapping or popping. I'm so surprised other people haven't heard it before.

The problem comes in when you are underpowering the speakers or are trying to produce a really low bass note at higher volume or when you have loudness switch on at higher volumes or bass boosted. Like I said before I ran into this alot when I sold them. It happened on all models and was usually younger kids trying to play Ac/Dc, etc. at ear bleeding levels with out having enough power.

You can usually get away with a mild pop a couple times but in these cases it sounds like the damage was done. It's a blown driver(s) plain and simple. A driver doesn't have to completely cease functioning in for it order to be blown. I'm not sure the best way to isolate the driver, obviously you don't want to turn it up so loud to reproduce the sound. Perhaps there are some measurements you can make across the drivers to see which one it is. Call Ken @ Polk CS and see if he has any suggestions for isolating the bad driver.

Your Acurus probably puts out enough power now, but the Denon may have caused the problem to begin with and once the damage is done there is no going back.

BobMcG

heiney9 wrote:

The problem comes in when you are underpowering the speakers or are trying to produce a really low bass note at higher volume or when you have loudness switch on at higher volumes or bass boosted.

I agree to a point. The point about "or are trying to produce a really low bass note at higher volume". You've listed what are probably the most common reasons for driver failure. However, I think that some of the mid-woofers Polk made just couldn't take all that they were supposed to take.

The amp I was using on the 2Bs when they developed a problem is not underpowered for the job.

There were no processors in the signal path such as tone controls, loudness buttons, bass boosters etc. They didn't even exist in the system.

The original drivers had no problem handling any recordings at any level I used up until the first time I used this particular (then new) recording. It was with one particular bass note (not an extremely low note but a powerful note.) I first experienced the popping noise.

The original drivers weren't being driven at an unusual level at the time the problem occurred.

The replacement drivers handled the same recording and level without a hitch.

The same amp drove the 2.3s when I first got them and they handled the same recording and level without a problem. (The 2.3s have never had this issue to this day.)

Just an extra thought on why this might occur.:)

heiney9

^good point to keep in mind.

joeparaski

I'm certainly glad to hear the I'm not the only one that experienced the popping. However, it's dissapointing to know that it "may" be bad driver/s.

I have a chance to buy an abosolutely MINT set of 1.2 tl's....but....I've tapped out my "speaker fund" and I'd have to sell my SRS to help pay to the 1.2tl's.

reeltrouble1

Yes Bob I hear you. Didnt this other fellow state he was turning up the volume a little at a time until he actually hard clipped the driver, not a transient hit. Sounds like the typical underpowered scenario.

RT1

joeparaski

reeltrouble1 wrote:

Yes Bob I hear you. Didnt this other fellow state he was turning up the volume a little at a time until he actually hard clipped the driver, not a transient hit. Sounds like the typical underpowered scenario.

RT1

I wouldn't be too sure about the unpowered scenario....I run them bi-amped with the low amp delivering 350 wpc rms at 8 ohms and the highs amp at 200 wpc at 8 ohms and still get the pop at high levels.

reeltrouble1

I am sure Joe. But not your post that other fellow vika. You are attentuating (big word huh!) at least I think thats the word, various signals with all your EQ's.

RT1

vikashp

I figured instead of explaining the sound it might be better to let you listen and see for yourself. I made a small video clip where I turn up the volume gradually and the popping sound gets worse. Bear in mind that this is pretty loud and I started the video right when the drivers start making wierd noises so I'm really pushing them. The audio might sound a little scratchy since my cam is so close to the bass but if you can filter that out you can here the popping. Also I'm not sure how this will sound on your pc speakers. I couldn't find my Dolby demo disk so I used a bass music cd.

This same problem occured on my new SDA 1C's and these 2.3's so I'm not sure if it's bad woofers or the design of the woofers.

Hey Joe. Is this what you are talking about?

http://www.hollowlake.com/vik/polkspeakers.wmv

Vik

reeltrouble1

Holy crap!! Well I cant tell for sure what that is, it almost fits the music. You are talking about that sort of low waffling sound, that occurs ever few seconds as is regular in its "tone"? Or is that part of the recording? Maybe I just cant hear it.

RT1

vikashp

When the volume is turned down a few db's instead of hearing that flutter/popping noise you hear a very smooth long bass note. It's very clean and more of an airy vibration than a sound.

I'll try to find my Dolby demo disk and use a continuous bass tone so it's easier to hear the sound degrade.

Vik

reeltrouble1

Well the audio clip does not sound like a "hard clip" to me. Yet in your first post in this thread as you drove the driver harder and it had that "mechanical" sound that sounds like hard clipping. That acurus should run your speaks pretty well, if its working properly. How loud (spl) are they playing when the noises happen?

RT1

Loud & Clear

He's talking about the sound that sounds like you put your hand in the way of plastic fan blades, or if someone were demonstrating some low frequency wind-passing skills.

reeltrouble1

exactly, ok, it sounds like a well timbered ****. When he turns it down a bit it goes away. Maybe the "prior" damage theory, but it sounds like a blown driver on the snipit. They all do this? Or can you tell, you could remove them and replace one at a time to see.


RT1

vikashp

Ok. Here is another clip with Pink Floyd's Dark Side of the Moon cd. This is the heart beat sound which hopefully many of you will recognize as a smooth bass note. In this clip I alternate between low volume and high volume a few times to show the popping noise before and after.

http://www.hollowlake.com/vik/pinkfloydpolkaudio.wmv

Vik

heiney9

Guys....it's one of two things as mentioned.

1. Bad drivers, for whatever reason. Prior damage or old age.

2. Over driving the mid-bass drivers with either to low a frequency and not enough power or using too much processing and loudness or just plain clipping the low signal. When it starts to flutter (w/o poping) you've reached the excursion limit of the driver or the ability for the amp to control the driver(s). Regardless of how much power said amp produces.

This is really not that hard of a concept, only a few things can cause this. Watts are not watts and this is a prime example of there being what should be enough power but obviously there is some characteristic of said amps that causes the loss of control of the drivers.

The cabinet volume on the big SDA's is very large and throw the passive radiator into the mix which has to work off the cabinet volume and the pressure created by the mid-bass drivers and you can see why this is happening. PR designs not only need a fair amount of power they typically need an amp that can really control the drivers, there's a lot going on in that big cabinet. It's a matter of all these seperate issues accumulating to cause a problem. No offense to anyone's gear but it has it's limitations regardless of how much power it puts out. You can't look at one dimension and assume that just because the rated output is **** watts that it will perform well at it's limits.

I will also reiterate that if the driver has been damaged at one time, it will continue to pop until it's replaced. They don't magically reset or fix themseleves over time.

H9

danger boy

something is wrong with your SRS's. that don't sound good at all. is it happening to both speakers?

Get a SPL meter and see what db the volume is at. That's a good way for us to know if you're overdriving them or not. The drivers in mine have never made that noise. and don't move in and out that far either. What Pink FLoyd track was that?

joeparaski

vikashp wrote:

I figured instead of explaining the sound it might be better to let you listen and see for yourself. I made a small video clip where I turn up the volume gradually and the popping sound gets worse. Bear in mind that this is pretty loud and I started the video right when the drivers start making wierd noises so I'm really pushing them. The audio might sound a little scratchy since my cam is so close to the bass but if you can filter that out you can here the popping. Also I'm not sure how this will sound on your pc speakers. I couldn't find my Dolby demo disk so I used a bass music cd.

This same problem occured on my new SDA 1C's and these 2.3's so I'm not sure if it's bad woofers or the design of the woofers.

Hey Joe. Is this what you are talking about?

http://www.hollowlake.com/vik/polkspeakers.wmv

Vik

Hmmmm.......interesting. Mine isn't quite the same, it sounds deeper. Of course it may sound the same if listening to it live instead of through the internet. Maybe I'll try and record the same clip with my video camera.

danger boy

glad you provided the video clips.. because I wasn't quite understanding the popping sound that you were talking about. I definately hear it flutter and pop.

It seems that you may just be reaching the limits of those drivers.. and that's how they react.

Maybe i've never heard it because with the SRS's i have.. it's more drivers pumping out the sound. 8 mid drivers X 2 = 16 and i play some deep bass tracks in those too. but not very often.. the bass shakes the floor and you can really feel it. but they have never bottomed out or done that popping you guys are talking about.

*I played that heartbeat opening track from DSOTM, got out the SPL meter.. and measured it between 91 and 98 db. no popping heard here... but now i need to change my underwear. :eek:

heiney9

danger boy wrote:

glad you provided the video clips.. because I wasn't quite understanding the popping sound that you were talking about. I definately hear it flutter and pop.

It seems that you may just be reaching the limits of those drivers.. and that's how they react.

Maybe i've never heard it because with the SRS's i have.. it's more drivers pumping out the sound. 8 mid drivers X 2 = 16 and i play some deep bass tracks in those too. but not very often.. the bass shakes the floor and you can really feel it. but they have never bottomed out or done that popping you guys are talking about.

*I played that heartbeat opening track from DSOTM, got out the SPL meter.. and measured it between 91 and 98 db. no popping heard here... but now i need to change my underwear. :eek:

This is why I believe they are just running out of juice and the amp(s) can't control the drivers the way they should at the amp(s) limits. You can have sufficent power but at the limits with certain material on certain speakers the amp just falls apart. Raw wattage is just one small facet of amp design.

H9

danger boy

H9, so are you saying in some instances the amp is out of headroom?

heiney9

danger boy wrote:

H9, so are you saying in some instances the amp is out of headroom?

Yes, that's one possiblity. I guess what I'm trying to get across without going into massive detail is all amplifiers handle the load differently. The thing we tend to forget is by connecting the amp to the speakers it's a circular loop so to speak. It's not like the signal is dead-ending into the speaker teminals. The amp is receiving a feedback (for lack of a better word) of part of the signal and responding. Eveything is one big electrical circuit. One other thing is we don't typically think of the SDA's as being a particularly difficult speaker to drive. But, there is lots of cabinet volume and with the PR the control of all the drivers is an issue. It's not just a matter of impedence.

Amplifiers respond to the load the speakers provide which is infinetly changing based on the amplitude and frequency of the signal being fed to them. There will always be instances where an amp will fail to perform, usually when it reaches whatever the limiting fator is. In this case it MAY BE that a particular low bass signal fed from said amp to the SDA's test the ability of the amp to produce a clean signal. It may only occur with certain material at a certain volume level, but at other times performs just fine. This is all independent of wattage ratings.

This is one of the reasons there are notable differences between the likes of Krell, Bryston, Parasound, Outlaw, Adcom, Audio Source, etc. When you start pushing things to their limits, some will respond nicely and others may not. Electricity doesn't behave in conventional ways that are always predictable. I can only assume since this isn't an epidemic that it has to be equipment related. And just stating you have **** amount of watts doesn't mean you can push them to an infinite level of loudness.

I've heard a 60 watt amp play as loud as 200 watt amp with very difficult speakers. The 200 watt amp could reach a higher output, but not cleanly it was moderately clipping.

Well I've rambled on..I hope it made some sense.

H9

reeltrouble1

heiney9 wrote:

Well I've rambled on...

H9

ya think!!!!!!;) :eek: :rolleyes:

Vika, I would stop doing that to the drivers.

RT1

reeltrouble1

We could talk about this endlessly, the drivers sound bad, Vika I would call Ken Swauger at Polk CS and talk to him, sometimes he is kinda busy. Get the specs for Acuras you are using.

RT1

heiney9

reeltrouble1 wrote:

ya think!!!!!!;) :eek: :rolleyes:

Vika, I would stop doing that to the drivers.

RT1

Ted, come on now there was some useful information in my post. Ditto on the driver situation.....just stop it.

H9