Old AR2ax woofer distortion

[Seabert]

I just finished partial restoration of one of my AR2ax speakers which included installation of a new 10" woofer I bough from Ebay. The speakers came with non-AR woofers made in Taiwan, which is why I bough the new woofer. My first impression of the speaker with the new woofer and caps was very gratifying when listening to simple acoustic music such as Willy, Cash, Dylan, etc. However, when I started to really test the speaker with more complex recordings I notice that the woofer was having a very hard time keeping up with the tunes - very poor mid bass dynamics. Was worse is that in addition to the poor dynamics the woofer distorted at mid volume levels with pieces containing deep bass passages such as the Trinity Sessions. Is this normal? I tested the speakers with a well tuned Cary SLI80 Tube Amp in UL mode which delivers 80 Watts/channel so I am pretty sure that the distortion is not coming from the amp.

[Mexicomike]

What you describe is not normal for an AR2ax - I had a pair for years. From your description, I would suggest (in this order) that the "acoustic suspension" is not present, either due to an actual air leak in the cabinet or the woofer surround; there is insufficient fiberglass damping in the cabinet; the woofer itself is not correct or faulty (if re-foamed, is the cone centered so it isn't rubbing on the coil?). I assume that any crossover changes maintained the original specs so that the woofer isn't getting frequencies that it shouldn't be...

[Seabert]

What you describe is not normal for an AR2ax - I had a pair for years. From your description, I would suggest (in this order) that the "acoustic suspension" is not present, either due to an actual air leak in the cabinet or the woofer surround; there is insufficient fiberglass damping in the cabinet; the woofer itself is not correct or faulty (if re-foamed, is the cone centered so it isn't rubbing on the coil?). I assume that any crossover changes maintained the original specs so that the woofer isn't getting frequencies that it shouldn't be...

I did more testing last night and I need to clarify that to make the woofer distort I do have to crank the volume up a bit to about 12 o'clock and that it only distorts when playing music with deep mid bass passages. Try playing Ben Harper Oppression very loud. I resealed the cabinet with Mortile (rope caulk) because I could not find anything else at Home Depo. This is a hard caulk which I did not like and plan to replace as soon as I find the 3M caulking strips which I may just have to order online. So yes, it is possible that I do not have a perfect seal. Due to the hardness of the rope caulk I had to tighten the screw quiet hard which doesn't seem right either. However, I was very careful thought out the entire process and I doubt that all of the above is the cause of what I am experiencing. My feeling is that I either have a bad woofer or that these speakers simply have a limit as far as their ability to reproduce deep passages at very high volumes. I am also wondering if the distortion could be a result of bad room acoustics? My listening room is pretty small but my guess is that that would result in boomy bass not distortion. One thing I noticed which is interesting is that the woofer hardly moves at all when I played with the Cary, but if i used my HK630 the woofer starts to dance at high volumes. I need to confirm this observation. Do you know why?

[genek]

How does this relate to your other post about stuffing? Did you stuff the cabinet using either of the options you asked about in that post?

[Mexicomike]

The sealant that is best and is what AR used is called "Duct Seal" Here's an example: http://electrical.hardwarestore.com/14-46-...eal-176552.aspx You can get it at just about any hardware store, certainly at any Lowes or Home depot.

Re the cabinet seal - with no signal, press the woofer cone in a bit with your hand and quickly release it. If it springs back fairly quickly, the cabinet is not sealed. If it moves back relatively slowly - maybe 1/2 second or so - it's probably ok.

The 2Ax's will distort if turned up loud enough - I blew out midranges in them twice. Both were replaced for free, including shipping by AR and probably caused by my underpowered (40WPC) amp at the time. But the woofers will not be the problem. From the woofer excursions (dancing), it is clear that one of the amps is passing some low freq that the other is not. In the old (turntable) days, some preamps had an infrasonic filter that would block freqs below 20Hz to avoid unnecessary woofer excursion/amp power wastage that was caused by record warpage, etc. Maybe the Cary has that or some built-in circuitry to provide that? Of course, there could be some sort of stability issue with the HK, I suppose, causing the generation of some spurious low freq spikes.

80WPC for AR speakers is OK at moderate levels but at higher volume and challenging material you could be into clipping pretty easily, especially with substantial bass content. You might just be experiencing clipping. Be aware that clipping can rapidly destroy tweeters.

[Seabert]

The sealant that is best and is what AR used is called "Duct Seal" Here's an example: http://electrical.hardwarestore.com/14-46-...eal-176552.aspx You can get it at just about any hardware store, certainly at any Lowes or Home depot.

Re the cabinet seal - with no signal, press the woofer cone in a bit with your hand and quickly release it. If it springs back fairly quickly, the cabinet is not sealed. If it moves back relatively slowly - maybe 1/2 second or so - it's probably ok.

The 2Ax's will distort if turned up loud enough - I blew out midranges in them twice. Both were replaced for free, including shipping by AR and probably caused by my underpowered (40WPC) amp at the time. But the woofers will not be the problem. From the woofer excursions (dancing), it is clear that one of the amps is passing some low freq that the other is not. In the old (turntable) days, some preamps had an infrasonic filter that would block freqs below 20Hz to avoid unnecessary woofer excursion/amp power wastage that was caused by record warpage, etc. Maybe the Cary has that or some built-in circuitry to provide that? Of course, there could be some sort of stability issue with the HK, I suppose, causing the generation of some spurious low freq spikes.

80WPC for AR speakers is OK at moderate levels but at higher volume and challenging material you could be into clipping pretty easily, especially with substantial bass content. You might just be experiencing clipping. Be aware that clipping can rapidly destroy tweeters.

I listen to the woofer more carefully while playing Ani difranco back to back. The woofer was very stable to 11 o'clock but was challenged at 12 o'clock. In addition to the distortion I clearly heard a distinct rattle/vibration noise - like the noise you make when you run a piece of cardboard run through the spokes of a bicycle wheel. I lower the volume immediately. It is good to know that other speakers will distort if played loud enough because it gives me some hope that the woofer maybe OK. My worry is that the voice coil may be partially separated from the spider. Is there an easy way to actually look for damage without taking the woofer apart.

I will try resealing the cabinet with the proper caulk to see if that makes a difference. I will also weight the fiberglass.

Is clipping induced by poor electronics in the speaker? The Cary has been driving my EPOS M22s which are very hard to drive and it has never shown any sings of distortion even with the volume almost all the way up. At that level you can feel the air from the woofers in the EPOS in the entire room.

[genek]

Is clipping induced by poor electronics in the speaker?

No. Clipping happens when you turn the amplifier up high enough to exceed its limits on peaks. The only way a speaker influences this is by requiring more power than the amplifier is capable of producing cleanly.

[ADVENTAGIOUS]

No. Clipping happens when you turn the amplifier up high enough to exceed its limits on peaks. The only way a speaker influences this is by requiring more power than the amplifier is capable of producing cleanly.

Do these AR's have cloth surrounds?

[dynaco_dan]

The sealant that is best and is what AR used is called "Duct Seal" Here's an example: http://electrical.hardwarestore.com/14-46-...eal-176552.aspx You can get it at just about any hardware store, certainly at any Lowes or Home depot.

, especially with substantial bass content. You might just be experiencing clipping. Be aware that clipping can rapidly destroy tweeters.

Hi there

You are incorrect regarding the duct seal.

I have sugested several times to use the compound as it is cheap, pliable and certainly more than adequate for the job.

I had worked at an AR warantee depot long ago and the 3M product is as close as darn today as to the original material used.

I suspect that we will never know the exact composition of the original compound as it may have contained asbestoes or other haszardous material by today's standard.

I went out and purchased a box of current production equivalent and it is very close without getting an anaylysis.

Not wanting to start a heated discusson but just passing on my experiences.