The Official Premier Acoustics Owners thread

[aramis109]

Yeah, waiting sucks but the black looks really nice. And no, I have not (nor will I) add any polyfill on this one. I think it has enough by default and it sounds great.

[Aerodude73]

Originally Posted by aramis109

Yeah, waiting sucks but the black looks really nice. And no, I have not (nor will I) add any polyfill on this one. I think it has enough by default and it sounds great.

Good to know!

[duneaholic]

I took the front grill off(PITA) but it does come off. I took the driver off and filled my with poly. I didn't notice a huge difference but I did notice it. This sub is really well built. Nice bracing on the inside. The amp looks high quality too. Isn't the PA amp based on the Bash amp?

[Yeha-Noha]

Originally Posted by aramis109

And no, I have not (nor will I) add any polyfill on this one. I think it has enough by default and it sounds great.

+1 Aramis109, that's a wise decision.

I can justify adding polyfil to a closed box which can extend the bass response if done properly by lowering the Qt for a box that is smaller than required for a specific driver by making the box effectively larger than its physical size, ie by volumetric expansion. That's good as long it achieves a Qt = 0.7 to 1.0. A Qt lower than that (say 0.5) will end up overdamping the driver especially if the driver's Qts is already low (0.3 to 0.4), and you will end up bottoming out the subwoofer possibly damaging it. Drivers with such low Qts are better suited to ported designs.

It's a bit different for ported designs though. Adding polyfil to a ported box is tricky because the box is tuned to a specific frequency (fb). I would only add polyfil to a ported design for the purpose of fine tuning it to the correct frequency required by that design for that particular driver. Adding too much or too little polyfil will alter the calculated box volume. If you alter the box volume, you change the tuning. Thus if you don't know the box tuning frequency, then how do you know how much polyfil to add? Trial and error, perhaps? Well maybe with enough patience. All I can say is, good luck to those who attempt it.

Now, the folks owning AA subs say that adding polyfil helps. Perhaps by chance or by coincidence it does. But what if AA HD sub designers who certainly know or should know what the driver's Small/Thiele parameters are, purposefully added the scant amount of polyfil found in those ported boxes because that's what's required to maintain proper tuning? Then the buyer comes along and adds x amount of polyfil and the box tuning shifts by x amount. If AA subs have a flawed design already, then I suppose adding polyfil isn't going to hurt something that isn't right to start with and might even correct it. But be careful, and listen for distortion or even worse bottoming out the sub when driven to excessively high spl levels.

[Fors*]

Originally Posted by rwojtalewicz

+1 Aramis109, that's a wise decision.

I can justify adding polyfil to a closed box which can extend the bass response if done properly by lowering the Qt for a box that is smaller than required for a specific driver by making the box effectively larger than its physical size, ie by volumetric expansion. That's good as long it achieves a Qt = 0.7 to 1.0. A Qt lower than that (say 0.5) will end up overdamping the driver especially if the driver's Qts is already low (0.3 to 0.4), and you will end up bottoming out the subwoofer possibly damaging it. Drivers with such low Qts are better suited to ported designs.

It's a bit different for ported designs though. Adding polyfil to a ported box is tricky because the box is tuned to a specific frequency (fb). I would only add polyfil to a ported design for the purpose of fine tuning it to the correct frequency required by that design for that particular driver. Adding too much or too little polyfil will alter the calculated box volume. If you alter the box volume, you change the tuning. Thus if you don't know the box tuning frequency, then how do you know how much polyfil to add? Trial and error, perhaps? Well maybe with enough patience. All I can say is, good luck to those who attempt it.

Now, the folks owning AA subs say that adding polyfil helps. Perhaps by chance or by coincidence it does. But what if AA HD sub designers who certainly know or should know what the driver's Small/Thiele parameters are, purposefully added the scant amount of polyfil found in those ported boxes because that's what's required to maintain proper tuning? Then the buyer comes along and adds x amount of polyfil and the box tuning shifts by x amount. If AA subs have a flawed design already, then I suppose adding polyfil isn't going to hurt something that isn't right to start with and might even correct it. But be careful, and listen for distortion or even worse bottoming out the sub when driven to excessively high spl levels.

Very interesting post....like I said before, I learn something new on here all the time, thanks rwojtalewicz.

[duneaholic]

Originally Posted by rwojtalewicz

+1 Aramis109, that's a wise decision.

I can justify adding polyfil to a closed box which can extend the bass response if done properly by lowering the Qt for a box that is smaller than required for a specific driver by making the box effectively larger than its physical size, ie by volumetric expansion. That's good as long it achieves a Qt = 0.7 to 1.0. A Qt lower than that (say 0.5) will end up overdamping the driver especially if the driver's Qts is already low (0.3 to 0.4), and you will end up bottoming out the subwoofer possibly damaging it. Drivers with such low Qts are better suited to ported designs.

It's a bit different for ported designs though. Adding polyfil to a ported box is tricky because the box is tuned to a specific frequency (fb). I would only add polyfil to a ported design for the purpose of fine tuning it to the correct frequency required by that design for that particular driver. Adding too much or too little polyfil will alter the calculated box volume. If you alter the box volume, you change the tuning. Thus if you don't know the box tuning frequency, then how do you know how much polyfil to add? Trial and error, perhaps? Well maybe with enough patience. All I can say is, good luck to those who attempt it.

Now, the folks owning AA subs say that adding polyfil helps. Perhaps by chance or by coincidence it does. But what if AA HD sub designers who certainly know or should know what the driver's Small/Thiele parameters are, purposefully added the scant amount of polyfil found in those ported boxes because that's what's required to maintain proper tuning? Then the buyer comes along and adds x amount of polyfil and the box tuning shifts by x amount. If AA subs have a flawed design already, then I suppose adding polyfil isn't going to hurt something that isn't right to start with and might even correct it. But be careful, and listen for distortion or even worse bottoming out the sub when driven to excessively high spl levels.

Dude you may be onto something. I may indeed take out some more polyfill. I am having distortion and didn't really notice it before I did it....but this was what came in it and couldn't be right...this looks like a quality control issue...I may be taking the poly out of the PA as well.




This is after I put the polyfill in...it has more in it now after this pic too....it fills the back area in now... My sub seems to be bottoming out and has no sound in the 20-25hz range.

[Big Daddy]

Originally Posted by rwojtalewicz

+1 Aramis109, that's a wise decision.

I can justify adding polyfil to a closed box which can extend the bass response if done properly by lowering the Qt for a box that is smaller than required for a specific driver by making the box effectively larger than its physical size, ie by volumetric expansion. That's good as long it achieves a Qt = 0.7 to 1.0. A Qt lower than that (say 0.5) will end up overdamping the driver especially if the driver's Qts is already low (0.3 to 0.4), and you will end up bottoming out the subwoofer possibly damaging it. Drivers with such low Qts are better suited to ported designs.

It's a bit different for ported designs though. Adding polyfil to a ported box is tricky because the box is tuned to a specific frequency (fb). I would only add polyfil to a ported design for the purpose of fine tuning it to the correct frequency required by that design for that particular driver. Adding too much or too little polyfil will alter the calculated box volume. If you alter the box volume, you change the tuning. Thus if you don't know the box tuning frequency, then how do you know how much polyfil to add? Trial and error, perhaps? Well maybe with enough patience. All I can say is, good luck to those who attempt it.

Now, the folks owning AA subs say that adding polyfil helps. Perhaps by chance or by coincidence it does. But what if AA HD sub designers who certainly know or should know what the driver's Small/Thiele parameters are, purposefully added the scant amount of polyfil found in those ported boxes because that's what's required to maintain proper tuning? Then the buyer comes along and adds x amount of polyfil and the box tuning shifts by x amount. If AA subs have a flawed design already, then I suppose adding polyfil isn't going to hurt something that isn't right to start with and might even correct it. But be careful, and listen for distortion or even worse bottoming out the sub when driven to excessively high spl levels.

What is the source of your information? The only benefit of polyfill is not to make the subwoofer larger.

If the purpose of this post was to knock AA subs, that is bad manners. As a general rule, we do not knock other people's equipment. Why single out AA subs? Folks at ED, Polk, SVS, etc. threads have added polyfill to their subwoofers and reported an improvement. I know of some people who have added polyfill to their speakers and were very happy with the results.

BENEFITS OF POLYFILL

It is a good idea to use sheet dampening material to cover the entire inner surface of the cabinet. A small amount of glue may help. The loose polyfill is good for filling the cabinet. The type of subwoofer (down-firing or front-firing) does not play a role.

Polyfill can have several positive effects:

• It will dampen the cabinet.
• You will hear less noise, particularly the noise associated with the flow of air through the port.
• It will slow down the sound waves and makes the enclosure appear larger. When polyfill is added to an enclosure, it changes the behavior of the airflow in the enclosure from "adiabatic" to "isothermal". The term "adiabatic" means that there is no heat transfer occurring. An isothermal process means that as the air passes through the polyfill, the fibers wiggle and cause some of the energy created by the air to be dissipated as heat. This heats the surrounding air molecules warmer, causing the air to become less dense. Sound waves travel easier through a denser medium. As a result, the driver interacts with the enclosure as if it is larger than it actually is.
• Larger cabinets are more efficient and as a result low frequency extension of the sub will be lowered. It will also lower the resonant frequency of the port.

Adding polyfill to an enclosure is a good idea. However, too much polyfill can be a bad thing. At a certain point, the stuffing becomes too dense and the fibers no longer wiggle. At this point, not only have you taken away the size benefit of adding polyfill, you have actually decreased the effective volume as the polyfill is now taking up room inside your enclosure. You should add anywhere between 1/2 pound to one pound of polyfill to one cubic feet of enclosure.

The following diagram from Basic Car Audio demonstrates the effect of polyfill on the frequency response of a subwoofer.

Poly-fill can be used to make an enclosure seem slightly larger. It does this by slowing the movement of the air in the enclosure. This, in effect, smoothes the frequency response of the subwoofer's output and slightly improves its low frequency extension. This image shows, to what degree, it does both. The red line (no fill) has a slightly higher peak than the yellow line before it starts to roll off. The yellow line has a slightly improved low frequency extension when compared to the red line. The effect is not very dramatic but using poly-fill in this manner can sometimes make a subwoofer sound better. The red curve is has no poly-fill. The yellow line is 100% filled with poly-fill. 100% fill is equal to 1 pound of poly-fill per cubic foot of air space.

As was stated earlier, polyfill has these three main effects on a subwoofer box:

• It dampen the box and reduces the effect of back waves.
• It makes the enclosure appear to be larger than it actually is.
• It slightly lowers the tuning frequency of the ported subwoofer.

Pollyfill is a sound absorption dampening fiber that may deepen the sound and tone down any unwanted reverberation of any subwoofer. Contrary to all the nonsense that is repeated in most Internet forums, we do not have standing waves in a subwoofer box, particularly in HT applications. Assuming that the vast majority of subwoofers for home audio are crossed at 80Hz to 100Hz, you can imagine the stupidity of this claim. These are the approximate wavelengths of bass frequencies:

20Hz: 56.5ft
50Hz: 22.6ft
80Hz: 14.1ft
100Hz: 11.3ft

For standing waves to occur, we need a subwoofer that is the size of a room. How many of you have a subwoofer that big?

Polyfill affects both sealed and ported subwoofer boxes. As a general rule, polyfill has more benefit for small boxes and since most sealed boxes are smaller than ported boxes, it appears that sealed boxes are affected more.

In car audio, most people play bass-heavy music at loud volumes and the subwoofers are tuned at a higher frequency for maximum SPL. They are more concerned about loudness.

In home audio, most people care about the quality of audio for HT and music applications. Most HT subwoofers are tuned lower for better low frequency extension.

This is from Ultimate Polyfill Subwoofer Enclosure Resource

To evaluate the effectiveness of box stuffing, I used an MLSSA analyzer to measure the impedance of three enclosures 5.l-cubic-foot sealed, 1.4-cubic-foot sealed, and 1.4-cubic-foot ported (the port measured 3 inches in diameter and 6 inches in length) with various densities of stuffing. For the sealed boxes, I was able to determine the effective box size as enhanced by the stuffing using the system's resonant-frequency and Qes values. For the ported box, I compared the tuned frequency of the empty enclosure to the tuned frequency of the stuffed enclosure, using the Speak for Windows computer program; this enabled me to find the effective box size that fit the actual resonant frequency I'd measured.

Sealed Box (1.4 cubic ft ):


Sealed Box (5.1 cubic ft):


Ported Box (1.4 cubic ft):

Usually about 1/2 pound to a maximum of one pound of polyfill per one cubic ft is enough. Over-stuffing a subwoofer box may have a negative effect. Some people suggest that you experiment with the amount of polyfill until you get the desired effect.

It is a good idea to staple or glue a thin layer of polyfill to all the interior panels of the subwoofer box and add sufficient amount of loose polyfill to the box. Remember that if you put too much loose polyfill inside a ported subwoofer, it may lower the sound quality and the polyfill may blow out of the port.

Although fiberglass can also be used, I do not recommend it as it can become a health hazard.

Polyfill can also have a positive effect on regular speakers. Speakers are more subject to back standing waves as the drivers generate much higher frequencies (lower wavelengths).

[Yeha-Noha]

Originally Posted by aramis109

Heh, finally. I'll add you to the list.

rwojtalewicz (man, I always have to copy your name- can't spell that!) thanks for the great pics. That's the first quality shot I've seen of hte cherry finish. Looks really good. You mentioned the fuse- made me realize I think I threw mine away on accident. DOH! I'll have to check and see if I still have it. Your comment on the grill is spot-on- I took mine off once to look at it and won't do it again. You really have to pry at it, but on the plus side it sits very flush against the cabinet. Glad you're happy with yours.

Sorry about that. That's our old family name from Warsaw, Poland ca. 1831. It's a completely different Anglicized name now though. I just like using our old country name to identify with my European ancestry on my dad's side.

BTW, wojta or rwojta will do for short.

Back to topic, not only was there an extra fuse supplied, but also a L/R 12 ft long audio cable with RCA plugs. Those seem to be too small in diameter to have proper shielding for such a long run. I used a regular better shielded coaxial cable with RCA plugs to hook up my PA 120.

I really don't need to take off the speaker grille. But when I take photos of my gallery, it would look cool with the grille removed.

[Yeha-Noha]

Originally Posted by Big Daddy

What is the source of your information? The only benefit of polyfill is not to make the subwoofer larger.

If the purpose of this post was to knock AA subs, that is bad manners. As a general rule, we do not knock other people's equipment. Why single out AA subs? Folks at ED, Polk, SVS, etc. threads have added polyfill to their subwoofers and reported an improvement. I know of some people who have added polyfill to their speakers and were very happy with the results.

BD, I'm not knocking AA subs, PA subs, SVS, or eDs. I'm just trying to make sense out of the practice of adding polyfil. It wasn't my intention to offend you or anyone else. I'm learning. I appreciate your taking time to discuss this in dept. I was only going on what I learned.

My source was:

Weems, David, 1978, How to Design, Build, and Test Complete Speaker Systems. Chapters 5 - 7.

Here's my question to you which still hasn't been answered:

If subwoofer enclosures need polyfil, then why don't they have the proper amount added to begin with? That's my contention. It seems like a design flaw to me if they don't. That goes for any manufacturer be they PA or SVS.

[Big Daddy]

Originally Posted by rwojtalewicz

BD, I'm not knocking AA subs, PA subs, SVS, or eDs. I'm just trying to make sense out of the practice of adding polyfil. It wasn't my intention to offend you or anyone else. I'm learning. I appreciate your taking time to discuss this in dept. I was only going on what I learned.

My source was:

Weems, David, 1978, How to Design, Build, and Test Complete Speaker Systems. Chapters 5 - 7.

Here's my question to you which still hasn't been answered:

If subwoofer enclosures need polyfil, then why don't they have the proper amount added to begin with? That's my contention. It seems like a design flaw to me if they don't. That goes for any manufacturer be they PA or SVS.

Some manufacturers add none. Some add a little. Others add plenty. For example, my Hsu cylindrical subwoofers that I purchased over 10 years ago have plenty of polyfill. The AA sub has some on the interior surface of the box. Parts Express sells expensive polyfill for around $10 a bag. Of course, Wal-Mart sells more generic and cheaper polyfill.

Maybe, it is the expense of material, time, and labor. It is like all other after market products. For example, we have thousand of manufacturers that sell after market products for cars. You can ask the same question. Why didn't the car manufacturers do it at factory?

[Big Daddy]

Originally Posted by duneaholic

Dude you may be onto something. I may indeed take out some more polyfill. I am having distortion and didn't really notice it before I did it....but this was what came in it and couldn't be right...this looks like a quality control issue...I may be taking the poly out of the PA as well.

This is after I put the polyfill in...it has more in it now after this pic too....it fills the back area in now... My sub seems to be bottoming out and has no sound in the 20-25hz range.

I don't believe the problem you are having has anything to do with polyfill. Polyfill normally lowers the low-end frequency (see curve above). I added polyfill to my AA sub and it had plenty of sound at 20Hz and 25Hz. As I told you before, at 25Hz, the room started vibrating. It was scary. It was probably the room resonance frequency.

My guess is that you have a faulty driver or another issue.

[callas01]

BD, do you have a degree in Home Theatre Science? and where the heck did you get it from?

[Yeha-Noha]

Originally Posted by Big Daddy

Some manufacturers add none. Some add a little. Others add plenty. For example, my Hsu cylindrical subwoofers that I purchased over 10 years ago have plenty of polyfill. The AA sub has some on the interior surface of the box. Parts Express sells expensive polyfill for around $10 a bag. Of course, Wal-Mart sells more generic and cheaper polyfill.

Maybe, it is the expense of material, time, and labor. It is like all other after market products. For example, we have thousand of manufacturers that sell after market products for cars. You can ask the same question. Why didn't the car manufacturers do it at factory?

Why? People have better car sense I suppose. It's a weak comparison because the car market is just that, a humongous after market. Except for spikes, risers, acoustic isolation pads, and cables, maybe a few other items, the after market for subwoofers isn't anything close to the auto industry just a niche at best. I would think that the common consumer buying a subwoofer expects it to be plug and play. If you tell them they have to take the guts out to add polyfil, do you think they would buy it? I don't mean you, me, and all the other sub enthusiasts on this forum, but Mr. J6P. When it comes to cars, I think Mr. J6P knows what he's buying and what he might want in the future to make it perform better. But after buying a subwoofer, and he's likely to go budget, is he going to know that he needs to add polyfil for a performance gain?

For expensive high end subs, it's a non issue. Pay more, expect more. I wouldn't want to open the cabinet of a $800 + subwoofer to add polyfil that should already have been added in the first place.

[Big Daddy]

Originally Posted by callas01

BD, do you have a degree in Home Theatre Science? and where the heck did you get it from?

No, I have a B.S & M.S. in engineering specializing in materials science and a Ph.D. in Managerial Economics.

I have also owned many different types of equipment, visited many audio/video stores, and attended many A/V shows since the day Thomas Edison invented electricity. On top of that, I have subscription to every A/V and phtography/video magazines and spend hours doing all sorts of research on the Internet.

[duneaholic]

Originally Posted by Big Daddy

I don't believe the problem you are having has anything to do with polyfill. Polyfill normally lowers the low-end frequency (see curve above). I added polyfill to my AA sub and it had plenty of sound at 20Hz and 25Hz. As I told you before, at 25Hz, the room started vibrating. It was scary. It was probably the room resonance frequency.

My guess is that you have a faulty driver or another issue.

I'm not done tweaking yet. I may have to take you up on your offer on the driver. It didn't do as well on Hulk as I liked although it was much much better.

[duneaholic]

Originally Posted by Big Daddy

No, I have a B.S & M.S. in engineering specializing in materials science and a Ph.D. in Managerial Economics.

I have also owned many different types of equipment, visited many audio/video stores, and attended many A/V shows since the day Thomas Edison invented electricity. On top of that, I have subscription to every A/V and phtography/video magazines and spend hours doing all sorts of research on the Internet.

And it shows with all the painstaking research you have done and put into "stickies". I am really thankful for it...it's helped me a ton!

[Big Daddy]

Originally Posted by rwojtalewicz

Why? People have better car sense I suppose. It's a weak comparison because the car market is just that, a humongous after market. Except for spikes, risers, acoustic isolation pads, and cables, maybe a few other items, the after market for subwoofers isn't anything close to the auto industry just a niche at best. I would think that the common consumer buying a subwoofer expects it to be plug and play. If you tell them they have to take the guts out to add polyfil, do you think they would buy it? I don't mean you, me, and all the other sub enthusiasts on this forum, but Mr. J6P. When it comes to cars, I think Mr. J6P knows what he's buying and what he might want in the future to make it perform better. But after buying a subwoofer, and he's likely to go budget, is he going to know that he needs to add polyfil for a performance gain?

For expensive high end subs, it's a non issue. Pay more, expect more. I wouldn't want to open the cabinet of a $800 + subwoofer to add polyfil that should already have been added in the first place.

Do not mention an average person because an average person would be happy with an HTIB and wouldn't know the difference between HD audio and chicken soup.

Crazies like us are different and waste a large portion of our lives experimenting and worrying about things that may or may not have a significant effect. I have been tweaking and doing crazy things to electronics, computers, cameras, etc. for more than 30 years. I change speaker/subwoofer drivers, crossovers, and amplifiers without a moments of hesitation. An average person buys a subwoofer and puts it in the room without knowing anything about placement or standing waves.

That also applies to car after-market products. The vast majority of people buy a car and drive it. Only a few nuts will put crazy subwoofers or add truck-size tires to their cars.

[Yeha-Noha]

Originally Posted by callas01

BD, do you have a degree in Home Theatre Science? and where the heck did you get it from?

He might be an audio engineer and a respected member of the AES (Audio Engineering Society).

BD seems to be well versed in the subject and knows where to find the resources to backup what he says. I find it hard to argue with that. We all can learn from BD whether he's AE or not.

Interpreting the data that he posted is another story. I see that the addition of polyfil might be beneficial, but it can also decrease performance unless you know what you are doing.

[callas01]

Originally Posted by Big Daddy

No, I have a B.S & M.S. in engineering specializing in materials science and a Ph.D. in Managerial Economics.nice, puts my BS in Business Admin to shame..

I have also owned many different types of equipment, visited many audio/video stores, and attended many A/V shows since the day Thomas Edison invented electricity. On top of that, I have subscription to every A/V and phtography/video magazines and spend hours doing all sorts of research on the Internet.

I got you... I know you live near my in-laws at the San Bern foothills... I need to stop and see you sometime... you near northpark? I would love to meet you and see your setup. you are one interesting man...

[Big Daddy]

Originally Posted by callas01

I got you... I know you live near my in-laws at the San Bern foothills... I need to stop and see you sometime... you near northpark? I would love to meet you and see your setup. you are one interesting man...

I sent you a PM.