Is there a way to measure polyfill accurately?

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Comments

  • machonemachone Posts: 971
    Take it easy man I was just kidding.
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  • Dredged posts are -thebest-

    @Jstas Thanks John, that's way more comprehensive than what my understanding of stuffing ever was. Thanks for the writeup. I guess us IT people can fly a bit on the keys, but here it's definitely appreciated.

    Back in my mobile SQ days we did all kinds of foam, dynamic mat, and fluff to change resonances of trim panels, the cabin, and dampen body cavities. A customers' SQ problem was seldom in the driven system. The 'professional' setups the SPL guys would sell and install to anyone with a money burning a hole in their pocket had the power and components needed just minus the brains. They'd listen to it and get tired of cabin rattle and come back and see Len or me to clean it up... We'd calculate the cabin as if it were a speaker enclosure itself, and they're just a nightmare usually.

    On the built enclosures we often just lined the corners and any bracing on the inside with stiff poly-fill and the flat MDF areas would get a few layers of DynaMat... tbh, the Dynamat cleaned them up more than the fluff. Poly-fill in a ported or passive enclosure was just a no-no, but we'd see them come in all the time like that, and sealed under-sized boxes failed from overheated coils with melted polyfill or unglued spiders, etc. Just better to eat the space requirement and build the enclosure correctly. I would say cheaters never prosper... but they do, just not for long.
  • Viking64Viking64 Posts: 2,796
    Jstas wrote: »
    machone wrote: »
    How can you type that much!!!!

    This is completely uncalled for and why I don't post much anymore. I go through all this effort to help some people out because I can. Then I get mocked and dumped on because I took some time out of a lunch break to provide an answer with complete thoughts formed with proper grammar, spelling and punctuation. All because it's beyond your comprehension that someone can form a complete answer and explain complex concepts with a keyboard.

    I don't believe anyone was mocking you or dumping on you. I was the first to respond with an image, as if the dog was saying: "Holy crap! That is a lot of information about polyfill." It was in no way intended to discredit you or ridicule you.

    I understand how much effort you put into your 2 posts and I can see how it may seem like it wasn't appreciated. The fact remains that we now have a permanent document detailing specifics of an often overlooked aspect of speaker dynamics that can be accessed and utilized for years to come.

    I am currently in the process of modding a pair of 2.3TL's. I had everything, save for the crossovers, removed from the cabinets. One "roll" of the original polyfill in each cabinet had fallen down to about midway of the diameter of the passive radiator. After sealing them with Power Grab and adding BlackHole5, I put them back together and the sonic improvements were substantial.

    At that time, the best advice I found on here, after installing the BlackHole5, was: "reinstall the polyfill" and "keep it out of the area of the PR". Your knowledge would have been invaluable to me then and is is sure to be for many others in the future. Your efforts are a perfect example of why this forum is great.
  • lightman1lightman1 Posts: 9,660
    Viking64 wrote: »
    Jstas wrote: »
    machone wrote: »
    How can you type that much!!!!

    This is completely uncalled for and why I don't post much anymore. I go through all this effort to help some people out because I can. Then I get mocked and dumped on because I took some time out of a lunch break to provide an answer with complete thoughts formed with proper grammar, spelling and punctuation. All because it's beyond your comprehension that someone can form a complete answer and explain complex concepts with a keyboard.

    I don't believe anyone was mocking you or dumping on you. I was the first to respond with an image, as if the dog was saying: "Holy crap! That is a lot of information about polyfill." It was in no way intended to discredit you or ridicule you.

    I understand how much effort you put into your 2 posts and I can see how it may seem like it wasn't appreciated. The fact remains that we now have a permanent document detailing specifics of an often overlooked aspect of speaker dynamics that can be accessed and utilized for years to come.

    I am currently in the process of modding a pair of 2.3TL's. I had everything, save for the crossovers, removed from the cabinets. One "roll" of the original polyfill in each cabinet had fallen down to about midway of the diameter of the passive radiator. After sealing them with Power Grab and adding BlackHole5, I put them back together and the sonic improvements were substantial.

    At that time, the best advice I found on here, after installing the BlackHole5, was: "reinstall the polyfill" and "keep it out of the area of the PR". Your knowledge would have been invaluable to me then and is is sure to be for many others in the future. Your efforts are a perfect example of why this forum is great.

    Buttkisser.....
  • Viking64Viking64 Posts: 2,796
    lightman1 wrote: »
    Buttkisser.....
    6apa10gaph03.jpg

  • Toolfan66Toolfan66 Posts: 13,780
    I wish I had the skills to type like that, I for one appreciate the work and time you took to post that info. It would have taken me half the day with my typing skills..
  • ken brydsonken brydson Posts: 7,008
    edited December 2017
    Reported... Buh bye now...
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  • xschopxschop Posts: 828
    Read first reply, stopped for coffee break, then read 2nd. Very concise points, thank you. I love my Power-ported SDA's.
  • stainless0steel2stainless0steel2 Posts: 147
    edited January 1
    What happens if you add Black hole 5 behind the drivers in let's say a set of SDA 2B's. Do you still need some of the polyfill behind those drivers?
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  • Tony MTony M Posts: 5,580
    @Jstas's very detailed explanation of whether or not to add or reduce or leave it be on speaker polyfill should be put at the top of the list in the Category of speaker tweaks and mods. Permanently.

    Very , very informative ! I've seen my fair share of speaker box / tower interiors that I can say the fill in them has been so varied that I believe, like John states, each has been unique without a doubt.

    Reading the explanations in John's post was like taking an advanced class on "Dampening a speaker enclosure" but taught in a way as to explain the theories and facts to my elementary level of knowledge on the subject.

    Thanks John !

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  • F1nutF1nut Posts: 39,972
    What happens if you add Black hole 5 behind the drivers in let's say a set of SDA 2B's. Do you still need some of the polyfill behind those drivers?

    You need all of the original polyfill.
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  • JstasJstas Posts: 13,662
    The polyfill in SDAs is not there for driver dampening. It's there for port tuning.

    SDAs have passive radiators which is essentially a speaker port.

    Ports work because they have a column of air in them that gets moved when the driver vibrates. That moving air in the port creates complimentary sound waves that enhance the performance of your speaker. Just like how you can feel and hear the THWHUMP of air when you shut a car door or when you shake a trashbag to open it up. The same thing happens with a port.

    Port tuning is essential because you need to be able to get the maximum flow rates without hitting the cavitation point in that port to move the air and take advantage of the air spring it creates. If you move it too fast you will either compress the air in the port and enclosure too much and possibly cause physical distortion in some or all of the drivers. Alternatively, you will blow all the air out of the port and create a vacuum in the enclosure which can also cause physical distortion, attenuated performance of the driver and even cause overheating issues in the motor structure.

    Port tuning means that you have an appropriate amount of air in the port and enclosure, it's weighted properly to compliment the drivers because of the port size and it's moving at the highest rate possible before cavitation or other performance killing phenomenon happen.

    A passive radiator does the same thing as a port but instead of a column of air, you have a rigid, polymer disc (which is actually a cylinder) that takes the place of the air. It does the same thing which is why they have to be weighted properly so they don't move too fast or too far and make farty distortion noises.

    So like a ported enclosure uses polyfill to make a box and port perform well by changing the velocity of the air being moved by the backwave off the rear of the driver, polyfill in an SDA evens out the velocity of the backwave pressure inside the enclosure. That makes the air pressure work evenly on the rear surface of the passive radiator so you get nice, tight bass response without having to have a giant driver or getting the flappy, **** noise from distortion rippling across the surface of the passive radiator.

    The benefit there is that you can have a crazy, complicated load to drive in a fancy crossover network like what is needed to drive the SDA tech and you can reduce or at least make the load more reasonable by having small, efficient, easy to drive drivers. That way you get your SDA wizardry but you have a huge tower speaker that performs on the high end like a 2-way bookshelf but digs deep like 15 inch sub and can do it on 200 watts per channel for the entire array, not just the sub.
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  • pkquatpkquat Posts: 576
    @Jstas Excellent posts. TY. I keep forgetting to mention that in my drive by's of late.
  • verbverb Posts: 2,732
    Thanks @jstas and @f1nut I think I found my answer for my 1C upgrade path. BH5 just behind the MW's and re-install the original polyfill. Correct?

    http://forum.polkaudio.com/discussion/179960/another-1c-upgrade-path#latest
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  • pitdogg2pitdogg2 Posts: 10,217
    verb wrote: »
    Thanks @jstas and @f1nut I think I found my answer for my 1C upgrade path. BH5 just behind the MW's and re-install the original polyfill. Correct?

    http://forum.polkaudio.com/discussion/179960/another-1c-upgrade-path#latest

    Yes it is good stuff.
  • FestYboyFestYboy Posts: 2,521
    Reading @jstas 's post finally explained why I'd witness sub drivers wobble when viewed in slow-mo. I always wondered what was causing such nonlinear motion. Now I can use this to help remedy some mods I had in mind for the 505s.
  • wolfie62wolfie62 Posts: 22
    I knew there was a reason I don't use fiberglass or polyfill! I use a damping material to kill cabinet coloration, but not fiber stuffing.
    Invention is the mother of necessity.

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  • Viking64Viking64 Posts: 2,796
    wolfie62 wrote: »
    I knew there was a reason I don't use fiberglass or polyfill! I use a damping material to kill cabinet coloration, but not fiber stuffing.

    Fiberglass insulation makes for a relatively poor sound control product.
  • ClipdatClipdat Posts: 4,209
    That must be why they use it in car mufflers.
    Viking64 wrote: »
    Fiberglass insulation makes for a relatively poor sound control product.

    Got Dayens?
  • Viking64Viking64 Posts: 2,796
    Clipdat wrote: »
    That must be why they use it in car mufflers.

    Fiberglass and fiberglass INSULATION. Big difference.
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