Best Stuffing for Speakers Tested - Unexpected Results

Comments · 470

• IB

  @IBuildIt · 4 years ago (edited) · pinned

  &quot;Best&quot; is a relative term. All three work, but if you prefer to use polyfil it&apos;ll get the job done. You just need to use more of it than the other two. <br> <br>And I&apos;m only looking at the ability of the stuffing to damp the interior of the box from the perspective of that one panel. The real difference between these is probably low enough that it really doesn&apos;t matter. <br>With that said, when compared by weight, fiberglass and rockwool nose out the polyfil by a small margin. <br> <br>My preference for fiberglass mostly came from almost always having some on hand. I like to use what I have and tend to be realistic about the differences between materials. Even if there is an audible difference, a difference doesn&apos;t necessarily mean one is better than the other. <br> <br>Moving on to direct panel damping, rubber damping was almost useless and doubling the panel thickness is effective but mostly down low. Double layer CLD is effective across the tested frequency range. I would consider that to be something worth doing if you are looking for peak performance. Like I said in the video, it can be combined with stuffing to make it even more effective. <br> <br>Important to put all of this in perspective. These differences are relatively insignificant when compared with other much more important design considerations when build a speaker. Driver selection, box design (volume, alignment) and crossover design are orders of magnitude more important to how the speaker will sound. <br>I do these tests to demonstrate just how small the difference actually is between these and how little they will affect the sound.

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• CH

  @chadridsdale9970 · 2 years ago (edited)

  I just found your Channel last night. My goodness do I appreciate what / how you are testing. I have a few projects that im procrastinating on and now im glad I did. Thank you

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• CH

  @ChonkTek · 3 years ago

  I did some tests 25 years ago with an SPL meter, two 12&quot; subwoofers in a sealed enclosure (trunk tire well enclosure) and various amounts of polyfill. &nbsp;I did individual frequency plots on a graph, 1Hz intervals. &nbsp;I found that adding polyfill decreased peaks and extended lows. &nbsp;There was a threshold where overall I started to lose some amplitude on all frequencies if I stuffed the enclosure too much. &nbsp;It was a great experiment to prove to myself that spikey response in a subwoofer can be tamed some.

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• MY

  @myturkishlife1777 · 4 years ago

  I have always been a fan of the &quot;CLD&quot; technique, have glued thicker MDF panels with silicone inside factory speaker enclosures many times always given good solid results.<br>Great video👍

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• TR

  @trevorbartram5473 · 4 years ago

  Two great videos, thanks! The preferred CLD method in UK DIY years ago was bituminous felt panels (a thick roofing product) covering all box internal surfaces. I built the Wireless World Tabor DIY design using Audax drivers using this technique in the late 70s. I had many comments regarding their excellent sound quality. When it comes to bracing, the matrix method first introduced by B&amp;W and, later, used by Paradigm is beyond the capabilities of most DIYers. It is used in my present speakers Paradigm Studio Monitor 30s purchased twenty years ago that I have never felt the need to replace. However, I must admit I&apos;m tempted by the KEF LS50 Metas with their use of a sculptured disc to absorb high frequency energy within the box, truly revolutionary and a tribute to British engineering.

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• MA

  @magnumcipher4971 · 1 month ago

  I thoroughly enjoy your content, no matter the subject. I&apos;ve been messing around with speaker enclosure design and construction for about 30 years now, and I learn something every time I watch. Thank you sir.

• TH

  @TheTherealdarkhorse · 4 years ago

  Polyfill is a fantastic sub killer. Gets shucked into the coil gap and overheats the subwoofer.

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• PA

  @patrickthunnus · 4 years ago

  I found it odd that the various stuffings weren&apos;t directly behind the woofer. I always thought the role of any stuffing was to absorb/diffuse the rearward wave of &nbsp;the cone and flatten the impedance curve, kinda like how the vintage dynaco speakers did with their aperiodic design. Every acoustic suspension speaker I&apos;ve ever opened up had the stuffing directly behind the woofer.

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• KE

  @kennethnielsen3864 · 4 years ago

  Thanks for sharing your thoughts and ideas.

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• SU

  @Subsonic-g2n · 4 years ago

  I would have put the stuffing right behind the woofer. &nbsp;Also, try lining the inside with No-Rez dampening material as a comparison to an empty box - I would,bet that this alone would make a huge difference. The rubber lining you placed was way too thin to make a difference. &nbsp;The CLD method sounds interesting by sandwiching silicone in between the wood, but you have also effectively doubled the thickness of the wood. I would be interested to see if glueing the two pieces of wood was just as effective than the silicone. &nbsp;Interesting tests, thank you for posting!

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• AU

  @AurasphereAcoustics · 1 year ago (edited)

  I really appreciate all you contribute to the community John. With this video, there are some real issues <br>1. You have the accel on a planar face that is not decoupled from the emitter<br>2. This means that the majority of the energy is transmitting usiing the mechanical box<br>3. As you increase the damping, it is an internal airspace mod in terms of the standing waves but in your case the transmission change is almost negligible because its still using the box as a wave guide of sorts to the top of the box...being a membrane.<br><br>I dont use any planar facings in any of the enclosures we do and they are proprietary masonry thats is extremely engergy absorbent (200mm can stop a 50 cal) and generally cast in a single piece.<br><br>BUT <br><br>Its quite amazing for tuning the boxes if there are critical issues<br><br>You can also do progressive damping by using acoustically inert diaphragms, tuning them to required freq and suspending them in the internal fill material which creates a type of hemholz if you really have issues esp in larger boxes. There is a noticeable choking that happens when I load a single driver sealed right up.<br><br>Great vids and always challenging!

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• VI

  @VioletGiraffe · 4 years ago

  Thank you for these tests, very interesting. I had the same idea as CLD, but I want to use vibration dampening materials from the car audio industry, they come in sheets with adhesive pre-applied, quite convenient to use and specifically designed for this task.

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