Rotary Subwoofer Install Blog

September 23, 2006

TRW exploded parts and assembled snaps…

Filed under: Uncategorized — bassment @ 8:11 am


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Point of no return

Filed under: Uncategorized — bassment @ 8:01 am


Now we start moving HVAC ducting around so as to make a wide open space for the TRW manifold box to sit on top of the bath/office ceiling, and blow into the media room. All that framing above in the second pic has to come out. The ducting in the third pic has to be moved, which was not trivial. Oh, and the ceiling fixture that was in the ceiling had to be converted to wall sconces. Also note the office door leading up the ground level… if needed, we can vent the backside of the woofer through a screen door here.


Bruce Thigpen taking measurements… the TRW install has to be done in motion, as we open up the ceiling and walls, we get more visibility into what can be done with what dimensions.


All of the framing and drywall above will need to go… this separates the media room from the office/bath ceiling.


The drywall surrounding the soffit has been removed.


So now we have removed all the drywall on the soffit, the soffit framing, the soffit, and the drywall sealing the media room off from the office. Notice the 30 degree angle… Bruce wanted a flare opening as the air pressure waves enter the media room, because it improves the efficiency of the TRW, which results in more SPL at VLF.

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Point of no return

Filed under: Uncategorized — bassment @ 7:45 am

When we actually demo the soffit and punch a hole through the media room wall, then we’re not turning back. It took some consideration to get this point. Before today, the media room was air-tight… non trivial expenses, such as the magnetically sealed IAC sound doors, were undertaken to keep the room air tight, to minimize sound incursion/leakage. Now that will be partially compromised, because the media room will have an air pathway between the media room and the bath/office, and possibly the garage and/or garage attic.

However, in the pursuit of maximum bass, nothing shall stand in our way, even reasonableness.

In the leftmost picture below, you can see the soffit before we start the demolition, in the upper left corner of the photo. These pics were taken Thursday 21, 2006.


So there it is… the soffit is down, and the point of no return has been reached. Next step is to breach the drywall above Bruce’s head in the right most picture.

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Point of no return – the demolition starts

Filed under: Uncategorized — bassment @ 7:34 am


First thing to do, before Bruce and Winston arrived from CEDIA, was to have the bath and office ceiling removed. Above, one of our demo team tapes the media room IAC sound door, and the cherry cabinets where all the CD’s, vinyl and DVD’s are kept.


Better to score the drywall with a knife, instead of the Sawz-all. The knife method cuts way down on dust. Now reaching the point of no return!


The media room office ceiling is down… still we can easily repair this, so we can still easily turn back.


Above you can see the office ceiling clear, with some framing yet to remove, and the bathroom behind it. Also now cleaning up the mess.

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Installing the TRW – the implications

Filed under: Uncategorized — bassment @ 7:15 am

Installing the TRW into an already finished room is no simple feat. The TRW must stride a boundary between the room of interest and a sufficient back space volume. For an existing home theatre, this means cutting into a or ceiling, no other way around it! For my particular situation, since I am underneath a garage, the ceiling was out. The walls were out, because on the other side of the drywall is 12″ concrete, then mother earth.

Except for one wall – the wall leading to a basement popout which houses a half bath and a small ‘office’. It was the wall between the media room and the bath that Bruce and I focused on the possibility of installing the first ever TRW. It turns out that there is an HVAC chase that runs between basement and the garage and garage attic, and this chase is pretty wide (12-15 sq feet) and starts above the bathroom ceiling corner.

So we decided, that if we could install the TRW(s) above the media room bathroom ceiling, pushing air into the media room at ceiling height, that we could then backport the TRW into the media room bath/office (via a ceiling grate) and also into the garage and garage attic via the HVAC chase. Of course, the HVAC chase is not fully available to move air in and out because about half of it is occupied by fat 14″ SoundCore plenums.

But this was and is the only possibility to meet the unique install requirements of the TRW. As a last ditch backup, we could always install a screen door on the media room office external door (leading up to the ground level), and let the TRW’s vent to the outdoors. But that is not preferable (though it is optimal from a performance point of view) since the VLF pressure waves have a chance of being noticed by neighbors, as during the demo.

All this boils down to readily accepting the fact that one will have to do serious room surgery. Demolition of framing, drywall, the resulting dust, possible unforeseen damage to equipment, etc… The best way to get over that anxiety is to bash open a few pieces of drywall and get way past the point of no return.

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September 22, 2006

BAAS Demo of the Thigpen Rotary Woofer (TRW)

Filed under: Uncategorized — bassment @ 11:16 am

Bruce Thigpen and Winston Wright flew out on the Eminent Technologies corporate aircraft, complete with one TRW-17 rotary subwoofer and all the necessary installation retrofit needed to temporarily affix the TRW (we’ll refer to the new sub unit by TRW from here on out) to a door leading to my media room.

Bruce and Winston were very careful in crafting the temp install… the TRW, unlike all conventional subwoofers, needs a large space behind the room it is pushing air in and out of. In my case, we used the great outdoors as the back vent space. More on that later. So we installed the TRW into a doorway which then leads into a media room office. Winston constructed a nice temporary baffle to redirect the air pressure waves around the corner into the media room, via a temporarily open IAC studio grade sound door.

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The purpose of the demo was to install, for the first time, the TRW into a real home theatre, and try off the shelf DVD content, and see if the TRW made any noticeable difference. Bruce had prepared cuts from about 10 DVDs that he found had good sub 20Hz content. DVD’s with plenty of sub 20Hz content are not very common, but quite fortunately many of the action and suspense type films do integrate quite a bit of the VLF (we’ll refer to sub 20Hz content at VLF from now on). Perhaps for the purpose of seat shakers? Who knows, but the VLF is certainly there, as can be measured by analyzing the DD or DTS soundtrack.

Bruce ran through the clips with and without the TRW in the system. Mind you, this is comparing the Wilson XS and two Wilson Watchdogs with and without the TRW… so the TRW better do something significant to add to these three powerful subs. The audience consisted of several of SF Bay area members. We also invited Keith Yates who attended. Keith is THE eminent high end home theatre designer/acoustician in California, if not the world. His knowledge on acoustics and all things home theatre is unsurpassed. You can read the comments on the AVSForum thread where we discussed audience reactions.

Suffice to say the difference the TRW made was quite significant. After seeing/hearing with the TRW, the Vogon’s destruction of Earth scene in HHGTTG was empty and hollow with just the three subs, almost devoid of the rumbling that the TRW provided. The cannon shots in Master Commander were OK before the TRW, hitting you in the but. With the TRW, the cannon shots were shockingly violent. You were absolutely there in the cannon bay of the British man’o’war, getting a concussion from the black powder cannon blast. WOW! After these clips, I simply HAD to HAVE this TRW IN MY THEATRE!

Also, it’s worth noting that the official demo attendees were not the only to enjoy the virtues of VLF at high SPLs. Turns out we had some unintended attendees… namely my neighbors about 1000ft away. As was related by this neighbor (who I had not met before this demo nite), she and her cul-de-sac neighbors were walking around the neighborhood wondering what was shaking their walls and rattling their pictures. It was a slow shaking she said, much like an earthquake, except it kept going on and off for hours during the day. So she and her son started wandering the neighborhood looking for what was the source of this wierd vibration. Well, by trial and error she found out house, and I fessed up. Of course, I took her and her son down the the bassment for a demo, and she turned into an avid fan (no pun intended) and wondered how she might get one of these for their home theatre.

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Some YouTube video links: TRW subwoofer in action

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Media Room before new subwoofer technology…

Filed under: Uncategorized — bassment @ 11:16 am


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Why this blog…

Filed under: Uncategorized — bassment @ 10:30 am

I have been focusing on low frequency sound reproduction in my home theatre ever since I first powered it on. I have three subwoofers in the room right now… a 700lb Wilson XS powered by a 2400 Watt Crown K2 amp, and two (400lb) Wilson Watchdog powered subs. A few pics of the media room as of one week ago are posted up above.

But such subwoofery was not sufficient. Yes, there was plenty of low bass. I did tune the sub placement by using the EFT spectrum analysis software, and did get a nice flat response from 20-80Hz. SPL (sound pressure level) seemed reasonable, but still I lfelt there was more to do… something seemed to be missing. If we’re going to the trouble and expense of creating a high end theatre, we want raw reality to permeate our senses. I believe that just crisp sound and video is not enough – you must reproduce nature’s effects in their fullness. Certainly I have decent enough speakers to create SPL from 20Hz to 20kHz.

Perhaps the missing piece was creating SPL at the lower end of the subwoofer range of sound, below 20Hz limit of existing subwoofer technology. However, what could I do here… add more Wilson XS subwoofers? Each one is the size of a fridge… one is enough! So I basically stopped innovating in the room… vaguely unhappy with the low frequency outcome.

I ran across a mention of something new in the extreme bass world called the Rotary Woofer. Some offbeat inventor had shown up at the Rocky Mountain Audio Festival in 2005 with some newfangled invention that promised to provide prodigious amounts of bass from 20Hz down to 0Hz. Hmm… 0Hz indeed. From the scant online writeups about the demo, attendees had been visibly impressed by what they saw or felt.

OK, I bit… I emailed the inventors website. We exchanged messages, and I offered my underground home theatre as a demo, should he ever come out the West Coast (he’s in Florida). Silicon Valley being a fertile ground for suckers or customers of such technology, the inventor put together a demo and flew out with his able bodied assistant to showcase this technology, for the first time, in an actual home theatre.

So here, the story begins, with the actual demo day, in the context of the Ultra Hi End AudioForum where many Bay area audio nuts hang out online.

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