My Bass Story II - AVS | Home Theater Discussions And Reviews
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post #1 of 6 Old 04-05-2009, 11:47 AM - Thread Starter
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I started my quest for perfect bass in the summer of 2004. At that time I discovered Ethan Winer's wood DIY bass panel traps and the wonders of PEQ and the BFD.

Long time readers may remember my first bass story here:
http://archive.avsforum.com/avs-vb/s...hreadid=422490

I am now living in a new home and working on my HT version 2.0. For this thread, I now want to discuss the miracle of green glue and moving from a single sub to a dual sub setup.

I have a HSU TN1220 tube sub which is now discontinued although still highly regarded. I recently added a second TN1220. I have a parametric EQ BFD (you can read about the BFD here: http://bfdguide.ws/ ). I use Room EQ Wizard (REW: http://www.****************.com/roomeq/ ).

Here is my Story in annotated WaterFall LF Graphs. Waterfall graphs show the frequency response with a third dimension time added. With a waterfall graph you can easily see the effects of room modes and ringing.

Attached is my hometheater room, untreated, no EQ and a single sub, measured at my sweet spot (which happens to be in a somewhat bass unfriendly center of the room position).

Notice the uneven response and the ringing of bass especially near my room modes of 20hz, 40hz, and to a lessor extent 60 and 90 hz areas. The ringing is shown as bumps in the plot that extended outward in time towards you in the graph.

Notice the drop out of base between 40-65 hz as well. This drop is likely worsened because my listening position is near the middle of the room.

Looks and sounds pretty poor.
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post #2 of 6 Old 04-05-2009, 11:47 AM - Thread Starter
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Ok, now things start to get interesting. Can you say greenglue? (http://www.greengluecompany.com/)

My hometheater is in the basement, I have a drop ceiling. Above the ceiling is joists and the subfloor from the main level of the house. The main level living room had carpet in it and as part of a home update, we put in hardwood floors. My family had been complaining that the sound from the basement HT was going straight up thru the ceiling into the living room and was too loud!.

Primarly as a soundproofing measure, I had the hardwood installer put in a second 5/8" subfloor. Between the existing subfloor and the new subfloor I had the installer apply 2 tubes of greenglue for every 4x8 sheet of subfloor wood. Green glue is a great and easy to apply "goo" that serves to convert the vibrations caused by sound into heat energy. Read about it on the green glue web site.

However, the green glue had an unanticipated benefit to me. It turned my entire HT ceiling into a low frequency panel bass trap! If you view the waterfall graph below you will see significant attenutation of bass frequencies especially in the really low 30hz and below region. Note that the greenglue takes sometime to cure, this measurement was taken 4-5 months after application.

Note that the attached figure is in a basically otherwise untreated room with NO EQ filters applied.
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post #3 of 6 Old 04-05-2009, 11:47 AM - Thread Starter
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Ok, now it is time to see the effects of adding a second sub. I purchased a second used HSU TN1220 tube sub to go with my first one. You can colocate the subs in a corner if you want to enhance the output. But my purpose for the 2nd sub was to even out the response of the room. So I placed the two subs in separate locations in the HT.

Note in the attached graphs the effect of having the two subs. The 40-65hz hole is reduced and I am also getting a little extra low bass extension as well.

In the green/blue freq plot. The green line is a single sub, the blue line is the dual sub response.

Still no EQ filters yet.
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post #4 of 6 Old 04-05-2009, 11:48 AM - Thread Starter
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Ok, now we add a little EQ using the REW software and my BFD PEQ.

This is just a touch of EQ at 41hz. I still have more work to do, but the bass of my room is much improved.
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post #5 of 6 Old 04-05-2009, 06:08 PM
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Thats really nice room response. Do you have any photo's of your bass traps and placement of your room?

List your favorite BASS movies here...http://lfemovies.pbworks.com/FrontPage
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post #6 of 6 Old 04-05-2009, 08:37 PM - Thread Starter
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Quote:
Originally Posted by reecew View Post

Thats really nice room response. Do you have any photo's of your bass traps and placement of your room?

No drawings as of yet.

Here is a link to an old review of the HSU TN1220: http://www.stereotimes.com/speak041403a.shtml

The only treatments I have in the HT room right now are some eighthnerve response corner seams and triangles. (http://www.eighthnerve.com/products.html) The eighthnerve stuff are small fabric pads filled with fiberglass. The pads are too small to really serve much purpose at bass frequencies.

In the old 2004 "My Bass Story" 1 thread I did have some of ethan winer's DIY panel traps in my old HT. But those are not setup in the new HT now.

The only bass treatment I can point to is the greenglue double subfloor that is the basement ceiling/living room floor I mentioned in the beginning of this thread. I have approximately 640 sq ft of green glue down above my entire basement. A subset of that space is my hometheater.
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