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post #91 of 127 Old 09-28-2003, 03:46 PM - Thread Starter
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O.K. O.K., my old Rane PE-17 did not have markings on the knobs for the various frequencies (long story). You forgot to mention the drops of nail polish I used to hold the knobs to their proper settings!

Mark, you know I had to make even more of a challenge for you. It is amazing you got things set as well as you did, considering the EQ I provided you with!

No wonder the QSC DSP-IV was recommended as a replacement, no knobs at all to play with ;), just a computer cable to plug in.

Mark, The Titan AE is THE demo disc for these subs. It was simply amazing. Wish you were here last night. Hope all is well.

My Home Theater of the Month- Le Petit Trianon

There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #92 of 127 Old 09-28-2003, 04:30 PM
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10Hz. That is low.

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post #93 of 127 Old 09-28-2003, 05:14 PM
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Quote:
Originally posted by mendes9
Why do you post your web site address? If you click on current or future components you deny access, error? If not what's the point?
Just to let you know you're not worthy. Seriously though, I have often wondered the same thing.
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post #94 of 127 Old 09-28-2003, 05:29 PM
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ha ha.. ha.. ahh let's not Kill a great thread... :D

Save Your Frequent Flyer Miles !! Barber's jobs are also being exported to China, you will have to fly to China now for a hair cut.
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post #95 of 127 Old 09-28-2003, 05:29 PM
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Edit: damn, I've got a worthy opponent here :D.

(no, I'm not talking to myselves people - someone is deleting their posts).

We were posting at the same time - agreed - truce.
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post #96 of 127 Old 09-28-2003, 05:42 PM
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Here's the almost latest in room FR plot for Jeff's 2 B-DEAP's. Almost because the 70Hz rise in response was taken care of in a subsequent QSC filter update. Since this plot was made using Jeff's whole audio chain (processor, equalizer, and power amp) the plot reflects the extreme low frequency roll off in the K2 that Mark Seaton mentioned, above. Again note the left end of the x-axis starts at 10Hz.

http://www.cmcpics.homestead.com/bdeapwithqsc.jpg
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post #97 of 127 Old 09-28-2003, 06:13 PM - Thread Starter
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Chris,

Since it seems the amp is sharply rolling off at 10 hz, how would a second K2 affect the graph (running two bridged K2s). One into each sub??

And can you better explain 'headroom'?

Thanks!

My Home Theater of the Month- Le Petit Trianon

There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #98 of 127 Old 09-28-2003, 07:01 PM
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A second K2 wouldn't really affect this frequency response graph. Headroom in rerms of amplification is the amount of power available to go louder (more power) without reaching the amps limits, dynamic headroom is similar, but refers to an amplifiers ability to output more power than its RMS capacity for short periods (transients).

By way of example, if your amplifer is a 100Wpc RMS model, this represents 20dBW of gain, if you are playing the amplifier at 50Wpc RMS (17dBW gain) you have 3dB of headroom left in the amplifier. Doubling the power from 50 to 100Wpc gives you and additional gain of 3dB.

In your situation, a K2 in stereo has 800Wpc into 4 ohms, which represents a gain of 29dBW (gain referenced to 1 Watt), a K2 in bridged mono mode produce 2,500Wpc into a 4 ohm load, for a gain of 34dBW. Comparing the gain figures (34dBW-29dBW=5dBW) we can see that adding a second K2 and bridging both will give 5dB of additional headroom. Certainly a very noticeable amount.

The low frequency response of the K2 is band limited with an 8 Hz double integrated 3rd-order Butterworth high-pass filter, which matches with what Mark mentioned above and the FR plot shows.
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post #99 of 127 Old 09-28-2003, 07:01 PM
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Thanks for letting us in last night Jeff:D When I was feeling my hair moving I would guess that we were moving a lot of air in that room. Limbo rock comes to mind.....how low can you go. I was throwing out all sorts of compliments peppered with a nice share of using the lords name in vain and such but no one could hear me. Great time indeed !:D

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post #100 of 127 Old 09-28-2003, 11:43 PM
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Sorry Father, but this WAS funny from Art: "I was throwing out all sorts of compliments peppered with a nice share of using the lords name in vain and such but no one could hear me" :)

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post #101 of 127 Old 10-27-2003, 06:50 PM - Thread Starter
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Quote:
Originally posted by MYSPHYT (Chris Collins)
A second K2 wouldn't really affect this frequency response graph. Headroom in rerms of amplification is the amount of power available to go louder (more power) without reaching the amps limits, dynamic headroom is similar, but refers to an amplifiers ability to output more power than its RMS capacity for short periods (transients).

By way of example, if your amplifer is a 100Wpc RMS model, this represents 20dBW of gain, if you are playing the amplifier at 50Wpc RMS (17dBW gain) you have 3dB of headroom left in the amplifier. Doubling the power from 50 to 100Wpc gives you and additional gain of 3dB.

In your situation, a K2 in stereo has 800Wpc into 4 ohms, which represents a gain of 29dBW (gain referenced to 1 Watt), a K2 in bridged mono mode produce 2,500Wpc into a 4 ohm load, for a gain of 34dBW. Comparing the gain figures (34dBW-29dBW=5dBW) we can see that adding a second K2 and bridging both will give 5dB of additional headroom. Certainly a very noticeable amount.
Chris (Michigan's resident calibration / installer expert) is coming over this Wednesday to install a second K-2. For a promised 5 additional db of headroom, I'm sold!

Chris will run some more room analysis and bass response tests and we'll post what we find.

Looking forward to a more mind-numbing bass.

Watch the thread for more details!

My Home Theater of the Month- Le Petit Trianon

There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #102 of 127 Old 10-27-2003, 07:25 PM
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Are you kidding me????!!!!! What do you expect to keep your house upright? Bass waves?

What will your neighbors say (the ones in Ohio)?

By the way, what does "Trionon" mean? Remaining budget?

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post #103 of 127 Old 10-28-2003, 05:29 AM
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Quote:
Originally posted by thebland
Chris (Michigan's resident calibration / installer expert) is coming over this Wednesday to install a second K-2. For a promised 5 additional db of headroom, I'm sold!

Chris will run some more room analysis and bass response tests and we'll post what we find.

Looking forward to a more mind-numbing bass.

Watch the thread for more details!
VERY cool, Jeff! I am a huge believer in POWER - 'specially for subs. I upgraded from a 1kw Samson for my pair of SVS Ultras to a Crown K2 for them. I really don't know what improvement in max SPL's that gave me, but yeah, the SLAM is happening. Forget RMS. Peak current is where the IMPACT is! Heck yeah!! :D
Looking forward to your report.

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post #104 of 127 Old 10-28-2003, 09:47 AM
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Quote:
Originally posted by thebland
Chris (Michigan's resident calibration / installer expert) is coming over this Wednesday to install a second K-2. For a promised 5 additional db of headroom, I'm sold!

Looking forward to a more mind-numbing bass.
Nice to hear about this development Jeff,

Indeed, you will increase overall headroom by about 5dB. It should be noted that you should take a look at the power available for these amplifiers from the wall, as that becomes the bottleneck in the system. While if we went off of max power you would think of needing a 20A circuit for each, in reality, a single 20A for the pair of amplifiers is about perfect. Most important is to be sure the power draw from these amplifiers won't adversely affect the rest of your system. What you do have going for you is that the K2 amplifier is ~92% efficient, which means it draws at most 1/2 the power as a more conventional amplifier would while delivering the similar power. You do want to be somewhat aware of overzealous boost at the very low end, as you have enough power to get closer to trouble. That said, IMO, a bridged K2 is my preferred amplifier for the B-DEAP 32 in a HT. Headroom is a beautiful thing!

Sounds like it's nearing time to find something which will better compliment the headroom of the subs over the rest of the bandwidth.

I don't recall how you had your Citation amplifiers connected. How much power did you have for each front channel at 4 Ohms?

I'm almost jealous. :cool:

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post #105 of 127 Old 10-28-2003, 10:00 AM - Thread Starter
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Mark,

My Citations deliver 150W at 8 ohms and approx 275 watts into 4 ohms.

Power wise, I do have an available 20 AMP circuit that I will use.

Explain this: You do want to be somewhat aware of overzealous boost at the very low end, as you have enough power to get closer to trouble.

Do you mean overloading the subs, pushing the amps or my hearing??

Thanks!!!

My Home Theater of the Month- Le Petit Trianon

There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #106 of 127 Old 10-28-2003, 11:19 AM
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Quote:
Originally posted by thebland

Power wise, I do have an available 20 AMP circuit that I will use.

Explain this: You do want to be somewhat aware of overzealous boost at the very low end, as you have enough power to get closer to trouble.

Do you mean overloading the subs, pushing the amps or my hearing??

Thanks!!!
I think Mark is concerned about the travel and power limits of the speakers, 2.5KW is a lot of power. Mark can confirm, the B-DEAP's drivers just idle along down to 30Hz or so with the loading of the horns keeping everything in check, below 30Hz there is less horn loading and the drivers start moving closer towards Xmax to reproduce these frequencies.

Right now your subs have a 3-5 dB peak at 25Hz rolling off to a flat response on either side. I don't anticipate changing this.

Mark, do you suggest filtering below 20Hz? Right now the only subsonic filtering is the 8 Hz high pass filter in the K2's.
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post #107 of 127 Old 11-01-2003, 11:18 PM
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Jeff and I installed an additional K2 amplifier to drive the SPL B-DEAP-32's. One amp per sub, bridged mono and biwired delivering 2.5KW RMS per sub.

http://www.cmcpics.homestead.com/fil.../crown_k2s.jpg

We started off by measuring how the subs performed with the equalizer bypassed, here's the resulting frequency response plot.

http://www.cmcpics.homestead.com/fil..._sub_no_eq.jpg

The response is dominated by a ~33Hz peak, which happens to coincide with a first order room width mode and is very close to a second order room length mode. Our listening test confirmed this, a massive boom in the 30 Hz region.

The next plot is the frequency response of the system with equalization applied. Much smoother, within +/-3dB throughout the spectrum. Subs cross over to the mains at 90 Hz. Notice that the low frequency on this plot is 10Hz, not 20Hz and that the response is only down about 4dB at 10Hz. The 5dB bump at ~25Hz is intentional, gives the listening experience an extra tactile dimension without muddying the sound.

http://www.cmcpics.homestead.com/fil...b_after_eq.jpg

The equalization curve applied to go from the first curve to the second can be seen here.

The extra headroom afforded by the amplifier addition plus the additional time spent tuning the equalization has improved the transient response of the system and given the bass that tight edge that runs up your spine and scares you if you're not prepared for it.
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post #108 of 127 Old 11-02-2003, 06:12 AM
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Beautiful curves, Chris! Fantastic what it did at the 10hz range!!

Quote:
The extra headroom afforded by the amplifier addition plus the additional time spent tuning the equalization has improved the transient response of the system and given the bass that tight edge that runs up your spine and scares you if you're not prepared for it.
Oh, Yeah!! Very cool!

Gordon
Getting ready to dust off my BFD.
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post #109 of 127 Old 11-02-2003, 07:23 AM
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heh. madness. :)

but what about the 2nd K2? Is there a measurable difference?

You might want to have your foundation earthquake treated with some side reinforcement :)...
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post #110 of 127 Old 11-02-2003, 08:06 AM
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Quote:
Originally posted by CanO
heh. madness. :)

but what about the 2nd K2? Is there a measurable difference?

We tried to measure the peak curve using actual SPL's, but unfortunately my calibrated microphone does not handle levels above 110dB SPL well, distortion takes over.

The main difference is not in absolute loudness, (the subs were already a match for the mains in SPL's), but in faster, sharper transients and that "no limits" sound you get when you have appropriate headroom.
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post #111 of 127 Old 11-02-2003, 08:33 AM
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Quote:
Originally posted by mysphyt

The extra headroom afforded by the amplifier addition plus the additional time spent tuning the equalization has improved the transient response of the system and given the bass that tight edge that runs up your spine and scares you if you're not prepared for it.
The first curve looks like pretty standard stuff. But.......that second curve is just plain impressive! With my B4s coming, I was planning on using my Krell Theater Amp Standards, but after seeing these curves, I don't know....I may look more seriously at the Crowns. Okay....2 obvious questions: How did you use the EQ to kill that 30 Hz bump......and also, please discuss the difference in that magnificent swing in 10 Hz performance. Is 94 dB your zero point reference? And....are you using a BFD?....if not, then what?
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post #112 of 127 Old 11-02-2003, 08:58 AM
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Quote:
Originally posted by mysphyt

The main difference is not in absolute loudness, (the subs were already a match for the mains in SPL's), but in faster, sharper transients and that "no limits" sound you get when you have appropriate headroom.
Yes! Yes! Now that's what I'm talking about! I had a tough time selling my need to upgrade from 1kw to 2kw on my subs to some very knowlegable folks. I'm sure they still think I'm nuts. :) Well, they may be right, but I believe I can hear a difference and feel a difference when over-amping. I'm not talking about SPL's on test tones. Got more of them than I need. I'm talking about the impact of sudden transients. These big drivers need lots of inrush current. You won't get that from an amp whose peak rating is close to it's RMS rating which is at or below the driver's RMS power rating. (< try and figure that convoluted statement!)

That Bdeap setup must be AWESOME!! Very cool.

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post #113 of 127 Old 11-02-2003, 11:06 AM
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Quote:
Originally posted by Gordon Groff
Yes! Yes! Now that's what I'm talking about! You won't get that from an amp whose peak rating is close to it's RMS rating which is at or below the driver's RMS power rating. (< try and figure that convoluted statement!)
Gordon

now calm down Gordon....next thing you know, you'll be out buying 2 more Ultras for the other corner:p

On another note, I wonder what the dip at 64 Hz is all about. He must have a 16 foot dimension in his room somewhere. Either front to back or side to side. Of course, it could be intentionally induced through the EQ, I guess. Be neat to know why though.
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post #114 of 127 Old 11-02-2003, 01:43 PM
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Quote:
Originally posted by javry
The first curve looks like pretty standard stuff. But.......that second curve is just plain impressive! With my B4s coming, I was planning on using my Krell Theater Amp Standards, but after seeing these curves, I don't know....I may look more seriously at the Crowns. Okay....2 obvious questions: How did you use the EQ to kill that 30 Hz bump......and also, please discuss the difference in that magnificent swing in 10 Hz performance. Is 94 dB your zero point reference? And....are you using a BFD?....if not, then what?
Javry
The subs were equalized using a QSC DSP-4 processor, the actual equalization curve applied is linked in the post above.

Our first objective in equalizing the subs was to ensure that the crossover to the mains was smooth, then we worked to flatten the overall LFE response, then add in the 25Hz "kick". Since these subs are extremenly efficient, the equalizer carves away the peaks to bring things in line without sacrificing overall system SPLs. Thanks to Mark Seaton from SPL/Servo-Drive for his expert advice on taming these subs.


Quote:
On another note, I wonder what the dip at 64 Hz is all about. He must have a 16 foot dimension in his room somewhere. Either front to back or side to side. Of course, it could be intentionally induced through the EQ, I guess. Be neat to know why though.
Jeff's room is 17 wide, the ~60 Hz dip is modal. You can see it in the unequalized response also.
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post #115 of 127 Old 11-03-2003, 05:20 AM - Thread Starter
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Chris really did a number on the subs..Very pleased. Before Chris worked in my room, it never sounded like it does now. Here is my plug for a pro to come in and tune the room. It really allows one to get the most out of the equipment that ythey've purchased. Particulalry if you have a penchant for the low, low bass and a flat response.

The subs represent limitless, powerful bass that can handle any soundtrak at reference (and above) with aplomb.

Unfortunately, it has made cause for me to re-examine my mains as they are not able to keep up with the subs at the highest levels (I guess a nice problem to have ;).

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There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #116 of 127 Old 11-04-2003, 04:17 PM
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Indeed calibration is critical to make the best use of your components' capability. Fortunately the popularity of video test equipment has greatly increased the awareness of testing in general, including audio. Subwoofers are the easiest to understand what you can and cannot fix. It should be re-iterated that EQ is not a silver bullet, but rather a means to apply contouring of the response and to better hide remaining problems.

With all this talk of Equalization and calibration, some might find a post I made recently to the Chicagoland board of interest:
Subwoofer Equalization Discussion

I personally expect measurement and DSP filtering to see much higher useage in future home theaters. There are still many ways in which we can better set up our home theaters through careful measurement and adjustments which are currently lumped into bass management. While not the ideal location in which I'd prefer to do things, I have been looking at some professional 8x8 DSP processors to handle all bass management, arrival alignment and EQ in a single box. Some examples of such units are the Rane RPM88 and the BSS sw3088 SoundWeb Lite. Similarly 4x4 units like the Rane RPM44 could be used for the LCR & Subwoofer very effectively. There are a handful of other makers of such products as well.

I should really start a thread on what is effectively DIY bass management in these DSP processors.

Nice to hear you are enjoying your theater Jeff, I will have to come out and experience it again in the near future.

Best Regards,

Mark Seaton
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post #117 of 127 Old 02-03-2004, 06:40 PM
 
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What a project ! I no longer feel like a pig for putting two pb=2 + into a 5700^3 foot room...:p

I am meeting with my brother and his partner on Wednsday, February 4... We are talking about subs... They build pro-audio gear now... and are thinking about doing custom home theatre subs...

They are also handling the "measuring" portion of the SVS Vs. Hsu shootout...

I will keep you posted...

I read fairly quickly through the posts here... is there one place that had the max SPL's at various frequencies ?
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post #118 of 127 Old 02-04-2004, 06:00 AM - Thread Starter
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Perhaps I can get Chris to comment as he has all the data on the subs.

You can never be too much of a 'pig' in the bass dept.

Mark Seaton is the bass head of all bass heads around here....

THe Servodrive equipment I am using is rooted in pro gear...Very neat stuff.

My Home Theater of the Month- Le Petit Trianon

There are more than a handful of [op amps] that sound so good that most designers want to be using them as opposed to discreet transistors. Dave Reich, Theta 2009
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post #119 of 127 Old 02-04-2004, 07:09 AM
 
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It would be interesting to see... How is the room now ? It looks great !
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post #120 of 127 Old 02-04-2004, 08:27 AM
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Quote:
Originally posted by craigsub
I read fairly quickly through the posts here... is there one place that had the max SPL's at various frequencies ?
Most of the curves posted above are normalized to 100dB. There aren't any max SPL curves posted due to the limitations of the measurement system used. The mics used do not respond accurately at very high SPL levels.

I have some additional equipment now that can measure higher SPL levels accurately, so we should be able to get this data.
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Closed Thread Subwoofers, Bass, and Transducers

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