Down firing HSU VTF-15 success! - AVS Forum
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post #1 of 17 Old 12-29-2012, 11:02 AM - Thread Starter
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I have had my VTF-15 in a down firing position for about 2 months already and it smoothed out ALL of the ear pressure i was getting at high levels when watching movies after calibrating with Audyssey. I like the down firing position so much better that i have not moved it for the last two months and it is staying there!

In my 17x24 theater the improvements are...

ALL ear pressure during movies and music is gone
Even MORE feel since all of the pressure waves are hitting the floor!!!
The bass is tighter even in Q 0,7...which is nice.
Hits harder and deeper than before.

I think that the reason i was getting the ear pressure with the regular recomended settings for the VTF-15 is that my theater is all solid wood including ceiling and floor....no leakage...maybe just too much energy being fired at the center of the room. This may not be your cup of tea...but in my room i am a down firing subwoofer guy for sure!!!

Btw..before this i also tinkered with lying the sub side ways and spinning the sub in all directions with the driver facing away etc. Hands down the BEST way was the down firing position...it just hits SO much harder with no ear pressure at all. And oh yea, i also tried it with the driver facing the ceiling...not so good biggrin.gif

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post #2 of 17 Old 12-29-2012, 11:56 AM
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Glad it worked out for you, but isn't it kind of ugly having the amp plate on the top?
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post #3 of 17 Old 12-29-2012, 12:40 PM - Thread Starter
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You really can't see the sub as my theater is all black and light controlled. I also did not like seeing that gigantic 15 inch driver and front grille. I painted my front speakers black too so they also "disappear" and blend in.
I have had more than one person ask me "where is all of that sound comming from?". I then tell them "look closer" and proceed to raise the house lights with my remote. wink.gif All of a sudden they see two 50 inch towers hung up on the wall on both sides of the projection screen right in front of their faces along with a center channel. When watching a movie in total darkness or even with moderate light all you should see is the movie/screen not the speakers or the audio equipment lights!

Once you go BLACK you NEVER go back! ha ha ha wink.gif

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post #4 of 17 Old 12-29-2012, 04:46 PM
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I would love to see pics of this setup. Also is it true that some sub drivers are not meant to be used in a downfiring configuration due to extra stress when firing downward? I was told this one time when dealing with Parts Express.
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post #5 of 17 Old 12-29-2012, 06:23 PM
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Quote:
Originally Posted by matrixj3 View Post

I have had my VTF-15 in a down firing position for about 2 months already and it smoothed out ALL of the ear pressure i was getting at high levels when watching movies after calibrating with Audyssey. I like the down firing position so much better that i have not moved it for the last two months and it is staying there!

In my 17x24 theater the improvements are...

ALL ear pressure during movies and music is gone
Even MORE feel since all of the pressure waves are hitting the floor!!!
The bass is tighter even in Q 0,7...which is nice.
Hits harder and deeper than before.

I think that the reason i was getting the ear pressure with the regular recomended settings for the VTF-15 is that my theater is all solid wood including ceiling and floor....no leakage...maybe just too much energy being fired at the center of the room. This may not be your cup of tea...but in my room i am a down firing subwoofer guy for sure!!!

Btw..before this i also tinkered with lying the sub side ways and spinning the sub in all directions with the driver facing away etc. Hands down the BEST way was the down firing position...it just hits SO much harder with no ear pressure at all. And oh yea, i also tried it with the driver facing the ceiling...not so good biggrin.gif

You placed the sub cone down into your floor so that the driver is beating on the floor? What made you think this was a good idea? You didn't change how 'deep' the sub goes nor any other sub characteristic. At best you tried to "muffle", or rather 'hamstring" your sub.
rolleyes.gif
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post #6 of 17 Old 12-29-2012, 06:54 PM
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Originally Posted by sputter1 View Post

You placed the sub cone down into your floor so that the driver is beating on the floor? What made you think this was a good idea? You didn't change how 'deep' the sub goes nor any other sub characteristic. At best you tried to "muffle", or rather 'hamstring" your sub.
rolleyes.gif

My thinking exactly.

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post #7 of 17 Old 12-29-2012, 07:05 PM
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Originally Posted by sputter1 View Post

You placed the sub cone down into your floor so that the driver is beating on the floor? What made you think this was a good idea?
I assume he put it on legs.
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You didn't change how 'deep' the sub goes nor any other sub characteristic.
Yes, he did. Downward firing adds acoustic loading, lowering response a few Hz, while THD is reduced, as above bandwidth harmonics are acoustically filtered by down-firing. This results in cleaner sound at high volume, which I believe is what he means by reduced 'ear pressure'. The lowered response isn't enough to really make that much difference, but the filtering of above bandwidth harmonics also subjectively makes a sub seem to go lower. All things considered downward and rearward firing subs work better than front firing, but they don't sell as well, as the average buyer thinks you have to see the cone to hear sound coming from it. That is true only above about 300Hz.
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Also is it true that some sub drivers are not meant to be used in a downfiring configuration due to extra stress when firing downward?
There is no extra stress. Some drivers have a combination of cone mass and suspension stiffness that might result in sag, leading to non-linearity.

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post #8 of 17 Old 12-29-2012, 07:31 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Quote:
Originally Posted by sputter1 View Post

You placed the sub cone down into your floor so that the driver is beating on the floor? What made you think this was a good idea?
I assume he put it on legs.
Quote:
You didn't change how 'deep' the sub goes nor any other sub characteristic.
Yes, he did. Downward firing adds acoustic loading, lowering response a few Hz, while THD is reduced, as above bandwidth harmonics are acoustically filtered by down-firing. This results in cleaner sound at high volume, which I believe is what he means by reduced 'ear pressure'. The lowered response isn't enough to really make that much difference, but the filtering of above bandwidth harmonics also subjectively makes a sub seem to go lower. All things considered downward and rearward firing subs work better than front firing, but they don't sell as well, as the average buyer thinks you have to see the cone to hear sound coming from it. That is true only above about 300Hz.
Quote:
Also is it true that some sub drivers are not meant to be used in a downfiring configuration due to extra stress when firing downward?
There is no extra stress. Some drivers have a combination of cone mass and suspension stiffness that might result in sag, leading to non-linearity.

Pointing at the floor or corner loading same diff. You're only getting some boundry gain. I'm not seeing the advantage pointing at the floor vs a wall. Only seems to go lower is my point. Again, filtered by the floor or wall i'm still not seeing a difference.
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post #9 of 17 Old 12-29-2012, 07:56 PM
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I know there are all sorts of scientic reasons why down firing subs may work better but frankly, i've never seen one that looks as sexy as most front firing subs. I tend to have my speaker covers off in my home theater.

Projector: Benq W1070 1080p 2D/3D
Screen: 120" Elite fixed frame
AVR: Onkyo TX-NR809
Mains: Klipsch RF-62ii x 2
Center: Klipsch RC-62ii
Surrounds: Klipsch RS-42ii x 2
Subs: Dual Hsu VTF-15H's
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post #10 of 17 Old 12-30-2012, 04:06 AM - Thread Starter
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Quote:
Originally Posted by Bill Fitzmaurice View Post

I assume he put it on legs. Yes, he did. Downward firing adds acoustic loading, lowering response a few Hz, while THD is reduced, as above bandwidth harmonics are acoustically filtered by down-firing. This results in cleaner sound at high volume, which I believe is what he means by reduced 'ear pressure'. The lowered response isn't enough to really make that much difference, but the filtering of above bandwidth harmonics also subjectively makes a sub seem to go lower. All things considered downward and rearward firing subs work better than front firing, but they don't sell as well, as the average buyer thinks you have to see the cone to hear sound coming from it. That is true only above about 300Hz.
There is no extra stress. Some drivers have a combination of cone mass and suspension stiffness that might result in sag, leading to non-linearity.

Hey Bill! You are REALLY Yoda! You assumed right with the responses...and it seems you have done alot of tinkering with audio equipment and speakers. Btw do you remember the "speaker suspenders" they used to make in 70's? I made some a while back and i made some for subs too just to see if a sub hung up on a ceiling would sound different or even better and the answer is YES! The only thing is that you would need a fairly high ceiling or place the sub high above and or in front of the listening area. Imagine 2 submersives hung up on the ceiling taking up ZERO floor space!eek.gif They end up looking a lot like the PA monitors you see hanging at churches and concerts. But if you have a dedicated theater that is black, then they also would blend in without being noticed that much. The trade off is worth it imo. I used to hang the old monster CRT projectors and know how to reinforce a ceiling properly to hang audio and video equipment. In fact i used to sleep right under 150 lb. projector for about 10 years until the lightweights came in to take their place to retire them. Every night i when i was lying in bed i would look straight up at that 30 x 25 block of metal and say to myself "trust in your work". eek.gif And after a prayer...i would then go to sleep! smile.gif

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post #11 of 17 Old 12-30-2012, 05:46 AM
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Originally Posted by sputter1 View Post

Pointing at the floor or corner loading same diff. You're only getting some boundry gain.
No, you're getting a measure of bandpass loading. That has nothing to do with pi space loading.
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Again, filtered by the floor or wall i'm still not seeing a difference.
Measure the response in both positions and you will see the difference, on your SPL chart. You'll hear a difference too.
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it seems you have done alot of tinkering with audio equipment and speakers.
I got past the tinkering stage in 1970, when I started studying acoustical engineering. That's when I began experimenting, which is what you call educated tinkering. cool.gif

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post #12 of 17 Old 12-30-2012, 07:34 AM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Quote:
Originally Posted by sputter1 View Post

Pointing at the floor or corner loading same diff. You're only getting some boundry gain.
No, you're getting a measure of bandpass loading. That has nothing to do with pi space loading.
Quote:
Again, filtered by the floor or wall i'm still not seeing a difference.
Measure the response in both positions and you will see the difference, on your SPL chart. You'll hear a difference too.
Quote:
it seems you have done alot of tinkering with audio equipment and speakers.
I got past the tinkering stage in 1970, when I started studying acoustical engineering. That's when I began experimenting, which is what you call educated tinkering. cool.gif

That won't be hard to test with sweeps though I doubt very much that i'll see anything lower than the 13hz I hit currently. A spl meter won't help in this respect, i'll be running sweeps with REW to verify.
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post #13 of 17 Old 12-30-2012, 04:07 PM
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Bill, is it going to produce more spl and the least amount of THD to have the ports downfiring and the driver front firing, both downfiring, or vice-versa?

This is interesting.

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post #14 of 17 Old 12-30-2012, 05:28 PM
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Bill, is it going to produce more spl and the least amount of THD to have the ports downfiring and the driver front firing, both downfiring, or vice-versa?
The direction the port faces has no effect on THD, as ports don't pass harmonics. If the port is down or rear firing its tuning frequency can be lowered if it's close enough to the floor or wall. That may or may not make the sub work better. If you have measuring gear you can easily see what happens by varying the spacing to the wall and/or floor, varying that distance to fine tune the result.

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post #15 of 17 Old 12-30-2012, 06:17 PM
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Originally Posted by Bill Fitzmaurice View Post

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Originally Posted by BufordTJustice View Post

Bill, is it going to produce more spl and the least amount of THD to have the ports downfiring and the driver front firing, both downfiring, or vice-versa?
The direction the port faces has no effect on THD, as ports don't pass harmonics. If the port is down or rear firing its tuning frequency can be lowered if it's close enough to the floor or wall. That may or may not make the sub work better. If you have measuring gear you can easily see what happens by varying the spacing to the wall and/or floor, varying that distance to fine tune the result.

I stated that, facing the wall or floor is the same diff.
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post #16 of 17 Old 12-30-2012, 10:42 PM
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Originally Posted by Bill Fitzmaurice View Post

The direction the port faces has no effect on THD, as ports don't pass harmonics. If the port is down or rear firing its tuning frequency can be lowered if it's close enough to the floor or wall. That may or may not make the sub work better. If you have measuring gear you can easily see what happens by varying the spacing to the wall and/or floor, varying that distance to fine tune the result.

Thanks for your reply, Bill.

So, if I'm understanding this correctly, the band-pass loading on the port created by its proximity to the wall or floor can act as a pseudo port extension?

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post #17 of 17 Old 12-31-2012, 07:07 AM
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Originally Posted by BufordTJustice View Post

Thanks for your reply, Bill.
So, if I'm understanding this correctly, the band-pass loading on the port created by its proximity to the wall or floor can act as a pseudo port extension?
+1. In the same fashion when the driver is facing the wall or floor the space between the driver and the boundary acts as an extension of the cabinet, turning a reflex or sealed cab into a bandpass. The tuning of the bandpass is accomplished by varying the distance to the boundary. With downfiring you have two tuning methods, the height of the feet and the distance to the wall; both will affect the result. Trying to tune by ear isn't easy, but it also isn't impossible, as witnessed by the OPs result. It's a simple affair if you have measuring gear. The closer to the boundary the greater the loading effect, but if you go too close you'll end up worse off.

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