Jump to content



Sign up for a free account to remove the pop-up ads

Signing up for an account is fast and free. As a member you can join in the conversation, enter contests and remove the pop-up ads that guests get. Click here to create your free account.

Photo
- - - - -

Disappointed- went from sealed to ported (Tempest)


This topic has been archived. This means that you cannot reply to this topic.
32 replies to this topic

#1 of 33 OFFLINE   KyleGS

KyleGS

    Second Unit



  • 342 posts
  • Join Date: Feb 12 2002

Posted July 13 2004 - 02:01 AM

Hey guys-

I went from 122L sealed to 200L (19hz) ported with my Tempest. I'm running a PE250 (no boost).
I heavily braced the new box and used a 6in straight pipe (sched. 40 PVC). I also used about 3 lbs of stuffing.

I listen to alot of music and maybe this wasn't the best idea. The sub seems a great deal slower. The quality of the bass just isn't there anymore.

It does play a lot louder from 25hz and down but I really miss the detail and speed of the sealed box. The two set-ups used the same location, same material, same amp, same everything.

I've eq'ed the sub to knock out any peaks. Even then the sub just sounds slow and bloated in the lower octaves.

Has anyone had similar results when going ported?

I'm now considering just keeping the sealed box and running arounnd 520w of clean power via a Yammie M-85 solid state power amp...or... should I try to tweak the ported design?

#2 of 33 OFFLINE   Darren_T

Darren_T

    Second Unit



  • 494 posts
  • Join Date: Oct 01 2001

Posted July 13 2004 - 02:03 AM

Hi KyleGS,

What was your reason for going with the larger vented alignment? I built the Adire alignment Tempest a while back which is their 214L vented sub. 3lbs of polyfil sounds like way too much but it's been a while, I could be wrong. With the larger vented enclosure you'll get better extension etc... but I don't believe it is a preferred alignment for music only. Mine souded great with music though... was plenty quick but may not be as quick as your sealed enclosure.

#3 of 33 OFFLINE   DanWiggins

DanWiggins

    Second Unit



  • 325 posts
  • Join Date: Aug 15 1999

Posted July 13 2004 - 02:14 AM

Tune lower. Drop your tuning frequency to 15-16 Hz or so. It will help a lot.

My guess is you're now hearing "room boom", the result of a "anechoically flat" speaker loaded in a room. Room gain exaggerates the bottom end of a flat speaker, so you end up with bloated and "slow sounding" bass (yes, for the physicists out there, I know it's not slow - this is when used as a subjective description - please see Tolve and Gabrielsson, JAES).

Tune lower. It will integrate better with the room, and should audibly improve. And you really won't sacrifice any usable output, either.

Dan Wiggins
Adire Audio

#4 of 33 OFFLINE   Cam McFarland

Cam McFarland

    Supporting Actor



  • 698 posts
  • Join Date: Feb 06 2004

Posted July 13 2004 - 03:11 AM

How did you come up with the idea to use a 6" dia. pipe.
My 214l AA Tempest calls for (2) 3" ports. I used no "stuffing", but lined the box with polyfil batting which
I stapled to the interior walls. I also added an extra set of braces to the inside (2 pair of small braces as opposed
to just one).

To my uneducated ear, it sounds great....Posted Image

#5 of 33 OFFLINE   Patrick Sun

Patrick Sun

    Studio Mogul



  • 37,896 posts
  • Join Date: Jun 30 1999

Posted July 13 2004 - 04:02 AM

I used a 6" wide PVC port in my Sunosub II (Tempest, roughly 9 ft^3, tuned to 16Hz). Posted Image
"Jee-sus, it's like Iwo Jima out there" - Roger Sterling on "Mad Men"
Patcave | 2006 Films | 2007 Films | Flickr | Comic-Con 2012 | Dragon*Con 2012

#6 of 33 OFFLINE   dave alan

dave alan

    Second Unit



  • 256 posts
  • Join Date: Aug 30 2002

Posted July 13 2004 - 04:33 AM

IMO, this is the perfect example of a comparison of sealed vs ported.

Same everything (including the room), except for the box type. This is when you can really hear the difference, all computer models, group delay numbers, tuning choices, etc., aside.

You can't factor the sonic sig of the driver in because it's the same driver.

I agree with Dan that modeling a ported sub to play anechoically flat to 20 or less Hz causes huge bloat, in-room, at the bottom end of the music bandwidth.

I also don't care what the physicists say about 'slow' and/or 'fast', or whether or not 20-30 ms is audible.

Low GD + no EQ = less time smear than high group delay + EQ latency/phase shifts. This means that the sealed sub delivers music bandwidth sound to the ear before the ported, EQ'd sub. That would mean the sealed sub is 'faster'. Some prefer the term 'more on-time', but it's saying the same thing...'faster'.

The speed of sound, in your room, is the speed of sound. If the musician is playing in your room, all of the direct radiated sound from each note would arrive at your ear at the same time. The low frequencies wouldn't be delayed 1/3 or more of a second.

To answer the question...yes, I've heard the difference in sound instantly...every time I do the comparisons...all things being equal except for the order and curve of the box. It's the price paid for HT boom.

The answer is a simple one. Use 1 sub for discrete redirected bass and another sub for discrete LFE. Design and tweak the redirected bass sub for best integration and design and crank the LFE sub for the movie sound tracks.

Just an opinion that I've had success with, YMMV.

#7 of 33 OFFLINE   BrianAe

BrianAe

    Second Unit



  • 441 posts
  • Join Date: Dec 02 2002

Posted July 13 2004 - 04:37 AM

Quote:
The answer is a simple one. Use 1 sub for discrete redirected bass and another sub for discrete LFE. Design and tweak the redirected bass sub for best integration and design and crank the LFE sub for the movie sound tracks.


Dave, in one's setup, from a wiring and processor standpoint, how does one accomplish this?

#8 of 33 OFFLINE   KyleGS

KyleGS

    Second Unit



  • 342 posts
  • Join Date: Feb 12 2002

Posted July 13 2004 - 05:29 AM

Well I hate to say that I may be stuck with the 19 hz tuning. My port is on the top of the cabinet with the sub on the bottom. If I make the tube longer it will get too close to the motor structure.
Mr. Wiggins described the sound perfect.
I'm going to try to move the sub out from the corner and take away some of that room gain.
I'll get back with ya'll.

#9 of 33 OFFLINE   Cam McFarland

Cam McFarland

    Supporting Actor



  • 698 posts
  • Join Date: Feb 06 2004

Posted July 13 2004 - 05:52 AM

Quote:
I used a 6" wide PVC port in my Sunosub II (Tempest, roughly 9 ft^3, tuned to 16Hz)



How does this compare to a 200l box....??

#10 of 33 OFFLINE   Cam McFarland

Cam McFarland

    Supporting Actor



  • 698 posts
  • Join Date: Feb 06 2004

Posted July 13 2004 - 05:54 AM

nevermind... 9 cu.ft. is 254l


just a 6" pipe has twice the volume of 2-3" of same length.

#11 of 33 OFFLINE   dave alan

dave alan

    Second Unit



  • 256 posts
  • Join Date: Aug 30 2002

Posted July 13 2004 - 10:13 AM

Dave, in one's setup, from a wiring and processor standpoint, how does one accomplish this?
_______________________________________

You need a player with 6 analog outs.

You need analog bass management, ala the Outlaw ICBM.

1. Run the player's SW out to the LFE sub.

2. Run the ICBM's SW out to the redirected bass sub.

3. Set all speakers 'large' and sub 'yes' in the player.

(Or, you may be lucky enough to have the Lex MC-12 pre that has seperate L and R RB outs and a seperate LFE out...woo-hoo).

The LFE sub will get only LFE and the RB sub will get only RB (because there is no LFE input into the ICBM in the first place).

You'll get the same total output with 2 identical subs as you would with 1 sub that gets the summed signal, but you'll have 5ish dB more headroom in each sub.

If you decide, during movie playback, to switch to the digital input of the pre/pro or receiver, instead of bypass mode, the RB sub will get the summed signal and the LFE sub will act as an LFE boost sub. This will add 6 dB of SPL gain if you feel the need to bleed.

You can select any crossover point for integration of the RB and not affect the LFE signal at all. You'll also have seperate control of the LFE volume and, more importantly, you'll know when there is LFE content.

When switching to CD, the LFE sub will be silent, and when playing MC SACD and DVD-A, you can add as little or as much .1, or even switch the LFE sub off altogether.

This way, you have the best of both worlds and switching from movies to music requires no tweaking.

Hope this helps.

#12 of 33 OFFLINE   Pete Mazz

Pete Mazz

    Supporting Actor



  • 761 posts
  • Join Date: May 17 2000

Posted July 13 2004 - 11:15 AM

I feel the same way about ported subs, or speakers for that matter. They just don't have that clean sound that I prefer.

And by the time you tune really low, you lose a lot of the additional output of the port, so why bother.

Pete

#13 of 33 OFFLINE   Brian Bunge

Brian Bunge

    Producer



  • 3,719 posts
  • Join Date: Sep 11 2000

Posted July 13 2004 - 12:50 PM

Kyle,

Try adding another 1b. of polyfill. Hank Frankenberg build a Tempest is 175L tuned to 17.5Hz and used 64oz. (4 lbs.) of polyfill. This should effectively lower the tuning frequency a bit. I'm not totally sure how much, but probably a couple Hz.

Also, I built a similar sub for my father using the PE DVC 15". Sounds great to me! Posted Image
Brian Bunge
RAD Home Theater

#14 of 33 OFFLINE   Aaron Gilbert

Aaron Gilbert

    Second Unit



  • 319 posts
  • Join Date: Sep 17 2003

Posted July 13 2004 - 01:26 PM

I'm with Dan, I bet this is a result of room gain added to a subwoofer that is anechoically flat into the low 20's (-3dB point looks to be right at 20Hz). I have my subwoofer tuned to 11Hz, and aside from extension below 20Hz, I can't tell the vented version apart from the sealed.

Also, I ran into a situation with my last subwoofer in an apartment, where it sounded absolutely horrible. This was a sealed isobaric subwoofer (push-pull, of course) that had sounded great in larger rooms. F3 was in the low 30's. In the apartment though, room gain contributed to make it sound slow and boomy, at least in a corner. Different placement, such as in the center of the room, might have helped, but that was not an option, unfortunately.

So certainly don't forget to remember that room dimensions can play a huge part in the overall frequency response and quality of sound. The great thing about DIY is that you can adjust/remove the port to best fit your needs. Try asking the salesman at your local store how much they'd charge to adjust the port in that latest and greatest subwoofer you purchased, to best fit the gain in your room. Posted Image

Cheers,

Aaron Gilbert

#15 of 33 OFFLINE   Patrick Sun

Patrick Sun

    Studio Mogul



  • 37,896 posts
  • Join Date: Jun 30 1999

Posted July 13 2004 - 03:00 PM

Quote:
just a 6" pipe has twice the volume of 2-3" of same length.


Not true, two 3" wide ports yield roughly the same surface area as a 4.24" wide port, not a 6" wide port.
"Jee-sus, it's like Iwo Jima out there" - Roger Sterling on "Mad Men"
Patcave | 2006 Films | 2007 Films | Flickr | Comic-Con 2012 | Dragon*Con 2012

#16 of 33 OFFLINE   Greg Monfort

Greg Monfort

    Supporting Actor



  • 884 posts
  • Join Date: May 30 2000

Posted July 13 2004 - 03:35 PM

KyleGS/BB,

There's much more damping/lowering of Fb to be gained by stuffing the vent to make it more aperiodic than increasing the cab's stuffing. If there's considerable output around/at Fb, then a screen will be required to keep the stuffing from being pumped out.

Pete,

If you don't use speakers, how are you reproducing the LF/sub BW to get a clean sound? WRT low tuned EBS alignments, I consider any acoustic gain as good, so that's why me and many others bother. The more extreme among us build huge basshorn systems to narrow the gap between 'live' and Memorex. Posted Image

GM
Loud Is Beautiful, If It's Clean

#17 of 33 OFFLINE   Paul Spencer

Paul Spencer

    Stunt Coordinator



  • 159 posts
  • Join Date: Sep 15 2003

Posted July 13 2004 - 11:28 PM

Kyle,

Perhaps you should look at doing some in room measurements. This might help. Then again, if vented doesn't work for you, why persist with it?

I have two subs and I have compared vented vs sealed and my first reaction was that there was very little difference for music - no major difference in SPL or extension or quality either for that matter. Both were in a 70L box, vented Fb @ 18 Hz. I have also noticed in my simulations that in the range commmonly covered by music, there is barely a JND (just noticeable difference) in extension. +6db @ 25 Hz probably won't help you much for music! Maybe you should revert back to sealed!

Another route is TL. Then you get the best of both sealed and vented (extension of vented, yet more refined) and some more ... better transient response - I believe a vented box is just about the worst commonly used alignment for transient response, while TL's are far better. For HT this can lead to LFE overexcursion, but for music this shouldn't be a problem. When people talk about subjective "speed" then I wonder if transient response is a part of what they are hearing.

Audio Website | Audio blog Open baffle & Omni speakers, TLs, servo subs and more

My work: http://www.redspade.com.au/
Red Spade - creative web design studio

#18 of 33 OFFLINE   Cam McFarland

Cam McFarland

    Supporting Actor



  • 698 posts
  • Join Date: Feb 06 2004

Posted July 14 2004 - 02:18 AM

Quote:
Not true, two 3" wide ports yield roughly the same surface area as a 4.24" wide port, not a 6" wide port.




Patrick...reread my post.....Posted Image

I dont say it is equal....I said a 6" port has TWICE the volume of 2 - 3" ports.

Pretty close to what you are stating, I think....Posted Image

#19 of 33 OFFLINE   Seth_L

Seth_L

    Screenwriter



  • 1,553 posts
  • Join Date: Apr 05 2002

Posted July 14 2004 - 02:40 AM

A large part of your problem is likely that the bass coming from the speaker is not in phase with the rest of your system anymore.

Set the phase on the amp to 0 (if you have that adjustment). Play a test tone that is 1 octave below your crossover point of your front speakers(40Hz for an 80Hz setting). Increase the distance setting for you sub in your reciever until you get max SPL at your seat (use a meter and your ear). Now your sub will be in phase with your mains. It should sound quite a bit better.

#20 of 33 OFFLINE   DanWiggins

DanWiggins

    Second Unit



  • 325 posts
  • Join Date: Aug 15 1999

Posted July 14 2004 - 02:46 AM

Kyle,

Get an elbow - you can bend the port around, if needed.

Greg,

Don't tell them about the screen over the port - let them experience the Cannon of Polyfill at least once! Posted Image

Dan Wiggins
Adire Audio


Back to Members' Theaters, HT Projects, Remotes, Seating, Accessories & Lighting



Forum Nav Content I Follow