DIY Subwoofer considerations - Page 2 - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 2Likes
Reply
 
Thread Tools
post #31 of 41 Old 01-14-2020, 11:25 AM - Thread Starter
5js
Member
 
5js's Avatar
 
Join Date: Mar 2012
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 10
Quote:
Originally Posted by Augerhandle View Post
Were your other speakers disconnected?
no. All speaker were physically connected to the AVR.

REC: Onkyo TX-NR609, HDR TV: Vizio M658-G1
L/R: Polk RT15i , C: Polk 245i , SL/SR: Polk Rt15i , SUB: Polk PSW-250
5js is offline  
Sponsored Links
Advertisement
 
post #32 of 41 Old 01-14-2020, 11:40 AM
AVS Forum Special Member
 
Augerhandle's Avatar
 
Join Date: Jan 2009
Location: About 25" away from my computer screen
Posts: 5,577
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 1392 Post(s)
Liked: 1350
Quote:
Originally Posted by 5js View Post
changing the subs polarity from 0 to 180 will invert the phase, correct? ...
Quote:
Originally Posted by desertdome View Post
That is not correct. Here is one fairly simple explanation: Polarity? Phase? What is the difference?...

From your link:

Quote:
polarity and phase are actually the same thing. Stay with me for the next few practical sections, and then I'll expand on the math.
Quote:
when we reverse the polarity of a complex waveform, the phase of every single frequency component is changed by 180°.

"The wise understand by themselves; fools follow the reports of others"-Tibetan Proverb
_____________________ http://www.scientificamerican.com/article/auger-handle/ ________________________
Augerhandle is offline  
post #33 of 41 Old 01-14-2020, 11:51 AM
AVS Forum Special Member
 
Augerhandle's Avatar
 
Join Date: Jan 2009
Location: About 25" away from my computer screen
Posts: 5,577
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 1392 Post(s)
Liked: 1350
Quote:
Originally Posted by 5js View Post
no. All speaker were physically connected to the AVR.
Okay, thanks for confirming.

"The wise understand by themselves; fools follow the reports of others"-Tibetan Proverb
_____________________ http://www.scientificamerican.com/article/auger-handle/ ________________________
Augerhandle is offline  
Sponsored Links
Advertisement
 
post #34 of 41 Old 01-14-2020, 11:53 AM - Thread Starter
5js
Member
 
5js's Avatar
 
Join Date: Mar 2012
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 10
Quote:
Originally Posted by Augerhandle View Post
Okay, thanks for confirming.
for my own education, how does this affect anything?

REC: Onkyo TX-NR609, HDR TV: Vizio M658-G1
L/R: Polk RT15i , C: Polk 245i , SL/SR: Polk Rt15i , SUB: Polk PSW-250
5js is offline  
post #35 of 41 Old 01-14-2020, 12:14 PM
AVS Forum Special Member
 
Augerhandle's Avatar
 
Join Date: Jan 2009
Location: About 25" away from my computer screen
Posts: 5,577
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 1392 Post(s)
Liked: 1350
Quote:
Originally Posted by 5js View Post
for my own education, how does this affect anything?
As I stated earlier, those sharp downward dips in the response look (to me) like destructive interference due to phase differences with your other speakers. If the phase differences are closer to 180° (say, 135°-225°) switching polarity should help. If the phase differences are closer to 0° (let's say, 315°-45°), switching polarity should make it worse. Either way, fine tuning the phase using delay might be necessary.

"The wise understand by themselves; fools follow the reports of others"-Tibetan Proverb
_____________________ http://www.scientificamerican.com/article/auger-handle/ ________________________
Augerhandle is offline  
post #36 of 41 Old 01-14-2020, 12:22 PM - Thread Starter
5js
Member
 
5js's Avatar
 
Join Date: Mar 2012
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 10
Quote:
Originally Posted by Augerhandle View Post
As I stated earlier, those sharp downward dips in the response look (to me) like destructive interference due to phase differences with your other speakers. If the phase differences are closer to 180° (say, 135°-225°) switching polarity should help. If the phase differences are closer to 0° (let's say, 315°-45°), switching polarity should make it worse. Either way, fine tuning the phase using delay might be necessary.
While the other speakers were "connected" each sweep was output individually to each speaker. I did a sweep with signal ONLY coming from the left speaker, then another sweep with signal ONLY coming from the right speaker, then a sweep with signal ONLY coming from the Sub.

Anyway - the sub sweeps were only done to help identify the preferred location for a new sub. I am not planning to tweaking the setup of this sub as I am looking for a sub that is more suitable for my setup as the current sub doesn't work well for the LFE in movies.

What I am looking for is a recommendation for a sub and currently looking at a couple of VBSS's, and IB install, or a sub based on the Ultimax 18 (sealed 4 cu ft box or a ported design like a mini or micro marty).

REC: Onkyo TX-NR609, HDR TV: Vizio M658-G1
L/R: Polk RT15i , C: Polk 245i , SL/SR: Polk Rt15i , SUB: Polk PSW-250
5js is offline  
post #37 of 41 Old 01-14-2020, 12:29 PM
AVS Forum Special Member
 
Augerhandle's Avatar
 
Join Date: Jan 2009
Location: About 25" away from my computer screen
Posts: 5,577
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 1392 Post(s)
Liked: 1350
Quote:
Originally Posted by 5js View Post
While the other speakers were "connected" each sweep was output individually to each speaker. I did a sweep with signal ONLY coming from the left speaker, then another sweep with signal ONLY coming from the right speaker, then a sweep with signal ONLY coming from the Sub...
Thanks for clearing that up. I must have missed the sweeps from the L and R speakers only. If that is the case, then the dips are definitely nulls from placement locations. Just choose the location with the best looking graph, and EQ from there.

"The wise understand by themselves; fools follow the reports of others"-Tibetan Proverb
_____________________ http://www.scientificamerican.com/article/auger-handle/ ________________________
Augerhandle is offline  
post #38 of 41 Old 01-14-2020, 01:12 PM
AVS Forum Special Member
 
desertdome's Avatar
 
Join Date: Aug 2004
Location: Omaha, NE
Posts: 3,796
Mentioned: 325 Post(s)
Tagged: 0 Thread(s)
Quoted: 1546 Post(s)
Liked: 1847
Quote:
. . .polarity and phase are actually the same thing. Stay with me for the next few practical sections, and then I'll expand on the math.
That is only true if you time shift the signal back to overlay over the original waveform - which defeats the concept of phase. The graphs in the article Phase or Polarity? illustrate the difference between polarity and phase.

Ponderosa Theater
High Impact AV
- ISF Level III Video Calibrator, THX-HAA HT3 Audio Designer/Calibrator
-StormAudio ISP 3D.32 Elite AVB; Cherry Megaschino amps; JTR Speakers Noesis 215RM's (5), S8's (10), & Captivator S2's (4); JTR NX7; Lumagen 4442; JRiver Media Center
desertdome is offline  
post #39 of 41 Old 01-14-2020, 04:30 PM
AVS Forum Special Member
 
Join Date: Jul 2014
Posts: 4,760
Mentioned: 480 Post(s)
Tagged: 0 Thread(s)
Quoted: 3072 Post(s)
Liked: 13086
Quote:
Originally Posted by Augerhandle View Post
Agreed, except I strongly suspect he is running the sweeps with all speakers connected.
Whether they are connected or not doesn't matter. It only matters if the sweeps were crossing from the sub to the mains. The sweeps he posted all appear to be sub only, so there is no crossover and no phase interaction.
Quote:
Originally Posted by Augerhandle View Post
Thanks for clearing that up. I must have missed the sweeps from the L and R speakers only. If that is the case, then the dips are definitely nulls from placement locations. Just choose the location with the best looking graph, and EQ from there.
I don't think he posted any of L and R. The only ones I see are sub only.

Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
aron7awol is offline  
post #40 of 41 Old 01-15-2020, 04:58 AM - Thread Starter
5js
Member
 
5js's Avatar
 
Join Date: Mar 2012
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 10
Quote:
Originally Posted by aron7awol View Post
Whether they are connected or not doesn't matter. It only matters if the sweeps were crossing from the sub to the mains. The sweeps he posted all appear to be sub only, so there is no crossover and no phase interaction.

I don't think he posted any of L and R. The only ones I see are sub only.
This shows the L, R, and Sub. All measurements taken individually - so no crossover or phase interaction

Attached Thumbnails
Click image for larger version

Name:	SPL LRSub.jpg
Views:	32
Size:	232.0 KB
ID:	2670228  

REC: Onkyo TX-NR609, HDR TV: Vizio M658-G1
L/R: Polk RT15i , C: Polk 245i , SL/SR: Polk Rt15i , SUB: Polk PSW-250
5js is offline  
post #41 of 41 Old 01-15-2020, 08:43 AM
AVS Forum Special Member
 
JohnDean's Avatar
 
Join Date: Jul 2012
Location: Franklin, TN
Posts: 1,449
Mentioned: 28 Post(s)
Tagged: 0 Thread(s)
Quoted: 566 Post(s)
Liked: 262
FWIW, the only reason I suggested the sealed Ultimax is because of size in your room. If you're ok having a minifridge somewhere in the room, then Full or Mini marty is going to outperform the sealed.

You could EQ the sealed sub and beat the performance you currently have by a mile, or build a ported design and beat it by 2 miles(At the cost of a larger cabinet.)
Heide264 likes this.
JohnDean is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off