Your Home Theater ULF Score - Page 155 - AVS Forum | Home Theater Discussions And Reviews
Baselworld is only a few weeks away. Getting the latest news is easy, Click Here for info on how to join the Watchuseek.com newsletter list. Follow our team for updates featuring event coverage, new product unveilings, watch industry news & more!



Forum Jump: 
 502Likes
Reply
 
Thread Tools
post #4621 of 4645 Old 08-21-2016, 10:57 AM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
Quote:
Originally Posted by dominguez1 View Post
Also, can you compare a horn vs ported at tune and see if PVL differs between the two?
I will run some more sims later but I did a quick one using submaximus v3 as an example. I applied voltage to produce 83dB at ~20Hz (which is about where its knee is) and then created a simple BR box for the infinity 1260w with a sensible port size (aka shouldn't be audible if you drove it to xmax). This shows that particle velocity at the horn mouth is way way lower than the BR box at 20Hz, as in 0.05m/s for the horn vs ~1m/s for the BR. If PV dominates for NF use then it's clear that BR is the way to go.

I suppose this is intuitively obvious when you think about it, the horn can produce ear shattering SPL so the velocity at the mouth has to be pretty low at low volumes otherwise it couldn't easily deliver that sort of SPL.

I guess that means the recipe is horns at the front + BR NF if PVL is what you want.
3ll3d00d is offline  
Sponsored Links
Advertisement
 
post #4622 of 4645 Old 08-21-2016, 12:04 PM
AVS Special Member
 
coolrda's Avatar
 
Join Date: Nov 2002
Location: Bakersfield, CA
Posts: 2,652
Mentioned: 100 Post(s)
Tagged: 0 Thread(s)
Quoted: 640 Post(s)
Liked: 491
Well done 3 and a good start. I wonder if this can be extended into the room, 3D model it, like a polar plot. Maybe something like this could be tried with REW/Omnimic by moving the mic back from the sub. You would have to overlay graphs but it would essentially give you multi array mics if this would work.
coolrda is offline  
post #4623 of 4645 Old 08-21-2016, 01:19 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 20,053
Mentioned: 320 Post(s)
Tagged: 1 Thread(s)
Quoted: 2137 Post(s)
Liked: 2359
interesting conversation. i don't really have anything to add at first pass, but will continue to ponder and follow...

Listen. It's All Good.
LTD02 is offline  
post #4624 of 4645 Old 08-21-2016, 02:11 PM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
This was quite tedious to calculate given the way hornresp works but I'm such a fun guy that I did it anyway

1st model is a UXL18 NF, no large coil adjustment made here because I don't think it is relevant to this particular point. A simple sealed 100L box with a v short horn segment (approx the CSA of the baffle) added to allow me to probe velocity at the mouth.

Click image for larger version

Name:	uxl18nf.png
Views:	10
Size:	42.0 KB
ID:	1615753

2nd model is a single infinity 1260w in a similar sized box but with a fairly large port added (so the total enclosure will be rather larger obviously) to allow a 14Hz tune. This is much lower than you'd probably ever tune this driver for HT use but we just want those particles moving so forget audibility

Click image for larger version

Name:	infinity_14.png
Views:	9
Size:	36.4 KB
ID:	1615761

I then manually scaled the voltage applied to achieve 95.4dB (no rhyme or reason to this value, just a big enough number to push the systems a bit) at each given frequency and read off the particle velocity and excursion. I did this separately for both the port outlet and direct radiator for the ported system so we could see how the relative output scales and where the port crosses, in PVL terms, to the driver.

SPL is in dB, velocity in m/s

Note the ported sub has N/A at 10Hz because the driver would have been destroyed if I made it produce 95.4dB at 10Hz , i.e. it needs a HPF. This would attentuate the output in the mid teens somewhat so the port velocities might be a touch higher than reality. I don't think I can combine hornresp's filter support with the particle velocity though so that would be quite onerous to work out. The port velocity is so much higher than the driver anyway that I don't think it really matters, the question (if the aim is a flattish TR) is likely to be how do you arrest output around tune as opposed to how do you maximise it.

Code:
		Driver			Port	
Sub	Hz	SPL	Velocity	Excursion	SPL	Velocity
UXL NF	10	95.4	0.5667	20		
UXL NF	12	95.4	0.4582	13.8859		
UXL NF	14	95.4	0.3921	10.1541		
UXL NF	16	95.4	0.345	7.8539		
UXL NF	18	95.4	0.3086	6.2653		
UXL NF	20	95.4	0.2785	5.1158		
UXL NF	22	95.4	0.2509	4.1686		
UXL NF	24	95.4	0.2313	3.5279		
UXL NF	26	95.4	0.2117	2.9585		
UXL NF	28	95.4	0.1987	2.5889		
UXL NF	30	95.4	0.1849	2.242		
Infinity 14	10	N/A				
Infinity 14	12	82.8808	0.5119	6.7651	97.24	9.8508
Infinity 14	14	72.98	0.1399	1.5798	93.6	5.5371
Infinity 14	16	83.4765	0.4119	4.0891	91.5701	3.9905
Infinity 14	18	86.8441	0.5414	4.7934	89.652	2.7552
Infinity 14	20	89.8845	0.6852	5.4113	88.8804	2.2485
Infinity 14	22	90.7917	0.6981	5.0599	87.4322	1.7467
Infinity 14	24	91.9187	0.7101	4.7231	86.253	1.3996
Infinity 14	26	92.2688	0.6971	4.2557	84.9831	1.1098
Infinity 14	28	92.669	0.6796	3.8627	83.9743	0.9199
Infinity 14	30	92.7555	0.6483	3.4797	83.0136	0.7778
coolrda and dominguez1 like this.

Last edited by 3ll3d00d; 08-21-2016 at 02:16 PM.
3ll3d00d is offline  
post #4625 of 4645 Old 08-21-2016, 02:23 PM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
my conclusions....

a low tune port has vastly much more PVL than a sealed sub for an octave or so above tune
an aggressively LT'ed sealed sub can't compete with a simple port in PVL terms
a ported sub has the driver PVL added to it as the port falls away so placing the port near the driver is probably a good idea (if you want to concentrate firepower into a particular seat)
a port can be split n ways so you could build one sub and aim multiple ports at different seats (off the shelf design need not apply, I imagine this would require a custom design/fold per seating area)

I'm thinking that the ideal "sub as TR delivery mechanism" might be a big ported box with multiple ducts fanning out with each one aiming at a single seat (& then a few horns at the front to sandblast your face!)
dominguez1 likes this.
3ll3d00d is offline  
post #4626 of 4645 Old 08-21-2016, 07:12 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
Quote:
Originally Posted by 3ll3d00d View Post
This was quite tedious to calculate given the way hornresp works but I'm such a fun guy that I did it anyway

1st model is a UXL18 NF, no large coil adjustment made here because I don't think it is relevant to this particular point. A simple sealed 100L box with a v short horn segment (approx the CSA of the baffle) added to allow me to probe velocity at the mouth.

Attachment 1615753

2nd model is a single infinity 1260w in a similar sized box but with a fairly large port added (so the total enclosure will be rather larger obviously) to allow a 14Hz tune. This is much lower than you'd probably ever tune this driver for HT use but we just want those particles moving so forget audibility

Attachment 1615761

I then manually scaled the voltage applied to achieve 95.4dB (no rhyme or reason to this value, just a big enough number to push the systems a bit) at each given frequency and read off the particle velocity and excursion. I did this separately for both the port outlet and direct radiator for the ported system so we could see how the relative output scales and where the port crosses, in PVL terms, to the driver.

SPL is in dB, velocity in m/s

Note the ported sub has N/A at 10Hz because the driver would have been destroyed if I made it produce 95.4dB at 10Hz , i.e. it needs a HPF. This would attentuate the output in the mid teens somewhat so the port velocities might be a touch higher than reality. I don't think I can combine hornresp's filter support with the particle velocity though so that would be quite onerous to work out. The port velocity is so much higher than the driver anyway that I don't think it really matters, the question (if the aim is a flattish TR) is likely to be how do you arrest output around tune as opposed to how do you maximise it.

Code:
		Driver			Port	
Sub	Hz	SPL	Velocity	Excursion	SPL	Velocity
UXL NF	10	95.4	0.5667	20		
UXL NF	12	95.4	0.4582	13.8859		
UXL NF	14	95.4	0.3921	10.1541		
UXL NF	16	95.4	0.345	7.8539		
UXL NF	18	95.4	0.3086	6.2653		
UXL NF	20	95.4	0.2785	5.1158		
UXL NF	22	95.4	0.2509	4.1686		
UXL NF	24	95.4	0.2313	3.5279		
UXL NF	26	95.4	0.2117	2.9585		
UXL NF	28	95.4	0.1987	2.5889		
UXL NF	30	95.4	0.1849	2.242		
Infinity 14	10	N/A				
Infinity 14	12	82.8808	0.5119	6.7651	97.24	9.8508
Infinity 14	14	72.98	0.1399	1.5798	93.6	5.5371
Infinity 14	16	83.4765	0.4119	4.0891	91.5701	3.9905
Infinity 14	18	86.8441	0.5414	4.7934	89.652	2.7552
Infinity 14	20	89.8845	0.6852	5.4113	88.8804	2.2485
Infinity 14	22	90.7917	0.6981	5.0599	87.4322	1.7467
Infinity 14	24	91.9187	0.7101	4.7231	86.253	1.3996
Infinity 14	26	92.2688	0.6971	4.2557	84.9831	1.1098
Infinity 14	28	92.669	0.6796	3.8627	83.9743	0.9199
Infinity 14	30	92.7555	0.6483	3.4797	83.0136	0.7778
@3ll3d00d

This is the biggest discovery we've had about the physics behind PVL and subs!

This was the hypothesis we had back 3 years ago here where we said that around tune, ported produced more PVL than sealed, thereby increasing Sound Intensity and being detected via increased vibrations in the HT seating. Little did we know hornresp had already included this as part of the sim! Wow...huge, just huge.

Now, before I go "all in" with hornresp, I've got some more questions...

In your table above the columns are off, so they are difficult to match up. But it looks to me that the ported sub (infinity) has greater PV at all frequencies? Look at 30hz, velocity of the driver is .6843 compared to the sealed at .1849. Additionally, the port's PV is .7778. Should those be added to get total PV? Both of those velocities coming from the infinity are multiples above the sealed...how did you determine that the increased PV is only one octave above or so?

Is it possible for you to graph this data so it's easier to view? I would, except I'm not sure I'm reading the data correctly.
dominguez1 is online now  
post #4627 of 4645 Old 08-21-2016, 07:17 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
Quote:
Originally Posted by 3ll3d00d View Post
my conclusions....

a low tune port has vastly much more PVL than a sealed sub for an octave or so above tune
an aggressively LT'ed sealed sub can't compete with a simple port in PVL terms
Ahhh...me likey.

Quote:
a ported sub has the driver PVL added to it as the port falls away so placing the port near the driver is probably a good idea (if you want to concentrate firepower into a particular seat)
a port can be split n ways so you could build one sub and aim multiple ports at different seats (off the shelf design need not apply, I imagine this would require a custom design/fold per seating area)

I'm thinking that the ideal "sub as TR delivery mechanism" might be a big ported box with multiple ducts fanning out with each one aiming at a single seat (& then a few horns at the front to sandblast your face!)
I love this....designing subs to optimize PVL and 'aiming' the PVL at seats...
dominguez1 is online now  
post #4628 of 4645 Old 08-21-2016, 07:20 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
@3ll3d00d

While you're feeling curious...

Do larger drivers produce more PVL than smaller ones?

Does larger xmax drivers produce more PVL than smaller xmax drivers that have the same diameter?
dominguez1 is online now  
post #4629 of 4645 Old 08-21-2016, 07:40 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
@SBuger

Great reviews of your experience with TTs and NF! That was very helpful to our discussion!

@derrickdj1

Also, great feedback. Similar to sbuger's response

@coolrda

Argghh..."Resistance is Futile"....this is the message I keep getting from you about Crowsons...feelin' weak, damn you!

So, here's where I've landed on the scorecard:

I'm hearing you guys about the TTs...they ADD to the overall experience if done right. It's different that what the NFs provide, and provides a different type of TR that NF subs probably can't create.

I'm also hearing that NFs do provide something that TTs do not. But, coolrda believes in his room, he has a better experience without NFs, but further away with the crowsons implemented.

Based on the above, and since we have no reference for PR (as it may differ by room), I won't be including the score in the TOTAL or Performance Level row. The calculation for Total Performance will be solely based on things we can measure (FR, SPL, TR).

HOWEVER...I still we be including it as a line in the spreadsheet for additional context. Clearly, PR plays a significant role in what we experience (as I, sbuger, derrickdj1, mk, and many others have witnessed). And although we can't measure it, it doesn't mean we shouldn't acknowledge it. I will still used my 'imperfect' calculation to estimate PR...and by me showing this data with different setups, it will give us more info to refine the calculation over time.

So, if two people have the same performance levels, and we visit each one and find they are different, PR might be one of the differentiating factors (e.g. HT with no NF subs, but perfect TR with TTs vs an HT with NF subs and TTs) and we could check the PR estimate to help explain.

Sound good?
SBuger likes this.
dominguez1 is online now  
post #4630 of 4645 Old 08-21-2016, 08:03 PM
AVS Special Member
 
coolrda's Avatar
 
Join Date: Nov 2002
Location: Bakersfield, CA
Posts: 2,652
Mentioned: 100 Post(s)
Tagged: 0 Thread(s)
Quoted: 640 Post(s)
Liked: 491
Ha! Bringing the Borg into this discussion are we. Actually it's a clean sweep as I still have the NF sub. Originally had the 4x then went to the 8x and now back to the 4x. So I need to clarify that important point. If it wasn't for the Fatboy sub with its slot loading I'm sure I would have preferred the 4x directly behind the seat.
coolrda is offline  
post #4631 of 4645 Old 08-21-2016, 08:32 PM
AVS Special Member
 
derrickdj1's Avatar
 
Join Date: Sep 2011
Posts: 3,148
Mentioned: 65 Post(s)
Tagged: 0 Thread(s)
Quoted: 718 Post(s)
Liked: 513
Quote:
Originally Posted by dominguez1 View Post
@SBuger

Great reviews of your experience with TTs and NF! That was very helpful to our discussion!

@derrickdj1

Also, great feedback. Similar to sbuger's response

@coolrda

Argghh..."Resistance is Futile"....this is the message I keep getting from you about Crowsons...feelin' weak, damn you!

So, here's where I've landed on the scorecard:

I'm hearing you guys about the TTs...they ADD to the overall experience if done right. It's different that what the NFs provide, and provides a different type of TR that NF subs probably can't create.

I'm also hearing that NFs do provide something that TTs do not. But, coolrda believes in his room, he has a better experience without NFs, but further away with the crowsons implemented.

Based on the above, and since we have no reference for PR (as it may differ by room), I won't be including the score in the TOTAL or Performance Level row. The calculation for Total Performance will be solely based on things we can measure (FR, SPL, TR).

HOWEVER...I still we be including it as a line in the spreadsheet for additional context. Clearly, PR plays a significant role in what we experience (as I, sbuger, derrickdj1, mk, and many others have witnessed). And although we can't measure it, it doesn't mean we shouldn't acknowledge it. I will still used my 'imperfect' calculation to estimate PR...and by me showing this data with different setups, it will give us more info to refine the calculation over time.

So, if two people have the same performance levels, and we visit each one and find they are different, PR might be one of the differentiating factors (e.g. HT with no NF subs, but perfect TR with TTs vs an HT with NF subs and TTs) and we could check the PR estimate to help explain.

Sound good?
This sounds like a excellent way to proceed. An a reference to the PR will certainly work as described!!!
derrickdj1 is online now  
post #4632 of 4645 Old 08-21-2016, 09:02 PM
AVS Special Member
 
coolrda's Avatar
 
Join Date: Nov 2002
Location: Bakersfield, CA
Posts: 2,652
Mentioned: 100 Post(s)
Tagged: 0 Thread(s)
Quoted: 640 Post(s)
Liked: 491
Quote:
Originally Posted by dominguez1 View Post
Based on the above, and since we have no reference for PR (as it may differ by room)

HOWEVER...I still we be including it as a line in the spreadsheet for additional context. Clearly, PR plays a significant role in what we experience (as I, sbuger, derrickdj1, mk, and many others have witnessed). And although we can't measure it, it doesn't mean we shouldn't acknowledge it. I will still used my 'imperfect' calculation to estimate PR...and by me showing this data with different setups, it will give us more info to refine the calculation over time.
Here's my subs speaking in Dom's behalf.

SBuger and dominguez1 like this.
coolrda is offline  
post #4633 of 4645 Old 08-22-2016, 04:40 AM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
@dominguez1 it is tab delimited, you can import it into excel or libre office or similar. I will add graphs later though I don't know how pvl might sum, not sure if it is a vector and/or has phase.
3ll3d00d is offline  
post #4634 of 4645 Old 08-22-2016, 09:03 AM
Senior Member
 
SBuger's Avatar
 
Join Date: Sep 2005
Location: Albuquerque, NM
Posts: 227
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked: 128
Quote:
Originally Posted by derrickdj1 View Post
In my room I'm good down to around 12-13 Hz. Nearfield sub without the transducer is different than using less spl and with the TT's and nearfield subs. Is one better, I can't say that. I watch some movies +/- transducers and find it equally enjoyable.

Now, running things hot means more spl and pressure. I don't find this more enjoyable. I thinks there is a point that enough of each component leads to a balance and enjoyable experience. To much of any one can ruin the expeience. Now, what all of us like will vary from pereson to person and room to room.

I have a large room but, I routinely watch movies with some doors open to keep down the weighted feeling. Even to much bopping on the back and seat bottom can become a distraction. This point with PR and TR is subjective because what one person considers enough may be to much or not enough for another person.

I will say that I'm in a very comfortable place because I can easily tailor the TR/PR/ and spl max quickly. The TT's are nice to have because you can so quickly and easily adjust the TR. Most of us have enough spl and are looking for the TR +/- the PR.
I concur that to much bopping on the back of the seat (and even the seat bottom) can become a distraction and there needs to be balance for the most enjoyable experience. I've found that I can minimize this effect on the back of the seat from the NF's by EQ'ing that 30-50ish hz area down a little (about 3-5db) compared to the frequencies above and below that. Then let the farfield subs fill in that dip. That frequency range seems to create the most bop on the back feeling for me. Another thing that has helped me with that feeling of too much direct bopping on the back (which can be a problem with drivers only a couple inches way from back of your seat) is to have more than one NF only directly behind me. Having two more (one on each side of the main driver right behind MLP helps distribute the direct hit in the back feeling a little bit better). The same thing can be accomplished by moving the sub a little further away from the couch or lowering the gain on the sub or subs. But I find the closer the better for the most intense ULF wobble sensations, which never seems back bopping to me.

I hear you on being able to tailor the TR/PR and SPL quickly. I do the same thing (sometimes because of mood or particular movie). Its a wonderful thing to be able to do IMO. I know most like to set and forget everything, but I love having the ability to make small adjustments to subs and or TT's very quickly and easily on the fly. My TT's are easy to do this with because I have them tied into my Oppo and just use the Volume control for there intensity. Then I can get to my sub trims quickly and easy. Two trims if I have the subs on two subs outs (NF's on one and FF on another) or just one trim if I have them both on just one sub out. Most of the time I pretty much leave everything where it is, but do change it sometimes. It's nice though that when I turn my AVR off, subs trims return back to the default setting where I set them (usually about 4-5 db hot).

My SI DS4-18 (x4) Sub Build
AVR/Player: Onkyo TX-NR5010, Oppo BDP-103
Video: Samsung PN64F8500 Plasma, Epson 5030UB Projector, Darbee, SeymourAV 120" Retractable AT Screen
Speakers: KEF Q Series (Fronts: Q900's, Center: Q600C, Surrounds & Heights: KEF In-Walls)
Subs/TT's: SI DS4-18(x4), Inuke6000DSP(x2), BK LFE(x2), Crowson Shadow-8 MA(x2), BK Amp(x2), MiniDSP 2x4
SBuger is online now  
post #4635 of 4645 Old 08-22-2016, 01:01 PM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
@dominguez1 here's a chart comparing velocity of the 3 sources of PVL (UXL18 sealed in grey vs the infinity driver/port)

Attached Thumbnails
Click image for larger version

Name:	v_comp.png
Views:	61
Size:	33.5 KB
ID:	1617049  
dominguez1 likes this.
3ll3d00d is offline  
post #4636 of 4645 Old 08-22-2016, 01:57 PM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
Quote:
Originally Posted by dominguez1 View Post
@3ll3d00d

While you're feeling curious...

Do larger drivers produce more PVL than smaller ones?

Does larger xmax drivers produce more PVL than smaller xmax drivers that have the same diameter?
PVL of a sealed sub, according to hornresp, scales linearly with volume displaced

50L 1260w vs 100L UXL-18, voltages scaled to produce 86.4dB at each frequency. PVL from each one is basically identical and I suspect it would be identical if I could access the underlying equations directly. If you multiply Sd by excursion then you'll find the volume displaced is also identical hence PVL, in this model, is simply volume displaced expressed in a different unit.



This is interesting because it means the only reason to use a bigger NF sub for PVL is to be able to drive it harder lower down.

I'm not sure how to compare this to the measurement of particle velocity coming off the driver in a ported sub though as the previous example had more PVL from the ported driver vs the sealed. Arguably it doesn't really matter as the port has so much more it will really drown out the driver.

It also means something like an SI HST11 or 12 would be a great, if rather expensive, choice for a compact TR delivery mechanism. You could run them dual opposed between 2 rows of seats with one end giving some trouser flapping action and/or a foot rest and the other end giving the back massage
Attached Thumbnails
Click image for larger version

Name:	v_comp.png
Views:	63
Size:	25.4 KB
ID:	1617193  
dominguez1 likes this.

Last edited by 3ll3d00d; 08-22-2016 at 02:03 PM.
3ll3d00d is offline  
post #4637 of 4645 Old 08-22-2016, 06:14 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
Quote:
Originally Posted by 3ll3d00d View Post
@dominguez1 here's a chart comparing velocity of the 3 sources of PVL (UXL18 sealed in grey vs the infinity driver/port)

This is fantastic. It's very clear that ported subs around tune produce more PVL. This was just a hypothesis until your findings. Now it is clear as day!

This is HUGE my friends!

Since we turned to the last page for answers....

What happens to PV below tune? Is it a significant drop off (it doesn't appear to be).

Do additional ports increase or decrease PV?

Is it easy for you to model other designs so that we have one chart? I will certainly use this in my first few posts somewhere!

Can you model a passive radiator? How about a bandpass design? Others?

EDIT: Can you also throw in a horn to complete the graph?

Sorry, I'm like a kid in a candy store...

Last edited by dominguez1; 08-22-2016 at 06:26 PM.
dominguez1 is online now  
post #4638 of 4645 Old 08-22-2016, 06:23 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
Quote:
Originally Posted by 3ll3d00d View Post
PVL of a sealed sub, according to hornresp, scales linearly with volume displaced

50L 1260w vs 100L UXL-18, voltages scaled to produce 86.4dB at each frequency. PVL from each one is basically identical and I suspect it would be identical if I could access the underlying equations directly. If you multiply Sd by excursion then you'll find the volume displaced is also identical hence PVL, in this model, is simply volume displaced expressed in a different unit.



This is interesting because it means the only reason to use a bigger NF sub for PVL is to be able to drive it harder lower down.

I'm not sure how to compare this to the measurement of particle velocity coming off the driver in a ported sub though as the previous example had more PVL from the ported driver vs the sealed. Arguably it doesn't really matter as the port has so much more it will really drown out the driver.

It also means something like an SI HST11 or 12 would be a great, if rather expensive, choice for a compact TR delivery mechanism. You could run them dual opposed between 2 rows of seats with one end giving some trouser flapping action and/or a foot rest and the other end giving the back massage
We are really unraveling a mystery here...another great data point!

So, based on this, can we conclude that a sealed design producing a clean 'x' db output will produce the same PVL for that output regardless of the size or xmax of the driver?
dominguez1 is online now  
post #4639 of 4645 Old Yesterday, 03:06 AM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
Quote:
Originally Posted by dominguez1 View Post
What happens to PV below tune? Is it a significant drop off (it doesn't appear to be).
PVL shape tracks the shape of the port output (as you might expect) though the peak appears to occur a bit below tuning, here's a random port which has peak output at 16Hz but the peak PVL is at ~13.5Hz. This suggests tuning a bit higher than the target for peak PVL is a good idea.

Click image for larger version

Name:	random_port.png
Views:	4
Size:	24.9 KB
ID:	1618025

Quote:
Originally Posted by dominguez1 View Post
Do additional ports increase or decrease PV?
particle velocity appears to be closely related to air speed in the port though not exactly the same thing, I don't know how they differ. However making the port smaller will increase air speed so it will increase PVL, this will ultimately lead to audible distress and compression though so you can't really push that aspect. I don't know how a sub responds if you add different sized ports, I think only akabak can model this. Intuitively it seems like it might destabilise the system though I can also see how you might be able to leverage this to optimise PVL delivery out of different ports. I think this would be particularly useful if you were adding a series of subs behind a row of seats and hence used some asymmetry in the ports to attempt to equalise PVL across a space. I might try to do this for my setup, at least attempt to model it anyway.

Quote:
Originally Posted by dominguez1 View Post
[Is it easy for you to model other designs so that we have one chart? I will certainly use this in my first few posts somewhere!
it's possible, a whole load of work though as it's an entirely manual process fiddling hornresp params to produce a given output. I'm not sure how useful it is either when there appear to be some simple rules to apply.

Quote:
Originally Posted by dominguez1 View Post
Can you model a passive radiator?
I'm not sure how to model a PR in hornresp but I would expect it to behave like a sealed sub anyway as a PR is just a cone moving in and out.

Quote:
Originally Posted by dominguez1 View Post
How about a bandpass design? Others?
I posted a while ago that I thought a 6th order BP would be perfect for TR in its bandwidth. This is pretty impractical (*waits for someone to build it*) but here's a BP6 using a UXL18 that operates in the ~12-60Hz range. Having said that it's smaller than a submaximus, shifts the useable bandwidth a bit lower down, has a reasonable amount less output (so you'd probably need 2 to compete in SPL terms) produces a lot more PVL so if PVL is your goal then perhaps it isn't so impractical after all. On the plus side, submaximus has been built and works whereas this is something I just banged together in hornresp in 10minutes

schematic
Click image for larger version

Name:	bp6_uxl.png
Views:	5
Size:	8.3 KB
ID:	1617929

output (front, rear, combined)
Click image for larger version

Name:	bp6_uxl_front_output.png
Views:	5
Size:	30.2 KB
ID:	1617945
Click image for larger version

Name:	bp6_uxl_rear_output.png
Views:	5
Size:	30.3 KB
ID:	1617953
Click image for larger version

Name:	bp6_uxl_combined_output.png
Views:	5
Size:	30.4 KB
ID:	1617937

velocity (I had to do some image hacking to overlay the rear and front port velocities)

Click image for larger version

Name:	bp6_uxl_velocity.png
Views:	7
Size:	24.4 KB
ID:	1617961

I would not be surprised if you had to limit power into this to prevent compression in the ports. I'm not sure whether any model can tell you this or you just have to rely on rules of thumb.

Quote:
Originally Posted by dominguez1 View Post
EDIT: Can you also throw in a horn to complete the graph?
submaximus v3 at something close to peak output (120dB at 19Hz)

Click image for larger version

Name:	submaximusv3_output.png
Views:	3
Size:	32.1 KB
ID:	1617969
Click image for larger version

Name:	submaximusv3_velocity.png
Views:	4
Size:	35.6 KB
ID:	1617977

Quote:
Originally Posted by dominguez1 View Post
So, based on this, can we conclude that a sealed design producing a clean 'x' db output will produce the same PVL for that output regardless of the size or xmax of the driver?
yes that's what this says
dominguez1 likes this.

Last edited by 3ll3d00d; Yesterday at 03:11 AM.
3ll3d00d is offline  
post #4640 of 4645 Old Yesterday, 06:42 AM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
a slightly more feasible BP6 design using an infinity 1260w and aiming for ~16Hz to ~65Hz and which fits into 190L in total (4ft3 for the rear, 1.5ft3 for the front, the rest for the ports)

Click image for larger version

Name:	inf_bp.png
Views:	15
Size:	22.7 KB
ID:	1618153

Click image for larger version

Name:	inf_bp_output.png
Views:	9
Size:	27.7 KB
ID:	1618161

a word of caution on these results is that adding a large flare to the end to attempt to simulate the existence of a "slot" of air reduces the particle velocity from a peak of 17m/s to 0.7m/s, i.e. making it look like this

Click image for larger version

Name:	slot.png
Views:	9
Size:	5.1 KB
ID:	1618177

i.e. the particle velocity dissipates as it transitions into a larger space

Last edited by 3ll3d00d; Yesterday at 06:48 AM.
3ll3d00d is offline  
post #4641 of 4645 Old Yesterday, 04:49 PM
AVS Special Member
 
derrickdj1's Avatar
 
Join Date: Sep 2011
Posts: 3,148
Mentioned: 65 Post(s)
Tagged: 0 Thread(s)
Quoted: 718 Post(s)
Liked: 513
Quote:
Originally Posted by 3ll3d00d View Post
a slightly more feasible BP6 design using an infinity 1260w and aiming for ~16Hz to ~65Hz and which fits into 190L in total (4ft3 for the rear, 1.5ft3 for the front, the rest for the ports)

Attachment 1618153

Attachment 1618161

a word of caution on these results is that adding a large flare to the end to attempt to simulate the existence of a "slot" of air reduces the particle velocity from a peak of 17m/s to 0.7m/s, i.e. making it look like this

Attachment 1618177

i.e. the particle velocity dissipates as it transitions into a larger space
So what have you decided to build? Are you still going to use the ULX drivers?
derrickdj1 is online now  
post #4642 of 4645 Old Today, 03:32 PM
AVS Special Member
 
3ll3d00d's Avatar
 
Join Date: Sep 2007
Location: London, UK
Posts: 2,316
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1278 Post(s)
Liked: 437
Quote:
Originally Posted by derrickdj1 View Post
So what have you decided to build? Are you still going to use the ULX drivers?
I replied over here

dominguez1 likes this.
3ll3d00d is offline  
post #4643 of 4645 Old Today, 07:00 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
Quote:
Originally Posted by 3ll3d00d View Post
I'm not sure how to model a PR in hornresp but I would expect it to behave like a sealed sub anyway as a PR is just a cone moving in and out.
Yup, good point. I originally thought since a Passive Radiator's FR is shaped like a ported sub and has a 'tune', that perhaps it might generate more PVL around tune. But your discovery would imply that PV would stay similar, as it is a driver.
dominguez1 is online now  
post #4644 of 4645 Old Today, 07:03 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
Quote:
Originally Posted by 3ll3d00d View Post
a slightly more feasible BP6 design using an infinity 1260w and aiming for ~16Hz to ~65Hz and which fits into 190L in total (4ft3 for the rear, 1.5ft3 for the front, the rest for the ports)

Attachment 1618153

Attachment 1618161

a word of caution on these results is that adding a large flare to the end to attempt to simulate the existence of a "slot" of air reduces the particle velocity from a peak of 17m/s to 0.7m/s, i.e. making it look like this

Attachment 1618177

i.e. the particle velocity dissipates as it transitions into a larger space


^^^That is some massive PVL. At what db is this? In comparison, how does a ported PV look like at the same output?
dominguez1 is online now  
post #4645 of 4645 Old Today, 07:09 PM - Thread Starter
AVS Special Member
 
dominguez1's Avatar
 
Join Date: Dec 2008
Posts: 2,723
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked: 449
Quote:
Originally Posted by 3ll3d00d View Post
I replied over here

Ummmm...this is going to be awesome.

Will discuss in your build thread...

Spoiler!
dominguez1 is online now  
Sponsored Links
Advertisement
 
Reply Subwoofers, Bass, and Transducers

Tags
ae ib15 subwoofer , Bic Pl 200 Acoustech Platinum Series Subwoofer , Bowers Wilkins Asw 610 , Danley Sound Labs Dts 10 , Elemental Designs A7s 450 , Epik Empire , Fv15hp Subwoofer , Hsu Vtf 15h Subwoofer , Klipsch Sw 311 , Seaton Sound Submersive H P , Svs Pb12 Nsd Black Vinyl 12 Inch Powered Subwoofer , Svs Sb13 Ultra Piano Gloss 13 Inch 1000 Watt Powered Subwoofer , Velodyne Eq Max 15 15 Subwoofer



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