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post #1 of 15 Old 01-11-2019, 07:24 PM - Thread Starter
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Angry Problem - Upgraded SVS PC2000 to PC4000... and lost performance?

I am just confused. Per the REW graphs below, my PC-2000 seemed to run as good or better than I can initially run PC-4000. My ears agree.

I'm attaching the REW graphs of:
Green - PC-2000 @ SW Gain = 55%, Aud DyEQ=on, Aud SW Boost = ?
Blue - PC-2000 @ SW Gain = 75%, Aud DyEQ=on, Aud SW Boost = ?
Red - PC-4000 @ SW Gain = -7db [-60 to -0 range], Aud DyEQ = on, Aud SW Boost = off
The PC-2000 is equal or better.

Details:

I did a SVS 45-day return on my PC-2000 and also received a PC-4000 on the same day. I installed the 4000 in same exact spot, and I ran Audessey calibration (PC-4000 in Extended Mode (1 port closed)). I ran a demo movie clip and subjectively thought its performance was similar - equal or less - to the PC-2000. I then ran a REW measurement on the PC-4000 and found was nearly identical to the PC-2000. Is there a hypothetical where that should be the case?

Settings -
PC-2000: Subwoofer gain at 50%; run Audessey; it puts SW1 trim at -4db; I then turn SW1 gain to 55% on the knob. I generally kept Aud SW Boost = On, but the adjustment = 0 db unless on a few occasions i increased it to +5 db for movies/demos.
PC-4000: Using SVS App, put Subwoofer gain at -10 db per SVS instructions (there is no physical knob; the app has a scale of -60 db to -0 db). Isn't -10 db almost maxed out? I wonder to myself; I select Port Mode = Extended Mode, and I plug 1 port. I run Audessey; during calibration Audessey makes me adjust SW gain to -17 db to get its measurement close to 75 db; after calibration it puts SW1 trim at -5 db. I then adjust PC4000 gain via app to -7 db because general advice here is to turn up physical gain after Audessey, and I want more "oomph".

REW data PC2000 vs PC4000
I am new to REW, just got the UMIK this week.
The other day I ran REW on the PC-2000. AVR MV = -20db, Aud Dynamic EQ = On. The only variable is I did not note if Aud SW Boost = on/off/+whatever db (?)
The PC-4000 today, AVR MV = -20 db, gain at -7 db, with Aud SW Trim = -5db, Aud DyEQ = On and Aud SW Boost = Off is the most REW will allow. If I try to increase SW gain, or turn on Aud SW Boost, I get a REW error saying it detected clipping and/or it ran out of headroom (a red 0db or -3 db message).
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post #2 of 15 Old 01-11-2019, 08:19 PM
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Well the 4000 has a slightly larger driver and a more powerful amp, but the subs measure more or less the same FR-wise and your graphs reflect that. What that means is that they will sound the same at any given volume level when running within their limits; what you'll get with the 4000 is more headroom, I'd guess 4-5 DB across the board.


If the 2000 was producing more output at a given receiver volume level, then that has to do with setup- you mentioned a gain adjustment after audyssey with one and a channel level adjustment with the other - those adjustments were probably not identical. To gauge how much of an improvement the 4000 is you would want to see how loud each can go in your room before running out of steam, so to speak.


Edit - I just noticed you also plugged a port on the 4000 which would limit output to an extent also.
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post #3 of 15 Old 01-12-2019, 07:16 AM
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Quote:
Originally Posted by RobZL1 View Post
I am just confused. Per the REW graphs below, my PC-2000 seemed to run as good or better than I can initially run PC-4000. My ears agree.

I'm attaching the REW graphs of:
Green - PC-2000 @ SW Gain = 55%, Aud DyEQ=on, Aud SW Boost = ?
Blue - PC-2000 @ SW Gain = 75%, Aud DyEQ=on, Aud SW Boost = ?
Red - PC-4000 @ SW Gain = -7db [-60 to -0 range], Aud DyEQ = on, Aud SW Boost = off
The PC-2000 is equal or better.

Details:

I did a SVS 45-day return on my PC-2000 and also received a PC-4000 on the same day. I installed the 4000 in same exact spot, and I ran Audessey calibration (PC-4000 in Extended Mode (1 port closed)). I ran a demo movie clip and subjectively thought its performance was similar - equal or less - to the PC-2000. I then ran a REW measurement on the PC-4000 and found was nearly identical to the PC-2000. Is there a hypothetical where that should be the case?

Settings -
PC-2000: Subwoofer gain at 50%; run Audessey; it puts SW1 trim at -4db; I then turn SW1 gain to 55% on the knob. I generally kept Aud SW Boost = On, but the adjustment = 0 db unless on a few occasions i increased it to +5 db for movies/demos.
PC-4000: Using SVS App, put Subwoofer gain at -10 db per SVS instructions (there is no physical knob; the app has a scale of -60 db to -0 db). Isn't -10 db almost maxed out? I wonder to myself; I select Port Mode = Extended Mode, and I plug 1 port. I run Audessey; during calibration Audessey makes me adjust SW gain to -17 db to get its measurement close to 75 db; after calibration it puts SW1 trim at -5 db. I then adjust PC4000 gain via app to -7 db because general advice here is to turn up physical gain after Audessey, and I want more "oomph".

REW data PC2000 vs PC4000
I am new to REW, just got the UMIK this week.
The other day I ran REW on the PC-2000. AVR MV = -20db, Aud Dynamic EQ = On. The only variable is I did not note if Aud SW Boost = on/off/+whatever db (?)
The PC-4000 today, AVR MV = -20 db, gain at -7 db, with Aud SW Trim = -5db, Aud DyEQ = On and Aud SW Boost = Off is the most REW will allow. If I try to increase SW gain, or turn on Aud SW Boost, I get a REW error saying it detected clipping and/or it ran out of headroom (a red 0db or -3 db message).
Hi Rob,

Let's start over a little bit. You are new to REW and Denon has got some wonky settings. First, it is important to make sure that your subwoofer is in a good location in the room. Doing a sub crawl, while measuring the results, is a helpful way to go about that. Don't worry right now about whether the PC4000 is in exactly the same spot as the PC2000 was in. Just make sure that the location for the PC4000 is where it sounds and/or measures the strongest.

Then, for whatever spot you pick, including the current one, do a new Audyssey calibration. But, let's do it a little differently this time. Try to get a trim level of about -11, but not -12. That means that you will probably need to be closer to the gain setting you originally started with. Ignore Audyssey telling you to reduce your SPL to 75db. It's okay to be higher than that in order to get a strongly negative trim level. On your Denon, you should be able to tell Audyssey to calculate after three mic positions. That will let you see what your trim level is before doing the full 8-point calibration. (All of this is covered in Section II-C of the Guide, linked below.)

Once you have finished calibrating, you can turn your AVR trim up to about -5 or -6 with the test tone adjustment. Don't use the Denon feature called "Subwoofer Level Adjust". That actually resets your trim level to 0.0, and any trim you add puts you in positive numbers. That can result in clipping at any significant master volume. You can also turn-up the volume from the sub gain itself. Go as high as you like with that. If you want to be at -5 on the PC4000's digital reading, that is okay.

Now, listen to a movie with good low-bass content, and measure the results if you like. There won't be a lot of difference between the PC2000 and the PC4000 (in Extended one-port mode) above about 60Hz. So, for mid-bass they should sound pretty similar. The PC4000 in 16Hz mode, though, will have more SPL below that 60Hz frequency than the PC2000. There is a pretty good difference (~7db) at 50Hz and at 40Hz. Then, the difference levels-out more as you approach the port tune of the PC2000, and the difference is only about 3db or so. But, the difference is back up to almost 6db at 20Hz, and below 20Hz is where the real difference lies. With the right movie content, the PC4000 will produce much more <25Hz SPL and TR. And, it will keep producing SPL below 20Hz, long after the PC2000 has run completely out of gas. But, the content has to be there. Otherwise, you will just hear a little more bass weight.

Here are measurements for the two subwoofers from different testing sources. You want to compare the 2m measurements for the PC2000 to the Audioholics measurements for the PC4000. You should beat those numbers in your room, since you will get some room gain. But, you will also get some room modes at random frequencies, which is why it is helpful to use REW to pick your best subwoofer location.

http://www.lifewire.com/svs-pb-2000-review-3135027

http://www.audioholics.com/subwoofe...0/measurements

Sometimes, we are the victims of our own lofty expectations. The PC4000 is a better subwoofer than the PC2000. It is stronger below 60Hz, even in the Extended mode, and stronger down to 20Hz, at every frequency in the Standard mode. (The Extended mode, with its lower port tune, is specifically designed to give you more SPL <20Hz.) The sound quality should be subjectively better, and it has more versatility. But, you may not find an in-your-face, night-and-day difference when you move-up to a more powerful subwoofer, within the same family of subs, the way you would if you went from a sealed subwoofer to a ported one. Just give yourself a little time with this. The PC4000 is a very good subwoofer.

Regards,
Mike
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post #4 of 15 Old 01-12-2019, 09:20 AM
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For what it’s worth when I ran REW to compare my dual pc-4000 (extended mode) against my dual pc-12+ (extended mode) in same locations they looked very similar with actually a little more extension for the pc12+s for whatever reason. Differences may be more noticeable on the low end closer to max output I imagine.

Also on one of the few published reviews of the pc-4000 with measurements (see link) from sound and vision the -3db point in extended was 17hz rather than the 15hz spec from SVS. Don’t know if that is relevant or not as SVS is usually spot on with specs but just throwing that out there.

http://www.soundandvision.com/conte...iew-test-bench
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post #5 of 15 Old 01-12-2019, 02:35 PM
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From Audioholics
PC2000 PB4000(3 port) Extended (should be nearly identical to the PC4000)
16hz 95.6 99.1 107.1
20hz 104.3 112.3 109.2
25hz 108.7 113.3 110.4
31.5hz 109.9 114.8 113.6
40hz 111.5 116.8 116.3
50hz 111.2 118.7 118
63hz 110.9 117.7 115.4
80hz 109.9 116.2 114.2

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post #6 of 15 Old 01-12-2019, 03:20 PM
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No offense to anyone, but I wonder sometimes if people are really reading what they are posting. First, the PC4000 is in its Extended (16Hz) mode with one port plugged. It is in Standard (20Hz) mode with all three ports open. It is in Sealed Mode with all three ports plugged. The PC2000, of course, only has one mode, with about a 22Hz port tune.

Second, there is no comparison at all to the CEA-2010 numbers for the PC4000 in either the Standard mode, or the Extended mode, to the PC2000. Audioholics reviewed and measured both subs (the PB4000 actually, but the results should be virtually identical) and the results are clearly illustrated in the links below. The PC4000 has a larger and more powerful driver, with more excursion; a larger cabinet volume; and a more powerful amplifier. And, it is clearly the more powerful subwoofer.

http://www.audioholics.com/subwoofe...r/measurements

http://www.audioholics.com/subwoofe...0/measurements

Regards,
Mike

Last edited by mthomas47; 01-12-2019 at 05:34 PM. Reason: Clarification
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post #7 of 15 Old 01-12-2019, 09:04 PM - Thread Starter
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OP here. I am not offended. But I am also sharing my direct, real life experience. And measurements. Not comparing theoretical results. Am I doing something wrong in my configuration or measurements? Perhaps. Even likely, since I am new to this. Thats why I shared my experience. And hopefully, the patient and generous guidance from more informed members here will guide me to a happy resolution, and serve as an informative post to others.
However I would also say paper stats only mean so much. I question if a PC4000 is twice the subwoofer a PC2000 is. Should it really cost more than 2x more? Is the PC4000 realoy equivalent to a PB4000? SVS marketing places it in the same category, and it has the same driver and woofer, but does not have identical performance. It doesnt reach as low (15hz vs 13hz Extended mode; 133 db vs 132 max
db spl per the manuals... similar but not identical).
Ive had the luxury of owning several expensive, powerful sports cars in my life. And Ive been beaten on the track by less powerful cars. So paper stats arent everything. Applied knowledge can go a long way, be it cars or subwoofers.
I do take issue with the cliam, or assumption, that PC4000 and PB4000 are virtually identical. There doesnt seem to be any hard data in a direct comparison by the same evaluators under the same conditions. I suspect the PB4000 consistently outperforms the PC4000 in all circumstances, thus making the PB4000 as a substitute slightly misleading.
Thanks to mthomas and confin and others I have some pointers to try. I will update accordingly. But I'll also be honest. A $799 to $1799 upgrade deserves nothing less.
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post #8 of 15 Old 01-12-2019, 09:30 PM
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Quote:
Originally Posted by RobZL1 View Post
OP here. I am not offended. But I am also sharing my direct, real life experience. And measurements. Not comparing theoretical results. Am I doing something wrong in my configuration or measurements? Perhaps. Even likely, since I am new to this. Thats why I shared my experience. And hopefully, the patient and generous guidance from more informed members here will guide me to a happy resolution, and serve as an informative post to others.
However I would also say paper stats only mean so much. I question if a PC4000 is twice the subwoofer a PC2000 is. Should it really cost more than 2x more? Is the PC4000 realoy equivalent to a PB4000? SVS marketing places it in the same category, and it has the same driver and woofer, but does not have identical performance. It doesnt reach as low (15hz vs 13hz Extended mode; 133 db vs 132 max
db spl per the manuals... similar but not identical).
Ive had the luxury of owning several expensive, powerful sports cars in my life. And Ive been beaten on the track by less powerful cars. So paper stats arent everything. Applied knowledge can go a long way, be it cars or subwoofers.
I do take issue with the cliam, or assumption, that PC4000 and PB4000 are virtually identical. There doesnt seem to be any hard data in a direct comparison by the same evaluators under the same conditions. I suspect the PB4000 consistently outperforms the PC4000 in all circumstances, thus making the PB4000 as a substitute slightly misleading.
Thanks to mthomas and confin and others I have some pointers to try. I will update accordingly. But I'll also be honest. A $799 to $1799 upgrade deserves nothing less.
Hi Rob,

I wasn't referring to you in my post. You are very welcome for any help, and I hope that some of it works for you. The PC4000 and the PB4000 should be virtually identical in performance, just as the PC and PB2000 are, and just as the PC and PB13 Ultra are.

Regards,
Mike
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post #9 of 15 Old 01-12-2019, 09:58 PM
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Quote:
Originally Posted by RobZL1 View Post
OP here. I am not offended. But I am also sharing my direct, real life experience. And measurements. Not comparing theoretical results. Am I doing something wrong in my configuration or measurements? Perhaps. Even likely, since I am new to this. Thats why I shared my experience. And hopefully, the patient and generous guidance from more informed members here will guide me to a happy resolution, and serve as an informative post to others.
However I would also say paper stats only mean so much. I question if a PC4000 is twice the subwoofer a PC2000 is. Should it really cost more than 2x more? Is the PC4000 realoy equivalent to a PB4000? SVS marketing places it in the same category, and it has the same driver and woofer, but does not have identical performance. It doesnt reach as low (15hz vs 13hz Extended mode; 133 db vs 132 max
db spl per the manuals... similar but not identical).
Ive had the luxury of owning several expensive, powerful sports cars in my life. And Ive been beaten on the track by less powerful cars. So paper stats arent everything. Applied knowledge can go a long way, be it cars or subwoofers.
I do take issue with the cliam, or assumption, that PC4000 and PB4000 are virtually identical. There doesnt seem to be any hard data in a direct comparison by the same evaluators under the same conditions. I suspect the PB4000 consistently outperforms the PC4000 in all circumstances, thus making the PB4000 as a substitute slightly misleading.
Thanks to mthomas and confin and others I have some pointers to try. I will update accordingly. But I'll also be honest. A $799 to $1799 upgrade deserves nothing less.
Hi Rob
I don't think Mike was referring to you!
edit* Mike beat me to it!


...I'm not exactly sure who Mike was referring to actually lol...I'm guessing Kini62??


@Kini62 was showing 3 different figures 1.PC-2000 2.PC-4000 in 3 port mode 3.PC-4000 in extended mode, and when he wrote
Quote:
should be nearly identical to the PC4000
I think he just meant the port tune should be about the same. I think its likely 1-2Hz lower - but that nit-picking.
I was told the PC-2000's port tune was around 17-18Hz. Audioholics review put it at 17Hz
Quote:
The tuning point looks to be around 17 Hz

http://www.audioholics.com/subwoofe...r/measurements




Rob, IMHO the problem is your graphs are really only showing the base response of your subwoofers in your room ,which will probably be fairly similar amongst any of the 16-18hz port-tune SVS subs.
The blue line shown in your REW graph for the PC-2000 is probably approaching its limits in the deep bass and would likely start to show some compression under 20Hz if you were to go another 5dB or so louder (distortion would also rise rapidly). Whereas the PC-4000 in Extended mode would likely be good for a 110dB+ sweep without compression.


Were you running into the limits of the PC-2000?
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post #10 of 15 Old 01-13-2019, 06:57 AM
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Quote:
Originally Posted by jamiebosco View Post
Hi Rob
I don't think Mike was referring to you!
edit* Mike beat me to it!


...I'm not exactly sure who Mike was referring to actually lol...I'm guessing Kini62??


@Kini62 was showing 3 different figures 1.PC-2000 2.PC-4000 in 3 port mode 3.PC-4000 in extended mode, and when he wrote I think he just meant the port tune should be about the same. I think its likely 1-2Hz lower - but that nit-picking.
I was told the PC-2000's port tune was around 17-18Hz. Audioholics review put it at 17Hz


http://www.audioholics.com/subwoofe...r/measurements




Rob, IMHO the problem is your graphs are really only showing the base response of your subwoofers in your room ,which will probably be fairly similar amongst any of the 16-18hz port-tune SVS subs.
The blue line shown in your REW graph for the PC-2000 is probably approaching its limits in the deep bass and would likely start to show some compression under 20Hz if you were to go another 5dB or so louder (distortion would also rise rapidly). Whereas the PC-4000 in Extended mode would likely be good for a 110dB+ sweep without compression.


Were you running into the limits of the PC-2000?
That's a good post, Jamie! I suppose that different people may define the port tune in different ways. I believe that SVS defines the post tune of the PC2000/PB2000 as a little above 20Hz. My understanding is that the port tune can be distinguished, on a graph, as the point at which the port(s) can no longer contribute to the output, and the driver acts as if it is in free air. The highest point, just before the beginning of that rapid downward trajectory (the point of the elbow), is typically taken to be the port tune.

If we use that method of determining the port tune of the PC2000, as the graph you shared illustrates, it is just a little above 20Hz. If we use a similar method of comparing the PC4000, the port tune of the Standard 20Hz mode would be quite close to that of the PC2000, at just a little above 20Hz, and the port tune of the 16Hz Extended mode, would be somewhere between 16 and 17Hz. That 4 to 5Hz difference is just as it should be, and corresponds closely with the design goals for the subwoofers.

I certainly respect the guys at Audioholics, but I think it would be very hard to conclude that the port tune of the PC2000 is 17 or 18Hz. However we define the port tune, though, with respect to the beginning of the downward curve, or at some arbitrary point a little below that, there would still be a difference of at least 4 or 5Hz, between the Extended mode of the PC4000, and the single tuning mode of the PC2000. I think that distinction is important because it relates directly to some of the performance difference below 20Hz.

Regards,
Mike
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post #11 of 15 Old 01-13-2019, 08:13 AM
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Quote:
Originally Posted by RobZL1 View Post
However I would also say paper stats only mean so much. I question if a PC4000 is twice the subwoofer a PC2000 is. Should it really cost more than 2x more? Is the PC4000 realoy equivalent to a PB4000? SVS marketing places it in the same category, and it has the same driver and woofer, but does not have identical performance. It doesnt reach as low (15hz vs 13hz Extended mode; 133 db vs 132 max
db spl per the manuals... similar but not identical).
.
After you do this for awhile one thing you appreciate is the cost of incremental upgrades, and that they get expensive as your gear gets better. I'm simplifying, but if you have a sub and you add and co locate a second you get an additional 6 db of output. If your sub costs $500, the additional 6db costs $500. If your sub costs $2500, an additional 6 db costs $2500, and that is probably a smaller improvement percentage - wise than the first!


In that light, the additional expense for better sub models generally will appear justified, but whether the expense is worth it is up to the consumer. If a lower or mid tier model will meet your needs, then generally there's little sense in paying more for something better.

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post #12 of 15 Old 01-13-2019, 02:03 PM
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Quote:
Originally Posted by mthomas47 View Post
That's a good post, Jamie! I suppose that different people may define the port tune in different ways. I believe that SVS defines the post tune of the PC2000/PB2000 as a little above 20Hz. My understanding is that the port tune can be distinguished, on a graph, as the point at which the port(s) can no longer contribute to the output, and the driver acts as if it is in free air. The highest point, just before the beginning of that rapid downward trajectory (the point of the elbow), is typically taken to be the port tune.

If we use that method of determining the port tune of the PC2000, as the graph you shared illustrates, it is just a little above 20Hz. If we use a similar method of comparing the PC4000, the port tune of the Standard 20Hz mode would be quite close to that of the PC2000, at just a little above 20Hz, and the port tune of the 16Hz Extended mode, would be somewhere between 16 and 17Hz. That 4 to 5Hz difference is just as it should be, and corresponds closely with the design goals for the subwoofers.

I certainly respect the guys at Audioholics, but I think it would be very hard to conclude that the port tune of the PC2000 is 17 or 18Hz. However we define the port tune, though, with respect to the beginning of the downward curve, or at some arbitrary point a little below that, there would still be a difference of at least 4 or 5Hz, between the Extended mode of the PC4000, and the single tuning mode of the PC2000. I think that distinction is important because it relates directly to some of the performance difference below 20Hz.

Regards,
Mike
Cheers Mike!
That's interesting, I've never heard that the PB-2000 / PC-2000 port tune was above 20Hz before, usually I've read they are in the 17-19Hz. range


So are you saying that port tune is actually around the point in the Frequency Response sweep where the response starts to drop off?


Can you explain why these other ported subs seem to start dropping off above their stated port tuning? (unless I'm misunderstanding/reading the graphs wrong)


Here's the PB-2000 full range frequency response



Here's the PB12-NSD with a claimed port tune around 20Hz





Here's the Basic Response for the PSA XV30FSE,I think it had a port tune around 20-22Hz (don't quote me on that though), but the downward curve starts around 30Hz


Here's the JTR 2400ULF ,which is stated to have a 10Hz port tune



Here's the JTR 4000ULF,again with a stated 10Hz port tune



The Rythmik FV18HP in 16Hz tune mode



The Rythmik FV25HP with what I think is a 12Hz port tune









What am I missing?
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post #13 of 15 Old 01-13-2019, 02:44 PM
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Originally Posted by jamiebosco View Post
Cheers Mike!
That's interesting, I've never heard that the PB-2000 / PC-2000 port tune was above 20Hz before, usually I've read they are in the 17-19Hz. range


So are you saying that port tune is actually around the point in the Frequency Response sweep where the response starts to drop off?


Can you explain why these other ported subs seem to start dropping off above their stated port tuning? (unless I'm misunderstanding/reading the graphs wrong)


Here's the PB-2000 full range frequency response



Here's the PB12-NSD with a claimed port tune around 20Hz





Here's the Basic Response for the PSA XV30FSE,I think it had a port tune around 20-22Hz (don't quote me on that though), but the downward curve starts around 30Hz


Here's the JTR 2400ULF ,which is stated to have a 10Hz port tune



Here's the JTR 4000ULF,again with a stated 10Hz port tune



The Rythmik FV18HP in 16Hz tune mode



The Rythmik FV25HP with what I think is a 12Hz port tune


What am I missing?
Hi Jamie,

That's an impressive collection of graphs. I don't know that you are missing anything, except that claimed port tunes may be sort of meaningless. Different sub makers apportion their DSP differently to create different FR shapes in a way that makes it very difficult to determine actual port tunes. Irrespective of port tune, look at the difference in the shape of the FR's between the PSA sub and the JTR's subs, for instance. It's pretty hard to draw any clear conclusions about port tunes from those.

But, the point I was originally making with the PC4000 is that, if you compare the "20Hz" port tune of the Standard mode with the port tune of the PB2000, you will see that they start to slope-off at almost exactly the same point. If you then look at any graph of the PB or PC4000, in Extended mode, you will see that there is about 4 or 5db difference in the point where the slope begins, compared to that same 20Hz port tune.

I'm honestly not sure how to determine a subwoofer's actual port tune except by the shape of the frequency response. Where the port stops pressurizing the cabinet, and the driver is acting as if its in free air, the frequency response will drop. That can happen either a little above or below the purported port tune in some cases. But, where the drop-off is precipitous (even with DSP) I think that we have to conclude that the ports are no longer contributing to the SPL. And, as I understand it, that's the definition of a port tune.

In any event, when we are discussing SVS subs, where the fundamental shape of the port tune is very similar in all of the ported models, I think that we need to compare the port tunes, based on their visible drop-off. And, if we do that, there is a difference of 4 or 5db between the PC2000 and the PC4000, whatever the actual port tune numbers may be. That would mean that, if the PC2000, and the PC4000 in Standard mode, has a 17Hz or 18Hz port tune, then the Extended mode has about a 13Hz port tune.

Of course, I don't believe that. I think that the PC4000 and the PB16 both have port tunes of about 16 or 17Hz. However, I also think that port tunes may be one of the last bastions of manufacturer exaggeration, in some cases, when they happen to list a port tune at all. Some sub makers don't list port tunes to begin with. Perhaps I am the one missing something here, but that's about the most sense that I can make of the "claimed" port tunes shown in your post.

Regards,
Mike

Last edited by mthomas47; 01-13-2019 at 02:51 PM.
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post #14 of 15 Old 01-13-2019, 04:20 PM
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Originally Posted by mthomas47 View Post
Hi Jamie,


But, the point I was originally making with the PC4000 is that, if you compare the "20Hz" port tune of the Standard mode with the port tune of the PB2000, you will see that they start to slope-off at almost exactly the same point. If you then look at any graph of the PB or PC4000, in Extended mode, you will see that there is about 4 or 5db difference in the point where the slope begins, compared to that same 20Hz port tune.


In any event, when we are discussing SVS subs, where the fundamental shape of the port tune is very similar in all of the ported models, I think that we need to compare the port tunes, based on their visible drop-off. And, if we do that, there is a difference of 4 or 5db between the PC2000 and the PC4000, whatever the actual port tune numbers may be. That would mean that, if the PC2000, and the PC4000 in Standard mode, has a 17Hz or 18Hz port tune, then the Extended mode has about a 13Hz port tune.

Of course, I don't believe that. I think that the PC4000 and the PB16 both have port tunes of about 16 or 17Hz. However, I also think that port tunes may be one of the last bastions of manufacturer exaggeration, in some cases, when they happen to list a port tune at all. Some sub makers don't list port tunes to begin with. Perhaps I am the one missing something here, but that's about the most sense that I can make of the "claimed" port tunes shown in your post.

Regards,
Mike

No Mike, It sounds like you have a pretty good understanding of this stuff. I find it really interesting!






Here's the PC13 Ultra, I added the line around where 20hz is (and quite poorly too I might add!)


In "20Hz" mode it has rolled off quite a bit before it actually hits 20Hz and in "16Hz" mode I would say it's pretty flat to 20hz and rolling off from there
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post #15 of 15 Old 01-13-2019, 04:54 PM
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Unless you have a measurement pre dsp it will be hard to find the exact port tune. The PB12 nsd is using a 4th order BW 48db which why it shows like a drop off a cliff. JTR looks like 2nd order BW 12 db. 2nd order will start rolling off slowly before its implementation.

Its a juggling act, do you want that last bit of extension or all the spl you can get before the driver goes into distress
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