Official Rythmik Audio Subwoofer thread - Page 661 - AVS Forum | Home Theater Discussions And Reviews
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post #19801 of 19991 Old 07-17-2015, 12:15 PM
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In a large room, dual 15's is easily a noticeable improvement over a single.
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post #19802 of 19991 Old 07-17-2015, 12:17 PM
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I have a 15' x 20' home theater x 10' ceiling. Currently I have a 15" sealed Rhythmik sub with Revel F208's. The Rhythmik F15HP works great with music and very nice for movies. I would like a little more oomph for movies and would like a recommendation. I would need put the sub woofer on the side of the room because my screen is only 24" from the ground. (Does it matter that the sub will be firing from the side of the room?) If I went with Rythmik, would it be better to go with the ported FV15HP or the dual 15-inch driver sealed design (F25)? I don't have options on where to move the subwoofer and I know sometimes a 2nd sub doesn't add that much.
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post #19803 of 19991 Old 07-17-2015, 02:36 PM
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With 2 subs, the best placement is to have both of them opposite of each other. That means front and back walls, or both side walls. Corners work too but will sound a bit different.

You shouldn't mix ported and sealed for the best results. And since you already have one sealed 15" Rythmik, the choice is clear - get another one

Last edited by Soulburner; 07-17-2015 at 02:47 PM.
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post #19804 of 19991 Old 07-17-2015, 06:16 PM
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Quote:
Originally Posted by trmoore2 View Post
I have a 15' x 20' home theater x 10' ceiling. Currently I have a 15" sealed Rhythmik sub with Revel F208's. The Rhythmik F15HP works great with music and very nice for movies. I would like a little more oomph for movies and would like a recommendation. I would need put the sub woofer on the side of the room because my screen is only 24" from the ground. (Does it matter that the sub will be firing from the side of the room?) If I went with Rythmik, would it be better to go with the ported FV15HP or the dual 15-inch driver sealed design (F25)? I don't have options on where to move the subwoofer and I know sometimes a 2nd sub doesn't add that much.
If you haven't done so, carry out a sub crawl as shown in the following youtube video by Axiom Audio.

Once you've identified a few good places for the subs, place the Rythmik F15HP in the best location. You might want to carry out an in room measurement of the sub response using REW to check. A pair of the same subs will do much better than a single sub. In the sub world, two are always better than one for a number of reasons.
(1) It will smooth out the in room frequency response (peaks the troughs) and get a better seat to seat consistency at the Main Listening Position (MLP).
(2) Provide more headroom and more extension.
(3) Minimize localization when crossover frequency is set to high values.

Your Revel F208 has the lower frequency response of -3dB at 34Hz. This is okay with two channel music, but the story is very different for movies. For example, Edge of Tomorrow (EoT) has the opening scene with a 10Hz tone and the Revel F208 will struggle with reproducing this cleanly. There are other bass heavy movie soundtracks. You might want to consider implementing bass management and crossing over the F208's from say 60Hz to 70Hz (approximately 2x the F3) to the subs. Best to check with REW the distortion numbers for your F208 and pick the best crossover frequency.
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post #19805 of 19991 Old 07-17-2015, 07:56 PM
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Quote:
Originally Posted by wyld0 View Post
What settings are you running on your FVs? I have an FV15HP with volume at 1 o'clock, sub output is -7.5 and LFE output a -10dB and the last two notes chuffing is crazy loud even at -15 master volume. I'm trying to find the thread where another FV15HP owner says he breezed through it with no problems in 1 port mode.



For those who havewatched the movie, do you feel the LFE channel is"over-mixed"?. My impression is based on the dialogue and sound of the chopper whichthe heavy LFE makes the blade whirling sound very bloated.
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post #19806 of 19991 Old 07-17-2015, 11:45 PM
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These F12s have taken my movies to a whole new level. Now I now what people mean when they say "impact".

When the Kraken snaps the mast and takes the Black Pearl under, you feel the initial SNAP, then a shockwave ripples through the room and rumbles your seat. All very tight with high damping. No boom or drone. Good stuff!

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post #19807 of 19991 Old 07-18-2015, 04:02 AM
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I am not trying to spark any debate over brands, just looking for some advice. I posted a similar comment on PSA forum and know that each forum's users will be a bit biased. I am looking to replace my PC-Ultra with dual subs. I want to go sealed because of all the sealed advantages (tighter punchier bass). I narrowed my choices down to Rythmik and PSA and am trying to understand some differences. Th F15HP goes to 14HZ (-2DB) and the S1500 goes to 19Hz(-3db) with the rolloff looking like it starts around 30Hz (typical of sealed subs). Brian, Enrico and Tom have all been very helpful, but clearly biased toward their own products. I know the F15HP box is a little bigger and wondering if that and the servo are what allows it to get down to 14Hz. I do mostly HT, but will be expanding my music listening and do not want o give up those deep lows. I know the FV15HP has been said to be very musical, but that box is getting rather large. Sine the F15HP runs a bit more $$ and no free return shipping it would be a big risk to try it if it does not work out and I am not the type to do the free no risk PSA shipping unless I really plan on keeping it. The room is 15Wx20Dx8H with single 30 inch opening at the back near seating area. Any advice in helping me figure out what I am ove rlooking or not understanding would be greatly appreciated! Thanks!

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post #19808 of 19991 Old 07-18-2015, 09:41 AM
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If it is in the budget kluken have you considered the F25?
That model is sealed and sports dual 15" drivers with output that is close to the FV15HP.
Dimensions are rather close to the F15HP in respects to width and depth; clearly it is taller but gaining so much more.

I purchased a DIY 15" kit a few years ago and my only regret was not waiting a little longer and pay the extra for the HP amp. That or the FV15HP kit but finances did not allow for it and wanted a subwoofer up and running again in time for my b-day.

There are a great selection of subwoofers to choose from various companies and my experience with my Rythmik has been great, just that pesky upgrade bug wants more, and the feedback for SVS and HSU are also very positive.

For what it is worth, there have been very few individuals who have been dissatisfied to the extent that they spoke poorly of the product or returned it outside of a potential defect. Biggest complaint usually is those wishing they had gone with the FV15HP.

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post #19809 of 19991 Old 07-18-2015, 09:43 AM
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^^ start a new thread about the two subs you are shopping for. If you ask here, guess what I will recommend? Not because I am bias but it's hard to get another sub once you have Rythmik.

Last edited by tvuong; 07-18-2015 at 09:54 AM.
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post #19810 of 19991 Old 07-18-2015, 09:52 AM
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You are unlikely to hear the difference between -3 dB at 14 Hz or 19 Hz. You are more likely to hear the difference a good servo design offers in the way of cleaner bass. Chances are you would be happy with either sub. Back when I was researching, I decided I would be happier with Rythmik, but YMMV. - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #19811 of 19991 Old 07-18-2015, 11:47 AM
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Quote:
Originally Posted by enricoclaudio View Post
From Denon in order to get XT32 + SubEQ HT you have to look for "Audyssey Platinum" which is present on former model X4000 (discontinued), last year and still on production X4100W and newer model X4200W and up. From Marantz the SR7008 (the one I have) and SR7009 have XT32 + SubEQ HT as well. Below $1000 you can get a refurbished unit from Accesories4less with one year warranty or a new Marantz SR7008 (Amazon)

http://www.accessories4less.com/make...airplay/1.html

http://www.accessories4less.com/make...-150wpc/1.html

http://www.accessories4less.com/make...airplay/1.html

http://www.accessories4less.com/make...airplay/1.html
Ordered the 7008. Price was great and hopefully the free 3 year warranty is worth something. Gonna go ahead and pick up another FV also. The projector will just have to wait.

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post #19812 of 19991 Old 07-18-2015, 12:58 PM
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Originally Posted by tvuong View Post
^^ start a new thread about the two subs you are shopping for. If you ask here, guess what I will recommend? Not because I am bias but it's hard to get another sub once you have Rythmik.
That I knew, but I was looking for the Rythmik fans/owners to tell me if I was missing something or have they seen the F15HP deliver really goo deep tight lows. It was less about the comparison and more about vetting the claims of 14Hz out of a sealed sub and only being down 2db. Everything I have read is that the roll off of sealed subs starts around 30Hz, so I am struggling to see how 14Hz is only down 2db.

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post #19813 of 19991 Old 07-18-2015, 01:20 PM
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Originally Posted by kluken View Post
That I knew, but I was looking for the Rythmik fans/owners to tell me if I was missing something or have they seen the F15HP deliver really goo deep tight lows. It was less about the comparison and more about vetting the claims of 14Hz out of a sealed sub and only being down 2db. Everything I have read is that the roll off of sealed subs starts around 30Hz, so I am struggling to see how 14Hz is only down 2db.
Two things:

1. Sealed subs "roll off" slower than ported subs, so will often have more output in the teens where ported subs roll off rapidly

2. The servo helps quite a bit. This is a trick that other companies can't claim to have
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post #19814 of 19991 Old 07-18-2015, 01:24 PM
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The frequency response is a complex function of driver and enclosure parameters as well as the room in which it operates. I don't know where or what you read but it is wrong. There is nothing intrinsic to a sealed enclosure design that says it will roll off at 30 Hz. Or anywhere else; it is a function of the design (and room). There are plenty of sealed and ported subs that roll off above and below 30 Hz. One intrinsic characteristic is that a ported (vented) sub will roll off more rapidly below the port tuning frequency than a sealed sub so below the lower corner frequency a sealed sub will have a little more output than a ported sub. Above, a ported sub will have more output, all else being equal.

There are response curves on the Rythmik site.

In my room my pair of F12's go down to about 10 Hz.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #19815 of 19991 Old 07-18-2015, 07:35 PM
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Hi guys,

Just to let you know that Jim Wilson review of the Rythmik Audio F8 have been posted on Home Theater Shack!!

http://www.hometheatershack.com/foru...f8-review.html

Enjoy!!

Best Regards,

Enrico Castagnetti
Rythmik Audio

 

My Multimedia Room Gallery

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post #19816 of 19991 Old 07-18-2015, 09:31 PM
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I have 2 F12's and the get the most low frequency output what should the damping be on? Low, mid or high? My cutoff's are on 14 hz.

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post #19817 of 19991 Old 07-18-2015, 10:23 PM
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Originally Posted by falconxr6 View Post
I have 2 F12's and the get the most low frequency output what should the damping be on? Low, mid or high? My cutoff's are on 14 hz.
If you're set to 14 you're already getting the lowest extension. Damping will affect the control of the driver and in turn how much definition you hear in the bass.
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post #19818 of 19991 Old 07-19-2015, 02:10 PM
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Originally Posted by kluken View Post
That I knew, but I was looking for the Rythmik fans/owners to tell me if I was missing something or have they seen the F15HP deliver really goo deep tight lows. It was less about the comparison and more about vetting the claims of 14Hz out of a sealed sub and only being down 2db. Everything I have read is that the roll off of sealed subs starts around 30Hz, so I am struggling to see how 14Hz is only down 2db.
First the disclaimer. Standard spec of frequency response is +3/-3db range. So the -2db is based on that spec, which is -5db from the top of the FR curve. But it is still better than almost all sealed subs Data-bass site has tested. For instance, one of the tested sub is down -16db at 14hz. Please note a lot of sealed subs without using this +3/-3db spec cannot claim that they have 20hz extension.

So now back to the answer to your question. As soul burner has pointed out, it is because of servo. That is the shorter version of the answer. The longer version of the answer is how servo 1) alters the frequency response, and 2) addresses the challenge of having low extension and still sound good (not boomy).

Servo controlled subs compare the servo feedback signal to the power amp input signal and then output more power if it finds the woofer does not move fast enough, or output reverse throttle when it finds woofer moves too fast. So it is not just one direction control. This help the subwoofer to actively reject external interference acted upon the woofer. For instance, the box spring is one of such external force. So is the internal standing wave of the enclosure. Servo will have much less value if it cannot be analyzed formally. Without that, servo will be used as a "patching", or trial-and-error, or an adhoc technique. In fact, in early days, servo design was done that way. One of the former Genesis engineers told me that was how Arnold did their servo design in their early servo subwoofers, trying a different resistor value or capacitor value at a time and see if the output was better.

So after formal analysis of servo control design, I have found it behaves like changing the T/S of the driver. The frequency response is just like real world sealed subwoofer (with large diameter driver and large motor) from top to bottom. This is very different from the result of using EQ to achieve extension becasue the amount of EQ will be enormous at the bottom end and the designer needs to do a cut-off point decision. That is one of the reason you have seen other nonservo sealed subwoofers cannot go -5db down at 14hz. It will be just too much EQ. Another very important capability of servo is that we can "clone" the frequency response. That is why you will see our sealed subs all have very similar extension curve regardless driver diameters. That is by design.

Second part of how servo can do better is related to this comment "best bass is no bass". You can say this is sarcasm. Making low extension actually expose the sound quality weakness of low bass. In time domain, reproducing a 10hz signal takes 4 times as long as that of a 40hz. If there is a ringing, the ringing at 10hz will last 4 times longer too. That means there are 4x more reason that the sound can be bad. So instead of exposing the subwoofers to that problem, many designers just cut back the extension to avoid problems. We allow our subwoofers to go that low because we are able to control the impulse response to almost no ringing. In our frequency response plot, we publish both amplitude and phase response curves. No other manufacturers do that. What we want to show is our sealed subwoofers have the minimal phase shift among all sealed subwoofers. For instance, our F15HP as about 100 degrees phase shift from the microphone. Now in reality is F15HP has even lower phase shift because we are able to calibrate microphone with our servo signal (yah, we can claim no other manufacturer can do that) and found our measurement grade microphone, which is flat down to sub 10hz, has 18 degrees phase shift at 20hz and 45 degrees phase shift at 10hz. An ideal sealed subwoofer has 2nd order roll-off, which has 90 degrees phase shift at the corner frequency. So our sealed subwoofers are not far from that ideal case. In addition, when the subwoofer is -14db down, you can expect the phase shift to 180 degrees or even more.

Some may challenge that while we have low extension, how much output can the subwoofer do, sort of hinting the extension is not useful at all. Real life sound does not have a lot of sub-sonic components. For instance, I have been observatory telescope dome. When I watch movies with similar scenes, what I want to hear is the reverberation is as realistically believable when the door is opened or when the dome is turn. That does not need a lot of subsonic energy. But it is important to align the subsonic signal (which is the reverberation) with the rest of the sound so that it sounds well integrated and believable. But any subwoofer with limited extension makes the dome sound smaller than what it is. Same thing is motorcycle throttle/exhaust noise. There are just too many examples. And lastly if the movies have too many artificial LFE signals that makes the sound boomy, we have rumble filter and other controls to cut back the extension.
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post #19819 of 19991 Old 07-19-2015, 04:56 PM
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Quote:
Originally Posted by kluken View Post
That I knew, but I was looking for the Rythmik fans/owners to tell me if I was missing something or have they seen the F15HP deliver really goo deep tight lows. It was less about the comparison and more about vetting the claims of 14Hz out of a sealed sub and only being down 2db. Everything I have read is that the roll off of sealed subs starts around 30Hz, so I am struggling to see how 14Hz is only down 2db.
While Brian has already responded using solid technical explanations why Rythmik's subs can do what they claim, I just wanted to add (as a customer) that I've measured in room (10x12) down to 10hz with a single L12. Using the Low-Music switch setting, I had an average level setting of 84dB from 10-200hz with a peak of 86dB around 23hz while 14hz was at 83dB. Qualitatively speaking, I can say that it's remarkably clean as well to reinforce what Brian was driving at with the "lack of ringing" paragraph. Whenever I now hear thunder off in the distance (not that I hadn't heard thunder before), I instantly associate it to my experience when I had 10-20hz tones going through the L12 for the first time. I had never experienced a sub that had that kind of LF acoustic energy before without what I now know to be smearing, sloppy distortion.

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post #19820 of 19991 Old 07-19-2015, 05:17 PM
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Originally Posted by 12B4A View Post
While Brian has already responded using solid technical explanations why Rythmik's subs can do what they claim, I just wanted to add (as a customer) that I've measured in room (10x12) down to 10hz with a single L12. Using the Low-Music switch setting, I had an average level setting of 84dB from 10-200hz with a peak of 86dB around 23hz while 14hz was at 83dB.
Now that is impressive. Show me another budget sub that can do that! Heck, even $$$ subs struggle with that!
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post #19821 of 19991 Old 07-19-2015, 05:20 PM
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12B4A and Rythmik (Brian),

Thank you both so very much as well as the others on here. It s funny as when I started this upgrade to my home theater I wanted to just get 2 new SVS PC-Ultras, then I decided I did not want the tall cylinders and looked at the PB-ultra, but the damn price was nuts so I started looking for alternatives. Of course then I went the sealed vs. ports route. I quickly narrowed my choices down HSU, PSA and Rythmik. Eliminated HSU and then the attraction of Tom at PSA was appealing, but I really like what I keep learning and reading about Rythmik and the servo.

In my modest 15Wx20Lx8H how much difference would the F15HP be from the FV15HP be? I read some of these blind tests that sealed vs. ported and people can't tell?

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post #19822 of 19991 Old 07-19-2015, 05:44 PM
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There's no good way to predict the response in your room as it depends upon placement and how loudly you like to play. Spec-wise an FV15HP offers about 5.5 dB more output, nearly twice as loud in the bass region, but that only matters if you actually need/want the extra output. The FV15HP will roll off faster than the F15, natch, and arguably have a bit higher distortion though the servo largely obviates that difference. Never any worry about port noise with a sealed sub, but frankly a (any) decent ported sub is only going to have audible port noise in very special cases (typically a tone hitting right at the or near the port frequency). Within their frequency and power range I really doubt anyone could tell if you had an F15, F15HP, or FV15HP. For my system, using planer magnetic speakers (Magnepans), low distortion and the ability to integrate cleanly with "fast" main speakers was paramount so Rythmik was an easy choice.

The first sub I owned, and last before Rythmik, was a home-brew servo sub of my own design. I couldn't afford commercial as a college kid, and frankly was not impressed with their sound. Interestingly enough, after a lot of research, the design I utilized was very similar to the Rythmik design. Brian has taken it further, naturally, and has modern drivers and electronics (and the patent, wish I had patented my design ).

FWIWFM - Don

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post #19823 of 19991 Old 07-19-2015, 05:46 PM
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The difference is that the FV15HP will be able to put out +5.5db more at 20Hz than the F15HP. It also gives you the option to plug one or two ports depending on your room and/or preferences.

According to the exhaustive research I did before making my purchase, you should not be able to tell a difference in sound quality between the two above the port tune frequency, especially with the servo.

Anyone have a different take?

The reason I went sealed (F12s) was due to their smaller size, getting all the benefits Rythmik has to offer yet not giving up too much over the bigger subs. I will never utilize 110db output. I can put small tables with plants over them for aesthetic/SAF reasons
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post #19824 of 19991 Old 07-19-2015, 06:20 PM
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I guess I need to figure out how ugh SPL I hit when I really crank my movies up. Once I di that I can make sure sealed would work.

Panasonic 65VT60
Denon x7200WA
Oppo BD-103
Klipsch RP-280F / RC-62ii / RS-35 / RS-25
SVS PC13-Ultra
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post #19825 of 19991 Old 07-19-2015, 06:20 PM
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Originally Posted by kluken View Post
12B4A and Rythmik (Brian),

Thank you both so very much as well as the others on here. It s funny as when I started this upgrade to my home theater I wanted to just get 2 new SVS PC-Ultras, then I decided I did not want the tall cylinders and looked at the PB-ultra, but the damn price was nuts so I started looking for alternatives. Of course then I went the sealed vs. ports route. I quickly narrowed my choices down HSU, PSA and Rythmik. Eliminated HSU and then the attraction of Tom at PSA was appealing, but I really like what I keep learning and reading about Rythmik and the servo.

In my modest 15Wx20Lx8H how much difference would the F15HP be from the FV15HP be? I read some of these blind tests that sealed vs. ported and people can't tell?
I had a typo in my previous post (what I meant was low extension, not low excursion, that makes the dome sound smaller).

My recommendation for customers has been very sensible. If you don't have strong opinion about sealed vs ported and is quite happy with the ported sub you have now (just want to get more articulation and musicality), then our FV15HP will be good choice. In one port mode with 14hz high damping, its phase shift, measured by group delay, is almost as good as nonservo sealed subs such as Paradigm Sub 2, which has similar extension as FV15HP. On the other hand, if a customer tells me he never likes ported subs, then there is no need to even convince him to try ported subs.
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post #19826 of 19991 Old 07-19-2015, 10:17 PM
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Originally Posted by kluken View Post
I guess I need to figure out how ugh SPL I hit when I really crank my movies up. Once I di that I can make sure sealed would work.
What is your normal listening volume and do you run your bass hot? Are you more into music or movie? Your room is 2400^3ft, so it's not that big. Is the room completely sealed off or open to other part of your house? Whatever you are buying, try to get a pair.
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post #19827 of 19991 Old 07-20-2015, 03:36 AM
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That I knew, but I was looking for the Rythmik fans/owners to tell me if I was missing something or have they seen the F15HP deliver really goo deep tight lows. It was less about the comparison and more about vetting the claims of 14Hz out of a sealed sub and only being down 2db. Everything I have read is that the roll off of sealed subs starts around 30Hz, so I am struggling to see how 14Hz is only down 2db.
EQ can shape the response to whatever one wants as long as you are below the subs maximum output capabilities. You can make any sealed sub flat to 10 Hz with eq at low SPL. It does not change at what level the sub will start to compress.
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post #19828 of 19991 Old 07-20-2015, 03:41 AM
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Originally Posted by Soulburner View Post

According to the exhaustive research I did before making my purchase, you should not be able to tell a difference in sound quality between the two above the port tune frequency, especially with the servo.

Anyone have a different take?
I think you are right on the money with this statement. There are plenty of people who prefer sealed subs because they buy into the notion that they are tighter or crisper or whatever, but blind testing has debunked this time and again. If Brian were to set up the FV15HP properly in a room and it was eq'd exactly the same as the F15HP, I would bet no one could reliably tell the difference between the two on music, especially if the knowledge of whether their preferred alignment was playing was withheld from them.
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post #19829 of 19991 Old 07-20-2015, 03:45 AM
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I guess I need to figure out how ugh SPL I hit when I really crank my movies up. Once I di that I can make sure sealed would work.
Your room is similar in size to mine. Yours is 2400 ft^3, mine is 2525(17x16.5x9). I get around 13 dB of room gain at 10 Hz, which means that my FR is completely flat down to 10 Hz with dual sealed subs with no eq applied at all. So whatever subs you buy should be able to reach your output requirements down low as long as they can do so in the 20-30Hz region. I don't think you will be able to tell a sound quality difference between good quality, well designed ported subs and good sealed subs. However, sealed subs will have better extension and more output at very low frequencies(below 12-15 Hz) compared to most ported subs. And you eliminate the possibility of any port noise or chuffing.....ever.

Last edited by bear123; 07-20-2015 at 03:50 AM.
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post #19830 of 19991 Old 07-20-2015, 03:56 AM
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Originally Posted by tvuong View Post
What is your normal listening volume and do you run your bass hot? Are you more into music or movie? Your room is 2400^3ft, so it's not that big. Is the room completely sealed off or open to other part of your house? Whatever you are buying, try to get a pair.
Room has a single 30 inch opening at the back near listening position. I tend to listen a tad loud, but never measured in detail. On the Denon I tend to watch movies at -10db on the volume, I tried my RS SPL meter last night set to slow response and MAX (holds highest reading over previous 1 second) and watching some heavy LFE parts of a movie with volume to -16db (gf was complaining ;-) ) I saw it get to 116 db (at MLP). I do run the sub about 6db hot. I do find that on my PC-Ultra the gain is just short of being halfway so I am clearly not pushing that amp. I do plan on getting a pair of whatever I select. My anal process is because I don't want to make a mistake and have to eat shipping both ways.

Panasonic 65VT60
Denon x7200WA
Oppo BD-103
Klipsch RP-280F / RC-62ii / RS-35 / RS-25
SVS PC13-Ultra

Last edited by kluken; 07-20-2015 at 04:03 AM.
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