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Rythmik L12 Subwoofer Review

jeffhenning

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Why would the crossover need to be lower?

There is nothing stating you can’t make a “musical” ported sub. In fact, most ported subs have less distortion. The SVS PB-12NSD as an example not only has far less distortion than the SB-12NSD, it also has quicker decay, so more musical all around.

Unless due to space constraints, after a certain price point, I see no reason not to choose a well design ported sub over a sealed one

The FV18 starts rolling off around 75-80HZ going up in frequency. The ideal crossover for the LS50 is around 170Hz. That big driver just can't make it that high.

As to ported designs having less distortion, that is only going to be around their port resonance. Somewhere below one octave above the port resonance, you will begin to get the benefit of the ported design. Above that, there is no benefit at all.

A ported sub can play louder, lower with less THD than a comparative sealed design around its port frequency, but you are aren't getting that for free. At the port resonance, the bass being produced is 360° out of phase with the upper octaves. As you get more output from the port, the more you hear that delayed bass signal. For an active sub, the phase response will be worse since there has to be a steep high pass filter to keep lower frequencies from causing the woofer to bottom out or being destroyed all together. Going down, ported designs unload the woofer of the back pressure caused by the cabinet and port. Any substantial signals below the port frequency can damage the driver.

You get more bass with less distortion on the bottom octave, but the cabinet is much larger and the temporal response is total crap.

Using a greater number of sealed subs, you get as ideal a temporal response as possible. The multiple subs increase headroom. Finally, multiple subs will allow you to place them in the room where they will produce the smoothest bass response in the listening area. One huge sub can't do that. It's in-room response will be compromised.

And, let's not forget, in both cases, we're talking about servo subs so "distortion" isn't really a very large factor for either unless you are talking about "Metallica" SPL's.

After getting them fairly dialed in, I've found my four L12's to be as good as any subs I've ever heard. They also produce a much cleaner low B from my 5 string than any bass amp.

A half dozen FV18's in a dance club would be incredibly potent and sound better than any PA subs on the market. If, on the other hand, you are looking for great bass in a room of 500 sq. ft. or smaller, four or six much smaller, sealed servo subs will give you everything you want and then some.

This is not my opinion. It's scientific fact that's been known for decades.
 

MZKM

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The FV18 starts rolling off around 75-80HZ going up in frequency

It can go flat up to 200Hz, it just depends if you have it in LFE or Line-in mode. It also has a rumble filter, specifically made for the Edge of Tomorrow opening. Any delayed output (or “total crap” temporal response) would show up in time domain related graphs, the spectrogram and group delay of the FV18 are fine, the group delay isn’t as good as the F18, but it’s still below 1 cycle, thus inaudible.
 
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jeffhenning

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It can go flat up to 200Hz, it just depends if you have it in LFE or Line-in mode. It also has a rumble filter, specifically made for the Edge of Tomorrow opening. Any delayed output (or “total crap” temporal response) would show up in time domain related graphs, the spectrogram and group delay of the FV18 are fine, the group delay isn’t as good as the F18, but it’s still below 1 cycle, thus inaudible.

If you look, at their chart, the phase response is 360° out of phase around 15Hz and 180° out of phase at 20hz. This most likely would be phase response of the cone and not the more complex some of the one and ports.

A ported design can never have the port in perfect phase with the cone. It will always be 360° out of phase. That is the way they work.

If you like gigantic subs with crap temporal response, fine. I, on the other hand, do not.
 

jeffhenning

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I've grown tired of trying to school you dimwits on the differences of woofer designs.

The only woofer design that has minimal group delay is either sealed or dipole. Ported designs are not even close when it comes to temporal distortion.

One other thing that has not been brought up is port noise ("chuffing", "hooting", etc.). A passive radiator eliminates the port noise, but, unfortunately, it does tend to have a bit of ringing. Under most circumstances that isn't noticeable, but, again, there is no free lunch.

If all you care about is low end output, yes, a ported design works best for pure output above anything else.

If you want fidelity, a ported design falls short. This has been known for decades. If you don't know it, well...

For the least distortion and least group delay, either a sealed or dipole sub is the best. You will need to use more drivers and power to get the low end headroom needed to produce a low B of a bass or even lower, but it will sound incredibly clean. In fact, nothing will surpass it. Sorry, if you don't know that.

If you are talking about huge pipe organs or movie effects that go to or below 20Hz, under any circumstances, to play those signals cleanly you need a lot of air being displaced. To do that, there is no substitute for a lot of woofers of any design.

Honestly, I'm done with this thread. Have a nice life.
 

Senior NEET Engineer

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I've grown tired of trying to school you dimwits on the differences of woofer designs.

The only woofer design that has minimal group delay is either sealed or dipole. Ported designs are not even close when it comes to temporal distortion.

One other thing that has not been brought up is port noise ("chuffing", "hooting", etc.). A passive radiator eliminates the port noise, but, unfortunately, it does tend to have a bit of ringing. Under most circumstances that isn't noticeable, but, again, there is no free lunch.

If all you care about is low end output, yes, a ported design works best for pure output above anything else.

If you want fidelity, a ported design falls short. This has been known for decades. If you don't know it, well...

For the least distortion and least group delay, either a sealed or dipole sub is the best. You will need to use more drivers and power to get the low end headroom needed to produce a low B of a bass or even lower, but it will sound incredibly clean. In fact, nothing will surpass it. Sorry, if you don't know that.

If you are talking about huge pipe organs or movie effects that go to or below 20Hz, under any circumstances, to play those signals cleanly you need a lot of air being displaced. To do that, there is no substitute for a lot of woofers of any design.

Honestly, I'm done with this thread. Have a nice life.

I am sorry that your ego has been damaged.
 
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Bear123

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Unless you need to cross really high due to very incapable mains, a well designed sealed sub will sound just as good as a well designed ported sub i.e. Rythmik F18 vs Rythmik FV18, until the sealed sub runs out of headroom and starts to distort. At this point, the ported sub will obviously provide better sound quality. Group delay is a non issue in modern day, well designed, low tune ported subs. I'm not concerned about group delay at 12 Hz when listening to music, which has no content anywhere near that low.

Having said that, I use sealed subs as I don't want to accommodate the much larger cab size of ported subs, and I am willing to live with the decreased performance. But I don't pretend that my sound quality is somehow superior because I use sealed subs vs well designed, low tuned ported subs. It's just not true. A cheap crappy 40 Hz tuned ported sub? Sure, not high fidelity.
 
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Alice of Old Vincennes

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I've grown tired of trying to school you dimwits on the differences of woofer designs.

The only woofer design that has minimal group delay is either sealed or dipole. Ported designs are not even close when it comes to temporal distortion.

One other thing that has not been brought up is port noise ("chuffing", "hooting", etc.). A passive radiator eliminates the port noise, but, unfortunately, it does tend to have a bit of ringing. Under most circumstances that isn't noticeable, but, again, there is no free lunch.

If all you care about is low end output, yes, a ported design works best for pure output above anything else.

If you want fidelity, a ported design falls short. This has been known for decades. If you don't know it, well...

For the least distortion and least group delay, either a sealed or dipole sub is the best. You will need to use more drivers and power to get the low end headroom needed to produce a low B of a bass or even lower, but it will sound incredibly clean. In fact, nothing will surpass it. Sorry, if you don't know that.

If you are talking about huge pipe organs or movie effects that go to or below 20Hz, under any circumstances, to play those signals cleanly you need a lot of air being displaced. To do that, there is no substitute for a lot of woofers of any design.

Honestly, I'm done with this thread. Have a nice life.[/QUOT
 

Kvalsvoll

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Have there been blind tests of sealed vs ported subs?

Yes, I recall reading one on avsforum. Long time ago, so I do not remember all details, but they had several different subwoofers set up for blind listening, some sealed, some ported. They were asked whether they believed the sub was sealed or ported, and the answers showed no correlation. they also did not show preference towards sealed or ported. Which makes sense, from a technical point of view - it is the quality of the subwoofer design that determines the end result, not the acoustic principle.
 

Alice of Old Vincennes

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Geee, if only we all were as smart as you. That must be why a $20,000 speaker ports the woofer. Must be either to save money or appeal to teenage baseheads. No, it must be that a subwoofer Is "different" than a woofer.
 

DonH56

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Does this not imply that to set up Dirac properly I should use the L12's LFE input?

It is not a requirement but that is the normal way to connect to a sub to a component that has room correction. So my short answer would be "yes".
 
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