Rythmik L12 Subwoofer Review

[Francis Vaughan]

My suggestion for a subwoofer measurement would be to test its ability to track a square wave at E0 (20.602Hz) at a reference level. How fast can it incline and decline, and can it hold steady at the top and bottom of the square? I think that's where you'll really see a big difference in engineering quality.

As others have implied, this is a useless and scientifically wrong approach to understanding a subwoofer. The speed at which it rises is governed by the bandwidth - which is necessarily confined by the low pass filter. Holding steady is a function of its x-max. In order to maintain a constant pressure the cone must move at a constant speed. So the sound pressure at which a constant pressure can be maintained is nothing more than a function of the desired pressure, the period of the signal and the driver's x-max.

To a large extent, unlike ordinary speakers, a subwoofer is characterisable by nothing more than the basic physical parameters of the driver and the box. The ubiquitous Thiele-Small parameters and the box alignment. What we are likely to see in most of the tests is a validation of the TS parameters and box design. Where it will get interesting is where it uncovers simple lies from the manufacturer: deficiencies in the amplification and filters, poor box construction, for vented boxes issues with things like vent noise, and maybe driver distortion.

To be useful a sub needs to have little to no output above its operating range, otherwise it starts to cause problems with localisation - that is you can localise it. Usually with a pretty steep (ie 4th order) crossover at 80Hz. Port noise, rattles, resonances and distortion products will be localised. Localisation of distortion products is an interesting issue, as that maybe more important than the perceptual influence of those products on the sound quality.

What it tells you is that you don't want the sub to reproduce much at all above the crossover frequency. Hence any idea of reproducing square waves is a really bad idea. It harks back to such nonsense as 'fast' bass.

 

[igufi]

@amirm Where is the panther?

 

[Mnyb]

As others have implied, this is a useless and scientifically wrong approach to understanding a subwoofer. The speed at which it rises is governed by the bandwidth - which is necessarily confined by the low pass filter. Holding steady is a function of its x-max. In order to maintain a constant pressure the cone must move at a constant speed. So the sound pressure at which a constant pressure can be maintained is nothing more than a function of the desired pressure, the period of the signal and the driver's x-max.

To a large extent, unlike ordinary speakers, a subwoofer is characterisable to a very large extent by nothing more than the basic physical parameters of the driver and the box. The ubiquitous Thiele-Small parameters and the box alignment. What we are likely to see in most of the tests is a validation of the TS parameters and box. Where it will get interesting is where it uncovers simple lies from the manufacturer, deficiencies in the amplification and filters, poor box construction, for vented boxes issues with things like vent noise, and maybe driver distortion.

To be useful a sub needs to have little to no output above its operating range, otherwise it starts to cause problems with localisation - that is you can localise it. Usually a pretty steep (ie 4th order) crossover at 80Hz. Port noise, rattles, resonances and distortion products will be localised. Localisation of distortion products is an interesting issue, as that maybe more important than the perceptual influence of those products have on the sound quality.

What is tells you is that you don't want the sub to reproduce much at all above the crossover frequency. Hence any idea of reproducing square waves is a really bad idea. It harks back to such nonsense as 'fast' bass.

is it a question of Q of the whole system ? , I have a different rhytmic sub a larger 15" bassreflex and it's a knob for this called damping .

it is popular in speaker design and sub design to chose a to high Q value thus underdamp the design , bass sounds "fatter" correct bass can be to tight and lean ? not my pow but speaker desgners have made such choices .

So a normal Q=0.5 or adjustable to taste rhytmic can do this and it's probaly the real question behind much of the "fast bass" talk ? to high Q and the subwoofer will sound more and fatter but also ring and ripple ?

 

[MZKM]

Open to feedback on what else should be measured.

CEA-2010

Here is it for the Rythmik F18:

Data-Bass is the best website for subwoofer measurements IMO, here is the full measurement suite for the F18.

Group Delay is also highly welcome, this in part will tell us how “musical” a subwoofer is, Rythmik F18’s:

 

[somebodyelse]

Where can I buy it in Europe?

I planning to get one sub and thinking about JBL LSR310S / SB12-NSD. If I could get Rythmic L12 in $550 in price point EU it would be great.

They don't list a European distributor, and don't ship assembled subs internationally. You can get the kit version (plate amp and driver) and use the downloadable cabinet designs. You'll have to specify the carrier too, after finding one whose shipping fees you'll accept. It doesn't look like that amp version is available separately either - it's similar but missing the PEQ.
http://www.rythmikaudio.com/order.html
http://www.rythmikaudio.com/products2.html

 

[MZKM]

There is an odd feature, or at least oddly labeled, is the "bass extension." Setting it to Low Music (I think) provides deepest bass. The second setting, Low-HT, puts in a subsonic filter. The third one, "high," is some kind of power saving feature???

Manual stated High is for most output (>25Hz), comparison on their site:

 

[MZKM]

Wow thanks for kicking off subwoofers with the -to me- most interesting brand. To me, the most important thing about a subwoofer for music is the speed at which it can respond.

My suggestion for a subwoofer measurement would be to test its ability to track a square wave at E0 (20.602Hz) at a reference level. How fast can it incline and decline, and can it hold steady at the top and bottom of the square? I think that's where you'll really see a big difference in engineering quality.

Group Delay tells us how “quick” a subwoofer is.

 

[Koeitje]

Or he could simply google "room gain" and spared himself from the effort of proving something that has been known for at least 70 years.

You don't blast 110+dB at 20hz indoors and still be able to properly measure frequency response at very high output levels.

 

[QMuse]

You don't blast 110+dB indoors and still be able to properly measure frequency response at very high output levels.

Frequency response measured in open space won't be the same as the one measured in-room as with room gain sub will need to produce lower SPL to reach 110dB hence compression effect will be smaller.

 

[MZKM]

@amirm It’s Rythmik, not Rythmic.

 

[QMuse]

@amirm It’s Rythmik, not Rythmic.

Now you spoiled his rhythm!

 

[Koeitje]

Frequency response measured in open space won't be the same as the one measured in-room as with room gain sub will need to produce lower SPL to reach 110dB hence compression effect will be smaller.

Its about reaching the limits of the subwoofer and see how it performs. So with room gain you just get even more SPL inside

 

[QMuse]

Its about reaching the limits of the subwoofer and see how it performs. So with room gain you just get even more SPL inside

Sure. How about you open a new thread and show us some measurements of your system so we can see how you did sub integration?

 

[Koeitje]

Sure. How about you open a new thread and show us some measurements of your system so we can see how you did sub integration?

Sub integration has nothing to do with properly measuring subwoofer output. I am not interested in the room gain in Amir garage...

 

[Frank Dernie]

Data-Bass is the best website for subwoofer measurements IMO

Probably this is because of size and weight but almost none of the ones on their site are available here.
The normal speakers are bad enough, what is fashionable/easily available/cheap in one country may well not even be available in another, never mind fashionable and cheap!

 

[QMuse]

Sub integration has nothing to do with properly measuring subwoofer output. I am not interested in the room gain in Amir garage...

I was talking about measurement of in-room response of your mains+sub. That is something I would like to see after everything you said.

 

[Koeitje]

I was talking about measurement of in-room response of your mains+sub. That is something I would like to see after everything you said.

Why does it matter? It doesn't change my argument.

 

[QMuse]

Why does it matter? It doesn't change my argument.

Ok, all clear now - enjoy your music.

 

[Frank Dernie]

Where can I buy it in Europe?

I planning to get one sub and thinking about JBL LSR310S / SB12-NSD. If I could get Rythmic L12 in $550 in price point EU it would be great.

Given the size and weight of subs I doubt US made modestly priced subs will be competitive here, and even the expensive ones tend to have too high a price compared to US prices, probably because of this.
Equally, European subs probably aren't good value in the US and probably won't be tested by Amir because of availability.

 

[Koeitje]

Ok, all clear now - enjoy your music.

Well, that proves it. You have idea what you are talking about and don't understand why you don't want data about how a subwoofer performs in a room for a review.