Rythmik L12 Subwoofer Review

[Poseidons Voice]

Amir,

My reference standard for subwoofer measurements is Josh Ricci’s Databass website. I strongly suggest you peruse his website to see what he measures and why. In particular, SPL compression testing is incredibly important while carefully keeping an eye on THD at various SPL levels that are materially important (90-120dB). You will suddenly separate the wheat from the chaff. Some of the finer subwoofer manufacturers have started doing IMD measurements as well to distinguish how the subwoofer performs playing 2 or 3 or X different frequencies while playing at X SPL level.

As you already know, frequency response curves only confirm or discredit manufacturers’ claims since the room swamps those differences. Modal issues are best addressed first by multiple low frequency sources asymmetrically distributed around the room.

Have fun on this new venture!

Best,
Anand.

 

[edechamps]

I had originally hoped to develop full suite of tests for subwoofers. I don't have the luxury of time right now to do that so what follows is brief. Open to feedback on what else should be measured.

Well, the current standard for measuring subwoofers is CTA-2010, so I would suggest looking into that.

Not sure it's worth spending the time doing subwoofer reviews without max output/compression/distortion tests. Until a procedure for testing these is devised, I would suggest sticking to normal speaker reviews. When it comes to subwoofers, frequency response is useful but not the main criteria.

It's impressive to see how the NFS can completely eliminate room effects from the measurements though If anything this review serves as an additional data point to validate NFS performance in the low bass range.

 

[Mnyb]

I managed to get a rhytmic sub sent to Sweden , just contact them i bougth mine last year .

 

[MZKM]

If anything this review serves as an additional data point to validate NFS performance in the low bass range.

At least with a sealed enclosure.

 

[Bhh]

I believe Amir had more thorough battery of tests planned but unfortunately I need the sub returned soon as the home audition/return window is closing and I‘d like to test at home and return or pick up a second one before any more supply chain disruptions if this first one works out.

Everyone can direct their complaints about insufficient tests at me.

 

[igufi]

I managed to get a rhytmic sub sent to Sweden , just contact them i bougth mine last year .

Can you share how much you had to pay for the shipping?

 

[Hidde]

Since to see companies using motional feedback in sealed enclosures (as it should be).
Does the system use digital feedback and is the amplifier current driven? Current drive in combination with servo's always lead to very nice results for subwoofers!

 

[Ron Texas]

I have a pair of L12's to compliment my LS50's and am loving them. While I have not put them on a scale, I think they weigh about 42 lbs based on a UPS shipping weight of 49 lbs.

 

[Mnyb]

Can you share how much you had to pay for the shipping?

I'll check if i have the mail corrospondance left , but its was a substantial cost and import fee and taxes , but thier subs are so cheap that it still better than a REL for the same cost bougth locally upp the price 40% or so , however we do have 25% VAT in Sweden

 

[igufi]

I'll check if i have the mail corrospondance left , but its was a substantial cost and import fee and taxes , but thier subs are so cheap that it still better than a REL for the same cost bougth locally upp the price 40% or so , however we do have 25% VAT in Sweden

If you can find the details, that would be great - I live in Finland so I would expect the overhead costs of shipping, import fees and VAT to be pretty similar.

 

[SmackDaddies]

Excellent, now bring on some big players like REL and SVS but also would love to see you measure our UK manufactured BK subs which are a big hit on the forums

Send him one. He is happy to test submissions

 

[Deleted member 2944]

Since to see companies using motional feedback in sealed enclosures (as it should be).
Does the system use digital feedback and is the amplifier current driven?

No and no.

The amplifiers are sourced from a manufacturer and then a daughter card added to implement the servo within the existing circuitry. The transducer has a small voltage feedback coil to provide the servo input, and there is also a small value resistor in series with the woofers driven coil (which is monitored across) to provide another input to the servo.

Brian Ding considers the specifics of all this proprietary. Suffice it to say, there's nothing fancy going on here at all. The concept is ages old.

Dave.

 

[RayDunzl]

Can you share how much you had to pay for the shipping?

I'm reminded of this (unrelated) old story:

https://about.usps.com/who-we-are/postal-history/bank-of-vernal.pdf

 

[Olli]

Shipping 2 F18s to Germany was 350 USD total.

 

[Piotr]

Shipping 2 F18s to Germany was 350 USD total.

Well then I'd probably go with https://jblpro.com/en/products/lsr310s

Anyone has experienced jbl subs?

 

[Bhh]

Seems like someone filling up a container of these (and various other audio products) and shipping it to the “European Distributer” might not be a bad idea.

What makes up the huge weight discrepancy between these subs of the same driver size? Is it all cabinet design? With a 58lb shipping weight, the L12 must weigh-in around high 40s-50# while the SVS SB-1000 which is at a similar price point weighs 27 pounds. Where is all that extra weight coming from?

 

[RayDunzl]

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.

The speaker cone should move as the signal dictates.

Maybe that's all you're asking. Not sure.

The wave it produces in the air will be something different.

Here's a 10Hz square (though with full bandwidth at the speaker) I recorded in the past. Only the first 12ms of the 100ms wave cycle is shown, the negative half looks the same, but inverted.

I'm thinking a sealed woofer in a (tiny?) sealed room might hold the pressure for a square, but a vented speaker or our vented rooms won't.

---

The speakers "measure" well enough to below 10hz using a sine excitement:

(no smoothing, at the listening position)

---

The original measurement with the 10Hz square signal was to simulate step response, not to create an audible square:

https://www.audiosciencereview.com/forum/index.php?threads/impulse-response.1765/#post-44440

 

[ttZk]

Shipping 2 F18s to Germany was 350 USD total.

I assume that's shipping only, not including import taxes?

 

[Billy Budapest]

Excellent, now bring on some big players like REL and SVS but also would love to see you measure our UK manufactured BK subs which are a big hit on the forums

Right. BK are the original REL subs, or evolutionary versions of them, from before REL was bought by Sumiko, as BK was the OEM for REL.

 

[Ron Texas]

Seems like someone filling up a container of these (and various other audio products) and shipping it to the “European Distributer” might not be a bad idea.

What makes up the huge weight discrepancy between these subs of the same driver size? Is it all cabinet design? With a 58lb shipping weight, the L12 must weigh-in around high 40s-50# while the SVS SB-1000 which is at a similar price point weighs 27 pounds. Where is all that extra weight coming from?

UPS said the shipping weight was 49 lbs meaning the unit weighs 41 or 42 lbs. The difference is in thicker walls for the box, a much larger magnet and a thicker basket for the driver.