DIY Rythmik Audio Direct Servo 12" sealed 56L

[Ilkka]

Manufacturer: DIY/Rythmik Audio
Provided by: Ilkka
Manufacturer link: Rythmik Audio
Price: ~750 EUR

Manufacturer specs:
• Woofer: Rythmik Audio DS12TC
• Rigid anodized aluminum cone (black or silver)
• Rigid 12 spoke cast aluminum basket
• FEA designed aluminum short circuit ring to reduce 2nd order distortion
• High linear excursion capability of 1.4" peak to peak (xmax)
• High mechanical excursion capability of 2.6" peak to peak (xmech) to reduce risk of bottoming
• Very low inductance
• 24 ohm ultra thin sensing coil for servo operation keeps moving mass low
• Woven wire lead in the spider to prevent rattling during high excursion
• Gold spring loaded terminals for easy solderless cable connection
• Single 2.8 ohm voice coil
• Available with rubber mounting gasket (12-9/16" outer diameter and 3/4" depth)
• Mounting without gasket (12-3/8" outer diameter and 3/8" depth)
• Two 1" stacked magnets for a total magnet height of 2"
• 350W RMS max power
• Proudly made in USA
• Amplifier: Rythmik Audio A370 Direct Servo amplifier
• Output Power (4ohms): 350W RMS
• Op amps: OPA2134/TL072
• Power amp inputs: MOSFETs
• Subwoofer roll-off: 12 or 24 dB (not selectable)
• Power filter caps: 4x100V/6800uF
• Warranty: 2yr
• Enclosure: 56 liters (2 cubic feet), 19 mm MDF (double front baffle), braced

Configuration as tested:
Phase: 0 degrees
Crossover: Max
Extension filter: Hi-damping (Q=0.6), 14 Hz extension
Orientation: Woofer facing the mic

[Ilkka]

+/- 3 dB points: 12.5 Hz - 109 Hz

[Ilkka]

[Ilkka]

[Ilkka]

[Ilkka]

[Ilkka]

Reserved

[russ.will]

Ilkka,

I'm particularly interested in your thoughts on the Rythmiks especially now I see you've expended some of your own hard earned on one. I presume you wanted to test the water yourself?

As a Monolith owner in a 1500ft^3 room (potentially about to step up to a 2500ft^3 room), Im interested in something that will at least maintain current SPL levels whilst offering deeper extension and keep a lid on distortion. In the smaller Euro room (and given the current exchange rates) the Servos look like good value, but I'm having trouble penetrating the (admittedly short of SVS levels) of hyperbole on the website.

I was leaning toward the 15" servo kit in a 3-4 cu ft sealed box as the dual 12" would just be too large at 6ft^3. I read your results, add on the min claimed boost of 3dB, add on the room gain 6-12dB/octave and I'm arriving at some scarcely believable potential in room figures considering the power outputs of the amps and the power requirements of a sealed box.

Anybody's thoughts are welcome for that matter.

Russell

[bone215]

I, also, would like to read more about the sub and how it sounds.
Thanks.

[Ilkka]

russ.will wrote:

Ilkka,

I'm particularly interested in your thoughts on the Rythmiks especially now I see you've expended some of your own hard earned on one. I presume you wanted to test the water yourself?

As a Monolith owner in a 1500ft^3 room (potentially about to step up to a 2500ft^3 room), Im interested in something that will at least maintain current SPL levels whilst offering deeper extension and keep a lid on distortion. In the smaller Euro room (and given the current exchange rates) the Servos look like good value, but I'm having trouble penetrating the (admittedly short of SVS levels) of hyperbole on the website.

I was leaning toward the 15" servo kit in a 3-4 cu ft sealed box as the dual 12" would just be too large at 6ft^3. I read your results, add on the min claimed boost of 3dB, add on the room gain 6-12dB/octave and I'm arriving at some scarcely believable potential in room figures considering the power outputs of the amps and the power requirements of a sealed box.

Anybodies thoughts are welcome for that matter.

Russell

Hi Russel and Bone,

The 12" sealed Rythmik Audio DS is generally a really good subwoofer. It has versatile settings for extension and shape of the frequency response, which both help to match the subwoofer and the room. I don't want to say a lot of subjective comments about its sound because the listening room and personal preference affect a lot to it. I can say that its sound is slightly drier than what we usually hear with other subwoofers. That might be a good or bad thing, depending what kind of sound one likes. The upper end stays really clean even when pushed really hard, but when listening to material with lots of high amplitude low frequencies (HT use), you will start to hear some amp clipping noises (ticking, crackling) at certain point. In my small room this was around 102-105 dBC measured around 2.5 meters from the subwoofer. The subwoofer will still go louder, but not without these noises. They can be hard to hear when other speakers are blasting, but if you turn them off, you will notice when the subwoofer starts to overload. Brian decided not to use any amp limiters, which helps to preserve the maximum dynamic capability of the amp. But as you can see from the THD graph, distortion grows pretty large below 30 - 40 Hz when pushed hard. If one is using one of the lesser extension settings, naturally the low end compression and distortion are lowered too. You should notice that I used the lowest extension and low-Q settings in my tests, which make the compression and THD graphs look somewhat worse when compared to subwoofers with lesser extension. So always remember to check the real output and extension from the frequency response and maximum output graphs when making any comparisons.

If one wants to match the clean (no overloading noises) output in 20 - 30 Hz range with the Monolith, one needs two of the 12" kits or one of the 15" kits (estimate since I haven't measured the 15" kit). The 15" kit should be around 3 - 5 dB louder than a single 12" kit. I would recommend using a 4 cu ft box with the 15" kit for higher deep bass sensitivity. I would recommend this as a minimum configuration for a home theater use, especially if you want to use higher than medium listening levels.

[russ.will]

Thankyou. That is exactly the sort of info I was looking for.

I find your comment regarding the "dry" bass quality of particular note. I like deep extension without necassarily overblowing LF boost. In other words, my house curve isn't exactly as savage as some others I've met and probably goes someway to explaining why the stereo crowd like the Rythmiks.

Given you comments on audible limits, I'll ignore the single 12" designs. The Monolith is delivering comfortable 105dB+ in the mid to low 20Hz at my listening position 3.5m from the sub. I think I would kill a single 12" servo in fairly short order. My recent experiments with dual subs also showed me that I favour one large sub over two small ones, so I'll probably go the 15" route.

In fact, given that the US $ is so weak at the moment and there isn't a larger otion than 15", I'm almost tempted to consider two 15" anyway. With the SMS-1, I could set up one preset for one sub with music and then other presets for two subs and raising the roof with movies.

Thanks again,

Russell

[Ilkka]

Yes, two 15"s would be also my choice for serious HT use. Hey...I DO have two 15"s!

[steve nn]

Yes, two 15"s would be also my choice for serious HT use. Hey...I DO have two 15"s!

That you do

[soho54]

Hey...I DO have two 15"s!

It's getting more common all the time.

[russ.will]

I'm feeling left out

Russell

[paulspencer]

Very happy to see tests for this kit as I own two. I'd also like to see it tested with extension set to 20 Hz low damping. This would give a more fair comparison to the other subs in low end distortion. For HT use, this would be more appropriate as it's ability to handle LFE with authority is compromised using those settings. Brian indicated that the intention behind 14 Hz extension is for music reproduction.

The results fit with my experience - very accurate mid to upper bass making it very suitable for music. IMO, this is what is most difficult for a sub to do. For home theater it seems to require a bit more SPL to sound loud. Low distortion in the midbass would seem more important to me than down low.

[Ilkka]

paulspencer wrote:

Very happy to see tests for this kit as I own two. I'd also like to see it tested with extension set to 20 Hz low damping. This would give a more fair comparison to the other subs in low end distortion. For HT use, this would be more appropriate as it's ability to handle LFE with authority is compromised using those settings. Brian indicated that the intention behind 14 Hz extension is for music reproduction.

The results fit with my experience - very accurate mid to upper bass making it very suitable for music. IMO, this is what is most difficult for a sub to do. For home theater it seems to require a bit more SPL to sound loud. Low distortion in the midbass would seem more important to me than down low.

Unfortunately I don't have that unit in my possession anymore, but I'll see what I can do. I did measure the frequency response using every possible setting (will post them soon) but not distortion.

20 Hz/low damping doesn't yet change the frequency response much. Only around 1 dB down at 20 Hz and 2 dB down at 10 Hz. I would recommend 28 Hz/low or 28 Hz/mid for a larger difference.