# Rythmik? Eating my words.



## ejbragg (Dec 13, 2009)

A while back, I started a thread inquiring about the JBL LSR4312SP subwoofer. Although you guys twisted my arm to go with something with a lower frequency spectrum, I remained stand-offish. Besides not believing I needed the extra low frequency extension, I had other reasons, which I kept to myself - mostly, it came down to a bit of laziness, I suppose.

The fact that a [JBL] subwoofer had all the connections I'd need, right out of the box for a pro system, and better still, an automatic system which adjusts the subwoofer settings to the room, using a built-in, self-tuning software, was too much for me to resist. With these two offers alone, I was imagining myself (ok, dreaming of) plopping the unit down, flipping on the switch, and just using it! :heehee:

Up until now, I have not had enough free $ to make the purchase - a good thing, I'm sure. After thinking things over, and looking at the specs of some of the competing subwoofers available, I have had to drop my presuppositions about what I thought I wanted. I have become more skeptical of the JBL system, since after all this time, I still cannot find but one honest review about it (by an unhappy customer), and even that review seems unhelpful.

I have been musing over the threads & test results you guys have posted, and have found myself keenly interested in the Rythmik subwoofers. (So I am ironically looking at one of the most low-ended designs available.) I was actually quite impressed by the SVS PB13, tuned at 10 Hz, but the size will greatly limit my placement possibilities. I believe I may be set on the sealed Rythmik model. Honestly, I mix with the signal around 70 dB or so, since I expose myself for hours at a time - so I am not interested in high output for this project.

I want to first of all, thank you guys (especially Ilkka and your friends in Finland) for all the work posting a library of very useful and helpful information. I do wish I could find a third party who has tested a completed, sealed Rythmik sub, so I can set my mind at ease, knowing it is truly the best choice for me at this point in time. Does anyone know of any such tests?

Thanks.


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## flyng_fool (Apr 10, 2010)

Here you go:

http://www.avsforum.com/avs-vb/showthread.php?t=1342986&highlight=rythmik+review


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## ejbragg (Dec 13, 2009)

Wow. That's a lot of data. The company definitely has an impressive sub. Do you happen to know if there is a similar set of graphs for one of the sealed versions? Thanks.


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## mr.chill (Aug 25, 2011)

Nice, Rythmik subs look really impressive, but I dont like the looks of the ported models  Been thinking about getting a sealed one many times  Would love some testresults like this on the sealed ones.

good output to low 14hz, thats impressive


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## gorb (Sep 5, 2010)

Here's a test of a sealed DIY Rythmik 12"
http://www.hometheatershack.com/for...rythmik-audio-direct-servo-12-sealed-56l.html


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## mr.chill (Aug 25, 2011)

Nice, it actually has some usefull output down to 14hz. Looks like that enclosure is a little bit bigger than Rythmik 12" ones? 12SE looks a little more box like on pics on their website.


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## ejbragg (Dec 13, 2009)

Ahh, yes, I do remember seeing that test. The DIY box, however, may not perform exactly like the company's boxes. The only thing I'm seeing in those tests that I don't like is the compression distortion at the low end that begins to show up around 93 dB. I'd kind of like to see the levels a bit higher before seeing these distortion problems; on the other hand, most of these problems may not be audibly noticeable until > 95 dB.(?) Anyway, I suppose the 15" version would help in that arena. If, in fact, the 15" model will produce 100 dB without noticeable distortion, I think I'd be quite happy. Anyone have a vote on this?

Everything else about this sub appears impeccable (on paper, anyway).


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## mr.chill (Aug 25, 2011)

I think you should go for the 15" version if thats an alternative, on my norwegian forum its highly recommended by the ones that have it. Especially the one with reflex ports


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## ejbragg (Dec 13, 2009)

Yes, I suspect that's about where I'm headed. .... if I can make the larger size fit ... (which will probably necessitate I leave out the ported model)


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## mr.chill (Aug 25, 2011)

If its the widht you have problems with the ported model is actually smaller. But its bigger in the height and depth. But to be honest i dont think the ported models look that cool. But the 15HP looks really cool


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## ejbragg (Dec 13, 2009)

Yes, well, I'm trying to get away w/ as small a unit as possible because I really don't know where it's going to end up. I kinda want to stuff it behind my console. It's semi-open underneath but it might do weird things back there. Worst case, it'll have to sit under the baby grand, behind me - it's one of the only open spots I have available. If I wasn't concerned about power, I would go w/ the 12" version. But it's a decent sized room, and I may need some headroom every now and then.


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## mr.chill (Aug 25, 2011)

I see, if you want headroom 2 or more subs is a great way to go, will flatten out the freq response in your room aswell. But again, it will take more space  

What about stackin two on top of each other?  two 12" hehe


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## ejbragg (Dec 13, 2009)

In the control room, it's nice to have a flat response throughout. However, it's certainly not required! The mix position is a fairly tight spot that is really the only place that has to be normalized at all freqs. The room's not for entertainment. On the other hand, down the road, I will keep open the option to upgrade to duals, or whatever - that's for sure. But at the moment, I have NO sub. So this is going to be a real treat for me!


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## mr.chill (Aug 25, 2011)

Aha, i thought you were using this in your hometheater setup, guess i didnt read the thread good enough sorry. Well rythmik is great to have in a control room  A really hifi correct sub, with lack of distortion and noise


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## ejbragg (Dec 13, 2009)

Just measured the space behind the console. Although it's rather open back there, and the back wall is covered in about 6"'of absorbant material, the limiting factor is the bottom of the desk, which is 15-1/2" off the ground. If I ever get around to making adjustments to that console, it will be to further LOWER it; it's a couple inches too high for my comfort zone.

The F12 is even too tall for the space, especially if I buy an isolation platform for the subwoofer. It appears that The ONLY place available in the room is under the piano, with an underside measuring 25-1/4" high. As long as the isolation platform isn't over 6" thick, I should be okay.


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## ejbragg (Dec 13, 2009)

I've revisited the Rythmik site and another sub caught my eye that I had not considered - the D15SE. This is their downfiring sub, apparently another sealed unit with a similar frequency profile and same speaker / amplifier combo as their F15. I've been wondering, since it seems I'm going to be stuck with only one subwoofer, if there is any advantage of the downfiring sub over the side excursion model? Placement will be somewhat out in the room, a few feet from one side wall, under a piano & out in the open. It would almost seem that the projection of the downfiring model would be better distributed in all directions. Does anyone have an opinion on this matter?

The designers recommend a concrete floor. The studio is a suspended concrete slab, covered with wood.


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## ejbragg (Dec 13, 2009)

No takers on this one, eh? I've poked around in some other forums and noticed there's no firm concensus on the matter, other than a lot of people seem to "like" the front firing models better. I'm supposing such must be the safer bet. (Besides, I've no plans to put carpet under the sub, which is apparently recommended for the d.f. design.)


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## tesseract (Aug 9, 2010)

Carpet doesn't really affect low frequencies enough to be a factor.


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## eugovector (Sep 4, 2006)

tesseract said:


> Carpet doesn't really affect low frequencies enough to be a factor.


It may not absorb low frequencies, but it does help with physical decoupling for those with vibrating cabs.


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## tesseract (Aug 9, 2010)

eugovector said:


> It may not absorb low frequencies, but it does help with physical decoupling for those with vibrating cabs.


Agreed, down firing cabs do have a tendency to walk across the floor.


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## FLAudioGuy (Sep 21, 2011)

Set it on a neoprene pad but I would choose a location other than under the piano. Does it have to go on the floor? It can sit on another object if need be.


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## ejbragg (Dec 13, 2009)

As mentioned earlier in the thread, umfortunately, I'm down to the under side of the baby grand as far as space. Once I gave up on placement behind the console (it just plain doesn't fit) I now have no other workable alternatives. But that piano is not that large; and it's very open.


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## FLAudioGuy (Sep 21, 2011)

I would have reservations about setting it soooo close to a resonant panel, namely, the piano soundboard. Just sayin'  Only real way to tell is to move it there and listen/measure. I do wonder if the subwoofer will have any lasting deleterious effect on the piano. They (pianos) can be delicate and expensive to tune/fix.


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## ejbragg (Dec 13, 2009)

A very good point! My hope is that the frequency response of the sound board is above that of the sub. This seems possible, especially in light if the fact that the piano is a 6 footer. But as you suggested, only way to know is to try it out. As for tuning, I have to tune it every 6 months (sometimes less) for the studio purposes anyway, so that's no big deal. And I can't think of any possible way of permanently damaging the piano with audio.


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## FLAudioGuy (Sep 21, 2011)

ejbragg said:


> A very good point! My hope is that the frequency response of the sound board is above that of the sub. This seems possible, especially in light if the fact that the piano is a 6 footer. But as you suggested, only way to know is to try it out. As for tuning, I have to tune it every 6 months (sometimes less) for the studio purposes anyway, so that's no big deal. And I can't think of any possible way of permanently damaging the piano with audio.


Though the passband of the piano soundboard/strings may be out of the range of the sub. However marginally, since they can both play many of the same frequencies, that, to me, is only one consideration. You may not get any string or panel excitation from harmonic coupling, there is still a vibration that is more mechanical in nature. If a painting or mirror vibrates on a wall from the bass energy in a room, it can be the mass of the painting was excited or sympathetic vibrations travelling through the higher mass of the wall. This is the primary concern I would have with the piano. As having been raised around pianos my entire life, I can assure there are many variables that can affect their performance and mechanical durability. I am only saying, in point, that I would proceed with caution. Car analogy: keep in mind all the loose nuts and bolts on your car were undone from vibration. :hsd: Cheers, mate!


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## ejbragg (Dec 13, 2009)

FLAudioGuy said:


> I am only saying, in point, that I would proceed with caution. Car analogy: keep in mind all the loose nuts and bolts on your car were undone from vibration.


This is the reason why I drive a Toyota!

Seriously, I see your point. The piano is a 1968 George Steck. If you're familiar with pianos, you may recall this make being mostly wood parts, except the obvious hinges and pedals / pedal posts, and the string frame. I'm sure the wood is hard an meant to vibrate. I'm not sure if this means it will vibrate more or less than one with more metal in it. And for sure, the upper harmonics created by low-end sources is always there.

On the other hand, I won't be pumping earthquakes through my sub at 110 dB. I spend most of my day listening at about 60 - 65 dB (at the listening position). Time is the true test.


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## FLAudioGuy (Sep 21, 2011)

Good luck my friend and keep us posted on how it turns out. Cheers! :T


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