[jsalk]

People often ask why our standard versions of the Rythmic subs are so heavy.

Well, we start with substantial bracing and I thought it would be fun to show you what you normally don't see.



This is the bracing inside our Rythmik 15 cabinet.  The walls add mass as well as they are 1 1/2" thick (1" thick on our Rythmik 12 cabinets).  So when you add the Rythmik driver and amp, you have a rather heavy subwoofer.  All this mass and bracing results in a very inert, non-resonant cabinet that helps create super-clean, super-accurate bass.  It weighs in at 176 pounds.

Of course, if someone should want a lighter subwoofer, we can pare down the design and do that too.


- Jim

[martyo]

Cool Jim. Thanks for the look inside.

[ratso]

looks like something i'd see over at the museum of contemporary art

[Gzerro]

Jim,

Thank you for posting the picture! I have been wondering what it looks like inside.

I can definately attest that it is HEAVY, but the results are well worth it. Extremly tight, dynamic and deep. It measures basically flat in my room to at least 15Hz in full extension mode (using REW and a calibrated mic from spectrum labs). I am not sure if I can hear that low, but I definately can feel it.

Tom

[Big Red Machine]

It needs veneering.

[jsalk]

It needs veneering.

That's planned for version 2.0

- Jim

[Don_S]

Kitty jungle gym.

[Big Red Machine]

Whew!  Then we can know they look as good on the inside as they do outside.  Have to add a peephole and an interior light!

That's planned for version 2.0

- Jim

[JoshK]

I didn't know you were building Rythmic subs!  I don't see anything on the website, is there any threads with details?

[jsalk]

I didn't know you were building Rythmic subs!  I don't see anything on the website, is there any threads with details?

We build all kinds of subs all the time and have been building Rythmik subs for quite a while.  I have not had time to generate any web pages for them.  We basically deal with subwoofers on a custom basis to make sure customers get a sub that meets their needs and budget.  That said, I will work up some pages on them in the near future.

We have done 12" Rythmiks, 15" Rythmiks and 15" Rythmiks with dual passive radiators. 

If you have specific questions about our Rythmik offerings, I'd be happy to answer.

- Jim

[grantc79]

I've ordered a 15 inch Rhythmic not sure if I'm getting the one with the passives or not.

Completely veneered custom out the door it was only 1500 or so and I'll be sure and post pics and a review as soon as I get it.

After reading this thread I am a touch nervous though, I'm 6'5 and workout daily and I'm not 100% sure I can move it.

[Gzerro]

I've ordered a 15 inch Rhythmic not sure if I'm getting the one with the passives or not.

Completely veneered custom out the door it was only 1500 or so and I'll be sure and post pics and a review as soon as I get it.

After reading this thread I am a touch nervous though, I'm 6'5 and workout daily and I'm not 100% sure I can move it.

Congratulations! 

Its actually pretty easy to move around once you negotiate steps, etc. Furniture sliders help alot for experimenting with placement.

[OgOgilby]

Nice work Jim! It's almost a shame to hide it with a cabinet... Hmmm, a plexiglass cabinet would be cool.

-Greg

[floresjc]

Here's the link to my sub. Jim took a pic of it before it shipped, the 15" Rythmik driver is down firing, and the 15" passive radiators occupy opposite sides of the sub. On the back side is the plate amp. Although he doesn't show it, Jim made magnetic grilles that cover the entire face of the sub where the passive radiators are. Very sleek looking. Big boy though.

http://www.audiocircle.com/index.php?topic=72962.0

I can't recommend this sub enough for those who can swing the price tag. It beats the pants off a regular SVS or sealed Rythmik.

[floresjc]

I've ordered a 15 inch Rhythmic not sure if I'm getting the one with the passives or not.

Completely veneered custom out the door it was only 1500 or so and I'll be sure and post pics and a review as soon as I get it.

After reading this thread I am a touch nervous though, I'm 6'5 and workout daily and I'm not 100% sure I can move it.

I wouldn't try moving it yourself, at least I would never do so. The veneer is very smooth and slick, plus the driver on the bottom takes up quite a bit of area, leaving little ledges for your hand. It takes me and one other guy to carry mine around safely, although its definitely a piece I like to set and forget.

[grantc79]

Here's the link to my sub. Jim took a pic of it before it shipped, the 15" Rythmik driver is down firing, and the 15" passive radiators occupy opposite sides of the sub. On the back side is the plate amp. Although he doesn't show it, Jim made magnetic grilles that cover the entire face of the sub where the passive radiators are. Very sleek looking. Big boy though.

http://www.audiocircle.com/index.php?topic=72962.0

I can't recommend this sub enough for those who can swing the price tag. It beats the pants off a regular SVS or sealed Rythmik.

Whats the price difference? How much lower will that thing go vs a normal sealed 15 Rythmik?

[floresjc]

I don't remember exactly what I paid for mine, but I think Jim quoted me $2k or so when I bought it in 2009. It'd be best to ask him what exact pricing would be.

I also don't know the exact specs in terms of how much further down it goes, but it goes deep. The biggest difference that I notice between my sub and my buddy's sealed Rythmik is that I maintain the musicality, but this thing puts out serious SPL if you are running a single sub. I keep the gain cranked way down.

Others who are more into the numbers could probably answer your exact question (or maybe Jim can pipe in since he's built all the different models), but I love the passive radiator design. I'm port noise free since 2009, and I've got a sub that will do movies and music to my liking.

[floresjc]

Here's a comment from Jim to another poster, which I think has some useful info in it for this thread.

Marbles, you drive a hard bargain.  When I see a question like this, I want to take my time so I can provide an appropriate, thoughtful resonse.  Then, a few months later when I finally find the time, I forget I was going to answer.  So I'll take the time now to provide a few quick impressions before my memory fades.

I might point out, here, that we have only done a few Rythmik projects to date.  Naturally, when we build them, customers would like them delivered rather than letting me take them home for an extended period.  So my comments are based on rather limited time with the units we have built.

With that in mind, let me start by saying that I love the Rythmik drivers.  It is natural that I should say this as they are obviously based on the original TC Sounds drivers (as far as I can tell) - drivers I have had a great deal of experience with and that I believe are some of the best deep bass drivers ever. In fact, Thilo may build these for Rythmik - I don't know.  Rythmik simply adds an additional voice coil for use in a feedback loop with their servo amps.

When we built the first 15" Rythmik sub, we tested it against our SongSub.  We set the crossover at about 80Hz and ran music and tones.  The SongSub is a very low distortion sub and the two tracked very similarly to a point.  As the bass went deeper, however, the Rythmik took over.  Of course, it should have since it has more displacement - a 15" driver should move more air than a 12" driver, all else being equal (there is no substitute for displacement).

The nice thing was, this first Rythmik sub was sealed.  So the bass should have rolled off much earlier than the SongSub and it did not.  In this case, the servo forced the system to play deeper than it normally would.  That is the good thing.  The not so good thing is that the amp was almost wide open in order to get the same output as the SongSub with the gain set at about 30% of maximum.  This is because the Rythmik amp is not as powerful in the first place and a good deal of power was consumed forcing the system to play deeper than a sealed system would normally play.  But in the end, there was enough gain to mate well with a pair of stand mounted speakers. (I understand Brian is working on a higher power amp at this time and that will be a nice addition to the line.)

The sound quality was extremely good.  With a little care, it was easy to set the system up to the point where you did not notice the sub was playing.  The only way you could tell is that the system played much deeper than the stand-mounted speakers would have played on their own.  That is the mark of a very good subwoofer - very tight, very accurate and very musical.

How would this system compare to a 15" driver in a cabinet with dual 15" passives and no servo control.  I don't know, but it would be an interesting comparison.  My gut instinct tells me that if the cabinet and passives were designed and tuned correctly, the results would be very similar.  In that case, the servo would not be asked to do as much since the driver would play deep and fairly accurately on its own.  But with the cost of the Rythmik solution, there really isn't any reason to test that hypothesis unless you need more power.  The servo technology is just not that expensive to begin with so why not take advantage of it.

Now, to answer another question, why would we use passives?  Well, to gain better overall performance, you would normally port the cabinet.  This would extend the natural bass response.  The problem is, when you try and play bass around 20Hz or so, port noise becomes a real issue.  You could always increase the port diameter to deal with this, but with these drivers, the port length becomes EXTREMELY long EXTREMELY fast.  It is simply not practical to try and cram an 80" long port into a cabinet that is already rather sizeable.

The solution is passive radiators.  With the help of Jeff Bagby, we determined that two well-tuned 15" passives would provide the performance of a ported cabinet without any port noise at all.  The system would play plenty deep without putting any exsessive demand on the amplifier.  And I think the results worked out very well.  The 15" Rythmik with dual 15" tuned passives required far less gain than the sealed version we originally played with.  I was very pleased with the results even though I didn't have a great deal of time to play with the resulting sub (Josh was waiting for his speakers to ship).

As for my personal sub project, I am just putting the finishing touches on a new subwoofer system for my home theater.  It consists of a pair of HT4 woofer cabinets tuned to 18Hz for in-room repsonse into the mid teens. For those not familiar with the design, these cabinets feature a 12" driver of the same type, combined with a pair of 12" passives.   I will set it up with a Velodyne SMS1 and a pair of 1200 watt amps. I susect the results will be very good - servo or not.  But we'll see...

I wish I had more time to organize my thoughts, but that was off the top of my head with no time for editing.  All to make Marbles happy...

- Jim

[floresjc]

Also, here's a post by Jeff Bagby where he did a rough model when I was spec'ing out the sub with Jim. The whole thread has good info for anyone interested in subs.

After posting, I modeled the driver today myself using my own sofware, which anyone can download, by the way. (Bragging here,  but I find my passive radiator model to be the most complete I have ever found. It will tell you exactly how much mass to add and recalculate all of the parameters with the added mass. It has proved to be very accurate, as Dennis' measurement of the HT4 match my software on the nose - OK, enough bragging  ) Having said that, I came up with almost exactly the same thing you have here. This woofer is a serious BASS driver. I would recommend 4-5 cu ft and would tune it to about 18 Hz as well. Two 15 Radiators will be perfect. My software predicts flat response to 21Hz with no servo, but a only a small boost of 3dB, so with a servo you should be able to get to whatever Brian programs it for. It will also get honkin' loud too, as this combo doesn't push linear Xmax until you are hitting about 114dB and with room gain will likely do this same level at 20Hz (with enought power, that is.) It should be an awesome Subwoofer. I would be glad to offer my assistance in the design process if it is needed in tuning the radiators.


I will also add that the same woofer in 3 cu ft sealed with the Oaudio 500 Watt amp set to the 16 Hz setting will yield response to 16Hz. It just won't play as loud ultimately as the larger PR unit does, but loud enough for most folks I might consider one of those for myself sometime. The bigger box won't fit well in my room.

Jeff B.

http://www.audiocircle.com/index.php?topic=69249.0

[Nuance]

For

Whew!  Then we can know they look as good on the inside as they do outside.  Have to add a peephole and an interior light!

For only only an extra $595!

I've ordered a 15 inch Rhythmic not sure if I'm getting the one with the passives or not.

Completely veneered custom out the door it was only 1500 or so and I'll be sure and post pics and a review as soon as I get it.

After reading this thread I am a touch nervous though, I'm 6'5 and workout daily and I'm not 100% sure I can move it.

HA!   I look forward to the pictures.

So wow - I never realized the insides of the cabinets were that braced.  One of these days I will hire Jim to build me new cabinets for my TC2000 drivers.  When I showed my current cabinets the picture of the Rythmik cabinets Jim built they wept and refused to output bass for the day.