Official Rythmik Audio Subwoofer thread - Page 226

Brian - I used your calculating phase page. Since the phase was vastly different for my right and left speaker, I used the phase of the left and right speakers measured together to calculate the distance for the sub (80 Hz crossover). It appears to be correct I believe?



I experimented with increasing and shortening the distance. The calculated phase plot is the dark green color (13.3 feet). When I increase the distance, the output increases from around 60-65 Hz while decreases from 70-100 Hz. The opposite occurs when I shorten the distance. The output between 60-65 decreases while the 70-100 Hz area increases. It appears the 11.3 and 12.3 feet feet provide a more even response even though the phase is different 11.3 feet = -30 degrees and 12.3 feet = -51 degrees.



It may be impossible to know but do you think the 60-65Hz area is due to my current ported speaker (Ascend 340-SE) or does it have to do with more the asymmetric layout and response of each speaker. I attached the individual response of left, right, and sub. I will have AJinFLA sealed monitors in a week and a half which could test for the lower end integration.

When running REW sweep, should the Limiter be "ON"? Will it affect anything? Does it cause damage to the driver with sweeps starting as low as 10Hz?
Edited by Skylinestar - 7/27/12 at 7:36am

Tom,
I think you defiantly need some form of EQ for any sub. The Audyssey MultiEQ XT does nothing for a sub accept distance and level, no EQ at all. I have not heard the SMS-1 but have read a lot of good things about it; it’s just a little pricey. I went the cheaper more manual route of REW and a Behringer 1124. The manual route I believe is more flexible because you can dial in different curves to find what you like best but it is a lot more work but that’s part of the fun. Paul Spencer wrote three really good articles over on the HIFI Zine on Bass Integration http://www.hifizine.com/issues/bass-integration-guide/ check it out it’s worth the read.
Larry

Does anyone know the thread size for the rythmik sub spike?
Im trying to get some herbies isolation feet and i need the thread size.
Thank you

M10-1.5

Really? Are you sure about that ?

Bill

Larry,

Not a problem as it can get confusing with the different levels of Audyssey. I had the Onkyo 886 with XT and now have the Denon 4311 with XT 32. XT did a very good job EQing my F12SE but XT32 is on a whole different level. If you are curious check out the Audyssey thread in the AVRs forum to get more information on each level of Audyssey.

Bill

I have a Rythmik F12 and I just purchased a denon 4311. I am not sure how the sub settings and Audyssey XT32 work together. Can anyone provide some suggested settings for the sub.

It is on a 7.1 system that is used 70/30 for HT/Music but the accuracy of the music is probably more important to me. Not sure if it matters but the L/R speakers are larger B&W CM9's and do a decent job on their own.

Just use the LFE input into the sub. The settings Brian suggests are in this thread, a search shoiuld turn them up (I don't recall off-hand).

As indicated, use LFE and then just follow the instruction sheet that came with the sub. There is an official Audyssey thread and FAQ with great information, I suggest reading through it first before doing auto-config. Audyssey will undoubtedly configure your B&W as "Large", customize the settings and change them to Small instead. The suggested default crossover is 80Hz. My speakers go down to 30Hz, so I have selected a crossover of 60Hz for fronts in the 4311 configuration. I also prefer to listen to music without Audyssey, for 2 channel listening my setting is to bypass L/R EQ in the 4311, or listen in Direct mode depending on source. This is a personal preference.

While I have the FV15HP accuracy of music was important to me as well, Rythmik does not disappoint.

Good luck!

Found the post from Brian, latest was #6242:

HTH - Don

Don,

Thanks for posting Brian's thought on the settings when using Audyssey . I will recalibrate in the near future and use these settings.

Bill

^^^

Yeah darn, I need to do the same now. I just reconfigured with new speakers over the weekend. It's tough getting a quiet house for two hours!

Thanks! I've been doing a lot of reading here and elsewhere. I know that I'll be experiencing what you experienced in the near future.


I agree. I pulled the trigger on a SMS-1 today and it's already on it's way. From the reading I've been doing its something that I should have done a long time ago.

Thanks for the link. I'll check it out.
Edited by Tom C - 7/26/12 at 7:14pm

Took me five seconds to figure if this post wad replying to my question.
I remember seeing those number at herbies site. Do you also have the herbies isolationfeet?

Thanks

Nope, but I was looking for real pointy spikes when I was going to get a pair of F15's, ones that would fit into the threaded inserts that come on the bottom of them. I've always installed the more-common 1/4-20.
Edited by BDP24 - 7/27/12 at 5:55am

Don---regarding your Maggies.....I've spent the past couple of weeks reading everything on GR's website, and it's sister forum site Audiocircle. Being a technical guy, I'm sure you already know about the challenge of mating dipole main speakers with sealed subs, they having their non-dipole radiation characteristics. Over the years I've read of dipole users unsuccessful attempts at finding a sub they were not dissatisfied with. Well, having now been somewhat educated on the subject by Danny at GR and the DIY community, I am very excited at the prospect of having a pair of dipole subs in the form of two (or three!) GR 16 ohm 12" drivers per side in H-frame Open Baffle cabinets, a Rythmik plate amp on each, to go with my Quads. While waiting for the XLR2 and 3 to go into production, all I need to do is find someone to build me a pair of H-frame boxes. Can anyone recommend a cabinet maker in Southern California with Audiophile sensibilities?!
Edited by BDP24 - 7/27/12 at 6:01am

Anyone can chime in?

^^^ As long as you do not overdrive the sub you can leave the limiter on. I left it on for all my measurements and had no problems. My sweeps went below 10 Hz.

The short answer to your question: no. I don’t live in S CA, so perhaps somebody there can help? You could also check cabinet or furniture makers, or even the local HS, trade-school, or college shop as they often do projects like that.

The long-winded babbling story of me, Maggies, and subs follows…

It was several decades ago when I went through the pain of adding a sub to my Maggies. Finding one that sounded right and wouldn't corrupt the impulse response was a huge PITA. Servos were new then, expensive, and I wasn't sure I bought all the hype. I ended up designing my own, using a driver from an Infinity IRS since it had dual voice coils and working for a dealer I got them at a decent price. Drove one coil, and used the other in the feedback loop of a simple LDI feedback circuit I put on a little PCB with the LPF. All made in the college lab. It blew away quite a few high-priced woofers we had at the store where I worked, and set me on the path of servo subs forevermore. During this same period I discovered I preferred stereo subs although that is very dependent upon the listener, speakers, and room.

In a large room I was able to get pretty good response with minimal treatment. I almost always had some absorption behind dipole speakers (Maggies or 'stats) to kill the back wave and prevent comb effects from driving me nuts (a short drive). My current room is fairly small (13' x 17' x 8.5') and very heavily treated, essentially killing the back wave. That takes away some of the “life” but provides precise imaging and better frequency response. Having done a lot of stage and some studio work, the deadness does not bother me; all the ambiance and imaging is from the recording, not the room.

Because bass wavelengths are so long, dipoles make less sense to me in the bass region; they still become point sources. However, what you are describing certainly sounds like it will be an impressive set-up! For me, I found the main problem was not the dipole radiation pattern, nor even the rising edge that so many associate with “speed”, but rather controlling the sub so it did not “ring” after the transients and muddy up the trailing edge. Servos are one solution; the other I found that works involves expensive amplifiers and careful design.

When I set up my Maggies again a few years ago, I started from that long-ago background experience of wanting servo and stereo. I had sold one of my old servo subs, and the one I had left needed some work and a new amp. After listening to a few subs currently popular, seeing where prices had got to (!!!), and then finding this thread and going through several exchanges with Brian, a pair of F12’s found a home in my system. I could not be happier. Well with the subs, I’d still like a bigger room, and a pair of 20.7’s, but have a couple of boys to get through college first…

HTH - Don

What are the dimensions (height, width, and depth---the thickness of the electronic parts on the backside) of the plate amps?

UPDATE. Never mind, I got 'em.
Edited by BDP24 - 7/28/12 at 6:06pm

I would love to have a pair of big Maggies again myself Don! With my limited knowledge of acoustic theory, I took what I read the Open Baffle guys to be saying is that sealed boxes and OB's load the room in different ways, and that OB's do so in the same way that planars do (as figure 8 dipoles, with nulls to the sides of the panels/cabinets). The sealed sub has a driver that operates into an enclosed box, while the OB driver uses the room as it's box. Open Baffle enthusiasts feel that the OB design results in a leaner, cleaner sound with less boom and bloat, and that OB subs share this quality with the Rythmik Servo-Feedback design, making them unusually compatible. It is claimed that mating a planar speaker with an Open Baffle sub results in the entire range of an instrument, say a piano, being reproduced with the same timbre, texture, and timing from both the planars and the subs. Also, the push/pull operation of the dual drivers in an OB sub lowers the distortion of the system. I don't know if any or all of this is the case, but I will know just as soon as Brian gets in the XLR amps so that I can finish my Rythmik/GR OB subs!

I cannot say how your OB subs will sound; it's been years since I have heard anything like that (and then they were "IB" though infinity is hard to realize in most listening rooms... ) Technology has moved ahead so my prior experience may not apply. In the past, I found them to ring a bit more than sealed subs, leading to them not sounding as good to me (nor measuring as good). However, they were not servo designs. I did not find the radiation pattern made much a difference for the deep bass, where it still acts pretty much like a point source, but I have always used fairly low crossovers with fairly high slopes. A little higher and slope a little less, and matching radiation patterns makes sense.

Let us know how it sounds!

Will do Don. I'm doing the OB's out of optimistic intellectual curiousity (about both the OB's and the GR 12" drivers) as much as anything else, but I'm very excited about them. I'm planning to back them up with a pair of sealed subs (F12's? F12G's? F15's?) ---assuming I sell a drumset and some unused EQ that I have in storage!---for either the sides or back of the room (in opposite phase if in the back, as recommended by Danny Ritchie of GR). I've been away from Hi-Fi for awhile (my last servo-feedback woofers were in my Infinity RS-1b's), and it's fun again!---Eric.
Edited by BDP24 - 8/1/12 at 12:45am

Quick question - does Rhythmik ship to Canada? I cannot find a dealer here, and it looks like only kits can be ordered from the official website for shipping to Canada. I am interested in the F12 or F15.

My HT room as approx. 1500 cu.ft, so not sure if an F12 is adequate. I have some room treatment (two 4'x2'x4" rockwool panels on the front corners and 2 side panels). I was considering the Paradigm Seismic 110 but I figure an F12 may be better bang for the buck with better performance at 20 hz.

Yes, I believe they ship to Canada. Not sure how much shipping is. I'm kinda in the same boat, deciding between a F12 & F15. A Canadian dealer would be awesome though!

Brian, this may have been answered earlier on in the thread but...

What is the ETA for the redesigned FV12 and will it be at the same price point? Thanks.