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Rythmik FM8

AGLeS

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Has anyone implemented a pair of Rythmik FM8’s as “stands” for bookshelf speakers? If so, please describe your equipment, setup, signal path, and listening impressions. Thanks!
 

stunta

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I have them as stands for JBL 708Ps. Great fit. Currently set up with Dirac DLBC and they integrate well. I used to use them in midbass mode but have recently switched to low HT. Love the flexibility the FM8s provide.
 
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AGLeS

AGLeS

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I have them as stands for JBL 708Ps. Great fit. Currently set up with Dirac DLBC and they integrate well. I used to use them in midbass mode but have recently switched to low HT. Love the flexibility the FM8s provide.
Thanks stunta. Do you run the 708Ps full-range, and either way where do you have them crossed?
 
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AGLeS

AGLeS

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Have a look here. :)

(Previous model, F8.)
Thanks detlev24. Similar questions for you. Did you feed the TADs a full-range source signal, or high-passed through the F8s? Did the Isoacoustic pucks work well?
 

detlev24

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Oh, that's not my setup. You might want to ask this @Olli.

But I could give you some general advice:
  • Choose a crossover frequency between room modes, i.e., where the subwoofer(s) and the main loudspeakers meet the measurement signal's reference SPL [+/- 0 dB] and use filters that sum to a linear frequency response
  • Choose XO as high as possible but not above roughly 100 Hz as otherwise, frequencies get more directional and the subwoofer(s) might become localizable [unless placed next to, or even better, below the main loudspeakers]
  • The FM8 is a special case, as it is intended for use up to 250 Hz: this makes sense with main loudspeakers that have relatively small drivers to reproduce the bass region [which extends up to ~300 Hz]. It might result in improved clarity and minimal ringing, once those small drivers got "relieved" through such a relatively high, high pass filter
  • Linear phase crossover filters seem to result in best time alignment; preferably those with a steep slope.
As for the Isoacoustic pucks, I would expect they do their job but you could also use every other material that is reasonably thick and dampens vibrations; like some types of rubber mats.
 
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nick-v

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In a previous version of my system, I used a pair of Selah Audio Vigore (Scan-Speak Beryllium tweeter, SB Satori midrange, SB 8" woofer) crossed over to a pair of FM8s via a Lyngdorf TDAI-3400. I tried various crossover points and slopes between 60-150 Hz. I was VERY impressed with the FM-8s.

IMG-20190911-170019.jpg
 
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AGLeS

AGLeS

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Oh, that's not my setup. You might want to ask this @Olli.

But I could give you some general advice:
  • Choose a crossover frequency between room modes, i.e., where the subwoofer(s) and the main loudspeakers meet the measurement signal's reference SPL [+/- 0 dB] and use filters that sum to a linear frequency response
  • Choose XO as high as possible but not above roughly 100 Hz as otherwise, frequencies get more directional and the subwoofer(s) might become localizable [unless placed next to, or even better, below the main loudspeakers]
  • The FM8 is a special case, as it is intended for use up to 250 Hz: this makes sense with main loudspeakers that have relatively small drivers to reproduce the bass region [which extends up to ~300 Hz]. It might result in improved clarity and minimal ringing, once those small drivers got "relieved" through such a relatively high, high pass filter
  • Linear phase crossover filters seem to result in best time alignment; preferably those with a steep slope.
As for the Isoacoustic pucks, I would expect they do their job but you could also use every other material that is reasonably thick and dampens vibrations; like some types of rubber mats.
Got it. My intention is to use the FM8s as stands for my KEF LS50s. In that configuration I’m not worried about the FM8’s upper bass being localized. My questions are these: given the FM8’s ability to run above 200hz, is there an obvious sweet spot to cross over that is higher than where the LS50 naturally rolls off, and would this be best achieved running the signal to the amp (and on to the LS50) through the FM8 using its high-pass filter, or via an independent signal to the amp?
 

dwkdnvr

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I just got a pair of FM8s and am using them as stands under my Kef R3s. I only have had limited opportunity to listen due to some family matters, but I also am very impressed with what I've heard so far. I use a MiniDSP SHD and so have extensive xover/eq capability available, but due to time I'm simply running a basic xover at 100Hz and it's working very well. I will do a measurement pass and really dial things in once I have time (hopefully before Xmas), but straight out of the box they're still sounding far better than the 15" Dayton subs I had in the same spot previously.
 

nick-v

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Got it. My intention is to use the FM8s as stands for my KEF LS50s. In that configuration I’m not worried about the FM8’s upper bass being localized. My questions are these: given the FM8’s ability to run above 200hz, is there an obvious sweet spot to cross over that is higher than where the LS50 naturally rolls off, and would this be best achieved running the signal to the amp (and on to the LS50) through the FM8 using its high-pass filter, or via an independent signal to the amp?

The LS50's woofer starts to get unhappy around 200Hz if you look at the distortion measurements @ 90dB.

thd_90db.gif


I would do some experimenting and measuring (if possible) but between 150Hz-200Hz would be a good place to start.

EDIT: You're going to get the best results using a high-pass/low-pass filter because of the nature of the LS50's small woofer (you want to remove the burden of playing bass frequencies from that small woofer). The best value is probably something like a miniDSP SHD where you have a lot of flexibility with the crossover and also Dirac Live correction.
 
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HooStat

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Someone pointed out to me that if you look at the Rythmik or the SVS subs, they also have solid output up to 200 or 300 Hz. What is the benefit of the FM8? I ask because I may get a pair to replace my current sub -- it would fit the available space better because of its narrowness.
 

detlev24

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Got it. My intention is to use the FM8s as stands for my KEF LS50s. In that configuration I’m not worried about the FM8’s upper bass being localized. My questions are these: given the FM8’s ability to run above 200hz, is there an obvious sweet spot to cross over that is higher than where the LS50 naturally rolls off, and would this be best achieved running the signal to the amp (and on to the LS50) through the FM8 using its high-pass filter, or via an independent signal to the amp?
As @nick-v explained, the sweet spot for the LS50 would definitely be above 100 Hz; I would suggest to use "something" [which depends on your room modes] between ~200 Hz and 250 Hz, to keep distortion possibly below 10% @ 90 dB SPL [at 2 meters] - which would allow the system to play loud and clean, when desired.

You have several options to implement such a crossover with proper time-alignment. Some of the more advanced miniDSP devices would do or else, software-only, something like - link updated - Audiolense XO [as @Olli did, if I recall correctly]. Edit: Note, that the FM8 will have to be configured for highest frequency response as per the included Rythmik Audio guides; and all further internal signal processing shall be bypassed (besides volume control).


Someone pointed out to me that if you look at the Rythmik or the SVS subs, they also have solid output up to 200 or 300 Hz. What is the benefit of the FM8? I ask because I may get a pair to replace my current sub -- it would fit the available space better because of its narrowness.
The FM8 rolls-off later, as it is designed for crossovers up to 250 Hz, and therefore most likely shows better transient response above 120 Hz.

It is high(er), thus, makes for a great loudspeaker stand and most importantly for frequencies above 120 Hz: has a front-firing drivers orientation against (dual) side- or (single) down-firing configurations in other subwoofer models.
 
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HooStat

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The FM8 rolls-off later, as it is designed for crossovers up to 250 Hz, and therefore most likely shows better transient response above 120 Hz.
I guess my question is whether it is importantly better, particularly at, say 175-200 Hz. One can get 2 Rythmik L12 or SVS 1000 for the price of one FM8. Again, I ask because the FM8 are more appealing to me, but I am trying to be realistic about the differences in performance.
 

Olli

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FM8s and TAD CE-1 in a 2.2 setup.

Klein.jpeg


1606497493798.png


XO is 165 Hz, ignore the 20 Hz XO.

DAC is a RME ADI2 Pro FS in MCH mode, XLR outs to front FM8s, Benchmark DAC3B connected via SPDIF at 24dBu goes into Benchmark AHB2 in low gain mode.

EQ software is Audiolense XO, streamer is Sonore Microrendu and Roon server is a Mac Mini. Audiolense filters are in Roon's convolution engine.

Usually I have a 2.4 setup with 2 more FM8s in the back, but the cable is broken currently.The broken cable is a TRS to XLR Y splitter that is connected to the PH3/4 outs of the RME and usually drives the FM8s in the back. In this set up the back subs' XO is 63 Hz.
 

detlev24

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I guess my question is whether it is importantly better, particularly at, say 175-200 Hz. One can get 2 Rythmik L12 or SVS 1000 for the price of one FM8. Again, I ask because the FM8 are more appealing to me, but I am trying to be realistic about the differences in performance.
I'm afraid I have no comparable measurements at hand to specificly answer this question. However, I personally would not expect the differences to be huge in terms of a clearly audible improvement that doubtlessly makes the FM8 worth (nearly) double the price. Especially not, since external loudspeakers' time-alignment and room EQ will/should be used. // It would probably be more a question of perfection.

I would suggest you contact Rythmik Audio and ask for more specific information, to be able to decide for youself - without an option to audition the mentioned combinations in advance.(?)
 
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AGLeS

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I guess my question is whether it is importantly better, particularly at, say 175-200 Hz. One can get 2 Rythmik L12 or SVS 1000 for the price of one FM8. Again, I ask because the FM8 are more appealing to me, but I am trying to be realistic about the differences in performance.
Even if there is no discernible performance difference to the L12 (or SVS 1000), to me there is value to being able to use the FM8s as stands for my mains, thereby reducing the overall physical footprint of the system. Whether that’s worth an extra $1,000 is certainly open to debate.
 

stunta

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Thanks stunta. Do you run the 708Ps full-range, and either way where do you have them crossed?

I don't run them full-range. In my prior setup with minidsp DDRC-88A, I had the crossover at 200Hz-50Hz with my REL sub covering 50Hz and below. Now I have the Monoprice processor and Dirac chose 70Hz as crossover, so I've left it at that for now. Dirac thinks more highly of my 708Ps than I originally did. I plan on re-calibrating by setting the FM8s to mid-bass mode; it sounds so good right now that its making me lazy to tweak things. I do think it may help crossing over higher especially for higher SPLs than Dirac measures at. This is what makes the FM8s so special - flexibility.

The other reason I got the FM8s is that I am essentially building a tower speaker with 2 pieces and I don't anticipate replacing the FM8s any time soon. Selling/buying standmounts is a lot easier, logistically.
 

Da cynics

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Are you practicing this esoteric method?

https://www.audiosciencereview.com/...m2-audiolense-digital-crossovers-w-subs.2369/

FM8s and TAD CE-1 in a 2.2 setup.

View attachment 96146

View attachment 96140

XO is 165 Hz, ignore the 20 Hz XO.

DAC is a RME ADI2 Pro FS in MCH mode, XLR outs to front FM8s, Benchmark DAC3B connected via SPDIF at 24dBu goes into Benchmark AHB2 in low gain mode.

EQ software is Audiolense XO, streamer is Sonore Microrendu and Roon server is a Mac Mini. Audiolense filters are in Roon's convolution engine.

Usually I have a 2.4 setup with 2 more FM8s in the back, but the cable is broken currently.The broken cable is a TRS to XLR Y splitter that is connected to the PH3/4 outs of the RME and usually drives the FM8s in the back. In this set up the back subs' XO is 63 Hz.
 
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