Thanks stunta. Do you run the 708Ps full-range, and either way where do you have them crossed?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 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?
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?Oh, that's not my setup. You might want to ask this @Olli.
But I could give you some general advice:
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.
- 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.
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.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 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.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.
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.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'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 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.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.
Thanks stunta. Do you run the 708Ps full-range, and either way where do you have them crossed?
FM8s and TAD CE-1 in a 2.2 setup.
View attachment 96146
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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.