Official Rythmik Audio Subwoofer thread - Page 548 - AVS Forum | Home Theater Discussions And Reviews

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Old 08-03-2014, 05:22 AM
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Originally Posted by qguy View Post
MiniDsp vs Rythmik built in HPF

I am currently running a 2 channel system, right now, I am using the built in HPF filter on the Rythmik's plate amp (80hz, slope ?). Assuming that I would also choose the same 80hz cutoff, I am wondering if the Minidsp would sound better than the Rythmiks HPF, basically the main comparison would be the quality of the OP amps employed in both crossovers, if its better, is it worth the $200 (shipping, taxes etc, I am in Asia ) it would cost me to get it ?

Thanks
There is a Marchand passive cross-over on eBay right now, model XM46SB for $130. It is a high-pass only filter, set at 80hz-24dB/octave. If you use 80Hz/24dB low-pass settings on your Rythmik sub, you'll have a symmetrical cross-over using the two together. I would have bought it, but it has RCA jacks, and I need XLR's. Whether or not it has the same 2134 op-amps as the Rythmik x/o I don't know, but Marchand is known for the excellent sound quality of their cross-overs. Worth taking a look at.

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Old 08-03-2014, 09:04 AM
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Their XM series uses BB (TI now) OPA2134's IIRC. However, the XM46 series is a passive (LC) design: http://www.marchandelec.com/xm46.html

Decades before being introduced to the wonderful world of "passive bi-amping" as implemented by AVRs, that is what I had in mind for passive bi-amping.

HTH - Don

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Old 08-03-2014, 10:23 AM
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Originally Posted by DonH50 View Post
Their XM series uses BB (TI now) OPA2134's IIRC. However, the XM46 series is a passive (LC) design: http://www.marchandelec.com/xm46.html

Decades before being introduced to the wonderful world of "passive bi-amping" as implemented by AVRs, that is what I had in mind for passive bi-amping.

HTH - Don
You consider biamping your speakers with the AVR worthwhile?
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Old 08-03-2014, 11:14 AM
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Originally Posted by rcohen View Post
What crossover frequency did you end up going with? I'd recommend experimenting between 60 and 120hz to see what works best with your speakers and room.
Over the past 2 days I have played around with the crossover. As of today I am using 58hz. I know I am a little low on the selected crossover, but to my ears this setting sounds most satisfying. The Maggies are rated to a low end of 40hz. Maybe the 58hz setting is appropriate after all (being about an octave to 1.5 octave above the low end of their range). Initially, I had the subwoofer at the rooms back wall in the right corner of the room. Despite the low crossover, I was perceiving woofer location. So I moved it to being at the right of the main speakers (in the room's right corner). Maybe because of this change in location I also came to realize how critical the phase control is on the Rythmik. In the new room location I was hearing the beat from the subwoofer a little late compared to the other instruments. I came to realize how critical the phase control is on the Rythmik. I needed to dial it in so that the Rythmik was "in synch" with the rest of the instrumentation. Any other tips from folks would be greatly appreciated.
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Old 08-03-2014, 04:38 PM
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Hi all, does any of you have experience with mating electrostatic speakers and Rhytmik subwoofers?
Do you have some recommendations regarding placement of the subwoofers, subwoofer level and crossover setting (cut off frequency and slope)?
Is it possible to get tight and "controlled" bass that matches the electrostatic midrange and treble?

Chris
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Old 08-03-2014, 05:32 PM
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Originally Posted by Bond 007 View Post
You consider biamping your speakers with the AVR worthwhile?
No. Unless using the AVR to drive a line-level crossover to separate amps. While there are theoretical benefits, and some ardent followers, I consider passive bi-amping as implemented by AVRs a waste of time and money. Whatever benefits come from theory are in the mud in the real world. I am of the same opinion on bi-wiring, natch. I just do not see any practical real-world benefit to either. I have numerous posts elsewhere on AVS explaining my position, and of course there are a plethora of threads where many folk have posted their viewpoints pro and con. This is not the thread for it.

IMO etc. - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 08-03-2014, 05:42 PM
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Originally Posted by dazzdax View Post
Hi all, does any of you have experience with mating electrostatic speakers and Rhytmik subwoofers?
Do you have some recommendations regarding placement of the subwoofers, subwoofer level and crossover setting (cut off frequency and slope)?
Is it possible to get tight and "controlled" bass that matches the electrostatic midrange and treble?

Chris
Not specifically Rythmik and ESLs, but they mate fine with my Magnepans and several other people are using them with ESLs. My previous experience led me to conclude only servo designs, or extremely well-designed conventional subs with a darn good amp driving them, would match the performance of my panels (ESL, ribbon, or planer dynamic, have not owned but have heard them all and had at least one of each flavor in my system for a time in the primordial past). The thing that makes most subs not work well with panels has nothing to do with "speed" (and thank you for not mentioning that!); it has to do with distortion and the ability of the sub to quickly start and stop without overshoot and ringing in response to the driving signal. Servo control is an excellent way to provide low distortion and very good driver (cone) control, much better than the vast majority of non-servo designs.

As for placement and technical details, that would depend upon your panels and your room. As evidenced in my other posts, I am not a fan of letting panel speakers handle very LF material. They (with very few exceptions) are just not designed for it and exhibit high distortion and compressed dynamic range as a result. I much prefer to roll off the LF to the panels and let the sub do its thing. My rule of thumb is to cross over at least 1/2 to 1 octave above the speaker's stated -3 dB frequency, and I prefer a sharp rolloff. The conventional Linkwitz-Reilly crossover matches gain and phase at the crossover point while providing 24 dB/octave up and down. That is what I am using in my system.

FWIWFM, IME, IMO, YMMV, etc. - Don
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Old 08-03-2014, 06:59 PM
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Originally Posted by Cingulate Gyrus View Post
...Initially, I had the subwoofer at the rooms back wall in the right corner of the room. Despite the low crossover, I was perceiving woofer location. So I moved it to being at the right of the main speakers (in the room's right corner). Maybe because of this change in location I also came to realize how critical the phase control is on the Rythmik. In the new room location I was hearing the beat from the subwoofer a little late compared to the other instruments. I came to realize how critical the phase control is on the Rythmik. I needed to dial it in so that the Rythmik was "in synch" with the rest of the instrumentation. Any other tips from folks would be greatly appreciated.
Cingulate,

Look at post 16,132 Official Rythmik Audio Subwoofer thread and the write-up (Dialing-in subwoofer when using AVR_Rythmik PEQ3 amplifiers.doc) that AVS member laulau did for a friend. I use this to setup and dial in the Rythmik F12G sub with the KEF E301 satellites.

If you're really interested in getting the bass right for your room, the last section called measuring and measurements with the link to AVS member Jerry Austin's guide to REW is a worthwhile read.
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Old 08-03-2014, 09:15 PM
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Originally Posted by DonH50 View Post
Their XM series uses BB (TI now) OPA2134's IIRC. However, the XM46 series is a passive (LC) design: http://www.marchandelec.com/xm46.html

Decades before being introduced to the wonderful world of "passive bi-amping" as implemented by AVRs, that is what I had in mind for passive bi-amping.

HTH - Don

Since both the Marchand XM46 and the Rythmik high-pass included in the A370 and H600 amps offer 24dB/octave filtering, you may as well use the x/o in the Rythmik sub. Since you already paid for it, it's free!

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Old 08-03-2014, 09:47 PM
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While I agree with sentiment, please note that I am not the one looking for a crossover, that would be qguy.

Also, the Marchand XM46-series crossovers are passive, there are no opamps in them. Marchand XM44-series (and presumably other) active crossovers use 2134 op-amps.

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Old 08-03-2014, 09:53 PM
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Quote:
Originally Posted by dazzdax View Post
Hi all, does any of you have experience with mating electrostatic speakers and Rhytmik subwoofers?
Do you have some recommendations regarding placement of the subwoofers, subwoofer level and crossover setting (cut off frequency and slope)?
Is it possible to get tight and "controlled" bass that matches the electrostatic midrange and treble?

Chris
Which ESL's do you own, Chris? There are ESL users on this forum who are very happy with sealed Rythmik subs in use with their speakers. There is another way to go with dipole speakers; Brian's collaborator at GR Research, Danny Richie, has a version of his 12" paper-cone Servo-woofer optimized for Open Baffle (OB) use. You use two of the woofers in a frame, facing in opposite directions and in opposing polarity. The sub's output is therefore similar, at certain frequencies, to that of panel speakers, dipole.


There is another speaker designer who is a proponent of OB subs by the name of Linkwitz. You may have heard of him! He designed, and builds and sells speakers with OB subs built in. They are very similar to the GR/Rythmik OB sub, but without Danny and Brian's excellent woofer and the Rythmik Servo circuitry and plate amp. The GR Research sub system is not offered as a finished product, but as a DIY package with two woofers and one Rythmik Servo plate amp (it is listed on the Rythmik DIY product page). Double that if you want stereo subs (a good idea if you're crossing-over above 80Hz or so). You can build the frame (plans for which are on the GR Research site), or have them built for you. There is also a woodworker/cabinet maker who is offering flat-pack (knock down, ready for assembly and finishing) H-frames on the GR Research AudioCircle forum. It makes a perfect stand for all models of Quad ESL's (in fact, there is a company in Europe---Gradient---who offered OB subs specifically for the Quad 63 in the 70's-80's, which were in fact designed to serve as stands for the 63's), which is how I use my W-frame variant of the H with Quad 57's.


In my opinion, the OB Servo-Sub is THE way to go with dipole speakers. Fans of OB subs cite their lack of box resonances as one reason for their very clean (some say lean, until they become accustomed to the OB sound. It is absolutely astonishing with standup bass and the lower registers of pianos) bass quality, but also their lack of room "loading", dissimilar from sealed subs. There is a penalty you pay for the sound quality, however: reduced output as you descend in frequency. Only you can decide if the sound quality an OB provides is worth the reduced output it costs. Or, you can go nuts and use the OB's down to, say, 40Hz, and then sealed subs below. It's only money!

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Old 08-03-2014, 10:00 PM
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Originally Posted by DonH50 View Post
While I agree with sentiment, please note that I am not the one looking for a crossover, that would be qguy.

Also, the Marchand XM46-series crossovers are passive, there are no opamps in them. Marchand XM44-series (and presumably other) active crossovers use 2134 op-amps.
I know that (qguy is the one looking), ya big silly. Say, how does Marchand achieve 24dB/octave passively?!

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Old 08-03-2014, 10:06 PM
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Originally Posted by BDP24 View Post
I know that, ya big silly. Say, how does Marchand achieve 24dB/octave passively?!
Ah, I see.....inductors and capacitors. How that design compares with active opamps would seem a good question.

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Old 08-03-2014, 10:54 PM
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Originally Posted by DonH50 View Post
No. Unless using the AVR to drive a line-level crossover to separate amps. While there are theoretical benefits, and some ardent followers, I consider passive bi-amping as implemented by AVRs a waste of time and money. Whatever benefits come from theory are in the mud in the real world. I am of the same opinion on bi-wiring, natch. I just do not see any practical real-world benefit to either. I have numerous posts elsewhere on AVS explaining my position, and of course there are a plethora of threads where many folk have posted their viewpoints pro and con. This is not the thread for it.

IMO etc. - Don
I agree. I know you know your stuff so I was just wondering what you thought.
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Old 08-03-2014, 11:38 PM
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Originally Posted by DonH50 View Post
Not specifically Rythmik and ESLs, but they mate fine with my Magnepans and several other people are using them with ESLs. My previous experience led me to conclude only servo designs, or extremely well-designed conventional subs with a darn good amp driving them, would match the performance of my panels (ESL, ribbon, or planer dynamic, have not owned but have heard them all and had at least one of each flavor in my system for a time in the primordial past). The thing that makes most subs not work well with panels has nothing to do with "speed" (and thank you for not mentioning that!); it has to do with distortion and the ability of the sub to quickly start and stop without overshoot and ringing in response to the driving signal. Servo control is an excellent way to provide low distortion and very good driver (cone) control, much better than the vast majority of non-servo designs.

As for placement and technical details, that would depend upon your panels and your room. As evidenced in my other posts, I am not a fan of letting panel speakers handle very LF material. They (with very few exceptions) are just not designed for it and exhibit high distortion and compressed dynamic range as a result. I much prefer to roll off the LF to the panels and let the sub do its thing. My rule of thumb is to cross over at least 1/2 to 1 octave above the speaker's stated -3 dB frequency, and I prefer a sharp rolloff. The conventional Linkwitz-Reilly crossover matches gain and phase at the crossover point while providing 24 dB/octave up and down. That is what I am using in my system.

FWIWFM, IME, IMO, YMMV, etc. - Don
Did anyone else spot the contradiction? In the first paragraph: "has nothing to do with speed". Very next sentence: "it has to do with...the ability of the sub to quickly start and stop". Where I come from, quickly refers to speed! Don't fault Don---it's unavoidable.

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Old 08-04-2014, 01:20 AM
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My understanding is I'm supposed to run Audyssey in one-port mode on my FV15HP and then, if I choose, convert the sub to two-port mode, because running Audyssey in two-port mode may lead to boosting of the missing ultra-low frequencies. Is that right? Isn't it a problem because two-port mode produces different sound and Audyssey won't have optimized for that?
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Old 08-04-2014, 03:36 AM
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Any word on when some more F25's will be available? I have two in my room currently but thinking of adding two more.....

Or, what is the consensus on mixing sealed and ported subwoofers? Would adding two FV15HP's be a bad idea? Or maybe just two smaller F15HP's (sealed) to help smooth out response?

Thanks!
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Old 08-04-2014, 04:01 AM
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Thanks for all your response regarding the built in HPF vs Minidsp, I would stick with the built in HPF for now as it currently works and minidsp does not seem to offer me any more additional features that I need for now.
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Old 08-04-2014, 05:08 AM
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Don and BDP, thanks for your replies. I have Soundlab A-1 electrostatic speakers and also 4 Rhytmik F-15's.
I have tried to get the best blending of the two sytems, but until now I haven't succeeded.
The 12dB/octave I like most, not the 24dB/octave. My main speakers have a cut off at about 40Hz with a natural slope of 12dB/octave.
With the F-15's I'm I've set the low pass cut off at 80Hz with 12dB/octave slope. Subwoofer level is very low (4 clicks from zero).

Chris
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Old 08-04-2014, 05:44 AM
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Originally Posted by BigCoolJesus View Post
Any word on when some more F25's will be available? I have two in my room currently but thinking of adding two more.....

Or, what is the consensus on mixing sealed and ported subwoofers? Would adding two FV15HP's be a bad idea? Or maybe just two smaller F15HP's (sealed) to help smooth out response?

Thanks!
We have some F25s coming in two weeks or so.



Enrico Castagnetti @ Rythmik Audio
Media Room: Polk LSiM705s, LSiM706C, LSiM703s | Rythmik F12SE (x2) | Marantz SR7008 | Parasound Halo P5 | Emotiva XPA-3 & XPA-200 | Oppo 105D | Sony HW40ES |
Desktop: Dynaudio BM5 mkIII | Rythmik L22 | Apogee Quartet + Duet | 27" iMac|
Bedroom: B&W 685 S2 | Rythmik LVX12 | Marantz NR1606 | Emotiva XPA-200 Gen 2 | Samsung UN50JU6500 |
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Old 08-04-2014, 06:33 AM
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Originally Posted by laulau View Post
Here's a document that I did for a friend a few years back when he bought a Rythmik. It's an aggregation of info from numerous sources so I don't take any credit (or responsibility) for the information...none of it is etched in stone, so use or disregard any of the info, as you see fit. The document has evolved a lot since I originally did it and is decidedly Audyssey-centric, but if nothing else, it has a bunch of links to helpful references.

YMMV.

HTH
Wow, what a fantastic post. Thank you so much for pointing me to it.
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Old 08-04-2014, 06:38 AM
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Don and BDP, thanks for your replies. I have Soundlab A-1 electrostatic speakers and also 4 Rhytmik F-15's.
I have tried to get the best blending of the two sytems, but until now I haven't succeeded.
The 12dB/octave I like most, not the 24dB/octave. My main speakers have a cut off at about 40Hz with a natural slope of 12dB/octave.
With the F-15's I'm I've set the low pass cut off at 80Hz with 12dB/octave slope. Subwoofer level is very low (4 clicks from zero).

Chris
Ah, the big 'labs... Bearing in mind I last heard Soundlabs ages ago, I found their bass a bit "boomy", probably because it is hard for an amplifier to control such big panels. Back then a Decca ribbon was also a popular addition to help the highs. Anyway, I would play with rolling off the lows to the A1's to see what happens. Blending depends (among other things) upon getting the phase right at the crossover frequency so mains and sub(s) work together (are in phase) at the listening position (LP). Playing a test tone at the crossover frequency and adjust the Rythmik's phase knobs for maximum SPL at the LP is one way to do it. Measuring the impulse response is another, if you've the technical means and knowledge to do so. Away from the crossover, the sound does not instantly fade away, so there will be interaction among sub(s), main speakers, and room. I prefer to minimize interaction between sub and mains by using an active crossover to roll both off with a fairly high slope. If you are not doing that, integration may be more difficult, and placement of subs and mains is more important.

I would try rolling off the Soundlab's low end at 80 Hz with a high-pass filter (HPF) if you can, and moving the subs around (start in pairs because it's easier) to see if there is a sweet spot. You might try a lower crossover (e.g. 60 Hz) to reduce interaction at higher frequencies. Without measurements there will be more trial and error, but frankly with measurements it is still a lot of work to determine interactions among room, subs, and panels and how they relate to your ears at the listening position.

You should "feel" the subs more than "hear" them. The old rule of thumb was that if you hear them they are too loud. Actually that depends on the crossover, placement, and distortion in the subs, but still a useful reminder.

I understand your angst; a pair of big full-range ESLs and four subs is a lot of variables to manipulate. - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 08-04-2014, 06:56 AM
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Originally Posted by BDP24 View Post
I know that (qguy is the one looking), ya big silly. Say, how does Marchand achieve 24dB/octave passively?!
24 dB/octave implies fourth-order response, which can be achieved using two inductors (L's) and two capacitors (C's). For a LPF, you could start with a series L, then C to ground, then another L in series, then a final C to ground. For a HPF swap L's and C's. There are other ways but it has been a while since my filter design class. Choice of filter response is another variable (Butterworth, Bessel, Chebyshev, Elliptical, etc.) that affects amplitude response (roll-off, peaking, ripples in passband and/or stopband, and such) and phase response (linear or not, behavior through pass and stop bands, etc.)

Without op-amps a passive filter potentially has lower noise and distortion, assuming you are far away from saturating the inductors (i.e. they are run at low current, typical for line-level filters), but without active buffers the passive design is more sensitive to the source and load impedances since they will impact the filter's response. A common assumption is a low-impedance source and high-impedance load; a good company will specify the assumed source and load impedances beyond which the filter's response is no longer valid. The passive design will also have more loss, though some "active" designs may use unity-gain input and output buffers with a passive filter network inside (one of the buffers could be a gain stage, natch). It is usually easier to adjust the frequency corner of an active design (depending upon the filter topology you can do it with a single control; passive requires you to adjust L's and C's). Most passive designs I have seen are fixed at a single frequency determined by design.

Active or passive will work fine when properly designed and integrated. I have tended to use active as I appreciate the buffers to isolate source and load and you don't have to worry about the inductor's saturating or ringing. Of course, active circuits can ring too... L's tend to get large at audio frequencies, but passive does need a power supply. You can usually adjust an active design's frequency corner (and sometimes other parameters like gain, filter Q/bandwidth, etc.) though some active designs are fixed-frequency. And so forth, many trades.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley

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Old 08-04-2014, 07:33 AM
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Originally Posted by BigCoolJesus View Post
Any word on when some more F25's will be available? I have two in my room currently but thinking of adding two more.....

Or, what is the consensus on mixing sealed and ported subwoofers? Would adding two FV15HP's be a bad idea? Or maybe just two smaller F15HP's (sealed) to help smooth out response?

Thanks!
It's preferable to match, to help insure phase alignment at all frequencies. Be careful to set them all the filter settings the same. It's easy to make a mistake with a lot of subs, especially since the Rythmiks have a lot of adjustments.

Also, make sure you can time align them. I have a receiver with 2 sub outs, so I have the front 2 using sub 1 and the back to using sub 2. Without the time alignment, it's a mess.

I have a big room, but I liked going from two F25s to 4. Not as big as going from 1 to 2, but the seat to seat consistency improved and the extra subsonic headroom is fun.

Last edited by rcohen; 08-04-2014 at 07:36 AM.
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Old 08-04-2014, 07:58 AM
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Originally Posted by rcohen View Post
It's preferable to match, to help insure phase alignment at all frequencies. Be careful to set them all the filter settings the same. It's easy to make a mistake with a lot of subs, especially since the Rythmiks have a lot of adjustments.

Also, make sure you can time align them. I have a receiver with 2 sub outs, so I have the front 2 using sub 1 and the back to using sub 2. Without the time alignment, it's a mess.

I have a big room, but I liked going from two F25s to 4. Not as big as going from 1 to 2, but the seat to seat consistency improved and the extra subsonic headroom is fun.
I just read a helpful post concerning phase alignment determination. "There is a method for setting the phase control that guarantees perfect phase alignment between the subwoofer and main speakers. First, reverse the connections on your main loudspeakers so that the black speaker wire goes to the speaker’s red terminal, and the red speaker wire goes to the speaker’s black terminal. Do this with both speakers. Now, from a test CD that includes pure test tones, select the track whose frequency is the same as the subwoofer’s crossover frequency." My question is can I use this approach for phase alignment (even though I don't have a disk with pure test tones) by putting on a bass heavy track and altering the Rythmik phase alignment dial for when I hear the least bass?
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Old 08-04-2014, 09:33 AM
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Originally Posted by Cingulate Gyrus View Post
I just read a helpful post concerning phase alignment determination. "There is a method for setting the phase control that guarantees perfect phase alignment between the subwoofer and main speakers. First, reverse the connections on your main loudspeakers so that the black speaker wire goes to the speaker’s red terminal, and the red speaker wire goes to the speaker’s black terminal. Do this with both speakers. Now, from a test CD that includes pure test tones, select the track whose frequency is the same as the subwoofer’s crossover frequency." My question is can I use this approach for phase alignment (even though I don't have a disk with pure test tones) by putting on a bass heavy track and altering the Rythmik phase alignment dial for when I hear the least bass?
We're actually talking about two different things.


When matching a sub to mains, you want to match the phase at the crossover frequency. You should tune that for the most bass, not the least. Also, you would need to use a test tone or other technique that will let you look at the level of the crossover frequency at the listening position.


When matching subs with each other, you want to match phase at all frequencies. This can be tricky with different subs, since the phase can shift in a frequency dependent way.


Basically, if sound is coming from two sources, you want the phase to match, not cancel. With a crossover, sound comes from two sources at the crossover frequency. With two subs, sound comes from two sources at all frequencies below the crossover.


If your left, center, and right speakers are different, you may have similar problems.
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Old 08-04-2014, 10:08 AM
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We're actually talking about two different things.


When matching a sub to mains, you want to match the phase at the crossover frequency. You should tune that for the most bass, not the least. Also, you would need to use a test tone or other technique that will let you look at the level of the crossover frequency at the listening position.


When matching subs with each other, you want to match phase at all frequencies. This can be tricky with different subs, since the phase can shift in a frequency dependent way.


Basically, if sound is coming from two sources, you want the phase to match, not cancel. With a crossover, sound comes from two sources at the crossover frequency. With two subs, sound comes from two sources at all frequencies below the crossover.


If your left, center, and right speakers are different, you may have similar problems.
You are right I am interested in making sure the phase alignment between the subwoofer and the mains is dialed in correctly. I have created a CD with 70hz pure test tones. That is the crossover for the subwoofer. Do you agree with the following methodology for making sure the phase alignment is set correctly?

"There is a method for setting the phase control that guarantees perfect phase alignment between the subwoofer and main speakers. First, reverse the connections on your main loudspeakers so that the black speaker wire goes to the speaker’s red terminal, and the red speaker wire goes to the speaker’s black terminal. Do this with both speakers. Now, from a test CD that includes pure test tones, select the track whose frequency is the same as the subwoofer’s crossover frequency. Sit in the listening position and have a friend rotate the subwoofer’s phase control until you hear the least amount of bass. The subwoofer’s phase control is now set perfectly. Return your speaker connections to their previous (correct) positions: red to red, black to black.

Here’s what’s happening when you follow this procedure. By reversing the polarity of the main speakers, you’re putting them out of phase with the subwoofer. When you play a test signal whose frequency is the same as the subwoofer’s crossover point, both the sub and the main speakers will be reproducing that frequency. You’ll hear minimum bass when the waves from the main speakers and subwoofers are maximally out of phase. That is, when the main speaker’s cone is moving in, the subwoofer’s cone is moving out. The two out-of-phase waves cancel each other, producing very little bass. Now, when you return your loudspeakers to their proper connection (putting them back in-phase with the subwoofer), they will be maximally in-phase with the subwoofer. (It's much easier to hear the point of maximum cancellation.) This is the most accurate method of setting a subwoofer’s phase control. Unless you move the subwoofer or main speakers, you need to perform this exercise only once."
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Old 08-04-2014, 12:06 PM
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That will work.

The way I have often suggested is sort of the inverse of that, playing a test tone and adjusting the phase to obtain the maximum reading (preferably on an SPL meter). That does not require swapping speaker leads. Theoretically either way works fine. The argument has been made that it is easier to hear a null than a peak, and that makes sense to me, so go ahead and dial it in per the procedure in your post.

Don't forget to swap the speaker connections back after setting the phase...

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 08-04-2014, 12:41 PM
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Oops...missed the part about reversing the connections. That makes sense.


Alternately, you could download a test tone app from the net or use REW to generate the test tone, and use a free/cheap SPL meter app in a smartphone.


Although a smartphone mic isn't "measurement quality," it's fine at telling you when you've maximized volume at the crossover frequency.
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Old 08-04-2014, 01:51 PM
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Just make sure the smartphone actually reaches down to the crossover with some decent signal level. Some smartphones roll off the mic around the vocal band to reduce noise so there's not much if any signal down at 50 - 100 Hz. The old iPhones rolled of in SW and actually made good measurements (once compensated); the newer ones added parts (HW) so it is a lot harder to get wideband accuracy, even for a relative measurement like this. A cheap $50 SPL meter is not a bad toy to have around.
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"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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