Originally Posted by T&N
After many weeks of research and a few e-mail exchanges with Enrico (who has been very responsive and helpful!) I'm ready to purchase a pair of 12” sealed Rythmik subs (L12s or F12s). I've learned a great deal reading this thread, so rather then pestering Enrico with yet another question (or two, or three....) I'd like to join the conversation here.
Soulburner did a good job. here are my quick comments (it's late).
I'm setting up a dual purpose system. For dedicated two channel listening (my priority) I'll be using a McIntosh MAC-6700 receiver with a pair of PSB Stratus Silvers (-3db at 35Hz), or alternatively a pair of PSB Stratus Minis (-3db at 50Hz). For 5.2 HT I'll be using a newly purchased Denon AVR-4520ci (which I hope will live up to the performance and reliability standards established by it's still going strong, but a bit feature deficient predecessor, my AVR-4800). The MAC-6700 has a HT by-pass mode so it will power the front L&R speakers in all cases.
The set-up for HT seems pretty straight forward: LFE out of the AVR-4520ci to the LFE inputs of each subwoofer. For 2 channel it seems that using the MAC-6700's pre-outs to the subwoofer's Line level inputs is preferred.
If the MAC does not have bass management and adjustable delay you'll need to use the line inputs for the crossover and delay functions. The most critical part of adjusting delay is to match the phase of the mains (L/R speakers) at the crossover point. The phase of the mains is changing and the delay will not in general match the physical distance. It really helps to have measurement capability to get this right, but you can do a decent job by ear simply by playing a tone at the crossover frequency and adjusting the delay for the loudest combined SPL at the listening position. It is affected by room interaction and such so I have not found ears terribly reliable but it's a start.
I'm leaning towards a pair of the L12s because of their smaller form factor and outstanding value (this system set-up / update is part of a fairly extensive remodel project so there's competition for every dollar in the budget), but Enrico suggested seriously considering the F12s because of their enhanced feature set. So I've been looking at the differences and I have some questions:
The F12's have higher performance (better sound), more features, and a hair more output. In addition to the PEQ they have more flexibility in tailoring the damping and extension for optimal sound in your system and room. With as much as you are planning to spend I would not skimp on the sub(s).
- The F12 has a second LFE input. When might this be used? Is there any benefit to using this input instead of the line level inputs for 2 channel listening with the MAC-6700 if I were to incorporate an external crossover and, or external equalization in the future? Or do I achieve the same thing (i.e. an equally clean signal path) by using the line level inputs with the crossover set at the highest frequency and the delay / phase set at 0?
You can sum L+R inputs if you don't have a sub output, and if you use a Y adapter to put them in parallel from a single sub output, you get 6 dB more gain if you need it. I would expect that unlikely in most cases unless your preamp has very low output. If you use an external crossover you can use the LFE input to bypass the internal crossover, eliminating a gain stage in the sub's amplifier.
The LFE input has a hair higher noise floor due to its wider bandwidth. Unless I put my ear right at my sub I can't tell.
- The F12 has speaker level inputs. My prior subwoofer was a Rel, and Rel is very adamant that better performance will be achieved by using the speaker level inputs for 2 channel listening. Is this an option I might also prefer with Rythmik? The Rythmik instructions, and most of what I've read in this thread suggest that the answer is no (unless I'm running very long connections), but I wonder why two respected companies have very different suggestions. Perhaps Rel is using a different type of circuitry on their speaker level inputs?
No idea about REL specifically, but in general speaker level inputs must be heavily attenuated to line level so you are going to have greater noise in the sub's input stages due to that attenuation. Also, since speaker outputs are loaded by speakers, in general the signal from the amp will be noisier and more distorted than that from the preamp outputs. I would have to read why REL says they are better; my experience is the opposite.
- There are several differences oriented towards dialing the subs in (PEQ, enhanced bass extension flexibility, etc.). I think that I understand the benefit of these controls, but in all honesty I'm just not sure how much manual tinkering beyond optimizing the level of control afforded by the L12s I'll want to do, especially with two subs in the system. In addition I may very well end up using an external crossover (so I can high pass filter the main speakers) and some form of external equalization (I may be mistaken, but I believe proper timing requires external intervention that includes delaying the signal to the front L&R speakers, though I'm still unclear on the materiality of this). Any thoughts?
I have run my system with an external crossover until very recently. The speaker has its own crossover and resulting phase, and the sub may not be located at the same point as the main speaker (generally not), so having delay adjustment is critical. If you use an external crossover from the 4520's preamp outputs, Audyssey will handle the phase transition and you can run the crossover's LF output into the F12's LFE input. Otherwise you'll need to adjust the phase.
Main speakers are positioned for optimum imaging and in an HT system must coordinate with the picture. Subs are best placed in the room to counteract room modes and boundary reflections that cause large frequency ripples. Those are almost always different places. With two subs you can place them symmetrically as a stereo pair, or asymmetrically for much enhanced bass response. I ran stereo pairs for ages but have recently gone to mono and placed them to optimize LF response in my room. The difference is significant.
Almost everything (not all) is mixed to mono in the deep bass, and it is non-directional, so I do not miss stereo subs. There are cases where deep bass is actually stereo, and if it is out of phase you will get some cancellation. In practice I have not found that to be a problem, or even noticeable, on the music I have (classical, jazz, country, rock -- a bit of everything). Getting much smoother and deeper bass for the other 99.999999% is very noticeable.
Chances are you'll be like the vast majority and try a few settings but settle on one and never touch it again. I have had mine on 14 Hz and high damping from about day two and never looked back.
- The F12 also offers two different 24db roll off settings, 50Hz (“large” speakers) and 80Hz (“small” speakers). I'm missing something here. Isn't the point that the roll off begins determined by the crossover setting? What am I missing?
I believe the 80/50 Hz selections are fixed, and the other setting uses the adjustable crossover. I have the older amp so am not sure on this.
- Though common to both the L12 and the F12 I'm also wondering if the LPF slope selector is disabled when the LFE input is used?
- Is there anything I've overlooked?
Not sure if you have researched the advantages of the servo; they are significant. It is hard to describe but easy to hear. That is what created a sub that to me competes with the $3k to $5k crowd in sound quality. The PEQ is a nice touch and a feature I have used quite a bit even with room correction. And as already discussed having continuous phase control is critical for proper integration into a system without the ability to phase-(time-)align subs to mains, like a two-channel system without room correction.
I should also note that I'm aware the F12 has a different amp, a different driver, more output, and that it will play lower then the L12. The extra output isn't terribly important to me, but the enhanced low frequency response is a consideration.
In addition to comments on my questions I'd appreciate any other thoughts, or suggestions. As I said earlier I'm leaning towards the smaller form factor and lower cost of the L12s, but I want to be sure that's a thoroughly considered decision. I'd like to avoid wishing I'd gone with the F12s down the road because of performance, or connectivity options. Thanks in advance for any input.
The sonic difference is probably not that great but noticeable to a careful listener, and the feature set is much richer with the F12's. I prefer to buy the best I can get the first time around so have F12's in my system. When I added subs, feature-wise I could have gone with the L12 (and saved some money), but Brian and Enrico were unanimous in feeling I would be better off with more F12's in my system (using Magnepan main speakers, very clean themselves). I spoke with Brian at length via phone and email before my original purchase, and both Brian and Enrico are aware of my tastes through a number of years' association, so I trust them. especially when my gut said the same thing; I saved for a couple of years until my wallet could agree with head and heart.
The one change I would have made was to get the XLR2 amplifiers since I now have fully-balanced preamp and crossover (though as mentioned above I have removed my external crossover). I do not really believe that balanced is audibly superior for the vast majority of home installations, including mine, but I have very long runs to my back subs and they are on a different circuit, so greater noise rejection and obviating ground loops is a Good Thing. Had I to do it over I would have started with the XLR2 amplifiers, but I do not think they were available when I got my first subs. I may swap the amps in my front pair at some point but am not strongly motivated.
HTH - Don