Hi all, I have a 2.1 system with the sub sounding best in the center between the loudspeakers. My speakers have substantial, deep, and detailed bass for their size and with the SS amp I’ve chosen. Thus, the sub’s optimal crossover setting is only at about 28hz. I have plenty of bass amplitude going on -- don’t need "more" bass.
I’m wondering about soundstage effects of having two subs on the outsides of my speakers, though. Having my sub in the center does result in some apparent compression of the low frequencies towards the low-center area. The L and R channels from my preamp are combined at my sub. I know some people may disagree and think that the source of frequencies below 60hz can’t be located by human hearing, but my experience tells me differently.
Does anyone have an opinion on the benefits of 2 subs vs only 1 when there’s no need for more bass oompf?
Hi all, I have a 2.1 system with the sub sounding best in the center between the loudspeakers. My speakers have substantial, deep, and detailed bass for their size and with the SS amp I’ve chosen. Thus, the sub’s optimal crossover setting is only at about 28hz. I have plenty of bass amplitude going on -- don’t need "more" bass.
Rather than more bass it’s about added headroom via more bass capacity for a given SPL (i.e.: less excursion = lower distortion = cleaner, more effortless bass), as well as smoother frequency response from an addition of spread-out bass sources (the latter with a potential proviso, to my ears, certainly with 3 or more sources asymmetrically placed).
You always dial in the sub section for overall balance, irrespective of capacity, but when given more headroom and a smoother FR the perceived bass quality takes a leap ahead. Which is to say: oftentime poorer bass reproduction is sought counter-acted with less gain to "hide" a more obvious character of bass, but at the expense of proper, clean bass balance and fullness. So, in effect a cleaner bass can/should be dialed hotter.
I’ve taken advantage of the design of my pair of tapped horn subs, symmetrically flanking/positioned behind my mains, both with regard to smoother FR and even higher sensitivity in a single move - literally: by more effectively using boundary gain as a means of extending/enlarging the horn by firing into the concrete side walls (instead of straight ahead) at a fitting, calculated/simulated distance. That translates into a sensitivity of 108-110dB’s/1W/1M from 25Hz to >100Hz and a more even FR - win-win.
Many already lower sensitivity and direct radiating subs are only operating in a 1/2 space environment (vs. a 1/8 space ditto mentioned above from a sub principle easily 10dB’s more sensitive in itself), meaning they’ll have to work much harder for a given SPL. This is not without sonic implications, I might add, but few really consider the importance of headroom.
I’m wondering about soundstage effects of having two subs on the outsides of my speakers, though. Having my sub in the center does result in some apparent compression of the low frequencies towards the low-center area. The L and R channels from my preamp are combined at my sub. I know some people may disagree and think that the source of frequencies below 60hz can’t be located by human hearing, but my experience tells me differently.
I absolutely agree with you on this, and this is why I find a pair (and no more, unless placed on top of each other for towers) of symmetrical-to-the-mains placed subs to be paramount. It’s also one of the reasons why I’ve never fully warmed to a DBA sub setup, not least when asymmetrically placed throughout the listening space.
Does anyone have an opinion on the benefits of 2 subs vs only 1 when there’s no need for more bass oompf?
Again, it’s not (as much) about "oompf" than it is a cleaner and smoother bass response with more headroom, but to my mind the addition of radiation area only adds to the realism of sound with better physicality; you can’t really overdo capacity, it’s with you do with it and the advantages it can provide you.
One thing that could lead to being able to locate subs could be that they're causing nearby objects to resonate at higher frequencies and you're hearing that. I'd play around with tone generator a little to see if you can isolate anything.
Long ago in my obsessive phase I made an extremely dead sounding room in my basement. I made dozens of insulation bass traps, got equalizers and measurement mics and found out what accurate was, at least from a frequency response perspective. One thing I realized is that if I clapped near one of my components it made a very audible resonance sound. If something coming out of the speakers set that off it would have been a lot more added distortion than the component put out.
@12manyYes, bass is mixed using L and R just like anything else. But the higher frequencies certainly give much more soundstage positioning cues. Often, the low bass sounds are set evenly between L and R, which is the same as center. Like, for electronic music’s synth bass lines. But recorded upright bass, or a large tympani could be set in the mix more to one side.
I had two SVS subs but was not happy with the quality of the bass for music. I moved to one F12 and I feel the quality is better. However, like the OP, I sense its location in the room and others can too, even though I left one of the SVS subs on the other side (my two svs subs were located R and L of the speakers) and only the F12 is hooked up. If I had only 1 sub it would have to go in the middle but with my set up it can’t. I don’t know how 1 sub in the center would sound having not done that but I think two would sound better at the R and L. I will order another F12 in time.
Question: Does the R and L channels get different bass in songs? Thus is there is right channel low freq signal that differs from the low freq left channel in music from my DAC which outputs as line level right channel and a line level left channel.
Thanks so much for the update. As a fan of Rhythmik subs and an owner of an SB2000 (for home theater only) I especially appreciated your observations comparing the two subs — most enlightening! Glad to hear you found benefits in using two subs, and I’d love to hear your thoughts once you get the second Rhythmic set up and dialed in. I have no doubt it’s gonna be great and color me a little jealous, and there will be a pair of Rhythmik subs in my 2-channel rig as well at some point.
I've got two subs run off miniDSP. I think some kind of DSP is almost essential with subs. I am also running the subs left and right channels. At that point, the subs completely disappear. What I really hate is being able to locate the subs in space.
If I run the subs by themselves, they're really not loud. but if you run the mains without the subs it's very clear that the music is lacking. That, to me, means something is right.
It's worth doing some kind of room eq and dsp to tune in the subs, and while one sub is good two, run left and right channels is what works for us.
Ther seems to be an assumption that bass is omni-directional. It is not. There is a point of origin for the original signal and two subs can resolve that reality. It is like two ears helping locate the direction of a sound or two eyes resolving depth perception. The only instance I can think of that might give false clues as to imaging is if the bass is recorded using a DI [direct in] input to the recording soundboard. In that case, the bass is wherever the recording engineer decides he wants it to be. "Prndlus" seems to be closest to this reality when he discusses soundscape and says, "And we want every directional cue we can get for the best soundscape ". I agree !
Update with a few notes on my short journey here:
(@soix, tagging u since u asked about my findings)
1) Reconfirmed more thoroughly my claim about aural locatability of my Rythmik F12G sub. Anyone can believe me or not, but when it’s only the sub playing music with a very low crossover setting, I can instantly locate where the sound is coming from in the room while facing any direction and standing almost anywhere in the listening room... except when I’m behind the vertical plane made by the sub’s cone. Then it’s a diff story and it’s not locatable. My ears have to be in front of the driver somewhere.
2) I had placed the single sub in the middle of my speakers because I needed the SPL from that single, relatively low output Rythmik, which is focused on speed, not loudness. So that position was necessary (you could say optimal... or not) because I really needed two of these subs to begin with in a room of this size, but only had one. AND, the extra low crossover point sounded the best in that position because of the directional effects I’m hearing with this single Rythmik sub, and how having it pointing right at the listening position affected the sound in the 40+ hz bass range.
3) Having the two subs in play (Rythmik F12G and SVS SB2000) far apart from each other totally alleviated both the directionality/locatability problem, and the issue with needing to use an unusually low crossover point.
4) The Rythmik is a totally different animal. I listened to both of them with speakers off while doing test tones for phase adjustment and with music. There’s actually music and details coming through the Rythmik, both in the lowest frequencies, and up through top of the audible range as it diminishes through the end of the crossover slope. The SVS is just blub, blub, blub, blub, and you really can’t make out musical details anywhere in its output. In comparison, it’s a bunch of noise and sounds really distorted. The Rythmik has so much more purity in its sound. I wasn’t able to get the SVS to blend in with my speakers, blubbing along like that. The Rythmik just disappears.
5) I bought another Rythmik. :)
I completely agree that by seamlessly integrating a sub or two (or four?) the listening experience can be taken to a level that is far more difficult to achieve relying on stereo “mains” alone. With subs added, it won’t be 2-channel anymore, by definition, but it will 110% still sound like it, meaning the sub(s) will not be discernible as a source of sound.
Coincidentally, my goal has always been for the main speakers to be undetectable also. Having 2, 3, 4 boxes in your room, but the illusion that the sound is not originating from them is central to the illusion for me. Speakerless-ness, I call it. If the illusion of speakerless sound is achieved, designations such as 2-channel, 2.1 or 2.2 are, for me, unimportant labels.
Of course the specific qualities of the “speakerless” sound (e.g, tone, dynamics, etc.) one pursues is a matter of personal taste and ever-evolving.
@dean_palmersaid
“That is an opinion that is completely baseless, proven wrong consistently, and only held by insane "2-channel only" types and possibly deaf sheep herders.”
I say….
Thank you making me howl. That is so freakin’ funny!
What sounds good to me is what’s optimal in my system.
For me, the saying is,
What sounded good to me is what was optimal in my system, until I learned about how to improve it.
While I don’t want to be on an endless hamster wheel, this is a hobby for me precisely because I am striving to see if I can make things better.
I have been able to improve the sound in the past, and that motivates me to keep trying -- because it’s fun, not because I have a "grass is greener" dysfunction.
One sub is fine, two are always better. More is better in the case of subs. As others have said, multiples really can better fill out the sound stage and give a really full and balanced experience. One huge fallacy is that subs are for movies and not music. That is an opinion that is completely baseless, proven wrong consistently, and only held by insane "2-channel only" types and possibly deaf sheep herders.
@gladmo Assuming your 7T's have a fairly flat frequency response down past 50Hz fugetaboud stereo.
The only time I didn't need to use the crawl test (you don't actually need to crawl but it won't hurt to do both walk and crawl) to map out my listening rooms bass mode / standing waves was when I used four subwoofers. Once you've mapped the room you'll know exactly, or at least near the optimal subwoofer/s locations.
There's a rub. Your going to need some long interconnects to do the crawl test and most likely a longer pair for the location. You don't need anything exotic. Blue Jeans Cable custom makes economical cables for this purpose.
Since both your subs come with a modicum of equalization you can adjust them individually to your taste then use the one with the remote control as the master to control the volume of both. You'll most likely run them together at a lower volume. They absolutly do not need to match. Good luck with the reward.
Thanks to everyone for their input! I have yet to play with my Rythmik and SVS together, but I'll report back when I do, since at least one person was interested in hearing about it.
I think it's unlikely I'll stick with a single sub forever. Conceptually, two just makes more sense, just based on the info provided in this discussion. 👍🏼
@curtdr, Honestly subs are more for movies or just messing with. They do make a difference with some music but if you mostly listen to music that doesn't have much below 40 hz you don't need them. If you want good bass the most important thing is to live in a lightly built wood frame house that lets a lot of the bass escape through the walls.
I dunno... I might not be popular here in this discussion, but oh well here goes: I went for many years without a sub at all, with my Epi 100s... never felt the need. Have one now, though, and do like it, but it wouldn't be the end of the world if I didn't have one at all.
Maybe it'd be worth the effort if I have time, space, money, and the correct tech and meters and whatnot to balance it all out with two subs, but I'll cross that bridge if I even feel like it when the time comes. Maybe if I have a bigger room or something, or just if curiosity gets the better of me. I'm quite satisfied as is, both with my Epi and my Heresy each w one sub in different rooms.
I do like the one dual-side firing sub that I have with my Heresy IV, positioned right between the speakers... and maybe that two-sided firing helps with the "balance" in my room, but I never localize the sub w my ears... it is a complete disappearing act.
I've just started playing with this in a PC system. I'm buying small subs off ebay for cheap and now have 4. 2 tiny PSB sub series 100s and 2 Episode 8" Evo subs. Episode is a custom install brand and has terrible resale value because nobody knows what they are. I took a small chance for about $150 including shipping and it's definitely better than I'd expect for that price. They're not blow the doors off HT subs but get you down to the high 30s. All 4 subs are sealed.
I've gone from 1 Rel to two Rythmiks and now adding 2 more Rythmiks.
Going from the Rel Storm III (vented) to two Rythmiks F12 (sealed, in heavy DIY box, aluminum cone) was definitely an improvement in every way. My audio setup is in the living room so ergonomics dictate plausible places for the sub/s - which aren't that many. So it's really no surprise that two worked better than one (and 2 servo-driven Rythmiks were cheaper than the Rel to boot).
Later I experimented with stereo vs mono subs (both subs playing the same signal) and didn't hear a "stereo" difference - I was crossing over at 60-70Hz. I used the Rythmik's xo for a while to relieve the main (tube) amp and speakers from reproducing low bass and that was definitely an improvement. I did get a measurement rig to correlate what I heard with what I measured and with what I read in papers/online/books.
Eventually I went with a fully active system and have the signal for the subs sent to a miniDSP 2x4HD and implemented MSO (Multi Sub Optimizer) and believe that was another improvement. With MSO you take measurements of each sub at each listening position you define and the software optimizes (amplitude, delay, PEQ) for the flattest response across the defined listening positions. So I used my two subs to simulate having 2, 3 or 4 subs at the different locations I could live with and ran the optimizations. That showed that 3 subs were better than 2, and 4 were better than 3. This is consistent with Earl Geddes' approach. He has said 3 subs would be enough, provided there is freedom to locate them, which I don't (all need to be on the floor, two visible by the main speakers and two under end tables). So I went ahead and purchased 2 additional F12 kits. I'm building the boxes now.
Still TBD if all this will be worth it, but it has been a fun learning journey 😀
I have 2 subs-10" Eminence. We run these with a Yamaha power amp, commercial. I have never ran out of power. I have a Marchand crossover to make sure the level is right for subs and mains. The crossover is at 100 Hz.I don't have phase adjustment. These subs are where they were for 20 years. I don't know if it would sound better somewhere else. Recently I removed the crossover and ran the speakers fill range. Not as clear, less bass and transients all were not as good. Why? The subs reduce load on main amp and reduce intermodulated distortion. This causes the mids to be not as clear. I have 2 bass traps and 6 first reflection with 3 diffusion panels in rear. I finally have the system so I can walk around the room and the sound is the same, except no imaging. I could buy a couple more bass traps, don't cost much.
@ditusaThe article written by Doug Blackburn exudes confidence and it sounds plausible, but I disagree with a good portion of his assertions due to my experience. "Listen to a subwoofer all by itself for a while. You won’t hear anything vaguely resembling speed coming from that slow, soggy-sounding, plodding subwoofer. It has no detail and no speed whatsoever when heard all by itself."
I’ve done this with different subwoofers and they sound different. The SVS SB2000’s perceived quality of rapidity vs slowness changed significantly when changing its power cable with those of different materials and constructions. I started a discussion thread here about it some time ago.
The way I see it, the audio hobby is really about listening. Some people can detect differences just by listening, so they don’t rely on concepts so much, just like some people who can see clearly at very far distances don’t need corrective lenses. Some people don’t have the ear/brain training/gift/whatever to perceive as acutely, so they rely more on measurementation and abstraction. This is the primary basis for my system building, and the reason I disagree with the author.
I’ll give the other article a read today. I think it’s more up my alley.
The argument that convinced me to go with two subwoofers says:
The bass wave is extremely long at the low end of the sub’s output, and the listener cannot tell where it originates.
The sub’s output higher up the spectrum enters the zone where the listener can tell where it originates.
And we want every directional cue we can get for the best soundscape.
Admittedly not much information is ‘lost’ to the listener with only one sub - if any is ’lost’ at all at those frequencies - you’re already down at 28Hz.
It’s a matter of a few percentage points improvement, maybe only 1% or 2%.
For me it was vital improvement.
Bass and drums took on a richer, finer texture, and the soundscape resolved more completely.
But then, my crossover points are in the low thirties and upwards of fifty for Magnepans.
@james633Sounds like why I chose to give up on the parametric EQ section of the amp on my Rythmik sub, soon after buying it. Sounds significantly better and faster to me without applying a specific FR curve.
Yes group delay matters a lot with subs. group delay and phase are related. The audioholics information is very good.
Many subs are delayed enough they are a full cycle back. The kicker is it can change at different frequencies so you can’t just adjust it out with a simple phase knob. At the lower frequency the cycles are so long (slow) it is less of an issue but still very relevant. It is one of the down side of having all the high tech processing in subs these days. It all takes time even though it is still pretty fast. I personally will not buy a sub unless see the group delay measurement as I feel it is important. In a system where timing can not be corrected (99.9% of 2ch preamps). Think of it as input lag ratings of computer monitors.
Never heard of the term group delay before, but maybe that’s it. The Rythmik sub uses a direct servo motor system to control transient response precision. The SVS in comparison sounds like the cone is slower to change direction. If it’s phase alignment that’s being referred to, I can confidently assert that it’s unrelated to my comments. Both the Rythmik and SVS have manual phase adjustments.
you might be hearing a longer group delay that could make it sound “slow” I have not seen the SB2000 group delay but I was a bit surprised at how high the group delay was on the SB 16 Ultra (link below). It was over 20ms. You could argue at that low a frequency it is less important but still about twice what JL does with their subs. The only way to overcome the delay is using an active system to delay the mains. Receivers can do this and same fancy highnesses as well. Well a mini DSP does to but the output stage is junk. anyway just a guess and thinking out loud.
@james633 I totally believe your anecdote. I also think I have a fortuitously sized and featured listening room for low frequencies. My experience has been far easier than the average report about using single subs that I've read. Nonetheless, I'm getting more and more interested in dual subs as this discussion progresses.
@soixHaven’t tried yet, but the Rythmik F12G is so much faster than the SVS SB2000 that it’s really in a different class. Is a different type of technology altogether.
My plan for when I try putting them into play together is to use a copper power cable on the F12G that I know sounds slower and more smeary and an 11awg 7N OCC silver power cable (which I normally use on the F12G) on the SB2000 to attempt to split the difference in apparent rapidity of response. Not sure if the SB2000 will get anywhere close in speed because of the silver, but my testing in the past showed that it was very responsive to changes in power cables. Much more so than the F12G.
I had one sub broken for awhile (I normally run two) and when I had one I had to really mess around with placement, crossover point etc. got the other sub back so back to two and the System just snapped right back into place. Sounded even and right again. All I can figure is only using one was making lumps in the frequency response and sometimes it sounded fine and other not so much.
now 28hz is pretty low and might not benefit as much. I was running 60hz at the time notes above.
Rhythmik makes awesome subs and I hope the SB2000 (that I also own) can keep up. My guess is it will and that once you get both subs dialed in you’re gonna reap sizable benefits. Keep us posted!
"Cone excursion goes up 4x for every octave lower in frequency. So 40hz needs 4x more excursion than at 80hz. And large cone excursion increases distortion and in particular "intermodulation distortion" (higher frequency (small excursion) signal is modulated by low frequency (large excursion)). The correct way to address this is put a high pass filter (HPF) on front speakers in order to reduce the cone excursion. This issue is particularly bad for ported front speakers as you may notice with full range signal, woofer in ported speakers have far more excursion than that in sealed front speakers. With the cone excursion reduced, the distortion from the front speakers is also reduced and the sound becomes more dynamic and coherent."
@soix I can feel it in my balls that loudspeaker woofer distortion is minimized by passing low frequencies to a subwoofer. That's how I know it's true. Would you like to see the napkin that I've deposited the evidence on?
It’s funny. I had a good sit down with Alon Wolf where I argued that using subwoofers to augment the lowest octaves of bass has advantages over trying to achieve 20Hz and lower bass within one cabinet, not the least of which was room integration and speaker positioning issues. At that time, about 10 years ago now, he was adamant that subwoofers won’t work because they fail on producing an accurate impulse response and he proceeded to sketch me graphs on a napkin to show me why this was so. But now that Magico sells their own subwoofer either Magico has solved that equation or have conceded that the advantages of well-implemented subwoofers outweighs a perfect impulse response. My guess is that Magico customers were asking for subs and Alon is just adding a product to fill this demand, but I’d love to hear his rationalization when he so vehemently argued they couldn’t be implemented accurately. So it goes.
@ditusa Looks like I need to get busy reading to understand my options better. Appreciated! I'm also looking at some FAQs on Rythmik's website about integrating a sub and why they normally advise against using the optional speaker level inputs.
@erik_squiresAh, I see what you mean. I never went that way because I was doubtful of the purity of an active crossover's output and its circuitry. It would be interesting to try though. Does anyone use passive line level high-pass filters for sub integration, and achieve an excellent level of transparency through it?
What sounds good to me is what’s optimal in my system.
This is true but this also assuming you’ve actually tried the alternative: High passing your mains at least at 60 Hz and letting your subs take the heavy lifting.
I don’t know everything you’ve tried, but I’ve never encountered anyone doing what you are now who didn’t end up being very happy to try again with a higher crossover.
@tony1954 Agreed: a distributed bass array is the way to go. But if you can’t get there then two is better than none. Regardless, as others have stated, you need to put in the time & effort to optimize it. For me, it was one of the most cost-effective, biggest bang for the bucks that I’ve spent in this hobby. Huge, comparatively speaking. (Assuming you have a fairly well treated room too. Which is another big bang for the $$.)
I moved from one good REL B1 to three total and then four subs (all set 60 or lower) and when set up properly I do enjoy it more, like most.
If one can 'hear' and localize deep bass I might suggest the overtones or a second order sub crossover getting in the way. I believe something is heard, not the deep stuff though. The four subs I have are not set so loud or set so high as to ever know where they are for me.
The 'air' and additional horsepower are nice additions. Good luck and good idea on trying out the SVS SB-2000 as a test (I have two of those and an SB-3000).
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