Sub Question. One higher quality sub or two lesser quality? (Rythmik vs HSU)

I have narrowed my choices to one Rythmik Audio G22 Dual 12" subwoofer or two HSU Research ULS-15 II. I am trying to keep my budget to under 2K. I like the fact that the Rythmik is servo controlled and seems to be of higher quality. But I also like the thought of two subs vs one.

What say ye, Audiogoners?


If it were me and my money, I would get two HSU’s. You will get more even bass. I run three HSU’s in my 9x13 listening room with very good results. 
for 2 channel stereo listening -- it isn’t about the amount of bass

it is about distribution of the bass and how it matches/mates w your speakers and room

two usually work MUCH better than one if the room is of any meaningful size

suggest you consider older, relatively inexpensive Rels... use high level connections - should be able to get two for just around a grand
Well that's the trick. Finding two of anything used at relatively the same time isn't easy.
Yep,patience  is a virtue.  You have to keep scouring for sale ads. Try hifi shark. I believe you can do a search and get alerts.
Also consider the possibility that "upgraditis" could set in if you go with the 2 lower priced/lower performance subwoofers especially if the higher performance/priced sub was within your financial reach. In that case, it would be wiser to get a single more expensive sub first as it would save you cash in the long run. After you get the 1st sub, skip a burger a day and save the cash for the 2nd one 6 months later. It does require patience.

If you feel that you won't be affected by "upgraditis" too soon, you could go with the dual HSUs. "Upgraditis" is a common disease among audiophiles (reason for this comment).

First, why do you want to add subwoofers.  Second, why wouldn't you go with open baflle subwoofers?  The GR servo subs are around your price range if you're willing to build the frames.
Come on Oz, you know the answer. Right? You have read the DBA threads, right? So you know that with subs more is always better. Right? And they don't have to be the same. And the more you get the less it matters what and where they are. Right?

You may have been looking at my system profile. I no longer have the X3s. I now have Cornwall IV loudspeakers. Even though I know they aren't doing much below the mid 30s, the bass they have is excellent. I am just looking for something to augment that lowest octave.


Check out that pair of Omega Speaker Systems Speed 10 subs here on the gon.  They look pretty interesting.  If you have walnut cornwalls, it might be a good match aesthetically

Yeah I saw that pair a couple days ago. Although it looks interesting, I'm not sure that they could keep up with the output of the cornwalls.
Hello Ozzy,

     You know that I know that you know the answer.  Two subs will perform about twice as well as one sub in virtually any room, including yours.  Two ULS?-15 mk2s would perform very well and, according to their website, they're within your budget:

$739 each with $85 s/h=$824 each/shipped
2 x $824=$1,648

     Here's the link:

Am I missing something?
It's been some time since I owned any HSU subs, so maybe they have gotten better, but I like the build quality and sound of Rythmik and SVS subs a lot more than HSU.  Consider getting two F12s vs. a single Rythmik sub or push your budget a little and get 2 F15HP subs from Rythmik.  I would also take a look at a pair of SVS SB3000 subs.  Right at your budget point and an excellent value.  Or get 4 SB-1000s and make a Swarm!
I own HSU subs and Vandersteen.
The HSU's are very good for the money. The Vandy's, with their crossovers, are, in my opinion, the best- easy integration, and built like tanks, unlike many brands. ( I would do a search here on Audiogon. I remember one brand was using rather inferior parts in their subs).
I bought both of my subs used, as pairs, so check HifiShark like I did.
I will be selling my 2wq's soon, so I can buy the new Sub 3's.

Multiple subs are the way to go, as they reduce room nodes, There is also the DEBRA that Audiokinesis sells. Ralph Karsten (Atmasphere) finds it to be very good, as well.
When I was looking into a second sub, REL themselves told me that getting identical subs was important. Others here have agreed and disagreed with that view. 

Via Audioholics: "Ideally you should use identical subwoofers for the best overall performance, but it is possible to mix and match subwoofer brands and types if you're willing to do the extra work. If using mismatched subs, bear in mind that systems with different low frequency cutoffs may well be in phase and additive over most of their band, but at or below system resonance may well be out of phase. This can put us in the position of having the sub with a higher cut-off frequency reducing overall system output below its cutoff frequency.   This is why we usually recommend using identical subs all around."
I asked Brian at Ryhthmik about the F12 and he didn’t think they have enough output to match the cornwalls in my room.

I’d start with a single sub assuming that the subs used if two are not as good or well matched to the system. Getting the right sub to match is paramount. Best to start with one. That’s all you need if listening from a single sweet spot. Then, if needed to balance out other parts of the room, add more later. I’d stick to a single sub model that matches well though different models might work as long as all match similarly well but I would get one right first then add more of same if needed.

One question I have is how are people connecting multiple subs to their two channel systems not necessarily designed to output to multiple subwoofers out of the box in a manner that maintains proper load?

@mapman asked: 

"One question I have is how are people connecting multiple subs to their two channel systems not necessarily designed to output to multiple subwoofers out of the box in a manner that maintains proper load?"  

I can't speak for others, but the Swarm and DEBRA systems use four passive subs which are normally driven by a single amplifier, and optionally by two amplifiers.   

The amplifier has line-level inputs, and if that won't do, then a voltage divider network can be built to derive a line-level signal from a speaker-level output, with the line-level signal then feeding the subwoofer amp.  

The amp we use is the Dayton Audio SA-1000. 

I would NOT add subs to those Cornwalls, with 15" woofers, ports, and high efficiency horns.

You could easily mess up what you have, it's very hard to add just the lowest ...... down to ....

You are looking at specs that say down to 34hz. that is in a test space, open air, your's are in a room, sound waves contained, reflected, your bass is maintained below 34 I suspect.

I strongly suggest you buy a decent sound meter, see what you are actually getting, and where. Look for any weak/too strong spots, standing or cancelling waves.

With that sound meter, if you add subs, (or change speaker placement) you will be able to measure/adjust the crossover/blend from your listening spot.

2 channel system: 1 pair of subs, directional, located next to the cornwalls, forward facing. Bass is stereo, and the overtones of all low frequencies also give directional cues.

      Yes, I use the Dayton SA-1000, that Duke mentioned, in my AK Debra 4-sub DBA.  It's been on virtually 24/7 in my system for over 5 yrs now and still is performing flawlessly. 
     A good option is to buy one of these for $300-400 from Parts Express or Monoprice and build or buy 4 passive 4 ohm subs and create your own custom swarm. The Dayton also functions as a sort of sub control unit since it has controls for volume, crossover frequency and phase along with l+r ch line level inputs and A+B sets of speaker outputs.  Its 1,000 watt class AB amp has plenty of power to drive four 4 ohm subs and its controls allows for the setting of all four subs together as a group.
   Another method many use is the MiniDSP,  which has a single set of analog L+R line level inputs and up to 4 L+R analog line level outputs to connect up to 4 self-amplified subs.  This unit also has settings for volume, crossover frequency and phase plus the capacity to customize the crossover filter slopes.
    There's many ways to skin a cat.  No matter how you do it, however, the cat can be relied upon to protest vehemently and loudly.

I've never skinned a cat as far as you guys know,
I see two speaker outputs on the Dayton. How does that work to drive 4 subs?

2 on each wired in series?
" I see two speaker outputs on the Dayton.  How does that work to drive 4 subs?

Hello mapman,

     It's actually 2 pairs of speaker outputs on the Dayton sub amp.  I have a front pair of subs connected to the top pair of outputs and the other pair of subs connected to the bottom pair of outputs.
     The connection method of the AK Swarm and Debra systems' subs are also a bit unique as all 4 subs are connected in series/parallel  configuration.

As I read it the two outputs are already in parallel and connecting two subs to each directly would result in 4 in parallel which would could result in loads 2 ohms or less with nominal 8 ohm subs. Two in series to each would seem like a better idea?
Cornwalls are super efficient, so what Brian said makes sense.  I've never felt like they tried to upsell me when I've talked to them.  Did he make a recommendation for your situation?  I'd reach out to the guys at SVS and see what they suggest also.
Mapman wrote:  

"As I read it the two outputs are already in parallel and connecting two subs to each directly would result in 4 in parallel which would could result in loads 2 ohms or less with nominal 8 ohm subs. Two in series to each would seem like a better idea?" 

Sorry I didn't go into detail.  

With one amp and four 4-ohm subs, the connection configuration is series/parallel, resulting in a 4 ohm load.  

With two amps there are several possibilities, but we never ask the amps to drive a load they're not rated for. 


If Rythmik still offers a 10% discount on multiples, you should just be able to get a pair of the E15 subs for $2000. The only difference between the E15 and F15 is the size of the enclosure, and therefore a minute difference in output.

Whether or not the F12 would provide enough output for you is also partially determined by how loud you listen. The F12 standard uses the Rythmik aluminum cone woofer, the F12G the GR Research paper cone woofer. There is no F15G.

If you have large full range speakers that go down to the mid 30s, if you add subs, you need larger ones that deliver output below that range in that there is little to gain to start with otherwise and you don’t want to merely add to the frequencies already there.
Am I missing something here? Please pardon my ignorance but
what about two of the Klipsch  SPL-120?  They've gotten great 
My primary speakers are Tekton DI's which have very respectable bass and good efficiency.  Similar to your Cornwalls in that regard.  I also have a pair of the the Hsu subs you are considering.  I feel they would do a great job of filling in that bottom octave you are after.  Love mine and have no itch to upgrade.
just get 2 of the VTF-3 MK5 HP subs from HSU or try to find 2 of the REL S/5 SHO subs used, if you go with the HSU VTF-3 MK5 HP subs you would be better off using the high level inputs from the amp instead of the LFE input.The high level inputs give a more even lower end sound for 2 channel listening while the LFE connection is more boomy and better suited for HT.
Thanks ozzy62, lovin' this thread.
I am considering building using Rythmik sub module and a pair of 12' in a folded dipole design.
My only response so far was that the measurement device may not be the most accurate compared to an accelerometer .. Then I considered a DSP amplifier module moving away from the Rythmik AB to class D and no servo at all. Chasing the dragon....

I'll be reading with interest. Cheers mate.
I used to have a HSU 3 Mark lV subwoofer and I know there are better but I would buy no other . It's well made and designed , goes very low with very little distortion , has very high wattage amplifier and has all the connections necessary for any need . HSU makes great subs . Rythmik also . Rel is also recommendable .
The issue is never the quality of the sub.  The issue is always how you integrate it.

I would also take a look at a pair of SVS SB3000 subs. Right at your budget point and an excellent value. Or get 4 SB-1000s and make a Swarm!

I agree 100%
Learn your room and speakers and measure your response below 500 Hz before you do anything. Most subs just output distorsion below 25 Hz when playing loud. Professional digital correction of your Cornwalls may give you quite another listening experience.
It’s been said a million times there is no substitute for quality

And always worth repeating. I would rather have 1 higher quality sub than multiple lower quality subs. Add another when finances allow if you think you need to.
Get two powered and connect from amp speaker outputs. Never again will I try to integrate one into a 2 channel music system. 
Thanks for all the replies so far. My inclination at this time is to go with one VTF-15H II with the thought of adding another (or more) if necessary. My room is pretty large and bass friendly. I've never really had an issue with standing waves and actually integrated one Martin Logan sub with some monitors several years ago with no problems. Since the CW IV does very well on it's own, I really need something with high output at lower frequencies. Hopefully I will get lucky and one is all I need.

Still thinking, but this is the way I'm leaning.


Get two subwoofers, one will drive you nuts. If you are using a larger driver in a properly designed sealed enclosure servo is not necessary. The larger the driver the lower the distortion because the larger driver does not have to move as far staying within the linear range of its suspension. This assumes drivers of equal quality. In a two subwoofer system 12" is OK, 15" is ideal as is 4 12" drivers. What you do need is a powerful amp with DSP control. Check this out Then you install one of these and there you have it. Two 15" DSP controlled subwoofers for $2000.00. Spend just a little more and get the 2400 watt amp. These kits go together beautifully. If you are not good at putting on a finish you can cover them in black carpet or take them to a cabinet refinisher who can lacquer them black. Parts Express sells black carpet with an adhesive back.  This is a very serious subwoofer. The driver is first class and significantly better than the ones you mentioned. The amp is no joke either although I would save a little more and go for the 2400 watt version.
The future belongs to the brave so, get out that Gorilla glue and have at it:)
Starting with one to get that right first makes a lot of sense. That’s the engineer in me speaking.

I have a single powered sub setup using a Klipsch SW 308 with a pair of kef ls50s. Connection is line out from Audio Research sp16 preamp to sub using dual phono rca Y connector to merge channels. Simple and Sounds good. The miniDSP approach mentioned above would be interesting to try.

Klipsch sw 308 has one forward facing active driver and dual passive radiators one to each side. That provides 3 different wave launch geometries in the room out of a single sub and allows the sub to be smaller as well. So you get something along the lines of Bass array approach benefits out of a single compact box which works for me in that I like to keep things simple.
Starting with one to get that right first makes a lot of sense. That’s the engineer in me speaking.
I agree with you on that!
... Connection is line out from Audio Research sp16 preamp to sub using dual phono rca Y connector to merge channels.
Aren't your preamp's outputs wired internally  in parallel? If so, doesn't making one output mono make all of its outputs mono?

The Audio Research SP16 has two stereo main outputs. One goes to main amps which remains in stereo and the other to the sub. So that is not an issue.

I’ve learned a lot from Duke (audiokinesis) here over the years in regards to acoustics and sound dispersion in particular and factored that into my choice of a sub with three drivers facing three different directions.

Actually I just checked and one correction.....the Klipsch sub has stereo l/r rca phono plug inputs, so I am actually not using a Y connector there these days with the ARC pre-amp which has the extra stereo main output for it. Glad I checked. I used to have it set up in a different system in another room where I split a single sub output off the integrated amp into dual plugs for both l/r input to this sub using a Y connector..

The Audio Research SP16 has two stereo main outputs. One goes to main amps which remains in stereo and the other to the sub.
I understand that. On many ARC preamps, the main outputs are internally wired in parallel. That would mean you'd get mono out of both outputs even if you only wired one for mono. It looks like the SP16 is an exception.

sp 16 may or may not be exception. As I indicated I am not merging output with a Y connector with the ARC as I mistakenly indicated initially so in fact I have not encountered that scenario.

I suppose one would know for sure pretty quickly if one tried that.