Subwoofer gurus, can you spare a minute?

The background: I know jack about subwoofers; never owned or used one. That said, I have been doing some research these last couple weeks, so I’m familiar with some of the basic terminology and concepts.

The hardware: TEAC CR-H101 powering a pair of Klipsch RP-160Ms. The little 20W RMS receiver has four speaker outputs and a single RCA sub output.

The environment: The room in question is almost square, small at just under 1500’^3, carpeted and with a fair amount of predominantly soft furniture. The primary listening position is at one end and centered. The RP-160Ms are on stands at about the midway point of the room and close to the walls on the sides.

Locations for a sub are somewhat limited. The only spot available in between the 160Ms would be against the back wall, at roughly twice the distance from the listening position as the speakers. It’s my limited understanding that this would result in some phase issues. The only other locations would be against the side walls, either directly underneath, or just slightly ahead of one of the 160Ms (though probably somewhat sandwiched between the wall and on overstuffed loveseat).

The budget: One kilobuck.

The goal: To find a powered subwoofer that is tight, clean, crisp and capable of extending the low end of classic rock and metal music in a highly accurate and composed reference type fashion. The ratio between audiophile vs. home theater usage is 100% music to 0% HT.

The contenders: I’m not ruling anything out, but thought it might be helpful to at least establish something of a starting point. If I were to throw these four powered subs in the mix, is there any one that you guys feel stands head and shoulders above the rest?

1) Rythmik F12 - $940 shipped
12” woofer, sealed design, 370W RMS,
Optimized for the audiophile and the only one listed here to feature a servo sub. Some reviewers claim it’s very nearly the equal of many other more well known brands costing several times more. At the same time, it has the least powerful amp among the four, although I don’t know if the servo driver might enjoy any sort of advantage in efficiency.

2) HSU ULS-15 Mk2 - $854 shipped
15” woofer, sealed design, 600W RMS,
Optimized for the audiophile. Another one that is touted for being an excellent bargain and significantly outperforming its price point.

3) JL Audio d110 - $1000 shipped
10” woofer, sealed design, 750W RMS,
Most powerful amp, but smallest woofer in this lineup. I sometimes see people question the price point (value), but rarely the performance.

4) ELAC Debut S12EQ - $699 shipped
12” woofer, sealed design, 500W RMS,
Is relatively new, has good reviews and is interesting because of the unique auto EQ function that uses your smartphone as a calibrated mic to quickly optimize the output to best match any speaker placement - an especially attractive feature to me given the very limited number of placement options available in my listening room.

 

hi infidel . your speakers drop rapidly at ~70 Hz so this should be your starting point crossover setting on the sub. this is my basic "sub spiel" for anyone adding a sub to a 2-channel setup if you want seamless integration and a sub that disappears.
-
mandatory subwoofer features-
1) flat response in the useable range (avoids one-note bass)
2) high level inputs (integrates better, just run inexpensive speaker cables from your amp speaker terminals in parallel with the main speaker connections.
3) phase angle adjustment. lets you tune out the peaks and gaps in the response when you place the sub in the best room position away from the speakers.
4) reverse polarity switch.

I use and highly recommend the JL Audio D110. I was able to integrate it really well with Harbeth monitors and KEF LS50 Speakers. It is a very musical sub that makes the upright bass instrument sound like a bass and provides plenty of punch for kick drums and bass beats- and has all of the features listed above. Good luck and let me know if you would like info on the procedure to set it up.

 

Thanks for the input, avanti.

In terms of setup, how concerned would you be with having your sub situated twice as far away from your listening position as your mains (maybe 14' vs 7')? Do you think I'd be better off having the sub stuffed between a wall and a sofa and slightly in front of the mains. I understand that a phase control can't do anything to speed up the arrival of the music from a sub that's situated behind your mains. But if you were able to use the phase control to ensure that the pressure peaks between the mains and sub were synced (even if not at exactly the same point on the musical note), would that likely be too horribly noticeable?

I was also unfamiliar with the reverse polarity switch. I found this now 15 year old explanation from a gentleman named "herman" on the Audiogon forum:

"This is one of the most misunderstood concepts for the audiophile, perpetuated because manufacturers such as Conrad Johnson and many others use the terms incorrectly. It is also very difficult to explain without pictures of the waveforms.

In a stereo system the signal alternates between being positive and negative, ultimately causing the speaker cone to move back and forth creating sound pressure waves. Polarity refers to whether a signal is positive or negative. Inverting polarity means that what was positive is now negative and vice versa. If the speaker cone was moving out at certain point in time it is now moving in. Swamp is correct that reversing the speaker wires will invert (reverse) polarity.

One problem in understanding this is that many describe this as a phase reversal, which is incorrect. Phase refers to time. If something is out of phase then it is occurring at a time different than the original signal.

Take two identical speakers being fed the identical signal. They are moving in and out in lock step. If I reverse the connections to one speaker, while one is moving in the other is moving out. This is an inversion of the polarity to one speaker, but most people will describe this incorrectly as a phase reversal. They will say that the speakers are out of phase when the correct terminology would be that one speaker has had it's polarity reversed. This terminology is so widely accepted that it is probably impossible to correct.

Take the same two identical speakers being fed the same identical signal but one goes through a slight delay network. They are moving out and in but one lags a little behind the other. They are now out of phase. Your sub has an adjustment to vary the amount of this delay.

When attempting to integrate a sub with the main speakers, you want the positive pressure wave from the sub to coincide with the positive pressure wave from the main speakers at the frequencies that they are both reproducing (around the crossover frequency). Since they are different distances from the listening position, moving in and out at the same time is not enough since the pressure waves have to travel different distances to reach you. By delaying one of the waves (using the 0-180) phase control it may be possible to get these waves to overlap. If the amp to the sub inverts polarity and the main amp does not (or vice versa), then using the polarity inversion switch on the sub will put the polarity correct. You can then use the phase control to fine tune it to make up for the difference in distance."

I think I understand most of what he's saying here, but am caught up a little bit on why someone might need a phase control that adjusts up to 180 degrees and a reverse polarity switch. I mean, even taking the original polarity into consideration, the waves can't ever be more than 180 degrees out of sync, can they?

 

I would suggest looking at Rythmik subs. Very well regarded and are available in different price ranges. I have two Rythmik F12SEs and I'm very happy with them. Brian from Rythmik is excellent and is very helpful answering product related questions via email.

Rythmik Audio • Direct Servo subwoofer products

 

Without much understanding of the effect of phase I would recommend the option that is able to do corrections for you.

That said, happy Rythmik owner here with a 15" sealed version using PEQ, and phase, after running many frequency sweeps to dial it in.

Your main problem will be that no one knows where you will be setting the phase angle because every room, speaker, crossover combination will be different.

Distances from the mains will be different.
There is no standard for the phase angle on your mains. They most likely are slightly out of phase from the mids.
Adjusting the crossover point on the sub will change its phase angle.

There is no telling what settings will work best without measuring.

 

Do you like to occasionally listening to songs with loud (100+ db peak) sub bass (30 hz and lower) that literally moves you? If so, you should consider big heavy sub in your list instead of small light sub.

 

Methinks this will be rather unbalanced-you'll have huge sub capacity, versus limited all else. I am certain your Teac, even though it has a sub out, has no highpass provision internally. In other words, no way to cut the low bass out of the main amp and speakers. So if you are running out of bass now, a subwoofer will not help that at all. You'll have MORE bass, but the Teac will still clip and the Klipsch woofers still go nuts at very low frequencies (since their port "unloads" the woofers.
--> I think some of your budget should get moved towards a new receiver
I say "receiver" because unfortunately very few 2-channel units can highpass. The Outlaw RR2160 is probably the cheapest at like $700-800...well, maybe there's an NAD model. Surround receivers always have built-in speaker size settings, not that it makes setting up a sub well so much easier. Some have various room correction schemes, up to Audyssey which is more sophisticated.
It's OK to use a surround receiver for just 2 channels, many people do this.
P.S. Craiglist has been a source of cheap and pretty new receivers for me for various uses.

 

Two more contenders: REL and SVS.

 

Rythmik gets my nod, I recently added Two Rythmik F8's to my Stereo. A Sealed Design that is very Musical and Tight.

With NO discontent for SVS, the F8's easily outperformed a pair of SVS SB-2000's. But, there is a price advantage to the SVS Subs.

 

I'm no subwoofer guru by any stretch, but I just went through a third attempt at getting a subwoofer to work in my room. All of my research led me to SVS for a couple reasons. First were all the pro and user reviews. Second reason was their easy return policy. The return policy was important to me as I have had trouble integrating subs in the past.
All that said, I bought a used Anthony Gallo MPS-150 sub for a trial. After trying several locations and making all of the recommended adjustments, I found the only location I could live with was putting the on an Auralex Subdude sub centered between the speakers. It sounds very good now and I think I can live with it. An SVS sub may be in my future.

 

Huge fan of 2.1 here...

Any of the subs in your list will do what you want if you keep the volume low and work to integrate them you'll be happy.​

That little TEAC is so SEXY and tiny though!!!! I'd love to see a picture of the room in question - post it in the "Show your rooms" thread!

But alas this post is spot on. I think adding a $1000 sub to that (extremely cool) little combo CD player/amp is overkill. I think you'll be super happy with a $500 sub or smaller. Most quality subs are great for music if you find a place to put them and tune the volume accordingly. I'm using small subs in my office and my living room - the Definitive ProSub 100 I have in my living room is fantastic ($37.50 thrift find). Receiver there is a Marantz SR-7500 that I got for $50 on craigslist. It has proper bass management so the 2.1 configuration works incredibly well. I'm not using the "room correction" function or surround modes, running it as simple 2.1 with eyes out for a nice center channel speaker when I troll the thrifts.

 

Thanks to all for the great recommendations thus far and thanks in particular to @head_unit and @PhilBiker for their willingness to provide something of a reality check, if that's indeed what is most needed at this juncture. In light of these posts, I'm almost embarrassed to admit that just last night, as I was nodding off to sleep, the thought was running through my head that, while I'm sure a Rythmik F12 would be great, the E15 is only a couple hundred more and not really that much bigger...

So yeah, maybe I do need some reining in.

Admitting that, let me just add the following and see if it alters your opinions at all. Due to job requirements and travel, it's been a couple decades since I've had any serious stereo equipment set up in the house. In the interim, my audiophile needs have been met largely by a fairly capable portable iPhone/DAC/Amp/IEM setup that accesses lossless copies of my CD library. The only loudspeaker exposure I've had has been courtesy of bluetooth speakers. The TEAC CD receiver was a present this Christmas and, as Phil so eloquently pointed out, it is dead sexy. Based on its relatively meager amp rating, I decided to pair it with the highly sensitive and wonderfully accurate Klipsch 160Ms. Thus far, I have not in any way been disappointed. Together, the two have rekindled my excitement for hearing music played out loud.

I point this out for two reasons. First, on a macro level, it's almost a guarantee that my little system will grow with time. The most limiting element, clearly, is the receiver, which is the portion that was gifted to me. The RP-160Ms were purchased with the knowledge that, in addition to being a nice complement to the current set up, they would also have the flexibility to integrate into a more capable system at some point down the road. Keeping an eye toward the future has been a consideration in this sub purchase, as well.

Secondly, I fear I may have done a poor job of explaining the perceived limitations of the current set up. In graciously offering his advice, head_unit expressed concerns that a strong self powered sub won't serve as a remedy for a small amp that's being pushed too hard and causing clipping on the low end. I don't doubt the wisdom of that one bit. But that isn't really an accurate description of what I've been experiencing and it's my fault for not being more specific up front. Using a sound meter app on my phone, even my more spirited listening sessions with this set up rarely exceed 98 dB (and most are much closer to 90 dB). Based on the SPL calculator I found online, the power of this amp combined with the sensitivity of the speakers should be able to deliver 106 dB to my primary listening position.

So pushing the amp too hard hasn't been my issue thus far. Instead, it was my understanding that these speakers, as good as they are, do start to drop off fairly significantly below 70 Hz regardless of the SPL. I was simply looking for something that might be able to crisply, cleanly and musically extend the lower end beyond 70 Hz, at all listening levels, in seamless combination with the 160Ms, while still having the capacity to be an integral part of a more powerful system in the future. I had planned on running a second set of wires from the receiver's speaker terminals to the sub's high level inputs. Does that explanation make sense or change the calculus at all? Or am I still suffering from some fundamental misunderstanding?

 

My thinking was also that a quality sub will be something that can continue to be used as the rest of the system is updated. As long as you expect that more things will be updated in the future. If you don't think the rest will change then I'd focus on something more in balance with the existing system.

I couldn't handle the sticker shock of purchasing of an entire system in one shot. My oldest piece is now my speakers which have been in my system for about 14 years. And I bought them used. I don't even want to know the value of all of it at retail if it was purchased all at once.

Your thought of the E15 might be overkill. I basically run an E15SE (without the aluminum cone) but down firing. They no longer offer a down firing version. It's in a room about 24' by 15' with 7' ceilings. The volume knob sits just above an idle. From 1 to 11, it's probably about 3.
For comparison, I listen quieter than most. Most of my listening is around 78db averaged. 90db is rocking out for a song or two tops.

I would think the 12 should be plenty unless you are trying to pressurize a big open room.

Edit, you can email and ask them their opinion. I supplied them my room size and intentions and I was on the border of maybe running a 15". I erred on running a big one efficiently.
Also, a funny note. When I asked about front versus down firing their response was to ask about the surface. They didn't recommend the down firing 15" to fire into a wood floor. Mine is on a carpeted concrete slab.

 

Two inexpensive subs will do the job better than one expensive one can.

 

My experience differs. I replaced two BIC F12 subs with one SVS Sealed 12" sub and it not only put out the same amount of SPL, but sounded much better doing it. I now use two of those sealed 12" SVS subs and want for nothing in this small room.

For what it's worth, I don't expect much out of my subs - my mains are 3 dB down at 35 Hz (on paper and in REW) so they are high-passed out of the subs while the subs handle about 42-45 Hz and down.

 

I totally disagree with this statement. So you think two inexpensive subs with questionable build, driver and amp quality will sound better? I've gone the inexpensive sub route in the past and it didn't work out well at all. Started with one Rythmik F12SE and it was far better in all aspects than the cheaper sub it replaced. Hey if you want bloated, boomy and localized bass go the cheap route. I prefer tight, accurate and non-localized bass in my system .

 

Completely makes sense.

For anyone who is wondering here is the specs for the unit that Major Infidel is using:

CR-H101 | TEAC

It is absolutely one of the coolest little audio gadgets I've seen. It's a shame that it's missing proper bass management since it has a sub out, but that may not matter given what you posted above. I'll bet it will keep you happy for years to come.

I strongly recommend looking at smaller subs to compliment what you have. The Definitive Technologies ProSub 100 I have in my living room was a ~$500 model when new (in the late 90s - it's an older model - that's 500 1999 dollars) and I find it to be very musical - it blends with my Polk Audio R50 mains seamlessly to my ears. I don't know if I'd go much lower than that given the excellent capabilities of what you have already. I think a carefully selected $500 class sub properly placed will give you serious smiles.

 

I agree with your points about good vs cheap.

But, even expensive sub can be localized. Case in point, JL Audio d110. Try 90+ db at 30 hz and one can't help but localize it due to excessive body shakes and internal noise. I have tried it in my small 11x11 ft room and also bigger 14.5 x 23 ft room. Same problem.

I am sure your sub is much better in that regard.

 

Concur.

 

Polarity is an electrical property.

Phase is a time property.

In acoustics, both can be measured in degrees.

Polarity is absolute. Two speaker connections are either correctly polarized or they’re not. The connection that isn’t, is considered inverted.

When two loudspeaker drivers producing identical sounds at precisely the same time and those sounds are reaching your ears at exactly the same time, the speakers are said to be in phase. When they’re both producing identical sounds at precisely the same time, but the sound from one speaker is reaching your ears later than the the sound from the other speaker, the speaker that is late is described as out of phase by a certain number of degrees based on the time measurement as plotted on a specific type of graph used for such thing. On an measuring device capable of determining phase accuracy, the difference in phase between two oscillations (e.g., between two speakers aimed at a reference point) is displayed on the device’s screen as an angle, hence the use of degrees for measurement.

Another explanation - the same information as above but put a bit differently - is that phase is a measure of the relative timing between two signals. The phase angle (measured in degrees or radians) is the difference between a measurement point and a reference point in terms of a fraction of a cycle for the frequency being measured. At the specific frequency a single cycle will have a phase angle range of 360 degrees. The phase angle is defined as the position of the maximum peak in the signal relative to the reference point.

Anyway, the use of degrees is appropriate.

 

I totally agree that any sub can be localized. But with better quality subs comes the tools to help correct localization. I'm far from a sub expert but an onboard PEQ, variable phase and crossover settings can be very helpful in correcting localization. Chances are inexpensive subs will not have the tools to try to correct room issues. Again I'm very far from an expert on subs but the more tools there are to fine tune ones sub the better IMO. Even more important is the knowledge on how to use those tools. That is where I'm lacking and depend upon Dirac room correction .

I would say the JL Audio 110 is definitely as good a quality sub as the Rythmik, without a doubt.

 

Granted, my point is not absolute. However the logic as to why two subs are likely better for your set-up is documented and proven. Perhaps you may be limited by space or budget constraints - understandable. But if feasible certainly worth the time to experiment with and conduct measurements of with REW or similar.

 

I think it would come down to which is more of a problem in your system/room: bass nulls and peaks vs. the inferior SQ of the cheaper sub.

No doubt that 2 is better than 1 w/ the same sub.

 

Just make sure the amp is compatible with this idea. Some Class D amplifiers won't work with subwoofers using high level inputs.