Subwoofer: should we even use them at all?

Shameless tangent!

Marty: I'm interested in your experience with room correction. I also use Rythmiks (two 12" very heavy DIY boxes) in a stereo setup. I'm looking into Dirac for room correction (as my only source is a highly optimized computer), plus an active crossover to high-pass the tube amp and send the bass to the subs. Was wondering what your experience was with active crossovers?

Now, more relevant to the original post: I have small floorstanders (B&W 804S), and adding a sub was a good improvement. I started with a REL Storm III as reinforcement to the low end. Using measurement software/mic and a lot of time, I achieved good integration and I was much happier than without the sub. That REL has one 10" driver.
Then I replaced the REL with two 12" Rythmik subs. Much better! Initially they were also used as reinforcement in the lowest bass. I used Earl Geddes approach: both subs running a summed-up-bass signal, both set up with different crossover pounts, different phase, volume, etc (and different adjustments in the PEQ section) to get a smoother room response. And indeed it was a lot better!

Lately I tried an experiment: high-pass the tube amp (and hence the speakers) thru the crossover built into the plate amp of the Rythmiks, that crosses over at 80 Hz. Subs were kept in the same location (for now), but are now used as stereo and with different settings from before. This gave me a better sound. Better soundstage, imaging. I think the explanation is my speakers, while they can reproduce below 80 Hz, do so with higher distortion. Plus the tube amp must not be too happy to go down there either.
So in my experience subs are a very good thing for music. They do take significant effort and time to get right. And the reasons why they are a good thing aren't only about reaching down deep in the bass, but in some cases relieving the amp and speaker from playing where they are not most comfortable doing.

Cheers!

Above 80hz low freq. become touchable. That is why when you use your subwoofer a lot further ( 120-140hz) you become what I call stealth low freq.

That is the main reason why you need an extreme fast subwoofer in response to use easilly to higher freq.

Using till max 80Hz, is like using subwoofer during the 80's!! That was the past, it is about now.

Lewinski,

I've used several active x-overs and I divide them into 2 groups. The analog models included a tubed Marchand, an NHT x-2, and the internal active x-over in my Theta Casablanca. The Marchand was too noisy for me, but that might be unique to that piece, rather than the model, since I've been told that others had more success. The NHT is an excellent piece (and IMHO a great value), but I ended up pairing it with a Velodyne SMS-1. The resulting performance was excellent, but the set-up was a giant PITA (thanks to the Velodyne) and the multi box/cable arrangement was inelegant. The Theta is a really flexible and good sounding unit, too - and a one box solution.

I moved to an Onkyo 5509 pre-pro after I heard Audyssey xt-32. A lot of A/B testing at a couple of local places led to a loan of an Integra pre-pro which I felt was (much, to my taste) superior to the Theta. The crossover in the Onkyo (like most modern pre-pros) is effected in the digital domain. I ended up buying the Onkyo version because I couldn't hear a difference in sound between it and the Integra version, it was significantly cheaper, and I preferred its appearance.

To the x-over question: It's hard to separate the performance of the digital x-over (vs the analog x-overs) because they were integral (pardon the Onkyo Integra pun) parts of two very different pre-amps/pre-pros. In the end, I like the Audyssey powered one-box solution of a pre-pro for my main 2 channel system and that means a digital x-over comes as part of the deal. Whether it's the digital cross, the room correction, the balance of the preamp circuitry, or any combination of the above, the bottom line is that I found it to be a better mousetrap. Since I had already effectively stopped listening to LPs in favor of a server (and consequently didn't really have to deal with the cognitive dissonance presented by ADC and DAC for my analog LPs) I retired my ARC LS-25 and Joule LA-150 without much indecision. As always, YMMV.

Hope that helps. BTW, I've never heard the Dirac correction package, but I've done a bunch of research on it: There's definitely some interesting software there. If you do pull the trigger on Dirac, I'd be grateful if you posted your take on its performance.

I also use the Onkyo PR-SC5509 with Audyssey Pro.

Above 99% of all people use Audyssey as Audyssey say you should use it. There is a big but......Audyssey does not think from the head of how highend is being used. And how big instruments and voices need to be in proportion.

The other limitation is the lost in dynamics. The first 2 times I did it as they tell people to use it. This was in 2010. I was not satisfied enough.

I had thoughts how it could be better. I developed my own way of measuring. These days we measure at totally different places and Heights.

We also measure the subwoofer differently than they do.

They endresuls are way superior to their quality in endresult. I never will share this information with another person. Even not for money. With this I have an extreme advantage over all my competitors. I never had such a big and convincing advantage in audio before.

The differences are: superior dynamics, speed, blacks integration, sharper focus, resolution and atriculation of voices.

The subwoofer is also a lot more dynamic and controlled than you can achieve with the Audyssey way of Pro.

We modified the microphone stand. The Audyssey stand is fully useless. We measure at mm precision.

The new outcomming Onkyo PR-SC5533 in September will not have Audyssey anymore. I will test it for Onkyo when it comes out. For me it will be far inferior in endresult. I still can sell the old one, The new one is good enough for me to sell. The level is not good enough to be used for myself.

In October 2011 Jeff Hedback (Hd Acoustics) and Nyal Mellor (Acoustic Frontiers LLC) published "Acoustical Measurement Standards For Stereo Listening Rooms." Hd Acoustics clients include Ozzy Osbourne, Lifehouse, and Trevor Horn. Page 19: “To obtain the best possible LF response boundary interference issues can be tougher to address. Varying the fixed distances from ‘speaker to boundary’ and ‘listener to boundary’ will reduce strong cancellations. It is a balancing act as one location that may offer a smoother LF response may not provide the optimal midrange and treble response ” (emphasis added) Page 20, paragraph 2: “ everyone desires a ‘flat’ LF response and no modal ringing. Simply, this is a tough achievement. The absurdly large collection of interrelated variables between two fullrange speakers and the room (speaker design, speaker/listener location, room size/construction and acoustical control within) makes this so. It is up to the individual to determine what their limits are as regards placement and acoustical treatments ” (some emphasis original, some added note the qualifying phrase “absurdly large“)

Let us narrow the discussion to bass reproduction systems (subs or full range speakers) properly tuned with appropriate system Q. Audiophiles wrongly describe such systems as having "fast" or "slow" bass, and such descriptions are misleading or worse. Would you want a low E string on a 6-string guitar to be "faster" than the high E? No, of course not. Low E is 82 Hz, high E is 328 Hz. Obviously, the Low E must be "slower"...two octaves "slower" to be exact.

Guess what? Bass is a slower wavelength vs. mid/treble. Of course it must be slower. Double basses are larger than violins by design.

"Slow" bass more accurately describes a bass mode effect unrelated to the speaker itself. Even though modal effects often result in Frequency Response windows of 15 dB or worse, that is not their worst and most audible effect. The worst and most audible effect is that the mode wavelength is completely outside the diatonic scale and unrelated to the original bass note pitch. After the bass note ends on the program, the modal effect continues bouncing between boundaries. Imagine two bass players, one of them plays perfectly, while the other bass is tuned a quarter tone off (sometimes plus, sometimes minus, depending on the mode), and he holds bass notes about a 32nd note too long. This is the inherent effect modes cause, which results in audiophiles wrongly using terms like "slow." Yes, the note didn't end, but the speaker is not reproducing the note, the boundaries make the note. We're talking about the equivalent of over 100% THD. We're talking about bass notes not on the music program.

There are really only two ideal solutions, neither of which require any EQ nor acoustic treatment for small 3 to 6 dB FR windows, and virtually no timing errors as described above. One is a Distributed Sub Array, the other is a Dual Bass Array. The latter might perform even better than the former, but the latter also costs about twice as much and ideally requires subs built into both front and rear walls.

A properly installed Distributed Array has no integration issues up to about 80 Hz because it solves the bass mode before it occurs. All other solutions are band aids attempting to fix the mode after the fact, including EQ, which can't solve the timing error.

Initially, three or four subs seems like 2 or 3 too many. When you hear the performance level, you'll wish you found out about it earlier and never look back. Even 1cf subs can reach -3 dB @ 20 Hz with enough power for HT or music. That's another benefit: ideal bass works just as well for music as it does for HT.