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The pursuit of bass...

Most people would probably say that the most important thing for a speaker to get right is the midrange and I'd have to go along with this myself. If the midrange is too shouty or too recessed or just tonally inaccurate, the other qualities of the speakers are pretty much pointless regardless of how great those qualities might be.

However, with that said, I do not think that the midrange is the most challenging part of a speaker to get right. In my opinion, that award goes to the bass frequencies. Sometimes I listen to a speaker and it is indeed the midrange or treble that is holding back the sound quality, but far more often, for me, it's the low frequencies. I find that I’m more forgiving of midrange flaws. Midrange flaws don’t impact my musical enjoyment as much as bass flaws.

Now, of course, the bass is also the most vulnerable to room acoustics which just exacerbates the problem. But, mostly I blame the speakers themselves. Many fine speaker manufacturers simply ignore the problem by rolling off the bass early. I won't name any specific brands to avoid a flame war, but this is very common. Often I will see specs for frequency response that indicates -6db at 50hz. This is typically very unsatisfying bass. Also, many speakers are not balanced properly across the frequency spectrum so that while they might dig down to 35hz or 40hz, they don't sound like it because the bass is always underwhelming compared to the volume level of the midrange and high frequencies.

The speakers that do attempt to reproduce good solid 40hz bass, often still sound quite bad when reproducing those frequencies. And I'm not talking about pipe organ bass here, I'm talking about the 35hz to 55hz range. Unfortunately, really good minimontors that are amazing with 60hz up, really are missing out on a lot of the presence and atmosphere created by those low frequencies. Emotionally connecting to the music and suspending disbelief is easier with quality bass reproduction. For some reason many audiophiles are willing to live without it. I can understand this since pursing quality bass can be a frustrating endeavor. Also there is cost to consider. Good bass typically comes from bigger speakers and is therefore considerably more costly. But even the best mini-monitors usually commit the sin of omission in the low frequencies.
jaxwired
jax2
3,031 posts
 
Jax2, can you borrow a sub? Perferably one with a phase reversal switch. It can be a small sub that doesn't go very deep. Try it along the wall behind the speakers, with the phase reversed. I'm hoping that its response will "zig" where your main speakers "zag". Also try it along the wall behind the listening position, starting out with normal polarity. Having powered subs in your main speakers is a big advantage here, because in either of these cases you will probably need to adjust their level.

You said that your speakers were "solid", with "no boxes" - could you elaborate?

Thanks for the sub suggestion - Again I have such limited space that it becomes a real estate issue. I have had a sub in here several times before, though not with these speakers as no one would ever listen to these and think they need anything more in the low end. I can reverse phase on my preamp, but of course that would address both sub modules and do nothing like you suggest. I can also separately attenuate the sub sections (as well as the tweeter) on the speakers. I have tried that and the suckout remains unchanged, hovering around -10db while other regions do change. The point I was trying to make is that it's not the specific speakers, but the room that's causing it. Elviukai - there is indeed a peak just below the suckout dip, right at 50hz. Again, a consistent theme no matter what speakers are in place. So it sounds like the only real way to to address this is to alter the position of the system in the room, as Duke suggested from the start?

Duke, the current speakers are AudioMachina Pure System MkII. The body is solid aircraft aluminum (no box - just enough space for the drivers including the sub driver). The online information has not been updated to the Mk. II version, which has changed from Karl's dated website (I'm working with him on an updated site with new images). They are extraordinary speakers...quite unique...sound amazing; basically a full range driver with a subwoofer and supertweeter. If you have not heard them, check them out and introduce yourself to Karl at RMAF. You'd probably enjoy each other. They have attenuators on the sub and on the supertweeter.

The room's been a thorn in my side from the time I had to move my system there from my studio (which I gave up five years ago). I'll include it in this discussion only because it certainly does play a big roll in the pursuit of a full range sound. It is about 11+ feet wide by 24 feet long and the furthest 10 feet of that length opens up to about 16 feet wide with a cathedral ceiling and a 14 foot peak. The system is on the long wall at one end of this space furthest away from where it opens up larger. A big sacrifice I had to make is that the system had to go under the the higher part of the sloped ceiling (ideally I would have it the opposite way). So at the listening position the ceiling is 8 feet, and at the system/speaker it is 11 feet. Speakers are about 30inches off the back wall and listener about 7 feet from the speakers. It's a very challenging room. Hardwood floors with area rugs and lots of hard surfaces which make it very lively. Plants and room treatments are all I have going for me. That and being nearfield does obviate some of the room issues, while making bass a more challenging issue, as I understand it. The overall volume of the space is probably around 2000cf. Any WAF suggestions would be appreciated. Duke, if I do get the chance to borrow a small sub I will try what you suggest, but you're asking me to put it where the bass traps are (directly behind the speakers).
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dbphd
1,616 posts
 
Jax2 asked: What is the difference between pink noise and white noise (noticed the recommendation for white noise in the Geddes reference)?

IIRC, white noise has equal SPL/Hz across the spectrum, whereas pink noise has equal SPL in each octave band. Pink noise is thought to be more relevant to the perception of sound. It's been nearly 50 years since I've had to know such stuff, so my recollection may be faulty, but the distinction is something along those lines. I'd be inclined to use pink noise unless Geddes has a well reasoned rationale for his preference, though white noise generators that meet specs may be easier to find in products aimed at the consumer market.

db
jax2
3,031 posts
 
Many thanks for the 411 on Pink vs White db!!
jax2
3,031 posts
 
Just as a follow-up to my own question, I just received the latest issue of TAS which has a review on a DSP device for subs called the DSPeaker. Based on similar technology being used in subs that have integrated DSP feedback devices, like Velodyne, it is a $350 black box for use with subwoofers without that option. Anyway, the article directly addresses the common problem I'm having of a suckout caused my room modes in the lower regions below 100hz, and then between 100-200hz. The concept of electronic mode correction is suggested as having potential benefit to this problem. The author does report major success with this particular device (not applicable to my particular arrangement as my subs are integral and not standalone), as with the more expensive PARC device. Duke, the author, Robert E. Greene, does mention in passing how effective the potential of your Swarm system might be, towards the end of that article.

On a further note and query, I've just borrowed a better mic to do a bit more in-depth analysis on my laptop (otherwise was relying on the mic in my iPhone and StudioSix software). Can anyone recommend good RTA FFT software for Mac that is freeware or that doesn't cost an arm and a leg?
acoustat6
357 posts
 
Hi Jax, is there a link to the article? Or is this an article you can post a copy of?

Bob
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