There's a lot more bass in a 6.5" driver than most of you think

Small drivers doing bass or big drivers doing high frequency doesn’t sound like a great plan. There are better ones out there.........

I’ve never said otherwise. My entire point of this thread was about room gain, and how it affects a speaker’s response.

Audiophiles focusing too much on -3 dB points may not fully understand what is affecting their sound quality.

So much misinterpretation. I’ll quote the good Floyd Toole where he explicitly discusses his feelings on the importance of using EQ:

So, if one has a known neutral loudspeaker what does "room EQ" bring to the party? Above about 500 Hz, very little that is reliable - mostly general spectral trends; not detailed irregularities, for reasons mentioned in my last post. At low frequencies equalization is almost certainly beneficial and easily measured steady-state data are all that is necessary.

The full posting is below:

https://www.audiosciencereview.com/forum/index.php?threads/an-enticing-marketing-story-theory-withou...

So, there we have it. Toole explicitly says that EQ is "almost certainly beneficial" for bass frequencies. Stop arguing that he said something else.

I’m done.

@asvjerry

Yep, though all those measurements were quasi-anechoic, while mine are in-room. :)  Plus, those are meant to be near-field monitors. The measurements are overall not atypical for a two way. Shame that built in correction for boundary reinforcement isn't easy/typical in passive and home speakers.

Thanks for the audioxpress article, very interesting about phase and zero phase in recording and playback. It seems like the effects of phase linearity and accuracy are subtle, also.  

You are welcome. One thing I like about Toole a great deal is we hear the same things. Others may find phase and phase linearity big deals, and for them it might be but after lots of listening to Thiel and Vandersteen it is not that big a deal for me. I was thinking of playing with rePhase and Roon to attempt this digitally, but after reading that I'm going to forget about it.

Thanks again for your honest and useful advice.

My pleasure. Glad I helped, I envy your ability to get so much gear installed.  Much more than I can do in an apartment.

Unexpectedly, however, I did notice an improvement in my system’s midrange clarity and the level of detail within the soundstage illusion, too.

@noble100

I literally just read a posting that explains this. Look at the comments from Dr. Kippel:

https://audioxpress.com/article/zero-phase-in-studio-monitors

I quote him below:

For the same reason amplitude modulation (a bass signal f1< 100 Hz modulates a high frequency signal f2> 300 Hz) generates much more differences than phase modulation, aka Doppler).

Of course, it is possible you just had higher order room modes too. :)

I’m currently hesitant to add EQ to my system since my system currently just requires adjusting the cutoff frequency and the volume on my 4-sub DBA bass system’s sub amp/control unit, I don’t believe it’s necessary for bass improvement in my system/room and I believe simplicity is a benefit.

Honestly you’ve done plenty, besides, doing EQ correctly requires a great deal of measurement and fine judgement. I’m not religious about adding EQ when none is required either. In my own space I have a lot of GIK and have lived happily with no EQ until recently adding Roon. The EQ changes I’ve made anyway have been pretty subtle. Now play some Holtz or the sound track to Battlestar Galactica. :)

BTW....I wasn’t aware that Linkwitz had passed away. :( There was a time in my life I lived within a mile of him, and wasn’t aware of it....

Yeah, it was a real shock to me too. The man’s work has been with me since I worked in theater sound in the 1980s. THX used LR filters in the active crossovers they shipped, and I was just getting into filters at the time. Of course, this marriage carried over to the THX satellite/subwoofer standards much later.

I never got to meet him. I read he had retired, and then bam, he was gone.

Best,

Erik

Thanks @asvjerry

To be clear I am not AGAINST the use of multiple subs to solve a problem.

I am against religious advocacy of any particular methodology. EQs, room treatment and multiple subs are all useful choices.

I am reminded of a textbook I read on the National Electric Code, which I will attempt to paraphrase below:

The NEC only tells the electrician what is possible, legal and safe but it is up to the electrician to determine what the right solution is for a given situation.

Best,

E

The one area where EQ is unquestionably needed is in the bass, below about 400-500 Hz - room modes and adjacent boundary effects. It is necessary to attenuate resonant peaks, avoiding filling narrow acoustical interference dips. With multiple subwoofers it is possible to attenuate room modes and for the EQ to benefit more than a single listener. It is not difficult, but not everybody does it. Other mistakes result from trying to "fix" non-minimum-phase ripples in steady-state room curves. EQ at mid and high frequencies should be broadband "tone control" kinds of spectral balance adjustments, but too many systems think they know better.

Well, finally we have enough nuance here to pull apart all the different discussions you’ve been conflating, @pirad. Honestly Pirad, being so well read I have to wonder what your motives are. Did you deliberately misread the Toole article you shared?

This paragraph is pretty much what I’ve been recommending, with the caveat that again, he’s not considering the use of bass traps fully. Bass traps will make those narrow sharp dips less deep, and therefore correctable. He’s talking about the exclusive use of EQ, alone. I have never suggested that as a panacea. I’ve always said that the room acoustics enable the EQ to work. And in fact, his statement here is one you’ve argued against:

The one area where EQ is unquestionably needed is in the bass, below about 400-500 Hz - room modes and adjacent boundary effects.

Yes, this is exactly my point. He’s also recommending a light hand, again, agreed to. Didn’t you try to tell us all EQ was all bad? It’s pretty interesting how you can pull out so many great articles and conveniently omit what doesn’t suit your promotion of swarms. In fact, he never says "if you use multiple subs you don’t need EQ."

Now again, in detail:

With multiple subwoofers it is possible to attenuate room modes and for the EQ to benefit more than a single listener.

Correct. He doesn’t say "you can’t do this with an EQ and bass traps" which is what you keep reading into his words. In fact that’s the whole problem. You keep reading entire phrases into his articles in a very self-serving manner. In fact, like bass traps, he’s saying that multiple subs make the EQ work better. This shoots your entire agenda of not using EQ at all completely out of the water. Wow, @pirad, you’ve basically destroyed your own arguments with Toole. Again.

My original statements, are and continue to be, one sub with bass traps and proper EQ is amazing. I know because I’ve measured and heard it. Further, good room acoustics make small speakers sound larger. They do this by controlling the resonant modes which make the bass sound flabby and boomy. So, again, the vector for the frugal audiophile who wants to limit his hardware purchases to me is clear:

Room acoustics --> Subwoofer --> DSP for EQ and integration


What you may be missing also is that DSP isn’t just about EQ. DSP also plays an important role in setting the proper crossover settings and delay, which JL Audio also points to. And, like Toole, I’ve seen and heard horrible, absolutely horrible sounding ARC. It’s gotten much better, and JL is one of the better brands. It is also FAR TOO EXPENSIVE. Really, besides the woofers, the main selling point of JL is how good they sound and how easy they are to install and have sound good.

So, given that the average audiophile is not a speaker builder, if they don’t have room for a swarm, a single sub, well placed, properly integrated to the room and speakers is really a great solution. Two is better.

The only area of contention really is how good automated systems are, and that as other acousticians have found, you can even fix unfixable dips with the right room acoustics.

And what if you don't want a sub? Again, room acoustics are where you start.

@noble100

I agree with Erik that a single sub properly positioned, with PEQ and DSP correction can provide good bass response at a single designated listening position but will likely result in poor bass performance at numerous other positions in the room.

What you are missing from my argument is bass traps. I never said EQ alone solves all issues, but rather that EQ and room acoustics are complementary.

In theory, you could fix all room modes with proper bass traps, but few of us are able to afford something akin to the Magico listening room.

The magic sauce is the use of both. The traps stop the ringing, the EQ corrects what’s left and you can get something damn good that works for multiple listening locations.

Of course, a true pro will measure several different listening locations and attempt to use an average to decide what to adjust.

Still, Toole’s argument of "how do we know what is right" holds true. Even after this, the use of a discriminating ear is very valuable.

Also, to reiterate, I have nothing against the swarm besides cost, complexity and space. :) I mean, as far as I can tell from reading it should sound great. It’s the cultishness of the idea it is the ONLY possible way to have good bass. It isn’t.  If you have the money and space for 4 subs, by all means, have at it, but don't compare it to a poorly integrated single sub as proof it is the only way to go.

Best,

E

Apparently we read different papers from two different universes, each with its own laws of physics. In your universe the definitions of physical states (eg. "steady state") follow circular logic.

@pirad

I’m not feeling very charitable. Did you not understand how Toole used the term? That may explain where your reading went awry. Right up at the top of the paper.

As a parting note: "room EQ" makes poor systems sound better in the listening spot by acting as an ersatz speaker correction technique.

Man, you really can’t read context can you? Like, at all. Toole writes a paper about how hard it is to judge a room response and you claim it proves vaccines cause autism, but later, you claim Toole never said anything.

Toole never really studied distributed bass, he left it to Welti. Geddes had the last word though.

So, you are bringing up Toole as your authority to prove Toole said you can’t fix bass problems .... but he didn’t really study distributed systems, so he couldn’t know, and therefore your use of the paper was to.... blow smoke.

Here, I answered fully this issue in another thread.


I used to work in motion picture equipment industry, including design, installation and set up of some of the best sounding motion picture audio gear in the world. I also make my own loudspeakers and do my own room EQ.

My views are pretty much the same as those posted by JL Audio, though as I posted elsewhere, I disagree with them in some nuanced ways:

https://forum.audiogon.com/discussions/me-vs-jl-audio-an-open-discussion?highlight=me%2Bvs%2Bjl%2Bau...

The problem you’re having rooze, and the mistake you’re making, is the same one I made and everyone makes and that’s following the conventional wisdom, because the conventional wisdom is WRONG! The conventional wisdom is based on the idea that because sound is waves and bass is waves then bass must be the same as midrange and treble. When its not.

That’s not the conventional wisdom, and not what I’ve seen anyone propose. The general solution, as written by and accepted by professional acousticians and installers, for getting deep bass in a room with moderate spend is bass traps + EQ.


http://ethanwiner.com/basstrap_myths.htm


My views and recommendations are also largely in line with what GIK Acoustics would recommend, so please, contact them directly and ask.

https://www.gikacoustics.com/

If you have lots of room, time and money, get more subs, and a custom room. Otherwise, I stand by my advice of using a DSP based solution along with appropriate room treatment and question your judgement and qualifications.

Best,

Erik

And I want to let go of this subject with another point:

The multiple sound problems Toole is addressing in this paper is going to be exactly the same with a swarm.

Best,


Erik

What is your definition of "steady state measurements"?

I’m using Dr. Toole’s, which is clear from his contrast with time-gated measurements.

Please note, this paper is from 2015, what changed since then in the area we are discussing?

My past experience in motion picture auditoriums goes back decades. I’m just utterly surprised RTAs are still used in a theater at all.

He discounts the claims made by the proponents of so called "room EQ". And the inadequacy of "room" bass traps is self evident.

You are missing the entire context of his paper. His paper is about how to set EQ, whether to use reference or house curves and if so why and how we could validate them. Essentially he’s asking how we get to neutral. He doesn’t say we can’t fix room modes.

It does not address small room bass modes, which are a catastrophic attack on anything like neutral. Again, others have covered this directly and precisely. He’s not talking about that at all.

His point if I may be allowed to paraphrase the good doctor:

"We don’t have a very good way of understanding how the ear brain mechanism perceives complex sound, so the idea of using either steady state or gated measurements to set the color is laughable."  The last part I think modern systems have started to get a little better at, at least for the bass and room gain, but as I said, it's basically personal taste converted to DSP code.

And again, I agree with everything he said. He’s brilliant and correct, and attempting to claim he discounts the use of bass traps, or EQ to fix problems is not in this paper. In fact, he’s asking HOW to use EQ.

First, I used to work in cinema sound, so thanks for sending me something so interesting, but the paper does nothing to contradict the earlier posts I made.

Toole is questioning and providing data for measuring and calibrating theaters, while comparing home and cinema speakers.

The issue of taming bass modes via bass traps and EQ is not exactly what he’s pointing at here, so much as the trouble with using steady state measurements which had dominated cinema measurements, which I’m very much surprised is still being done.

Let me jump into a section you quoted here:

It is a bold assertion that a single steady-state measure-ment in a room—a room curve—can reliably anticipatehuman response to a complex sound field. Such measure-ments take no account of the direction or timing of reflec-tions within the sound field. Time-windowing the measure-ment is useful to separate events in the time domain, butthese too ignore the directions from which sounds arrive

100% True!! But again, he’s addressing the overall timbre balance, not the taming or elimination of room modes which others have written of, which is very cost effectively handled by bass traps and EQ. However, making that sound good is my hobby and pleasure. :) Do so with two dozen woofers if you’d like to do it that way for yourself.

So what are we left with? Personal taste to attempt to assess how to set things, and that IMHO is really what makes a great room correction system vs. not. The two companies I know do a great job at this, fire and forget, are JL Audio and Dirac. I haven’t heard Anthem’s, but given they and Dirac allow for hands on customization I’m sure they’ll do.

And while this is all rather technical, and therefore fun, for me, I also want to follow Toole’s lead and jump out of the techncial to the subjective. Properly set up, a single sub with EQ and bass traps is nothing short of glorious. So not only have I read up on this, experimented and measured, but I experience stunning life altering bass without more than 1 subwoofer. This is why I’m so confident that the science and practice works.

What does suck is I’m not really sure how many other audiophiles can take this approach without an automated system. In that sense, the simple formulas for using 4 subs seems a lot easier for most.

Best,

E

It's 2020, who on earth uses steady state measurements??

When you EQ one sub, what you effectively do is ameliorate the modes situation at one spot (eg. your listening position) and make it worse elsewhere. It is easier to place the sub next to your armchair and delay it.

This is only partially true. With room tuning, you can take care of it all at once. Please read up on the proper use of EQ in partnership with bass traps.

And adding 3 more subwoofers to me is complexity. Three more subs than you would need otherwise, in addition to the signal cables. That’s definitely not for me and my home.

To be clear, I’m not advocating that there is only one possible truth to good bass. I am saying, religious fanaticism about swarms prevents us from looking at other very good alternatives. I worry that the fans of Swarms have gone from 1 bad subwoofer, to 4, and jumped all possible steps in the middle, so they discount them as inadequate, which is a shame in my view.

Distrubuted bass addresses room modes, probably with more success than other solutions.

Well, definitely not without it's own share of complexity and cost.

Not sure what we are discussing here with respect to infrasounds (<20Hz).

My statements about being able to get a sub flat to 16 Hz go back to something you said earlier:

The Swarm, when sealed, goes down to 18Hz

Meaning, again, a swarm is not the only solution to great bass in a room. I can solve the room mode problem, and get wonderful bass in the same scale as you claim for the Swarm with a single sub, bass traps and EQ.

The answer is the same as "what is the problem you are trying to solve with a swarm?"

Yes, mics can "hear" under 20Hz and visualize the measurements.
How does a "boomy" or "not boomy" infrasounds are visualized
in magnitude curves?

I can answer this question technically, but before I do, it seems to me that you feel like you are qualified make statements about the quality of bass, and the depth of the bass but I can't??

As you might surmise from my blog post, I make my claims based on measurements with OmniMic.

Best,

Erik

The Swarm, when sealed, goes down to 18Hz.

Impressive! I've gotten flat response to ~ 16 Hz with a single sub. Repeatedly. Not boomy.

In your post regarding Linkwitz you prove my point. The idea that only swarms can produce great bass is what I object to.

@jmpsmash

apologies if you have mentioned it. back to your original post. I wonder how big is your room?

The total acoustic space is about 12.5’ x 30’, divided lengthwise into a living room and a second kitchen/dining area.

6.5" may be good enough for a medium room, but might be a bit lacking if there isn’t enough travel to move enough air to energize a large room.

So, again, the point of the post is not that everyone will be satisfied with a small woofer, but to help buyers understand that even relatively small speakers can put out quite a bit, and that room acoustics matter a great deal. For my modest apartment, with the couch 9’ or so from the speakers this is plenty of high quality bass.  Which brings me to another point:

Good room treatment can make speakers sound BIGGER. Going with larger speakers in a bad room may in fact be a bad idiea.

No there is not. And there never will be.

There is a sense of Bass but not to real scale.

I think you missed the point of my original post, @ishkabibil :)

To appreciate what constitutes a good bass, one needs to experience a distributed subs system like the Swarm

Not at all universally agreed to.

https://www.soundandvision.com/content/are-you-putting-subwoofers-behind-viewer

Hi @noble100

It is the link in my first post. :)

Best,

E

I added a chart from Gravesen on my blog, which shows exactly how room gain affected one of his designs.

+1 for Soundocity's outrigger! Really makes setting up speakers a lot easier.

AMTs, not true ribbons.

Note though that they are cuts, not boosts. The point of the post was the speaker + room gain creates a lot more bass than we think. Also, don't discount the bass traps I have. :) It would be a much more complicated picture otherwise.

Best,
E

treating the room instead of trying to compensate the bad room with a limited speaker is the path to long term satisfaction ime

I agree.

Kenjit

I don't know what I like most about your posts, the personally insulting tone or the flat earth perspective you have on science and engineering.

Best,

Erik

Hi @adameos

Is there truth to the notion that a smaller bass driver (6.5” - 10” etc.) will be quicker sounding / more resolving than 15” drivers?

No, but that’s what we are touching on here. Less bass = low risk.

I’ve heard many biG horn / compression driver JBLs with 15”woofers that sound very fast and agile in the bass.

There is simply no substitute for surface are when it comes to deep bass and high output levels, especially in a test chamber or outdoors with no reflection points.

The trouble really is the room. Small rooms, untreated are much friendlier to smaller speakers with limited bass output. And that’s the blog post. :)

Thank you all for participating so actively, especially those who can share personal, specific experiences and who read the nuance in my original post.

I was thinking of something that I think has helped this discussion: I used a DIY speaker as my example, otherwise many would accuse me of shilling for a particular brand. At the same time, I don't mean to imply only this speaker can output this much bass in a modest listening space, I'm sure many others can as well.

BTW, anyone notice how damn smooth that bass response is??


Ty GIK acoustics and a semi-open room. :)

With room gain, I'm measuring into the mid-30s and it sounds it...very solid not muddy at all.

@Crustycoot

That's what I'm talking about. Smaller speakers can integrate a lot better into a room, and leave you more satisfied with less effort.  The combination of better matching the room gain, plus not disturbing the dragons in the depths (room modes) is a big big win for a lot of consumers.

There are a lot of ways of getting great, deeper bass in a room, but they don't come easy and they don't come cheap.


Best,
E

Just wanted to mention, I've taken a quick peek at the SS Ellipticor measurements on the same sight and the IM distortion is almost as good as the Purifi. :) 

A shootout of these high end mid-woofers would be fascinating.

Asked and answered:

https://www.stereophile.com/reference/1104red/index.html

The Purif measurements here made for very interesting reading:

https://hificompass.com/en/reviews/purifi-audio-ptt65w04-01a-midwoofer

In particular, nice to see that IM distortion measurements for drivers is still being used to good effect, since I posted an article about this here, but also the possibility for a 3-way speaker to improve clarity by removing IM distortion, and by extension, a properly integrated subwoofer.

But I hope everyone immediately stops doing 6.5" midwoofers with Mundorf AMT tweeters, tats my very own shtick. :)

Of course folks what we’re talking about here is what happens to a speaker in a room, or what Troels Gravesen calls "room gain." That is, the difference in a speaker’s response between the anechoic measurement, which is usually the -3 dB spec cited, and the completely room acoustic dependent response, which is what I measure in the blog post.

You can’t violate the laws of physics, and we aren’t. A speaker in a room sounds entirely different than it does in a measuring lab, and that’s where so many of our troubles come into play as we look for deeper, bigger bass.

The more of us see and know about it, the more audiophiles will get good buying advice, and more of them will be happier.

That’s the goal.

The Devialet cheats!!! :D


OK, so the two 7" probably have about the same effective area as a 10", but you are right, they have massive excursion capability, much more so than any other 7" speaker should have.

Subs when properly implemented
increase midrange clarity, solidify and increase soundstage dimension and
space.

Absolutely true.   The problem is always proper implementation.

and erik is wrong again.

A 6.5 inch woofer must not do bass. Its too small. You need big 15 inch woofers to do bass. And doing bass and mids is a horrible compromise. Erik is all wrong.

I've got the measurements that illustrate and prove my thesis.  You've got two hands holding air.

I have several of the Purifi Audio 6.5 inch drivers on order.

Very cool looking.  Would hate to have to replace the surround in 10 years though! :)


Let usu know how they measure @theaudiotweak .


Best,

E

To be clear: I am a big fan of subwoofers.  :) I have a 15" Hsu. I don't mean to advocate against large speakers, or against subwoofers at all.

What I do want to say is that the path to great bass starts with the room. Whether you are going to stick with a 2-way monitor, upgrade to larger or start adding subwoofers, a well treated room is the shortest path to bass nirvana than all other paths.