Mixcubes

Hi arnyk.  Nice to meet you. I think this is our first conversation.  

I posted the article to this thread for review.  I've never claimed to be an expert in audio or recording.  In that light, I don't doubt that I've committed mistakes in my exposition.  The fundamental premise of my position is that having a mixcube is useful and fun.  Also, top 10s etc are popular formats for infotainment.  Additionally, and as is common for me (and something I take a full ton of heat over), I tried to make it entertaining at the expense of 100% validity.  

That being said I'd love to hear your critique.  I'm certainly not above learning or editing my posts

-m

Just to clarify, Arny is a bona fide audio expert with at least as many years experience as me.

Here's the text you provided:

"No ports. This means more accurate low-end. The holes (ports) on your speakers are meant to artificially extend the low-end response of your speakers. The problem is you get a resonant bump at the cutoff (distortion) and, because your boat has a hole, your transient response suffers as well. Mixcubes are sealed so your kicks are punchier and you’ll know exactly how thumpy they are."

Here's what I take exception to:

"No ports. This means more accurate low-end."

If that's true why do some (highly-regarded for their accuracy) studio monitors like the Mackie HR 824's have ports? The true answer is very obvious: Ports are not necessarily a detriment to sonic accuracy. In fact, the truth is the exact opposite of what you said: Ports if properly implemented can be used to increase the sonic accuracy of a speaker. the real problem with ports is that they were generally badly designed until some guys names Theil and Samll figured out the theary and implemented a relatively simple scheme for exploiting the theory.

Ports were invented in the mid-1930s (called "Bass reflex") if memory serves, and they were widely well understood after the publication and acceptance of T&S's papers in the 70s and 80s. So there were about 40 years of congenitally bad ported speakers being produced. Some designers are still not exploiting this well, so we still have a lot of badly designed ported speakers. Of course, as the HR824's prove we also have some very good ones.

Yes, HR824's have ports, or more consistent with what you see, they have a large passive radiator which is the exact acoustical/mechanical equivalent of a port. To clarify, the key component of a port is the mass of the air in the port, and a passive radiator provides a more compact but also more expensive equivalent of that air mass with a weighted cone. The equations are the same if adjusted for the implementation.

So, then when you equate ports with holes, you are making another omission because many speakers have the exact acoustic effect of a port, without having any holes. :-)

Then we have this: "...(ports) on your speakers are meant to artificially extend the low-end response of your speakers."

Obviously, you have a very personal and specific definition of what's artificial and what's natural. My definition of natural allows anything simple and passive, in which case ports and passive radiators are natural. Your definition seems to be very agenda-driven and as I've already shown, that agenda does not agree with reality.

"The problem is you get a resonant bump at the cutoff (distortion) and, because your boat has a hole, your transient response suffers as well."

The resonant bump doesn't have to be there just because there is a port (that's what good design is about), and its possible to have a bass bump with a sealed box. So, that's two mistakes in one sentence!

I might add that one of the most common sources of bass bumps is the room, and ported speakers by naturally extending the bass response possible in a given box, can result in a speaker that excites a room resonance worse basically because it is doing its job better. Do you blame the speaker for doing a better job or do you put the blame on the room where it belongs? Yes, I can subjectively improve a room by bringing in a more bass-deficient speaker.

After contemplating this problem for about 40 years (remember, I've been an audiophile for 57 years and that goes back to 1959 when almost all ported speakers were misdesigned because nobody knew of a better way than that because the mathematical solution was still like 10 years down the road, I've decided that the "One size fits all" solution to interfacing speakers and rooms is to position speakers for smoothest possible response subject to other practical considerations, and then adress whatever problems are left over with electrical equalization.

And when you get into the basic justification for mixcubes, I get that because I was a recordist/producer/mastering engineer/ distributor for 12 years, up until I retired. My product was played on everything from portable digital players to boomboxes to great stereo systems to crappy ones to car stereo systems of all kinds. The problems of making a mix that translates well in all those places was on my agenda, big time. The fact that broad good mix translation was a serious problem was there right before me. Like you, I handled it (the old fashioed way) by having what I felt were representatives of my common target audio systems on hand, and moving a mastered recording around to see how it worked in every context.

In the above context I would probably reject the Mixcubes because they weren't crappy enough to be representative of what my recordings faced. I suspect that the effect of a mastering torture test would be well-addressed by some clever DSP programming that would add various kinds and amounts of linear and nonlinear distortion on demand. Put the selector into "Boom Box" and listen. Put it into "Great home audio system" and listen. Put it in "Crappy car audio" and listen. etc.

Arny,

Thanks for the brief history of loudspeaker ports, I remember most of those events in the advancement of our collective understanding and it's a nice trip down memory lane .

Hexspa, I'm sure all that info can be studied and learned in great detail but I think ones perspective is different if one has lived through it all... as long as one has at least paid some attention, and that does make it a little easier

There are tons of articles and software for Thiele/Small design if you're interested, so it's easy to get started. Designing a ported cabinet is fun and easy and with the right software, you can get graphs and results without building anything. You can play around with the port dimensions and enclosure volume and see how specific drivers perform. Quite a few years ago I downloaded an excel spreadsheet using macros for free and it's pretty handy but there are probably better solutions out there by now.

Cheers,
Rock

I'm so glad I opened this can of worms.

My digestion will never be the same.

Seriously though - I've exposed a weakness in my understanding of something I take for granted.

Pain heals.

Thanks for the responses. I'll be sure to take some time to establish a better understanding of this area.

-m

Do you mean why people think I'm a dick? 

The forum gave me that name.  I just do my best to uphold it.  

-m