Edgar

I certainly hope that this doesn't lead to another Audiophile Myth. 🙂 Using non-audio wires for audio? Blasphemy!

I would keep the woofer wires as physically distant from the midrange and tweeter wires as the construction permits. Woofers carry the most current, often by a considerable amount.

If "7C" means seven conductor, then you can think of it as three pairs plus one extra. Just don't be tempted to connect all of the negative wires together -- some amps will tolerate this, but many will not. Ideally you would use three twisted pairs, because without the twists there can be crosstalk between the signal pairs due to their close proximity. Maybe experiment to see if it's objectionable -- I suspect that, with such small signals and short distances, it won't be.

The blades no longer match their reflections in the canopy.

Though it may no longer be true, for a long time one indicator of true Baltic Birch (from the Baltic region) was that it was only available in 5'x5' (1525 mm) sheets. https://www.woodworkerssource.com/blog/woodworking-101/tips-tricks/your-ultimate-guide-to-baltic-birch-plywood-why-its-better-when-to-use-it/

One theory is that the woofer enclosure should be so rigid that any wall resonances occur at frequencies higher than the upper frequency of the bass driver. By contrast, the midrange enclosure should be "floppy" enough that any wall resonances occur below the lower frequency of the midrange driver. The text that @Travis In Austin quoted supports this theory, and emphasizes that those requirements conflict when the driver handles both bass and midrange.

Or not enough difference in sound performance to overcome the advantages MDF brings to the design, whatever they may be.

Don't forget that the definition of "optimum" depends entirely upon what one is trying to optimize. Roy, like all engineers, has to balance a number of performance criteria, including price, measured audio performance, manufacturability, shipping costs, availability of raw materials, and so on. Even "cost is no object" designs are subject to this same balancing act.

https://www.grainger.com/product/60AG40 https://www.farmandfleet.com/products/967444-woods-yellow-jacket-4-outlet-metal-power-block-adapter.html

It is my understanding that woods used for stringed instruments are selected for their contribution to the tone, while loudspeaker enclosure materials are selected for their lack of contribution to the tone.

Something doesn't look right. For Fs to decrease by that much, the suspension compliance would have to increase by 83% [Fs is proportional to 1/sqrt(compliance)]. That's a really big change. I have a NOS quad of EVM-12L. Maybe someday I will conduct an experiment, if I can find the time.

From a purely objective standpoint, I agree with most of what you say, too. In this context, it's just not necessary to be purely objective.

And it is! This is a hobby, not rocket science. A good portion of the enjoyment of the hobby is pride of ownership. And that is based largely upon subjective opinion. And often that means impressing others as much as impressing one's self. And often that means deluding one's self as much as deluding others. Whenever a friend asks me what I think of their audio system, I always answer with, "Do you like it? Yes? Then it's great."

Be careful; that was an opinion, not a statement of fact. Assertion without proof that something is not audible is an equivalent logical fallacy to assertion without proof that something else is audible. In fact, proving that something is audible is a lot easier than proving that it is not.

Here is another interesting bit of information: PLYWOOD vs MDF For Speaker Building - Tests Show Surprising Results

I don't have sufficient breadth of experience to comment, but I found this to be interesting.

True, but arguing about what other people cannot hear is futile, or hubris. I am willing to comment only on what I can or cannot hear myself. I am sometimes amazed by what others can verifiably hear ... and I have, on rare occasions, been able to similarly amaze others with what I could verifiably hear. Often it boils down to knowing what to listen for.

My testing, if you can call it that, was very informal. I had a pair of NOS Electro-Voice EVM-10M (similar, if not identical, to Klipsch K-41) that had never been installed. I removed them from their cartons and measured the Thiele/Small parameters. Then I hooked them in parallel with the woofers on my main system, put them in another room so that they wouldn't interfere with the SQ of my listening room, and ignored them for a week. They were run without enclosures, and received whatever signals the woofers of my main system received. This was a biamplified system, crossed-over at 180 Hz and equalized flat to 27 Hz, so there was a fair amount of boost below 40 Hz. After a week of normal listening to everything from Pink Floyd to television programs, I measured the T/S parameters again. I don't recall the exact numbers, but there were changes and they were very small, on the order of a couple of percent. Make of that whatever you please.

I was wondering the same sorts of things. Another way of looking at it is, "100 percent is (only) 3 dB". That means that driver parameters can change by a whole bunch and still yield just a 3 dB difference. And as I showed in my WinISD model previously, even a 50% change in compliance resulted in just 1 dB difference.

Can't say that I did. Well, you learn something new every day.

"Acid test" comes from testing samples of ore to determine whether they are gold. Gold does not dissolve in nitric acid, but it does dissolve in aqua regia.

I have a 49 year old Brooks saddle on my mountain bike. I'm pretty sure that it's broken-in.

At my former employer (I'm now retired), we set up a test of a dozen or so capacitors operating on the medium voltage line. These were special film capacitors designed to face 7200 VAC @ 60 Hz continuously, so we were testing them for premature failure and any changes in their performance parameters. Over the first month their capacitance changed by a few percent, and then stabilized. Now audio capacitors will never face anything like 7.2 kV, but the example does offer at least some evidence that capacitors "break-in".

If you get excessive wind noise when riding your bicycle, then you must be very fast. 🙂 Old adage among bicyclists: "Anybody who rides a circular route and complains about a headwind the whole way is either very fast or has a bad attitude."

I think we've established that driver break-in does occur, and that it's probably audible. We still haven't resolved whether it takes 20 minutes or 200 hours.