Cable Conditioners

[CatalinaWOW]

The main issue as I see it with this claim, is that lead acid batteries have a higher impedance than big electros...

So you are complaining about the technical ignorance of the writer who described the solution.  Impedance isn't the fundamental issue, it is the next roadblock after you solve the fundamental problem. 

I agree that there are many audio fanatics who talk way above their weight class, and many who dabble in circuit modification (I can't really call it designing) well above their weight class.  But when these people talk their mistakes are the mistakes of ignorance, not the outright fairy dust lies that many in the field promote.  The line can be fuzzy at times between the incompetent and the dishonest, but I think the article you reference was dealing with a fairly competent designer and a less competent writer.

If you want to science this just put your Spice simulation to work on a 30 Hz 300 W load (300 W is an extreme, but remember speakers were less efficient once upon a time) on a 50 or 60 Hz mains supplied power system.  Limit yourself to the topologies available at the time of the article (center tapped transformer with dual rectifiers or single output transformer with bridge rectifier either one followed by a low pass filter consisting of the impedance of the transformer/rectifier system and a capacitor of a few tens of thousand microfarads).  How much harmonic distortion do you see?  How much are you willing to accept?   Where does capacity dominate and when does the source impedance become the dominant source of distortion?

Your late 80s article represents the thinking of an audio designer in the mid-80s given publishing delays.  Remember that switching power supplies were just starting to be a thing in the 80s, and switching noise was not a solved problem.  May seem dumb now, but using batteries as an alternative to giant capacitors was a trick used in many fields.  I have come across several instances.  Makes for an interesting Spice model.

[AVGresponding]

As I recall it was a premium mainstream magazine, What HiFi maybe. I expect better levels of knowledge from that kind of publication.

Supercaps (1-2.2F) were starting to appear by that time, mostly from my recollection aimed at the car audio market.

Using lead acids isn't a horrible idea, it's a good one, if somewhat high maintenance. At the time gel types were rare and expensive, and given the low probability of the DC rails in the amp being at the correct float voltage for a string of 12V batteries, that means using individual cells to try and get close.

The local authority I work for still has quite a few properties with wet cell central battery units for the emergency lighting systems, and those 50-odd long strings of Plante cells are a bastard to keep topped up.
Not to mention the fact that improper charge voltage/current can have serious consequences... hasn't happened to me, but a colleague topped half a string up, went back the next day to finish (he'd run out of de-ionised water), and found the inside of the door to the battery room studded with shards of battery casing. Fun times!