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Vintage loudspeaker musing: those boomy 1970s sealed box loudspeakers -- and a suggestion :)

mhardy6647

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I realize that some of y'all are fortunate enough not to remember the 1970s. This thread topic may, or may not, be for you! ;)

I was just reading a thread at audiokarma which contained a link to an "explanation" of sealed (and, by implication, acoustic suspension -- as opposed to other sealed box alignments) vs. ported loudspeakers. I share the link, which, at a quick read, is almost embarrassingly misleading :rolleyes:


That's not, actually, what this post is about! :cool::facepalm:
But that blog post from "Fluance" did get me thinkin' about the notion of sealed boxes that do boom (or, at least, have a midbass hump), which led me to reflect on the 1970s trick of putting too large a woofer in a too small sealed box. And that is what this thread's about! :)

Two companies in particular come to mind for this particular design trope: Radio Shack and Sansui.

Radio Shack produced a number of sealed-box loudspeakers like this, the most salient (and perhaps the most egregious) example being the (in)famous Mach One.
1678120520422.png

source: https://www.radioshackcatalogs.com/flipbook/1976_radioshack_catalog.html pg. 47

The other once-common implementation of big woofers in small boxes was a proliferation of models (many sold to US servicepersons by military PXs) from the big-name Japanese audio companies starting in the late 1960s. These products often featured many different kinds and sizes of drivers and, due to their Asian source and Byzantine complexity, are nowadays often referred to generically (and somewhat derisively) as Kabuki speakers in some circles.

The sine qua non of such loudspeakers was indisputably ;) Sansui. From the late-'60s to the mid-'70s, Sansui marketed a bewildering array of stunningly unsubtle "Kabuki" loudspeakers.

byvLpUm.png

source: https://forums.stevehoffman.tv/thre...nese-atroicities-of-the-20th-century.1148633/

So -- here's where I am goin' with this. :) My recollection is that many of these loudspeakers suffered from (among other audio shortcomings) the lumpy-bumpy midbass bloat that was perceived by many in the marketplace in that era as bass. It might be interesting to see some modern measurements of one or two of these atavisms. :)
Perhaps unbelievably, I cannot offer up one for testing. Even I have my limits ;) and there is nary a Kabuki in my haphazard collection.

... but maybe one of you, ideally, out on the West Coast, does. :)

Any thoughts anyone'd like to share on the topic, or the performance, of this class of loudspeakers that were doubtless designed to impress?
 

RobL

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I had a pair of 4024a Mach 1’s years ago. I finally replaced them with a pair of Paradigm Monitor 7’s and the improvement wasn’t subtle, lol.
Boomy bass and screechy midrange is how I would describe the Mach 1’s now, at the time I thought they were fun playing 70’s and 80’s rock… and they looked bitchin’. :)
 
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mhardy6647

mhardy6647

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I had a pair of 4024a Mach 1’s years ago. I finally replaced them with a pair of Paradigm Monitor 7’s and the improvement wasn’t subtle, lol.
Boomy bass and screechy midrange is how I would describe the Mach 1’s now, at the time I thought they were fun playing 70’s and 80’s rock… and they looked bitchin’. :)
[emphasis added]
I believe you just crystallized the "Mach One user experience" -- to (mis)apply some modern jargon ;)

I'd be curious to see FR, distortion, and directivity data for a Mach One (any morph thereof)... and/or any member of the Sansui kabuki family (or Pioneer, Akai, Kenwood, etc., etc. variations on the theme). :)


index.php
 
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fpitas

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If stuffing the crap out of them with waste cotton doesn't help, then you might need to use an aperiodic vent to tame the hump.
 

fpitas

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I realize that some of y'all are fortunate enough not to remember the 1970s. This thread topic may, or may not, be for you! ;)

I was just reading a thread at audiokarma which contained a link to an "explanation" of sealed (and, by implication, acoustic suspension -- as opposed to other sealed box alignments) vs. ported loudspeakers. I share the link, which, at a quick read, is almost embarrassingly misleading :rolleyes:


That's not, actually, what this post is about! :cool::facepalm:
But that blog post from "Fluance" did get me thinkin' about the notion of sealed boxes that do boom (or, at least, have a midbass hump), which led me to reflect on the 1970s trick of putting too large a woofer in a too small sealed box. And that is what this thread's about! :)

Two companies in particular come to mind for this particular design trope: Radio Shack and Sansui.

Radio Shack produced a number of sealed-box loudspeakers like this, the most salient (and perhaps the most egregious) example being the (in)famous Mach One.
View attachment 269895
source: https://www.radioshackcatalogs.com/flipbook/1976_radioshack_catalog.html pg. 47

The other once-common implementation of big woofers in small boxes was a proliferation of models (many sold to US servicepersons by military PXs) from the big-name Japanese audio companies starting in the late 1960s. These products often featured many different kinds and sizes of drivers and, due to their Asian source and Byzantine complexity, are nowadays often referred to generically (and somewhat derisively) as Kabuki speakers in some circles.

The sine qua non of such loudspeakers was indisputably ;) Sansui. From the late-'60s to the mid-'70s, Sansui marketed a bewildering array of stunningly unsubtle "Kabuki" loudspeakers.

byvLpUm.png

source: https://forums.stevehoffman.tv/thre...nese-atroicities-of-the-20th-century.1148633/

So -- here's where I am goin' with this. :) My recollection is that many of these loudspeakers suffered from (among other audio shortcomings) the lumpy-bumpy midbass bloat that was perceived by many in the marketplace in that era as bass. It might be interesting to see some modern measurements of one or two of these atavisms. :)
Perhaps unbelievably, I cannot offer up one for testing. Even I have my limits ;) and there is nary a Kabuki in my haphazard collection.

... but maybe one of you, ideally, out on the West Coast, does. :)

Any thoughts anyone'd like to share on the topic, or the performance, of this class of loudspeakers that were doubtless designed to impress?
Well...when you can only afford a tiny magnet woofer and a small enclosure, the midbass hump is inevitable. It is true some people liked it.
 
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mhardy6647

mhardy6647

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Fixing them would cause their value to plummet, I reckon. ;)

Mind you, my expectation of their FR in the bass is strictly speculative -- I reckon that they tend to be underdamped (Q > 1) but I don't know that.
I would also be interested in the directivity of, e.g., the Mach One -- even if only in the way that one's is interested in observing the scene of a gruesome accident as one passes by on the freeway :facepalm:
 

fpitas

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Fixing them would cause their value to plummet, I reckon. ;)

Mind you, my expectation of their FR in the bass is strictly speculative -- I reckon that they tend to be underdamped (Q > 1) but I don't know that.
I would also be interested in the directivity of, e.g., the Mach One -- even if only in the way that one's is interested in observing the scene of a gruesome accident as one passes by on the freeway :facepalm:
I suspect your deepest fears will be confirmed. It was a time when boomy, shouty and screechy were all desirable traits :)

Those horns have always scared me, just looking at them.
 
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mhardy6647

mhardy6647

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Oh. :cool:


index.php


I mean, this is cool -- but the MC-1000 isn't cut from quite the same fine cloth as the might Mach One! ;)

I suspect your deepest fears will be confirmed. It was a time when boomy, shouty and screechy were all desirable traits :)
Yeah -- I owned a pair of 1974 Cornwalls. For longer than I am proud to admit, in hindsight. In fairness, I was perpetually trying to improve the Cornwall user experience. Turns out the best tweak is to sell them to someone else, though. Just took me a decade to figure that out.
 

fpitas

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The MC-1000 isn't too scary, no, but lots of slope. Might sound kind of dark etc. Best speaker in the world? Maybe the best one in the room at the time :D
 
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mhardy6647

mhardy6647

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I had a pair of dump find MC-500s. They were actually perfectly OK. R/S only really missed the boat big time when it came to their large loudspeakers, in my experience. :)
 

fpitas

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I had a pair of dump find MC-500s. They were actually perfectly OK. R/S only really missed the boat big time when it came to their large loudspeakers, in my experience. :)
Probably because big speakers need relatively expensive drivers to sound good. I have a feeling R/S was very cost conscious.

Having seen my share of big drivers from that era, the norm was a 10 oz hamburger magnet as used on smaller drivers. No, it wasn't a good idea. But it was cheap.
 
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jkasch

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My experience with sealed 70's speakers were of the east coast variety. Advent, EPI, Boston Acoustics, and Cizek. I found most of the ported designs boomy in comparison. I didn't have much exposure with the poorly executed examples cited above.
 

audiofooled

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I suppose the application for those were for party purposes. Grab your booze, keep the tweeter knee to hip level, and walk around to find that chest thump! And you don't even need a lot of power when your woofers are coupled to the hardwood floor!
There will always be a market for boom boxes, and bad music to make them shine. The difference nowadays is big ports tuned for one note bass, granted lower in frequency and lots of LED's :p
 
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mhardy6647

mhardy6647

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My experience with sealed 70's speakers were of the east coast variety. Advent, EPI, Boston Acoustics, and Cizek. I found most of the ported designs boomy in comparison. I didn't have much exposure with the poorly executed examples cited above.
Right. Villchur, Kloss, et al. designed systems for critical damping.
Others -- did not. :)
The small magnet drivers @fpitas mentioned would likely enhance the "misfit" of the crop of loudspeakers I've invoked in terms of (under)damping (Qtc > 1) ;)
 
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mhardy6647

mhardy6647

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I suppose the application for those were for party purposes. Grab your booze, keep the tweeter knee to hip level, and walk around to find that chest thump! And you don't even need a lot of power when your woofers are coupled to the hardwood floor!
There will always be a market for boom boxes, and bad music to make them shine. The difference nowadays is big ports tuned for one note bass, granted lower in frequency and lots of LED's :p
There's a thread that's active even now -- amusingly enough.
 

ed308

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Had a pair of the large Advents and JBL L100. Loved both and wish I’d never sold them for $100, especially the L100s.
 

restorer-john

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What those giant 15/16/17" multi driver speakers had was efficiency. In spades. Numbers modern speakers could only dream of. Those Sansuis pictured above were 100dBSPL@1W/m. And that 1W is 2.83V over 8R, not modern day cheating 1W of 2.83Vover 4R which is actually 2W.

So these speakers were insanely efficient and handled a ton of power. Exactly what the 1970s demanded as amplification was expensive. They would do parties with a 30wpc amplifier, whereas some of these speakers people salivate over these days, have real numbers below 80dB when referenced to 1W at their nominal impedance.

Some of those monsters sounded really good, most sounded like somewhat refined PA speakers. The Mach Ones were actually quite good, the Mach Twos were better. Fun speakers for proper music- no girl and guitar on a 5" two way stuff. Dad has a pair in their boxes in a cupboard someplace. As for the JBL Century L100s, the less said the better. I listened to a pair for exactly two days before selling them on. Nuff said.
 

audiofooled

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There's a thread that's active even now -- amusingly enough.

That's not half bad, but I meant 1,21 jiggawatts PMPO distortion factories, such as this:


If you care to watch, it is clear that when you are turning the volume dial you don't increase SPL, only distortion. It seems that manufacturers know a thing or two about psychoacoustics ;)
 
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mhardy6647

mhardy6647

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I still think it would be fun for @amirm to measure the performance of a Mach One. :cool:
(although, unfortunately, I cannot enable it)
 
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