What year was this? If it was late 70s, this was only half the price of a top-tier boombox
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If I recall correctly, this is the original Mach One, which was released for sale around 1976. RS released 3 versions of this speaker over a span of about 8 years.
This original release had the catalog # 40-4024. Supposedly, this is the best and most sought after version. The woofer supposedly featured a rubber-roll cone suspension and a complex 3-way crossover with crossover freqs of 800 and 8,000Hz. The original price was $199 as indicated in your catalog pic.
I never auditioned or actually saw this version. I began looking to buy a pair of speakers a few years later.
The second version is also well sought after. It is catalog 40-2040a. This is the version I owned. I paid $259 each (inflation, I guess).
The 2nd version differed slightly from the original. The cone surround was a thick, wide foam roll, not rubber. The crossover points were changed to 1,200 and 5,000Hz for mid and tweeter.
I very much enjoyed those speakers. Especially when listening to electronic or classical music. A very warm sound. Good bass extension. Very large sound due to the big mid horn. Detailed and articulate. I like the transient response of horns and sealed woofers.
The 3rd version, I think, was an Optimus and not a Realistic any more. But, don't quote me on this. The catalog number was completely different. Unlike its predecessors, it was a bass-reflex rather than a sealed acoustic-suspension. I auditioned them more than once. I thought they sounded awful. The warm balanced tone was gone. So was the tight bass extension. They were just not the same. I am not a fan of bass-reflex. They can sound great or terrible. They can really color the sound.
To my knowledge, this final version is not considered collectible.
Several years ago, during the pandemic, I built a pair of 'retro' Mach One speakers, based on my memory and pics. Rather than buy 40+ year old parts, I went a different route.
The woofer I used is an actual replacement for the Mach One, made by GRS. It looks and feels identical. Sound quality is very similar, as far as I can recall. These replacement Mach One woofers also feature a vented voice coil for reduced heat and compression, which is an improvement. The magnet is large, similar to the original, as far as I can recall. I think the magnet is around 30-35 oz.
I then found a midrange horn lens of similar size to the original, and which has a lip which extends past the cabinet, just like the original. It is a Nippon horn lens. It is also sold under other brand names, fyi. It is bi-radial, which I believe is an improvement over the original Mach One horn. Its horn lip extends further out past the baffle as well. Bi-radials are supposed to deliver better vertical as well as horizontal projection. I honestly don't know if that claim is true. I had a pair of bi-radial horn tweeters, from RS, back in the day and I was not impressed at all lol. But these mid horns sound good, to me.
The mid driver is a Goldwood 1.5" compression type with a phenolic dome, which matches the original driver, almost exactly, down to the bullet phase plug. The magnet is larger, at 20 oz vs 10 oz for the original driver.
For a similar sized tweeter, I used a pair of peerless conical horns. They claim a 25Khz upper response which matches the original tweeter claim. But, the tweeter I used has a die-cast aluminum body and a much larger 20 oz magnet, plus it is ferro-fluid cooled.
I then added a mid and tweeter L-pad, to simulate what the original Mach One offered.
I experimented with a crossover I put together. What finally works is a 12dB/octave crossover at around 2,000 and 8,000 Hz. No crossover for the woofer. According to its spec sheet, the replacement Mach One woofer has a natural rolloff right around 1,400 Hz. The crossover I made for the woofer seemed to affect its output and tone. I prefer it without the crossover.
Cab is 5/8" particle board with a simple vinyl laminate. Eventually, I will get around to covering them in a walnut wood laminate, as was the originals.
I really like their sound. Full bodied, warm and detailed. I listen only in stereo mode.
But, not everyone likes horns. Each type of driver has its own sound or color. I built these because I was always sorry I sold mine. They remind me of a fun time. Nostalgia, you know.