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Realistic Optimus-1 (KLH-6 copy)

HTHMAN

HTHMAN

Super Member
I used to own the Realistic Optimus 5B speakers that were a blatant KLH-5 copy. Those were great sounding speakers, but sold them because they did not fit into my wife's decor.

I was on Craigslist and saw a pair of Optimus-1 speakers listed in town for $10. I could not get there fast enough. Those were the first and one of the best of the good Radio Shack speakers. Their ad from about 1970 said that they copied the sound of their favorite $134 speaker at 30% less cost. They would not mention the brand, but the excellent KLH-6 by coincidence was selling for $134. Both were acoustic suspension with a 10" woofer (that look very similar) with a 2-way crossover. The difference was that KLH used 1 tweeter and Radio Shack used two. The speaker uses a 3-way switch to adjust the tweeters for normal, low and high levels.

I cleaned them up and hooked them up today. Wow!!! These are great sounding speakers. This is without a doubt the best buy I have ever gotten on a set of speakers. Here are some shots of them.

Optimus-18.jpg


Optimus-17.jpg


Optimus-16.jpg


Optimus-15.jpg


Optimus-14.jpg


Optimus-13.jpg


Optimus-12.jpg
 
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Those look to me to be more like the KLH 17 or 23 cabinets. And, didn't the 6's have a 12" woofer?

dew.
 
I have a set of the Optimus ones however mine have the black Grill cloth. Except for the grill cloth they are identical to the set you have and yes they are great sounding speakers.
 
Very nice Optimus 1's! Those look like early versions of the woofers from the 5's and later the Optimus 9's. I love those woofers, I use them in the bass bins you see in my avatar.
 
Yeah, I should have got the Optimus-1B instead of the Optimus-2B back in 1975. I was too cheap/poor to spend an extra $40.
 
I agree, they look more like KLH-17s. They're in really nice condition, too. I wouldn't look to flip them for a profit. However nice they might sound and look, you aren't going to bring in a lot for vintage Optimus speakers. Best to sit back and enjoy the music because you aren't going to find much else for $10 that looks like that (and makes music instead of sound).
 
dew042 said:
Those look to me to be more like the KLH 17 or 23 cabinets. And, didn't the 6's have a 12" woofer?

dew.
Click to expand...

The KLH-6 was a 2-way acoustic suspension with a 10" woofer. The KLH-5 was a 3-way with a 12" woofer, 2 mids and 1 tweeter. The Optimus 5b (which I owned) was a copy of that speaker. To quote Radio Shack in the 1970 catalog "We designed around the sound of our favorite speaker (selling for $134.00)". The price of the KLH-6 in the 1967 Radio Shack catalog (back when they sold Scott, Fisher Marantz, Electrovoice, Wharfedale etc) was in fact $134. The KLH-17's were also a 2-way with a 10" woofer in a smaller cabinet (not sure if they used the same drivers) and sold for $69.95 in the same catalog. The Optimus-1 cabinet is closer in size to the KLH-6. What the Optimus 1 really looks like is the AR3, but that had a 12" woofer and was a 3-way system. Sure wish I would have bought those when they were $200 as you pay many times that now.
 
The KLH 17 is not quite a quarter of an inch taller and one quarter of an inch wider than the Optimus 1B. The Optimus 1B is about two inches deeper than the KLH 17. The frame of the woofer in the KLH 17 is about an eighth of an inch larger than the frame of the woofer in the Optimus 1. The cone on the KLH is about one half inch smaller than the cone on the Optimus.

I should mention that the box measurements were taken from an Optimus 1B, while the woofer measurements were from a woofer from an Optimus 1 no B.
 

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You got a great deal! My first good speakers were Optimus 1's. I got the white grille, like yours and my Dad got the black grille. He still has his. The friend I sold mine to still has his. When we bought them, they were on sale for half price; $60 for the pair. The deal was actually "buy one for $60, get the other one free." Silly. I have a friend with the KLH 17's and the Optimus 1 cabinet looks just like it, with that extra strip on the front. The KLH 6 had at least 2 versions. The earliest had a 12" woofer and the drivers were epoxied in, so you could not service the cabinet. The later version, which I had, used a 10" woofer, and the drivers were not epoxied in.
 
Is it possible that the two smaller speakers on the Optimus are not identical high frequency speakers? Could one, perhaps, actually be a midrange - powered on the same circuit as the tweeter and thus using a 2-way crossover?
 
Hey guys - an easy trick to fix those dented tweeters... First, get a simple drinking straw. Then, lightly "wet" the dented dome with whatever u feel like. I used a dab of alcohol with my finger. Then, with the straw in ur mouth, suck as hard as you can with the other end of the straw as CLOSE as possible to the dome, so its nearly air tight. Easy as pie! I used this method on some seemingly impossible Kenwood phenolic tweeters... and theyre fine now! I also did it on a pair of old Nova/Optimus speakers.
 
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rmeade said:
Is it possible that the two smaller speakers on the Optimus are not identical high frequency speakers? Could one, perhaps, actually be a midrange - powered on the same circuit as the tweeter and thus using a 2-way crossover?
Click to expand...

I replaced both of the tweeters in mine once, in warranty. They are identical.
 
I saw a single 1B? in excellent condition the other day. If there had been a pair I would have picked them up and been able to add to this post. It might still be there if anyone in Central CT area is interested PM me for the location.
 
absolve2525 said:
Hey guys - an easy trick to fix those dented tweeters... First, get a simple drinking straw. Then, lightly "wet" the dented dome with whatever u feel like. I used a dab of alcohol with my finger. Then, with the straw in ur mouth, suck as hard as you can with the other end of the straw as CLOSE as possible to the dome, so its nearly air tight. Easy as pie! I used this method on some seemingly impossible Kenwood phenolic tweeters... and theyre fine now! I also did it on a pair of old Nova/Optimus speakers.
Click to expand...

I will try that on that dust cover on the tweeter. Sure beats picking at it with a needle. I have never understood why people find it necessary to poke the dust covers with their fingers. Thanks for the tip.
 
The speakers in the 1975 catalog were Optimus 1b's. The ones I picked up were about 5 years older and at least the woofer was different.
http://www.radioshackcatalogs.com/catalogs/1968_small/ page 18
I used to have a set of Optimus 5b's that I sold a couple months ago that were fine sounding speakers. Since I no longer have them, I can not do an A/B comparison, but I seem to get better imaging with the 1's than I did with the 5b's. Perhaps someone who has/had both can chime in on the sound comparison. Also what people think of the 1's vs the 1b's and the 5's vs the 5b's. To me, the drivers in the b models looked to be a little more cheaply made.
 
The "B" drivers are a homage to efforts at cost cutting.
We had both Optimus 5's and and 1's in stock when I was a Radio Shack manager.
The Ones image better like you suspected.
Also,
I think a better crossover would help the Optimus 1 a great deal.
I would like to see the T/S parameters for the drivers in these.
 
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