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 Post subject: Re: Realistic Optimus 1 Speakers--Crossed Over So Low ?
PostPosted: May Mon 18, 2015 7:59 pm 
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the dome would have to be very shallow. these are front surface mounted and i believe there is no 'recessed' cutout for the ring to mount deeper into the front baffle.

other than the two-way optimus and nova systems where the HF drivers are 8 ohms, the two tweeter/midrange combinations are either 4 or (maybe) 16 ohms (i can't remember if RS used 16 ohm tweets).

even the newly acquired (totally fantastic) opitmus 5's that i have which use a single tweeter for the HF, it is 4 ohms. these use two midranges in series or parallel.

so, if any other tweeter is used except for original (which i absolutely love) they will need a an audio grade, non-inductive resistor in parallel or series to make the 8 ohm replacement the original tweeter's impedance.

steve

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 Post subject: Re: Realistic Optimus 1 Speakers--Crossed Over So Low ?
PostPosted: May Tue 19, 2015 1:07 pm 
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Wouldn't replace the original tweeter. Just add a dome tweeter and add a low pass filter to the original tweeters.

Could find a press fit dome tweeter and install that.


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 Post subject: Re: Realistic Optimus 1 Speakers--Crossed Over So Low ?
PostPosted: May Tue 19, 2015 4:43 pm 
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In my Nova 7B's, I replaced one tweeter with a 4" foam-edged full-range and the other with a Yamaha carbon-fiber dome. That was about 6 or so years ago and the speakers are currently stored. I had to pull 'em out and remove the grilles so I could remember what I ended up installing! ;) I probably made some changes to the crossovers or replaced them, but I don't recall what I did, since I was doing the same things to three other pairs of speakers at that time.

The tweeters do protrude out the front. My answer was to add spacers behind the grilles so they cleared the drivers.

-Ed


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 Post subject: Re: Realistic Optimus 1 Speakers--Crossed Over So Low ?
PostPosted: May Wed 20, 2015 4:31 am 
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Great find!

When I got out of the service in 1971, my mother graciously co-signed a loan for me so that I could purchase an Allied 395 receiver, an Elac-Miracord turntable, and a set of Optimus speakers. All from Radio Shack. Pioneer made the Allied 395, not sure who made the speakers. Yes, they really had some good stuff back in 70s. The quality of my system, back in those days, rivaled some of my friend's much more expensive and "exclusive" systems.

I foolishly let the system slip away from me in 1987. As luck would have it, I came across an Allied 395 in near mint condition last year. Now, if I could only find a duplicate turntable and speakers (I am looking)!

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 Post subject: Re: Realistic Optimus 1 Speakers--Crossed Over So Low ?
PostPosted: May Wed 20, 2015 8:20 pm 
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i just fired up the optimus 5 speakers today.

i thought the opt 1 speakers were fantastic, but these are even better.

again, they are very smooth and un tiring on the ears for a clean bass and silky smooth highs. the bass does not whomp. it is clean.

i could listen to them all day and the ears will not tire.

http://www.canuckaudiomart.com/details/ ... es/501134/

steve

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 Post subject: Re: Realistic Optimus 1 and Opt. 5 Speakers--Great Finds
PostPosted: May Thu 21, 2015 8:15 pm 
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I worked at Radio Shack for a while in the 70s. Interesting (at least to me) point about their speakers: once or twice a year, they would have a 50% off sale. It was a big deal, and a lot of people poured in to buy them. What the public didn't know was this: at 50% off, the dealer or store was still guaranteed a gross profit of 40%. So you can see what type of mark-up there was to begin with.

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 Post subject: Re: Realistic Optimus 1 and Opt. 5 Speakers--Great Finds
PostPosted: May Thu 21, 2015 8:26 pm 
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i remember that. that's how i bought all my machs when i was a teenager.

i also remember the Nova 6 speakers stacked in a pyramid in the front of the store. they were 29.99 back in the late 70's. i got two of them as well.

nearly every other month, they had some speaker on sale.

steve

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 Post subject: Re: Realistic Optimus 1 and Opt. 5 Speakers--Great Finds
PostPosted: May Sat 23, 2015 7:25 pm 
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In those years, I rolled my own. I used a number of Radio Shack drivers, but usually I bought from McGee Radio as they had a huge selection at good prices. The last one I built had a 15" and a 12" woofer in a 7 cu.ft. box with a separate attached sealed enclosure for five 4" mids and three tweeters. A little overkill, but man they sounded great on 100 wpc.

For the Nova7B, I just swapped out the two original tweeters for a dome and a mid. Too bad the center got pushed in on one of the tweets and a little trail of sticky residue might be the ferro-fluid leaking out. Or just a bit sloppy in the assembly of it. In the pics I show the spacers I added to the back of the grille to allow clearance for the dome tweeter.

-Ed


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 Post subject: Re: Realistic Optimus 1 and Opt. 5 Speakers--Great Finds
PostPosted: May Sat 23, 2015 7:51 pm 
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ed, pm sent, thanks.

it is a beautiful day outside and i'm putting a coat of satin varnish on the cabs. they are nearly dry and look perfect. the wood took a good "early american" minwax stain and the original color was well restored.

these were stored somewhere climate controlled but the wood was still dry. they soaked up the stain and varnish quite well.

now, i'm working on the big 4 way optimus 5 speakers. i'll post some pics of those sometime. they are all apart now awaiting capacitors while the cabs are getting the works of beauty.

steve

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 Post subject: Re: Realistic Optimus 1 and Opt. 5 Speakers--Great Finds
PostPosted: Nov Mon 12, 2018 12:17 am 
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I just saw a pair of these (Optimus 1) at a vintage hi fi shop. They were in excellent condition but the seller wanted more than $200 for them, which seemed kind of high to me. They were obviously made to compete with the KLH Model 6. They are similar in size and appearance. I think they sold for $79 vs $134 for the 6s. I have not heard them myself but from what I have read, they were not terrible speakers. Nonethless, if I were back in the day, I would have saved up the extra money for the 6s.


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 Post subject: Re: Realistic Optimus 1 and Opt. 5 Speakers--Great Finds
PostPosted: Nov Mon 12, 2018 3:20 am 
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realistic and optimus (radio shack) speakers were quite the sleepers.

they sounded fantastic.

pictured above, those infamous ring tweeters (with the cup) in those series of speakers were the smoothest, warmest, and "so easy on the ear" tweeters that i've ever heard. they were not harsh or tiring. they sounded like smooth silk when crossed over properly.

actually, they are my favorite tweeter and i've heard quite my share of vintage speakers over the years.

despite all this though, the seller is about $100-$125 too high on the price.

steve

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