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Realistic Optimus-1 (KLH-6 copy)

These are for the Optimus 5's I believe. I got them from Ed over on the Yahoo Realistic group.

Vas: 4.5848
Qms: 4.8624
Qes: 0.6577
Re: 7.0658 ohms

No Fs or Qts though, dunno why.
 
HTHMAN said:
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.
Click to expand...

For clarification, I just measured each and the 17 has a 10 inch woofer and the 6 has an 11 inch one. Definitely not the same woofer.

dew.
 
Here's the full skinny, unedited:

Just finished testing a coupl more woofers, and thought I'd share
the
> findings:
>
> Optimus-5B/Nova-8B 12" Woofer
>
> Better than I thought it would be. This woofer, like it seems all
> Realistic speakers, was designed for max whomp with a Qtc of 1.15-
1.2
> in in the Opti-5B enclosure. The F3 is 36-37 Hz, only ever so
slightly
> better than than the 10" Opti-1, which achieves an F3 of around 38
Hz,
> but not close to the claimed 20 Hz. It is best suited for sealed
> enclosures, so I wouldn't try porting this box. It would seem that
as
> with the Opti-1 vs. 1B, the newer B version of the 1 and 5 are
indeed
> improvements, even though they utilize slightly smaller cabinets.
>
> Optimus-2B/Nova-6 8" Woofer
>
> Same as above, maxed out Qtc of 1.2, F3 47-48 Hz. Not suitable for a
> ported enclosure. If you plan on upgrading the tweeter and leaving
the
> stock woofer in place, you *must*:
>
> a.) Replace the crossover or kiss your new tweeters goodbye. A
Dayton
> 12 dB crossover at 2000 Hz works beautifully, and
>
> b.) Add a Zobel circuit to flatten out the impedance. The impedance
> begins to climb with all of these Realistic woofers around 400 Hz,
> because that's about where they were crossing over to the cone
> tweeter. The correct values to use for the Opti-2B are 16.04
> microfarads cap, 9.5 ohm resistor. Solder the cap & resistor
together,
> and bridge them between the positive and negative connections on the
> woofer.
>
> If you'd like to try adding a Zobel circuit to your existing
Realistic
> woofer, here are some values:
>
> Opti-5B/Nova-8B: 32 uf cap, 8.83 ohm resistor
> Opti-1/Nova-7: 12 uf cap, 8.21 ohm resistor
> Opti-1B/Nova-7B: 31 uf cap, 9 ohm resistor

Again, just reposting what I got over there in response to my investigation back when I was working with these woofers.
 
Thanks Speedle. Thanks for sharing.

I guess I need to check into joining over at Realistic Group too.
 
I have a lead on these speakers on my local Craig's list for $30 - original owner and claims they are in perfect condition - would $30 be a fair price for a pair of these.

Ironically there is also a pair of these listed one line below these for these - also $30for the pair - and nope, it's not the same seller from what I can tell.

REALISTIC NOVA 15 SPEAKERS
 
proimage1 said:
I have a lead on these speakers on my local Craig's list for $30 - original owner and claims they are in perfect condition - would $30 be a fair price for a pair of these.

Ironically there is also a pair of these listed one line below these for these - also $30for the pair - and nope, it's not the same seller from what I can tell.

REALISTIC NOVA 15 SPEAKERS
Click to expand...

I would take the Optimus 1's. They are very good speakers-I have 2 pair. I would pass on the Nova 15's. I have a pair of Nova 5's that are probably the same drivers in a little different box. They just are not in the same league as the Optimus 1's. Much too boomy for my taste, but I got them for free because they needed foam. They are worth a generic refoam but not much more.
 
HTHMAN said:
I would take the Optimus 1's. They are very good speakers-I have 2 pair. I would pass on the Nova 15's. I have a pair of Nova 5's that are probably the same drivers in a little different box. They just are not in the same league as the Optimus 1's. Much too boomy for my taste, but I got them for free because they needed foam. They are worth a generic refoam but not much more.
Click to expand...

Then the 1's I'll get - seemed like a good deal if they're in as good a condition as he says they are -- hopefully sometime this week I can run over and check them out - about 45 minutes from where I live -- they might be gone, but I'll know soon enough. Really, the last thing I need right now are MORE speakers OR anything else to - but we all know how we are ! :banana:

Thanks for the advice ! Appreciate it !
 
Thank you speedle for the post about the zobel circuit. I just bought a pair of Optimus-1 speakers and realized the high freq was bleeding through the woofer when at high volume after reading your post. To balance out the impedance I put together the zobel circuit then hooked it up using alligator clips and tested it. The low frequency is a lot cleaner and less distorted than when bypassing the circuit. Your friend really knows his stuff. Cheers to him.

Here are a few images for those interested
http://i44.tinypic.com/okoowj.jpg
http://i39.tinypic.com/29ymu1k.jpg
 
Last edited:
Quick question: I picked up a pair of Optimus-1 speakers today, and I don't see how the cloth grill is removed. There isn't any gap between the cabinet and the grill - I tried to wedge a butter knife in, and it wouldn't fit. How is the cloth grill removed from the front?

Thanks
 
n.phelge said:
Quick question: I picked up a pair of Optimus-1 speakers today, and I don't see how the cloth grill is removed. There isn't any gap between the cabinet and the grill - I tried to wedge a butter knife in, and it wouldn't fit. How is the cloth grill removed from the front?

Thanks
Click to expand...

There is a strip of Velcro at each corner. You need to pry a corner out and the rest will follow. Try a putty knife or a stiff wire bent at 90 degrees at the end to get behind it. Every time I take mine off, I say that I need to put a pull tab on it, but never do it.

Hooked one of my pair to my Realistic STA-2000 a couple days ago. Great match for each other.
 
HTHMAN said:
There is a strip of Velcro at each corner. You need to pry a corner out and the rest will follow. Try a putty knife or a stiff wire bent at 90 degrees at the end to get behind it. Every time I take mine off, I say that I need to put a pull tab on it, but never do it.
Click to expand...

Thanks a lot. It took a while, but I was finally able to get them off, and then I stapled a short piece of ribbon to the back of the grill cover to help in the future. Now I just need to clean them up and try to restore the finish a bit.
 
HTHMAN said:
There is a strip of Velcro at each corner. You need to pry a corner out and the rest will follow. Try a putty knife or a stiff wire bent at 90 degrees at the end to get behind it. Every time I take mine off, I say that I need to put a pull tab on it, but never do it.

Hooked one of my pair to my Realistic STA-2000 a couple days ago. Great match for each other.
Click to expand...
Another option is a paint can opener. I've been using one for years now for MANY speaker, shall I say, challenges. Prying up drivers, taking off stubborn grills, etc.
 
Copa1934 said:
Another option is a paint can opener. I've been using one for years now for MANY speaker, shall I say, challenges. Prying up drivers, taking off stubborn grills, etc.
Click to expand...

That was exactly what I used, but with the addition these tiny strips of ribbon, I won't have to worry about scratching up the frame.
 
n.phelge said:
That was exactly what I used, but with the addition these tiny strips of ribbon, I won't have to worry about scratching up the frame.
Click to expand...
Yeah, definitely like the idea of the ribbons. Or something, anyway, to make removal easier. Just messing with my 5b speakers yesterday. Not too bad, but still would be a lot easier with something to pull on.
 
HTHMAN said:
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
Click to expand...

the edge to edge diameter of the actual cone...the black part for KLH model 6 is 7 inches. The 12" rating is based on the distance between opposing mounting screw holes. The distance across the cone is what matters. The KLH model 6 and AR2series have the same effective size cone even though the AR2 series is rated at 10". This may be a KLH woofer but maybe not. It has the same orange concave outer suspension many variants of the KLH model 6 speaker had but there's no way to tell if it really is one. The tweeter does not look like a KLH tweeter. My hunch is that they are not the same.
 
Those are serious cabs! With the exception of a couple 15" driven speakers, early RS speakers had good size cabinets, probably much better matched to the drivers installed. Mach speakers are notorious for having too small a cabinet.

They sure look nice. Deep buggers, like my HPM speakers. They aren't very wide, but boy they are deep.
 
Soundminded said:
the edge to edge diameter of the actual cone...the black part for KLH model 6 is 7 inches. The 12" rating is based on the distance between opposing mounting screw holes. The distance across the cone is what matters. The KLH model 6 and AR2series have the same effective size cone even though the AR2 series is rated at 10". This may be a KLH woofer but maybe not. It has the same orange concave outer suspension many variants of the KLH model 6 speaker had but there's no way to tell if it really is one. The tweeter does not look like a KLH tweeter. My hunch is that they are not the same.
Click to expand...

Those are not KLH six woofers. Just a copy. KLH baskets don't protrude out, the dust caps are much smaller, the cone material is not smooth but textured. The cloth surrounds are actually white, the sealer is black on model sixes except for the early epoxied woofers, which are similar to the Optimus surrounds, and used a clear surround sealer. I have both versions of the model six. I also believe the six and model five and twenty three woofers are the same size, but the five and twenty there's magnet is larger. The six woofer is unique to that speaker. KLH advertised them as a 12 inch woofer, the model 17's as a 10 inch woofer.
 
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