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Realistic Optimus 5/Nova 8 Tweeter options use w/ OOTB crossover

J

joebor1776

Member
Hi,
May I please get your opinions for tweeters, for restoring some Realistic Optimus 5's? I bought a hacked-up set with great cabinets for $40. But one woofer had been replaced with a home theater woofer (!) and the other one is the original 3007Aa woofer but has been re-coned. I've purchased a replacement 3007Aa and will eventually replace the re-coned one. All midrange tweeters are there and intact, but one tweeter was replaced with a 4-ohm computer speaker tweeter and the other is an 8-ohm Realistic tweeter with a mystery part number 0725Ab. I *think* this might be from an Optimus 5b/Nova 8b, but not sure--I thought those were 0725Ac part numbers.

I've read almost the entire 59 pages of the VideoLady crossover mod thread, and while it sounds really interesting, I don't want to spend anymore $ on these for a difference that I may not be able to detect. So I'm going to replace the caps and keep the standard Optimus 5 crossover spec. However, I have had trouble finding the correct 0705Ac 4 ohm tweeters, and haven't been able to find a modern replacement that's 4 ohms (at least not one that seems like it would go low enough).

My question is, what should I do? Hold out for 2 working 0705Ac original tweeters? Or does anyone know of a modern replacement that is 4 ohms that would work? Or, should I buy 1 more 8 ohm tweeter from an Optimus 5b/Nova 8b--and if so, would using the 8 ohm tweeters change affect the crossover much?

Thanks, sorry for the long-winded paragraphs.
-Joel

Pics if you're curious
Mystery tweeter (from a 5b/8b?)
IMG_20180211_210416258.jpg

Reconed 3007Aa
IMG_20180211_211508941.jpg
 
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These speakers sound really nice with the original parts.
If you swap out for different parts, then you may really have to alter the crossovers as well to accommodate the different frequency response.
The crossover mod thread is interesting, but the parts are quite expensive.

Radio Shack sold lots of these speakers. The drivers should be available with some patience.
 
Thanks, that was what I was afraid of, wouldn't know where to start altering the crossover, and yea, that mod gets expensive (and looks like a fair bit of work). I'll be patient and keep looking for the 0705Ac tweeters. Thanks for the response!
 
These are a nice replacement for the paper cone tweeter.
I have them in a set of Nova 8Bs that I've had for 25+ years
40-1276B
s-l640.jpg
 
Thanks, I looked that up and it looks like those are 8 ohm? I think I'll need to stick with 4 ohm tweeters to be able to use the original crossover design for the Optimus 5. Maybe there's a 4 ohm version though.
 
Yep. My goof. Once I got Nova 8B in my head, all bets were off :)
But since I already pushed a silk dome on you, how about one in 4 Ohm?
https://www.parts-express.com/peerl...source=google&utm_medium=cpc&utm_campaign=pla

One thing though: I think t he Optimus 5 had a 4.7uF cap for the tweeter, which would put the crossover point at around 8KHz if it was a 4 Ohm tweeter. It would be closer to 4 KHz if it was an 8 Ohm tweeter.

264-1040_HR_0.jpg
 
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Thanks! I think I looked at that one, and wasn't sure if its resonant frequency of around 1100 Hz was low enough. I think I remember reading somewhere that the crossover was at 1000 Hz--but I've read so many threads on here over the past few days that I could have misread it :-). Anyway, I did find an original set of tweeters from a Nova 8 on the 'bay for $17, so I went ahead and ordered them--if they end up not working, I'll probably be back to looking for a modern replacement, possibly the one you recommended above. Thanks again!
 
soundguy9 said:
I am wondering, did you pick a tweeter? I am in the same situation today.
Click to expand...
https://www.parts-express.com/search?keywords=bc25tg15-04&oq=bc25tg
These Peerless silk dome tweeters work real well with very little modification.
03.JPG04.JPG

I used a Dremel to shave a little off the front baffle to get the tweeter to fit.
01.JPG

The Peerless tweeter is almost the same size bolt pattern , just a slight bit larger.
With the original tweeter out and the screws extended I pushed them outward , angled them some
When I mounted the new tweeter in I started with 2 opposite holes , then got the other 2 holes started
The tweeter ends up extended from the baffle when all 4 holes are started (the screws are plenty long enough) ,
then I just tightened the screws down evenly (criss-cross pattern like lug nuts on a tire) to bring the tweeter down
to the baffle.

02.JPG

I also made a gasket out of some foam-rubber sheet I got from the local craft store.

You don't need to use-reuse the plastic cup behind the original tweeter , these Peerless silk dome tweeters are sealed in back.

04.JPG
 
f0427ea said:
https://www.parts-express.com/search?keywords=bc25tg15-04&oq=bc25tg
These Peerless silk dome tweeters work real well with very little modification.
View attachment 3119446View attachment 3119447

I used a Dremel to shave a little off the front baffle to get the tweeter to fit.
View attachment 3119453

The Peerless tweeter is almost the same size bolt pattern , just a slight bit larger.
With the original tweeter out and the screws extended I pushed them outward , angled them some
When I mounted the new tweeter in I started with 2 opposite holes , then got the other 2 holes started
The tweeter ends up extended from the baffle when all 4 holes are started (the screws are plenty long enough) ,
then I just tightened the screws down evenly (criss-cross pattern like lug nuts on a tire) to bring the tweeter down
to the baffle.

View attachment 3119457

I also made a gasket out of some foam-rubber sheet I got from the local craft store.

You don't need to use-reuse the plastic cup behind the original tweeter , these Peerless silk dome tweeters are sealed in back.

View attachment 3119459
Click to expand...
Excellent work, thank you for sharing it. You must have also improved the sound at the same time.

Are those AR speakers on the left side?
 
soundguy9 said:
Excellent work, thank you for sharing it. You must have also improved the sound at the same time.

Are those AR speakers on the left side?
Click to expand...
These Peerless silk dome tweeters with their 93 dB sensitivity are a perfect match for Op'5 speakers , they sound real nice and smooth
and the price is real respectable for as nice as they sound ;)

For the hardened/stiff cloth woofer surrounds search out D.O.T. 3 brake fluid surround treatment, the surround dope/sealer used on these speakers responds real well to a brake fluid treatment, it'll soften them woofers right up.

The speakers on the left are Polk 7B monitors, another very nice sounding speaker.
 
thanks for all your comments, it is appreciated.

so I have picked up 2 pairs,

the 5s:
hooked up the speakers and gave them some time to get loose. The low end is good, tweeters are working but nothing to brag about them here. The mids are kind of lacking for me. I am going to give them more time and see what I need to improve on this set.
the new caps are on the way

the 5Bs:
some of the domes are lightly pushed in, will connect them to the amp tonight
need to place an order for new caps
 
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