Realistic Nova 7B Crossover

DTiberius

Member
Hello!
Does anyone know what the crossover frequency is for the Nova 7B? I've tried searching everywhere with no luck! The Crossover is for the tweeter only and is a 2nd order. the cap is a 15mf and the coil is a 1.0 mh.
Thanks!
 
Hello Celt! Thanks for responding! The Nova 7b's are a weird setup, they have two 16 ohm tweeters wired in parallel to get 8 ohms. I've tried using my calculator (8 ohms), but my numbers don't add up... Any thoughts?
 
Yeah, that's what I thought! But I can't find any specs on these speakers online! Thanks for your help, Celt!
 
Lets not forget, their tweeters aren't exactly the delicate tweeters of today. Also, I've seen these cabs with dead tweeters, so maybe radio shack was too aggressive with their crossover point, choosing something too low for them at higher volumes. I bet they chose 1000 hertz, especially being a second order crossover.
 
The crossover point very well could be 1000. This isn't uncommon for realistic speakers, and the tweeters they made were designed to go low - sort of like a full range mid/tweeter. I really like the 7B's, mine are currently at me Dad's paired with a STA-84 receiver - quite a nice combination.
 
I actually got these a week ago from a friend that was gonna toss 'em! They belonged to his Dad and had been sitting in a closet for 25 years! They are in very good shape and from what I can tell the grills had never been removed! All the tweeters still work! I have them hooked up to a STA-2000D and they sound great, the bass is incredible!!!
I have done VL's mods to my Mach ones and loved how those turned out. I want to play around with the crossover on these to see if I could make them sound any better, since I have to change the caps anyway. Any ideas?
 
Yes the bass on these is very impressive. I was a bit stunned by it when I first heard them. I just replaced the one cap in the crossover and liked what I heard. I think I remember VL saying a crossover mod was in the works for the 7B but it never materialized.
 
I've had a few Optimus speakers of this vintage, and yes, the bass is very nice... like an improved version of the vintage KLH bass sound! If you want to horrid them, but keep them true to their original sound, try putting second order crossovers on the tweeters and woofer, and reverse the polarity on the tweeters in respect to the woofers. That would be my thoughts.
 
The crossover point very well could be 1000. This isn't uncommon for realistic speakers, and the tweeters they made were designed to go low - sort of like a full range mid/tweeter.

The 1975 Radio Shack catalog (page 25) calls them "midrange/tweeters" for both NOVA-7B and Optimus-1B, which share the same drivers.

Those 16 ohm "tweeters" (0705Ae) are rated for 350Hz to 18kHz according to the label on early examples that includes more text:
Both wide range "tweeters" are identical 16 Ohm 0705Ae.

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As suggested, crossing over the woofer might be worth exploring. The original NOVA-7 uses a crossover on the woofer. Radio Shack chose to let the 7B woofer run free, which may have just been a cost-cutting measure.
 
Wow! Stuart! Thanks for the info! Tweeters that go down to 350hz?! My tweets have the same model number but it's stamped on the magnet. I don't have the label. Realistic crossing the tweets over at 1000hz makes a little more sense now. You wouldn't happen to have that same label on the woofer, too?! It would be great to know what the upper end limit is on the woofer! I'd like to try to put a 2nd order crossover in these babies!
 
Wow! Stuart! Thanks for the info! Tweeters that go down to 350hz?! My tweets have the same model number but it's stamped on the magnet. I don't have the label. Realistic crossing the tweets over at 1000hz makes a little more sense now. You wouldn't happen to have that same label on the woofer, too?! It would be great to know what the upper end limit is on the woofer! I'd like to try to put a 2nd order crossover in these babies!
I have two pair of the 7b speakers and really enjoy them. One pair is setup here at my business in my workshop, so I listen to them roughly 5-7hrs a day. No fatigue, impressive bass for such a small speaker.

As to the comment earlier about running the woofer "free", that was typical of vintage JBL as well, my L88 and L88nova both ran free, as did a number of other JBL speakers. I'm sure there were many other makes and models as well, so probably nothing to do with cost cutting. They probably believed that was the best way to do it back then.
 
...As to the comment earlier about running the woofer "free", that was typical of vintage JBL as well, my L88 and L88nova both ran free, as did a number of other JBL speakers. I'm sure there were many other makes and models as well, so probably nothing to do with cost cutting. They probably believed that was the best way to do it back then.

I've run across tons of vintage cabs that had a cap on the tweeter and nothing on the woofer. This was definitely a common practice back then.
 
I've run across tons of vintage cabs that had a cap on the tweeter and nothing on the woofer. This was definitely a common practice back then.
I don't think until manufacturers benefited from T/S specs and proper software and equipment that they could build the types of networks we see today. I'm sure many would shake their heads, but then realize that had they had the same information AND tools at their disposal, they may have engineered speakers differently, even 40 years ago.
 
You wouldn't happen to have that same label on the woofer, too?!

Here ya go:

7B woofer.JPG

I wouldn't read these specs as meaning "flat" response (i.e., +/- 3dB) throughout the stated range. But one might expect a happy frequency response within perhaps an octave of each end.

If memory serves, VideoLady's measurement of NOVA-8B's 12" woofer showed very good performance to about 1600Hz. That suggests 7B's 10" version could have useable extension at least as far on the high end.
 
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Copa,
I had a pair of 4024A's! I sold them last year and I was so bummed out about it my daughters tried to replace them! But, they're 4029's... (Bless my girls for trying, though!) However, with a refoam and VL's mods, they sound pretty sweet!
 
I finally picked mine up this weekend after purchasing on Ebay 9 months ago, had a college room mate go pick them up and hold them.

Any progress on the x-over mods?
 
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