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Realistic Nova 8b Rebuild & Crossover Re-Design

I picked up some an 8b pair a couple of months ago. When I got them, they sounded like crap. A few replacement parts and a re-cap later, they did sound better, but not good enough. After a little fiddling, I decided to make an l-pad out using the stock resistors in series and adding a 15Ω across the mid speakers and a 10Ω across the tweeter to stabilize the impedance and crossover points. It really helped a lot. The biggest impact is the difference in the mid and high switches. Low-Normal-High makes a much bigger difference now. They are now my neutral/easy speakers to listen to for the kind of music that requires it.

Oh… I forgot to mention that even after that, I decided to add a period-correct tweeter instead of the paper cone stock one. That helped a TON!
 

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Nice. I often warn people give your ears time to adjust. It's quite incredible what happens when we give things sufficient time so our ears have time to adjust. Glad you are enjoying them. I have 5b and 8b speakers and yet to do the VL upgrades. But soon, now that I'm retired.
 
GonzoF1 said:
I picked up some an 8b pair a couple of months ago. When I got them, they sounded like crap. A few replacement parts and a re-cap later, they did sound better, but not good enough. After a little fiddling, I decided to make an l-pad out using the stock resistors in series and adding a 15Ω across the mid speakers and a 10Ω across the tweeter to stabilize the impedance and crossover points. It really helped a lot. The biggest impact is the difference in the mid and high switches. Low-Normal-High makes a much bigger difference now. They are now my neutral/easy speakers to listen to for the kind of music that requires it.

Oh… I forgot to mention that even after that, I decided to add a period-correct tweeter instead of the paper cone stock one. That helped a TON!
Click to expand...
That tweeter looks suspiciously like the common silk dome made by Peerless, they were super popular in the late 70s through the 90s, even used in car installs, I still have a set of small frame Orion XTRs with the metal cased crossovers. The frames always dried out and the weight of the magnets would cause the clips or tabs to break off. I had an extra set of diaphragms for the small size, haven't seen them in a while. They're one of those things that you constantly come across (in their little Styrofoam boxes) but then when you need them you can't find them.

I think they were $8 each in the 90s. Problem was, the mounting part was never available and always broke when changing the diaphragms. The big ones can handle some watts, they were even faster to break with the larger magnets, car audio used to be a real challenge back in the day before neodymium magnets. Install used to be a real craft in the 90s, nothing was standardized or made to fit, a sheet metal snips and a sawzall were basic tools of the trade with a 9v Makita screw gun.

Radioshack made their own version that they used in those little metal cabinet speakers (the minimus? 7?) I still have a set of the bigger white ones (pro?8?). They used metal frames that would crush the coils if you weren't careful putting them back together, the magnets were super strong, the tweeters were as big as the woofers.
 
A good bit off-thread now.
I've been wondering for a couple of years now about cutting out the top part of the baffle and while keeping the bass driver replace the original mids and tweeter with more modern drivers. Is there a thread anywhere with people doing this?
I've been unable to find the smaller brother of the 8Bs which was always my plan
 
Moondog55Two said:
A good bit off-thread now.
I've been wondering for a couple of years now about cutting out the top part of the baffle and while keeping the bass driver replace the original mids and tweeter with more modern drivers. Is there a thread anywhere with people doing this?
I've been unable to find the smaller brother of the 8Bs which was always my plan
Click to expand...

The Optimus 25 might be a better starting point if that's the intention.
 
Moondog55Two said:
A good bit off-thread now.
I've been wondering for a couple of years now about cutting out the top part of the baffle and while keeping the bass driver replace the original mids and tweeter with more modern drivers. Is there a thread anywhere with people doing this?
I've been unable to find the smaller brother of the 8Bs which was always my plan
Click to expand...
A lot of people replace the cone Tweeters with domes with the same diameters it's important that you check the impedances and match them if possible. I did it with great success also used polypropylene caps in the crossovers . I think I lowered the point by increasing their values a bit .
 
Moondog55Two said:
I don't recall those ever being sold in Australia and aren't they only a 10" woofer?
I was looking for the 7B because the integration of a 10" to a midrange is a lot easier than with a 12"
Click to expand...

Yes it's a 10". Don't know about Australia. I didn't know you had Radio Shack down there! Here in Canada we also didn't get all of the exact same models as the US got.

I had a pair of the 25s for a while last year, and enjoyed their sound. Having a real midrange was a big help versus the Nova 7B.
 
The tweeter in the 8B's arw supposed to be better than the 7B's. But a nice soft dome would probably sound better. I dunno if I would mess with the midrange though.
 
Lavane said:
The tweeter in the 8B's arw supposed to be better than the 7B's. But a nice soft dome would probably sound better. I dunno if I would mess with the midrange though.
Click to expand...
Would be fun to try a soft dome that jived with the x-over etc.. Hell if you can find one that can be added, look OEM and not ruin cabinet it could really transform these speakers.
 
QUiKSR20 said:
Would be fun to try a soft dome that jived with the x-over etc.. Hell if you can find one that can be added, look OEM and not ruin cabinet it could really transform these speaker.
Click to expand...
These should work. They're actually a dual ring radiator.
I paln on trying them in a pair of Marantz Imperial 6 speakers.
I'm also thinking of trying them in the Nova 7B's I have also.

hifihaven.org

DIY - Original Large Advent (OLA) - Tweeter Upgrade

The factory tweeter, although unique in its time, leaves a bit to be desired. I actually think it sounds good but was curious when I was perusing Parts Express and I came across this Peerless tweeter. This Peerless tweeter is a perfect upgrade for the original orange or green ring radiator...
hifihaven.org hifihaven.org
 
Hey all, I am working on completing the VL mod on a pair of mach ones. The superglue on the cone seemed to do a great deal to tighten up the bass there. Has anyone tried this on 5bs? Worth a try? Is there a reason not to?
 
vinylocerous said:
Hey all, I am working on completing the VL mod on a pair of mach ones. The superglue on the cone seemed to do a great deal to tighten up the bass there. Has anyone tried this on 5bs? Worth a try? Is there a reason not to?
Click to expand...
I would NOT. Different cone material. If VL thought it would be a good idea it would have been in the upgrade instructions.
 
vinylocerous said:
Hey all, I am working on completing the VL mod on a pair of mach ones. The superglue on the cone seemed to do a great deal to tighten up the bass there. Has anyone tried this on 5bs? Worth a try? Is there a reason not to?
Click to expand...
As for the VL mod on a pair of 5B's, as long as its the same used for the Nova 8B's, then yes it's doable. The Nova 8B and Optimus 5B arw the same speaker.
The only difference is in cosmetics. The 7B's have lattice grills with a beveled edge on the front of the cabinet. The 5B's just have grill clothes with a raised rectangular strip around the front edge of the cabinet. I have a pair of Nova 7B's that I added a coil to the woofers to force them to better roll off where thwy should. The bass is tighter and better controled now. I also made new grills for them. I've never cared for lattice grills personally.
 

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Lavane said:
As for the VL mod on a pair of 5B's, as long as its the same used for the Nova 8B's, then yes it's doable. The Nova 8B and Optimus 5B arw the same speaker.
The only difference is in cosmetics. The 7B's have lattice grills with a beveled edge on the front of the cabinet. The 5B's just have grill clothes with a raised rectangular strip around the front edge of the cabinet. I have a pair of Nova 7B's that I added a coil to the woofers to force them to better roll off where thwy should. The bass is tighter and better controled now. I also made new grills for them. I've never cared for lattice grills personally.
Click to expand...
I miss my 7B speakers. Had two sets. I contemplated updating the x-overs. Do you recall the value of the coil?
 
Copa1934 said:
I miss my 7B speakers. Had two sets. I contemplated updating the x-overs. Do you recall the value of the coil?
Click to expand...
Yes, 1mh. I had originally had also added a bypass cqp across the woofer as well. But that was a mistake though. It wasn't a good idea with this type of crossover so I removed it. I also replaced the electrolytic cap with a polypropylene film cap. The nice thing about adding the coil is its easy to just remove it. I liked the end results with the coil added though.
My only complaint about these speakers is the midrange/tweeters are laser focused. There's a very narrow sweet spot when listening to them. I've been meaning to experiment with pieces of felt around them.
Below is a picture of the crossovers with new caps and the coils. The bypass caps are sill attached across the woofers in the picture though.
 

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