Realistic Nova 8b Rebuild & Crossover Re-Design
- Thread starter videolady201
- Start date
DON_Chap
New Member
I am just starting to rebuild my NOVA 8s. Someone had previously replaced drivers with the wrong ones, 16 Ohm tweeters and one tweeter in series with a mid. They sounded like crap.
I sourced replacement tweeters from Parts Express: Phenolic Ring Tweeter. Recommended by some folks here on AK.
I purchased 4 new Midrange drivers from Simply Speakers, 4 Ohm: Midrange
I kept the stock woofer and I built the VL Mod crossover.
The stock isolation cone fits the new tweeter with a slight mod for the connection terminals. The mids are much larger than the stock drivers with bigger magnets, they really look like a step up over stock with greater power handling capacity.
I want to maintain sound pressure isolation so I designed and 3D printer speaker cups for them to sit in. I will have to modify the openings in the wood to fit them, some may say sacreligious, but I will never sell these so not an issue for me.
I will post photos later today as I start the modifications and assembly. Time will tell how they sound.
I sourced replacement tweeters from Parts Express: Phenolic Ring Tweeter. Recommended by some folks here on AK.
I purchased 4 new Midrange drivers from Simply Speakers, 4 Ohm: Midrange
I kept the stock woofer and I built the VL Mod crossover.
The stock isolation cone fits the new tweeter with a slight mod for the connection terminals. The mids are much larger than the stock drivers with bigger magnets, they really look like a step up over stock with greater power handling capacity.
I want to maintain sound pressure isolation so I designed and 3D printer speaker cups for them to sit in. I will have to modify the openings in the wood to fit them, some may say sacreligious, but I will never sell these so not an issue for me.
I will post photos later today as I start the modifications and assembly. Time will tell how they sound.
Lavane
Lunatic Member
I did a similar VL type mod on a pair of Nova 7B's another AK'r had done to his pair. It woke them right up.
I replaced the stock electrolytic crossover cap with a polypropylene film cap, used an inductor coil to force the woofer to roll of where it should instead of it running full range like it was, and reversed the phase of the two tweeters along with adding a bypass cap across the woofer. The mods can be easily reversed by bypassing the added coil, clipping out the bypass cap, and swapping the tweeter wires back to being in phase with the woofer.
They sound a lot better now. I also made new grills. I've never been a fan of lattice grills myself.
I replaced the stock electrolytic crossover cap with a polypropylene film cap, used an inductor coil to force the woofer to roll of where it should instead of it running full range like it was, and reversed the phase of the two tweeters along with adding a bypass cap across the woofer. The mods can be easily reversed by bypassing the added coil, clipping out the bypass cap, and swapping the tweeter wires back to being in phase with the woofer.
They sound a lot better now. I also made new grills. I've never been a fan of lattice grills myself.
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DON_Chap
New Member
Did you hold the new grills on with velcro? I was thinking about ditching the lattice. I have new cloth, or JBL foam might be kind of cool.
Lavane
Lunatic Member
No, the grill kits I used have pegs. I had to drill holes in the cabinets to put the rubber cups in that hols the pegs.
I've used those grill kits on two other sets of speakers. I pair of Marantz Imperial 6's and Polk Monitor 7's. Both of those pairs came to me without grills. The grill kits and cloth can be found at Parts Express. One grill kit with buying the extra set of corners and cross brace pieces is enough to do two speakers usually. The Imperials are just about the same size as the Nova 8's.
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DON_Chap
New Member
That is a nice clean look. Heading to Parts Express website now. I looked, and it looks good but I don't have another $60 to put into these so I will re-cloth the lattice grills as I have the cloth already.
Retired on a fixed income limits funds for toys.
Thanks!
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Lavane
Lunatic Member
It was kind of more than I wanted to spend on the Nova's. I saw a post where someone replaced the tired dark brown speaker cloth behind the lattice with a nice dark red cloth. It looked really nice. The plastic lattice pieces do unscrew from the grill baffle with the cloth on it.
It would be be a lot cheaper to replace the old cloth than make new grills.
It was worth it to me for the Imperial 6's and Polk Monitor 7's though.
Both pairs sound really good and are keepers for sure. I acually had enough rail pieces left over for the Nova's. I just had to buy new corner and cross brace pieces.
DON_Chap
New Member
That is the route I am taking. I have black cloth from Parts Express and I have them completely taken apart. I sanded the one speaker today and gave it a treatment of Bush Finishing oil. I'll sand and finish the second one tomorrow and while that is drying replace the cloth on both grills, clean the lattice up really good and then start reassembly. I'll have them all done by Friday - then I will see how they sound.
If I like them, I will have 3, 16 Ohm Tweeters and 4, 4 Ohm midranges to sell on FleaBay.
If I like them, I will have 3, 16 Ohm Tweeters and 4, 4 Ohm midranges to sell on FleaBay.
DON_Chap
New Member
I was thinking JBL foam would be cool too but for now I reassembled the lattice grills with new black speaker cloth.
DON_Chap
New Member
Finished the speakers yesterday and they sound great, although I have nothing to compare them too, only what they used to sound like. I am happy with them and the bl;ack grill cloth made them look much nicer, even with the lattice.
I sanded and refinished the walnut veneer, eliminated the plastic plate that had the old terminals and crossover and replaced that with a wood plate and spring terminals.
Next project is a restoration of a set of Optimus 1Bs and an STA-64 as a Christmas present for my daughter. The 1Bs sound great - they just need cosmetic refinishing.
I sanded and refinished the walnut veneer, eliminated the plastic plate that had the old terminals and crossover and replaced that with a wood plate and spring terminals.
Next project is a restoration of a set of Optimus 1Bs and an STA-64 as a Christmas present for my daughter. The 1Bs sound great - they just need cosmetic refinishing.
DON_Chap
New Member
Lavane
Lunatic Member
The Nova 7B's I have are the same as the Optimus 1B's other than cosmetics. I had a pair of 1B's years ago. I still have a pair of the smaller Optimus 2B's that are the same as the Nova 6's. They sound pretty good too.
Moondog55Two
New Member
Has anybody done a sweep of the woofer and have a graph of the response?
I've just taken the woofer out of the box and checked the factory XO and it it looks like the woofer runs straight with no XO elements at all and if I go ahead with this rebuild I'd like to cross to the midrange a lot lower than 1700Hz
I was never going to use the factory mid & tweeter drivers and I sold them last year. it's just taken me a while to get myself organised
I've just taken the woofer out of the box and checked the factory XO and it it looks like the woofer runs straight with no XO elements at all and if I go ahead with this rebuild I'd like to cross to the midrange a lot lower than 1700Hz
I was never going to use the factory mid & tweeter drivers and I sold them last year. it's just taken me a while to get myself organised
Moondog55Two
New Member
Also if anybody wants a set of the original crossovers I'm happy to sell these cheap as I won't be using them now
Lavane
Lunatic Member
A lot of Realistic speakers just have the woofers running full range, no inductor coil.
One of the speaker designers for Rado Shack was here on AK a few years ago. He explained they had the woofers made to roll off where they wanted them to. So no coil needed. I thought it made a difference for the better adding a coil to the 7B's to force the woofer to roll off. I added crossovers with a coil, and a dome tweeters to a pair of Nova 4's too. The new crossovers crossed over at the same frequency as the original cap RS used as the only crossover componant. They sounded much better also.
maxhifi
Addicted Member
Do you remember what thread he posted to? I must have missed that one. That's pretty cool how AK has such a broad reach.
Lavane
Lunatic Member
It was several years ago. It may have been lost when the server had problems back then. The person made some posts in a thread concerning Realistic speakers. He left RS in the early 90's if I remember right. It seemed like he wasnt happy with the direction of the company.
I looked for that thread before myself without any luck sorry.
Gnesen
Super Member
Here you go:
A lead Designer from Tandy -
If you look at my post in "Vintage Radio Shack/Realistic Speakers?" you will see my reply to Tecexec. He wrote me an email that I would like to share. He encouraged me to do so, thank you. I can't wait to show my friend of over 30 years who lived by me. He had those T-70s and to this day we...
audiokarma.org
Lavane
Lunatic Member
There is another thread too. This isn't the one I was thinking of or seen before. Thanks for posting it.
Gnesen
Super Member
Ah, okay. I wonder if the thread you're thinking of is from/about the same person. Here's a link to a list of all of Tecexec's posts.