• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Realistic Nova 8b Rebuild & Crossover Re-Design

videolady201 said:
Anyone got your Nova 8bs or Optimus 5bs modded with all stock drivers yet?
Click to expand...

I recently found a set of these for free and to be honest I think in their stock configuration they sound like ass- So, I wanted to see just how much difference this mod could make

I just completed the x-over per VL's instruction on one Optimus 5b speaker... So I've been doing a little left channel / right channel comparison.

There is a dramatic difference between the modded and stock speakers.
The modded speakers bass definitely reaches lower and much cleaner, it has a really nice punch that was missing from the stocker, I sealed around the bass driver with weatherstrip and resealed the cabs too, this may have helped a little with this as well.

The overall sound is much improved as well, however I'm a little disappointed with the highs... I was hoping for a bit more high end detail - I could have something wrong, but I traced each circuit numerous times and I believe I have it correct. (It was difficult cramming all the components onto the board...so it's no work of art for sure... but I checked it ten ways to Sunday)

It could be an issue of listening to only one channel at a time.... it's hard to get a good read, so I look forward to completing the second unit.


I measure 7.2 ohms for the completed unit and 7.4 on the stock speaker- is this correct?

Also are these designed for bookshelf use, on stands or right on the floor?
 
Nova 5b Mods

Buttercup said:
I recently found a set of these for free and to be honest I think in their stock configuration they sound like ass- So, I wanted to see just how much difference this mod could make

I just completed the x-over per VL's instruction on one Optimus 5b speaker... So I've been doing a little left channel / right channel comparison.

There is a dramatic difference between the modded and stock speakers.
The modded speakers bass definitely reaches lower and much cleaner, it has a really nice punch that was missing from the stocker, I sealed around the bass driver with weatherstrip and resealed the cabs too, this may have helped a little with this as well.

The overall sound is much improved as well, however I'm a little disappointed with the highs... I was hoping for a bit more high end detail - I could have something wrong, but I traced each circuit numerous times and I believe I have it correct. (It was difficult cramming all the components onto the board...so it's no work of art for sure... but I checked it ten ways to Sunday)

It could be an issue of listening to only one channel at a time.... it's hard to get a good read, so I look forward to completing the second unit.


I measure 7.2 ohms for the completed unit and 7.4 on the stock speaker- is this correct?

Also are these designed for bookshelf use, on stands or right on the floor?
Click to expand...

You will get the best response with them 8 to 10 inches off the floor! Also, the highs should be very smooth and extended, very strong and open. I would check the tweeter and make sure it is not half shorted. Out of the cabinet they should read right at 7 ohms, the mids in series should also read right at 7 ohms. Also, as close as you have to put the coils they will react with each other if they are not 90 degrees both directions to each other. Also, the mids and the tweeter should be wired out of phase, - to + and + to -, either at the crossover or at the speaker terminals.
 
You really did an outstanding job to those speakers. I'm very impressed with the crossover design.Just beautiful all around !
 
greenmark59 said:
I just found (haven't bought yet) a pair for $20 in the Cincinnati area. He listed them for $40 and didn't know what kind of speakers they were. After corresponding with him, we finally agreed they were Nova 8B's.

Would you be interested in buying them tmblack? I don't know where you are located.
Click to expand...

If the woofer in the 8b is the same as that in the 7b, I'd be open to buying one of the woofers. I missed out on one on ebay to replace the ghetto woofer in one of my 7bs. I'm so disappointed in myself.
 
videolady201 said:
You will get the best response with them 8 to 10 inches off the floor! Also, the highs should be very smooth and extended, very strong and open. I would check the tweeter and make sure it is not half shorted. Out of the cabinet they should read right at 7 ohms, the mids in series should also read right at 7 ohms. Also, as close as you have to put the coils they will react with each other if they are not 90 degrees both directions to each other. Also, the mids and the tweeter should be wired out of phase, - to + and + to -, either at the crossover or at the speaker terminals.
Click to expand...


I think I'll do the 2nd set using a different board where I can put more space between the coils and I'll orient them at 90 degrees from each other...
 
At this time I have the 2.7uf mounted atop the 2.0 bar core inductor with hot glue in between and the .35 is within 1/16" from the 2.0 as well...can I place something between the coils such as a credit card or piece of wood from a paint stir stick maybe to keep them from interfering with each other...
 
Coils

Buttercup said:
At this time I have the 2.7uf mounted atop the 2.0 bar core inductor with hot glue in between and the .35 is within 1/16" from the 2.0 as well...can I place something between the coils such as a credit card or piece of wood from a paint stir stick maybe to keep them from interfering with each other...
Click to expand...

None of that will work, the induction is magnetic. Did you check the ohms of your tweeters? Im interested to see what they read, I think that is where the main problem is. Also, did you wire them out of phase?
 
Woofers

tmccullough said:
If the woofer in the 8b is the same as that in the 7b, I'd be open to buying one of the woofers. I missed out on one on ebay to replace the ghetto woofer in one of my 7bs. I'm so disappointed in myself.
Click to expand...

They are not the same, the 7bs are 10" and the 8bs are 12", they are also made a little different, sorry.:sigh:
 
Just finished my Nova 8b's. The improvement is just great. The high's and mid's are astounding. I'm glad I kept these. Now I have to update the Optimus 5b's that I gave to my sister. Thanks for the time and effort.
 
jhsmith123 said:
Just finished my Nova 8b's. The improvement is just great. The high's and mid's are astounding. I'm glad I kept these. Now I have to update the Optimus 5b's that I gave to my sister. Thanks for the time and effort.
Click to expand...

Wow, I've gotta stop procrastinating and pick up the 5b's I've got on hold :banana:.
When they're finished, they'll have some new terminal plates and separate boards for the woofer and mid/tweeter crossover parts. I have some terminal plates (bi-amp type) just laying around and I like to give my x-over parts plenty of room so separate boards should accomplish that.
 
videolady201 said:
None of that will work, the induction is magnetic. Did you check the ohms of your tweeters? Im interested to see what they read, I think that is where the main problem is. Also, did you wire them out of phase?
Click to expand...

The Tweeter measures 7.3 ohms, the mids together 7.6 ohms. The mid and the tweeter are connected out of phase. The woofer is connected in phase-
 
Question

Buttercup said:
The Tweeter measures 7.3 ohms, the mids together 7.6 ohms. The mid and the tweeter are connected out of phase. The woofer is connected in phase-
Click to expand...

I did send you a PM. Also, did you bypass the switches on the mids and tweeter. I don't remember if I posted that, but they should be out of the circuit with the new crossover.
 
What are the B woofers better than non B ones?
Seems to me the cast metal ones would have less resonance?
 
Woofer Info

tmblack said:
Why is the Nova 8B woofers better than the non B ones?
The cast metal ones look more solid?
Click to expand...

The cast frame is nice but the B series has a much stiffer cone. It has small rocks/colored glass glued to the center of the cone for mass loading and to stiffen the cone! The B series also has a brass VC. This is not to say the non B series is bad at all or in any way, it's just the features in the B series is what the crossover was designed for! Hope this helps!:thmbsp:
 
That's very helpful VL.
Would the super glue treatment work well on the non B woofers?
Or is there a suitable replacement woofer one can buy new?
 
None B Woofers

tmblack said:
That's very helpful VL.
Would the super glue treatment work well on the non B woofers?
Or is there a suitable replacement woofer one can buy new?
Click to expand...

The super glue treatment would work great on the none B versions! I would use the none fuming type or odorless SG. It dries slower and makes a better looking job.
 
You must log in or register to reply here.
Back
Top Bottom