Realistic Nova 8b Rebuild & Crossover Re-Design

[Gnesen]

Not that I can think of. I'd start with checking the impedance. If something's amiss in the readings you *could* hook them up directly to an amp to check them with a tone generator (I use a smartphone app). You would need to be VERY careful not to blow the drivers -- start at very low volumes and bring it up slowly until you can hear the tone..

 

[geepee]

Not that I can think of. I'd start with checking the impedance. If something's amiss in the readings you *could* hook them up directly to an amp to check them with a tone generator (I use a smartphone app). You would need to be VERY careful not to blow the drivers -- start at very low volumes and bring it up slowly until you can hear the tone..

i better disclose this photo from a poster in this thread. I used it because it was the easiest to understand.
Do you think it is correct?

 

[geepee]

Ok i just tested all the tweeters and mids. They all tested fine except one mid on the left speaker. It was racing between 5.7 and 16 ohms up and down, up and down. Whats that all about? A couple had some corrosion on the magnets which i believe some owners have noticed. There are no signs of moisture around them our anywhere in the cab.

 

[geepee]

I cant imagine this one erratic midrange can be cheaply fixed. Anyone out there have an extra?

 

[notas]

I cant imagine this one erratic midrange can be cheaply fixed. Anyone out there have an extra?

I think I do! I'm away right now but if you can't find one elsewhere I could get it to you eventually.

And do be careful with the wiring, I have wired my mids wrong and not noticed immediately before. They just sound kind of bad, but you don't immediately realize something's outright wrong.

I also have 3 extra woofers that are varying degrees of 'slightly' off, if anyone wants them... Should test with mm.

 

[geepee]

Thank you ir. check it out when you get back. No hurry. I wired the mids back up just like they were stock the rest is wired like the photo i posted a few above. Hopefully that all checks the boxes off. I am a little puzzled to what i may have done wrong.

 

[Bigkahuna]

i better disclose this photo from a poster in this thread. I used it because it was the easiest to understand.
Do you think it is correct? View attachment 870897

I never understood how doing a crossover this way could work. I am a big fan of soldered connections instead of crimped connectors. My focus however would be using the screws and nuts attached to wood as posts for an electrical connection. Wood can conduct some electricity so would not the wood then become part of the circuit, (not good)?? I mean we are talking about pretty small amounts of voltage and current and I would be concerned that the wood is bleeding off some of the voltage and current. Even if you did not have the skills to solder wires why not just use butt connectors and eliminate all of the screws. Just my thoughts.

I also had a pair of Optimus 5B and simply recapped them with Dayton audio film caps. I had them sitting side-by-side to a pair of KLH 5s that also had new film caps. Many people listening thought the Realistic speakers sounded better. I think the Realistic Optimus 5B simply were tuned to produce a little more bass but they were very nice speakers indeed. I currently have a pair of 8Bs that are in absolutely mint condition. I have always considered doing this modification but it is a lot of money to spend on a Realistic speaker that does not get much press.

 

[geepee]

Yes i wondered that too about crimping but i found it easier to follow what is being done more this way than a circuit board. I made sure all connections were uber secure. I just kept on thinking everytime you see inside a pair of speakers the clip connectors to the drivers are....crimped not soldered. Your speaker wire to your speakers are usually screwed on, clipped or squeezed into place and still the sound is beautiful. I just didnt think it would be a big issue to build a crossover this way. I used pressboard for mine. Here it is

 

[Bigkahuna]

I do not know whether it is right or wrong I am just questioning. Perhaps someone else can chime in about their thoughts. I do see a lot of people doing it this way. You have a lot of nice parts there it's a shame it didn't come out to your satisfaction.

 

[geepee]

Yeah its frazzling but i will go over it one more time. I was super careful following everything over and over. But i must have screwed up somewhere. I read how people are so impressed with changes but mine are marginal. It seems like a lot of past posters here have long moved on from this thread. Is this mike on? Hello? Oh well, must press on.

 

[drumbum]

I do not know whether it is right or wrong I am just questioning. Perhaps someone else can chime in about their thoughts. I do see a lot of people doing it this way. You have a lot of nice parts there it's a shame it didn't come out to your satisfaction.

I would have the same concerns. I have two moisture meters, and of course they function by passing current through the wood.

 

[Dizzydre21]

Hi all,

I posted a few things in this thread a couple of months ago and just finished buttoning everything up. I have certainly noticed an improvement in sound quality. I did, however, want to verify with anyone who knows that the tweeter and mid range speakers are out phase from the woofer. That is how the original schematic looks to me. Basically, the positive terminal on the tweeter goes to the return. The mid range speakers are the same, but in series with + on one going to - on the other. Is this correct?

 

[Dizzydre21]

Hi all,

I posted a few things in this thread a couple of months ago and just finished buttoning everything up. I have certainly noticed an improvement in sound quality. I did, however, want to verify with anyone who knows that the tweeter and mid range speakers are out phase from the woofer. That is how the original schematic looks to me. Basically, the positive terminal on the tweeter goes to the return. The mid range speakers are the same, but in series with + on one going to - on the other. Is this correct?

Nevermind!! I just saw that it was in the same post as the schematic!!

 

[jkelleher]

Hi everyone. I know I'm very late to the dance with my first post to this long and distinguished thread. I found a pair of Nova 8b's at a 2nd hand shop a couple years back, Googled them on my phone to see if they were any good and came upon this tread, which prompted me to buy them with the intent of doing this mod. Fast forward and I've recently completed the mod to each. Did an A-B comparison before modding the 2nd speaker, and noted that there was more distinction perhaps in the mids, but seemed to have lost much of the highs (which I take it was one of the designed outcomes of the mod). Just now have done a comparison between both modded 8b's against a pair of Ohm Walsh 2's (both being fed from the same source, and switchable back and forth via an A-B switch). Sorry to report that I'm much disappointed with the modded 8b's; they sound quite muffled in comparison, as though I had thrown a blanket over the Walsh 2's. Every aspect seems to be suppressed - highs, mids and lows, and not just in comparison to the Walsh 2's. I had tested each driver beforehand and found them within specs, followed VL's instructions properly I believe (including wiring the mids and tweeters out-of-phase), but just can't imagine that what I'm hearing is the highly-praised result of this mod that others have expressed. Perhaps I've gone amiss somewhere in the process. Any feedback would be appreciated. Attached are a pics of one of my modded crossovers, before and after wiring in the drivers. THANKS!

 

[DonQuixote99]

What I hear of the Ohm Walsh 2 is they are extra good speakers, and may humiliate all sorts of opponents.

Suppressed may be an effect of 'less efficient,' you're certainly going to have to adjust level when A/B testing to give the Novas more juice--they are very inefficient when modded.

Beyond that, the claim isn't that the Radio Shack critters become the best in the land with this mod, but simply that they are improved. And that lots of people have gotten to do a scratch building project who weren't already into the DIY end of the hobby....

 

[jkelleher]

What I hear of the Ohm Walsh 2 is they are extra good speakers, and may humiliate all sorts of opponents.

Suppressed may be an effect of 'less efficient,' you're certainly going to have to adjust level when A/B testing to give the Novas more juice--they are very inefficient when modded.

Beyond that, the claim isn't that the Radio Shack critters become the best in the land with this mod, but simply that they are improved. And that lots of people have gotten to do a scratch building project who weren't already into the DIY end of the hobby....

Thanks DonQ. Perhaps your right that it wasn't a fair set of speakers to test them against. I will try the same test against a different pair of speakers for comparison. Still, I wonder if I did something wrong in the mod assembly, since they just seem to be so "muted" in general by comparison. I was pushing them fairly good in the comparison with the Walsh 2's; the volume was comparable, but the range of sound was drastically different. Appreciate the feedback, and yes, it was a fun experience having never done such a project before.

 

[nmwhitneyjr]

I wasn't happy with this mod at first. I thought the tweeters were shot or had been damaged in the process somehow. As they played in over 25+ hours, they improved vastly. I've found them to be source sensitive. FM stereo and vinyl sound great... much improved over the stock xovers. Aux sources are shallow on the top end (airplay via iPhone for me... SiriusXM music channels even more so).

Expectations should be reigned in on this mod. I never thought that the xovers would make these speakers flat 20hz to 20khz or even remotely compete with calibrated studio monitors, high end audiophile sets or catch fish THIS BIG.

The improvement is subtle, not life changing.

 

[jkelleher]

Thanks NM. I've read some posts elsewhere about break-in periods for crossovers (strong feelings on the part of both those who believe and those who don't believe it's real); I'll gladly give them some time to see if they "open up" eventually.

 

[Copa1934]

I own dozens of pairs speakers. Each has a sound I like with different genre of music. However, a couple pair excel in general and are my go-to speakers. What I stopped doing was A/B comparisons. To me it's entirely fruitless. The very first thing you HAVE to keep in mind is acclimatization. Our brains and ears are amazing things, capable of discerning many sounds and adapting, often quickly to changes in loudness, amplitude, tone, and so much more. When I listen to one pair of speakers one day and then another on a different day I'm able to appreciate the nuances of the speakers. Because I've allowed my ears/brain to acclimatize TO the speakers I'm listening to, any shortcomings go away or are less apparent. Some speakers requiring more power, others less. More often than not the "efficient" speakers wear on me very quickly, tending to be bright, to me. Less efficient speakers, say AR3a or Bose 901, require more power (the AR less so) to get them really going. I had HPM-100's at one time, but they became intolerable with the highs. Even with level controls adjusted. That's not to say a bad speaker, not at all. Once in a while I have two pair of speakers that compliment each other when run together. Want to rattle the house? Pair of AR3a and HPM-100 in unison. Yikes.

 

[notas]

Expectations have definitely gotten out of control. I love my 5bs, but when I listen to them I listen to them for what they are - sleeper radio shack gear from the 70s. Copa's comment about acclimatizing is quite wise. Once you accept the flaws, you can really enjoy the strengths, of which they have many.