Radio shack Nova 7 crossover recapping Help needed!

[misternova8]

I have a pair of Nova 7's and i to recap the crossover put i hve no idea of a starting point, can someone point me in the right directions, IE: where and what parts to buy, is it worth it?

 

[shadyJ]

You need to know the values of the caps you are replacing. Can you read the values on the old caps? If not, you will need to get a schematic somewhere, and good luck with that. Those speakers aren't worth the effort.

 

[misternova8]

thanks for that response, i will take it into consideration, i have not pulled the crossover to look at it yet, i guess that would be the first step.

If i pull one crossover and the values of the caps, should i assume that the other speaker has the same value?

 

[zieglj01]

Here you go .... read this
https://audiokarma.org/forums/index.php?threads/realistic-nova-7b-mystery-crossover.827366/

https://www.parts-express.com/dayton-audio-dmpc-15-15uf-250v-polypropylene-capacitor--027-432?AID=1457483&PID=8158976&SID=jxmes10frk02ko3q0005c&cjevent=384ca21f9d1c11e982f001080a240613

https://audiokarma.org/forums/index.php?threads/realistic-nova-7b-recap.841759/

 

[misternova8]

thank you for that info

 

[zieglj01]

thank you for that info

https://audiokarma.org/forums/index.php?threads/realistic-nova-7b-recap.841759/

 

[lovinthehd]

Why would you replace caps when you haven't even inspected the old ones?

 

[misternova8]

Why would you replace caps when you haven't even inspected the old ones?

HERE IS A PHOTO

 

[lovinthehd]

View attachment 30035




HERE IS A PHOTO

Okay, and?

 

[misternova8]

is there anyway to tell if it needs recaps?

 

[lovinthehd]

Other than obvious physical failure (like an exploded/leaking cap) you could test them....but if they sound great why mess with them?

 

[zieglj01]

is there anyway to tell if it needs recaps?

Why not have some fun and replace them, with some poly caps .... change one speaker and test it against the old one ... see if there is a difference to you ... but since you changed one speaker then change the other one .... use the same value for each cap you replace .... if 3.3 then use a new 3.3 ... check the others for their values --- have fun

 

[lovinthehd]

Why not just redesign the crossover altogether? Probably could use some improvement?

 

[misternova8]

i have no idea where to start to redesign the crossover

 

[shadyJ]

i have no idea where to start to redesign the crossover

If you want to understand loudspeakers, I don't think that working on this particular speaker is a good start. I suppose its not bad if you just want to experiment, but the design itself is not good. There is a reason why speaker manufacturers don't make speakers like that anymore; it comes from a time when speaker design was a much less precise art.

If you just want to see what happens, by all means, have fun with replacing parts on the crossover, but keep in mind even by the standards of its day, that was a mediocre loudspeaker. I am not trying to discourage you from having fun with that speaker set, unless you really are after great sound quality, in which case you can do a lot better with almost anything made in the last 25 years.

 

[lovinthehd]

i have no idea where to start to redesign the crossover

I was being facetious, sorry, I can't imagine putting much effort/expense into these speakers at all myself, if they worked I'd leave 'em as is. Just old speakers with far better out there....

 

[misternova8]

ok i will leave them alone and play them until they play out

 

[Swerd]

is there anyway to tell if it needs recaps?

To answer your question…
Your photo doesn't show any obvious signs of cap failure, like a bulging or leaking cap. There are two things you can do to tell if crossover caps should be replaced.

• Measure the frequency response of those speakers. If you had a speaker measurement rig, you probably wouldn't have asked your question. Moving on…
• Measure each individual cap with an LC (inductance/capacitance) meter. LC meters are quite a bit less expensive than what you'd need for the first item. (Search Amazon for 'LC meter') To measure a capacitor properly you must cut it's leads and remove it from the crossover. If its capacitance is within 10% of its printed value, its still good. If not, replace it with a new cap that is within 10% of the original cap. In reality, once you cut the leads to measure the cap, you might as well replace it with a new one.
• Replace them with inexpensive metalized polypropylene caps, such as the Dayton house brand from Parts Express. There is a myth that says different brands of caps, or caps made with different materials, in a speaker's crossover make for different sounds in speakers. On some other audio forums that myth gets great play. Don't get caught up in that. It's no more true than the myth that different speaker wires generate different sounds of a speaker. People may believe such myths, but there is no evidence to support it.

 

[Bucknekked]

If you want to understand loudspeakers, I don't think that working on this particular speaker is a good start. I suppose its not bad if you just want to experiment, but the design itself is not good. There is a reason why speaker manufacturers don't make speakers like that anymore; it comes from a time when speaker design was a much less precise art.

.

@shadyJ
That was a very nice and very kind way to say why waste your time on a crappy design that wasn't much good on the day it was made. Back in the day I couldn't afford much of anything for my audio so I went window shopping at Radio Shack a fair amount. I was broke enough I couldn't even afford most of what they had. I remember these speakers. At the time I thought they were something grand. But, as you pointed out, the design wasn't really very good and after all these years of aging, it won't compare favorably.

But as a DIY practice hack, have fun. Practice up. If you get good at crossover repairs and such, you may have what it takes to DIY a whole set from some of the very fine DIY kits.

 

[zieglj01]

ok i will leave them alone and play them until they play out

Have some fun if you wish, and change those caps to poly caps, this may lead you into some DIY stuff ... this would be the 3.3 uf cap, no need to spend high dollars. It can be fun and interesting.
https://www.parts-express.com/dayton-audio-dmpc-33-33uf-250v-polypropylene-capacitor--027-420