Lightning stikes twice: Another set of zero 9's.

[M Jarve]

I took a trip to Duluth this morning to pickup the next installments of Hellsing from B&N. Decided to hit a couple of pawn shops while I was in town.

The Pawn America had a set of Klipsch KG-3.2's for $299 (passed), and a pair of Advent Laureates for $99 (seriously considered). But I went on to the next one and there were a set of big JVC’s in the window, that were vaguely familiar. Went in and looked at the back panel. JVC model zero 9. Boo-Ya! Swung one around and removed the grille. All the drivers seemed in tact, but the woofer surrounds were totally gone. Looked at the other. Same thing.

I could not find a price on them, so I asked the clerk. She looked them up and said $100. Sold!

I got them home and removed all the drivers. They all tested okay, so now it is just a matter of waiting for new surrounds. One of the mid-woofers had the cone dented out in a peculiar way, but I am hoping a new surround will tame it. It’s not really bad, but it is noticeable. If anyone has a tip on getting warpage out of a carbon-fiber/paper composite cone, I am all ears.

Unlike the ones I had before, these have the original floor plinths and grilles. Although the cabinets are about as beat up as the other set (but not beyond servicing), they look much better with the grilles and plinths.

I figure that with a speaker this relatively rare it was chance that I found the first set, but fate that I found the second.

Pictures to follow.

 

[BridgedToMono]

Very nice, sir. Those sure are some fun looking speakers...

 

[M Jarve]

Here are some pics of the old ones I had; I will post external pics of the new ones later.

 

[thedelihaus]

M Jarve,

Congrats! I look forward to seeing pics- I've never seen these before and am unfamiliar with your post on these in the past.

What happened to the pair you had prior?

EDIT- looks like you beat me to the punch! Just posting while you were putting the pics up...

 

[M Jarve]

The other set originally went into storage after I got the Equasound speakers, and a good friend eventually convinced me that he needed them.

This new set is going to be tweaked a little to make up for some deficiencies I observed in the first set. Most notably, I will be removing the 6,000uFd cap that is in series with the woofer.

One change I noticed from the fist set I had is that this pair does make use of fuse protection. So far this is the only real difference I have noticed.

 

[rgrjit8]

Hey, those look kinda neat!
I'd like you to do a good review when they're up and running.
What's the funny looking midrange or tweeter? Some kind of ribbon?

 

[MarkAnderson]

This new set is going to be tweaked a little to make up for some deficiencies I observed in the first set. Most notably, I will be removing the 6,000uFd cap that is in parallel with the woofer.

Man, you can't make a statement like that and not offer an explanation. Inquiring minds need to know. Spill the beans, already . - Mark

 

[M Jarve]

What's the funny looking midrange or tweeter? Some kind of ribbon?

Indeed, it is a planar ribbon tweeter. Amongst the first, I believe (the zero-line's claim to fame, if you will). 6 super powerful samarium-cobalt magnets, and a ribbon of aluminum coated mylar. The flanges are not just mylar coated plastic, either: Solid, chrome plated aluminum worthy of a McIntosh chassis.

The frames and all the baskets are made of cast aluminum, too. The grilles alone weigh 12-lbs each!

I will be ordering up new foams this week (hopefully on Monday, if I have the time), and while I am waiting, I will be making the tweaks I want (or not), which leads me too...

Man, you can't make a statement like that and not offer an explanation. Inquiring minds need to know. Spill the beans, already . - Mark

The 6,000uFd cap is there, apparently, to limit LF response and excursion, and to prevent distortion. It is right in series (not parallel, as I originally suggested) with the + side of the input. On the last set, I noticed a slightly uneven bass response which I originally attributed to the unique tuning of the enclosure and use of the dual bass drivers. However, further research has shown my original premise to be wrong. It is the capacitor. I talked to an owner of this model of speaker, and he mentioned that the dealer he bought his set from had removed the cap because of similar observations. Simply removing the cap and installing a jumper wire should add more definition to bass and allow for greater LF extension.

The funny thing is, after a glance inside, I do not see the cap. I do remember it specifically on the old set because it was larger than the others and was off by itself, mounted to the rear baffle. Perhaps this version has a revised x-over without the cap? That would account for the addition of the fuse, in my view. If it were there, it would be placed where the fuse is. If that is the case my work has already been done for me.

 

[bolly]

that is fantastic mjarve!

 

[M Jarve]

One more thing I just noticed is that they wasted very little with this system. The woofer cutouts are used to reinforce the top and bottom of the cabinet. I remember my Technics SB-7000A did the same thing.

 

[M Jarve]

Here are pics of the new units, with and without grille. The woofers have been removed for new foam. They're ratehr handsome for being in such neglected condition, I would say.

I put a coat of Scotts Liquid gold on after the pictures were taken, and it helped to eliminate the dull, dry appearance. I also thoroughly vaccumed the grilles and insides.

 

[wualta]

Any idea what the nominal crossover points were/are?

 

[Donkey!]

Those look neat. I would've paid a 100 bucks for those too.
Good score. :thmbsp:

 

[M Jarve]

Any idea what the nominal crossover points were/are?

One source of info I have says that the x-over points are at 450Hz and 5,500Hz, which would make sense if the woofers were the same. Another says 120Hz, 500Hz, and 5000Hz, which make sense since the woofers are slightly different.

There is credence to idea that the woofers are not crossed over with each other in that they are both 16-ohm (or 8-ohms in parallel). I am thinking the lower woofer, with it's cast aluminum heatsink on the voice coil is acoustically crossed over. The upper woofer definitely has more mid-bass presence than the lower one, but the lower woofer provides the deep bass foundation and "slam".

This is a Japanese website describing the zero5, the smaller sibling to the zero 9. It seems like it is just the top portion of the speaker, minus the lower woofer (and associated enclosure). I imagine that the woofer is an 8-ohm one in the zero5

http://page.freett.com/knisi/zero-5.htm

Those look neat. I would've paid a 100 bucks for those too.
Good score.

If only the owner of the pawnshop had known that I would pay many times $100 for them, even in that condition.

 

[wualta]

Thanks for the info. Those ribbon tweets would be lots of fun to play with. I was wondering what impedance they are and then I seemed to recall that they were made by printing an aluminum trace on a Mylar ribbon, so they're not the usual ribbon tweet that needs a transformer. I could be wrong.

 

[M Jarve]

They use an 8-ohm Dynaflat etched ribbon (aluminum and polyimide resin), and have HF extension to "only" 50kHz, not the 60-100k a true ribbon is capable of.

I've torn mine apart, and I have to say that it is an interesting design. The magnets are powerful enough to distort my TV from about 6 feet away. I had to use a vise to get the two magnetic arrays close enough to put the screws back in!

Here is a blow-up pick of the tweeter from that Japanese site.

 

[thedelihaus]

Brave, brave man tearing into the tweeter. Glad it went smooth. I'd have been a nervous wreck opening that up...

By the way, if you poke around that site, lots of other speakers and hi-fi gear come up. May I post it in another forum? I'll be sure to note you proper credit.

http://www.niji.or.jp/home/k-nisi/index.html

 

[M Jarve]

Brave, brave man tearing into the tweeter. Glad it went smooth. I'd have been a nervous wreck opening that up...

I had to. The terminals were loose from the membrane and had to be re-soldered. I did it to the other one too just as a preventive measure.

The solder points on my spare tweeters and the ones from my original set are fine though.

When I get the woogers raccooned, I'll bring my set over to my friend's house and take some pictures of stacked zero 9's! We should need a license to do it.

 

[wualta]

I had to. The terminals were loose from the membrane and had to be re-soldered.

Was that because they'd been overdriven?

They use an 8-ohm Dynaflat etched ribbon (aluminum and polyimide resin)...

So they're made like the original KLH DvR tweets-- aluminum on a tensioned Kapton sheet. An isodynamic tweeter, in other words. How does JVC handle the tweeter's backwave in the Zero9?

 

[Damage]

looks suspiciously exactly like an Infinity ribbon tweeter.