SuperZero Clones

[fdorogi]

I'd like to build some NHT superzero clones. I know that used superzero's are readily available on the market, but I don't like piano black. Also, I thought I'd use fresh drivers and build a more substantial cabinet. I found a source for the original NHT spec'd drivers, but no crossovers. Do you really smart DIY'ers know how I can get my hands on a schematic (without buying a pair and gutting them). I'm not comfortable with the challenge of creating a design from scratch - I'm an MechEng, after all.

[JonMarsh]

Did Stereophile ever review them? Stereophile has online archives of a lot of their reviews, going back to the early 80's. They do pretty good reviews, including showing the filtered driver response; are the drivers "standard" parts from some of the big suppliers, or custom to NHT? Might not be that hard to reverse engineer a crossover...

I'm not that familiar with the SuperZero's myself, so I don't have some design lying around. But it wouldn't be that hard to synthesize one, if I had the driver responses in the enclosures. That would mean measuring them in the boxes you plan to build.

Otherwise, try to find someone who has the actual crossover schematic- might be out there somewhere.

Regards,

Jon

[fdorogi]

Jon,

Stereophile reviewed them ten years ago. I found the following:

http://www.stereophile.com/loudspeakerreviews/804/index1.html

The crossover discussion:
"The drivers are crossed over at 2.2kHz with a minimalist crossover consisting of just two small electrolytic capacitors (5µF/50V and 10µF/50V), three resistors, and one inductor. The low-pass feed to the SuperZero's woofer is a second-order 12dB/octave filter, while the tweeter is crossed over with a first-order 6dB/octave slope."

It doesn't give me enough information to go on (not versed in XO design), but a more seasoned designer would get more out of it.

Looks like the drivers were both manufactured by Tonegen to NHT's specs. The mid-bass is a Tonegen 458. I'm still trying to hunt down the tweeter model number.

I've noticed that you love to jump on stuff like this, I don't want to put another project in front of you......

[ThomasW]

That's plenty of data to create the crossover, problem is that it's specific to the drivers NHT uses. So unless you can buy those specific drivers, the crossover data isnb't much help.

There are a ton of other baby DIY speakers around, but they won't have the same sonic signature as the zeros............

[fdorogi]

Thomas,

I've been wanting to get into DIY speakerbuilding for some time. Suddenly, I have access to a limited quantity of leftover, new superzero drivers from a surplus clearinghouse. I've previously auditioned them on two different occasions and they've left me very impressed.

I was thinking that I could give it a go, and try cloning the zeros. I don't have the self-confidence to design my own crossover network So, I was hoping somebody in the forum would know where I could find a schematic. If it all works out, I'll have a fresh set of beech veneered "zeros".....

[ThomasW]

No company I know publishes schematics for products they are currently selling.

You can reverse engineer the woofer XO HERE
You can reverse engineer the tweeter XO HERE

You'll need to have the drivers in order to measure their impedance (or that info maybe printed on the back of the drivers).

You already know the XO frequency, 2.2kHz = 2200Hz.

The resistors they refer to probably create an L-pad to lower the output of the tweeter. You can buy a variable L-pad from most elec parts stores for $5.00, they come with a wiring diagram.

[Wayne A. Pflughaupt]

Why not pick up a pair of used ones on eBay and take them apart to see what’s in the crossover first-hand? After you’re done with them you could sell them and be out practically nothing.

Regards,
Wayne A. Pflughaupt

[fdorogi]

Why not pick up a pair of used ones on eBay and take them apart to see what’s in the crossover first-hand? After you’re done with them you could sell them and be out practically nothing.

Regards,
Wayne A. Pflughaupt

Came to the same conclusion, only a little slower in getting there. I put an offer on a pair posted at audiogon.com - waiting for a reply. Thanks.