Fun with the new ND Passive's - The Passive Aggressives

[mga2009]

Can anyone confirm if this is an 8ohm or 4ohm speaker?

My poorly understanding of this diagram, tells me it's an 8ohm speaker:
http://techtalk.parts-express.com/fi...tch?id=1370583

But the impedance curve shows values closer to 4ohm...

[djg]

I just submitted the same order. The Jantzen coil is the same gauge and inductance, no problem.

[mga2009]

Hi,

I am looking for a pair of little surrounds for my system, and found these while looking the Heliums and Quarks...

These would be used for movies and gaming, hanged from the rear wall. Do you think the location might affect SQ?

I've attached a BOM from PE. Had to replace the 3ohm 5w resistor with a 10W, and the Dayton Inductor 0.15mh with a Jatzen, as both items where not in stock. Is it OK?

Thanks!

[tomzarbo]

Got to hear these at the MWAF yesterday and they were pretty dang impressive! I will be putting a set of these together likely pretty soon.
TomZ

[Jake]

I like the name, quite appropriate! Impressive tuning on a tiny box. I think a kit would do well.

[ceiol]

thank you

very helpful for a novice like me.

[mattp]

Sure, I sent them to you via PM.

[ceiol]

I used my own in-box measurements for my XO design. Phase still isn't perfect but that would explain why you are getting a different curve with your sims.

would you mind sharing your measured FRD and ZMA files? It would be educational for me to play around with them.

thanks in advance!

[Mike Burke]

Oh Yea....I see that now.

Got it

Thanks for the help

[mattp]

Thanks Matt for posting all the details. Great information..Thanks

" Also...the woofer and tweeter need to be wired in positive polarity"

Does that mean the the positive from the woofer goes to the positive of the tweeter ?

No, instead of the tweeter polarity being reversed as the schematic shows, it just needs to be wired normally.

[Mike Burke]

Thanks Matt for posting all the details. Great information..Thanks

" Also...the woofer and tweeter need to be wired in positive polarity"

Does that mean the the positive from the woofer goes to the positive of the tweeter ?

[mattp]

Looks like my next project.

Looking at the schematic....C2 48UF is that right ? or is it a 4.8UF ?
I hate to ask but I'm going to anyway
Do you have a bill of matterials with part #s

Thanks,
Mike

Mike,

Yes that is indeed 48uF. I used electrolytics for everything just to save space. I also used 5W wire wound resistors for the woofer zobel because it is smaller. There is a 50uF in place of the 48uF in the list because we don't have a 48uF that is small. You can parallel two other values together if you want (this is what I ended up doing) but this 2uF difference will amount to nothing in the long run. Also...the woofer and tweeter need to be wired in positive polarity, unlike what the schematic shows. I forgot to fix this when I uploaded the pic.

Parts list:

Two of each of these:

027-420
027-406
027-354
015-3
004-9.1
257-022
257-036
290-224
275-035
091-1245

Four 290-209

One 300-7060

Driver spacing - Everything is centered on the baffle, the tweeter is 1.5" down from the top and the woofer is 2.5" up from the bottom. The passives are centered on the sides but I would recommend offsetting these each by about 1/8" up and down (one passive a little higher, the other a little lower) unless you want to just cut the excess threaded rod off the back.

I mounted my crossover on the bottom but it will also fit on the back if you make it small enough. Be careful that nothing is in the way of the passives such as wiring. I'm making all this sound a lot more complicated than it really is. If you have any specific questions let me know.

[Mike Burke]

Looks like my next project.

Looking at the schematic....C2 48UF is that right ? or is it a 4.8UF ?
I hate to ask but I'm going to anyway
Do you have a bill of matterials with part #s

Thanks,
Mike

[mattp]

Cool. Gotta build these and integrate the new BTmini plate amp!

edit: so I put the drivers and your XO into XSim. I just can't get the phase to align. Also my curve looks a bit different -- I have to change the R2 resistor from 3 Ohms to 8 Ohms to get my FR looking like yours.

I tried using 0, 0.2, 0.4, 0.6 etc for the offset for the ND91-4, but still it does not align the phase.

what am I doing wrong here?

I used my own in-box measurements for my XO design. Phase still isn't perfect but that would explain why you are getting a different curve with your sims.

Very cool, Matt.

They look super... I think this has to be one of the rockin'est 'tiny' speakers out there at this point.
I can imagine that a 5.1 HT system with these and a suitable sub would really knock people's socks off.

It's hard to tell from the pic, but what amp were you using? It kind of looks like it might be hooked up to the new DTA-2.1BT amp? How did that combo perform? I'm borrowing Kevin K's amp hooked to the Bantam speakers using the same driver, and it does have the guts to drive them plenty loud. I've found that the ND91's seem to like a fair amount of power to reach their full output potential.... seems strange for their size, but they just keep getting louder and louder without really complaining.

I'd also love to hear these at the MWAF if possible.

This is exciting stuff if you ask me, I love seeing PR's in motion.

TomZ

Yes Tom that is a DTA2.1, just what we had sitting in that little area in the office. It works well. These will take some power and not complain, I ran them for a while in the lab on an A500 and they didn't miss a beat. I will have them running on an LP1601S at home but I probably won't have them up very loud. Who knows, beer knows no bounds.

These will be on display at MWAF for your audible pleasures.

With tiny dual opposed passives it's especially funny, you can see them both moving if you are looking right at the speaker. The whole thing comes alive...

Thanks for the comments guys!

[Wolf]

I have 4 of the nd90pr myself for some upcoming fun..

Looks cool, Matt!

Later,
Wolf