Crossover Concerns... (NSB - sorry guys)

[Mjr7531]

I'm buying a ton of NSBs (NSBs) and the Onkyo buyouts (269-702) I was wondering, what crossover network should I use? The two drivers seem to be 60 degrees off or so at 6k, where I would like to cross them over. I kinda like having a steeper dropoff, but haven't really heard the difference, I was thinking of doing the NSB at 8 ohms, any input regarding crossovers would be apreciated, thanks,
Matt

[cjd]

6k requires a crazy notch to sound decent IMHO. No reason to go that high.

If you want 8ohm you're looking at a single NSB and a pair of the Onkyos per. Or 4 NSBs, 8 Onkyos. Required for efficiency. I'm not sure you really need to worry about the tweeter impedance so you could do 1:1 fairly safely on an 8ohm stable amp.

I've messed around a good bit with these and find they cross best around 4khz, 4th order acoustic slopes or steeper. This is do-able using only three components in the XO with these two drivers. I have a whole slew of different concepts I've done with these two drivers (though, I've not built with the Onkyo as I have some similar Audax's I'm using).

Oh yeah. You'll want to run a Hilbert transform to get minimum phase. PE's data is accurate, but the phase data isn't good to work with due to the nature of phase data (nothin with their measurements). Once you take that and acoustic offset into consideration the phase relationship will be a bit different.

C

[chipco3434]

How does one do a forth order with 3 components? I am actively working on a project with 4 NSB's and a Dayton Neo tweeter PN ND20TA-6

tweeter

Box is .88 ft^3 sealed. I have caps and coils for 2nd order testing from 4kHz and 5.5kHz.

[cc00541]

I'm assuming you are contemplating an array. If so, then I'd consider running the tweeters near full range. They have negligible Xmax, but there is strength in numbers. This would allow you to cross at around 2.5K and mitigate the lobing effects compared to the 6K Xo you envision. A simple 2nd order acoustic transfer response at 2.5K on the NSB’s will put the break up mode peak at 7K down about –20 dB. Unfortunately not much can be done about the resonance at 1.5K, but it correlates as a dip in the response so likely will not be as noticeable.

C

[cjd]

Originally posted by chipco3434
How does one do a forth order with 3 components? I am actively working on a project with 4 NSB's and a Dayton Neo tweeter PN ND20TA-6

tweeter

Box is .88 ft^3 sealed. I have caps and coils for 2nd order testing from 4kHz and 5.5kHz.

You'll need a bit more with that tweeter, since you'll need a small parallel inductor to tame the bottom end and a series resistor to handle the efficiency difference. IIRC it's something like 4 or 5uF and .2mH inductor, and only a couple ohms. With this tweeter, the NSB really likes an inductor plus zobel over a straight inductor/cap. I actually have parts/plans for a TMM or MTM TQWP at home, just waiting for me to finish up a pile of other projects. As if I need more NSB projects (my HT is full, my office is full, there are others just sitting).

I don't recall the values I'm using at the moment.

Oh yeah... I'm not sure I would try running the Onkyo tweeter full range unless you pair them up. Might cause some impedance trouble too. They're not nearly as capable of taking a beating.

[chipco3434]

[QUOTE]IIRC it's something like 4 or 5uF and .2mH inductor, and only a couple ohms. With this tweeter, the NSB really likes an inductor plus zobel over a straight inductor/cap.[QUOTE]

I would really like your calculated details on this cross. I have a couple kids over as I am writing this and we intend to start playing with crossovers this afternoon. The main project is in a couple weeks but the testing is now.

I can follow instructions but would have difficulty calculating the values for the zobel and coil/caps for this little speaker. I would like to get it right 'cause we are building 16 pairs (with my Sea Scout Ship).

Thanks!

[BillFitzmaurice]

I cross my NSBs to my Onkyos at 6kHz with 18dB slopes and they work just fine, flat within plus/minus 3dB anechoic from 120 to 16kHz

[chipco3434]

Bill...

Just finished first listening tests... the kids think they're "awesome" and I think they're OK but need some room for improvement. Currently running with a cap on the tweets and a coil on the NSB's to get a feel for them

Here's what I get for a second order at 6000. I am trying to keep the cost down so I would like to stay at 2nd order. Perhaps I should move the x-over down to 5 or 5.5kHz to get off that 7kHz bump.

Measured R is 4.8 on the tweeter and 7.8 on the 4 NSB line. They are sounding pretty nice with stuffing in the sealed box. Cones are ready for second coat of spooge and baskets are dampened.

tweet
C1 = 3.9 uF
L1 = 1.8 mH
woofer
C2 = 2.4 µF
L2 = .29 mH

Your input is certainly welcome!

[BillFitzmaurice]

Asdie from the bump of the midwoofs there's also the matter of combing of the system in the frequency overlap zone with the side by side alignment of the drivers, and that's another reason why third order crossovers are going to work better than second. With only a first order I think it would sound quite poor by comparison to even a second order. There's also the matter of phase with second order, if you go that way be sure to check it out. I found the response of my NSBs quite adequate without doing any coating, etc, so since they weren't broken I didn't bother trying to fix them.

[chipco3434]

Asdie from the bump of the midwoofs there's also the matter of combing of the system in the frequency overlap zone with the side by side alignment of the drivers

This is not for the array project. This is for the kids in my Sea Scout Ship. So I will say penance and a good act of contrition for jacking this thread. The 2nd order I'm talking about is for a MMTMM config in a .85 ft^3 box. Thus, I am looking for a simple and cheaper x-over that can be constucted by the yutes.

However, I did read your response on on the McIntosh array, i.e., devoting a line of NSB's to bass and the second to mid-bass which is a very interesting idea ~ especially combined with tapering.

Anyway, your thoughts on the MMTMM project would be greatly appreciated as my online mentor seems to have disappeared into the void of home improvement, kitchen cabinets & ceramic finishes.

As fot the coatings, I have purchased about 300 of these NSB things and there were four of them just begging to be coated!