# Dayton ND20FB-4 Saves Me from Blose!



## 6262ms3 (Feb 27, 2008)

Sorry this turned into a wordy post, but here's a bit of a review on using these wonderfully cheap tweeters with a Mazdaspeed3 Bose system to keep my sanity while I save coinage for a proper system. In front the Bose originally had 2ohm paper mids with NO x-overs and 4ohm poly tweets with an 8.2khz cap. The mids distorted like crazy trying to play full-range and the tweets were dull and lifeless. The Daytons practically dropped right into the factory holes and I put a 4khz cap on each. I also got 2 inductors for the mids to low pass at around 3.2khz. Yes it's a poor x-over design but 2 ohm mids didn't give me alot of choice and I didn't want to push the Daytons any lower on a 6db filter. Now for how it sounds: The Daytons blend reasonably well with the stock mids, a bit on the bright side but better than many budget car comps. I'm amazed at the detail and clarity from these things for $12 a pair! Treble has become way more realistic and present, maybe a little hyped on cymbals. Upper midrange detail on vocals and instruments has improved 10-fold and is fairly smooth without much harshness or sibilance, I'm hearing things that just weren't there stock. With the shallow slope they definitely don't like to pushed on rock and punk, but stock the mids distorted so badly I couldn't listen loud anyways. The stock mids are way happier with the low-pass, they still suck but at least now they're tolerable. The big x-over gap creates a hole but not as bad as you'd think, thanks to the shallow slopes. These tweets have impressed me enough that I'm going to start with them for my first-ever active setup, with a 24/db slope and clean power I'm interested to hear how they do. Plus if I make a mistake and toast them the wallet won't suffer. I'm thinking of going with Mach 5 MLI-165's for mids, seems like they'll play to 4khz. To cap it all off I'd say these tweets are perfect for improving a factory system on the cheap and sound better than most big-name budget car comp tweets I've heard over the years.


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## owdi (Apr 4, 2008)

I just designed a passive crossover for the Dayton RS150-4 and ND20FB-4. I haven't built it yet, but I can tell you the ND20 needs much more than just a series capacitor. The tweeter has no ferrofluid, so the impedance peak at fs needs to be addressed. An LPAD helps, and adding a coil for a 2nd order crossover helps even more.

If the tweeter is too bright for you right now, try an LPAD with a 1.5 ohm series resistor and 7 ohm parallel resistor. These would be wired after the series capacitor you have now. Both resistors should be rated for at least 5 watts. This will make the tweeters about 3db quieter, and will remove much of the harshness you now hear with rock.

EDIT: crap, I messed up. This tweeter does have ferrofluid, so a series cap is not all that bad after all. I still recommend the LPAD.

Dan


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## 6262ms3 (Feb 27, 2008)

I thought about making a second order filter and adding an lpad, but this is a temporary setup and I didn't feel like going crazy with it. When I install a full system I can tweak frequency, slope and level electronically, then they'll be much happier. Right now the Bose is pretty low-powered and I have an ok ear for distortion so they should survive. They're not so bright as to be annoying.


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## owdi (Apr 4, 2008)

You said you added a 4khz cap, so I'm going to assume it's 10uF. In that case tweeter response looks like this:










That is not bad at all. If you add an LPAD using a 1.5 ohm and 7 ohm resistor, you get:










If you add an LPAD and parallel .2 uH inductor, you get:










I like the final response best, but I also realize it's would take $5 worth of additional parts, which is what the tweeter cost in the first place 

Dan


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## MiniVanMan (Jun 28, 2005)

owdi said:


> I just designed a passive crossover for the Dayton RS150-4 and ND20FB-4.


How???

The ND20 can't be pushed low enough to mate up well with the RS150 before the cone breakup becomes a serious problem, and beaming on the RS150 will occur. 

Beaming isn't as big of an issue if you're listening on-axis, but the cone breakup on the RS150 is big, massive, and can kill you. 

Even a 24db acoustical slope at 3khz will only have the first peak of the breakup down to about 90db at 1w/1m. That's level with the rest of the bandwidth of the driver. You can notch that peak, but the breakup extends all the way up to 10khz at it's largest peak. That's a full octave of breakup that would be EXTREMELY difficult to apply an all encompassing notch on. 

Yeah, the 24db electrical starting at about 2k is about as high as you'd want to cross the RS150, and the ND20FB just isn't capable of mating up well with that low of a crossover point.

Not to rain on your parade, and I apologize to the OP for this going off-topic, but it doesn't seem a viable match between the two drivers.

To the OP, I really like the ND20FB as well. I've recently used it in a 2-way design myself that's working out very well. The tweeter can be a little hot, but nothing a good L-pad can't correct. Parts Express has variable L-Pads that you can put inline with the tweeter that can help tame it a bit, and I agree with owdi about adding a coil to the circuit. You'll get much more life out of that tweeter. 

It is a good tweeter. Especially for the price.


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## 6262ms3 (Feb 27, 2008)

owdi: What program did you use to model the tweet? I'd love to play around with it as I'm also designing a 3-way home speaker setup.

minivanman: What mid did you pair the daytons with? I'm open to ideas for my budget front-stage but so far the mach 5 mid seems the most cost-effective and tuning-friendly.


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## MiniVanMan (Jun 28, 2005)

http://www.diymobileaudio.com/forum/showthread.php?t=38490

I coupled it with a Peerless 2" midrange. 

I'm not a fan, and in fact absolutely will not use a 6.5-7" driver up to 3-4khz. There's just too many problems that occur with that type of setup. 

So, that pretty much nullifies the ND20 for use in a 2-way that uses a driver larger than a 5 1/4", but even more suited for a 4" 2-way setup.


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## owdi (Apr 4, 2008)

6262ms3 - sorry for derailing your thread  I used Passive Crossover Designer along with frequency response and impedance traces from Zaph Audio.

MiniVanMan - let's take this up in another thread.

Dan


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## Hillbilly SQ (Jan 26, 2007)

i was able to successfully mate my nd20's with my seas cd18's. i had the tweets at 4khz 24db and the mids at 2500 12db. worked fine in my truck in stock locations but i'm sure the cab is helping push the midrange up quite a bit.

/threadjack.


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