# Dayton ND91-8 in .04cuft Flat Packs



## fusseli (May 1, 2007)

I'm building a pair of speakers for my computer room. Design criteria are that they need to be compact (to be stand mounted), extend below 100Hz, and have a perception of high quality and high SQ. The goal is essentially a "micro monitor," to which the Dayton ND series fits the bill well. 

I chose the ND91 because it works well in the tiniest of boxes and still has decent high end. The PE 0.04cuft knock-down cabinets are a decent volume that work well for the driver. I paired this with the 1"x4" round port, which was a sacrifice of convenience. Ideally the cabinet would be a little larger to be able to accommodate a slightly lower tune, but oh well it still accomplishes the project goals of LF below 100Hz. The flat packs along with a 1"x4" port put the tune near 100Hz, which modeling shows to have a peak around 100Hz. If I went sealed, the -3dB point would be up in the 120-150Hz range and I am afraid that wouldn't be adequate for a good, low, crossover to my computer sub (JL 8W7 in 1cuft sealed). I'm hoping for a 80 or 90Hz crossover point.

I quickly ran through Response Modeler and PCD to see what the response would look like using traced manufacturer data. I sized a simple LCR contour filter that decently flattens the response while factoring in the baffle, making it a proper single driver full range speaker, but I plan to forego this and just use 12-band EQ on my computer along with measurements to do the final tweaking.

Here are my measured T/S for the ND91-8 using DATS:
Re	7.47 Ohms
Fs	94.88 Hz
Qes	0.533
Qms	5.304
Qts	0.484
[email protected] 1.304 mH
Mms	4.617 g
Vas 0.028 cuft


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## fusseli (May 1, 2007)

The knock-down cabinets went together almost perfectly. There were a couple manufacturing flaws that I wasn't thrilled about, particularly a gouge in the routing on once of the baffles, but for what they are and for how they are priced I'd say they are great.

I really wanted to go with a rear mount since I hate the way the stamped basket looks on the mounting flange of the ND series. I am shocked that so many people don't seem to agree, based on all of the front mounted NDs out there. I originally planned on using some steel L brackets with nuts welded in place to secure the baffle with but it turns out there isn't enough room around the woofer to get the lower two corners. I opted for wood screws drilled into the upper and lower walls, not by first choice but it will work.

Cabinets are lined with 1/2" acoustic foam, I am currently experimenting with the tune trying to see if I can get it any lower by adding fill. The ports will face downward and I left enough room on the baffle to later add a low profile tweeter like the ND28, if deemed necessary.


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## Mike Edwards (Mar 10, 2011)

wow, those look nice


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## fusseli (May 1, 2007)

I have completed construction and have them mounted for initial testing and verification. Using DATS, I was able to confirm a tuning of about 95Hz with the foam lining and a small amount of stuffing. WinISD was showing a tune of something near 110Hz with the 1"x4" port, so I'm calling it a success. I'd like it to be lower but there is such a tiny amount of cabinet volume it's hard to arrange more stuffing without choking the woofer or the vent.

I've fired up REW and taken some sweeps and it looks like the 80Hz crossover point will be doable with some EQ at 125Hz, otherwise 100Hz will do. The transition from these guys to the sub is smooth and transparent. I will keep playing with EQ. Overall FR isn't as flat as I was hoping but these really do sound good as-is with EQ. I haven't decided if I will add a tweeter or not.


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## bbm (Oct 1, 2013)

fusseli said:


> I really wanted to go with a rear mount since I hate the way the stamped basket looks on the mounting flange of the ND series. I am shocked that so many people don't seem to agree, based on all of the front mounted NDs out there.


AGREED !! It looks awesome !! I was going for a build with a woofer from the classic series, but after seeing this, I changed my mind.... it looks GREAT !! (Kinda like Audioengine and some others...)

I was going for a 2-way, how much do you miss a tweeter ??


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## Owen Bartley (Oct 18, 2006)

Great looking little speakers, Russ. I'm also curious if you miss having a tweeter with them. These could be perfect for a "small, simple" garage project I've been considering. I like how the speaker mounts from the rear of the baffle, it gives a really clean look.


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## fusseli (May 1, 2007)

They sound really good how they are now. The fact is that I do miss a tweeter with them, and the top end response isn't the best according to my UMM-6 and REW. I will try and remember to post measurements for you guys to see. I have been thinking of adding a tweeter, perhaps an ND20FB to match the look. This is also part of why I wanted to listen to them for a while before finishing them. 

I am happy with their performance as-is and for a budget-minded build I'd personally deem them okay as full-rangers as long as you add either an LCR contour or use EQ like I am.


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