Maurbacs NS6 MTM

[donradick]

Dear friends, another build has been completed. I've had many requests for a MTM version of the Aurbacs, and results have not disappointed. Very simple crossover, great imaging, and lots of dynamics and good bass.







Port is 3 inch PVC, 3 1/4 inch total length.




Tower plans for that extra bass "love"

[donradick]

If you have been following all the talk about the NS6, you have probably noticed that the measured T/S parameters are a bit different than the published ones. In particular, it likes a bit larger box than you might think. I built this into an existing 33 Liter box, and Unibox models F3 at 54 Hz. If you build a small tower with about 44 Liters, you should be able to get into the mid 40s, but I really don't notice any lack of bottom end.

Due to the desire of some to use this as a horizontal MTM for a HT center channel, I tried to make off axis response as smooth as possible. I figure for an average living room, if you are seated 8 feet away, with a 7 or 8 foot sofa, that's no more than 20 degrees off axis, and the response is very good. Unfortunately, at 30 degrees off axis, it's not very pretty.

[donradick]

Here is the raw, in box measured FR for 2 NS6 woofers. Again, ignore the drop below 500Hz, the woofer is essentially +- 2 dB from F3 to 3K. It sounds pretty good without a crossover, but you have to make sure you roll it off before the spike at 4.5K.




Final FR is basically +- 2 dB, with a measured reverse null of 20 dB. They image very nicely. Ignore the drop below 500 Hz, that's due to the small room where I measure.

[donradick]

This was my second veneer project, and again I can't say enough good stuff about Titan DX contact cement. No fumes, and holds great. Quarter-sawn Maple veneer. I got some great finishing tips from LouC and others, and used a bit of Transtint medium brown in cut shellac (yes, it really DID pop the grain), with General Finishes water-based Enduro (really good stuff - I've tossed out the Deft lacquer) .

Baffle is cheap HD ply, couple of coats of shellac, couple of coats of automotive "filler" primer, and a couple of coats of Oiled Bronze Rustoleum.

[donradick]

Here is the CSD for the 2 woofers with crossover. Not too shabby for a $10 woofer!

[Leroy R]

Crap, now I'm going to have to pick up more NS6's.

Nice job. I assume the drivers being offset from center has a purpose?

[woodtradesman_audio]

Holly hell. I want one.

Don, You got PM.

[donradick]

Crap, now I'm going to have to pick up more NS6's.

Nice job. I assume the drivers being offset from center has a purpose?

Yah, I quickly found that with an overall width of 9 1/2 inches and a bevel on the baffle, I needed to offset the woofers to get a tight center to center distance for all the drivers. If you are not planning on a center channel, it would probably work just as well to center all the drivers vertically.

As noted, I got a little more bass extension when using about 20-22 liters per NS6, as I did in the Aurbacs.

[Leroy R]

I understand the moving the tweeter up and woofers down to get the centers as close as possible when it's laying on it's side as a center. It is all three drivers shifted to the left rather than centered horizontally that I was talking about.

[donradick]

I understand the moving the tweeter up and woofers down to get the centers as close as possible when it's laying on it's side as a center. It is all three drivers shifted to the left rather than centered horizontally that I was talking about.

Ah - another good question!

It's called "using what you have" - I had these old boxes leftover from a failed TMM a few years ago, and the internal braces dictated where I could place the woofers vertically. After I finished them, I realized that you could adjust the vertical position of the tweeter by flipping them one way or the other.

[johnnyrichards]

Nicely done, Don. I am sure this will be a popular build as long as stocks of the NS6 hold out

[codycr6]

beautiful build, I am going back and forth on building something similar. I really had in mind to do four Aura's per enclosure to net eight ohms per side and gain dynamics/efficiency, but how do you feel this would work with adjusting the crossover and lobing? Possibly go to a MTMWW setup on a 2.5 way configuration? How are the dynamics on your current setup for theater use? Any help would be appreciated, going back and forth between these and the SAS buyouts for my first major home speaker project (come from car audio).

[donradick]

Nicely done, Don. I am sure this will be a popular build as long as stocks of the NS6 hold out

Thanks Johnny - still digging these NS6s - but my RS150 build blows them away in both bass and midrange clarity. Sometimes price does matter.
Now a firm believer in veneer - not a whole lot of work for great looking results.
I sure have blown some bucks on rattle cans.

[johnnyrichards]

Don, price always matters it is just finding out what that price means So many variables in a driver cost that have nothing to do with the construction of the driver itself for price to be a reliable indicator, basically just a rough guide.

[donradick]

beautiful build, I am going back and forth on building something similar. I really had in mind to do four Aura's per enclosure to net eight ohms per side and gain dynamics/efficiency, but how do you feel this would work with adjusting the crossover and lobing? Possibly go to a MTMWW setup on a 2.5 way configuration? How are the dynamics on your current setup for theater use? Any help would be appreciated, going back and forth between these and the SAS buyouts for my first major home speaker project (come from car audio).

If you haven't done any design / build / measure projects from scratch, that's a pretty ambitious project. You will need a 2.5 design to avoid lobing. If you want to play, you might try the MTM crossover, and just use a 1.5 mH on the WWs, or maybe a coil plus 8 uF cap to ground, but you could easily end up with a bump or dip around 400 Hz that would be ugly.

If you build these are as they are designed and high pass them at 80 Hz for home theater use with a sub, they will play very loud. I haven't heard the SAS drivers, so YYMV. Without a sub, they will play pretty loud, but not to "head banging" or "ear splitting" levels.

[donradick]

Don, price always matters it is just finding out what that price means So many variables in a driver cost that have nothing to do with the construction of the driver itself for price to be a reliable indicator, basically just a rough guide.

As always, right on the money. I am definitely into high value designs, but realize more and more how many hours it takes me to do a proper crossover and build a box, so really cheap drivers don't seem as important when considering 30-50 hours of my precious time on other aspects.

[codycr6]

If you haven't done any design / build / measure projects from scratch, that's a pretty ambitious project. You will need a 2.5 design to avoid lobing. If you want to play, you might try the MTM crossover, and just use a 1.5 mH on the WWs, or maybe a coil plus 8 uF cap to ground, but you could easily end up with a bump or dip around 400 Hz that would be ugly.

If you build these are as they are designed and high pass them at 80 Hz for home theater use with a sub, they will play very loud. I haven't heard the SAS drivers, so YYMV. Without a sub, they will play pretty loud, but not to "head banging" or "ear splitting" levels.

Have you had any issues driving these speakers? Can you elaborate some on their sound as you built them? I do already run a subwoofer on the low end, I was mainly looking at whether they would be plenty strong down into the midbass region. Measurements and subjective thoughts would be greatly appreciated!

[ryanbouma]

Cool! I really outta grab some of those n6s woofers.

What makes you think the 500hz dip is from the room?

It looks like the 800 to 1000hz region could come down with a larger choke..?

[donradick]

Cool! I really outta grab some of those n6s woofers.

What makes you think the 500hz dip is from the room?

It looks like the 800 to 1000hz region could come down with a larger choke..?

In many ways, I'm still a n00b about measuring - using ARTA in my small study, I get about 300 hz before reflections (about 46 inches or so from boundaries) - so I know that below 300 Hz is not valid, and I read a comment somewhere that said the gating effects will show in the graphs up to an octave above the gate. OTOH, I designed these with about 3 dB of BSC, so there will be drop from 1000 hz down to about 300 hz, so maybe that's what I'm seeing. I certainly don't hear any lack of output in that range - male voices and such are strong and clear.

I really need to get comfortable in ARTA with doing gated at 1M, nearfield woofer, and port measurements and splicing them. Maybe I need to "bit the bullet" and switch to Holm Impulse, where I can combine graphs easily.

While measuring and tuning the crossover, I did try a 1.5 mH coil versus the 1.0 mH I used in the end. Here is the measured difference:

[donradick]

Have you had any issues driving these speakers? Can you elaborate some on their sound as you built them? I do already run a subwoofer on the low end, I was mainly looking at whether they would be plenty strong down into the midbass region. Measurements and subjective thoughts would be greatly appreciated!

No issues driving them, they are a solid 4 ohm design.
Mid-bass is excellent, make voices, guitar, and snare drums sound great - not hollow, or muffled, or chesty. just right.