Maurbacs NS6 MTM

[rdv]

Re: Maurbacs NS6 MTM

Thanks Don! I'll keep your pointers in mind when I begin cutting. What do you mean by a circle jig for my jigsaw?

[donradick]

Re: Maurbacs NS6 MTM

Thanks Don! I'll keep your pointers in mind when I begin cutting. What do you mean by a circle jig for my jigsaw?

Something like this should work well:

http://www.youtube.com/watch?v=q0plsAARgMA

and a slightly different approach:
http://www.todayshomeowner.com/video...ompass/#tabs-1

You CAN cut speaker holes freehand, but with a little extra work up front, you will make sure that you have no problems later.

[rdv]

Re: Maurbacs NS6 MTM

thanks Don!

[photoprashanth]

Re: Maurbacs NS6 MTM

Hi Don,
I have done progress in building the Maurbacs. Actually they are sounding great.
Following are some pictures. Only veneering is pending.



Since I did not manage to get 1" thick open cell foam in my place, I have padded the foam with some polyfill on the walls. Since I did not get correct sized pipe for port, I used a plastic container which measured very close to the specification.


This is my crossover. I have used locally available Capacitors (Polyester) and Resistors. Inductors are hand wound and measured using LIMP software. They are within 5% variations.


Listening impressions: First of all, I do not have golden ears and I do not have access to many items required exactly as described by you. In spite of these drawbacks, they are sounding really nice and much better than my previously owned Yamaha tower speakers. Vocals are amazing. The sound is clear and crisp. I am loving these speakers. I am just waiting to get some free time to build center channel and a pair of Aurbacs to complete my HT.

Thanks a ton for your help. I will come back to you for center channel speakers for port calculations.

Regards,
Prashanth

[donradick]

Re: Maurbacs NS6 MTM

Hi Don,
I have done progress in building the Maurbacs. Actually they are sounding great.
Following are some pictures. Only veneering is pending.

[ATTACH=CONFIG]30920[/ATTACH]

Since I did not manage to get 1" thick open cell foam in my place, I have padded the foam with some polyfill on the walls. Since I did not get correct sized pipe for port, I used a plastic container which measured very close to the specification.
[ATTACH=CONFIG]30921[/ATTACH]

This is my crossover. I have used locally available Capacitors (Polyester) and Resistors. Inductors are hand wound and measured using LIMP software. They are within 5% variations.
[ATTACH=CONFIG]30922[/ATTACH]

Listening impressions: First of all, I do not have golden ears and I do not have access to many items required exactly as described by you. In spite of these drawbacks, they are sounding really nice and much better than my previously owned Yamaha tower speakers. Vocals are amazing. The sound is clear and crisp. I am loving these speakers. I am just waiting to get some free time to build center channel and a pair of Aurbacs to complete my HT.

Thanks a ton for your help. I will come back to you for center channel speakers for port calculations.

Regards,
Prashanth

Wow! Those are looking great! I can't begin to appreciate the difficulties you face in sourcing components and materials.
The filling looks great, and I really like your front port. I have also made ports from a variety or materials.
The LIMP software program is one of the great "secrets" of this hobby - as you probably know, you can also
use it to measure Theile/Small parameters and box tuning. Nice job on the crossovers also.

[piazzafatb]

Re: Maurbacs NS6 MTM

Hi Don.
Already made Aurabaks and after break in they sound super, thanks.
Want to build a narrow tower of the Maurabaks. Can 6.5 or 7"front baffle can affect too much?

[donradick]

Re: Maurbacs NS6 MTM

Hi Don.
Already made Aurabaks and after break in they sound super, thanks.
Want to build a narrow tower of the Maurabaks. Can 6.5 or 7"front baffle can affect too much?

I'd advise no less than a 7 1/2 inch width. That's what I have on my Maurbac center channel, and it
sounds pretty good. Of course this hobby is all about "I think I'll give it a try ......"

[xenzmann]

Re: Maurbacs NS6 MTM

donradick,

Found this thread after deciding on a simple MTM for use in a HT setup, using the closeout Aura ns6-255-8a + Vifa BC25SC06-04. I ended up putting them into a box similar in size to yours at 8.5x10.5x18.5 external measurements constructed of 3/4" hardwood plywood. Gives very close to 0.75 ft^3 internal. 1.5" diam, 6" long port.

Raw box looks like this (routed & glued, not sanded or finished):


Design goal was a relatively flat response from 100 Hz up and everything basically in phase at listening distance of between 2 and 3 meters. The spacing of the Aura's worked out well for that. Placement is at listening level, close to wall but not mounted on it.

With some tweaking of the crossover the response is decent, as shown below. The Aura is green, the Vifa is red, and the overall is blue. Responses curves are relative not absolute, sensitivity differences taken care of in xover. Given the test environment (garage w/ concrete floors) there are many multipath and resonance nodes from 600 Hz down that aren't as extreme in target environment.



I've got to admit, my xover looks nothing like yours. Given BSC together with the generally rising response of the Aura, I ended up with a pretty heavy inductor to flatten it out. I tried many different combinations of additional filters in the circuit, but didn't get any measurable improvements over a relatively simple 2nd order. Schematic below.



Was there a reason you went with a notch filter on the M's instead of a lowpass? I'd think that with their wide frequency range the Aura's would start to work their way back into the high frequencies.

Thanks for great info in this thread, it made great reading while the sawdust settled and the glue dried.

Xander

[donradick]

Re: Maurbacs NS6 MTM

donradick,

Found this thread after deciding on a simple MTM for use in a HT setup, using the closeout Aura ns6-255-8a + Vifa BC25SC06-04. I ended up putting them into a box similar in size to yours at 8.5x10.5x18.5 external measurements constructed of 3/4" hardwood plywood. Gives very close to 0.75 ft^3 internal. 1.5" diam, 6" long port.

Raw box looks like this (routed & glued, not sanded or finished):
[ATTACH=CONFIG]31177[/ATTACH]

Design goal was a relatively flat response from 100 Hz up and everything basically in phase at listening distance of between 2 and 3 meters. The spacing of the Aura's worked out well for that. Placement is at listening level, close to wall but not mounted on it.

With some tweaking of the crossover the response is decent, as shown below. The Aura is green, the Vifa is red, and the overall is blue. Responses curves are relative not absolute, sensitivity differences taken care of in xover. Given the test environment (garage w/ concrete floors) there are many multipath and resonance nodes from 600 Hz down that aren't as extreme in target environment.

[ATTACH=CONFIG]31175[/ATTACH]

I've got to admit, my xover looks nothing like yours. Given BSC together with the generally rising response of the Aura, I ended up with a pretty heavy inductor to flatten it out. I tried many different combinations of additional filters in the circuit, but didn't get any measurable improvements over a relatively simple 2nd order. Schematic below.

[ATTACH=CONFIG]31176[/ATTACH]

Was there a reason you went with a notch filter on the M's instead of a lowpass? I'd think that with their wide frequency range the Aura's would start to work their way back into the high frequencies.

Thanks for great info in this thread, it made great reading while the sawdust settled and the glue dried.

Xander

Glad you found it useful.
In many ways the crossover on these was an evolution of the Aurbacs (my first solo design). I was never happy about the complexity of that crossover, and one of the guys here suggested a small cap across the woofer coil. I measured that and played with some variations, and it measured great, and was simple.
I'm not going to second guess your woofer inductor value. I've recently struggled with BSC on a new design, and it can be a bit tricky to get it right. I listen to the Maurbacs regularly, and really like the bass, so for my ears, it's "right".

BTW, I haven't seen you before. Nice use of Holm and Speaker Workshop! Been doing this a while?

[xenzmann]

Re: Maurbacs NS6 MTM

BTW, I haven't seen you before. Nice use of Holm and Speaker Workshop! Been doing this a while?

I've built a few small speakers, all under 1 ft^3. In addition to Holm and Speaker Workshop, I find Jeff Bagby's "Passive Crossover Designer (PCD)" an essential tool. I've found DL4YHF's Spectrum Lab to be a useful tool for testing. I also have written my own software for tone generation and spectrum analysis. Of course, there's few things more important that ears, a voltmeter, and a calibrated mic.

Another tool from Bagby that I wish I'd found earlier is his "Response Modeller". I took the spec sheet F/R for the Aura, processed for BSC and port tuning, then saved the resulting F/R. Pulling that F/R into PCD gave a result that was quite close to what I was measuring and quite different than the response I got using the spec sheet values directly in PCD.

The only speaker build I might write up is one I did using an Eminence Beta-8A together with a Selenium D202Ti (not the D220Ti) on a 8" round waveguide. Drivers moderately priced, sensitivity and quality high for both.

[nightrider]

Re: Maurbacs NS6 MTM

could this design work good with the vifa DX25TG09-04 1" FABRIC DOME TWEETER

[donradick]

Re: Maurbacs NS6 MTM

The DX25 would probably work well, but it would require a new crossover design. If you haven't done that before, it's not that hard to get a crossover that's "ok", but pretty difficult to get a crossover that sounds great. The Maurbacs sound pretty darn good as designed.

[vuykfuttydty]

Re: Maurbacs NS6 MTM

Hey Don! DOn't know if you'll respond since this thread is a tad old, but I was looking to make something exactly like this. My drivers will all be lined up vertically with the Vifa in between the two NS6s just for visual effects. I bet i can get the 44 liters built as you recommend for an extendedbass, but I was wondering where your port was? Im planning to mount my port facing bottom since these speakers will be elevated and hung from the sides. I shall try your 3" by 3.25" port too.

Another question was, I ddidnt really understand the crossover schematics for the two NS6s. How come the cap and the inductor are in parallel? Oh and what is the crossover frequency for that?

Plus, would 300W to each set be plenty or too much?

Im just a kid, so i'd gladly appreciate all help. I've built only two speakers before and still in a learning process xD

[donradick]

Re: Maurbacs NS6 MTM

Hey Don! DOn't know if you'll respond since this thread is a tad old, but I was looking to make something exactly like this. My drivers will all be lined up vertically with the Vifa in between the two NS6s just for visual effects. I bet i can get the 44 liters built as you recommend for an extendedbass, but I was wondering where your port was? Im planning to mount my port facing bottom since these speakers will be elevated and hung from the sides. I shall try your 3" by 3.25" port too.

Another question was, I ddidnt really understand the crossover schematics for the two NS6s. How come the cap and the inductor are in parallel? Oh and what is the crossover frequency for that?

Plus, would 300W to each set be plenty or too much?

Im just a kid, so i'd gladly appreciate all help. I've built only two speakers before and still in a learning process xD

Hi dude,
Glad to see your interest!
Port will be fine on the bottom, but you should have at least 3 inches (port diameter) from the port opening to
any boundary. Crossover is about 2. Khz. the cap across the coil drops the NS6 breakup mode at 5Khz way down.
300W will be fine, but you will probably never want to turn it up even half way. These are pretty efficient, but
there are definite limits, and the NS6s will start to distort at high power levels.
We were all kids once, I still feel like a kid compared to the knowledge level of some of the peeps here!

[vuykfuttydty]

Re: Maurbacs NS6 MTM

wow that was fast xD
I will upload my work as it progresses and accredit you for all this valuable information. Thank you!

Actually one more thing... these are to be attached to my jukebox, and I was hoping they would provide enough kick to fill a room with chatting people. Would 100W be per channel be sufficient, considering that the each 100w has to power the two NS6s and the Vifa? Or should I go with the 300, cuz the price difference is significant, but at the saem time i dont wanna blow the drivers.
Basically, how loud will these babies blast?