Maestro center channel

[dynamo]

****EDIT - See post 13 for crossover revision

I got another of my many half finished projects wrapped up. This is a center channel that I originally built about a year ago, but never truly completed until now. I needed a new center that was lower so the tv remote would work without having to point it at the ceiling.

Madtown was clearancing out the Aura NS3-193-8A drivers for about $12 each, so I grabbed four of them. They fit the height requirement, four gave me an 8ohm nominal load, and I thought four of them would look kind of tough arrayed across the front of the tv. I sit pretty close to on-axis , so the horizontal dispersion issues this caused wouldn't affect me too much.

Each driver has about 2 liters, originally vented. I wasn't worried about LF excursion issues below tuning as the NS3's have a fair amount of xmech. The cabinet is constructed of braced 1/2" ACX ply, with a lacquer finish.

I wasn't super thrilled with the sound of just the drivers and no eq, so I had added a notch to deal with the resonance breakup and that made a big difference. Much more listenable.

As time went on, I decided I wanted a tweeter, but still wanted to be simple and budget friendly. I saw the new cheap Dayton PTMini6 planar ribbon and wanted to use it in a project, and this was perfect. It even fit nicely between the current driver layout.

I determined that a sealed enclosure of the same volume would also work decent with the NS3s, So I made removable foam port plugs (and have them in and plan to keep them there).

The NS3 crossover consists of a small inductor with a tank and zobel, to knock down the upper response and deal with breakup, and the tweeter filter is simply a first order; a cap plus a couple resistors. All the parts fit nicely on the back of the terminal cup. I could have done a lot more with the crossover, but this sounds good and was simple and cheap, with few enough parts to remain compact.

I am very pleased with the sound (and look) after the revision with the tweeter. Off-axis seems improved, and it sounds decent and pleasant to listen to. A quick rta check with my iphone and imm6 looks to show a surprisingly flat response. I think the yellow planar on the glossy black gives it a high end look.

I have been using it alone (in 5ch stereo with the amps to fronts and rears off) to listen to while doing things around the house and it works well for that duty as well. I didn't have a chance to watch an action movie with it yet, but am looking forward to it.

Thanks for looking!

[Chris Roemer]

Re: Maestro center channel

your pics are sooo tiny - but, from what I can see, that's a great use for that little tweeter (looks slick as well).

[dynamo]

Re: Maestro center channel

Thanks Chris! I'm not sure what I did there with the pics, I'll see if I can make them bigger.

[Paul Carmody]

Re: Maestro center channel

We demand bigger pics!

[dynamo]

Re: Maestro center channel

Larger pics :D

[Paul Carmody]

Re: Maestro center channel

Very cool concept with the planar tweeter for narrow spacing.

The crossover arrangement alone is worth it for the high res pics.

[dynamo]

Re: Maestro center channel

Very cool concept with the planar tweeter for narrow spacing.

The crossover arrangement alone is worth it for the high res pics.

Thanks Paul! I am real happy with how that tweeter fit. I wish I could say the original design was made for it but was just luck PE brought out this tweeter.

[MattB101]

Re: Maestro center channel

How hard would it be to talk you into posting some cabinet plans and a schematic for the crossover. Oh heck, how about a Parts list too. I think that fits nicely into what I am thinking about doing. Thanks. It looks great! ☺

[[email protected]]

Re: Maestro center channel

Cool.
This design works for me as well. A couple of times I forgot to turn on the amp for the L/R and it took me a while to notice.

[dynamo]

Re: Maestro center channel

Wow, that is nice Arlis! I bet that sounds incredible, sure looks it! Is that the Fountek horn ribbon?

[dynamo]

Re: Maestro center channel

How hard would it be to talk you into posting some cabinet plans and a schematic for the crossover. Oh heck, how about a Parts list too. I think that fits nicely into what I am thinking about doing. Thanks. It looks great! ☺

Sure, thanks! Part of the beauty of this was the value of the NS3s at 50% off. Be nice to find them on sale or clearance again. That got this project done top to bottom for under $100, making it well worth it to me.

Sorry I don't have build pics.. The cabinet is 1/2" material, with internal dimensions of 3*7*24. No dividers, but use four or so dowels top to bottom. I just used some scrap ply pieces though. The dimensions I gave do not include the slot ports, as I recommend it sealed and would do it sealed if I built it again. I would start with light stuffing of fiber fill (I prefer fiberglass, but man does it itch..) Be sure to chamfer the backside of the driver openings for drivers like this so they can breathe. If I did it over again, I would move the outer drivers in closer to the inner drivers. It won't affect the crossover on this particular design as I focused on response flatness and didn't break my neck on perfect phase.

The crossover schematic is attached below as I built it. Looking at it again, I would just eliminate the 1 ohm resistor in front of the tweeter. I will try to make up a parts list, and wont include it. The tweeter cap I used is a buyout cap I had laying around. I would recommend a Audyn Q4 as a replacement; good bang for the buck. Otherwise for this purpose an electrolytic would probably be just fine too. the woofers are wired with two pairs seriesed up to 16 ohms, then parallel the pairs back to 8 ohms.

[dynamo]

Re: Maestro center channel

Here is a parts list for this project. FWIW, I am very pleased with the outcome, however with the woofers at twice what I paid for them it does open doors to potentially superior configurations if you have the space. If you need a low-height option like me, go for it!

Edit-Sorry, forgot to include a terminal cup

[dynamo]

I mis-estimated offset (lesson of the day for me - don't try to estimate offset..) and actually measured it, and made some revisions. This is more correct and accurate than the previous crossover. Nothing earth shattering, just wanted to post the more accurate info.

[bolland83]

Nice work! How are you liking that tweeter so far? I used a pair in my computer speakers with some ND91's, so far they seem like a perfect match for small midwoofers/fullranges. My only complaint is the lack of mounting screw options, I ended up using #2 x 1/2" brass wood screws. I think for another dollar or two they could just include some nice black screws. That said, they seem to perform well above their price point.

[dynamo]

Thanks! Yeah, they should come with screws.. it seems decent. In my application it is a little sibilant which is probably the spike at 5k. I don't blame the tweeter; the crossover is only a cap to keep it simple and small. I'm sure a proper network would do it wonders. I know others here have done very nice small bookshelfs with them.