My Nat P Build

[jmik26]

Background
I started researching speaker builds couple months ago. I narrowed it down to the Modula MTM or Nat P's. Due to money constraints I went with the Nat P.
This is my Third DIY speaker project. My first project was the Lou C Topaz's and second were the Tri Trix which both sounded very good in my opinion. I hoped for the same or better success on the third project (Nat P) considering they are a higher budget speaker.


Problems
** Edit ** Problem was fixed, reversed speaker polarity :banghead:
Doing the research and reading all the positive reviews I have to believe I did something wrong? I think the speakers sound crystal clear but lack in bass and don't seamlessly blend with each other. I know I can't expect them to shake the walls but when my 6.5" 2 way sealed bookshelfs have better bass response there has to be a problem. When I say the speakers don't blend I mean that I can close my eyes and point to the direction of the speaker every time. When I play my topaz bookshelfs with my eyes open you would bet that I had all 6 of them playing, they just fill the room. I am sure there is a term for that but I am just a amateur audio enthusiast, be gentle.


Build Notes
I built the speaker according to the plans on the accomplished thread with the exception that I made them 1/2" deeper to gain some volume so I did have to make them so tall. Originally I built them sealed out of curiosity and not having PVC. Since then in trouble shooting mode I have ported them with a 3" port 11" long with elbow ported out the back. I also removed the damping material off the sides little by little until all of it was removed? Bass response improved but now they bottom out very easy and still have the staging problem, if thats the correct term?

IMG 2365 - Start of the build. Bottom part will eventually hold the crossovers.
IMG 2368 - Showing the recess and the back of the hole rounded over.
IMG 2403 - Showing the caulk added for strength and sealing. Back support added for removable panel to house port.
IMG 2428 - Setup in the room. Unfinished and in testing stages, bubinga veneer awaits..

[jmik26]

IMG 2378 - Crossovers, stainless 10-24 bolts were used and ring terminals. Supra 15 awg wire going to the speakers.
IMG 2395 - Close up of crossovers.
IMG 2399 - I never realized how much Pspice DOS version would help me so much back then, lol.
IMG 2415 - Basic PE foam.
IMG 2416 - Sonic bearer foam.

Since the pictures were taken the foam off the sides of the walls was ripped out.

[jmik26]

Any help anybody could give would be greatly appreciated. Thanks in advance.... Jeff

**Edit**
I just tested the polarity with a AA battery. All the woofers moved out when I hooked them up.

[john trials]

On your crossovers, you are going to be MUCH better off soldering all of those connections. There are SO many places where you can have a bad connection with crimped ring terminals all screwed together. I'm not saying this is where your problem is, but any way you can minimize bad connections, you're going to be better off in the long run. One of the main things I've learned (the hard way) in manufacturing is to reduce the number of electrical connectors...they only lead to trouble.

[ThomasW]

Not seeing your sim for the port it's impossible to comment.

The total lack of any acoustic treatments in the room is shocking, and explains the problems with the high frequencies.

Improper room placement of the speakers (asymmetrical boundary loading, speakers too close to the back wall, etc) along with the lack of acoustic treatments explains the sound stage issues.

Are the crimp-on connectors and all the nuts and bolts made from nickel plated brass? They better be because iron/steel connections should never be used a crossover.

Finally if you want low bass use a sub, not a bunch of 6.5" midwoofers

[jmik26]

Thanks for the comments, I will keep that in mind. I soldered the ring terminals to the components after they were crimped on. Probably a little overkill but better safe then sorry. When I did my Topaz's about 10 years ago I used the bolt method and they are still holding up solid. To me it just seems like a more solid connection.

I have been jamming them out after I did the battery test. Maybe its me but they are sounding better? I actually had to get up to see if the sub was on? Will they sound that bad if they are not broke in? How long does it take to break them in?

[jmik26]

Not seeing your sim for the port it's impossible to comment.

The total lack of any acoustic treatments in the room is shocking, and explains the problems with the high frequencies. Improper room placement of the speakers along with the lack of acoustic treatments explains the sound stage issues.

Are the crimp-on connectors and all the nuts and bolts made from nickel plated brass? They better be because iron/steel connections should never be used a crossover.

Finally if you want low bass use a sub, not a bunch of 6.5" midwoofers

It basically the same as the attached pic used from accomplished thread.

I enjoy music and one day hope to have a dedicated room for listening to audio with all the bells and whistles. However, for now I gotta put everything in my living room and have to keep it toned down.

The nuts and bolts are all stainless.

They are starting to bloom. I actually had to get up to see if I had my sub on. Thats moving in the right direction . Baffling part is I did nothing except move the left speaker back about a foot and test both with a battery?

Maybe I am being toooo impatient?

[jmik26]

I am really scratching my head now :roll: . I must have had the polarities reversed and when I went to check with the battery I hooked them back up the proper way. Its the only thing I can think off because they are jamming now.

[wkhanna]

How long does it take to break them in?

2 to 4 weeks running at least 6 hr a day for mine.

Your bracing looks good. Mine are 65 liter, simiar to yours.
My bottom facing flaired ports are fairly short with good bass, IMHO, considering the 6.5 drivers.

Run them for while and work with room placement.

Keep us posted.

[jmik26]

2 to 4 weeks running at least 6 hr a day for mine.

Your bracing looks good. Mine are 65 liter, simiar to yours.
My bottom facing flaired ports are fairly short with good bass, IMHO, considering the 6.5 drivers.

Run them for while and work with room placement.

Keep up posted.

You have no idea how happy I am to hear that. The more I listen to them the bigger my smile gets, lol. I just listened to Hotel California and swore the sub was on. I am kicking myself for not looking at the wires before I unplugged them for the battery test. Really would have been nice to see what the hell it was. Thanks for the tips... Jeff

[jmik26]

So instead of pondering on it, why not hook 1 of them up in reverse polarity to try and simulate the initial results? So I did and thats exactly what it was! :banghead: Embarrassed and happy at the same time if thats possible.

[jmik26]

Some more info on the build. Now that my mistake has been corrected I have time to enjoy them. Last night I jammed out for about 4 hours. I can actually hear the squeaks in the piano pedals on Diana Kralls CD's 8O . Amazing Speakers! My hat is off to the dark side....

[fbov]

...I can actually hear the squeaks in the piano pedals on Diana Kralls CD's ....

Glad to hear bass issues are resolved; enjoy! This is why you built them....