# My MTM's



## drf (Oct 22, 2006)

I wanted a set of speakers that were similar to Nat P's but a little smaller so they could be placed in our lounge room when I upgrade whats in the theatre. This required something that has both WAF and decent sound on a budget.

The woofers I used are probably the cheapest you can get in Australia without buying something un-useable. 

http://www.jaycar.com.au/productVie...&pageNumber=&priceMin=&priceMax=&SUBCATID=383

The Response tweeters on the other hand are a more respectable brand.

http://www.jaycar.com.au/productVie...&pageNumber=&priceMin=&priceMax=&SUBCATID=418

As you can see the upper limit of the woofer is 4Khz, so I expect see some cone breakup as low as 1.5/2Khz (or maybe a little lower, it is cheap after all). Although I am hoping against hope that because it is a polycone and only 6" I won't hear it until 2.5Khz. 


The internal cabinet dimensions are: 500x200x350

Some pics: Please excuse the quality of these pics, I'm not a good photographer.
The panels before cutting







the mostly assembled box








And I was sure I took more photos than this, but I checked the camera and I'm afraid the camera says no.

So heres the finished unit in my unfinished theatre room.














I don't like passive crossovers, I have a basic desire not to use them for many reasons. but My current shortage on spare amplifiers and no real desire to build another active crossover has left me in the passive department. So what I decided to do was build the standard 2nd order butterworth and modify it if neccesary afterwards. The inductors I used where the ones I made in the other thread about DIY inductors. And they all seem to be doing what they should.

First couple of tests were:

Slovak Philharmonic playing Sammartini:Sinfonia in A Major,
I love the violins in these recordings, they allow me to listen for tonal quality that I just seem to hear
better than I do with other styles of music. These speakers were a treat for me. I was expecting a little flatter sound, so when my first impression put in mind of the last live concert I attended I was very happy.

Bach, Toccata and Fugue in D minor,
Organ works will show almost straight away how well a system handles the lower registers. as you may guess with $24 drivers they didn't present well at all for organ music, They didn't have the eveness across the lower registers 35 to 60 hz to make an impression. I might be a little harsh on them as my last set of speakers were 12" that could easily rattle the windows at 25Hz.

Mira Yevtich-Richter, Piano
Daquine - Le Coucou & Bach - Jesu joy of mans desiring,
Piano really shows how good a system can reproduce mids and can frequently unearth resonance issues.
what has stood out is something around the 1.5Khz to 2.5 khz range, It doesn't sound like cone breakup or resonance but it has similarities to each. I inttend on doing nothing about it until I get some more room treatement in. That way I hope I will better pinpoint the issue.

Finnaly for those who like pretty graphs:







Although I wouldn't put too much weight in this one as it is an in-room reading on an un-calibrated mic. However it does serve to give a rough idea on what is going on at the crossover (remember it is only a basic XO). The one thing this graph does show that is also present in listening tests and was also predicted is the higher output from the tweeter. This is becasue its 4dB more sensitive than the woofers and no allowance has been made for it in the XO. The dip at 3Khz starts right on the crossover point looks like I might have to do something there. 

Over all I am very happy with these speakers, for a little less than A$250 the pair They out perform a lot of what I have heard around the traps. Of course I am biased :dumbcrazy:


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## Owen Bartley (Oct 18, 2006)

drf, ths pics aren't working for me but I'd love to see what you put together. I'd always be up for some inexpensive projects if I could just find somewhere to use them. I need friends with speaker deficiencies to pass things on to! Anyway it sounds like a great project for the money invested, and I'll check back to see if I can get to your attachments.


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## drf (Oct 22, 2006)

Thanks, the attachments didn't work when I started the thread, so I messaged a moderator. I might have to re-attach them or something.


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## drf (Oct 22, 2006)

O.K got the attachments fixed, Thanks sonnie.

If I can get a better pic of the unit I will, I didn't realise just how bad these pic are.


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## terry j (Jul 31, 2006)

what would be the reason for the evenly spaced 'spikes' in the bass??? but not the tweeter.


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## drf (Oct 22, 2006)

terry j said:


> what would be the reason for the evenly spaced 'spikes' in the bass??? but not the tweeter.


Interference most likely, my test mic and gear has been slowely getting worse over the last couple of years. Usually I only use it to test how a speaker/amp reproduces a wave (shape not size). I want to get a new SPL meter anyway so I might change my system over to REW and get the RS meter.

You'll probably notice that along with the spiky artifacts it purports to be reproducing at 20Hz :rofl2:
there only 6" drivers @ $25 a piece. :no:


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