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Get familiar with the reaction system: Introducing the Reaction System
Cx120 build
in DIY
I got a pair of Cx120 from JR and they will be my first attempt at designing a speaker.
Box is 2.86L. Tuned to 76hz, f3 modeled to 72hz.
I did not have a 1 5/16" bit to drill the holes for the pvc.
Just got a motu m2 and a soundid mic for 2 channel measuring. This will be fun and frustrating for sure.
Comments
Loudspeaker parameters:
Fs = 87.57 Hz
Re = 6.20 ohm[dc]
Le = 166.62 uH
L2 = 256.05 uH
R2 = 8.39 ohm
Qt = 0.45
Qes = 0.54
Qms = 2.73
Mms = 6.67 grams
Rms = 1.350332 kg/s
Cms = 0.494882 mm/N
Vas = 2.13 liters
Sd= 55.42 cm^2
Bl = 6.499366 Tm
ETA = 0.26 %
Lp(2.83V/1m) = 87.29 dB
Ports are in.
One glued up and the other in process.
Now I need to flush trim, chamfer and sand. Will figure the finish later.
Looking good. You're almost to the best part - plugging them in to see how they sound!
Looking great! Just please use black screws
Could not find in Lowes or HD, so, will have to wait until I order xo parts from PE and add screws.
First will need to measure... This time will be a long road.
BTW, what level do you measure at? 1V? 2.83V?
I always measure the tweeter first and slowly crank up the volume until I feel the tweeter can't take anymore power without considerable distortion. Then that is the volume I measure everything else at. Hope that makes sense.
If you are using stainless screws, you can hit them with a torch and they will turn a nice shade of blue'ish. If they are the zinc coated kind of skrew, they will turn grey and then you can hit them with a marker, or paint pen, and the color will hold.
Do you have a Menards or Ace hardware near you? They have a much better selection on hardware.
Will check if one is close.
Other than the router walking on me, I'm ready to start measuring.
Just do that three more times and it'll be a "design feature" 👍🏼
Quick and dirty on axis.
Lol that's how most of my "unique" design choices occur! Lemons->Lemonade
Today I got to measure this form 0 to 180 in 11.25 degrees increments. Far at about 1m and nearfield.
Now I'm trying to merge in Vituixcad, but no idea if this looks good:
Well, I'll need to redo all, will be fun.
Is the red under the white line? If so it looks fine to me.
It is a bit below, the impulse are dirty due to mismatch between arta and windows settings (44100 in windows vs 88200 in arta).
So, I'll need to measure again.
The tweeters do not agree one with another...
Man, that sucks!! Dayton and their QC problems with tweeters strikes again!
I think that is a tweeter placement issue, as in the depth front to back. I've found the pole piece in most Dayton woofers aren't machined on the end so there is some difference in length. I had a similar response difference with the Minion build. I had to sort through a pile of copper washers in order to get the two tweeters shimmed out the same and get matching responses.
Mmm, might try to play around, to my crappy eyes they look the same.
A few thousandths can make a sizable difference.
This is about 6 thousandths difference.
That is not minimal...
Red trace up or down compared to the black?
It would be interesting to run the woofer ~fs through 400Hz (pink noise?) one channel and the tw through (other channel) its frequency range (sweep) to look at impact of the 'moving baffle' on the tw
If I remember correctly the black trace was forward, out in front of the cone.