PE Cnote Bookshelf Speakers Build

Finally tuned these last weekend.

Here are the REW results: I tuned everything for about a 0.6db/oct slope downward. I tuned the sub to be that same level as both speakers playing but then added a low shelf filter as a global eq. Sub is a cheapo polk audio 10" psw110. I use the term sub loosely with this thing... This isn't a room issue. I tried it different spots and same issue with this. I guess I don't need 20-50hz....
View attachment 15252


That was pre-smaart phase aligning too.

Here are the smaart results:
View attachment 15253


The crossover is set to around 130hz. My speakers are 3' 9" from the wall which is conveniently around 80hz-100hz for them...So to get rid of that wall interference, I had to up the crossover higher than I would like. I also tried aligning the crossover region up the best which is about 100hz - 150hz when they speakers are within 10db of each other.
 
I thought I did but apparently didn't save it. I did measure it to make sure I was good and it had the best summation I could get.
 
Jdunk54nl said:
Finally tuned these last weekend.

Here are the REW results: I tuned everything for about a 0.6db/oct slope downward. I tuned the sub to be that same level as both speakers playing but then added a low shelf filter as a global eq. Sub is a cheapo polk audio 10" psw110. I use the term sub loosely with this thing... This isn't a room issue. I tried it different spots and same issue with this. I guess I don't need 20-50hz....
View attachment 15252


That was pre-smaart phase aligning too.

Here are the smaart results:
View attachment 15253


The crossover is set to around 130hz. My speakers are 3' 9" from the wall which is conveniently around 80hz-100hz for them...So to get rid of that wall interference, I had to up the crossover higher than I would like. I also tried aligning the crossover region up the best which is about 100hz - 150hz when they speakers are within 10db of each other.
Click to expand...

do you have all pass filters available in your dsp? If so you can make a way better job of that crossover, the sub has too much delay on it also, flip the phase and it should be a whole lot nicer through the crossover
 
Ya I do have all pass somewhere in it. It is an adau 1701 chip ran by sigma studio (Dayton Audio DSP-K). It has everything.

The sub has 0 delay set in the dsp, but on smart it was like 38ms to "Track" it. The other speakers were around 3.5ms to "track" them and I added as much delay as I could without running out of RAM on the dsp chip (500 samples which I am not sure on how many ms that is, but Justin showed me how I can do that). I can't add that much delay.

I also need to do some more tests. This is where I am practicing my smaart skills as it is easier to set everything up in an office compared to my truck :).

Edit* just swtiched to ms instead of samples on the program and left is delayed 12.1042ms and right is delayed 11.6667 ms. Man sigma studio is precise.... I can change the time delay by .0001 ms.
 
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Jdunk54nl said:
Ya I do have all pass somewhere in it. It is an adau 1701 chip ran by sigma studio (Dayton Audio DSP-K). It has everything.

The sub has 0 delay set in the dsp, but on smart it was like 38ms to "Track" it. The other speakers were around 3.5ms to "track" them and I added as much delay as I could without running out of RAM on the dsp chip (500 samples which I am not sure on how many ms that is, but Justin showed me how I can do that). I can't add that much delay.

I also need to do some more tests. This is where I am practicing my smaart skills as it is easier to set everything up in an office compared to my truck :).

Edit* just swtiched to ms instead of samples on the program and left is delayed 12.1042ms and right is delayed 11.6667 ms. Man sigma studio is precise.... I can change the time delay by .0001 ms.
Click to expand...

how do you mean track it? You didn’t use different delay locator settings for both drivers or try and match them using the delay locator? It will lock on the peak of the high freqs impulse response, so it does work for similar drivers like mids and tweeters, but a sub vs main alignment I would t use it for... I’d swap the polarity of the sub using a fixed delay inserted and then use the same delay inserted to time the main speakers to it, also use a 2nd order all pass on the sub at 200ish hz with a high q to better align the phase through the crossover after that

it sounds like the mic wasn’t perfectly between the speakers of the delay is slightly different, I must admit if I’m doing a pair of speakers I will measure/move/measure/move the mic until the phase overlays with equal delay if I am setting them up for a centred listening position as a best listening position
 
I tracked/find delay via smaart with the far right speaker and used that number for the rest. I would add time or subtract time in smaart until I could get the best alignment. Then find the difference in the smaart time and appropriately put that into the dsp and check it to make sure.

I tried flipping polarity on the sub but will try it again. Right now it definitely sounds better but can be even better with some more knowledge, so I appreciate the help. If I can get these nailed, then using it on my vehicles will be easier.

I just can’t believe the sub is like 35ms delayed...I expect a little beyond the other, just didn’t expect that. The Dayton amp that is on it must have a lot of delay for some reason...
 
I would start by equing/adjusting the crossovers a little for the two sides to a correct acoustical response for 24db slopes linkwitz Riley with a 150hz crossover point, then see what the phase looks like

if you look at the origin of the subs and tops you can see they are out of phase

you don’t have 35msec of delay on the sub as such, it’s the phase characteristics of the driver/box

i suspect correcting the acoustic responses will make it look smoother, then inverting the phase will allow you to add some delay to the satellites, but take some off the delay finder delay to make it all level again in the display
 
So flipped polarity and delayed the right and left by about 15.5 ms, which is about my max before my dsp runs out of RAM. The +/- 10db interaction between the sub and the speakers is about 75hz to about 130hz. That was my area that I was most interested in, but got it pretty dang close up until the sub coherence dropped drastically due to output.


@dumdum. thanks for the suggestion on flipping the polarity, this allowed for both slopes of the phase and the value of phase to be lined up pretty well!

This was also a great resource: https://www.merlijnvanveen.nl/en/st...gnment-the-foolproof-relative-absolute-method
View attachment 15265



This was the end results: NOTE THESE MEASUREMENTS WERE TAKEN AT ONE SINGLE POSITION WHERE AS THE ABOVE REW MEASUREMENTS WERE USING MOVING MIC METHOD (MMM). I also did not confirm my mic calibration file was loaded this time.

The red is no sub, the green is sub without global low shelf filter, and the blue is low shelf filter at 100hz.

View attachment 15267
 
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Finally set these speakers up in their place where the original plan was supposed to take them, my classroom. Now all the sound sounds like it is coming directly from that timer on the middle of the desk.


View attachment 16121View attachment 16118View attachment 16119

Note, above two measurements are moving mic measurments. The below measurement is a single point in space, you can see the microphone tip in the first picture, that is the point. I am getting about a 5db average summation across the frequencies too.


View attachment 16120
 
Thinking about getting this for my desktop. Did you happen to look at the Carmody S2000 as well? I'm unsure whether to stick with the smaller S2000 or get the C Note. I kinda like the plywood construction of the S2000.
 
I did not, my goal was to build the cheapest ones I could, and the c-note was it. I was looking at doing this project for an after school club prior to covid and wanted a cheap solution that allowed students to still basically build a speaker.
 
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