Another thing that was not mentioned.
At these short wavelengths it is easily possible to be "in phase" but of of time alignment. You could be in phase, but at a distance of several wavelengths!
So using pulse measurement would be the best way to time align. There is plenty of software and some hardware that can help with this.
At these short wavelengths it is easily possible to be "in phase" but of of time alignment. You could be in phase, but at a distance of several wavelengths!
So using pulse measurement would be the best way to time align. There is plenty of software and some hardware that can help with this.
The simplest way would be to build a first order XO, run some frequency responses with the mic at the listening location while shifting the supertweeter untill the notch in the FR flattens out. If you move the supertweeter in a direction and find that the notch lowers in frequency, then move it the other direction.
soongsc said:
Do you mean if the notch deepens in amplitude?
The notch frequency shouldn't change, right? Or am I missing something?
If you are looking for dips in F.R. to align, that will work - but how do you know you are within a 1/2 wavelength? You could be 4 or 5 wavelengths out of time, but still be in phase. That wouldn't happen using a pulse test.
Using the frequency response null for low frequncies is much easier - e.g. aligning mid to woofer, because the wavelengths can be much longer than the cabinet. 200Hz = 67 inches. Pretty hard to be off be a full wavelength there!
CPORADA- have you had any luck so far?
panomaniac said:
Do you mean if the notch deepens in amplitude?
The notch frequency shouldn't change, right? Or am I missing something?
If you are looking for dips in F.R. to align, that will work - but how do you know you are within a 1/2 wavelength? You could be 4 or 5 wavelengths out of time, but still be in phase. That wouldn't happen using a pulse test.
Using the frequency response null for low frequncies is much easier - e.g. aligning mid to woofer, because the wavelengths can be much longer than the cabinet. 200Hz = 67 inches. Pretty hard to be off be a full wavelength there!
CPORADA- have you had any luck so far?
Lobbing effects will change, and yes, the notch will go away eventually. If it's easier for one to sway the mic up and down, you can also do so till you find the point where the notch would either go away or will move in a different frequency direction each way you sway the mic. Find the mic location for the best notch, then recalculate the location of the ST for your listening location. Rerun the test to fine tune.
I don't think you can measure good low frequencies in a room.
I have had a good deal of luck thus far. The intial crossover was way too low. After a couple of weeks, things went from sounding really exciting to sounding somewhat fatiguing. I removed the 1.1uF caps and replaced them with two 0.22uF North Creek caps and a 0.01uF Infinicap bypass (0.45uF total), which, according to the crossover webpage I found, should have me at -3db at somewhere around 39kHz, but with such a gradual slope that there is still some very high frequency audible information coming through, i.e., if I listen to test tones, I can hear some of the highest tones up near 20kHz coming from the supertweeter. The sound now is much better, and not at all fatiguing, just a hint more "sparkle" and much better resolution of microdynamics and very subtle details in the music. The SACD of Pink Floyd's DSOTM is unbelievable now on the tracks that involve symbols/high hats. It sounds like the drum set is right in the room. I still haven;t figured out how to get the precise alignment, though. All of you have made great suggestions, but I don;t have any type of equipment. I've just tried to align it with the tweeter on the main speakers by eye, and angled it down to my listening position using a laser pointer. Any suggestions on how to get time-alignment without fancy equipment would be great if that's possible.
Thanks for all the help
Chris
Thanks for all the help
Chris
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