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Tweeter Alignment Results

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Posted on August 9, 2014 at 11:19:00
jcmusic
Audiophile

Posts: 1387
Location: New Orleans, La.
Joined: June 13, 2006



This is where I ended up with the new tweeters. The red trace is the original tweeter not aligned, the darker trace is the fostex tweeters vertically aligned with the mid drivers.

 

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RE: Tweeter Alignment Results, posted on August 9, 2014 at 15:17:52
unclestu
Dealer

Posts: 5851
Joined: April 13, 2010
 Looks like a frequency response sweep which has really no indication of drivers being aligned. You need an impulse test for that.

 

RE: Tweeter Alignment Results, posted on August 9, 2014 at 21:06:15
Tre'
Industry Professional

Posts: 17305
Location: So. Cal.
Joined: February 9, 2002
 Wouldn't drivers being partially out of phase with one another do to lack of physical alignment cause frequency response abortions?

Might not be the final word but I would say it's some indication.

Of course I would want to see the FR/phase curves for each driver to help shed a little light on what the overall FR curve is telling us.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Tweeter Alignment Results, posted on August 10, 2014 at 05:42:11
Bill Fitzmaurice
Industry Professional

Posts: 5371
Location: New England
Joined: October 20, 2002
 The OPs post makes perfect sense taken in context with his previous thread. If you haven't read that, not so much.

 

RE: Tweeter Alignment Results, posted on August 10, 2014 at 07:09:59
jcmusic
Audiophile

Posts: 1387
Location: New Orleans, La.
Joined: June 13, 2006
 Thanks Bill I hadn't realized that until you pointed it out...
Anyway it looks like I may need to attenuate the tweeter or bump up the mid driver to get a better balance. I can attenuate the mid driver from my xover so not a big deal...

 

RE: Tweeter Alignment Results, posted on August 10, 2014 at 10:10:13
dlp4341
Audiophile

Posts: 26
Location: Chicago Sub No
Joined: September 17, 2007
 If you need a test signal to check your alignment, I put one on my web site. You can use any electret mic to pick up the acoustic wave and a scope to display the result.

 

RE: Tweeter Alignment Results, posted on August 10, 2014 at 21:40:30
Saturntube
Manufacturer

Posts: 331
Location: Austin
Joined: April 21, 2006
 What was the difference soundwise?

 

RE: Tweeter Alignment Results, posted on August 11, 2014 at 04:11:29
jcmusic
Audiophile

Posts: 1387
Location: New Orleans, La.
Joined: June 13, 2006
 Are you kidding??? Did you look at the two graphs??? There was a huge difference in sound quality, everything got cleared up. The soundstage opened up quite a bit and the highs are much more pronounced..

 

RE: Tweeter Alignment Results, posted on August 11, 2014 at 04:43:13
Saturntube
Manufacturer

Posts: 331
Location: Austin
Joined: April 21, 2006
 Jajaja, you dont have to convince me! Just trying to make a point.
I know how drastic the difference is...

Now, after measuring, doing all the graphs and listening experience, knowing roughly the right position: would you be able to time align by ear next time?

 

The graph response above 6 k makes no sense in just "aligning" without more info on the setup, posted on August 11, 2014 at 09:44:49
Edp
Audiophile

Posts: 4503
Joined: September 23, 1999
 I don't see how "aligning" would jack the response above 6k over the "non-aligned" configuration.

Something else is at play to get those dramatic differences. Is there another post (use optional Link URL to point to that series of posts) with more detail you could add this thread?

"EDIT" I searched on your moniker for past posts and I see you are talking about using a different tweeter in a different location between the two graphs and assume this is still based upon Klipsh Corner horns. Not certain that the differences you post in graph are not just differences in drivers instead of alignment.

 

RE: Tweeter Alignment Results, posted on August 11, 2014 at 16:26:48
jcmusic
Audiophile

Posts: 1387
Location: New Orleans, La.
Joined: June 13, 2006
 Maybe I am not sure, I would rather be exact and I like measureing electrically makes me feel better.

 

RE: Tweeter Alignment Results, posted on August 12, 2014 at 07:07:27
tomservo
Manufacturer

Posts: 8211
Joined: July 4, 2002
 Hi
Measuring is the best way to arrive at the optimal result.
If you can, get a copy of ARTA or other low cost measuring software and a half decent measurement microphone.

Fwiw, impulse response and step response are actually poor ways to judge this, the acoustic phase (phase once the fixed time delay has been accounted for) is the best view as it shows the relationship to the input signal or between the upper and lower frequency range.
The impulse and step response emphasizes the HF response portion and makes the LF hard to see.
Best,
Tom Danley
Danley Sound Labs

 

RE: Tweeter Alignment Results, posted on August 12, 2014 at 19:50:28
jcmusic
Audiophile

Posts: 1387
Location: New Orleans, La.
Joined: June 13, 2006
 Let me clear the air some, yes I am using a different tweeter that's why the huge difference in the two plots. As for alignment I used RTA with the polarity fliped on the tweeter to create a null or peak at the xover point while playing that frequency with a generator. Hope that explains it better.

 

RE: The graph response above 6 k makes no sense in just "aligning" without more info on the setup, posted on August 13, 2014 at 04:00:06
jcmusic
Audiophile

Posts: 1387
Location: New Orleans, La.
Joined: June 13, 2006
 It is both new tweeters and alignment...

 

RE: Tweeter Alignment Results, posted on August 13, 2014 at 06:14:14
tomservo
Manufacturer

Posts: 8211
Joined: July 4, 2002
 Hi
The problem with not including time (which an RTA does not) is that one will get a null (with polarity flipped) every 360 degrees of phase rotation. In other words, the measurement will have a null if you are in the correct time but also every wavelength (360 degrees of phase error) as the sources are 1,2,3 etc wavelengths either ahead or behind in time as well.
Since some music is very “time variant” and not a continuous signal, one can have what appears to be a correct alignment with an RTA but in reality be off by one or more wavelengths with one source being far ahead or behind in time.
Best,
Tom

 

RE: Tweeter Alignment Results, posted on August 13, 2014 at 08:21:54
jcmusic
Audiophile

Posts: 1387
Location: New Orleans, La.
Joined: June 13, 2006
 Thanks Tom I plan on remeasuring this weekend using impulse with a time reference.

 

RE: Tweeter Alignment Results, posted on August 24, 2014 at 15:16:22
jcmusic
Audiophile

Posts: 1387
Location: New Orleans, La.
Joined: June 13, 2006






Let me add the impulse response graphs...

 

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