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PostPosted: Sun Feb 26, 2017 4:54 pm 
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Joined: Sun Sep 25, 2016 6:21 pm
Posts: 65
I am glad you are entertained, I am learning a lot, I admit that I hate just being told to trust the design I like to hear the how and why too, I appreciate the support and input of everyone who comments. Thank you all!!!

I do have a question I would like to pose that I am interested to see what I get back. I believe that as I mess with my driverack the crossover in particular I believe that adjusting the filter order or slope of one filter that the phase alligmnet changes! I find my self having to change polarity often after adjusting the filter slope or order in order to get the drivers back in coincidence. Am I crazy or is this a thing? Thank you guys in advance! :noob:


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PostPosted: Sun Feb 26, 2017 6:28 pm 
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Joined: Mon Nov 28, 2011 11:12 am
Posts: 5522
Location: Ilfracombe Queensland Australia
ACUA wrote:
I am glad you are entertained, I am learning a lot, I admit that I hate just being told to trust the design I like to hear the how and why too, I appreciate the support and input of everyone who comments. Thank you all!!!

I do have a question I would like to pose that I am interested to see what I get back. I believe that as I mess with my driverack the crossover in particular I believe that adjusting the filter order or slope of one filter that the phase alligmnet changes! I find my self having to change polarity often after adjusting the filter slope or order in order to get the drivers back in coincidence. Am I crazy or is this a thing? Thank you guys in advance! :noob:


Regarding your driverack and changing settings:
What you are experiencing is no surprise.
Phase is frequency dependant.
So when you change the frequency of the crossover point, you should expect a change in phase, leading to the correction you have noticed.
Then add in altering slope (and slope type). Since slopes are X dB/octave, they affect phase in the frequencies around the crossover point as well.

It's beyond most of us as small time operators to afford (or justify buying) the measuring equipment to test phase.
That's why, the best advice usually seen here, and the simplest thing to do, is to make sure the subs and tops/mains are in phase at the crossover point, every time you setup.
If you have phase altering capability in your DSP, then you can see if either the subs or tops are out of phase with each other at the crossover point by phase shifting by 180 degrees, and if it was out of phase, it will now get louder at the crossover frequency.
You can also make up a phase test speaker lead (it should be marked as that btw), with one plug on the lead having polarity swapped to do the same thing...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Sun Feb 26, 2017 9:14 pm 
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Joined: Wed Mar 25, 2009 7:07 pm
Posts: 1236
Location: Medicine Hat, Alberta, Canada
ACUA wrote:
I believe that adjusting the filter order or slope of one filter that the phase alligmnet changes! I find my self having to change polarity often after adjusting the filter slope or order in order to get the drivers back in coincidence. Am I crazy or is this a thing? Thank you guys in advance! :noob:


That is a thing. Crossovers affect the phase and different types and slopes all change the phase differently. If one alignment doesn't sound right then switching to another can have a huge difference as sometimes even if you align the phase together between the tops and subs at 100 hz, they may still cancel slightly higher or lower, say 150hz or 75hz as phase varies with frequency. EQ also changes the phase so after a tuning session you may also want to check your alignment.

_________________
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience


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PostPosted: Mon Apr 03, 2017 1:31 pm 
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Joined: Sun Sep 25, 2016 6:21 pm
Posts: 65
so update time i suppose, I just ordered the driver, cable and parts for a second Tuba45 cabinet, in a bit i will be picking up the wood and adhesive for the build, i am excited to add a second cabinet to the system,

I have been studying EAW's youtube videos, there is a lot of good information to be had there. i noticed a direct correlation between many of the high frequency driver configurations used by EAW and the melded tweeter array employed in Bill's designs, there is what i consider some pretty clear explanation of the science behind that array layout configured and it helped paint the picture better for me.

i will say i have been somewhat skeptical of the melded array configuration up to this point, but based off of what i am learning I am appreciating the design more and more. I am expecting people to chime in with the whole trust the design they are amazing and perfect and any modification will only yield negative results, someone will say something i am sure, i just wanted to give credit i suppose as I am more fully valuing the designs. where i am coming from is that i like to figure things out my self and not just follow instructions. I initially planed to steer clear of the melded tweeter array because I am much more used to compression drivers, I am starting to change my mind.

my next few thoughts: what is your take on coaxial configurations, like for say the omnitops, would not a coaxial configuration in an omnitop yield a good result?,
someone said that you cant biamp a melded peizo array, why not? and is there not a timing issue with the low/mid driver to the high frequency array because of how far in front the melded array sits in the cabinet? just some of my thoughts.


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PostPosted: Mon Apr 03, 2017 3:13 pm 
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Joined: Mon Nov 28, 2011 11:12 am
Posts: 5522
Location: Ilfracombe Queensland Australia
In Otops, the horn increases sensitivity of the mid driver.
In order for the HF to keep up, you need more than a coax can deliver.

Also, for those drivers that accept screw on CD's, there's not enough depth in the cab for them to fit.

As far as the piezo's and bi-amping, IIRC it's about piezo's being resistive but not inductive loads, which produces clicking.

The issue of "timing" exists in any cab design with at least two lots of drivers, and is further complicated by phase response and frequency. It's up to the cab designer to understand all those concepts, and address them at the design stage...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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