Sloped as in the Wilsons or Focals.
I think the benefit relates to a more consistent radiation pattern...less comb filtering...a wider sound field.
Are there links to discussion on this topic? I wonder why these and other manufacturers do this. I want to include this in my speakers if it is a genuine improvement.
I think the benefit relates to a more consistent radiation pattern...less comb filtering...a wider sound field.
Are there links to discussion on this topic? I wonder why these and other manufacturers do this. I want to include this in my speakers if it is a genuine improvement.
The Wilson Maxx is one example of a speaker with the M's sloped with respect to each other.
http://www.wilsonaudio.com/products/maxx/drawing.shtml
http://www.wilsonaudio.com/products/maxx/drawing.shtml
The tweeter waveguide project is gaining momentum. The Seas H1212 has been chosen for prototypes. Several will be made for measurements. Results of measurements will be used to do more test guides until one is found suitable to build into a speaker.
Other tweeters will be considered and results will be posted.
Thanks for your interest, Michael.
Sidenote: My selection of Wilson & JMlab are as examples only. I've only heard one of them briefly. I'd like to understand the theory and use it, possibly.
Other tweeters will be considered and results will be posted.
Thanks for your interest, Michael.
Sidenote: My selection of Wilson & JMlab are as examples only. I've only heard one of them briefly. I'd like to understand the theory and use it, possibly.
Greets!
It's about aligning their acoustic centers at the XO point to ~preserve the signal's phase response: http://www.silcom.com/~aludwig/Loudspeaker_construction.html#Time_alignment
GM
It's about aligning their acoustic centers at the XO point to ~preserve the signal's phase response: http://www.silcom.com/~aludwig/Loudspeaker_construction.html#Time_alignment
GM
GM, Thanks for the links. Both are valuable and address topics I'm interested in here. It will take awhile for me to wrap my head around them. Good stuff.
It appears that I have 2 issues (or more).
Time alignment will be affected by the depth of a waveguide. I think that is easier to understand than the second.
Manipulation of lobing to increase (broaden) the sweet spot. At this point I can only imagine it necessary to measure driver arrangements to optimize.
It appears that I have 2 issues (or more).
Time alignment will be affected by the depth of a waveguide. I think that is easier to understand than the second.
Manipulation of lobing to increase (broaden) the sweet spot. At this point I can only imagine it necessary to measure driver arrangements to optimize.
Greets!
You're welcome! Here's a bit more technical one to enlighten/confuse and addresses the MTM layout: http://www.birotechnology.com/articles/VSTWLA.html
GM
You're welcome! Here's a bit more technical one to enlighten/confuse and addresses the MTM layout: http://www.birotechnology.com/articles/VSTWLA.html
GM
Ed Lafontaine said:
Greets!
Correct on both accounts, but if the front of the VCs are vertically aligned, then a first approximation can be calc'd to account for the additional rear offset due to the XO's phase rotation: (SoS/XO frequency)/(360/XO slope). Then you can use a RTA, or even just a tone at the desired frequency and a SPL meter to 'dial it in' close enough without the need for expensive systems that can measure time delay: http://web.archive.org/web/20041111094232/http://www.soundpractices.com/images/phase.pdf
As you can see, this stuff is 'old hat' to prosound system designers, but until the wide dissemination of their knowledge on the net and the high cost of test gear only significantly falling fairly recently, the typical DIYer was either oblivious of such things or only able to ~copy some proven design, and then only if they could get enough of its specifics.
Fortunately for inquisitive folks like me and ultimately bad for them, Altec, Jensen, University, etc., ~freely distributed the bulk of their knowledge to anyone who asked. I can't think of a single Q they didn't answer to my satisfaction.
GM
Thanks GM for those greate links!
Ed, well I guess we have our heads occupied for a while now!
I thought so you had something with time alignement in mind, but with given links I don't have so much to add.
But as I mentioned in my first post also stepped baffles are used!
Looking forward to your future postings regarding your waveguide projects!
Cheers michael
Ed, well I guess we have our heads occupied for a while now!
I thought so you had something with time alignement in mind, but with given links I don't have so much to add.
But as I mentioned in my first post also stepped baffles are used!
Looking forward to your future postings regarding your waveguide projects!
Cheers michael
Let me probe with a thought just occuring to me:
The axis' of M's sloped with respect to one another converge in the near-field. In far-field they diverge. I wonder if this could be described as a (limited) circular field radiation pattern? This borrowing from pro-sound configurations.
My question that arises from this is how do I determine the proper angle?
I'm making progress wrt waveguides due to the generous offering of a corespondent to test the output from a variety of shapes. I don't have the facilities with which to test.
The axis' of M's sloped with respect to one another converge in the near-field. In far-field they diverge. I wonder if this could be described as a (limited) circular field radiation pattern? This borrowing from pro-sound configurations.
My question that arises from this is how do I determine the proper angle?
I'm making progress wrt waveguides due to the generous offering of a corespondent to test the output from a variety of shapes. I don't have the facilities with which to test.
Greets!
Yes, the object is to create a large oval point source with a wider than high polar response.
The arc's radius is to whatever the midpoint of the listening position(s), so if it's 12 ft.......... The tighter the arc though, the worse the off axis response, so a DIYer has to juggle a JM Labs' style design to find acceptable trade-offs with the desired drivers, proposed listening distance/area.
A hi-end designer OTOH can pick a focal distance and adapt the drivers to suit.
GM
Yes, the object is to create a large oval point source with a wider than high polar response.
The arc's radius is to whatever the midpoint of the listening position(s), so if it's 12 ft.......... The tighter the arc though, the worse the off axis response, so a DIYer has to juggle a JM Labs' style design to find acceptable trade-offs with the desired drivers, proposed listening distance/area.
A hi-end designer OTOH can pick a focal distance and adapt the drivers to suit.
GM
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