|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
216.184.97.165
Wonder if the side mounting (hole exit) of the 5 1/2" drivers plays a role in this or is it just due to the necessary distance from the HF comp driver??? Does anybody know?? Does side mounting=hole exit affect MR and HF performance of the drivers??
Follow Ups:
I'm the guy that put a Unity into my Honda Accord.Here are three pages of information that will help you choose a midrange for a Unity horn:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=88237&perpage=10&pagenumber=1The thread that I started on audiogroupforum.com is something like 20 pages now.
As Tom said more elegantly than I can, there will be a reflection from the throat that will insert a notch into your response. I didn't realize this before I started my project.
For me, I found it was very challenging to get the midranges to play very high.
:: PB ::
- http://www.diyaudio.com/forums/showthread.php?s=&threadid=88237&perpage=10&pagenumber=1 (Open in New Window)
Some good info here: http://www.audiogroupforum.com/csforum/showthread.php?t=62789Yeah it's in a car, but this guy has really dug into it. These guys are every bit as obsessive as the home hi fi'ers.
Sheldon,Thanks for the kind words! I learned a lot from that project. I'd like to do it again with a conventional tweeter in a much more compact waveguide.
maybe they're lowpassed by relatively small holes (besides mids running out of steamp power-wise)
Hi Nicolas, Freddyi, allSorry for the delay.
A number of things conspire to limit the hf response of all drivers and some extra things are added with the Unity and Synergy horn drivers.
As with any horn driver, both moving mass and series inductance impose a roll off slope somewhere.
Additionally, in this configuration as the mysterious V suggested, there is a notch, which is cause by the reflected signal from the closed end of the horn.
When the frequency is high enough so that the total path equals 1 / 2 wl, there is a cancellation notch (and a pattern of cancellation notches repeating above at 180 degree intervals.
The sum of those notches alone produces a roll off of acoustic power above this F, a lumpy acoustic low pass filter..
Lastly, the trapped air volume under each cone, combined with the air mass in each connecting port, form an acoustic low pass filter as well.
These two acoustic low pass filters (unlike electrical series L which is on the pre-acoustic leg) combine to greatly attenuate the inevitable harmonic distortion present in all drivers. Many of the harmonics the driver produces, fall in the range where the low pass filter is, hence they are reduced while the fundamental level is unchanged.
Best,
Makes sense Freddyi too bad Tom is not available to comment as side mounting drivers is very useful even if not in Unity type horns.
might figure out something with cardboard & duct tape or wood mockup scooting stuff aound -- mid holes traditionally hug ~apex of horn walls' junction. response comes back up as diameter allow smaller wavelength = on this graph one octave spacing of leak-peaks (if thsts correct way to view/term?)
The limit is set by the null from the first standing wave node.
Interesting that Tom had difficulty getting "good" performance even when using only two MR drivers....which can be placed very close to apex and HF driver. Don't know details of the difficulty but first standing wave in this case should be much higher than 1K Hz.
Usually when a driver is placed some distance down the line, it's the standing wave nodes that set usable upper cutoff. However, the rest of the things that rolloff HF come into play also, so surely something like Le or mass or any number of other things can set the upper limit.
thanks
My pleasure
This post is made possible by the generous support of people like you and our sponsors: