 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
71.127.74.27
In Reply to: RE: Olsen Modified BLH monster posted by Paul Eizik on June 22, 2007 at 10:20:30
Paul,
Now you've done it! John's a goner.
Headlines: Massive Horn stack swallows Melbourne! Sydney next?
Eizik syndrome rumored.
Nice to see an old design reconstructed.
How does the this design work? Is it a dual chamber with reflex characteristics for the top half somehow tuned and coupled to a further horn expansion? Impedance plot might show.
Good luck on the remodel.
Tim
Follow Ups:
Hi Tim,
I think the enclosure functions basically as a back loaded horn. An exponential expansion is approximated in the series of sections with increasing width plus the continued expansion through the path down below. The chamber behind the driver probably works as a low pass filter. There was further filtering in the original Olson design from restrictions placed in the horn path.
Hi Steve,
Thanks for the response.
This is the first time I've seen a design such as this with a deliberate impediment to a continuous flare. Very interesting.
I guess my assumption has always been that numerous pathway bends would also provide the low pass function, without further need to create a port/aperture midway through the expansion and risk a reflection/response hiccup. "One never interferes with or deliberately obstructs the flare rate" kind of mentality at work here, you understand.
I would also assume that Olson would never publish a design that would contain any major flaw without explanation, and that the reflection is either non-existent or reduced to the inaudible through the combination of tuning devices provided.
In any case, a really neat project.
Tim
Tim
It's easy to follow the logic of not interfering with, or impeding the flare rate. Ben Rich, in his book "The Skunkworks", told the story of discussing the conical spikes in the intakes of the SR71 engines with a general once. The general said "I would think that the idea would be to get as much air in as possible" and Rich replied "Did'nt you ever put your finger over the end of a garden hose when you were a kid?". The restricted throat of a BLH is usually looked at as a necessary evil to balance the output of the horn and direct radiator, but compression mid driver designers use this all the time. The mid has a compression ratio and frequently a phase plug too to squeeze more bandwidth out of the driver. As to reflections coming from the aperture at the end of the manifold in the Olson BLH, these reflections have to pass back through the muffler effect of the manifold (against the "current" of the sounds tendency to flow from a high pressure area to a lower), and also through the low pass effect of the first air chamber before they could get to the cone and pass through it to cause any mischief in the output of the direct radiator.
Finding a major flaw in Olson's work? Yeah, I wish! I'd be off to the patent office in a jiffy ; )
Paul
Hi Tim
I've long felt that participation on this forum would serve one well when trying to cop an insanity plea. Lawyer: "Your honor, my client is clearly not in control of his imagination, and could hardly create a $300 clock radio which could seriously compete with the Bose company..." Ya never know when something will come in handy...
Your question as to how it works came up while looking into Olson's patent for this project. Olson attached some importance to the chambers and coupling apertures. A BLH probably has more room for adjustment here (as opposed to a double loader) due to the fact that the horn output has to be attenuated anyway to match the direct radiator output. I can't wait to try some of this out an my rig (which is buried behind a wall of piled up furniture now). It will be interesting to see if some bass extension is possible (probably at the expense of some bass output). An impedance plot will be interesting too, something I have spent little attention on previously. Great idea!
Thanks for your idea and well wishes as I go back down to the mine.
Paul
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
