|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
204.87.188.80
In Reply to: www.quarter-wave.com posted by V on January 30, 2007 at 18:54:53:
HiHey, thanks for the link.
Actually I think had run across Martin about 10 years ago on the old Bass List forum.
It is cool to see he has been very busy, I will look through his stuff as I have time.
Thanks again,
Follow Ups:
Hi Tom - - I'm going to guess that Martin did not try to model such an arrangement until requests arose from curiosity in your tapped horns & white paper plus re-interest in Jensen's transflex. Cowan's attempts at TD-style T-H look interesting - two plyed ok - one had a pretty big hole.Willian's Pages
Hi FreddyiHuh, another fellow who’s been busy making sawdust.
I remember him from when Nick was selling the horns, his boxes turned out nice.
One may notice on his curves that moving the driver position AND / OR changing its parameters can have a similar effect on the response curve.
What he cannot see is the effect this also has on excursion for a give output.
It’s hard to make one by trial and error but he has gotten some good results.
Best,
For several years, Martin has been proposing driver offset in the line specifically to cancel standing wave nodes. That's part of the design process for him, and is outlined in his papers.
Back in the late 80's I was building gently tapered lines with not one but two offset woofers, with the midpoint between the woofers approximately 1/3 of the effective distance from the closed end of the line. I was trying to smooth out the sound coming from the end of a relatively unstuffed line so that the peaks & dips weren't so huge. I wrote an article about it to submit to SpeakerBuilder, but then decided to keep the idea to myself and use it in a commercial loudspeaker venture (which subsequently got derailed by my divorce).I've since gone over to vented enclosures because they enable me to use woofers whose characteristics are in my opinion better suited for good midrange reproduction.
The system described in my unsubmitted article had another trick or two up its sleeve, which I'm still hoping to one day revisit and possibly use in a commercial speaker system.
thanks V - its obvious I've not used nor studied MJK's sheets - for some reason I want a karlson-coupler to "be something" (other than bizarre toy of past) - hahaha - at regular aspect k have coupled-cavity feature with possible peak before going into a dip (3rd Z peak = 235 on K12/155 on K15), tone chamber effect (kind of slap-echo effect in upper half of coupler when fingers are snapped in the coupler) - k might only have limted use at best.those horn traps are cool
Best,
Freddy
See this one, for example:"If the driver is offset to a location at approximately one third the length of a straight transmission line, the 3/4 wavelength standing wave can be totally supressed. In fact, the impact from every other quarter wavelength mode (3/4, 7/4, 11/4, ...) will be essentially removed from the system SPL response."
(3rd try to reply) - thank you very much. Hopefully AJ-HOrn will be able to do (for simulation fun) similar work. If not then still will be fun for 'half-horn'
Good chatting with you.
Hi VBack at Servodrive / Sound Physics Labs, we began selling speakers for commercial sound with the drivers tapped forward of the apex in 1999 and I later received a patent (Unity horn) for it.
I built the first Tapped bass horn about 5 years ago and have applied for a patent on it also, at Danley Sound Labs, we have been selling them as a commercial product since January 2005.
There is / was no association with Martin’s work other than the field of interest.
Do read through Martin's papers. I think you'll find yourself on terra cognita.
Yeah, that’s called a transmission line stub in Radio Antenna land.
There are a number of antenna analogues which are useful in speaker design..
Tom
You'll notice his papers were written some 5 years ago. They describe a tapered pipe - which is what a basshorn really is - and he proposes driver offset specifically to counter standing wave nodes.
While that is similar to the old Bassmaxx style horn which had a stub, it is not like the Tapped horn in that there is no stub and side B of the driver, to provide the variable source impedance the column needs, it is near (but not a fixed proportional distance from) the open end.
Tom
The tapped horn looks to be a folded tapered line made in the way Martin King proposes. Using his method, both sides of the drivers are used as radiating surfaces, just as yours is. You have folded your pathway, but the two methods look exactly the same to me. I'm confident his spreadsheets will perfectly model your tapped horn, because it uses the same principle. Study his papers closely, I think you'll feel like you're looking in the mirror.
Hi VI have not had time to look at everything there; can you point EXACTLY to what you think is the same thing and the spreadsheet which calculates it?
See this one, for example:"If the driver is offset to a location at approximately one third the length of a straight transmission line, the 3/4 wavelength standing wave can be totally supressed. In fact, the impact from every other quarter wavelength mode (3/4, 7/4, 11/4, ...) will be essentially removed from the system SPL response."
Hi VI am not clear where you think this applies, in the Tapped horn, one driver face is at the closed end (not some distance away as he proposes) and the other face is near the open end. His concern seems to be “not driving” resonances as opposed to dealing with acoustic impedances.
You said “I'm confident his spreadsheets will perfectly model your tapped horn, because it uses the same principle. Study his papers closely, I think you'll feel like you're looking in the mirror.”
This is what I wanted you to point out to me, where is "that part" of his site?
Tom
Well, you might start on the main page. The principles are fundamentally the same as what you are doing, so I think probably you'll be interested in seeing what MJK has written. I'm surprised you hadn't seen this before, since he's been pretty visible in the DIY community.
Greets!MJK said they won't in this post, has he since changed his WSs?
GM
As you can see, MJK says, "I thought about the problem yesterday and concluded that a worksheet to model this type of enclosure is possible. It would require some rearranging and extension of the math but I believe it could be done." The concept is there already, and you can see in his prior work that he was thinking along these lines. I think his work is worth mentioning in this regard, perhaps giving some credit where due.
Greets!I'm all for giving the man his due, and have on numerous occasions and nearly as many forums, but he only thought about it after being presented with the concept. Clearly, he didn't have it in mind when he was developing his WSs and after talking with him yesterday still has no plans to modify his WS to model a tapped horn or TL.
Hi VSo you can’t actually point to a Tapped horn on his site then?
MJK tends to concern himself with ideas more than specific implementations. However, the MJK analysis describes the principles used in what you are calling a tapped horn. Not to sound like a broken record, but again, I encourage you to read through his papers if you haven't already.
Hello V,It looks like you do not completely understand what a 'tapped horn' is. Offsetting the driver in a TL is a very old trick, Martin did not invent this. I think the credits for the 'roots' of the Tapped horn go to Jensen with their Transflex design.
Best regards,
Hi WaltI agree about the Transflex, the first time I saw it I thought OMG, it’s nearly a Tapped horn. In modeling the Jensen, the reason it isn’t a modern product came out though.
As you have seen, it isn’t easy to get all the relationships right as there is no written procedure to rely on.
Best,
It really is old news"Sound reproduction"
G.A. Briggs
1953
Yes, perhaps you are right. However, MJK did a very nice job of quantifying things through mathematical analysis. I think some credit is deserved by several people, Jensen, King, Danley, to name a few. By the way, I like what you've done too.
Hi VI don’t belong in “that” list.
Understand, I quit the AES 11 years ago and have not published any papers or references on the Tapped horn other than the White paper and talking about it at trade shows etc..
Other than the explanation in the white paper (which you’ll notice is not at all like Martin’s) and occasionally talking about it on forum’s, that is about it so far as public disclosure.My focus was first seeing if I could exploit “something” I saw with the Unity and Synergy horns, then on making it work well enough to be a product and then getting the most out of it.
My understanding and explanation of how it works, the path to designing them and all the design tools involved were things I derived without outside help / input.
Now, the determination of “if” this is novel is up to the Patent office to decide but the performance of the current Tapped horns compared to regular small bass horns is such that “if” someone else had made it work properly, they certainly would have used it.
Keep in mind the th-115 and th-215 are both smaller / lighter than all but one speaker model tested at a recent Pro-Sound subwoofer shoot out.
http://srforums.prosoundweb.com/index.php/mv/msg/20327/0/16/0/
http://srforums.prosoundweb.com/index.php/t/20399/0/
Arnold Klayman patent number 5, 177, 329 Arnold is 82 now and retired.
I also found another patent that came out about ten months after Klayman's, Hayakawa US # 5, 197, 103 which is similar. Then there is also patent US 4, 064, 966 worth looking at as well. Going back to 1962 you can see another similar patent US# 3. 047, 090 look at fig. # 4. Regards Moray James.
moray james
This post is made possible by the generous support of people like you and our sponsors: