AudioRoundTable.com - RDF feed
type: channel
description: Audio advice and discussions with audiophiles and professionals. Free discussion forums, open to all and frequented by industry experts. Ask questions and get advice on stereos, speakers, hi-end amplifiers, pre-amps, home theater, tube hi-fi, turntables, vinyl, tweaks, music, films, video, DVDs and more.
items: Geddes Waveguide
items: Re: Geddes Waveguide

Geddes Waveguide
type: item
description: I am intrigued by Geddes horn philosophy. Horns like this seem to be a wave of the future. Let me quote Geddes. He says, the goal is smooth constant directivity over a prescribed angle. Most CD horns use a diffraction slot to obtain polar control, however, diffraction gives rise to periodic peaks and dips in the response at all angles because of standing wave created from the wavefront reflection at the point of the diffraction. It is well known that diffraction less horns, like tractrix have superior sound quality, but they lack directivity control. The goal then is directivity control without diffraction. The holy grail would seem to be CD horns without diffraction. Maybe tractrix and other horns like it are obsolete? http://www.gedlee.com/new_loudspeaker.htm
creator: Paris
date: 2004-10-12T18:44:58-00:00

Re: Geddes Waveguide
type: item
description: hmm i dont know enough about HF horns to comment.. Read something like the jbl4430 manual -which describes DI and all sorts and says exactly why there product is good.Also many graphs and diagrams.
creator: Mike.e
date: 2004-10-13T22:56:53-00:00

Re: Geddes Waveguide
type: item
description: Has anyone ever seen this waveguide? I can't even find a verbal description anywhere. -Mark Seaton
creator: Mark Seaton
date: 2004-10-15T21:47:19-00:00

Re: Geddes Waveguide
type: item
description: There is more to my theory than simply the shape. All of this is well documented in my book or in AES papers and the like. Its not new at all, nearly twelve years old at this point.
creator: Earl Geddes
date: 2004-12-24T03:35:30-00:00

Re: Geddes Waveguide
type: item
description: Thanks for writing here. From what I gather, you don't like the dispersion of tractrix horns, and don't like response of CD horns. Is that about it? What about a combination of the two, a CD horn with a radiused edge? That's what your prototype looks like it uses. Is that what you propose, in a nutshell? http://www.gedlee.com/new_loudspeaker.htm
creator: Paris
date: 2005-01-03T11:11:08-00:00

Re: Geddes Waveguide
type: item
description: I don't think my point is that black and white, but yes, I think that things can be improved over Tratrix and CD horns. Mine are not simply classical CD horns with a radius'd edge. Its not quite that simple.
creator: Earl Geddes
date: 2005-01-03T13:59:21-00:00

Re: Geddes Waveguide
type: item
description: Would you care to elaborate? I am most interested in your design concepts and want to know more. Are your speakers for sale anywhere now? Where can they be auditioned? Thanks in advance.
creator: Paris
date: 2005-01-06T11:08:57-00:00

Re: Geddes Waveguide
type: item
description: Look at the polar response of the Geddes speaker at the link. From what I know, it uses the narrowing DI of the woofer to match the waveguide at crossover for very smooth polar response. The waveguide has constant DI, so it is EQ'd in the crossover for flat power response. Isn't that about right, Dr. Geddes? http://www.gedlee.com/waveguides.htm
creator: Paris
date: 2005-01-06T11:14:31-00:00