DIY Waveguide loudspeaker kit - Page 200 - diyAudio
Go Back   Home > Forums > Commercial Sector > Manufacturers > GedLee

GedLee Home of the renown Geddes Loudspeakers

Reply
 
Thread Tools Search this Thread
Old 16th August 2011, 02:49 PM   #1991
diyAudio Member
 
paulspencer's Avatar
 
Join Date: Sep 2003
Location: Melbourne, Australia
Allen, I have a draft version of all 3 parts, part 2 is coming out soon and I have to get cracking on it!

Regarding the "plastic" ... there is plastic and there is plastic. There is plastic, then there is MDF, then there is ply, then there is polyurethane! Going up in both performance and cost. I suspect you will find the two "plastics" are worlds apart.
  Reply With Quote
Old 16th August 2011, 03:30 PM   #1992
gedlee is offline gedlee  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Novi, Michigan
You need to understand that injection molded ABS and what I do are completely different things. With ABS the wall thickness is very limited, 1/4" is very thick (and very hard to do). My panels are 3/4" on the sides, 1" on the back and 1.25" on the baffle - all this is then heavily braced. The waveguide varies continuously, but is never less than 2" thick. The two methods of construction are not even remotely comparable. ABS is not at all damped and my polyurethane is extremely well damped (mine is a composite for just this reason.)

All of the injection molded ABS speakers that I have see are complete junk. Not even worth considering.
  Reply With Quote
Old 17th August 2011, 07:33 PM   #1993
diyAudio Member
 
Join Date: Apr 2011
Default Foam boards

This company in California manufactures the foam boards: Machineable Plastic, Resin, Casting Molds, and Fillers - Cedar Ridge, California They have various densities and can cut custom thicknesses. I found them very helpful on the phone.
  Reply With Quote
Old 21st August 2011, 05:03 PM   #1994
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by gedlee View Post
You need to understand
Tring to understand what your work was about, i've searched on google. Seen a lot of your presence on a lot of forums. But nowhere any real response curve, distortion curve etc... (yours looks kind a strange)

Somewhere, i've read that you do not want even to send your systems to reviews. So, sorry to be rude, and, please, apologize, but all that looks a little like snake oil, don't you think ?

Last edited by Esperado; 21st August 2011 at 05:09 PM.
  Reply With Quote
Old 21st August 2011, 05:33 PM   #1995
soongsc is online now soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
I think each designer have their own views. Earl has some good points, and not all experience can be fully and contiguously conveyed in forums where everyone is expression an opinion now and then. Also there are few reviews that are really in sufficient detail to allow people to know what the reviewer really hears.
__________________
Hear the real thing!
  Reply With Quote
Old 21st August 2011, 05:45 PM   #1996
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by soongsc View Post
Also there are few reviews that are really in sufficient detail to allow people to know what the reviewer really hears.
As an old sound designer, i've seen a lot of that kind of reviews from a lot so calling "revolutionary" systems during my (not so) long life. I remember one so calling using the enclosure resonances as controled complimentary emission. With the same kind of listening commentaries.That i know for sure, is that all serious manufacturers or designers publish their datas.
I'm pretty involved with horns design, and had made a lot of calculations on spherical waves to design horns. and a lot of measurements, so would be interested by those... if it is serious.
I would like to see the response curve of the motor, it impedance curve with no charge, it impedance curve with the horn, response curves that are not outrageously smoothed etc.
  Reply With Quote
Old 21st August 2011, 06:06 PM   #1997
Banned
 
Join Date: May 2008
Location: Switzerland
Quote:
Originally Posted by Esperado View Post
Tring to understand what your work was about, i've searched on google. Seen a lot of your presence on a lot of forums. But nowhere any real response curve, distortion curve etc... (yours looks kind a strange)

Somewhere, i've read that you do not want even to send your systems to reviews. So, sorry to be rude, and, please, apologize, but all that looks a little like snake oil, don't you think ?
Did you read any of the pages on Earl's website?
  Reply With Quote
Old 21st August 2011, 07:13 PM   #1998
diyAudio Member
 
Patrick Bateman's Avatar
 
Join Date: Oct 2006
Location: San Diego
Quote:
Originally Posted by Esperado View Post
Tring to understand what your work was about, i've searched on google. Seen a lot of your presence on a lot of forums. But nowhere any real response curve, distortion curve etc... (yours looks kind a strange)

Somewhere, i've read that you do not want even to send your systems to reviews. So, sorry to be rude, and, please, apologize, but all that looks a little like snake oil, don't you think ?
Dr Geddes has posted frequency response, polar response, and invested thousands of hours explaining why he made the design choices he made.

On his own web site he lists the names of the drivers he uses.

Hell, he's published the CROSSOVER. That's unheard of, particularly in an industry where manufacturers routinely use smokescreens and nonsensical claims to obscure the merits of their products.

I've been building horns for about fifteen years. Despite my deep investment in learning how they work, I came to the realization that I simply couldn't make a speaker as well as he could. And then I bought his.

That was a great choice, and I've been a vocal and happy customer for three years now.
  Reply With Quote
Old 21st August 2011, 07:15 PM   #1999
gedlee is offline gedlee  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by Esperado View Post
Tring to understand what your work was about, i've searched on google. Seen a lot of your presence on a lot of forums. But nowhere any real response curve, distortion curve etc... (yours looks kind a strange)

Somewhere, i've read that you do not want even to send your systems to reviews. So, sorry to be rude, and, please, apologize, but all that looks a little like snake oil, don't you think ?
I post a lot of data as Markus has highlighted. Far more than the norm, there is no "snake oil" here, I assure you. You may not understand my data presentation, that's quite possible, its not that common, but when you come to understand it you will understand why I present the data this way and not as others do it. I swear by measurements, but you have to take the right measurements.

THD or IMD or any distortion measure that I know of have never been shown to relate to sound quality in any way. Quite the contrary, they have been shown to be rather meaningless. So what would be the point in taking that data and showing it?

I do not send my speakers out for reviews, and I most likely never will. I do, and have, invited anyone, reviewer or not, to visit my showroom and listen and there are numerous reviews of this posted on my site. Setting up a truely supreme set of speakers is not easy and I simply don't trust reviewers to do it right. And you also must not be aware of the review process in this business. It has nothing to do with obtaining accurate reviews.

Trust satisfied customers - they spent a lot of money and have invested a lot of time in listening. I would be happy to put you in touch with any nuimber of satisfied (indeed elated) customers so that you can obtain some accurate "reviews".

It is indeed a sign of the times when you suspect probably the only really honest and transparent loudspeaker manufacturer out there as the one selling the "snake oil".

Last edited by gedlee; 21st August 2011 at 07:18 PM.
  Reply With Quote
Old 22nd August 2011, 01:33 AM   #2000
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by gedlee View Post
It is indeed a sign of the times when you suspect probably the only really honest and transparent loudspeaker manufacturer out there as the one selling the "snake oil".
Did-you mean that all those old manufacturers like Altec, JBL, Klipsh, Audax, Celestion etc that have bought so much in our knowledges (including your, i suppose) are or where not honest and transparent, publishing their formulas, and explaining their researches and the principle the lie to ?

I have read your white paper (difficult, because English is not my language). I agree on several points. Yes,when you build a two way system you have to take care that the directivity pattern is the same between the 2 transducers at the crossover frequency. And, by the way, it conduct often the horn to have the same diameter than the bass loudspeaker. (That's the way my personal enclosures are designed).

But you do not take care of the vertical patterns? They will have the same effects on local resonances than the horizontal ones, with the same kind of curves you shows (fig 5), because of the vertical distance between the speakers. That is not so important as it is just a question of global energy, don't you think ?. Where i use 24db/oct filters in order to minimize them, limiting the bandwidth they radiate simultaneously, you use very slow cut off The two transducers will radiate simultaneously on a huge bandwidth, with all the phase problems and accidents between us..

About your horn, i don't find anything precise about, but the form is very strange. I was mostly interested with this. My horn were calculated (around year 1990) on spheric waves and seem not to present the same profile than yours.
MHP (la Maison du Haut-Parleur) : concepteur français de kits d'enceintes pour la HI-FI et le Home Cinéma...
That is kind a strange for me. In fact, my horn present a constant directivity, with a flat curve even at 30°. So do not see what is new in your.system.
I have to add that we corrected the motional impedance of our loudspeakers, as well as Zobel, for it present a flat impedance curve. Not your enclosure, if i can see how minimal is your filter.

The last point, witch is very important for me is the vertical alignment of the speakers, in order to get phase coherency (group delay) I had not find anything about this aspect.
That's where digital filtering is a nice tool as you can work to a good and linear group delay, event is the transducers don't have an ideal vertical alignment.

This said, i have no reason to doubt (or to believe) your enclosures sound very well, that is the the way you present the things who had surprised me.
And, because i have no way to listen to them, why would i have to read and believe "reviews" of customers.I believe in measurements both with my ears. And you interesting, but strange way to present some datas does not facilitate their interpretations.

I did not and do not want to be disagreeable. Just , in the case you are a sincere and passionated manufacturer to gives-you a feed back of the feeling some prople like me can have, reading your web site. If it can help.

Last edited by Esperado; 22nd August 2011 at 01:41 AM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 12:47 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2