While I do like it here, what I do is not DIY. I will be starting my own forum very shortly as this is the only way that I can talk frankly about my philosophy without it being taken as an advertisement (a very common complaint if you havn't noticed). I do advertise here (its about the only place that I do) and I will continue because this site is one of the better ones and I'd like to support it. But I can't deny that I don't belong here any longer.
Probably so, but thats not my interest. I have done audio all my life and I want to pass on what I have learned. (Can't teach it, that's not possible!) I think that the audio community could benefit greatly from the knowledge that I have gained. I am not really into it for the money actually (contrary to popular belief). Compared to past salaries that I have had, or my current consulting rate, making speakers is chump change. But still, I am not about to take a loss or not get paid for my time. That would just be stupid.
@ Keyser
Did you ever consider using a closed panel at the back? And maybe even close the sides at the back of the speaker?
Example: http://www.luxury-insider.com/luxury-news/2008/06/amphione28099s-krypton-2-speakers-for-true-audiophiles
This will of course cause more internal reflections, but before the wave gets back to the front (to do something wrong), it will need to pass through twice as much damping material.
Advantage would be that the radiation pattern of the bass-mid is even more equal to that of the horn (no rear/side radiation)...
Did you ever consider using a closed panel at the back? And maybe even close the sides at the back of the speaker?
Example: http://www.luxury-insider.com/luxury-news/2008/06/amphione28099s-krypton-2-speakers-for-true-audiophiles
This will of course cause more internal reflections, but before the wave gets back to the front (to do something wrong), it will need to pass through twice as much damping material.
Advantage would be that the radiation pattern of the bass-mid is even more equal to that of the horn (no rear/side radiation)...
To be perfectly honest Gedlee I dont agree. You do belong here. Im sure many people here have made someone some speakers, maybe several. Maybe even sold some. I havent, and there are also just as many that havent either. Its a lifestyle business, and for that reason I think your 'philosophy' for want of a better word, since its more than that, Is welcome. I actually think its open discussion promotes your product well, since few manufacturers share ANYTHING, especially smaller high end producers. That i think shows integrity, and without being patronising; not everyone will agree, many will, many may not fully understand, and there are the malicious kind. Some may just disagree, but not entirely know why. But the customers you want, are the ones you have, and sure as eggs are eggs being here, and sharing a little has helped find your market.
Honest to goodness, if it wasn't for Dr. Geddes, I'd still be wondering "what's wrong with my cone and dome 2-way?" and "what's wrong with my quacking horns?(ha ha)" I'm sure there are many the world over with this same position. Not everyone will like what anyone says, but what Dr. Geddes says people read and consider carefully. I bet Dr. Toole would have sold very few books for that matter w/o your public commentary and thus a fundamental knowledge of acoustics and psychoacostics for sound reproduction has improved radically in the last few years on some boards.
I'd venture to say this very speaker and thread would likely never happened without your prior input/philosophy.
just my opinion,
Dan
I'd venture to say this very speaker and thread would likely never happened without your prior input/philosophy.
just my opinion,
Dan
We're going OT here (this topic deserves its own thread), but I think a DIY'er is a tough consumer to sell something to. We like to build our own speakers and if we are going to buy a speaker made by someone else, it better be very good and not too much more expensive than if we were to build something similar ourselves. On the other hand, if you are selling a technically superior product, how do you explain its superiority to customers who know nothing about loudspeakers and (psycho-)acoustics - i.e. the typical audio nut?
Could any of the moderators please split this part of the discussion off?
Could any of the moderators please split this part of the discussion off?
Keyser
I have no problem splitting this discussion off, thats fine, but you were the one who asked me to come here because people were discussing my speakers. Well they say a lot of things that aren't true, so I corrected the record.
I am a little touchy about this because I was recently banned from a major audio site for exactly this same thing - someone asked me to go to a thread where I corrected some misinformation and I got booted for "adverstising". OK, I'll go somewhere else.
As I said, I like it here and I'd just as soon not get the boot here as well. So I do have to limit my discussions.
Ask yourself - how can Geddes seperate what he believes and preaches from what he sells? Is that even possible? If its not then he simply cannot respond to anything without the accusation that he is being commercial. Its an impossible situation.
I have no problem splitting this discussion off, thats fine, but you were the one who asked me to come here because people were discussing my speakers. Well they say a lot of things that aren't true, so I corrected the record.
I am a little touchy about this because I was recently banned from a major audio site for exactly this same thing - someone asked me to go to a thread where I corrected some misinformation and I got booted for "adverstising". OK, I'll go somewhere else.
As I said, I like it here and I'd just as soon not get the boot here as well. So I do have to limit my discussions.
Ask yourself - how can Geddes seperate what he believes and preaches from what he sells? Is that even possible? If its not then he simply cannot respond to anything without the accusation that he is being commercial. Its an impossible situation.
I think there are members of this forum that can not stand others to have commercial associations and take part at this forum.
I think when one understand the subject he can make the choice if it is commercial related or subject related information. So in this respect I do not see big problems when people do invest in understanding the discussed subject.
And than it is easy to make your own right decisions.
I think when one understand the subject he can make the choice if it is commercial related or subject related information. So in this respect I do not see big problems when people do invest in understanding the discussed subject.
And than it is easy to make your own right decisions.
.
If a correct tonal reproduction is a design goal then:
a) a flat frequency response is required of the direct sound between 250 Hz to 20 kHz on the listening axis (which is in most cases 10° - 20° of the speaker axis)
b) a flat total frequency response (including reverberation) is required between 250 Hz and 1 - 2.5 kHz (2.5 kHz according to IEC 268-13 reviewed for constant reverberation time form 250 Hz up to 8 kHz, 1 kHz according to Russell) with a curve of -x dB/octave above 1 - 2.5 kHz. x being 1 to 4 dB/oct.
Since most rooms have a constant reverberation time above 300 - 400 Hz, this means a constant directivity between between 250 Hz and 1 - 2.5 kHz and an increasing directivity for higher frequencies.
The measurements that John Atkinson takes of commercial loudspeakers in reviewers rooms and his comments on tonal neutrality suggest the crossover frequency to be rather 2 kHz than 1 kHz.
There are many options to achieve the constant directivity between 250 Hz and 1 - 2.5 kHz: omnidirectional, halfspace (wide baffle), dipole, cardioid. The total response slope above 2 kHz is best done with a horn optimized to achieve the required decreasing directivity with frequency(not optimized for maximum efficiency). Although a series of piston drivers with decreasing radius each covering little over an octave is also a theoretical option.
The frequency response between 150 Hz to 500 Hz is however strongly dependent on comb filtering caused by reflections of the floor, sidewall and backwall. My experiments (and countless room simulations) have proven that removing just the backwall reflection in this frequency range solves the most critical problems.
In short: a cardioid response between 150 Hz to 500 Hz is beneficial for tonal accuracy and allows speakers to be moved closer to a back wall.
A wide dipole with a panel + absorber behind it is also a solution.
Below 150 Hz the speakers can be omnidirectional again:
- a driver on the back with the required time delay and high pass filtered above 150 Hz.
- a driver on the back running in phase without time delay below 150 Hz and in opposite phase with time delay above 150 Hz: this requires a quite long FIR filter in DSP, but has the advantage that the lowest frequencies are reproduced by both the drivers and that the acceleration forces on the cabinet are cancelled.
Below 80 Hz I recommend separate subwoofers in more optimal room locations.
Is this cardioid worth the complexity? The speaker positioning becomes less critical to achieve an acceptable tonal balance in the midrange, especially in medium sized rooms. For a speaker design that also achieves a very high quality on most other parameters, I certainly would consider it.
The absorption wedges I designed for my company's anechoic room were ordered at and cut to shape by our packaging supplier (Kramo in Buggenhout). I do not know if they still exist, but small quantities of even specialist foams were no problem for a packaging supplier.
I am not sure how DIY has lessened the exposure that Dr. Geddes receives, when the blog format or message board has become a competitive information dissemination in comparison to high cost books, even with Kindle and the newly minted electronic renting format Amazon has now.
I believe DIY moves the ball forward conceptually until the processes of experimentation and optimization in people's own backyards using specialized computer programs and technically biased testing, such as here in this thread, so that the esoteric becomes commonplace and the virtue is better sonics in the main. No longer is the design criteria the ivory tower it was once, and the technobabble and mathiness have come full circle to a place where what once was achieved with massive R&D and doctoral thesis, translates into Joe Blow and his Best Buy receiver pushing 25 dollar waveguides and 150 dollar pro woofers.
I'm saying that the state of the art will constantly be movable, but without the involvement of those like Dr. Geddes, would we give the directivity criteria it's same weighting in the fundamentals?
I believe we need our idols, even if they tire of wearing capes and saving babies.
I believe DIY moves the ball forward conceptually until the processes of experimentation and optimization in people's own backyards using specialized computer programs and technically biased testing, such as here in this thread, so that the esoteric becomes commonplace and the virtue is better sonics in the main. No longer is the design criteria the ivory tower it was once, and the technobabble and mathiness have come full circle to a place where what once was achieved with massive R&D and doctoral thesis, translates into Joe Blow and his Best Buy receiver pushing 25 dollar waveguides and 150 dollar pro woofers.
I'm saying that the state of the art will constantly be movable, but without the involvement of those like Dr. Geddes, would we give the directivity criteria it's same weighting in the fundamentals?
I believe we need our idols, even if they tire of wearing capes and saving babies.
I think both statements need to be “decreasing directivity”, or am I missing something?
There is an ugly side to DIY, the part where some people want or expect something for nothing or as near as dammit.
This is greed, just as much as ultra high end prices can be a form of greed.
Without commercial HiFi product the DIY side could not exist the way we know it today, this is not an opinion it is simply a flat fact. Economics of big business drive manufacturing and R&D.
It makes my blood boil when I see people moaning that they could get this or that component and pay X amount less than any given commercial venture, it shows complete ignorance and a total lack of understanding of the real world commercial market.
This thread would likely not exist without Dr Geddes influence on DIY.
This is greed, just as much as ultra high end prices can be a form of greed.
Without commercial HiFi product the DIY side could not exist the way we know it today, this is not an opinion it is simply a flat fact. Economics of big business drive manufacturing and R&D.
It makes my blood boil when I see people moaning that they could get this or that component and pay X amount less than any given commercial venture, it shows complete ignorance and a total lack of understanding of the real world commercial market.
This thread would likely not exist without Dr Geddes influence on DIY.
it does make one wonder if everyone understands how much audio is available now from the work of others, as it is we stand on the shoulders of giants.
Anyone can co-opt a great design and fabricate the approximate equal using high cost "singles" construction practice, it's when a great design is made cheaper that it becomes part of the industry, as a mass marketed and produced item that people tend to relegate the design to a 'one of many' fold.
Geddes has yet to do such a thing, perhaps caring too much about keeping what he created an in-house venture, perhaps commercial success is less important than commercial control.
Is that a bad business decision? In a capitalist society it would be similar to a supply and demand problem, a marketing issue, an advertising concern, but I think it is at it's heart a beautiful exposition on the refusal to succumb to the mass market prevarication, it will not be parallel to the common goals of profits, making and sharing. It is not our right to force a low cost product out of Dr. Geddes, as attractive and as end-game sounding as that is.
If we never do see the widespread implementation of the foam plug and diminished HOM across the globe, those who were lucky enough to have shared in the process of discovery on this board's pages know where the homage recipient resides, we know...
Anyone can co-opt a great design and fabricate the approximate equal using high cost "singles" construction practice, it's when a great design is made cheaper that it becomes part of the industry, as a mass marketed and produced item that people tend to relegate the design to a 'one of many' fold.
Geddes has yet to do such a thing, perhaps caring too much about keeping what he created an in-house venture, perhaps commercial success is less important than commercial control.
Is that a bad business decision? In a capitalist society it would be similar to a supply and demand problem, a marketing issue, an advertising concern, but I think it is at it's heart a beautiful exposition on the refusal to succumb to the mass market prevarication, it will not be parallel to the common goals of profits, making and sharing. It is not our right to force a low cost product out of Dr. Geddes, as attractive and as end-game sounding as that is.
If we never do see the widespread implementation of the foam plug and diminished HOM across the globe, those who were lucky enough to have shared in the process of discovery on this board's pages know where the homage recipient resides, we know...
@Earl
Did you have a closer look at the data Keyser has send you. I would really like to hear your opinion about them...
I tried to open your polar program on your website (to see if you had mayde uploaded keysers data), but the program is not working (see attached error log)
Its good to see that so many actually do understand the complicated aspects of business decisions.
What would be my ideal? To find someone or some company who could push the production of my designs into the next level because a truely remarkable line of loudspeakers could be made and sold at incredibly competitive prices. But alas, that has not happened, and in this economy no one seems to be willing to take that risk, including me. So the production remains very low volume at fairly high prices. WIll this change? Not very likely in this economy. My products appeal most to that segment of the market who is hardest hit by the current downturn (the "good value" crowd). The very wealthy (who have not been affected at all, in fact are all doing very well with tax cuts and all) actually want to pay much more than my prices, but they want much more flash as well. They insist that the speakers that they buy appear on the cover of some magazine. That they be instantly recognizable to their friends and relatives. That takes a lot of money to achieve.
I would love to stop making loudspeakers so that I could do the kind of R&D that led to the current designs. I have not been able to do that in years.
I did get Keyser's data and I am starting to look at it, but since it is not HolmImpulse data (my standard) I have to modify it (and the software) to be compatible with my software.
As to the polar program on the web, I know for a fact that it will only run on a Windows machine under MS Explorer. No other platform will work. But if you have that platform and it doesn't work then please let me know.
What would be my ideal? To find someone or some company who could push the production of my designs into the next level because a truely remarkable line of loudspeakers could be made and sold at incredibly competitive prices. But alas, that has not happened, and in this economy no one seems to be willing to take that risk, including me. So the production remains very low volume at fairly high prices. WIll this change? Not very likely in this economy. My products appeal most to that segment of the market who is hardest hit by the current downturn (the "good value" crowd). The very wealthy (who have not been affected at all, in fact are all doing very well with tax cuts and all) actually want to pay much more than my prices, but they want much more flash as well. They insist that the speakers that they buy appear on the cover of some magazine. That they be instantly recognizable to their friends and relatives. That takes a lot of money to achieve.
I would love to stop making loudspeakers so that I could do the kind of R&D that led to the current designs. I have not been able to do that in years.
I did get Keyser's data and I am starting to look at it, but since it is not HolmImpulse data (my standard) I have to modify it (and the software) to be compatible with my software.
As to the polar program on the web, I know for a fact that it will only run on a Windows machine under MS Explorer. No other platform will work. But if you have that platform and it doesn't work then please let me know.
I am not sure that I completely agree. Part a) is fine, no major problems (except as noted below), but part b) I have an issue with.
If in part b) you mean the "power response" then you should say so. I would question the need for this to go down to 250 Hz as the ear is simply not that sensitive to reflections and such below 500 Hz. I would say 500 Hz and up, agreed. A small HF roll off is desirable in the power response, as this part suggests, but you say that this should be achieve with an increasing directivity and to that I disagree. I believe that the directivty needs to stay constant but that the power response should fall, which means, of course, a subtle fall in the listening axis response. Theses approaches are quite different.
And there is no mention of what the directivity should be, as if it doesn't matter. Early room reflections matter a lot and this is strongly influence by the directivity - its not arbitrary.
As to floor and ceiling refelctions, I have only ever found dealing with the room in this regard to be very effective. Any back wall reflection is always a negative thing and no amount of absorption behind the loudspeakers is too much. But a forward facing high directivty helps the back wall situation no matter how much absorption is present.
Thanks for your valuable comments Earl.
The total frequency response (direct + reverberation) at the receiver will be similar to the power response of the source:
- above the Schroeder frequency,
- if the decay time is constant over the frequency range,
- if the receiver distance is larger than the critical distance (reverberation radius)
- if the source to boundary distance > wavelength.
The first 3 conditions will be met in most cases, the last one not always down to 250 Hz. Thus I prefer not to use "power response" in this case, this being albeit academic.
You correctly mention that below 500 Hz we do not perceive reflections as reflections (no change in localisation, source width etc.), but these still give rise to perceivable resonances in the frequency response.
My comment did only focus on a neutral tonal reponse, and I certainly did not intend to make this more important than the early reflections (relative amplitude and delay) (or power compression, or subwoofer placement, ...). I would consider the extra speaker at the back only "for a speaker design that also achieves a very high quality on most other parameters".
To all: I noticed that my use of "backwall reflection" could be confusing; I was thinking from a source perspective. From the listener viewpoint this is the front wall. (Earl did make the correct interpretation).
It would be interesting to compare both solutions in a perception test (panel + questionnaire), because even with the extensive knowledge of auditory perception and room acoustics, I have no idea which one is to be preferred.
The total frequency response (direct + reverberation) at the receiver will be similar to the power response of the source:
- above the Schroeder frequency,
- if the decay time is constant over the frequency range,
- if the receiver distance is larger than the critical distance (reverberation radius)
- if the source to boundary distance > wavelength.
The first 3 conditions will be met in most cases, the last one not always down to 250 Hz. Thus I prefer not to use "power response" in this case, this being albeit academic.
You correctly mention that below 500 Hz we do not perceive reflections as reflections (no change in localisation, source width etc.), but these still give rise to perceivable resonances in the frequency response.
My comment did only focus on a neutral tonal reponse, and I certainly did not intend to make this more important than the early reflections (relative amplitude and delay) (or power compression, or subwoofer placement, ...). I would consider the extra speaker at the back only "for a speaker design that also achieves a very high quality on most other parameters".
To all: I noticed that my use of "backwall reflection" could be confusing; I was thinking from a source perspective. From the listener viewpoint this is the front wall. (Earl did make the correct interpretation).
It would be interesting to compare both solutions in a perception test (panel + questionnaire), because even with the extensive knowledge of auditory perception and room acoustics, I have no idea which one is to be preferred.
I use win 7 pro (64 bit)with ms explorer. I tested on a pc with XP and got the same problem. The forum does not allow me to add the log file, so here is it content:
PLATFORM VERSION INFO
Windows : 6.1.7601.65536 (Win32NT)
Common Language Runtime : 4.0.30319.235
System.Deployment.dll : 4.0.30319.1 (RTMRel.030319-0100)
clr.dll : 4.0.30319.235 (RTMGDR.030319-2300)
dfdll.dll : 4.0.30319.1 (RTMRel.030319-0100)
dfshim.dll : 4.0.31106.0 (Main.031106-0000)
SOURCES
Deployment url : http://www.gedlee.com/Polar_map.application
Server : Microsoft-IIS/6.0
X-Powered-By : ASP.NET
Application url : http://www.gedlee.com/Application Files/Polar_map_1_1_0_15/Polar_map.exe.manifest
Server : Microsoft-IIS/6.0
X-Powered-By : ASP.NET
IDENTITIES
Deployment Identity : Polar_map.application, Version=1.1.0.15, Culture=neutral, PublicKeyToken=e3fbc8468c33b92b, processorArchitecture=x86
Application Identity : Polar_map.exe, Version=1.1.0.15, Culture=neutral, PublicKeyToken=e3fbc8468c33b92b, processorArchitecture=x86, type=win32
APPLICATION SUMMARY
* Online only application.
* Trust url parameter is set.
ERROR SUMMARY
Below is a summary of the errors, details of these errors are listed later in the log.
* Activation of http://www.gedlee.com/Polar_map.application resulted in exception. Following failure messages were detected:
+ Downloading http://www.gedlee.com/Application Files/Polar_map_1_1_0_15/Polar_map.exe.config.deploy did not succeed.
+ The remote server returned an error: (404) Not Found.
COMPONENT STORE TRANSACTION FAILURE SUMMARY
No transaction error was detected.
WARNINGS
There were no warnings during this operation.
OPERATION PROGRESS STATUS
* [22/08/2011 21:24:14] : Activation of http://www.gedlee.com/Polar_map.application has started.
* [22/08/2011 21:24:14] : Processing of deployment manifest has successfully completed.
* [22/08/2011 21:24:14] : Installation of the application has started.
* [22/08/2011 21:24:14] : Processing of application manifest has successfully completed.
* [22/08/2011 21:24:17] : Found compatible runtime version 2.0.50727.
* [22/08/2011 21:24:17] : Detecting dependent assembly Sentinel.v3.5Client, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=msil using Sentinel.v3.5Client, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=msil.
* [22/08/2011 21:24:17] : Detecting dependent assembly System.Data.Entity, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089, processorArchitecture=msil using System.Data.Entity, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089, processorArchitecture=msil.
* [22/08/2011 21:24:17] : Request of trust and detection of platform is complete.
ERROR DETAILS
Following errors were detected during this operation.
* [22/08/2011 21:24:17] System.Deployment.Application.DeploymentDownloadException (Unknown subtype)
- Downloading http://www.gedlee.com/Application Files/Polar_map_1_1_0_15/Polar_map.exe.config.deploy did not succeed.
- Source: System.Deployment
- Stack trace:
at System.Deployment.Application.SystemNetDownloader.DownloadSingleFile(DownloadQueueItem next)
at System.Deployment.Application.SystemNetDownloader.DownloadAllFiles()
at System.Deployment.Application.FileDownloader.Download(SubscriptionState subState)
at System.Deployment.Application.DownloadManager.DownloadDependencies(SubscriptionState subState, AssemblyManifest deployManifest, AssemblyManifest appManifest, Uri sourceUriBase, String targetDirectory, String group, IDownloadNotification notification, DownloadOptions options)
at System.Deployment.Application.ApplicationActivator.DownloadApplication(SubscriptionState subState, ActivationDescription actDesc, Int64 transactionId, TempDirectory& downloadTemp)
at System.Deployment.Application.ApplicationActivator.InstallApplication(SubscriptionState& subState, ActivationDescription actDesc)
at System.Deployment.Application.ApplicationActivator.PerformDeploymentActivation(Uri activationUri, Boolean isShortcut, String textualSubId, String deploymentProviderUrlFromExtension, BrowserSettings browserSettings, String& errorPageUrl)
at System.Deployment.Application.ApplicationActivator.ActivateDeploymentWorker(Object state)
--- Inner Exception ---
System.Net.WebException
- The remote server returned an error: (404) Not Found.
- Source: System
- Stack trace:
at System.Net.HttpWebRequest.GetResponse()
at System.Deployment.Application.SystemNetDownloader.DownloadSingleFile(DownloadQueueItem next)
COMPONENT STORE TRANSACTION DETAILS
No transaction information is available.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.