Looks like you are right Dave:
http://www.diyaudio.com/forums/multi-way/81814-damping-coating-substances-speakers-cones.html
http://www.diyaudio.com/forums/multi-way/81814-damping-coating-substances-speakers-cones.html
The phase plug design of the TD drivers improves their cooling. John has done measurements and the TDs cool as well or better than comparable JBLs with 4" coils. Next issue/gripe about the TDs? 🙂
Whatever John is using for cone damping, it remains tacky. He recommends a coat of Scotchgard teflon spray if you don't want dust to stick. I asked him about Armor All and got a lengthy reply about the evils of Armor All. 🙂
Yeah, I didnt do that and those drivers collect dust like crazy 🙁 I use the tape trick for removing dust....painters tape is perfect for cleaning the woofers.
here's a one week look at my cone geometry change.
June 16,2010:
Today, June 23,2010:
This might have something to do with why manufacturer's data is optimistic. Maybe they are testing fairly early on in the curing process.😕 Maybe this also has to do with the phenomenon of driver break in, not just what we see in T/S parameter changes. Anyone else who has measurement changes over time? It would be just as nice to see how "enable" and C34 or whatever your treatment of choice change over time.
Dan
June 16,2010:
Today, June 23,2010:
This might have something to do with why manufacturer's data is optimistic. Maybe they are testing fairly early on in the curing process.😕 Maybe this also has to do with the phenomenon of driver break in, not just what we see in T/S parameter changes. Anyone else who has measurement changes over time? It would be just as nice to see how "enable" and C34 or whatever your treatment of choice change over time.
Dan
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I know we beat this to death about 40 pages ago but you have a habit of posting negative comments about the work of others who have spent a large amount of time and money helping the DIY community.
They are complete enough to make rational driver selection and that is the only purpose they have. Augerpro does not think your requirements are necessary. Everyone else that uses Bradon's measurements are comfortable with all that he has done too. Did you ever ask Zilch or Pete on Techtalk why they do not conform to your particular measurement requirements either? None of the expert builders on HTGuide made comments saying those measurements are incomplete.
In the end we all still do measurements of our own builds. If you want specific measurements you have to do them yourself. I learned a long time ago that if you are going to tell everyone else they are doing it wrong you better go out spend the $$$ and time to do it right otherwise comments on how others do things are a waste of time.
No one is forcing you to use them anyways so stop complaining about them.
They are complete enough to make rational driver selection and that is the only purpose they have. Augerpro does not think your requirements are necessary. Everyone else that uses Bradon's measurements are comfortable with all that he has done too. Did you ever ask Zilch or Pete on Techtalk why they do not conform to your particular measurement requirements either? None of the expert builders on HTGuide made comments saying those measurements are incomplete.
In the end we all still do measurements of our own builds. If you want specific measurements you have to do them yourself. I learned a long time ago that if you are going to tell everyone else they are doing it wrong you better go out spend the $$$ and time to do it right otherwise comments on how others do things are a waste of time.
No one is forcing you to use them anyways so stop complaining about them.
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And that is the bottom line. You have no choice but to do them yourself in your own box, under conditions that are repeatable in your own specific test enviornment. It's nice looking at others guys measurements. It's even more fun when you get correlation from another builder 3000 miles away. That said I would never build a speaker based on another home builders measurement set. Too many variables.
Rob🙂
Agreed - reluctantly. There is no reason that a standard can't be reached that makes the measurements comparable. I tried to argue this point very early on in this thread. The fact is that everybody WANTS to do everything their own way and very often that isn't right. So here we are, and sadly, what you say is true.
Dan gets criticized for making this same point and yet when Augerpro did all his measurements I tried to get him to do them differently - in a way that would make them more useful. But he did it "his way". Thats fine, but please lets not chastise people for TRYING to come to some sort of agreement on whats needed. I agree with you Dan.
Reaching a standard way is desireable, but it can never be done because there are so many difference in opinion as to what data is relevant and what not. For example, I find almost all forms of measurements are useful in some way, but you seem to only accept that only a handfull of measurements are usefull. This makes a huge difference in the scope of a standard.
If it's possible to go through the various methods one by one, and sort out the usefull parts of each, then maybe...
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This thread has just come full circle: what metrics are the most important and why? Then how to do them in a universally useful way?
Dan
Dan
Thanks Dr. Geddes. It's just Doug being Doug. I pay it no mind. My remarks about Augerpro's measurements were complimentary thus my statement about them being the best I know of. It seems Doug thought it an insult. I can't explain it. My demo earlier in the thread explains my position, he has nothing to explain his or his personal experts'. There's still no reasoning with belief. Why does this remind me of 'lowering the standard'. I've tried before and he was unable to make a single point, but refused to expand his understanding.
The problem is, I haven't found anything to reliably predict a woofer's off axis break up performance and I've demonstrated it's importance. No one else I know of can predict it either and I've done a bit of searching on the topic. IOW, real data would be helpful. Without it, it's more of a guess.
Dan
Hello Dan
I doubt you will. Manufacturers certainly are not going to share it with you. As far as measurements, people are going to do what they are comfortable doing. If they have a "standard set" that they use and it gets them consistent results that they are happy with, well that's what they are going to do. That's what I do. I am open minded to trying new things and improve upon what I already do but I am not going to abandon what I feel works for me. I might add to it and after a time if the changed or added tests are more effective than I would change to them. But there is going to be some initial resistance to changing ones "tried and true" techniques.
I think it would be a big plus to have a Standard as it does make what you see posted much more useful. But to be honest even if we had a "Standard Measurement Set" I still wouldn't trust another persons measurement set to do my own builds.
Rob🙂
I'm going to assume Mr. Klippel is working on this since he is working on distrubuted parameters. I am also going to assume that if it's possible to generate these parameters from FEA, then it would be possible to predict the polar response.
It is certainly possible, its been done for several decades now. The point is that it hasn't really changed anything. I mean there are still breakup modes, they aren't going away. Sure we can calculate where they are and how bad they get, but that hasn't changed the fact that they will always exist and once they start to happen the driver isn't useful anymore.
When I went to school for my PhD it was with the specific intention to learn FEA and apply it to loudspeakers. I did that and learned very early on that FEA didn't improve anything. It didn't really make the loudspeakers better, you just had a more detailed look at how bad they are. After a few years of applying it, I moved on to other things that worked out far better. I haven't used FEA in almost 20 years. I much prefer other approaches.
When I went to school for my PhD it was with the specific intention to learn FEA and apply it to loudspeakers. I did that and learned very early on that FEA didn't improve anything. It didn't really make the loudspeakers better, you just had a more detailed look at how bad they are. After a few years of applying it, I moved on to other things that worked out far better. I haven't used FEA in almost 20 years. I much prefer other approaches.
Having looked at various drivers from Ted Jordan, certainly the breakup modes are not significantly shown. I am wondering how many people have actually studied this. Looking at some of the software specifically designed for speaker driver design, I have not seen anything that does the FEA that looks like what a real driver cone vibrates like. Since most only allow axisymetric design, I think there are some of the 3D forces that are not done correctly after looking at some sims.
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