thadman, you can sell a product only for the price people are willing to pay.
There are people in Germany that buy re-imported cars because they are cheaper. That's insane. A car produced in Germany for the US market, shipped to the States, shipped back and modified (to get approval by German authorities) is cheaper than the same car bought at a local dealer.
There are people in Germany that buy re-imported cars because they are cheaper. That's insane. A car produced in Germany for the US market, shipped to the States, shipped back and modified (to get approval by German authorities) is cheaper than the same car bought at a local dealer.
Ouch! The same thing happens in Japan and America/China. I love going to Japan and selling my Japanese made goods to the locals for more than I paid for them and less than they can get them locally. Even a year after the initial purchase. I've done it a couple times. Nothing better than getting paid to use something for a year. You should see what the Japanese are willing to pay for old German HiFi. You could fund a heck of a trip with a suitcase of relatively cheap Telefunken tweeters or any Telefunken, SABA, etc... stuff.
Dan
Thats a really big thing with me. Value engineering is the only engineering worth doing (i.e. Honda in the car industry). If your not trying to make something to sell with the best "value" then its not worth doing. These days engineering is always short changed and the price and profits are boosted with marketing - more marketing guys - fewer engineers. That simply does not impress me in the least. It sickens me how well it works though.
You simply will not find a better deal in loudspeakers than buying mine on the internet. Geddes Loudspeaker Co. - engineering 98%, marketing 2%.
Getting back to thermal compression:
VC Heating
It not sure that at this point I believe the results myself, but it is what the physics says and seems to be born out by other considerations as well. Comments?
VC Heating
It not sure that at this point I believe the results myself, but it is what the physics says and seems to be born out by other considerations as well. Comments?
Runs in the family.
When you did your tweeter analysis you assumed a single pulse and that is unrealistic. A single pulse is not going to do anything thermally. But a string of pulses will. Your analysis clearly shows that higher frequencies are the bigger problem which all my tests have shown and that at higher frequencies in small VC tweeters the effect can happen very quickly. I do believe that your conclusions are not born out by the analysis, assuming that it is correct. I just glanced through that part so I cannot comment, but the time scales seem like what I got, but I didn't use a simple single pulse. Assume broadband noise and the results are much different. Modulate that noise at the right frequency (basically at the tweeters VC thermal constant) and the tweeters output will modulate significantly.
That the effect is there is undeniable, but you are guessing that it is not audible. I would not do things in dB since that scale is not accurate for JNDs (Just Noticeable Differences), but even when dBs are used JND can be as low as .1 dB in some situations.
I have never said that thermal MODULATION, which I still contend you are not getting at (yours is a quasi-steady state analysis), is the answer to "dynamics", only that it does exist, and that the "simple analysis", as you have done, does NOT preclude that it could be audible. I only maintained that it was a real effect, because I have measured it.
Wish that I could follow up with my own analysis, but I simply don;t have that kind of time available.
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I have similar feelings too. But one of the challenges is how to get a a concept to change the market without breaking the pocket. Not an easy answer.
I don't follow. Do you mean "How to change the market without having to spend a lot of money doing it"? If so, I agree, because its self defeating either way, your damned if you do and damned if you don't. My plan is just to keep the course, either luck will direct the stream my way or it won't. In which case poor quality at high prices with loads of marketing will continue to rule the day - long live Bose!
I approached this without any bias. The results show a short terms burst will not result in thermal compression. On the other hand, just how hot do you think the VC gets? Look at the figure at the bottom of the page. Yes a succession of pulse may result in greater heating, but the pulses will have th be separated by a time much shorter than the relaxation time for the VC and they will have to persist for a long time. Each individual pulse will not be significantly compressed. But over time the overall performance of the system will show reduced sensitivity. So a system that started out at 90 dB may become 88 dB over time, but the dynamics of the impulse will not significantly change.
I'll be adding cooling at some point and, while I may not get is correct in terms of relaxation time, I will be able to look at the effect of cooling parametrically, i.e. I will be able to set the cooling rate and see how it affects the results.
Also, as I state in the discussion, the current sims are worst case results. Music doesn't contain flat top pulses, unless the signal is clipped. So look again at the tweeter result. The heating would be even less if the pulse were as that which actually gets through the x-o.
I don't need to consider thermal modulation to see what happens to a short term transient. The transient is supperimposed on what ever temperature the VC is at when the transient starts. Again, as stated, starting with the VC at room temperature gives the most rapid rate of heating because as the VC heats Re increases and the power dissipated for the same pulse becomes less.
By the way Earl, if you can hear 0.1 dB changes in a transient which peaks 10 or 20 dB above the average level your a much, much better man that I.
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It didn't read like that.
"a succession of pulse may result in greater heating" - no John, it WILL result in greater heating - two pulses, twice the heat, three, three times, etc. It doesn't take many pulses until you have a lot of heating. Your own data showed that a tweeter has time constants on the order of ms - thats what "over time" means here. Its not the effect on a single impulse that I am concerned with but the effect on a string of them, ala noise or music. I think you are looking at it the wrong way.
I looked at your results and see support that it is a possibility and you see it otherwise - what can I say.
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Germany, no, but England (via Malaysia) can certainly compete in terms of value with anyone. Better build quality than a Corvette, and no gold chains required.
Though it's unfortunate that Americans only get the mega-power version, because even the original Rover K-Series motor was plenty.
God I want one of those! I drove one (base model without the hardtop) for a little while in Vienna and, slushy semiauto aside it was just a sublime drive. It's the only car out there, short of an Elise with side sills low enough for easy ingress/egress and a footbox that doesn't have rough edges that scraped the top of a pair of $700 shell cordovan loafers I bought the day before my Elise test drive, that would be good enough to get me out of my 2001 Miata.
agreed. today there are better cars like Nissan GTR or Audi R8 5.2
even Porsche Cayman S is now considered to be better than 911. too bad Cayman doesn't come in turbo ( yet )
Did you know that Porsche designed a hybrid electric vehicle in 1941? It was called the Elephant. A diesal engine driving a generator and electric motors on each track. The first "production" use of such a system to my knowledge.
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