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#562
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(Nousaine) wrote in message ...
"Wessel Dirksen" wrote: "Michael McKelvy" wrote in message ... "Nousaine" wrote in message ... "Michael McKelvy" wrote: ....snip to content...... I don't know why I'd trust anybody that still sells the break-in mythology. :-) compensation. But again, why would I want to trust people who still subscribe to the speaker break-in urban legend? For the same reason I wouln't write off someone who sells finished speakers that tout the fact that they have gold plated terminals, it's about marketing and doesn't really do any harm. I know your position on break-in and my expierience is the same, but it is limited. There is a car speaker company's web site I visited that had specs on before and after break-in on their drivers, there was a difference albeit a small one. I don't have a 'position' on break-in. I've conducted more than one extensive experiment testing the hypothesis. It is true that you can 'measure' changes in Fs and Vas immediately after a long break-in period when the voice coil is still hot. But those changes are 1) off-setting in regard to cabinet design and 2) return to previous values after a few hours rest. Fs and Vas are mechanical properties and have no dependance on the electrical properties of the voicecoil whatsoever. Even if the voicecoil could theoretically double it's Rdc from overheating (impossible without damage), the Fs and Vas and therefore Qm would not be affected. But a hot voicecoil will increase Qe and therefore overall Qt will increase until the VC cools down. What you say may be true but the calculation of Vas is dependent on measuring the impedance curve and Fs and Re and Q does change and so do the calculated values of Vas. But, and this is the important point is that they fall back to 'fresh' values as the voice coil cools down. It may be true that this phenomenon may be independent of the latter but the real point is that speakers DO NOT break in. At best it can be said that they may WARM UP. But because performance doesn't change why would anyone care? Vas is not actually determined from the free air impedance curve since it is dependant on Cms, Sd and air density, but that is not the issue here. We, and the others still involved with this issue, are in agreement here that break in as far the drivers themselves are concerned is at best an issue of the past. What is of importance is how the drivers mechanical properties are affected by ambient conditions of which ambient temperature is most critical. Temperature related voice coil compression from overheating is a functional matter that is always relevant. But the affect of ambient temperature on driver characteristics is not insignificant! System compliance varies greatly in the cold and can lead to more than a 10% change in Fs at even 50 deg F. This is why drivers intended for indoor use are developed, and T/S specifications are considered representative, at operating temperatures between 20 and 25 deg C. If one leaves the heat off during the day in an environment with cold winters, this is exactly what is happening. Speakers tend to sound rather lifeless until first the room, then the speakers warm up. Polypropylene cones are especially notorious for extra buckling at higher temperatures. I discovered this myself in turn to hear from driver developers that they have been struggling with this for years. A typical warm summer can cause the living room to heat up to 80 deg F.unless you keep the AC on the whole time. This affects the sound of speakers, especially FR in polypropylene models. The ambient temperature can significantly affect Cms where an increase in temperature increases system compliance and leads to increased Vas and decreased Fs which in turn increases overal Q. So the weather has a greater influence on the mechanical properties of a driver than most other factors. Sure. But that simply says that speakers do not break-in. Agreed Driver break-in is much less of an issue these days mainly because the industry has for awhile now demanded low assembly line unit to unit variability and polymer technology has made this possible. Break in, when present in the driver itself is usually in only in the amount of hysteresis leading to dicernable differences only when the cone is barely moving. Meaning when Theil/Small parameters are generally measured :-) A very common and very audible "break in" phenomena when first taking speakers home is due to external factors. The ambient temperature changes from warehouse to car etc and temporarily changes mechanical compliance. Often a speaker is not stocked in the same orientation as it is used, so that internal damping materials often shift during the first days of use and this can be very discernable. Even the re-location from a different elevation can cause an atmospheric pressure gradient with a sealed midrange driver leading to a break-in phenomena for a few days until equalibrium has been reached. I'm guessing that elevation and storage equibrium is reached within a few seconds. If you have some more data I'd be glad to hear it. Well I'll tell you a story. A customer of mine awhile back lived in Redlands, California (elevation +/- 500 ft) and had a cabin at Big Bear Lake (elevation +/- 6000 ft) that he frequently went to for a few weeks at a time. He had a pair of one the smaller B&W Nautilus speakers to first use the now common stiff larger 6" midrange driver (I don't know the model number). Because he liked these speakers he took them with him every time he went to his cabin. He noticed that they sounded quite bad for a few days until they sorted themselves out. When he contacted me about this, I explained the temperature thing as a hypothesis, and he went to great lengths to correct for this. A neighbor turned on the heat at the cabin a day in advance, he pre-heated the car prior to loading, and he carried them outside wrapped in a couple of sleeping bags. The problem didn't seem to go away. We decided to look inside since he was considering mod's anyway. In one of the speakers, a glob of glue had fallen on the leak hole in the midrange enclosure. Also inspecting the driver and mounting seal, it didn't appear that air was going to get out easily. Once this was removed, the problem went away. This is a little exceptional perhaps but it proves the point |
#563
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(Nousaine) wrote in message ...
John Stone wrote: in article , Nousaine at wrote on 7/31/04 4:26 PM: Some vendors will match your drivers for specs for an additional fee, I believe NorthCreek is one of them. And how do they do that? It's been my experience that often the drivers marketed to the DIY market seem to be end-of-run, out-of-spec orr OEM rejected drivers that may not even have the same parts as listed in the catalog. That's OK but they need to be verified not only for T/S parameters but also frequency response. For example I once purchased Dynaudio drivers for a custom powered speaker system. Not only was the Fs of the woofers a half octave higher than advertised they weren't even within 10 Hz of each other. This required significant design compensation. Why do you keep resurrecting this old wives' tale, Tom? It's not an old wive's tale. It's a given experience. And it's one of the reasons that I stopped making speakers,other than subwoofers 10 years ago. Where is your evidence that today's DIY drivers are end run, OEM rejects, or out-of-spec? I don't have any evidence that this is the case other than never having bought a driver from anybody, other than tweeters, that didn't require more investigation than specifications from the vendor for design purposes. My present company (SEAS) and my previous company (Vifa/Scan-Speak) would never allow out of spec drivers to leave the factory-ever. In fact, each SEAS product is fully tested for Fs, frequency response, and rub/buzz before it ever leaves the factory. Anything that goes to a product distributor like Madisound is virtually identical to the same product sold to an OEM. I think you may both be right. John's perspective may be a bit positively skewed because he works for Seas who in my experience have the best unit to unit tolerances in the business. Actually there's pretty much nothing bad you can say about Seas. Focal seem to be consistantly inconsistant with the individual units I've had but not terrible per se, in that the drivers I have had would have still passed reasonable assembly line tolerances compared to published spec's. I have to side with Tom on Dynaudio though. I once had two 17W75's (out of +/- 12 units total) with a spec'd Fs and a Qt of 1.1!! (in comparison to 0.74 with normal Fs and Rdc that represents a magnetic gap flux down close to 50%) I've had 4 20W-75's before of which two of them had an Fs of 55 (almost an octave to high) I've never worked with OEM units from either to know how units from the same series compare. Haven't used enough Scanspeak woofers to know about them either. I've seen some loosey goosey Vifa drivers in my day as well, but I rarely use Vifa woofers anymore so I don't know anymore. In the early to mid 90's, I found that polymer surrounds of several Vifa units got severely stiff in just a few years time in both Southern California and in The Netherlands. Seas drivers don't seem to have this. Actually, about 6 months ago, I got an old project from 1995 back in my hands that had Seas CA21-RE's in them. Because I write the T/S parameters on the magnets of every individual driver I happen to measure, I re-tested this unit and it was still spot on even being tortured in an aggressive bandpass cabinet. A little further up in this thread ambient temperature was addressed as it can certainly affect T/S measurement, so measuring a driver's parameters in a hot or cold garage is asking for surprizes. |
#564
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John Stone wrote in message ...
in article , Nousaine at wrote on 8/4/04 7:05 PM: And the better sounding ones cost a lot more in terms of cash outlay. The Thor is around $1500.00. Have you heard it? No. But John Stone reported on the Seas Odin kits he uses; and after checking these on the Madisound website they are actually more expensive than the excellent PSB Stratus Mini. So is this kit. Yes, but are you then assuming that the 2 are qualitatively equal? Let's compare them. The PSB is a 6-1/2 2-way with a Vifa P17WJ 17cm and D19AD 19mm alu dome tweeter. The Odin is a WTW with 2 6-1/2" SEAS Excel woofers and a 25mm "Millennium" soft dome tweeter. At this point John has said enough. This is apples vs. oranges. If both kits are designed reasonably, based on components, the later will tear up the former left, right and sideways. This is like comparing a Saturn to a BMW M5. |
#565
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Hi John,
I recently bought the H1224 Drivers from Madisound. Can you shed some light on how they evolved from the H 1142? Thanks! John Stone wrote: in article , Nousaine at wrote on 7/31/04 4:26 PM: Some vendors will match your drivers for specs for an additional fee, I believe NorthCreek is one of them. And how do they do that? It's been my experience that often the drivers marketed to the DIY market seem to be end-of-run, out-of-spec orr OEM rejected drivers that may not even have the same parts as listed in the catalog. That's OK but they need to be verified not only for T/S parameters but also frequency response. For example I once purchased Dynaudio drivers for a custom powered speaker system. Not only was the Fs of the woofers a half octave higher than advertised they weren't even within 10 Hz of each other. This required significant design compensation. Why do you keep resurrecting this old wives' tale, Tom? Where is your evidence that today's DIY drivers are end run, OEM rejects, or out-of-spec? My present company (SEAS) and my previous company (Vifa/Scan-Speak) would never allow out of spec drivers to leave the factory-ever. In fact, each SEAS product is fully tested for Fs, frequency response, and rub/buzz before it ever leaves the factory. Anything that goes to a product distributor like Madisound is virtually identical to the same product sold to an OEM. The better Danish Sound Technology products are likely the same. While I can't speak for cheap Chinese drivers and other such stuff, I can say that these 2 Scandinavian companies account for a huge chunk of the DIY driver market. As for your Dynaudio experience, I'm wondering if your high Fs problem didn't stem at least partially from using a different measuring voltage than Dynaudio did. Many measuring systems; e.g., MLSSA , simply don't put enough low frequency energy into the driver to get the suspension working in a linear fashion. All surrounds, especially high loss types, have some degree of hysteresis, and at low measurement levels a driver will exhibit precisely the problem you describe. At any rate, the point is moot given that Dynaudio stopped stopped selling to the DIY market years ago. Focal and Audax are both exiting this market as well. Regarding DIY systems, I've heard some absolutely fantastic designs; IMO as good as anything commercially available. But-and this is a big but-it takes someone with a lot of talent and measurement capability to accomplish this. My present living room system uses the SEAS Odin kit (designed by Joe D'Appolitto) coupled to a commercial subwoofer. It sounds very good indeed. |
#566
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(Wessel Dirksen) wrote:
John Stone wrote in message ... in article , Nousaine at wrote on 8/4/04 7:05 PM: And the better sounding ones cost a lot more in terms of cash outlay. The Thor is around $1500.00. Have you heard it? No. But John Stone reported on the Seas Odin kits he uses; and after checking these on the Madisound website they are actually more expensive than the excellent PSB Stratus Mini. So is this kit. Yes, but are you then assuming that the 2 are qualitatively equal? Let's compare them. The PSB is a 6-1/2 2-way with a Vifa P17WJ 17cm and D19AD 19mm alu dome tweeter. The Odin is a WTW with 2 6-1/2" SEAS Excel woofers and a 25mm "Millennium" soft dome tweeter. At this point John has said enough. This is apples vs. oranges. If both kits are designed reasonably, based on components, the later will tear up the former left, right and sideways. This is like comparing a Saturn to a BMW M5. Oh for Pete's sake. The finished PSB costs 2/3 of the kit. For an even price comparison, and if you want to play the driver-count game, you can get a pair of fully finished Paradigm Studio 60s for $1500 or a pair of Studio 40s for $1100. Both with full warranties. Everyone wants to ignore that you aren't going to save money or get demonstrably better performance, even with a high quality kit, compared to what's commercially available. Sure there are lots of even more expensive "high-end" speakers that aren't worth the paper the reviews are printed on --- so what? |
#567
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(Wessel Dirksen) wrote:
(Nousaine) wrote in message ... "Wessel Dirksen" wrote: "Michael McKelvy" wrote in message ... "Nousaine" wrote in message ... "Michael McKelvy" wrote: ....snip to content...... I don't know why I'd trust anybody that still sells the break-in mythology. :-) compensation. But again, why would I want to trust people who still subscribe to the speaker break-in urban legend? For the same reason I wouln't write off someone who sells finished speakers that tout the fact that they have gold plated terminals, it's about marketing and doesn't really do any harm. I know your position on break-in and my expierience is the same, but it is limited. There is a car speaker company's web site I visited that had specs on before and after break-in on their drivers, there was a difference albeit a small one. I don't have a 'position' on break-in. I've conducted more than one extensive experiment testing the hypothesis. It is true that you can 'measure' changes in Fs and Vas immediately after a long break-in period when the voice coil is still hot. But those changes are 1) off-setting in regard to cabinet design and 2) return to previous values after a few hours rest. Fs and Vas are mechanical properties and have no dependance on the electrical properties of the voicecoil whatsoever. Even if the voicecoil could theoretically double it's Rdc from overheating (impossible without damage), the Fs and Vas and therefore Qm would not be affected. But a hot voicecoil will increase Qe and therefore overall Qt will increase until the VC cools down. What you say may be true but the calculation of Vas is dependent on measuring the impedance curve and Fs and Re and Q does change and so do the calculated values of Vas. But, and this is the important point is that they fall back to 'fresh' values as the voice coil cools down. It may be true that this phenomenon may be independent of the latter but the real point is that speakers DO NOT break in. At best it can be said that they may WARM UP. But because performance doesn't change why would anyone care? Vas is not actually determined from the free air impedance curve since it is dependant on Cms, Sd and air density, but that is not the issue here. We, and the others still involved with this issue, are in agreement here that break in as far the drivers themselves are concerned is at best an issue of the past. What is of importance is how the drivers mechanical properties are affected by ambient conditions of which ambient temperature is most critical. Temperature related voice coil compression from overheating is a functional matter that is always relevant. But the affect of ambient temperature on driver characteristics is not insignificant! System compliance varies greatly in the cold and can lead to more than a 10% change in Fs at even 50 deg F. This is why drivers intended for indoor use are developed, and T/S specifications are considered representative, at operating temperatures between 20 and 25 deg C. If one leaves the heat off during the day in an environment with cold winters, this is exactly what is happening. Speakers tend to sound rather lifeless until first the room, then the speakers warm up. Polypropylene cones are especially notorious for extra buckling at higher temperatures. I discovered this myself in turn to hear from driver developers that they have been struggling with this for years. A typical warm summer can cause the living room to heat up to 80 deg F.unless you keep the AC on the whole time. This affects the sound of speakers, especially FR in polypropylene models. The ambient temperature can significantly affect Cms where an increase in temperature increases system compliance and leads to increased Vas and decreased Fs which in turn increases overal Q. So the weather has a greater influence on the mechanical properties of a driver than most other factors. Sure. But that simply says that speakers do not break-in. Agreed Driver break-in is much less of an issue these days mainly because the industry has for awhile now demanded low assembly line unit to unit variability and polymer technology has made this possible. Break in, when present in the driver itself is usually in only in the amount of hysteresis leading to dicernable differences only when the cone is barely moving. Meaning when Theil/Small parameters are generally measured :-) A very common and very audible "break in" phenomena when first taking speakers home is due to external factors. The ambient temperature changes from warehouse to car etc and temporarily changes mechanical compliance. Often a speaker is not stocked in the same orientation as it is used, so that internal damping materials often shift during the first days of use and this can be very discernable. Even the re-location from a different elevation can cause an atmospheric pressure gradient with a sealed midrange driver leading to a break-in phenomena for a few days until equalibrium has been reached. I'm guessing that elevation and storage equibrium is reached within a few seconds. If you have some more data I'd be glad to hear it. Well I'll tell you a story. A customer of mine awhile back lived in Redlands, California (elevation +/- 500 ft) and had a cabin at Big Bear Lake (elevation +/- 6000 ft) that he frequently went to for a few weeks at a time. He had a pair of one the smaller B&W Nautilus speakers to first use the now common stiff larger 6" midrange driver (I don't know the model number). Because he liked these speakers he took them with him every time he went to his cabin. He noticed that they sounded quite bad for a few days until they sorted themselves out. When he contacted me about this, I explained the temperature thing as a hypothesis, and he went to great lengths to correct for this. A neighbor turned on the heat at the cabin a day in advance, he pre-heated the car prior to loading, and he carried them outside wrapped in a couple of sleeping bags. The problem didn't seem to go away. We decided to look inside since he was considering mod's anyway. In one of the speakers, a glob of glue had fallen on the leak hole in the midrange enclosure. Also inspecting the driver and mounting seal, it didn't appear that air was going to get out easily. Once this was removed, the problem went away. This is a little exceptional perhaps but it proves the point Actually it doesn't seem relevant to your point. It seems that you just discovered an operating flaw if anything. The "problem" was exactly what? The speakers didn't sound good for a few days but then started sounding good when you removed the plugged hole? None of this seems relevant to ambient conditions or elevation. Forgive me if I'm missing something here. |
#568
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(Wessel Dirksen) wrote:
(Nousaine) wrote in message ... John Stone wrote: in article , Nousaine at wrote on 7/31/04 4:26 PM: Some vendors will match your drivers for specs for an additional fee, I believe NorthCreek is one of them. And how do they do that? It's been my experience that often the drivers marketed to the DIY market seem to be end-of-run, out-of-spec orr OEM rejected drivers that may not even have the same parts as listed in the catalog. That's OK but they need to be verified not only for T/S parameters but also frequency response. For example I once purchased Dynaudio drivers for a custom powered speaker system. Not only was the Fs of the woofers a half octave higher than advertised they weren't even within 10 Hz of each other. This required significant design compensation. Why do you keep resurrecting this old wives' tale, Tom? It's not an old wive's tale. It's a given experience. And it's one of the reasons that I stopped making speakers,other than subwoofers 10 years ago. Where is your evidence that today's DIY drivers are end run, OEM rejects, or out-of-spec? I don't have any evidence that this is the case other than never having bought a driver from anybody, other than tweeters, that didn't require more investigation than specifications from the vendor for design purposes. My present company (SEAS) and my previous company (Vifa/Scan-Speak) would never allow out of spec drivers to leave the factory-ever. In fact, each SEAS product is fully tested for Fs, frequency response, and rub/buzz before it ever leaves the factory. Anything that goes to a product distributor like Madisound is virtually identical to the same product sold to an OEM. I think you may both be right. John's perspective may be a bit positively skewed because he works for Seas who in my experience have the best unit to unit tolerances in the business. Actually there's pretty much nothing bad you can say about Seas. Focal seem to be consistantly inconsistant with the individual units I've had but not terrible per se, in that the drivers I have had would have still passed reasonable assembly line tolerances compared to published spec's. I have to side with Tom on Dynaudio though. I once had two 17W75's (out of +/- 12 units total) with a spec'd Fs and a Qt of 1.1!! (in comparison to 0.74 with normal Fs and Rdc that represents a magnetic gap flux down close to 50%) I've had 4 20W-75's before of which two of them had an Fs of 55 (almost an octave to high) I've never worked with OEM units from either to know how units from the same series compare. Haven't used enough Scanspeak woofers to know about them either. I've seen some loosey goosey Vifa drivers in my day as well, but I rarely use Vifa woofers anymore so I don't know anymore. In the early to mid 90's, I found that polymer surrounds of several Vifa units got severely stiff in just a few years time in both Southern California and in The Netherlands. Seas drivers don't seem to have this. Actually, about 6 months ago, I got an old project from 1995 back in my hands that had Seas CA21-RE's in them. Because I write the T/S parameters on the magnets of every individual driver I happen to measure, I re-tested this unit and it was still spot on even being tortured in an aggressive bandpass cabinet. A little further up in this thread ambient temperature was addressed as it can certainly affect T/S measurement, so measuring a driver's parameters in a hot or cold garage is asking for surprizes. Actually I'll accpet what Mr Stone says about the drivers his company makes although he never did quantify what he meant by 'virtually' identical to OEM products :-) And it's true that my first hand experience with drivers other than woofers has been limited in the past few years. For those I employ DUMAX which is capable of measuring parameters (including compliance and BL) over a range of excursion. It is quite typical for rest-position measurements to differ quite significantly from manufacturers specifications. The latter may either be estimated from the parts values or measured with nearly no movement of the cone (as originally specified by Small). That's all fine but a speaker is seldom used under the latter conditions. The Theile/Small parameters were originally developed so that engineers could use commonly available test instruments and develop a set of measurements to aid in design. That was the beauty of them. Today we have DUMAX and Klippel measurements that take into account non-linearities of the speaker systems. I'm quite encouraged that manufacturers are now making speakers specifically for the DIY market. My experience with KEF and Dynaudio drivers (like you describe above) led me to believe that the DIY market may have been fed products that that either failed to meet OEM specifications OR were over-runs of OEM lots that may not even have the same parts that may have been specified in the catalog. I may have been in error in that regard and/or perhaps manufacturing techniques (both gluing up speaker products AND in the parts manufacture) have improved so that making the same speaker twice in a row is easier. Although I think that many people think I'm dumping on DIY projects. That's far from the case. But I see no harm in divulging to enthusiasts up front that they are not likely to save money or get demonstrably better performance than they will get by hard shopping. |
#569
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On 17 Aug 2004 23:04:05 GMT, (Wessel Dirksen) wrote:
John Stone wrote in message ... in article , Nousaine at wrote on 8/4/04 7:05 PM: And the better sounding ones cost a lot more in terms of cash outlay. The Thor is around $1500.00. Have you heard it? No. But John Stone reported on the Seas Odin kits he uses; and after checking these on the Madisound website they are actually more expensive than the excellent PSB Stratus Mini. So is this kit. Yes, but are you then assuming that the 2 are qualitatively equal? Let's compare them. The PSB is a 6-1/2 2-way with a Vifa P17WJ 17cm and D19AD 19mm alu dome tweeter. The Odin is a WTW with 2 6-1/2" SEAS Excel woofers and a 25mm "Millennium" soft dome tweeter. At this point John has said enough. This is apples vs. oranges. If both kits are designed reasonably, based on components, the later will tear up the former left, right and sideways. This is like comparing a Saturn to a BMW M5. Quite so - and including the price tags of those vehicles (and those speakers), not unreasonable............ OTOH, if you compare a Saturn 5 with the BMW M5.... :-) -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#570
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(Nousaine) wrote in message ...
(Wessel Dirksen) wrote: (Nousaine) wrote in message ... John Stone wrote: in article , Nousaine at wrote on 7/31/04 4:26 PM: Some vendors will match your drivers for specs for an additional fee, I believe NorthCreek is one of them. And how do they do that? It's been my experience that often the drivers marketed to the DIY market seem to be end-of-run, out-of-spec orr OEM rejected drivers that may not even have the same parts as listed in the catalog. That's OK but they need to be verified not only for T/S parameters but also frequency response. For example I once purchased Dynaudio drivers for a custom powered speaker system. Not only was the Fs of the woofers a half octave higher than advertised they weren't even within 10 Hz of each other. This required significant design compensation. Why do you keep resurrecting this old wives' tale, Tom? It's not an old wive's tale. It's a given experience. And it's one of the reasons that I stopped making speakers,other than subwoofers 10 years ago. Where is your evidence that today's DIY drivers are end run, OEM rejects, or out-of-spec? I don't have any evidence that this is the case other than never having bought a driver from anybody, other than tweeters, that didn't require more investigation than specifications from the vendor for design purposes. My present company (SEAS) and my previous company (Vifa/Scan-Speak) would never allow out of spec drivers to leave the factory-ever. In fact, each SEAS product is fully tested for Fs, frequency response, and rub/buzz before it ever leaves the factory. Anything that goes to a product distributor like Madisound is virtually identical to the same product sold to an OEM. I think you may both be right. John's perspective may be a bit positively skewed because he works for Seas who in my experience have the best unit to unit tolerances in the business. Actually there's pretty much nothing bad you can say about Seas. Focal seem to be consistantly inconsistant with the individual units I've had but not terrible per se, in that the drivers I have had would have still passed reasonable assembly line tolerances compared to published spec's. I have to side with Tom on Dynaudio though. I once had two 17W75's (out of +/- 12 units total) with a spec'd Fs and a Qt of 1.1!! (in comparison to 0.74 with normal Fs and Rdc that represents a magnetic gap flux down close to 50%) I've had 4 20W-75's before of which two of them had an Fs of 55 (almost an octave to high) I've never worked with OEM units from either to know how units from the same series compare. Haven't used enough Scanspeak woofers to know about them either. I've seen some loosey goosey Vifa drivers in my day as well, but I rarely use Vifa woofers anymore so I don't know anymore. In the early to mid 90's, I found that polymer surrounds of several Vifa units got severely stiff in just a few years time in both Southern California and in The Netherlands. Seas drivers don't seem to have this. Actually, about 6 months ago, I got an old project from 1995 back in my hands that had Seas CA21-RE's in them. Because I write the T/S parameters on the magnets of every individual driver I happen to measure, I re-tested this unit and it was still spot on even being tortured in an aggressive bandpass cabinet. A little further up in this thread ambient temperature was addressed as it can certainly affect T/S measurement, so measuring a driver's parameters in a hot or cold garage is asking for surprizes. Actually I'll accpet what Mr Stone says about the drivers his company makes although he never did quantify what he meant by 'virtually' identical to OEM products :-) And it's true that my first hand experience with drivers other than woofers has been limited in the past few years. For those I employ DUMAX which is capable of measuring parameters (including compliance and BL) over a range of excursion. It is quite typical for rest-position measurements to differ quite significantly from manufacturers specifications. The latter may either be estimated from the parts values or measured with nearly no movement of the cone (as originally specified by Small). That's all fine but a speaker is seldom used under the latter conditions. T/S parameters should always be tested at least in the neigborhood of 1/2 Xmax. Earlier we discussed hysteresis, so did John Stone, there may be some break in there. I bang on 'em when I do T/S. Almost full x-max, why not? It is a single sided hysteresis profile these days. I also tend to run em in anyway before measurement. With most it makes no difference at all. Tweeters are different, they do break in but ussualy within 30 minutes or so with high pass filtered pink noise. The Theile/Small parameters were originally developed so that engineers could use commonly available test instruments and develop a set of measurements to aid in design. That was the beauty of them. Today we have DUMAX and Klippel measurements that take into account non-linearities of the speaker systems. I'm quite encouraged that manufacturers are now making speakers specifically for the DIY market. My experience with KEF and Dynaudio drivers (like you describe above) led me to believe that the DIY market may have been fed products that that either failed to meet OEM specifications OR were over-runs of OEM lots that may not even have the same parts that may have been specified in the catalog. I'll tell you what else. I've had Dynaudio units with suspiciously too many stickers on them, I never considered what you are saying. Also, I contacted Dynaudio about the 4 20W-75's I had because I was considering +/- bulk stocking them (for me that means 10 - 20). This is in +/- 1994. And the response was: Our Esotec line is build to such high standards and tolerances that our research has shown that there is no need to measure them on the assembly line. Upon which he dismissed my results as user error and did mention 30 hours of break in. The woofers were very stable though, they stayed at 55 hz after weeks of constant break in. Although the 20W-75's were very good, this didn't take well with me. I may have been in error in that regard and/or perhaps manufacturing techniques (both gluing up speaker products AND in the parts manufacture) have improved so that making the same speaker twice in a row is easier. Although I think that many people think I'm dumping on DIY projects. That's far from the case. But I see no harm in divulging to enthusiasts up front that they are not likely to save money or get demonstrably better performance than they will get by hard shopping. |
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#572
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"Nousaine" wrote in message
... (Wessel Dirksen) wrote: (Nousaine) wrote in message ... "Wessel Dirksen" wrote: "Michael McKelvy" wrote in message ... "Nousaine" wrote in message ... "Michael McKelvy" wrote: ....snip to content...... I don't know why I'd trust anybody that still sells the break-in mythology. :-) compensation. But again, why would I want to trust people who still subscribe to the speaker break-in urban legend? For the same reason I wouln't write off someone who sells finished speakers that tout the fact that they have gold plated terminals, it's about marketing and doesn't really do any harm. I know your position on break-in and my expierience is the same, but it is limited. There is a car speaker company's web site I visited that had specs on before and after break-in on their drivers, there was a difference albeit a small one. I don't have a 'position' on break-in. I've conducted more than one extensive experiment testing the hypothesis. It is true that you can 'measure' changes in Fs and Vas immediately after a long break-in period when the voice coil is still hot. But those changes are 1) off-setting in regard to cabinet design and 2) return to previous values after a few hours rest. Fs and Vas are mechanical properties and have no dependance on the electrical properties of the voicecoil whatsoever. Even if the voicecoil could theoretically double it's Rdc from overheating (impossible without damage), the Fs and Vas and therefore Qm would not be affected. But a hot voicecoil will increase Qe and therefore overall Qt will increase until the VC cools down. What you say may be true but the calculation of Vas is dependent on measuring the impedance curve and Fs and Re and Q does change and so do the calculated values of Vas. But, and this is the important point is that they fall back to 'fresh' values as the voice coil cools down. It may be true that this phenomenon may be independent of the latter but the real point is that speakers DO NOT break in. At best it can be said that they may WARM UP. But because performance doesn't change why would anyone care? Vas is not actually determined from the free air impedance curve since it is dependant on Cms, Sd and air density, but that is not the issue here. We, and the others still involved with this issue, are in agreement here that break in as far the drivers themselves are concerned is at best an issue of the past. What is of importance is how the drivers mechanical properties are affected by ambient conditions of which ambient temperature is most critical. Temperature related voice coil compression from overheating is a functional matter that is always relevant. But the affect of ambient temperature on driver characteristics is not insignificant! System compliance varies greatly in the cold and can lead to more than a 10% change in Fs at even 50 deg F. This is why drivers intended for indoor use are developed, and T/S specifications are considered representative, at operating temperatures between 20 and 25 deg C. If one leaves the heat off during the day in an environment with cold winters, this is exactly what is happening. Speakers tend to sound rather lifeless until first the room, then the speakers warm up. Polypropylene cones are especially notorious for extra buckling at higher temperatures. I discovered this myself in turn to hear from driver developers that they have been struggling with this for years. A typical warm summer can cause the living room to heat up to 80 deg F.unless you keep the AC on the whole time. This affects the sound of speakers, especially FR in polypropylene models. The ambient temperature can significantly affect Cms where an increase in temperature increases system compliance and leads to increased Vas and decreased Fs which in turn increases overal Q. So the weather has a greater influence on the mechanical properties of a driver than most other factors. Sure. But that simply says that speakers do not break-in. Agreed Driver break-in is much less of an issue these days mainly because the industry has for awhile now demanded low assembly line unit to unit variability and polymer technology has made this possible. Break in, when present in the driver itself is usually in only in the amount of hysteresis leading to dicernable differences only when the cone is barely moving. Meaning when Theil/Small parameters are generally measured :-) A very common and very audible "break in" phenomena when first taking speakers home is due to external factors. The ambient temperature changes from warehouse to car etc and temporarily changes mechanical compliance. Often a speaker is not stocked in the same orientation as it is used, so that internal damping materials often shift during the first days of use and this can be very discernable. Even the re-location from a different elevation can cause an atmospheric pressure gradient with a sealed midrange driver leading to a break-in phenomena for a few days until equalibrium has been reached. I'm guessing that elevation and storage equibrium is reached within a few seconds. If you have some more data I'd be glad to hear it. Well I'll tell you a story. A customer of mine awhile back lived in Redlands, California (elevation +/- 500 ft) and had a cabin at Big Bear Lake (elevation +/- 6000 ft) that he frequently went to for a few weeks at a time. He had a pair of one the smaller B&W Nautilus speakers to first use the now common stiff larger 6" midrange driver (I don't know the model number). Because he liked these speakers he took them with him every time he went to his cabin. He noticed that they sounded quite bad for a few days until they sorted themselves out. When he contacted me about this, I explained the temperature thing as a hypothesis, and he went to great lengths to correct for this. A neighbor turned on the heat at the cabin a day in advance, he pre-heated the car prior to loading, and he carried them outside wrapped in a couple of sleeping bags. The problem didn't seem to go away. We decided to look inside since he was considering mod's anyway. In one of the speakers, a glob of glue had fallen on the leak hole in the midrange enclosure. Also inspecting the driver and mounting seal, it didn't appear that air was going to get out easily. Once this was removed, the problem went away. This is a little exceptional perhaps but it proves the point Actually it doesn't seem relevant to your point. It seems that you just discovered an operating flaw if anything. The "problem" was exactly what? The speakers didn't sound good for a few days but then started sounding good when you removed the plugged hole? None of this seems relevant to ambient conditions or elevation. Forgive me if I'm missing something here. Many/most drivers leak air inheirantly from the front to the back of the driver through porous cone material (kevlar) or through a fabric dust cover with vented pole piece etc. Those with phase plugs leak by definition. If a driver doesn't leak, and happens to be air tight mounted in a sealed enclosure (this shouldn't happen), than an atmospheric pressure gradient is possible to maintain between the outside air and the sealed cabinet. I would imagine that most manufacturers provide a small hole to allow equalization. I'm assuming, obviously don't know for sure, that this happened in the one speaker in the example and made the set sound poor. |
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"Nousaine" wrote in message
... (Wessel Dirksen) wrote: John Stone wrote in message ... in article , Nousaine at wrote on 8/4/04 7:05 PM: And the better sounding ones cost a lot more in terms of cash outlay. The Thor is around $1500.00. Have you heard it? No. But John Stone reported on the Seas Odin kits he uses; and after checking these on the Madisound website they are actually more expensive than the excellent PSB Stratus Mini. So is this kit. Yes, but are you then assuming that the 2 are qualitatively equal? Let's compare them. The PSB is a 6-1/2 2-way with a Vifa P17WJ 17cm and D19AD 19mm alu dome tweeter. The Odin is a WTW with 2 6-1/2" SEAS Excel woofers and a 25mm "Millennium" soft dome tweeter. At this point John has said enough. This is apples vs. oranges. If both kits are designed reasonably, based on components, the later will tear up the former left, right and sideways. This is like comparing a Saturn to a BMW M5. Oh for Pete's sake. The finished PSB costs 2/3 of the kit. For an even price comparison, and if you want to play the driver-count game, you can get a pair of fully finished Paradigm Studio 60s for $1500 or a pair of Studio 40s for $1100. Both with full warranties. Everyone wants to ignore that you aren't going to save money or get demonstrably better performance, even with a high quality kit, compared to what's commercially available. Tom, are you sure about that? Are you sure you know what you're comparing here? The last statement could be interpreted as just as presumpuous as thinking there could be no performance difference between a true sportscar and a family sedan. And I understand you review stuff so you'd be a good judge. Have you heard the Seas Milleneum tweeter in a good system in a good listening environment? IMO, if depth of imaging is something you enjoy, I would seriously listen sometime because this tweeter is exceptional. It and a few exotic competitive counterparts are considered to be among the industry's best dome tweeters and as you can see they don't cost a mortgage. You normally find these tweeters (or OEM variants) in goofy priced exotic production speakers. The run of the mill 19mm Vifa isn't in the ballpark. The fact is this kit does not just have regular components, but recognized industry performance exotica and the retail price is for probably about 60% represented in the cost of the components. You just deemed them at par, performance wise, with a $1200 retail product which probably has a production cost in the neighborhood of $250 of which the components probably represent less than a third. Why the difference? You do the sweating yourself and you don't pay for expensive ad's. Even though price doesn't have to say it all, you pretty much still get what you pay for on a large scale (aside from exceptional stupid stuff like 300K amps). I'd bet the farm on this Seas kit over the PSB and I haven't even seen or heard either and I can do this with confidence, not suposition, because the particular PSB in question with good but run of the mill transducers doesn't have a chance in hell to outperform these high end Seas Excel components just as the Saturn doesn't have a chance in hell on the racetrack against an BMW M5. "high-end" speakers that aren't worth the paper the reviews are printed on --- so what? |
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"Nousaine" wrote in message
... "Wessel Dirksen" wrote: ...snip.... Actually it doesn't seem relevant to your point. It seems that you just discovered an operating flaw if anything. The "problem" was exactly what? The speakers didn't sound good for a few days but then started sounding good when you removed the plugged hole? None of this seems relevant to ambient conditions or elevation. Forgive me if I'm missing something here. Many/most drivers leak air inheirantly from the front to the back of the driver through porous cone material (kevlar) or through a fabric dust cover with vented pole piece etc. Those with phase plugs leak by definition. If a driver doesn't leak, and happens to be air tight mounted in a sealed enclosure (this shouldn't happen), than an atmospheric pressure gradient is possible to maintain between the outside air and the sealed cabinet. I would imagine that most manufacturers provide a small hole to allow equalization. I'm assuming, obviously don't know for sure, that this happened in the one speaker in the example and made the set sound poor. Sure but didn't the original condition "change" with the passage of time in either direction? Wasn't the hole plugged all the time? Couldn't it be more likely that the system never changed sound but the listener simply re-adjusted his bias? Why not duplicate this condition? Of course, I understand that this may have occured long ago. Probably unlikely, a small hole will never affect the Qtc of a closed system so glue or no glue, performance is the same. A pressure gradient would always be audible if it existed as it affects the function of the transducer. But in all fairness, I don't know. For all I know the glue didn't even cover the hole enough to abstruct air. The apparent reproducable problem apparently sorted itself out leaving this as a reasonable hypothesis .. I did completely seal a cabinet up with silicon stuff a reeeeal long time ago ( I believe I was 17), and mounted a bike valvestem on the back. I pumped it up and watched the woofer blob out then played Led Zeppelin on it to see what it would sound like. It took about 30 seconds to gradually normalize. I had nothing to measure it with back then but it sounded terrible and slowly came back to life. Hilarious. |
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"Nousaine" wrote in message
... (Wessel Dirksen) wrote: ....snips... T/S parameters should always be tested at least in the neigborhood of 1/2 Xmax. Earlier we discussed hysteresis, so did John Stone, there may be some break in there. I bang on 'em when I do T/S. Almost full x-max, why not? It is a single sided hysteresis profile these days. I also tend to run em in anyway before measurement. With most it makes no difference at all. Tweeters are different, they do break in but ussualy within 30 minutes or so with high pass filtered pink noise. So how do you determine "half" Xmax? Or "full" Xmax? Guestimate when pre-adjusting imput voltage. |
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"Wessel Dirksen" wrote:
"Nousaine" wrote in message ... (Wessel Dirksen) wrote: John Stone wrote in message ... in article , Nousaine at wrote on 8/4/04 7:05 PM: And the better sounding ones cost a lot more in terms of cash outlay. The Thor is around $1500.00. Have you heard it? No. But John Stone reported on the Seas Odin kits he uses; and after checking these on the Madisound website they are actually more expensive than the excellent PSB Stratus Mini. So is this kit. Yes, but are you then assuming that the 2 are qualitatively equal? Let's compare them. The PSB is a 6-1/2 2-way with a Vifa P17WJ 17cm and D19AD 19mm alu dome tweeter. The Odin is a WTW with 2 6-1/2" SEAS Excel woofers and a 25mm "Millennium" soft dome tweeter. At this point John has said enough. This is apples vs. oranges. If both kits are designed reasonably, based on components, the later will tear up the former left, right and sideways. This is like comparing a Saturn to a BMW M5. Oh for Pete's sake. The finished PSB costs 2/3 of the kit. For an even price comparison, and if you want to play the driver-count game, you can get a pair of fully finished Paradigm Studio 60s for $1500 or a pair of Studio 40s for $1100. Both with full warranties. Everyone wants to ignore that you aren't going to save money or get demonstrably better performance, even with a high quality kit, compared to what's commercially available. Tom, are you sure about that? Are you sure you know what you're comparing here? The last statement could be interpreted as just as presumpuous as thinking there could be no performance difference between a true sportscar and a family sedan. Why would that be? I've been a DIY constructor since the early 70s. I've been evaluating speakers professionally since 1985. And I understand you review stuff so you'd be a good judge. And? Have you heard the Seas Milleneum tweeter in a good system in a good listening environment? IMO, if depth of imaging is something you enjoy, I would seriously listen sometime because this tweeter is exceptional. It and a few exotic competitive counterparts are considered to be among the industry's best dome tweeters and as you can see they don't cost a mortgage. You normally find these tweeters (or OEM variants) in goofy priced exotic production speakers. The run of the mill 19mm Vifa isn't in the ballpark. The fact is this kit does not just have regular components, but recognized industry performance exotica and the retail price is for probably about 60% represented in the cost of the components. What "kit" do you reference? You just deemed them at par, performance wise, with a $1200 retail product which probably has a production cost in the neighborhood of $250 of which the components probably represent less than a third. Why the difference? What differennce? Are you suggesting that the distributor and the manufacturer of speaker 'parts' don't need a mark-up? Are you suggesting that an individual buying parts 2 pieces at a time has some economic advantage? You do the sweating yourself and you don't pay for expensive ad's. Sure; but you also don't get to buy parts at OEM prices OR get to make then yourself and eat the supplier margin. Even though price doesn't have to say it all, you pretty much still get what you pay for on a large scale (aside from exceptional stupid stuff like 300K amps). I'd bet the farm on this Seas kit over the PSB and I haven't even seen or heard either and I can do this with confidence, not suposition, because the particular PSB in question with good but run of the mill transducers doesn't have a chance in hell to outperform these high end Seas Excel components just as the Saturn doesn't have a chance in hell on the racetrack against an BMW M5. I'm glad you are willing to 'bet the farm' on systems that you've never heard :-) "high-end" speakers that aren't worth the paper the reviews are printed on --- so what? So what? |
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"Wessel Dirksen" wrote:
"Nousaine" wrote in message ... (Wessel Dirksen) wrote: ....snips... T/S parameters should always be tested at least in the neigborhood of 1/2 Xmax. Earlier we discussed hysteresis, so did John Stone, there may be some break in there. I bang on 'em when I do T/S. Almost full x-max, why not? It is a single sided hysteresis profile these days. I also tend to run em in anyway before measurement. With most it makes no difference at all. Tweeters are different, they do break in but ussualy within 30 minutes or so with high pass filtered pink noise. So how do you determine "half" Xmax? Or "full" Xmax? Guestimate when pre-adjusting imput voltage. So you're measuring T/S parameters based on "estimates" of stroke? How do you compile that with estimates of performance? |
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Dick Pierce wrote in message ...
(Nousaine) wrote The Theile/Small parameters were originally developed so that engineers could use commonly available test instruments and develop a set of measurements to aid in design. No, they were not. The Thiele-Small parameter set was developed as a means of representing diverse parameters, such as acoustical vs mechanical compliance, with a common set of units. A second reason was to allow the representation of the system description in the language of filter synthesis, thus the use of "Q" values for describing mechanical, electrical and acoustical loss mechanisms. An example of the almost tower of Babel units confusion is that of compliance. The unit for mechanical compliance, Cm, is pretty straight- forward and familiar to anyone having taken college freshman-level physics: it described in terms of displacement per unit force, and in units of meters per newton. On the other hand, acoustical compliance is not so neat and obvious: it's expressed in units of meters^4 seconds^2 per kilogram! Now, quick, what's the effect of the parallel mechanical combination of a mechanical stiffness with an acoustical stiffness? Instead, what Small did was come up with a system-description relevant unit: equivalent volume of compliance, Vas. This basically transforms the mechanical compliance of the driver into a volume. It's MUCH easier to calculate the effect of putting a mechanical compliance in parallel with an acoustical compliance when both are stated in the same units: volume. One can quickly see that a drive with a Vas of 50 liters placed in a box with a volume of 50 liters will result in a total system compliance of 25 liters. All of the primary T/S parameters, Vas, Fs, Qms, Qes, Qts Vb, Qb and so forth incorporate ALL of the fundamental mechanical and acoustical para- meters of the system in a representation that makes the DESCRIPTION of the system make sense in a system filter notation. One talks about the Q of a high-pass electrical filter in precisely the same way that one talks about the Q of a woofer system. It had NOTHING to do with "commonly available test equipment." Indeed, the equipment needed to measure the T/S parameter set is no more or less common that that needed to measure the electromechanical parameter set. In fact, one can measure the electromechanical properties almost directly using LESS equipment. For example, the entire electromechanical property set can be measured without using ANY AC signals. (How, one might wonder, does one find the resonance without an AC signal? Well, if one knows the mass, and one knows the compliance, and one can multiply and take square roots and reciprocals, you're there. Oh, and you have to know pi to a decimal place or three). Agreed Dick if you happen to know Mms, but what if you don't know anything about a driver and don't want to guess. Cms can be determined statically with the added mass - cone displacement method, but how would you then determine Mms without an AC signal. Is there something I'm missing. You have to know at least 2 of the 3, fs, Cms, or Mms. That was the beauty of them. The T/S model has EVERYTHING to do with coherent, consistent SYSTEM description. And THAT'S it's real beauty: describing speakers NOT as a collections of parts, but as an inter-related SYSTEM having a SYSTEM RESPONSE FUNCTION. |
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For example, the entire electromechanical property
set can be measured without using ANY AC signals. (How, one might wonder, does one find the resonance without an AC signal? Well, if one knows the mass, and one knows the compliance, and one can multiply and take square roots and reciprocals, you're there. Oh, and you have to know pi to a decimal place or three). Agreed Dick if you happen to know Mms, but what if you don't know anything about a driver and don't want to guess. Cms can be determined statically with the added mass - cone displacement method, but how would you then determine Mms without an AC signal. Is there something I'm missing. You have to know at least 2 of the 3, fs, Cms, or Mms. Well, there's always the direct method: weigh the cone. That certainly works well in my situation where I'm given a dozen samples to evaluate and can sacrifice several of them during a tear-down. These days, mass is among the most tightly controlled proproties of the cone: you measure one, you've measured them all. Alternatively, once you've determined Cms as you describe (and, by the way, with a variable DC power supply, you also determine Bl by injecting a current sufficient to restore the cone back to its rest position), you can measure mass by measuring the deflection with the axis vertical, invert the driver, measure it again, and calculate the mass from the deflection and compliance. But, more to the point, the T/S parameter set didn't come about as a means of making measurements convenient. -- +--------------------------------+ | Dick Pierce | | Professional Audio Development | +--------------------------------+ |
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"Nousaine" wrote in message
... "Wessel Dirksen" wrote: "Nousaine" wrote in message ... (Wessel Dirksen) wrote: ....snips... T/S parameters should always be tested at least in the neigborhood of 1/2 Xmax. Earlier we discussed hysteresis, so did John Stone, there may be some break in there. I bang on 'em when I do T/S. Almost full x-max, why not? It is a single sided hysteresis profile these days. I also tend to run em in anyway before measurement. With most it makes no difference at all. Tweeters are different, they do break in but ussualy within 30 minutes or so with high pass filtered pink noise. So how do you determine "half" Xmax? Or "full" Xmax? Guestimate when pre-adjusting imput voltage. So you're measuring T/S parameters based on "estimates" of stroke? How do you compile that with estimates of performance? This is not a big deal. Once you get beyond the hysteresis of the suspension then it's all the same if you don't overcook it. If the data sheet says 6mm of Xmax, then as a rule of thumb I see if it moves about this much during the setup prior to actually measuring. It's the electro/mechanical properties you are measuring here which are inheirant attributes and do not change with displacement. |
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"Nousaine" wrote in message
... "Wessel Dirksen" wrote: "Nousaine" wrote in message ... (Wessel Dirksen) wrote: John Stone wrote in message ... in article , Nousaine at wrote on 8/4/04 7:05 PM: And the better sounding ones cost a lot more in terms of cash outlay. The Thor is around $1500.00. Have you heard it? No. But John Stone reported on the Seas Odin kits he uses; and after checking these on the Madisound website they are actually more expensive than the excellent PSB Stratus Mini. So is this kit. Yes, but are you then assuming that the 2 are qualitatively equal? Let's compare them. The PSB is a 6-1/2 2-way with a Vifa P17WJ 17cm and D19AD 19mm alu dome tweeter. The Odin is a WTW with 2 6-1/2" SEAS Excel woofers and a 25mm "Millennium" soft dome tweeter. At this point John has said enough. This is apples vs. oranges. If both kits are designed reasonably, based on components, the later will tear up the former left, right and sideways. This is like comparing a Saturn to a BMW M5. Oh for Pete's sake. The finished PSB costs 2/3 of the kit. For an even price comparison, and if you want to play the driver-count game, you can get a pair of fully finished Paradigm Studio 60s for $1500 or a pair of Studio 40s for $1100. Both with full warranties. Everyone wants to ignore that you aren't going to save money or get demonstrably better performance, even with a high quality kit, compared to what's commercially available. Tom, are you sure about that? Are you sure you know what you're comparing here? The last statement could be interpreted as just as presumpuous as thinking there could be no performance difference between a true sportscar and a family sedan. Why would that be? I've been a DIY constructor since the early 70s. I've been evaluating speakers professionally since 1985. Geez Tom, so you obviously know alot about this; so I don't quite get your angle on a few of the last replies here. I'm sure you've got knowledge to share here and yet instead of clarifying your views, you seem to diffuse them. Please expand on why . . . "you aren't going to save money or get demonstrably better performance, even with a high quality kit, compared to what's commercially available". This is a powerfully stated generalization. I feel it's usually the other way around but anything's possible on a case to case basis. The Seas kit vs. PSB comparison in question here is especially poignant, indicated in the detailed comparison John Stone made. I put in my rather strongly stated opinion that the enormous performance difference of the drivers (joe blow vs. top of the trade) should be enough to demonstrate with a good amount of certainty the kit as the beter performer. I understand that you're not in agreement. So what's your opinion on the total package vs.driver performance issue? And I understand you review stuff so you'd be a good judge. And? Have you heard the Seas Milleneum tweeter in a good system in a good listening environment? IMO, if depth of imaging is something you enjoy, I would seriously listen sometime because this tweeter is exceptional. It and a few exotic competitive counterparts are considered to be among the industry's best dome tweeters and as you can see they don't cost a mortgage. You normally find these tweeters (or OEM variants) in goofy priced exotic production speakers. The run of the mill 19mm Vifa isn't in the ballpark. The fact is this kit does not just have regular components, but recognized industry performance exotica and the retail price is for probably about 60% represented in the cost of the components. What "kit" do you reference? The one John Stone was comparing to the Seas Odin awhile back. You just deemed them at par, performance wise, with a $1200 retail product which probably has a production cost in the neighborhood of $250 of which the components probably represent less than a third. Why the difference? What differennce? Are you suggesting that the distributor and the manufacturer of speaker 'parts' don't need a mark-up? Are you suggesting that an individual buying parts 2 pieces at a time has some economic advantage? Not at all. But there are more factors involved that make it a sort of "forest for the trees" thing. The advantages of lower costs for materials are far outweighed by the non-material costs to manufacture, market, and retail a hi-fi loudspeaker. Less than half of the total manufacturing cost of a loudspeaker comes from materials. Costs to construct those components into a product (labor) is the largest manufacturing expenditure, but that's often not even the biggest portion of the pricetag. The retailer demands a sizeable portion for his effort on top of that. In the end the actual cost to manufacture a loudspeaker is in the neighborhood of 20 to 25% of MSRP. Considering that DIY has become a large enough industry which can also OEM purchase, kits are ussually cheaper than the sum of all parts sold independantly which eases DIY retail prices somewhat. What is important is how good the kits are designed. I would like to think that the big manufacturers have the advantage of superior expertise on their side and would know how to take a good idea far. It seems that DIY has followed the market but does less so these days. You do the sweating yourself and you don't pay for expensive ad's. Sure; but you also don't get to buy parts at OEM prices OR get to make then yourself and eat the supplier margin. Even though price doesn't have to say it all, you pretty much still get what you pay for on a large scale (aside from exceptional stupid stuff like 300K amps). I'd bet the farm on this Seas kit over the PSB and I haven't even seen or heard either and I can do this with confidence, not suposition, because the particular PSB in question with good but run of the mill transducers doesn't have a chance in hell to outperform these high end Seas Excel components just as the Saturn doesn't have a chance in hell on the racetrack against an BMW M5. I'm glad you are willing to 'bet the farm' on systems that you've never heard :-) "high-end" speakers that aren't worth the paper the reviews are printed on --- so what? So what? |
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"Dick Pierce" wrote in message
... For example, the entire electromechanical property set can be measured without using ANY AC signals. (How, one might wonder, does one find the resonance without an AC signal? Well, if one knows the mass, and one knows the compliance, and one can multiply and take square roots and reciprocals, you're there. Oh, and you have to know pi to a decimal place or three). Agreed Dick if you happen to know Mms, but what if you don't know anything about a driver and don't want to guess. Cms can be determined statically with the added mass - cone displacement method, but how would you then determine Mms without an AC signal. Is there something I'm missing. You have to know at least 2 of the 3, fs, Cms, or Mms. Well, there's always the direct method: weigh the cone. That certainly works well in my situation where I'm given a dozen samples to evaluate and can sacrifice several of them during a tear-down. These days, mass is among the most tightly controlled proproties of the cone: you measure one, you've measured them all. Alternatively, once you've determined Cms as you describe (and, by the way, with a variable DC power supply, you also determine Bl by injecting a current sufficient to restore the cone back to its rest position), you can measure mass by measuring the deflection with the axis vertical, invert the driver, measure it again, and calculate the mass from the deflection and compliance. Indeed, hadn't thought about that one. Certainly fun from a theoretical standpoint although not very practical. Probably wouldn't have enough displacement resolution with a smaller Cms though. But, more to the point, the T/S parameter set didn't come about as a means of making measurements convenient. -- +--------------------------------+ | Dick Pierce | | Professional Audio Development | +--------------------------------+ |
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