Sol
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Post by Sol on Dec 26, 2008 18:26:04 GMT
... if one were thinking about swopping out the tweeters of a your existing speakers, other than dimensions, what's to consider? Can you simply swop out, or would one need to mess with crossovers etc?
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Sol
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Chief Technical Numpty
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Post by Sol on Dec 27, 2008 7:58:17 GMT
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rickcr42
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Post by rickcr42 on Dec 27, 2008 19:38:39 GMT
1-Check the power handling.You don't want or need blown tweeters 2-Sensitivity ratings-too high and you will need to pad it down,too low and you will need to pad down the midrange/midwoofer 3-Crossover point:You really want a broad overlap here if you want to avoid suckouts or again,blown tweeters from trying to keep up with the woofer.If the range is "marginal" then you will need to go to a steeper slope of the HPF but if you do you need to keep in mind that -6dB,-18dB and -24 dB XOs are non inverting while the -12dB filters invert phase so you need to watch your driver polarities and swap red with black when/if you must (some tweeters SOUND better inverted ) 4-Dispersion:The woofer and tweeter WILL have an overlapping range and if too dissimiliar in that region on the dispersion spec you will end up with a confused image.Yes a cone low frequency transducer is totally different than any of the typical tweeter sound generators and why "steps" are usually taken either electrically (The XO) or mechanically (tweeter distance from woofer/tweeter front to back depth) or BOTH to make the region appear seamless at the listening position in the better systems Speaker systems are about the least Plug 'N Play audio device you will come across in a domestic sound system
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Deleted
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Post by Deleted on Dec 27, 2008 20:20:09 GMT
Sol I agree with Rick. Unless you REALLY know what you are doing, it's best to not even go there, if the speakers are already high quality. (and the speakers you mentioned are) With el cheapo speakers you don't have much to lose ! If you have the money, you could always extend their range by sitting a pair of LCY Audio 100kHz Super Tweeters on top. There would then be no need to make any changes to your speakers. SandyK
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Dec 27, 2008 20:47:02 GMT
.....but be aware if you use a NOS DAC without any anti-alias filters (and by the nature of being "NOS" no digital filtering) there is the potential for tweeter failure when it tries to reproduce the inaudible but still present ultrasonic frequencies produced by the DAC.
Like with analog discs or AC hum and woofer cone excursion of "sub-audible" tones the amp will power any signal within its bandwidth range but in the case of a delicate tweeter it is not amplifier power robbing or woofer distortion at stake,woofers mostly being high power devices,but tweeter self destruct if you play above conversation levels and/or over a very long time period (heat build up) as the tweeter treats the above human hearing but within the range of the 100khz tweeter "notes"
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Deleted
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Post by Deleted on Dec 27, 2008 20:59:19 GMT
Rick Sol uses an X-DAC V3, and my answer was in the main directed at him. As far as the scenario you mentioned, it wouldn't be doing too much good for the preamplifier or amplifier either ! However, some people think they know much more than the original designers, even in some cases having the DAC directly drive the output cable, which it was very obviously not designed to do ! SandyK
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Dec 27, 2008 23:50:38 GMT
Actually the signal is harmless to both line level and speaker level circuits since a wideband design will treat it as any other signal with the only possible downside of widebandwidth full class-A maybe working harder to cast off the additional heat,if the audio stage is an unstable design which would respond badly then cast all manner of non linear distortions down into the audible region (easily corrected by adding a low pass filter just below the offending frequency) and if the design is one that provides a natural rolloff,such as one using signal path audio transformers,there is zero risk. Speakers and headphones on the other hand WILL reproduce the signal if it falls within their response band with those that do usually falling into the supertweeter/ES Headphone arena which both of sadly are pretty damn delicate to begin with and while it is the ultra-high bandwidth that makes them items of interest to begin with it is at the same time the very mechanism that can lead to failure if pushed hard outside the norms of audio frequencies for any extended periods (again-HEAT buildup with no means to radiate it out of the voice coil ) that the case here is a "standard" DAC does not mean that in the future this could change (current fad ;D ) or that others so moved to add a supertweeter should not be aware of the possibles
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Deleted
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Post by Deleted on Dec 28, 2008 0:39:50 GMT
Rick In my previous reply " it wouldn't be doing too much good for the preamplifier or amplifier either !" I wasn't meaning that damage would result. I meant that performance would be degraded in the majority of cases. Not all designs would be too happy with digital artifacts at relatively high levels. My heart bleeds for those who are stupid enough to bypass the anti alias filters, then blow up their tweeters ! SandyK P.S. By all means install a higher performing analogue output stage, but don't shove all that crap into the output cables. It also then does not comply with (in the U.S.A.) the relevant FCC standards.
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Dec 28, 2008 2:48:03 GMT
Me once. Until I had a test bed "proof of concept" DAC that I could use as the control and another identical DAC in stock form making the test one with validity since any changes were with a known control to refer back too with the only REALLY hard part being the abi;ity to distinguish what was actualy better and what just different. I ended up keeping the 8x OS digital filter but losing the original Vout-to-opamp anti-alias filter/gain stage going instead to a passive resistor IV stage (simple snip of the pcb trace ) which in turn goes to an external SE 6GM8/WOT "box" to provide the additional gain needed as well as a simple rolloff above 80khz via the trafos thus protecting any sensitive transducers from harm. Yes NOS DACs can sound great but so too can OS DACs and in my case the OS DAc sounder better than the NOS DAC and that using identical DACs (AD1851 based DITB). BUT ! If you don't bother having an upper frequency cutoff in the analog section why bother with the digital filter at all since its sole purpose is to allow one to move the anti-alias filter from one that needs to have its F3 at 20khz (1/2 the 44.1 khz sample rate),which WILL have an effect in the below 20khz range even IF a single pole filter to one that can be moved to a happy medium point that filters out ultrasonics but has no effect below 20khz. a bit off topic but something to consider when you plan to lay down a boatload of loot for a specialized part (good super tweeters are not cheap ;D ) only to find later it is a costly mistake to do so when you light it up
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Sol
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loves motorcycles !
Chief Technical Numpty
Posts: 135
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Post by Sol on Jan 2, 2009 9:58:27 GMT
I've read all that ... and while I don't understand all of it ... I get the sentiment. Don't bother if you want an easy life!
Thanks guys ... I'll take a look at the supplemental super tweeters approach!
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Deleted
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Post by Deleted on Jan 2, 2009 10:33:38 GMT
Sol The LCY 100KHZ Super Tweeters cost >US$500 a pair ! Alex
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Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
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Post by Sol on Jan 3, 2009 16:15:40 GMT
Sol The LCY 100KHZ Super Tweeters cost >US$500 a pair ! Alex Feck! At old exchange rates that would have been possible ... but at current rates I think I'll pass - or keep an eye on fleabay!
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