thoppa Posted March 4, 2007 Author Share Posted March 4, 2007 Massively simplified. My HF is doing this : HP-HP-HP-AMP-(LP-LP pwm filter)-HP My LF is doing this : LP-LP-HP-AMP-(LP-LP pwm filter) Relative Phase change HF = HP HP HP = +135 LF = LP LP = -90 It's close to 180 so I expected to have to swap the tweeter cables around but I think Klipsch may already have wired it this way. Either that or my amp is inverting somehow...odd. But in any event I have to give this up - as said it is a complex bit of engineering and although I'd like to try to get a full 180 shift for both channels, I'll worry about this 'little' problem another time.... Quote Link to comment Share on other sites More sharing options...
Spkrdctr Posted March 5, 2007 Share Posted March 5, 2007 A simple answer is to not worry about it. Play with it if you want to as a fun exercise, but for real listening, just don't even think of it. There are so many things we can measure that have little to no effect on actually listening to music that you can disregard it. Having been involved in double blind studies, there is almost nothing you can do in a "normal" situation to change the sound. 99% of it is in the mind..... The speaker design itself, (size of drivers, design of driver, box design etc) have far more effect than most anything else. You can even fool most of the people most of the time like Bose does. They succeed because it is so easy to fool the brain. I could go on but, I think you get my point. The brain gets in the way of most improvements........... Quote Link to comment Share on other sites More sharing options...
thoppa Posted March 6, 2007 Author Share Posted March 6, 2007 Hi, Yes, I agree - some differences are clear, some can be measured but it seems to me that others are such a finesse that it is more psychological than anything - my optical cable is an example - will a glass one really sound better than a good polymer fibre ? Hmmm.... I've been using the software recommended by Dr Who to do sweep tests of the frequency response. (Thanks Mike !!!) It has confirmed that my ears are pretty good - phew ! [] The response is reasonably flat across the range of frequencies I'm toying with (700Hz - 3750Hz) plus I've filled in a couple of holes and improved a lot on the original reproduction. It's amazing how much spatial stereo info there is in the upper mid-range so getting tis right has improved the sound field. The original (side-by-side against my bi-amped one) now sounds a hollow and 'dry' in the mid-range and lacks the top-end crispness and clarity I have now. Forget comparing the bass - the original is so muffled by comparison it's immediately obvious. I would say this is a clear benefit of connecting the amps straight to the woofers. Overall the caps are still settling in too so the sound should only get better. I've got it running 24hrs as I'm so impatient to get it all settled ! Apparently, M-Cap silver/oil can take a couple of weeks... As you say, much of the rest is dependant on things I cannot change. I'm now just going through my music collection listening to instruments and voices to find problems that can help me tweak resistor values. If only I didn't have to work..... RF-52 have dips at 1.3Khz and 4.5khz that don't seem to be curable but also don't seem to affect the reproduction.The deep bass region looks more like a couple of camels backs than a smooth response but again, it sounds good. When I finish, I'll post the setup info so anyone doing their own mods to RF52 has somewhere better to start than the original crossover. Cheers, Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 7, 2007 Share Posted March 7, 2007 Are you measuring the acoustical output of your speakers too? Or just the response of the filters? I'm curious how you calibrated everything and what microphone you're using. Quote Link to comment Share on other sites More sharing options...
thoppa Posted March 7, 2007 Author Share Posted March 7, 2007 Hi, I'm only doing the acoustic output of the speakers simply because I prefer to try to tweak this way. I must admit that I'm using a crappy condenser mic from a handsfree car kit because my good dynamic doesn't work with my soundcard. The software allows mic calibration by selecting the measure tab and a mic test response ( after already setting up the sweep test signal from the resource tab ) and then selecting this in calibration from the options tab. As I'm really only interested in the range over the crossover I don't think I need a better mic anyway. It isn't accurate enough to publish the results with any authority but it does confirm what I'm hearing and helps me consider improvements. So now I can simply change a resistor value, listen, do a sweep test to check and then work out the next change. Easy... I have abandoned the Klipsch crossover 'model'. It gives a flat response but doesn't sound as warm or as detailed. I am now using 24dB per octave for the tweeter to run it as low as possible before the horn resonance kicks in and it screams at me. The woofer is a bigger challenge. There is a fixed dip in response at 1.3Khz - just below the crossover - and it rings a bit at just below that frequency too. I'm using 18dB for this. So far I have managed to get pretty smooth roll offs but more testing and fine tweaking is needed. I'm sure I'll come to the point of 'best compromise' soon......... cheers, Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 8, 2007 Share Posted March 8, 2007 Very cool One thing you might look into is REW: http://www.hometheatershack.com/roomeq/ It's a bit more powerful for doing frequency response measurements by allowing you to gate the impulse response so that you can nullify any influences from the room/mic position...essentially giving you an anechoic response in a normal room by sacrificing a little accuracy. Quote Link to comment Share on other sites More sharing options...
thoppa Posted March 8, 2007 Author Share Posted March 8, 2007 Yes - a very cool tool ![H] Thank you so much for directing me to it. I have found that it has really helped me quantify problems and measure minute changes. Of course, my room acoustics etc are messing up the overall measurements but as a relative test it has quickly become essential ! Thanks ! I might move on to the roomeq in due course....when I next get the itch to tweak... [] Cheers Quote Link to comment Share on other sites More sharing options...
thoppa Posted March 8, 2007 Author Share Posted March 8, 2007 Here is a screenshot of the bass driver only - no XO - using my Onkyo. As you can see , spikey ! But it still helps with relative changes.... Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 11, 2007 Share Posted March 11, 2007 You need to find a way to set the window on your FFT so that you can see the response without the influence of the room. Quote Link to comment Share on other sites More sharing options...
thoppa Posted March 13, 2007 Author Share Posted March 13, 2007 Yes indeed - my room is very bad...there's a huge concrete beam where a wall used to be that I swear is causing a mid-bass resonance.... But actually I have now finished tweaking. All done. Just enjoying the music and the satisfaction of a job done, for now...[] Thanks for your help ! It really is much appreciated. That software probably saved me weeks and a small fortune in resistors and caps. Cheers, Tom Quote Link to comment Share on other sites More sharing options...
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