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Dear all,


Stage 2 crossover upgrade V0.23:  Tweaking the 2.5-way design with measurements.


So I have built up my second 2.5 way crossover. I made a few minor changes to the layout this time:

  • added back a series resistor to shape the tweeter response a little;
  • I kept the impedance smoothing section made up of C4 and R4 on the main board;
  • added a positive binding post; and
  • relented and unwound a second 3.5 mH inductor to make up my missing 2mH.


Here's the tweeter and upper woofer board....




For my 0.5 section or lower woofer board I tried using one of the deconstructed crossover PCB's that I now have many of after harvesting all my LCR parts. This worked out great and simplified the wiring to the lower woofer which now takes a negative lead from the main board negative binding post. I have used two 5.6mH inductors in series to get my 6db roll off for the lower KG woofer....





So the KG pair are installed back into my main listening room and I've had a few weeks to enjoy them and I am happy to report that they do indeed sound AMAZING!


The first listening impression I got was a sense of a big step up in the clarity of the midrange. Vocals really shine through where before these seemed more recessed. With this clarity comes a deeper level of richness in many kinds of music that I don't think was there previously. I really wish I had another pair that I could A/B with, original crossovers to new 2.5ways, but I don't so I'm relying on memory, and all of that sense's frailty.


After some time I began to realise just how revealing of the recording quality this design is, and after a while I began to think I wanted to round off the treble just a smidge because I really do like just a bit of warmth, which I think makes medium to loud listening more enjoyable. 


So I went back to XSim and came up with a very minor tweak I'm calling my 2.5way V0.23. This adds a single series resistor R2 to the tweeter (S1m) circuit. I modelled and installed a 5 ohms unit....


This additional resistor has the effect of just slightly tilting the top end downward, softening the very high frequency treble....




R2 is highly tunable, here is the effect of R2 @ 10 ohms.....




Here is R2 @ 3.3 ohms....




Feel free to tune R2 to taste, there is no right or wrong here, as Troels Gravesen says:


"Some call the voicing of speakers an art. I don't think so. Voicing a speaker is a matter of taste like adding spices to a stew. Some like it hot, creamy or crunchy - some don't." 


For completeness I wanted to show some measurements. These were all done in my lounge this time. The only change to the position of my speakers where I normally have them when listening is that I moved the right hand speaker out into the room a little so that the front driver baffle just clears my nice cabinet and DIY 15" Alpine sub.


Despite being far from an ideal measuring environment I think the results are great. Biased? Yes, probably! At least the data allows for some objectivity.  Here's how I measured....




I didn't carefully measure 1 meter away from the cabinet front this time. I just set the mic height by putting it right up to the centre of the tweeter and then pulled the mic stand back roughly 1m and measured.....





Results -  +/- 2db

Here's the left and right comparison, pretty well dead on match for frequency response. I level matched these by knocking 2db off the right enclosure. The right speaker measured a bit louder due in part to the imprecise distance I measured each speaker from and because the left speaker is placed out in what is almost 2 Pi (free standing) space adjacent to the intersection of my lounge/kitchen/dining room compared to the right enclosure being in 0.5 Pi (corner) loading....





Zooming in I think that we might safely call this a 2db +/- result? That sharp dip between 800 and 900 hz is room related, it isn't a feature in any of my outdoor measurements ....





Distortion measurement - a comparison

Wayne Parham at Pi Speakers has published various system and horn/driver combo frequency measurements that make for an interesting comparison.


His Pi H290C waveguide with a B&C DE250 have measured distortion just over 30db down.....

  • Black = measured frequency response (also known as the fundamental).
  • Blue= 2nd harmonic;
  • Pink = 3rd harmonic.





For comparison here is the distortion sweep of the KG's. Note that the output level was running at 90db which is quite loud and indicative of where I'd listen when the family are out.

  • Black = measured frequency response.
  • Red = 2nd harmonic;
  • Purple = 3rd harmonic.




I'm prepared to say the KG's are a very clean, low distortion system with the fundamental better than 40db above measured distortion.  Way to go Klipsch!

This graph also shows the KG's are solid down to 30hz measured like this. 


Based on this data I'd like to venture to anyone that says the KG's are just speakers for teenagers and rockers should rethink everything they thought they knew about them.  I believe this shows conclusively the 5.5's can be extremely fine speakers, by any measure.  :emotion-14:


So, I'm going to keep listening some more with this crossover design in place, I'm really enjoying it and feel that for me, the 5 ohms R2 on the tweeter hits a smooth, rich, balanced listen. 


Hooked up to my new, secondhand, cleaned up AX-570 (which just quietly kills my brand new Onkyo TX-RZ3100 (Pioneer SC-LX901 in a different skin!) hooked up to my KG's in my room) the bass is super articulate and authoritative. Midrange so clean and clear, treble sweeeeeet mmmmm!  :P






I think we have a winner here. The KG's continue to reward.  The journey continues!


Cheers.  :emotion-22:

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Just wanted to say thanks again for the time and effort you put in to improving your speakers and the benefit it will give anyone who looks over what you've done and decides to apply a similar tactic. I am still having those "I can't believe the sound I am hearing from my speakers!" moments! It's amazing what 2 10-ohm resistors did.


Another thing I noticed: I use the chromecast audio streamer to stream Amazon music over wi-fi. The bass and treble controls on the chromecast operate on the digital level so I believe they can be considered DSP level controls. Well, before adding the resistors, I was less than happy with the changes made by adjusting those controls. The music always sounded worse. After adding the resistors, the changes I make to bass and treble through the chromecast audio dongle make meaningful changes to music lacking a bit of high-or-low-end fidelity. The music quality does not suffer, which is supposed to be what DSP is all about. Some talk of DSP as the cure to all woes, but now I think it can work either way; improvements in passive circuits can make all the difference, even to DSP.

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They're some nice speakers alright... some nice discovery..

OP has done a lot of work...


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