Khorn Type A / CT-120 / 4500Hz thoughts

[codewritinfool]

Earlier today I modified my Type A Khorn crossovers to support the 4500Hz CT-120 crossover point.  I did it in such a way that I could nearly instantly A/B original/4500Hz by using a DPDT switch to introduce an additional 2uF capacitance in parallel with the 2uF tweeter cap and also a 500uH inductor into the squawker path.  Note that you CANNOT perform this test while using the stock K77; as others have pointed out, it cannot handle the additional power supplied to it by the increased bandwidth.

 

My listening choices were three very familiar tracks (to me, anyway)

Steven Wilson - Hand. Cannot. Erase. - Track 1 : First Regret / 3 Years Older

Nidarosdomens jentekor & TrondheimSolistene - MAGNIFICAT - Track 4 : Et misericordia

Nidarosdomens jentekor & TrondheimSolistene - MAGNIFICAT - Track 5: Fecit potentiam

 

I can definitely hear a difference in the midrange when I A/B the mods.  Quite a lot of the harshness in the midrange is greatly reduced.  This is most apparent to me in the female vocals on Track 5 of MAGNIFICAT.

 

I liked it so much that I listened to a few hours of Steely Dan, Ozric Tentacles, Bucky Pizzarelli, and Animals as Leaders... after which I stopped the A/B and made the mods more permanent.

 

For those interested in the diagram, I can provide it as a PM on request.

[Wirrunna]

codewritinfool, after installing CT-120 tweeters from Bob Crites I recently swapped out my AK3 crossovers on my 1990 KHorns in favour of a home built ALK Universal at 4500Hz. I used the AP12 AK3 variant that utilises the AK3 woofer components.

I too found the midrange harshness greatly reduced and also believe there is a better defined soundstage making it easier to locate instruments and performers.

I only listen at soft levels, rarely do peaks exceed 90db on my sound level meter in a largish damped room.

[ricktate]

Glad to hear that....I did mine years ago with out A/B them. I figured if Bob said it was better it had to be. Plus I liked taking some of the load off the midrange driver. Doesent everone like a little less load on their backs,,lol

[garyrc]

On 8/27/2016 at 3:28 PM, codewritinfool said:

Note that you CANNOT perform this test while using the stock K77; as others have pointed out, it cannot handle the additional power supplied to it by the increased bandwidth.

 

True, but, with a steep slope crossover, like Klipsch uses on the newer Khorns (with a Klipsch AK-4 or AK-5 balancing network), stock K-77s do just fine crossing over at 4,500 Hz..  The EV T35, which is what the K77 is based on, have been crossed over by EV at 3,500 Hz from the 1950s to about the late 1980s.  The crossovers EV used for this were 12 dB per octave, I think.  I have AK-4 crossovers, and there is less midrange harshness with it (or virtually no harshness on many CDs, most SACDs & DVD-As, and, so far, all Blu-rays with dts-HD Master Audio or Dolby True HiFi.

 

[garyrc]

On 8/27/2016 at 3:28 PM, codewritinfool said:

...  Note that you CANNOT perform this test while using the stock K77; as others have pointed out, it cannot handle the additional power supplied to it by the increased bandwidth.

 

True, but, with a steep slope crossover, like Klipsch uses on the newer Khorns post  c. 2002 (with a Klipsch AK-4 or AK-5 balancing network), stock K-77Fs do just fine crossing over at 4,500 Hz..  The EV T35, which is what the K77 is based on, have been crossed over by EV at 3,500 Hz from the 1950s to about the late 1980s.  The crossovers EV used for this were 12 dB per octave, I think.  I believe the Type A crossovers are only 6 dB per octave.  I have AK-4 crossovers, with a 4,500 crossover point and K77Fs, and there is less midrange harshness with them (or virtually no harshness on many CDs, most SACDs & DVD-As, and, so far, all Blu-rays with dts-HD Master Audio or Dolby True HiFi).

[codewritinfool]

Thank you, Gary!  I learn somethin' new every day!

Mine are from 1968, so I'm not sure if they could have handled it or not with a steeper slope.