Schu Posted February 12, 2019 Share Posted February 12, 2019 I remember some discussion a while ago about 9k HZ and La Scala/Klipschorn... at the time I didn't pay that much attention to it. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 12, 2019 Share Posted February 12, 2019 K55 return response if no bandpass. But, the question is did it ever matter? Quote Link to comment Share on other sites More sharing options...
Schu Posted February 12, 2019 Author Share Posted February 12, 2019 To me, it's only discernable graphically... I don't think I can hear it. Quote Link to comment Share on other sites More sharing options...
Deang Posted February 12, 2019 Share Posted February 12, 2019 So, that tone is being generated through a tablet, right? Some of the older spring loaded K-55s had "the problem", not all of them. More of a K-77 problem than a squawker problem, imho. Quote Link to comment Share on other sites More sharing options...
JohnA Posted February 12, 2019 Share Posted February 12, 2019 Schu, which xover are you running? Which squawkers? The 9 kHz bounce is shown in this graph. Both K-55s have it at about -8 dB. There are a couple of solutions, depending. 2 Quote Link to comment Share on other sites More sharing options...
garyrc Posted February 12, 2019 Share Posted February 12, 2019 K55X: Didn't they eliminate that 9K bounce back when they started crossing over at 4.5K? I don't know about the La Scala, but in the Khorn, in about 2002, or so, they started rolling off the K55X at about 4.5K, at 12 dB per octave, so at 9K the response through the K55X would be about 12 dB lower than it is in the c1982 graph @JohnA posted, wouldn't it ? I believe, previously, there was no K55 roll off at all. K77F: In my room, at about 13 feet away, the K77F doesn't seem to have a peak at 9K. 5 dB vertical divisions 1 Quote Link to comment Share on other sites More sharing options...
Schu Posted February 12, 2019 Author Share Posted February 12, 2019 That is isnteresting... indeed it's a 55x. It's fairly universal no matter what I am listening to... although some individual songs that region goes fairly flat... but it's rare. I am pretty sure it's NOT a room mode and unrelated to amplification because both of those variables can be changed at will with little affect. I am not really sure it's even audible because the region is very narrow and definetely contained between 9-10k. It's the La Scala AK4 XO I think. (Maybe it's the AL4?) Quote Link to comment Share on other sites More sharing options...
Schu Posted February 12, 2019 Author Share Posted February 12, 2019 3 hours ago, Deang said: So, that tone is being generated through a tablet, right? Some of the older spring loaded K-55s had "the problem", not all of them. More of a K-77 problem than a squawker problem, imho. the tone/tune is being generated independent of the tablet D... freestanding handheld. Quote Link to comment Share on other sites More sharing options...
Panelhead Posted February 13, 2019 Share Posted February 13, 2019 Do both your LS ii has this Hi-Q resonance? The difference in the crossovers may address this? Shorting across that one resistor may be a “fix” for it. Quote Link to comment Share on other sites More sharing options...
Schu Posted February 13, 2019 Author Share Posted February 13, 2019 It's a characteristic of the LSii... and perhaps the later Klipschorns. Quote Link to comment Share on other sites More sharing options...
Panelhead Posted February 13, 2019 Share Posted February 13, 2019 Looks like you have sold your original LS ii. Guess that eliminates the small change in the crossover. My first thought is it is a resonance in the midrange horn. But that is also the second harmonic of the crossover point between the K-55 and K-77. High order crossovers can ring. If I understand the graphical display, there is a peak at 13.5 KHz. Which is the 3rd harmonic. That makes me think it is the high pass to the tweeter causing this. Quote Link to comment Share on other sites More sharing options...
Schu Posted February 13, 2019 Author Share Posted February 13, 2019 Oh sorry... yes, the original LSiis are long gone. The scale of the waterfall, its not completely symmetrical from left to right. The scale from 10k to 20k is compressed (that's why there is such a step roll off) so that peak you see might be around 14-16k. To me, purely a guess, it looks like a roll off crossover issue, but I guess it could definetely be a resonance issue also. Quote Link to comment Share on other sites More sharing options...
Schu Posted February 13, 2019 Author Share Posted February 13, 2019 I wonder if the waterfall would be less dramatic with additional smoothing applied which would "average" that area. Quote Link to comment Share on other sites More sharing options...
Panelhead Posted February 13, 2019 Share Posted February 13, 2019 The high pass filter could be a “trap”. The capacitor and choke resonate and dump energy between them. The “quality” of the components plays a role here. ALK, Deano, BEC, and others are more qualified to offer suggestions. I usually damp capacitors electrically. But in this case a swamping resistor across the final choke might be the most effective. Something like a 2 - 3K thick film, non-inductive in parallel with choke would identify if this is the issue. For the output coupling cap, a 0.536 ohm resistor in series with 0.1 ufd cap would be a start as a damper in parallel with the stock large value film cap. If I had a test rig I could check mine to see if they show the same peaks. I need an analyzer. It would be easy to drop back panel and jumper in components to see if damping the choke, caps, or both effect the amplitudes and width of the anomalies. BTW, I do not hear any misbehavior in my LS ii either. Quote Link to comment Share on other sites More sharing options...
JohnA Posted February 13, 2019 Share Posted February 13, 2019 10 hours ago, garyrc said: K55X: Didn't they eliminate that 9K bounce back when they started crossing over at 4.5K? I don't know about the La Scala, but in the Khorn, in about 2002, or so, they started rolling off the K55X at about 4.5K, at 12 dB per octave, so at 9K the response through the K55X would be about 12 dB lower than it is in the c1982 graph @JohnA posted, wouldn't it ? I believe, previously, there was no K55 roll off at all. K77F: In my room, at about 13 feet away, the K77F doesn't seem to have a peak at 9K. 5 dB vertical divisions The Atlas PD5-VH also shows the 9k bounce in its plane wave tube response. Putting it on a horn like a K-400 that has some HF gain would exaggerate it. So, I'm sure the K-55-X also has it. Depending on the design, the AK4 xover would knock it down quite a bit. If it is a 2nd order slope, the bounce should be down at least 20 dB. Nothing I have on K-77s shows a peak anywhere near 9k. I'm sure the K-77-? Is not part of the problem. Schu, I would not place any faith in results obtained by a tablet or when using music as a source. Your AL4 xovers should tame the squawkers bounce well. 1 Quote Link to comment Share on other sites More sharing options...
Schu Posted February 13, 2019 Author Share Posted February 13, 2019 I understand its dynamic data as opposed to fixed... and therefore less ideal. However, it appears across the board of most all recordings... so I have been watching it for sometime now and thinking about it. I tried moving room items around, no affect. I tried multiple amp configurations, no affect. I am fairly certain it's NOT an instrument item because I can generate sound that clearly fills that 9k region... and like I had said, there are a handful of songs that also fill that region. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.