Cornwalled Posted February 27, 2009 Share Posted February 27, 2009 Hello, I am finding that my Cornwalls have a midrange resonance / coloration that is really starting to get to me. It's one of those things that once I've heard it, I can't really get away from it. I find I frequently turn down the volume because it sounds fatiguing. It seems to be the most prevalent in the octave above middle c on a piano. This frequently falls in the range of electric guitar, upper vocals, etc. They just seem to have a real resonance in that area. They are all original 1981s if that helps. I have heard of people dampening the midrange horn, and am thinking that could be an option. Another unrelated frustration I am having is a boomy / bloated bass. My room is approximately 15 x 15 x 10 (give or take a foot), so I know that's small for these speakers, perhaps that could be contributing to both problems- i.e. I'm sitting to close to them for smooth midrange, and the room is too small for proper bass. To be honest, part of me is strongly considering selling them, because I just can't get over the "PA Speaker" kind of sound I sometimes get with them. They just don't seem accurate, very colored. I'm really trying to get an accurate, non fatiguing sound that I can listen to for hours on end, and I find right now that my ears get tired with these. I'm driving them with a VTL ST-85 tube amp, but have a SS Marantz receiver as a preamp. Perhaps a tube preamp could smooth things out a bit? I love what they do for movies- very exciting and lively, but I find for music, they can wear me out. Don't get me wrong, I do like the speakers overall, and they certainly represent an excellent value on the used market. Mine are pretty beat cosmetically, so I'd probably only get $350-400 for them if I sold them. So, I couldn't imagine any $400 speaker that could do what these guys do in terms of full range sound and impact. I just sometimes feel they're just not quite as refined as my sensitive ears would like. Any thoughts or suggestions would be appreciated. Thanks, Jon Quote Link to comment Share on other sites More sharing options...
Budman Posted February 27, 2009 Share Posted February 27, 2009 i would send the crossovers to bob crites ( BEC ) here on the forum. Quote Link to comment Share on other sites More sharing options...
Seadog Posted February 28, 2009 Share Posted February 28, 2009 Dampen the mid horns and add P-traps to the networks when you re-cap them. Quote Link to comment Share on other sites More sharing options...
kdcarroll Posted February 28, 2009 Share Posted February 28, 2009 Seadog - What does the P-trap do specifically in the crossover to dampen resonance? Thanks!! K Quote Link to comment Share on other sites More sharing options...
Seadog Posted February 28, 2009 Share Posted February 28, 2009 The P-trap is a frequency trap that eliminates 9kHz going to the K-55-V driver. This driver is supposed to fall off naturally at around 6kHz, however, for some reason it flares up again at 9kHz and can create a harshness. It is simply a 0.10 mH inductor in parallel with a 3.0uF capacitor on the squawker's positive lead. Search the forum for "P-trap", there are several good threads on the subject. To my ears, the P-trap also seems to clean up the sound from the tweeter, adding more high end detail (because the squawker is now dead above 6kHz). Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted February 28, 2009 Share Posted February 28, 2009 nicely done and explained Mr. Dog. Quote Link to comment Share on other sites More sharing options...
Speedball Posted February 28, 2009 Share Posted February 28, 2009 My experience of going to a tube preamp from a receiver was quite amazing. Not only "smooth" but to hear what was never there before is what surprised me the most. Also being able to listen to a looong time without fatigue which I know exactly what you mean about wearing you down. Of course the reworked Dean crossovers was a mighty big step in the right direction for me too. I envy your amp...[] When I dampened the horns on my 4.2's w/ HVAC monkey grip it made such a difference I wound up removing most of if not all of the material, it made quite a difference. These audio engineers really are on to something, being able to design and change the sound of a speaker. Quote Link to comment Share on other sites More sharing options...
Deang Posted February 28, 2009 Share Posted February 28, 2009 I am finding that my Cornwalls have a midrange resonance / coloration...I find I frequently turn down the volume because it sounds fatiguing...Another unrelated frustration I am having is a boomy / bloated bass." Crossover work will help, but it won't change the overall character of the speaker. As for the P-trap, I've built plenty of those into filters with good results -- but along with knocking down that spike, it also adds almost 2dB of attenuation to the driver -- so it's difficult to say which of the two is providing the subjective improvement. I believe the real culprit is the mid-horn, since because of its narrow throat is prone to air overload at even modest volume levels. As you guessed, the issue with your bass is room/placement related. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted February 28, 2009 Share Posted February 28, 2009 I believe the P-Trap is meant for the earlier K55Vs. There was a change in the phase plug in the later models. You can tell the difference by noting whether the wires are soldered (newer model) or not (older model). I believe that newer caps will simply deliver more energy to the tweeter. This may or may not be your problem (and take Dean's or BECs advice not mine anyway about the crossover). If you could be more specific about the mid-range problems it would be helpful (eg, what instruments is it most exaggerated etc). Otherwise the rest of us are only speculating. You are correct, the bass problems are probably room related (unless you are severely abusing an undersized amplifier). Although, it will not entirely correct the problem(s), sometimes moving the speakers around can change things for the better (do this systematically and it will be a tedious procedure - but it is worthwhile). Good Luck Quote Link to comment Share on other sites More sharing options...
Deang Posted February 28, 2009 Share Posted February 28, 2009 I believe the P-Trap is meant for the earlier K55Vs. There was a change in the phase plug in the later models. You can tell the difference by noting whether the wires are soldered (newer model) or not (older model). That's true. I believe that newer caps will simply deliver more energy to the tweeter. This may or may not be your problem (and take Dean's or BECs advice not mine anyway about the crossover). Also true, but depending on how old the capacitors are, a changeout might also deliver more energy to the mids as well. Quote Link to comment Share on other sites More sharing options...
djk Posted February 28, 2009 Share Posted February 28, 2009 "It seems to be the most prevalent in the octave above middle c on a piano" That falls in the range of the crossover point of the midrange. I would suggest adding a 15R/12W (or higher W) resistor in parallel with the mid driver, and change the capacitor from 4µF to 8µF All horns with small mouths have impedance peaks near their cut-off points. These cause peaks in the response as well. Swamping these peaks with a resistor will tame a lot of these response peaks. The value change on the capacitor keeps the crossover frequency the same. Quote Link to comment Share on other sites More sharing options...
Budman Posted February 28, 2009 Share Posted February 28, 2009 don't forget to retighten all the screws in all of the drivers in the motor board. Quote Link to comment Share on other sites More sharing options...
Cornwalled Posted February 28, 2009 Author Share Posted February 28, 2009 Hello everyone, Thanks for the suggestions. Now to answer your questions to the best of my ability. My K-55Vs are the older type - i.e. not press on connections. The cable is soldered direct to the driver. The crossovers are also original from 1981, so 28 years old. Wow, hard to believe they're that old! I actually bought caps over a year ago, but have been reluctant to recap them because I've been afraid it would make them even brighter than they are. As far as quantifiying what type of instruments aggravate it- electric guitar would be the worst I think. If anyone is familiar with Roger Waters solo music, track 11 on his "The Pros and Cons of Hitch Hiking" is a good example. Eric Clapton plays electric guitar on that album, and towards the end of the track, during the big chorus he plays some solo notes behind Roger's vocal. These fall right in the range of irritation. Also, Roger's voice sometimes disturbs a brutal resonance- this one being the 'E' above middle C. A classical example is on a rather unknown album called "Silencio". A particular favorite is "Come In" by Vladimir Martynov. This song is mostly strings (no brass or winds), but occasionally a wood block and vibraphone will play, and the knock of the woodblock is painful. It seems to nail the resonance perfectly..lol. Also, certain notes in the vibraphone really stick out, instead of sounding balanced. I have played it on other speakers and everything sounds smooth, natural and even. So, what I'm really looking for is reduced coloration. To be honest, I really have my doubts as to how much the crossover will help. I dunno, I guess if you really get in there and re-design a crossover to have a dip at the specific resonant freq. it could help, but that would seem pretty complicated. It would seem better to prevent the resonance from occuring mechanically in the first place. That's just my thoughts anyway... I've actually started to give thought to not going horn anymore, as crazy as that may sound to some of you, the horn faithful! Just because I'm afraid I'll always hear that resonance / coloration that becomes increasingly common / irritating with horns. Even the uber-expensive Avant Gardes still have horn coloration, according to Stereophile anyway. I've only heard that unos, in a terrible environment (trade show) so I can't comment personally. As always, your thoughts are greatly valued. Thanks! Jon Quote Link to comment Share on other sites More sharing options...
Deang Posted February 28, 2009 Share Posted February 28, 2009 You have the caps, I suggest you use them -- they'll sound a lot better. Quote Link to comment Share on other sites More sharing options...
greg928gts Posted February 28, 2009 Share Posted February 28, 2009 You've received some very good advice here. FWIW, I too have heard the same exact things you are describing with your Cornwalls. Cornwall bass doesn't sound good in my living room, or maybe I should say my living room would need some treatment to work well with Cornwalls. Anyway, I know exactly what you're talking about. I'm a Khorn guy, so my Cornwalls only come out once in a while, but I've often wondered if I could get crossovers like the ALK Universals for my Cornwalls. I love what the Universals do for my Khorns and La Scalas. Besides being able to easily attenuate the midrange, they just sound so much smoother. I wonder if djk's suggestions are along the same lines as what Universal networks would do for the Cornwall? I was talking to Gothover the other day about making a wooden tractrix horn for the Cornwall. We both thought that would be a great idea. I encouraged him to do it first! I think the Cornwall crosses at 600Hz, which would mean a 400Hz Fc horn, which I think would fit in a stock Cornwall just fine. If my experience upgrading my Khorns is any indication, upgrading your crossovers and changing to a wooden tractrix midrange horn with a better quality driver in your Cornwalls would take care of the problems you are experiencing with the midrange. It might even surprise you with how much better it would sound. I've heard people say that woofers get old too, so maybe going with the Bob Crites cast-frame woofers would help. I suspect that what others have said here about room treatments and placement will probably make more of a difference with the bass though. Don't give up on horns just yet. Greg Quote Link to comment Share on other sites More sharing options...
djk Posted March 1, 2009 Share Posted March 1, 2009 "I've actually started to give thought to not going horn anymore" If you're too lazy to use the caps you already bought, and to cheap/lazy to buy a couple of $1 resistors, maybe you should sell them. I doubt the caps will fix the problem, but if you add the resistor I bet the problem will either be eliminated, or greatly reduced. If it is just greatly reduced, you may need new diaphragms. Quote Link to comment Share on other sites More sharing options...
Speedball Posted March 1, 2009 Share Posted March 1, 2009 Yup, sounds crazy to me not wanting to go horns but what ever makes you happy. My Reference series speakers are so smooth and listensble it is amazing, paired with the wrong amp it is everything bad you describe. Good Luck. Quote Link to comment Share on other sites More sharing options...
boom3 Posted March 3, 2009 Share Posted March 3, 2009 As the Romulans said, I have been away, now I am back...[H] The bass problem can be addressed in two ways: One, move 'em out from the corners by about 18 inches, and Two, use a good sub crossed over at 60 Hz. Both these actions have made the Corns much better for me. The mid horn problem is more complex, and I can only second the approaches alreday mentioned here. If you have a plastic horn, adding rope caulk is not going to help. You might try, on a temporary basis, a plastic foam insert just inside the mouth, around the perimeter The foam should be the open-cell kind used for packing and window air conditioner trim. It will have to be trimmed so that it does not interfere with the grille. The key word is temporary , you can use tape to attach it to the horn and baffle. Some have reported good results with this on other horns, some feel it makes no difference. As noted before these horns (K-400 series, 500, 600, 700) are just too small and depend on the baffle to reinforce the region around cutoff. However, they still outperform most direct radiator mids I've ever heard. The plastic foam stunt can't make the horns bigger, but some feel it reduces upper range harshness. Quote Link to comment Share on other sites More sharing options...
Istari Posted March 3, 2009 Share Posted March 3, 2009 John, If you are tired of those ugly, old, black, beat up Cornwalls you can always sell them back to me! I could use them now! Jim Quote Link to comment Share on other sites More sharing options...
Dflip Posted March 3, 2009 Share Posted March 3, 2009 P-trap diagram, I believe it originally came from Dean. This ones for those who can't read circuit diagrams. Quote Link to comment Share on other sites More sharing options...
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