Q-Man Posted November 15, 2003 Share Posted November 15, 2003 I'll try to take a better picture later today. I don't think the curve of this cabinet looks too bad. I need to live with it for a while to decide if I should cover the horn with grill cloth or not. Right now the horn is painted with the same black lacquer that i used on the cabinet. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 15, 2003 Share Posted November 15, 2003 Q-man, That's impressive! What the heck is that wire down the front though? It's messing up the asthetics something awful! Without the wire, it a serious looking speaker! I assume you are crossing over at 300 Hz. I think that should be a very good place considering that's where the Khonr woofer has it's peak. The efficiency should really be up assuming the high driver level is set properly. Al K. Quote Link to comment Share on other sites More sharing options...
Q-Man Posted November 15, 2003 Author Share Posted November 15, 2003 Al, I put the Klipschorns on wheels and the wire is so I can pull them around with me. Seriously that is the tweeter wire, I mounted the tweeter below the horn. This puts the tweeter at ear level when sitting down. Right now the crossover is at about 450Hz with a 16uF mid. cap. John Warren is working on a new network design just for this mod. He took over when he saw me having trouble getting to 400Hz. He found the impedance of the driver at 400Hz to be around 22 Ohms. The 290 is said to have a Fs of 225Hz, JW finds it closer to 260Hz. I would like to crossover at 350Hz, but John thinks that may be too close to the Fs of the driver. He says that idealy one should be at least one octave above Fs(in this case about 500Hz)to keep distortion low. This is one reason you find distortion with the K55. So we agreed to go for a 400Hz high pass filter. As you found with your modified Belle, this top end is so much better sounding then the Klipschorn. I know Paul knew this. I think he wanted to keep the speaker as cheap as possible to put it into more peoples homes. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 15, 2003 Share Posted November 15, 2003 Q-man, I can't see where the tweeter could be in the Picture unless the front of the Khorn is all grill cloth or something! You do need a better picture. That wire sticking out there is a real shame!!! YUCH! That driver resonance problem is another reason for an extreme slope crossover. I could crossover at 350 Hz or even lower and nail 280 by 30 dB easily! Al K. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 15, 2003 Share Posted November 15, 2003 Q-man, I just scaled the 600 Hz network I posted a day or so ago to drop 280 Hz in the 'notch". The crossover falls a 325 Hz and kills 280 Hz by 25 dB or more. It would be the size of Texas though! The computer plot of the highpass section is attached. Al K. OOPS.. I just reread you post. I saw 260 Hz and read 280 Hz! That would put the crossover down lower, closer to 300 Hz. Quote Link to comment Share on other sites More sharing options...
Q-Man Posted November 15, 2003 Author Share Posted November 15, 2003 Al the tweeter isn't attached in that picture. That one was taken durning assembly a few weeks ago. I'll take another picture. JW was thinking about a third order crossover instead of the first order AA. Let me reread your reply and digest it and get back to you. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 15, 2003 Share Posted November 15, 2003 Q-man, I just ran the numbers on that... A 3rd order (Butterworth response of 18 dB / octave) will get you 20 dB at 260 Hz with a crossover around 470 Hz. If you allow some passband ripple, about 0.2 dB I think is a good idea, you can get 24 dB with the same crossover frequency. The crying shame about that is you could have used an Altec 511 horn instad of that big 311! You are not taking full advantage of it. I just remembered seeing the pictures you posted of the early stages of the 311 mounting arangement and saw the tweeter below the 311 mouth. Am I seeing grill cloth where I thought I was looking at the front of the Khorn itself? Is the wire going through grill cloth? AL K. ................... Quote Link to comment Share on other sites More sharing options...
Q-Man Posted November 15, 2003 Author Share Posted November 15, 2003 Al, No grill cloth, that was another pair that I was using while experimenting. I hope we can see the tweeter in this shot. I can't take a picture of a black speaker. The tweeter is still only temporary, I want to build a curved box to match the horn above. I'm not ready to post pictures of these yet. I only did so because we started talking about them in the other post. Quote Link to comment Share on other sites More sharing options...
Q-Man Posted November 15, 2003 Author Share Posted November 15, 2003 This is the pair that had the bottom covered with black grill cloth. The guy I bought them from painted them black. I just finished stripping them. I'm getting them ready to sell. I need to oil them now. They were originally Walnut Oiled. I used them in my theater room when they were black, but since I'm going to sell them I want them to be original. See I can take a picture of a non black speaker. Remember they are dull, no oil yet. The shine on top is smoked glass. Thanks for running the numbers. I'll get back with you later. I have to take my kids to a car show now. Cars from the 60's Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 15, 2003 Share Posted November 15, 2003 Q-man, I think I see. The tweeter is simply not in the first picture at all, just the wire that would go to it if it was. Right? I like the place you have mounted it. The temptation would be to stick it in center of the mouth of the big horn. I never liked that idea at all! Al K. Quote Link to comment Share on other sites More sharing options...
Rockets Posted November 15, 2003 Share Posted November 15, 2003 Nice job! I wish I had some wood working skills...I'm limited to measuring with a micrometer, marking with chalk and cutting with an axe...... Quote Link to comment Share on other sites More sharing options...
Q-Man Posted November 15, 2003 Author Share Posted November 15, 2003 AL, Your extreme slope crossover compared to the 3rd order Butterworth is very interesting. I may be asking you some more questions about it. I certainly want to take full advantage of this 300Hz horn. I may even do so by living with some distortion to crossover where I want to. Always compromises. Right now with a 450Hz first order crossover it sounds much better then the stock Klipschorn so I have hope. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 16, 2003 Share Posted November 16, 2003 Q-man, If you decide to try the extreme-slope idea, I will design it for you, but I may not have time to build it for quite a while. I will also need to have somebody (maybe John Warren) do some impedance measurements on the Khorn woofer at 300 Hz. John might be willing to built it too. I warn you though, it will be BIG! The problem with running a conventional crossover with the cross frequency to close to the resonance of the driver is not only distortion but the possibility of damage to the driver. There is nothing to control the diaphragm motion at resonance. That's why John moved the crossover up. Al K. Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted November 16, 2003 Share Posted November 16, 2003 Qman, this looks pretty cool. Did you have a pic in your original post on the thread...? I've been unable to find it. If you wouldn't mind to post that again, sure would appreciate that. I'm following with interest as I'm about to pick up a pair of rough Khorn cabs (type c) to refurb. Still don't know whether I'll go for stock horns with ALK networks or work along the lines you and Al are doing. I know Al says it sounds better. Your take also? Dee Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 16, 2003 Share Posted November 16, 2003 ---------------- On 11/16/2003 7:23:32 AM Al Klappenberger wrote: I warn you though, it will be BIG! ---------------- Oh goodness! I'm already hurting from lugging around the 290! Based on the 311/290 combination three "boundary" conditions for selecting the topology are considered. The horn has a useful LF extension limit to 300Hz. The driver (290-16L) has a phase-plug bandwidth between 500-7kHz and an Fs of (this one anyway) of 260Hz. Other factors are an indestructable phenolic diaphragm, 120W RMS dissapation above 500Hz, 100W above 300Hz and a sensitivity within the phase-plug bandwidth of about 107dB/W/m (outside of the phase-plug bandwith sensitivity drops fast). Since this isn't a PA apllication which, BTW, "is" the intended application for this horn, keeping distortion to a minimum is important. Excursion goes roughly as the inverse sq of the frequency and distortion trends with excursion so staying away from 260Hz makes sense but we still have 100W of dissipation margin at 300Hz but we are taking a debit in sensitivity. I considered a 3rd order at 400Hz which would mean that at 200Hz, the driver would see about 1/16 of the power it would at 400Hz. Not perfect, but given that the driver is (essentially) indestructable and PWK has been getting away (?) with a 1st order on a considerably less capable transducer, the 3rd order for this driver seemed unecessary. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 16, 2003 Share Posted November 16, 2003 John, Everything you say is true. I just think it's a shame to have all that horn there and not be able to use it down to it's lower limit. With a sharper highpass filter, you could run it to full power (if you ears could stand it) down to, or even below, its lower limit and still be sure low frequencys seeping through the filter will not casue the diaphragm to hit the phase plug. The extreme-slope network will do that and reduce driver interference between the Khorn woofer and the highs too! If you get a hernia from lugging the crossover around, well, that's the price you pay! Nothing good comes without a price! Al K. Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 16, 2003 Share Posted November 16, 2003 ---------------- On 11/16/2003 9:42:18 AM Al Klappenberger wrote: John, Everything you say is true. I just think it's a shame to have all that horn there and not be able to use it down to it's lower limit. With a sharper highpass filter, you could run it to full power (if you ears could stand it) down to, or even below, its lower limit and still be sure low frequencys seeping through the filter will not casue the diaphragm to hit the phase plug. The extreme-slope network will do that and reduce driver interference between the Khorn woofer and the highs too! If you get a hernia from lugging the crossover around, well, that's the price you pay! Nothing good comes without a price! Al K. ---------------- I agree and the vertical slope designs have merit. But compression distortion in the throat goes up like a rocket within the first octave above Fs. The air between the phase-plug and the diaphragm behaves more like a fluid (it is becoming incompressible) than a gas and causes the diaphragm to "jelly-fish". Phenolics have no problem with it, they just buckle and unbuckle. I open minded though! Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 16, 2003 Share Posted November 16, 2003 John, All good engineering is a tradeoff. Just figure, what would you rather have making the sound at 400 Hz, the big squawker horn, the Khorn woofer, or BOTH in the case of the usual 3rd order crossover. The trade off is, of course, the hernia you get hauling around the big crossover! Al K. Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 16, 2003 Share Posted November 16, 2003 ---------------- On 11/16/2003 10:22:44 AM Al Klappenberger wrote: John, All good engineering is a tradeoff. Just figure, what would you rather have making the sound at 400 Hz, the big squawker horn, the Khorn woofer, or BOTH in the case of the usual 3rd order crossover. The trade off is, of course, the hernia you get hauling around the big crossover! Al K. ---------------- Dual 2123Js The constraints are gone, the Klipschorn can be cutout at 200Hz and a pair of these, with the right crossover and each in a Qts alignments of .5 are fantastic. Most of the commercial horns manufactured today will not go where we wan them to go in this application. When the tradeoff become to large, an alternate technology is sought. High efficiency, arrayed mids. jw Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 16, 2003 Share Posted November 16, 2003 John, Going to a direct radiator for the midrange is one way to do it, but combining a direct radiator and a horn is another set of tradeoffs! It boils down to picking which poison you prefer to kill yourself with! Al K. 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.