cjgeraci Posted June 24, 2006 Share Posted June 24, 2006 You're worried about "loss", yet prefer the sound of a 20 element filter loaded with resistors over one that only uses 5 parts? Autoformers weren't/aren't typically used because they cost 50 times more than using L-pads. No, Altec didn't use them, but I did recently build a pair of autoformer based networks for some Valencias -- maybe Carl will chime in with his opinion regarding the difference between what I built and what he had. At any rate, it is the expensive way to attenuate -- and plain sounds better. I started with AK-4's, have built just about every Klipsch network for the Klipschorn with almost every part imaginable -- and it remains my least favorite network. You need to read, "The Problem with Attenuators", by Paul W. Klipsch. Also, The Dope from Hope with analysis comparing distortion levels between autoformers and L-pads. I have copies at work on my hard drive -- I'll post on Monday if no one else does between now and then. Here's my take on L-pads as opposed to autoformers with respect to Altec horns. Yes, Dean built me a first order, three-way Altec network for my Valencias, with an autoformer as opposed to the second order, two-way original crossover (w/L pads). My upper crossover is now 10,000 - to the Beymas, and therefore, I still utilize the 806A drivers in some of the upper regions. Running the Altec drivers to me with autoformers (vs. L pads) amounted to less distortion through the midrange and helped them handle more power - cleaner. I routinely run the first order Altecs with either a tube amp or a QSC ss amp, and as long as you are careful with the aluminum drivers, a first order (w/auto) can serve you well. In my experience, I have been surprised by the durability of the Altec drivers concerning some of the horror stories. Of course, for routinely louder applications, I am the first to admit using at least second order 'works (I run ALKs for my mains). CJG Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 24, 2006 Share Posted June 24, 2006 Loud ....??? in, maybe 1978 ... i remember hanging 8 Valencias in a disco .. each with thier own DC 300......and a CerwinVega DB-10 a few of you will know what that was .... .............[] Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 24, 2006 Share Posted June 24, 2006 You're worried about "loss", yet prefer the sound of a 20 element filter loaded with resistors over one that only uses 5 parts? Autoformers weren't/aren't typically used because they cost 50 times more than using L-pads. No, Altec didn't use them, but I did recently build a pair of autoformer based networks for some Valencias -- maybe Carl will chime in with his opinion regarding the difference between what I built and what he had. At any rate, it is the expensive way to attenuate -- and plain sounds better. I started with AK-4's, have built just about every Klipsch network for the Klipschorn with almost every part imaginable -- and it remains my least favorite network. You need to read, "The Problem with Attenuators", by Paul W. Klipsch. Also, The Dope from Hope with analysis comparing distortion levels between autoformers and L-pads. I have copies at work on my hard drive -- I'll post on Monday if no one else does between now and then. Here's my take on L-pads as opposed to autoformers with respect to Altec horns. Yes, Dean built me a first order, three-way Altec network for my Valencias, with an autoformer as opposed to the second order, two-way original crossover (w/L pads). My upper crossover is now 10,000 - to the Beymas, and therefore, I still utilize the 806A drivers in some of the upper regions. Running the Altec drivers to me with autoformers (vs. L pads) amounted to less distortion through the midrange and helped them handle more power - cleaner. I routinely run the first order Altecs with either a tube amp or a QSC ss amp, and as long as you are careful with the aluminum drivers, a first order (w/auto) can serve you well. In my experience, I have been surprised by the durability of the Altec drivers concerning some of the horror stories. Of course, for routinely louder applications, I am the first to admit using at least second order 'works (I run ALKs for my mains). CJG Tweeter attenuators have a transformer in them, but unlike an autoformer with taps that have to be manually picked off, the Tweeter attenuators have a multi-step selector, each position represents a different combination of tap settings combinations of the windings. These have an impressive bandwidth response 10hz - 40khz +- .5 db. There are also Tweeter attenuators that use a bunch of resistors, same approach, multiple position selector, results in different combinations of loading. L-pads use 2 widings usally 25 ohms each. As you move the rotary selectory in an l-pad, the values inversly change on both windings. I would not advocate the use of l-pads or resistor based Tweeter attenuators. Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted June 24, 2006 Share Posted June 24, 2006 Charles: On the finer control of attenuation: A variable L-pad, selected to match the impedance of the driver, will work well for this application. I have great respect for Mr. Klipsch, and I understand his preference for a multitapped coil, but many speaker companies use resistive L-pads in their networks. I'm sorry, but I have used both over lots of years, and recently installed a switch on my autoformers. The difference in sound is not detectable to me -- at least as far as my acoustic memory goes, which I admit isn't far. It's a common practice, though. If you need finer adjustment ability, the autoformer as setup is not going to give that to you. The jumps in attenuation are rather course IMO, compared to what is available with a variable control that still maintains a constant impedance. I have two I"m not using you could experiment with, but I don't know the impedance of the driver you're using. If you didn't like it as well as the autoformer in terms of sound quality, it's something that, like anything else, does not have to be permanent. Erik Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted June 24, 2006 Share Posted June 24, 2006 ...and the last thing you need here is ping-pong match concerning the pros and cons of autoformers and variable controls. I don't mean to make things more complex for you. Great job on this project, Charles. Erik Quote Link to comment Share on other sites More sharing options...
chops Posted June 25, 2006 Author Share Posted June 25, 2006 Charles: On the finer control of attenuation: A variable L-pad, selected to match the impedance of the driver, will work well for this application. I have great respect for Mr. Klipsch, and I understand his preference for a multitapped coil, but many speaker companies use resistive L-pads in their networks. I'm sorry, but I have used both over lots of years, and recently installed a switch on my autoformers. The difference in sound is not detectable to me -- at least as far as my acoustic memory goes, which I admit isn't far. It's a common practice, though. If you need finer adjustment ability, the autoformer as setup is not going to give that to you. The jumps in attenuation are rather course IMO, compared to what is available with a variable control that still maintains a constant impedance. I have two I"m not using you could experiment with, but I don't know the impedance of the driver you're using. If you didn't like it as well as the autoformer in terms of sound quality, it's something that, like anything else, does not have to be permanent. Erik Hello Erik, Well since I've had a couple days now to listen to the 902s at the new 600Hz crossover point, with a bunch of different music, I don't think I have to attenuate the 902s any more than they already are. They actually blend in quite well with the K33s. However, I still have the need to boost the treble +3dB, but I can live with that for now. Thanks for the offer on the L-pads, but I seriously don't think I'll be needing them. ---------------------------------------------- I have been told by several members on the Altec User Board that removing the loading caps not only improves the midrange, but also the top end, giving them a little more "air", even moreso than removing the bug screens. I have no plans on removing the screens. With 5 cats raoming around the house all the time, I certainly don't want any kittie fuzz getting in there. LOL Also, am I correct in thinking that by building new networks with Kimber, Theta, Mundorf, etc caps and the new 3636 or 3619 autoformers, I might get a little extra sparkle on the top end as well? Charles Quote Link to comment Share on other sites More sharing options...
BEC Posted June 25, 2006 Share Posted June 25, 2006 Chops said: "Also, am I correct in thinking that by building new networks with Kimber, Theta, Mundorf, etc caps and the new 3636 or 3619 autoformers, I might get a little extra sparkle on the top end as well? Charles" No. To get more sparkle than you get through the GEs would require a change in either the laws of physics or belief in magic. Bob Quote Link to comment Share on other sites More sharing options...
Deang Posted June 25, 2006 Share Posted June 25, 2006 Changing caps will alter the sonic signature -- but they won't put anything on top that wasn't there to begin with. Tweeters work pretty good for that -- have you ever tried one before? Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted June 25, 2006 Share Posted June 25, 2006 Chops said: "Also, am I correct in thinking that by building new networks with Kimber, Theta, Mundorf, etc caps and the new 3636 or 3619 autoformers, I might get a little extra sparkle on the top end as well? Charles" No. To get more sparkle than you get through the GEs would require a change in either the laws of physics or belief in magic. Bob ........."either the laws of physics or belief in magic"........ Oh boy. Here we go again!!!!![][][] Charles, If you decide to remove the loading caps......disregard any statements of the 902 being near bullet-proof crossed at 400 or 500hz low order! tc Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 25, 2006 Share Posted June 25, 2006 chops, I am sending you a PM. Quote Link to comment Share on other sites More sharing options...
chops Posted June 25, 2006 Author Share Posted June 25, 2006 Bob, I didn't mean anything about different caps "adding" to the sound, but rather better audio grade caps possibly passing a little more of the treble information from the original signal. I'm not doubting anyone here (you can be certain of that), and I'm not bashing components or designs, but motor run caps weren't design for audio use, and I'm pretty sure my Altec 902-8B drivers are not 3-phase motors. Is it possible to measure the frequency response of a capacitor to see if it might have a slight rolloff on the extreme top end? Dean, I do not want to go with a seperate tweeter again. I really like the results I'm getting with this 2-way setup, and want to see if I can improve on it, if only a couple of extra dB on the extreme top end. The top end is there, I can hear it right now, it just needs to be pulled out front a tad bit to blend nicely with the great midrange. In fact, giving the +3dB boost via the tone controls at 10kHz almost gets me there, but I'm sure it would sound much better if I were able to get that boost at say 15kHz instead of at 10kHz. And I have to say, since moving over to a 2-way with these Altec drivers and horns, I have NEVER heard speakers this large (Cornwall/Altec combo) image and soundstage so good like these are doing right now. I was not getting anything close to this with the 3-way setup. And if I can get the treble to come out and play nicely with the rest of the music, the imaging and soundstage can only open up that much more. Quote Link to comment Share on other sites More sharing options...
chops Posted June 25, 2006 Author Share Posted June 25, 2006 Charles, If you decide to remove the loading caps......disregard any statements of the 902 being near bullet-proof crossed at 400 or 500hz low order! tc Terry, Trust me, IF I do decide to remove the loading caps, I'll take great caution with the drivers. However, I think I have made up my mind on going with a 3rd order low and high pass filter. It's now just a matter of finding a way of coming up with the proper component values that I need for a 600Hz crossover point. This is where I'm running into a brick wall at the moment. BTW, I finally got around to answering your emails this morning. [] Charles Quote Link to comment Share on other sites More sharing options...
chops Posted June 25, 2006 Author Share Posted June 25, 2006 chops, I am sending you a PM. Got it! Gonna go read it now. [] Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 25, 2006 Share Posted June 25, 2006 remove the loading caps......disregard any statements of the 902 being near bullet-proof crossed at 400 or 500hz low order! tc Yowser ...[] Don't Do It.....!!!! Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 25, 2006 Share Posted June 25, 2006 "but I'm sure it would sound much better if I were able to get that boost at say 15kHz instead of at 10kHz." You could likely do it in the crossover. Something like a capacitor bypassing the autoformer would pass more HF to the driver. Would likely take some trial and error to get it the way you want it to. As far as the loading caps go I pulled them on my 902s. But that was crossing them at 600hz with Al's Extreme Slope networks. Shawn Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 25, 2006 Share Posted June 25, 2006 let me know how the Altec MR 11594 horns sound, shawn .......[:@] Quote Link to comment Share on other sites More sharing options...
chops Posted June 25, 2006 Author Share Posted June 25, 2006 Dean, Al, jc, Bob, whoever, What do you think about this? I'm sure the values are way off, but it's the best I can do with those online calcs. I entered the K33 as 3.4 ohms (CT1526 specs) and 902 as 6.4 ohms (averaged between 6.1 and 6.7 ohms of both drivers). Also, this design would completely eliminate the autoformer and still attenuate the 902 the desired -9dB. And yes, I know I changed my mind again from a 3rd order to now a 6th order. If someone could possibly work out the corrected values, that would be excellent! [] Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 25, 2006 Share Posted June 25, 2006 "And yes, I know I changed my mind again from a 3rd order to now a 6th order. I" The higher you go in order the less likely you are to get a good blend between drivers without multiple attempts at crossover design. With something like a first order get in the ballpark and the driver overlap will cover up problems for example. The sharper you make the crossover the more problems will stand out. 600hz in right in the vocal range so you want a good blend here. Also, keep in mind Altec used the 902 crossed second order at 500hz in movie theaters running 12 hours a day every day. There are other advantages to higher slope crossovers but if you are just doing it for power handling in a home you are wasting your time/money. If you really want to play around with crossover points/orders consider bi-amping with an active crossover. Lots more freedom to try different combos and $$$ wise it probably wouldn't cost much more then building a couple of sixth order passives with audiophile parts. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 25, 2006 Share Posted June 25, 2006 Duke, Sorry, I had them on AuctionSniper... didn't know you wanted them. Still bitter I missed bidding on them the first time he listed them... I forgot to. They closed without any bids at $249 with the 902s. Shawn Quote Link to comment Share on other sites More sharing options...
chops Posted June 25, 2006 Author Share Posted June 25, 2006 "And yes, I know I changed my mind again from a 3rd order to now a 6th order. I" The higher you go in order the less likely you are to get a good blend between drivers without multiple attempts at crossover design. With something like a first order get in the ballpark and the driver overlap will cover up problems for example. The sharper you make the crossover the more problems will stand out. 600hz in right in the vocal range so you want a good blend here. Also, keep in mind Altec used the 902 crossed second order at 500hz in movie theaters running 12 hours a day every day. There are other advantages to higher slope crossovers but if you are just doing it for power handling in a home you are wasting your time/money. If you really want to play around with crossover points/orders consider bi-amping with an active crossover. Lots more freedom to try different combos and $$$ wise it probably wouldn't cost much more then building a couple of sixth order passives with audiophile parts. Shawn So just go with a simple 1st or 2nd order? What about using the two reisitors instead of the autoformer? Any advantages there other than saving a little money? Quote Link to comment Share on other sites More sharing options...
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