popbumper Posted December 9, 2004 Share Posted December 9, 2004 For those interested, I have compiled a list of autotransformers (typically found in the squawker sections of crossovers) and their corresponding attenuation values. These values were obtained through review of crossover schematics and confimation with Klipsch support. If you are aware of any others not listed here, my apology, but this does cover quite a few platforms. T2A: -12dB (Cornwall "early", Heresy and Quartet) T5A: -6dB (Chorus, KLF30) T7A: -10dB (Forte II and KLF20) T8A (also called 3507): -8dB (Cornwall II) T10A: -9dB (Forte) "3504": -10dB (Heresy II) As some are no doubt aware, Bob Crites can supply the model 3636 replacement transformer, for those interested in DIY. This transformer can easily be configured for any attenuation value between -1dB and -12dB, and is a valuable replacement for any of the stock Klipsch units. Popbumper Quote Link to comment Share on other sites More sharing options...
Deang Posted December 9, 2004 Share Posted December 9, 2004 I thought I had an email from Bob showing the attenuation levels with the corresponding taps for the new autotransformer -- but I can't find it. Bob? Quote Link to comment Share on other sites More sharing options...
BEC Posted December 9, 2004 Share Posted December 9, 2004 Dean, I think I sent you a printed sheet on that with your last box of dope (or whatever) that I sent you. Bob Also, the -12 db is the maximum (tap 1) the T2A is capable of. It can also do: -3 (tap 4), -6 (tap 3), and -9 (tap 2). Bob Quote Link to comment Share on other sites More sharing options...
popbumper Posted December 9, 2004 Author Share Posted December 9, 2004 Dean: For the model 3636: Input taps Output taps Attenuation (dB) 0-X 0-4 1 0-Y 0-4 2 0-5 0-4 3 0-X 0-3 4 0-Y 0-3 5 0-5 0-3 6 0-X 0-2 7 0-Y 0-2 8 0-5 0-2 9 0-X 0-1 10 0-Y 0-1 11 0-5 0-1 12 Popbumper Quote Link to comment Share on other sites More sharing options...
Deang Posted December 9, 2004 Share Posted December 9, 2004 Very sweet. How did you get that into the post without losing your tabs. I've been trying figure that out for months. Quote Link to comment Share on other sites More sharing options...
popbumper Posted December 9, 2004 Author Share Posted December 9, 2004 I got lucky....I fully expected it to be all twisted, and was happily surprised that it formatted properly!! Popbumper Quote Link to comment Share on other sites More sharing options...
BEC Posted December 10, 2004 Share Posted December 10, 2004 How about the T4A. Anyone know the value of attenuation on that one? Bob Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted December 10, 2004 Share Posted December 10, 2004 Bob My understanding from Stephen Phillips was the T4A is -4db. I learned this when changing my AK2 to an AK3 network in my Khorns. mike Quote Link to comment Share on other sites More sharing options...
BEC Posted December 10, 2004 Share Posted December 10, 2004 Mike, I was thinking that it was -4db also. Just couldn't find it in writing anywhere so was looking for confirmation. Thanks Bob Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted December 11, 2004 Share Posted December 11, 2004 Hi, Bob: Please look for a PM/email. Thanks, Erik Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted December 11, 2004 Share Posted December 11, 2004 Guys, I just rememberd that I did this for the 3636. It's computer generated data. The columbs will only line up if you use a fixed pitch font. Cut and past the the table to some text editor. Al K .................. 5 Y X 4 3 2 1 0 5 0.00000 0.10880 0.20567 0.29205 0.50000 0.64519 0.74881 1.00000 Y 0.00000 0.09687 0.18325 0.39120 0.53639 0.64001 0.89120 X 0.00000 0.08638 0.29433 0.43952 0.54314 0.79433 4 0.00000 0.20795 0.35314 0.45676 0.70795 3 0.00000 0.14519 0.24881 0.50000 2 0.00000 0.10362 0.35481 1 0.00000 0.25119 0 0.00000 The actual turns ratios of the 3636 transformer for each tap are listed in the far right column of the computer generated table. The turns ratio (and therefore the voltage ratios) between any two taps with input between 0 and 5 are given in the table. These would be the ratios possible for use with my networks. Attenuation is of course: dB = 20 * log10(ratio) Here's the same table expressed in dB: 5 Y X 4 3 2 1 0 5 -19.27 -13.74 -10.69 -6.02 -3.81 -2.51 0.00 Y -20.28 -14.74 -8.15 -5.41 -3.88 -1.00 X -21.27 -10.62 -7.14 -5.30 -2.00 4 -13.64 -9.04 -6.81 -3.00 3 -16.76 -12.08 -6.02 2 -19.69 -9.00 1 -12.00 0 Setting sorted by attenuation: atten atten between ratio dB taps 0.08638 -21.27 X 4 0.09687 -20.28 Y X 0.10362 -19.69 2 1 0.10880 -19.27 5 Y 0.14519 -16.76 3 2 0.18325 -14.74 Y 4 0.20567 -13.74 5 X 0.20795 -13.64 4 3 0.24881 -12.08 3 1 dB 0.25119 -12.00 1 0 -- 12 0.29205 -10.69 5 4 0.29433 -10.62 X 3 -- 10 0.35314 -9.04 4 2 0.35481 -9.00 2 0 -- 9 0.39120 -8.15 Y 3 -- 8 0.43952 -7.14 X 2 -- 7 0.45676 -6.81 4 1 0.50000 -6.02 3 0 -- 6 0.50000 -6.02 5 3 0.53639 -5.41 Y 2 0.54314 -5.30 X 1 -- 5 0.64001 -3.88 Y 1 -- 4 0.64519 -3.81 5 2 0.70795 -3.00 4 0 0.74881 -2.51 5 1 0.79433 -2.00 X 0 0.89120 -1.00 Y 0 1.00000 0.00 5 0 Quote Link to comment Share on other sites More sharing options...
Deang Posted July 16, 2005 Share Posted July 16, 2005 I have a question: Using the 3636 to build an AK-3 requires using X as the input tap, and 3 as the output tap to the squawker. To know the correct primary capacitor value, don't we also need to know the various impedance values with the different tap combinations? IOWs, I don't think it remains 13uF regardless of where you're dancing! Quote Link to comment Share on other sites More sharing options...
jwc Posted July 16, 2005 Share Posted July 16, 2005 It's about time someone posted this. Very helpful. Ditto question of Dean's....what happens to the impedance values with the change of taps. There very badly needs to be a FAQ for this board. The above should be included. Trey? Amy? Quote Link to comment Share on other sites More sharing options...
BEC Posted July 16, 2005 Share Posted July 16, 2005 Dean, With the 3636 connected correctly for 4 db, the impedance should be the same as a T4A. Bob Quote Link to comment Share on other sites More sharing options...
Deang Posted July 16, 2005 Share Posted July 16, 2005 FAQ, are you kidding me? Even if there was one, it wouldn't include data for non-Klipsch parts or products. How much do you think Klipsch knows or cares about the UT 3619 or 3636? How about the impact of a swamping resistor and/or bandpass circuit on the deliverable acoustic output of the squawker? Half the things discussed on this forum are of no interest to them. Quote Link to comment Share on other sites More sharing options...
jwc Posted July 16, 2005 Share Posted July 16, 2005 Is this a leap of faith...maybe so. However, I think it would be appropriate for "Updates and Modifications". Stating the data from a past product such as a T2A is no different than stating the specs of a K77. Yes, putting non- Klipsch products in a FAQ would never happen. Quote Link to comment Share on other sites More sharing options...
tigerwoodKhorns Posted July 16, 2005 Share Posted July 16, 2005 Guys, how about a FAQ Thread named simply "FAQ" We can start posting topics in tehe two channel that we want to be in the thread, when a final version for each topic is generally agreed upon (thats gonna be tough) it can be posted to the FAQ's. All we need to agree to is general info, not opinions like Al's xover can beat up deans xover and Bob's can beat um both up, just more like here are all of the x overs for the each speaker and the creators coments regarding the same for the non-Klipsch ones. Two problems I see are: Getting any sort of agreement as to what to post. Some numbscull posting junk on our newly created jewel of a thread. We should have several threads - General FAQ's K horn FAQ's La Scale FAQ's etc Amplification FAQ's CD FAQ's etc. Doing a general search of FAQ should catch all of them. Liek I said, the biggest problem I see is non-essential posts. Can amy or trey lock posts to just one user? One of you "Cry for help" or above guys can be the impartial post what is generally agreed upon gatekeeper. I think teh first step is to come up with the initial threads to use. Just some thoughts, Chris PS: Sorry to hijack the thread if this occurrs. Thsi can be moved to a new thread. EDIT: My vote for the person with the power to post to the thread is William McDermont. He does not build any equipment and has contributed a huge amount of information through his efforts for the general good of all of us. I think that this shoudld be considered an honor by the way (kind of a respect from all of us thing). Quote Link to comment Share on other sites More sharing options...
Deang Posted July 16, 2005 Share Posted July 16, 2005 Bob -- sure, that would make sense, and we'll assume that's the case. However, that's really not what I'm asking. Look at it like this then: If we are using the T2A, on tap 4 the reflected impedance is roughly 32 ohms, and the primary cap is sized for that impedance (actually 29.5 ohms). If we drop the squawker to tap 3, the reflected impedance doubles, and we size the primary cap accordingly (6.8uF). The 3db reduction changes the cap value, so, why not a 1db reduction? Chris, let's save the FAQ thing for another thread and keep this one for the autoformers. In fact, we actually had a huge FAQ thread a couple of years ago over on two channel, I'll see if I can find it. Quote Link to comment Share on other sites More sharing options...
tigerwoodKhorns Posted July 16, 2005 Share Posted July 16, 2005 ---------------- Chris, let's save the FAQ thing for another thread and keep this one for the autoformers. In fact, we actually had a huge FAQ thread a couple of years ago over on two channel, I'll see if I can find it. ---------------- Agreed, I am interested in the autoformers and will be watching this thread. Chris Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 16, 2005 Share Posted July 16, 2005 Well, you can't blame Klipsch for not helping with aftermarket mods. If they did they'd be flooded with people asking for free engineering work. "What if I do this, that, or the other thing. Please test it and give me the results." As mentioned, the values of components in a crossover do depend on the load. The auto transformer does alter the load. I believe you can do some reasoning to infer the load. For example. The power is V*V/R. Therefore, if there a 3 dB loss, there must be twice the resistance of the driver reflected seen at the input to the autotransformer. If there is 6 dB loss there must be 4 times the impedance of the driver. Get out your calculators or slide rules. I'm a fan of Al K.'s design with the swamping resistor. In that the crossover filter is looking at the combined parallel impedance of the resistor and the autotransformer. Generally the autotransformer presents a relatively high impendance even at 3 dB. Then it becomes higher as attenuation (by tap selection) goes up. Hence the resistor swamps out variations due to the autotransformer. It dominates the value of the parallel circuit. Variations in the raw driver impedance are reflected back through the autotransformer too. These are swamped out too. Best, Gil Quote Link to comment Share on other sites More sharing options...
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