captainbeefheart Posted November 30, 2021 Share Posted November 30, 2021 28 minutes ago, mboxler said: Would you please post one of the LTspice models? Also, I'm not a bat 🦇. Could you end your simulation at 20000 hz? My simulation is quite a bit different. Thanks, Mike First is Tiz's values Second is stock values Third sim Changed scale up to 20kHz max Quote Link to comment Share on other sites More sharing options...
Dave A Posted November 30, 2021 Share Posted November 30, 2021 3 hours ago, Curious_George said: If for some reason, you are not skilled, there is always another hobbyist willing to help. HA HA back to rookie school 101 for YOU Dean. 1 hour ago, Marvel said: I'm sorry, but that right there is funny. No it is hysterically funny. As an aside here I don't remember reading of so many ways to complicate an AA crossover recap job in a long time. Quote Link to comment Share on other sites More sharing options...
mboxler Posted November 30, 2021 Share Posted November 30, 2021 25 minutes ago, captainbeefheart said: First is Tiz's values Second is stock values Third sim Changed scale up to 20kHz max Okay, I saw this earlier but never commented... The simulation of the autoformer isn't quite right. There are a few good models, this is the one I came up with. The autoformer is one big tapped inductor, not several inductors in series. You will notice the K directive. It tells LTspice to mutually couple all the series inductors. The total inductance of my model is around 44mh, tap 0 to tap 5. Quote Link to comment Share on other sites More sharing options...
captainbeefheart Posted November 30, 2021 Share Posted November 30, 2021 23 minutes ago, mboxler said: Okay, I saw this earlier but never commented... The simulation of the autoformer isn't quite right. There are a few good models, this is the one I came up with. The autoformer is one big tapped inductor, not several inductors in series. You will notice the K directive. It tells LTspice to mutually couple all the series inductors. The total inductance of my model is around 44mh, tap 0 to tap 5. I have my all my directives listed away from the schematic to clean things up including the K I place the DCR in the inductance model, it just isn't seen on screen Quote Link to comment Share on other sites More sharing options...
captainbeefheart Posted November 30, 2021 Share Posted November 30, 2021 27 minutes ago, mboxler said: The total inductance of my model is around 44mh, tap 0 to tap 5. The autoformer total inductance is 42mH Each tap is reduced by -3db Inductance is a squared function Inductance going from -3db onward would roughly halve looking at it from first tap to each attenuation tap; -3db= 21mH -6db=10.5mH -9db=5mH -12db=2.5mH But you don't write it in this way, each tap needs to be it's own inductance value, not the value from first tap to each individual tap like as i listed above. Quote Link to comment Share on other sites More sharing options...
captainbeefheart Posted November 30, 2021 Share Posted November 30, 2021 I messed up and forgot a tap, I only have 4 inductors, I will add the fifth. It still dropped -3db but the total inductance is only 21mH in my model and with the next tap will be 42mH. Quote Link to comment Share on other sites More sharing options...
captainbeefheart Posted November 30, 2021 Share Posted November 30, 2021 Basically if you want to increase by 3db it is roughly 1.41, so that is the turns ratio. The inductance/impedance ratio is a squared function or 1.98 Look at it backwards; 2.8mH * 1.98= 5.4mH 5.4mH*1.98=10.9mH 10.9mH*1.98-21.73mH 21.73mH*1.98=43mH Quote Link to comment Share on other sites More sharing options...
mboxler Posted November 30, 2021 Share Posted November 30, 2021 Sorry if I'm not following your math. Let's say the inductance between tap 0 and tap 5 is 43mh. Also, keep in mind that tap 4 on the T2A is actually -3.35db, 10 volts in = 6.8 volts out. Taps ratio of total turns Ratio of total inductance 5-4 .32 .1024 or 4.4032mh 4-3 .18 .0324 or 1.3932mh 3-2 .144 .020736 or 0.891648mh 2-1 .106 .011236 or 0.483148mh 1-0 .25 .0625 or 2.6875mh Not sure if this gets us on the same page, but I tried. Mike Quote Link to comment Share on other sites More sharing options...
Deang Posted December 1, 2021 Share Posted December 1, 2021 3 hours ago, Dave A said: HA HA back to rookie school 101 for YOU Dean. No it is hysterically funny. Yes, it is! These days it’s almost more fun just to sit and enjoy the show. 1 Quote Link to comment Share on other sites More sharing options...
captainbeefheart Posted December 1, 2021 Share Posted December 1, 2021 56 minutes ago, mboxler said: Sorry if I'm not following your math. Let's say the inductance between tap 0 and tap 5 is 43mh. Also, keep in mind that tap 4 on the T2A is actually -3.35db, 10 volts in = 6.8 volts out. Taps ratio of total turns Ratio of total inductance 5-4 .32 .1024 or 4.4032mh 4-3 .18 .0324 or 1.3932mh 3-2 .144 .020736 or 0.891648mh 2-1 .106 .011236 or 0.483148mh 1-0 .25 .0625 or 2.6875mh Not sure if this gets us on the same page, but I tried. Mike Let's simplify the model between inductance and turns. Let's say the total inductance of the entire winding is 44mH to make math easy If you place a center tap it would be half the turns ratio, but each side of the center tap is not 22mH like you would think, they would be 11mH because of the squared function. Quote Link to comment Share on other sites More sharing options...
captainbeefheart Posted December 1, 2021 Share Posted December 1, 2021 editing- I am trying to do other work while I think of this and I am old!!! 👴 Once I finish up I will help dissect and explain the exact individual inductances and not the total inductance between each tap(1-5) to tap 0. With 10vac at input, across pins 0 and 5, you will get 10vac or 0db attenuation if you take the output from pin 5. Each tap down 4,3,2,1 are increments of -3db. We want to put into the simulator each of those individual inductance values. Quote Link to comment Share on other sites More sharing options...
mboxler Posted December 1, 2021 Share Posted December 1, 2021 1 hour ago, captainbeefheart said: Let's simplify the model between inductance and turns. Let's say the total inductance of the entire winding is 44mH to make math easy If you place a center tap it would be half the turns ratio, but each side of the center tap is not 22mH like you would think, they would be 11mH because of the squared function. Agree! Taps 0 - 3 equals one half, or 5/10 of the total turns. So...(5*5)/(10*10) = 25/100 = .25 44mh * .25 = 11mh. I can do the same everywhere. Taps 5 - 4 equal 3.2/10 of the total turns. (3.2*3.2)/(10*10) = 10.24/100 = .1024 44mh * .1024 equals 4.5056mh Taps 4 - 0 equal 6.8/10 of the total turns. (6.8*6.8)/(10*10) = 46.24/100 = .4624 44mh * .4624 equals 20.3456mh If you really want easy -3db, use 2.93/10 for taps 5 - 4 and 7.07/10 for 4 - 0. We're probably stating the same thing in different ways (Isn't math great)! Mike Quote Link to comment Share on other sites More sharing options...
captainbeefheart Posted December 1, 2021 Share Posted December 1, 2021 2 hours ago, mboxler said: Agree! Taps 0 - 3 equals one half, or 5/10 of the total turns. So...(5*5)/(10*10) = 25/100 = .25 44mh * .25 = 11mh. I can do the same everywhere. Taps 5 - 4 equal 3.2/10 of the total turns. (3.2*3.2)/(10*10) = 10.24/100 = .1024 44mh * .1024 equals 4.5056mh Taps 4 - 0 equal 6.8/10 of the total turns. (6.8*6.8)/(10*10) = 46.24/100 = .4624 44mh * .4624 equals 20.3456mh If you really want easy -3db, use 2.93/10 for taps 5 - 4 and 7.07/10 for 4 - 0. We're probably stating the same thing in different ways (Isn't math great)! Mike Yes same thing different math to show it. BUT, we need the individual values of each "inductor" So the halfway tap (0-3) we have each side totaling 11mH giving a total winding inductance of 42mH. 11/4=2.75mH ^^^This would be cutting the halfway points in half again down to a value of 2.75mH each "inductor", I just used 2.8mH instead of 2.75mH because that is what the actual autoformer measures because the total winding inductance is closer to 43mH-44mH. Quote Link to comment Share on other sites More sharing options...
Deang Posted December 1, 2021 Share Posted December 1, 2021 The autoformer isn’t even part of the tweeter circuit. Why do we care about this? Quote Link to comment Share on other sites More sharing options...
Curious_George Posted December 1, 2021 Share Posted December 1, 2021 15 minutes ago, Deang said: The autoformer isn’t even part of the tweeter circuit. I guess this falls under “observation”. 1 Quote Link to comment Share on other sites More sharing options...
captainbeefheart Posted December 1, 2021 Share Posted December 1, 2021 20 minutes ago, Deang said: The autoformer isn’t even part of the tweeter circuit. Why do we care about this? The discussion about the different tweeter network values led to a simulation of the entire network which led to a question about the simulation. A little sidetracked but in my opinion a good sidetracked, some folks want a better understanding of the entire filter network and the autoformer is often misunderstood. We can steer this train back to the tweeter you watch 😜 Quote Link to comment Share on other sites More sharing options...
mboxler Posted December 1, 2021 Share Posted December 1, 2021 29 minutes ago, Deang said: The autoformer isn’t even part of the tweeter circuit. Why do we care about this? My fault. I noticed differences in the plots and was curious why. Although the major difference had to do with the load resistor (I use 8 ohm), I couldn't help but notice the autoformer model difference as well. Apologies to the OP. Mike Quote Link to comment Share on other sites More sharing options...
Deang Posted December 1, 2021 Share Posted December 1, 2021 35 minutes ago, Curious_George said: I guess this falls under “observation”. I remember the context of that, do you? Quote Link to comment Share on other sites More sharing options...
Deang Posted December 1, 2021 Share Posted December 1, 2021 22 minutes ago, mboxler said: My fault. I noticed differences in the plots and was curious why. Although the major difference had to do with the load resistor (I use 8 ohm), I couldn't help but notice the autoformer model difference as well. Apologies to the OP. Mike it was a sincere question. Quote Link to comment Share on other sites More sharing options...
henry4841 Posted December 1, 2021 Share Posted December 1, 2021 9 hours ago, mboxler said: We're probably stating the same thing in different ways (Isn't math great)! Mike Reminds me of the great mathematician chess player Emanuel Lasker who said there is always another mathematician that claims to have a better solution to a mathematical equation but in chess I just checkmate them. For chess lovers the Chess championship is happening right now in Dubai and is available on youtube. Carson vs Nepomniachtchi. All ties so far. Quote Link to comment Share on other sites More sharing options...
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