Search found 140 matches

by nanana
Fri Feb 05, 2021 3:42 pm
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

i am in agreement with this... we are saying mainly the same thing with different terms. differential = common mode. the primary turns of the output transformer can be less than optimum because the chokes boost the load for the 2A3s. an economical tranny for bass. and a small economical one for the ...
by nanana
Fri Feb 05, 2021 11:17 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

like this... i get it. i don't think it's got anything weird going on. note the small size of the caps! i am sure the output trans on top could be optimized for minimum L to save money.
by nanana
Fri Feb 05, 2021 10:47 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

if the grids get balanced drive there is no difference between a common mode choke and two separate chokes. or a center tapped choke. but in a balanced system, if there is unequal loading or drive, some error correction is forced upon the whole.
by nanana
Fri Feb 05, 2021 10:27 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

the cost of insertion loss is HIGH with a common mode choke. but for loading purposes, you get a lot more bang for your buck! using this technique is very interesting.
by nanana
Fri Feb 05, 2021 10:24 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

here it is. note that the inrush current is completely regulated in the AC common mode choke. the choke input, with DC component, "swings". and the pi filter has an extra cap and does not regulate. the ripple is clearly lowest in the AC filter, and the pi filter has more C! but the choke d...
by nanana
Fri Feb 05, 2021 10:20 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

i keep getting the sizing stuff wrong for this format... too big or too small!
by nanana
Fri Feb 05, 2021 10:17 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

here are the sweeps. the top is obviously pi filter. the middle is conventional choke input. and the bottom is AC choke. each is 1H each winding, common mode (coupled). so there is almost double the drop of a conventional choke input, but more regulation. this action takes cost away from the output ...
by nanana
Fri Feb 05, 2021 10:11 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

below i add an experiment i did to test the relationships between "critical inductance", capacity and load. this is for power supply purposes but the idea is universal. i wanted to know what the effects were to work strictly in the AC realm. i wanted to put the choke ahead of the rectifier...
by nanana
Fri Feb 05, 2021 9:17 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

i think it is important to pay attention to Klipsch's initial statements about low cost. large value caps cost more than transformers at that time, and perform poorly. a low turns ratio transformer together with a 1:1 common mode choke gives a higher performance per dollar... at that time. the commo...
by nanana
Fri Feb 05, 2021 2:27 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

because its low frequencies! and the windings are coupled... bifilar on the same core is a common mode choke. a 1:1 transformer functions exactly the same. you will not get much high frequency left on the other side but that is the point! the clever part isn't that. i don't think...? it's the simple...
by nanana
Fri Feb 05, 2021 1:52 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

i do see the cleverness of loading the triodes with both L1 - L2 AND the output transformer! you can use less inductance in the output primary and still get good loading for the low end... because the common mode choke is also part of the load. very slick!
by nanana
Fri Feb 05, 2021 1:49 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

i imagine also that L1 - L2 are hum bucking... these chokes would otherwise be very sensitive to hum pickup. by making them bifilar, and common mode, you get hum rejection. very useful in a low frequency crossover!
by nanana
Fri Feb 05, 2021 1:45 am
Forum: Circuits
Topic: Klipsch woofer - tweeter crossover network.
Replies: 29
Views: 49285

it's clear that L1 - L2 is a common mode choke. as soon as you hear that it simply means a balanced network, and not common ground. that makes the crossover much simpler. the bass is a balanced 2nd order filter and i love the idea of incorporating it on the high Z side to avoid large value caps... u...
by nanana
Fri Jan 22, 2021 9:40 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

also, i know the formula for triode follower gain ends up at around "0.9". it is NEVER that high in reality. it's always less, unless there's gain somewhere else. low mu in a triode with the normal loss of gm with aging, in particular, really bleeds gain. most CFs are 0.8, or even a bit le...
by nanana
Fri Jan 22, 2021 9:33 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

output Z is inversely proportional to transconductance in tetrodes/pentodes, and a ratio in triodes. high gm is low Z. in the transition from A to B, it's going to be Z/2, to a bit more than Z, as only one tube is on at a time... so you already know the answer to your question. but there's a wrinkle...
by nanana
Fri Jan 22, 2021 3:36 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

i have a pair of M7s! it does sound perfect for this...
by nanana
Fri Jan 22, 2021 3:35 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

the mu in tetrode operation is much higher, so there is more internal feedback. it isn't the same! transconductance does matter for a follower, but most important for insertion loss is mu. this is why 5687's are such lousy cathode followers all by themselves, and 6922s or 6C45Ps are such excellent c...
by nanana
Thu Jan 21, 2021 10:42 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

just to summarize a few important things, the bifilar unity coupled circuit is definitely based on the split load inverter. in push pull, 2 inverters can work well in class B... the coupling between the windings is also a feedback system, besides the degenerative fb inherent in the split load. the s...
by nanana
Thu Jan 21, 2021 10:33 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

here's the output sweep
by nanana
Thu Jan 21, 2021 10:32 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

here's the output
by nanana
Thu Jan 21, 2021 10:30 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

here is the circuit with 350V supply and 60mA per tube. class A - AB old school. with 240 pp input and into 8 ohms, about 12 watts, no additional error correction... you can see the onset of clipping just coming in the current waveforms of the windings... it looks horrible! output distortion just ov...
by nanana
Thu Jan 21, 2021 9:48 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

the green is the plate winding, you can see the clipping caused by the peaking screen on the opposing side. and yet in the cathode (the blue trace), the subtracted third from the sine... (tall and narrow). this is the power of feedback. the sum of these is a near perfect sine of current in the 2.5K ...
by nanana
Thu Jan 21, 2021 9:46 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

whoops! here it is...
by nanana
Thu Jan 21, 2021 9:45 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

here is another money shot... from your circuit! i increased the voltage to 400 volts because this 6L6 model just doesn't have enough cajones at 350... i reduced the inductance to 10 H each winding. i increased the screen current limiting resistors to 500 ohms. 2.5K gives the same current in the loa...
by nanana
Thu Jan 21, 2021 9:29 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

in any case, i think the mystery is solved. the unity coupled output stage is very good. and very interesting! and i see NO reason to use it only in class B. wtf! other than economy? it's an inefficient circuit because of the 100% feedback. it is applied just like a cathode follower. it takes a lot ...
by nanana
Thu Jan 21, 2021 9:19 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

actually the 2 K load draws 4 times the current! so the output Z is very low!
by nanana
Thu Jan 21, 2021 4:07 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

oops. here's the corrected image. i loaded the secondary with enough to draw the same current as any other single winding. it works... but the inductance should be reduced to between 6 and 10H.
by nanana
Thu Jan 21, 2021 4:04 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

i replaced the 6L6GC model with a plain vanilla 6L6 version. the 6L6GC oscillated and did weird stuff. the 6L6 works fine. you have the screens reversed. and the inductance is WAY WAY too high. it still works but slews like crazy.
by nanana
Thu Jan 21, 2021 3:59 pm
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

the screens are hooked up backwards.
by nanana
Thu Jan 21, 2021 8:32 am
Forum: Circuits
Topic: Mac Unity coupled
Replies: 88
Views: 32429

in terms of output impedance, the next test will be voltage changes with load changes at high frequencies... but the magnitude isn't going to be large. one can already see that in the 8 ohm load. the peak current is the same, although the duty cycle is changed by some percent. a modest rise. but i w...