whell Posted July 28, 2003 Share Posted July 28, 2003 Yet another thread where one forum member tries to prove that his output tube is bigger than someone else's. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 28, 2003 Share Posted July 28, 2003 The cathodyne will probably give you the best unloaded voltage balance but it still have one important problem. The output impedance will be much higher for the plate circuit than for the cathode circuit. So in the end your still stuck with problems. Williamson partially soved this by usig a combo cathodyne and a diff amp. The cathodyne splits phase with near perfect balance, but it drives an easier load than pp power tubes grid. There is no such things as free lunch. Amen to that I myself would much rather have a phase setup that I could achieve perfect balance with and without a AC balance function its just not possible ! Ryan, I believe that the only difference seperating these amplifiers sound wise is the phase splitter/driver. You better look at the 2 schematics again they are far from the same ! It really doesn't matter to me one way or the other what phase setup you like. I myself have tested different 6U8's in the cathodyne setup and receives varying results with every tube installed its does not do a perfect phase inversion ever its close but not perfect. Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 28, 2003 Share Posted July 28, 2003 Ryan, What you just wrote was compeltely redicules what do you think were talking about here ? What exactly do you think the scope shows ??? This amplitude has to be Identical going to each tube of the pair or distortion will happen especially at higher output. Your assuming that everything would be perfect throughout the entire phase circuit and its not this is why AC balance is better fire up your amp and put a few random but test good 6U8's in and check the AC signal running into each tube of a Channel closely I can guarantee it will vary from side to side and from tube to tube. There are just to many variables there for it to work absolutely perfect. I've done my home work on this not by reading or spouting off what I think should be perfect I used my scope. I was prodded by Mark Deneen to do so. I know for a fact that he agrees AC balance is always better ! Oh indecently AC Balance could be incorporated into your Cathodyne Phase setup ! Scott just pinched some pennies because indeed that circuit gets it pretty close but NOT PERFECT. Your explaination of Class A/B operation is way off. The lower you run the plates toward class A and the higher you run the Bias the longer the amp stay's in Class A the reverse is true by raising the voltage and lowering the bias. Look at the Tube data !! I never said that a 299 was in class A but a amp can be bias to lean closer to A or B in Push pull AB operation I can not believe you don't know this. how many time have I heard you recommend people run there 222D's at 46Ma rather than 44Ma to KEEP THEM IN CLASS A LONGER ?? To put a 7189 in Class A output you lower the plate voltage and RAISE the Bias setting to put it closer to class B you raise the Plate Voltage and lower the bias. The screen voltages have to be adjusted also. I have run a 222C in Class A triode before and yes a wattage hit was extreme. I guess you forget that I spent about 6 month playing with one until I found that the 299A/B were better made amps. There are many differences between the amps besides Xmas tree lights and if you don't know it I'm truely worried about you ? Craig Here is a schematic to run any EL84 in class A triode you will notice you lower the Plate and raise the Bias !! Exactly what is done to the 299A/B compared to the 222C/D Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 28, 2003 Share Posted July 28, 2003 Oh and this statement is just crazy !! If you view with an oscilloscope an unloaded paraphase circuit, the results are much different. The amplitudes of each signal are not matched, however, they are split 180 degrees. Even adjusting the AC Balance pot will not get the amplitudes equal. When the paraphase is loaded with the 7189 grids, and by adjusting the AC Balance, complementary signals are possible. Clearly, the cathodyne is the more stable circuit in this application, even unloaded (with just the load of an oscilloscope). I can't say the same for the paraphase, as when it is unloaded, it is unstable (and doesn't act as a good phase splitter). The paraphase works, but it is just too picky. Who the hell cares what the unloaded circuit looks like what matters is what it does in true operating condition. I have never had even the least trouble getting absolutely perfect phase inversion with a 299A/B on every amp I have done. Your just talking total nonsense here. This is not the case with the 222c and above its always off sometimes very small other are substancial it depends on the tube and a chance perfect match up that never happens. It does a commendable job but NOT PERFECT. Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 28, 2003 Share Posted July 28, 2003 Ryan, What exactly is your problem ? Is the only way you can discuss anything is to insult people and spread complete confusion. You need to go back and hang out exclusively on the Scott forum where your protected from any criticism because its pretty obvious you can not stand someone that disagrees with the almighty word or has a different opinion then Ryan Inman. You have no clue what your talking about and now your going to start insulting Mark Deneen because he doesn't agree with you ? Its really to bad he isn't here at the moment to defend his fine reputation on this board. Oh and he is who wrote that schematic its really to bad you don't understand it. Your just not worth all this !! Craig Quote Link to comment Share on other sites More sharing options...
mike stehr Posted July 28, 2003 Share Posted July 28, 2003 Gee, I thought you didn't want to go past 80% of the tubes total dissipation factor. WTHFDIK.... Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 28, 2003 Share Posted July 28, 2003 Ryan, BTW: I don't have a problem with facts, but you have yet to provide any. Why didn't you catch this?? Neither have you and like I said your just not worth it ! You have this twisted Idea that your opinion is fact. I have went through this type of thing many times with you and provided facts and you just twist them around and come from a different angle. Your just not worth it ! Mike, Gee, I thought you didn't want to go past 80% of the tubes total dissipation factor. WTHFDIK.... Obviously more than Ryan Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 29, 2003 Share Posted July 29, 2003 Plate dissapation on a Push/Pull AB1 7189 is actually 13.2 Watts ! Not 12 watts. All Scott 7189 amplifiers have an output of 24W. Should they have used the 80% derating factor, yes. But they wanted the 24W. 7189 Based amps The 299A puts out 17 watts RMS (steady state) (40 Watts total music waveform of peak both channels) The 299B puts out 21 watts RMS (steady state) (50 Watts total music waveform of peak both channels) The 222C puts out 20 Watts RMS (steady state) (48 Watts total music waveform of peak both channels) The 222D puts out 2o Watts RMA (steady state) (50 Watts total music waveform of peak both channels) 6BQ5 based amps The 222A puts out 13 watts RMS (steady state) (30 Watts total music waveform of peak both channels) The 222A puts out 13 watts RMS (steady state) (30 Watts total music waveform of peak both channels) They are not all the same !! Quote Link to comment Share on other sites More sharing options...
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