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In Reply to: RE: Choke power supplys in Comp Symmetry BJT power amps posted by grhughes on August 19, 2011 at 08:00:32
DJK is right. Ayre used choke-input power supplies in our original five products, of which two were power amps. The cost of the power supply (which is a significant fraction of the entire product is doubled. Plus high-powered chokes create a high-powered mechanical buzz that customers hate.
There are other ways to skin that cat that don't have the drawbacks of chokes. Please also note that there is a BIG difference between a true choke-input power supply and a power supply with a choke. The latter is more of a gimmick, created largely to give the marketing department something to spin.
Follow Ups:
Single unit with two windings - Does this make any sense?
Was as big as the power transformer itself.
No idea of the millihenry? value. Contacted the manufacturer with the part number but they wanted $1000 to search their files!
Charles
Hello,
I am planning to order the latest virtue amp called the threee as soon as it is available. In the past i did have an hiraga solid state amp with did use 200mh 2.5A 1ohm chokes in the power supply. I wanna try to make a single rail power supply for the three. I did ask some questions on the virtue site but no answers so far.
If i remember correctly the best supply would use 4*12 volts battery to get 55 volts or a 48 volts switching power supply.
I have a transformer that has a secondary winding rated 39 volts at 9 A. Hammond does have some high current chokes but i don't know if they have enough inductance to make a true choke input power supply. I think the current drawn by the amp will not be stable like an hiraga amp. So maybe first a cap after the rectifier. Anyone likes to share some ideas? Greetings, Edward P.s i do have some 400 millihenry 2 A 4.2 ohm chokes but i think their resistance is to high. Hammond has an 150mh 3A and 1 ohm.
"Please also note that there is a BIG difference between a true choke-input power supply and a power supply with a choke. The latter is more of a gimmick, created largely to give the marketing department something to spin."
This is truer for a lower impedance high capacitance PS for SS and OTL amps. For high impedance amps, OPT style tube amps, the CLC filtered L component is much more useful: smaller lower current chokes, a higher order and more complete filter for 100-120 Hz as especially SET amps have poor PSRR. Less important always with balanced design.
nt
"The gift of imagination is a gift of the Gods imparted to a few who receive innumerable kicks in the a$$ their entire life." LeCorbusier (Edward Jenneret)
No, but it's the same principles applied. The critical inductance, the voltage expected with margin, the regulation improved, etc. The complete formula never changes, but the values entered will. Then there's practical matters. For a complete analysis, simulators can show a lot in the different cases.
For one case, use typical tube PS LC values. For a given sized current draw and capacitance in the PS, change the values expected for a SS amp, too. Try different values and see the simulated results. Do not forget to put in the correct R values in the L's.
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