KSA50 IQ about 2.5 A.
They will be divided into two or so share to four only diode. Common silicon diode voltage should be in 0.55 V.
Rectifier diode general fever should be approximately 1.25 * 0.55 * 4 = 2.75 watt
Although there will be some hot but not be damaged. The best way is to the tube mounting a tiny radiator, we can ignore the existence of the diode.
"Krell used a 400va transformer per channel, ie two per stereo chassis. In the course of production they used both toroids and EI transformers so no big deal there.
A normal KSA50 channel has ~37v rails. This requires 2 secondaries at ~26v AC, or 52v center tapped. A minimal transformer for two channels would be about 400va, you'd want more for driving low impedance loads." Thus my confusion... :/
A normal KSA50 channel has ~37v rails. This requires 2 secondaries at ~26v AC, or 52v center tapped. A minimal transformer for two channels would be about 400va, you'd want more for driving low impedance loads." Thus my confusion... :/
For ClassAB stereo, a 400VA transformer would be suitable for 200W to 400W of total maximum output power.
If the KSA50 is guaranteed to provide 50W into 8r0 when mains is at supplier minimum. Yes, that is why when tested on an accurately set nominal supply voltage, they always measure far higher.
Then with the same low supply voltage you would expect slightly <100W into 4r0. That meets the more stringent spec of max P ~half VA.
Similarly expect a bit less than 200W into 2r0. That meets the more relaxed spec of max P ~ VA.
So the 400VA for a pair of KSA50 indicates a minimum resistive load somewhere between 2r0 and 4r0.
I would check that by setting out a testing procedure using nominal supply voltage and measuring dBV for resistive test loads of 8r0, 4r0, 3r3, 2r0, 1r7 and from there determine where the -0.5dBV lies and also where the -1dBV lies.
Only then could I assess the ClassAB capability of the stereo amplifier powered by a 400VA transformer.
But, KSA50 is a ClassA amplifier designed for 8ohm speakers that happens to drive 4ohm speakers rather well.
We are in a completely different ball park from ClassAB design brief.
If the KSA50 is guaranteed to provide 50W into 8r0 when mains is at supplier minimum. Yes, that is why when tested on an accurately set nominal supply voltage, they always measure far higher.
Then with the same low supply voltage you would expect slightly <100W into 4r0. That meets the more stringent spec of max P ~half VA.
Similarly expect a bit less than 200W into 2r0. That meets the more relaxed spec of max P ~ VA.
So the 400VA for a pair of KSA50 indicates a minimum resistive load somewhere between 2r0 and 4r0.
I would check that by setting out a testing procedure using nominal supply voltage and measuring dBV for resistive test loads of 8r0, 4r0, 3r3, 2r0, 1r7 and from there determine where the -0.5dBV lies and also where the -1dBV lies.
Only then could I assess the ClassAB capability of the stereo amplifier powered by a 400VA transformer.
But, KSA50 is a ClassA amplifier designed for 8ohm speakers that happens to drive 4ohm speakers rather well.
We are in a completely different ball park from ClassAB design brief.
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