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In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET

Post Subject: A word of warningPosted by Romy the Cat on: 6/25/2015

anthony wrote:
In the 6 Channel Version of Super Melquiades thread at post #89 you mention trouble you were having with some NC relays that you were using to disconnect some power supply bleeder resistors when the amp was turned on. When the amp is turned off these relays make contact again and they conduct power to drain the power supplies backwards into high wattage 50R resistors. I can see that this would be a good idea from both safety and cap lifespan perspectives. Could you please share a little more info about this setup? Does it still function? You mention 50R resistors and bridging two 6A relay contacts for each power supply. What wattage do you use for the resistors?

I do not remember the specifics with relay. The driver and bias PS are bled the 6C33C’s PS are not. You might do it if you want. You can do it while the PS is running, that would require some current from transformer to be wasted and I do not know if you have a spare current in there. Also, the elevated current would drive the minimum inductance down and would make your choke to be smaller. You can do alternative and on back side of relay to connect a high power resistor, let say 50W. This all does not matter, you can do whatever you want. Just a word of warning if you use the full-range Milq as reference. In the PS of the driver stage it shown L1 20H. For the 100mA the 20H is barley hit the critical inductance. When I measured the critical inductance it did worked fine but to be at the save side I would go ether with let say 30H choke or to drive over the choke 30-50mA more (can be easily set by dropping the volume of R23 resistor). It is not a big deal but it will be more of save side if you do.

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