Randall Diavlo RD45 - Suitable For 240v Mains Conversion?
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- เผยแพร่เมื่อ 3 ก.พ. 2025
- Here the customer has requested a price for conversion to 240v mains input. This can be a simple rewiring of the primary, or can require complete replacement of the power transformer, depending on the amp model.
What a bummer. Hope it is worth fixing.
It also occurs to me that having just one style of universal AC power cord jackis probably a bad idea for any device that requires a rewiring of the transformer internally in order to run on different voltages. There's nothing that stops a person who doesn't know any better from just grabbing a new power cord that has the same connector for the amplifier but matches the socket in the wall for a given country and thereby putting 240 V on a 120 V designed device, or vice versa. Perhaps the IEC power inlet jack on the back of the amplifiers should have 4 or 5 pins; in this way an amp could be designed so that it won't run at all with the incorrect cord and incorrect inputt voltage; or perhaps a mutivoltage transformer could be connected to all of them and when you select the proper cord (with a plug matching the local wall sockets) it will automatically deliver the correct voltage to the relevant transformer windings....
Do my eyes deceive me or does that amp have a shrinkwrapped thermistor bundled up with the input AC wiring? That is a stupid f---ing way to do it; the heat from the thermistor is bound to bake, deteriorate, and perhaps melt the wiring. It's also sitting right next to the filter caps, which have to deal with the additional heat. I'd mount that thing to the chassis. Some manufacturers put the thermistor on the circuit board but that tends to degrade the solder connections pretty quickly. And for those who don't already know this, a thermistor is a special type of resistor, typically wired inline in series with the incoming AC voltage; a thermistor is the opposite of ordinary resistors,, and has maximum resistance when cold but minimal resistance when it heats up. An inline thermistor reduces voltage and current surges to the components when it is cold, but it heats up as the amp operates and its resistance goes down to minimum so that it is almost out of the circuit. They do get quite hot in operation. Blistering hot, usualky!
Great observation.
@@fiddlix , for that matter, adding a thermister to old amps that are now now running at such high voltages that that the tubes are stressed isn't really a bad idea but it really should be done neatly and witout major mechanical and electrical modification. Mounting it to the chassie where it can't burn anything and can dissipate a little heat would be a good idea period of course before you do anything else you would want to make sure that the original filter caps have been replaced and upgraded in such a way that the power supply can handle excess voltage with or without a thermistor. And then you have to worry about proper biasing and plate dissipation and using high quality tubes. There's no reason why a thermistor couldn't be part of that equation *once everything else has been taken care of 1st.*
@@goodun2974 Agreed 100%. I hope there is a part 2 to see the final outcome.
It's not surprising they didn't use a switchable/selectable-voltage transformer; those things cost money. Only the *chassis* and silkscreening are voltage-compatible worldwide!
Just go ahead and plug the amp directly into 240 Volts. So it runs at temps resembling Dante's 7th level of Hell, so what? As the old saying goes, the Diavlo is in the details!🥵😡💥