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RE: Send Ian Grant at Grant Fidelity an email................

So here is the maths involved, assuming 6V heaters:

110V supplied 110V transformer gives heater tap of 6.3V.
120V supplied 110V transformer gives heater voltage of 6.87V.

Doesn't seem too bad, but wait: 110V 50Hz transformers are slightly more efficient at 60Hz and this is why you will see even higher heater voltages.

Translate this to HT: 420V DC on 110V supply translates to 458V DC when running on 120V. When you are using 450V capacitors, this is a fire hazard. Period.

Mains at my house is often around 123V. Figure that one out... Heater voltage 7.04V, HT voltage 469.6V. Imagine where the bias point is for those who don't know how to bias their own amps! What about max operating points for the tubes?

Now we have importers saying their amps are specified for 115V +/- 10%. This is generally not true. The target voltage for the transformers is generally 110V NOT 115V. Saying they are for 115V +/- 10% effectively says they can handle a voltage range up to 126.5V WITHOUT DAMAGE.

Try it. Connect your Chinese amp that has a 110V or 115V sticker on the rear to the mains. Measure the heater voltage. Record the results on this forum. That way we'll find out who is going to the trouble of bringing in safe electronics and who is not. Come on. I dare you all.



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  • RE: Send Ian Grant at Grant Fidelity an email................ - raindances 11:23:31 02/23/10 (0)

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