Review of a Chinese amplifier, Nobsound 6P1. Schematic Review - Part 3 

I like that (sarcasm) "that I should stop being troublesome. " . REALLY!?! Oh well. It is AliExpress and many of the vendors do not really understand the expectations of the western world. But they are learning. You were not unreasonable, the seller did not want to disclose the truth "...the difference between the 220v, 230v and 240v variants is...the sticker glued to the transformer." This is why product standards are developed. But if this or any other product continues to be of interest, I would suggest a variable transformer (VARIAC) and set it to the voltage you want. This one is interesting and it has a voltage meter for the output! www.ebay.co.uk/itm/282760979817?hash=item41d5de2569:g:V00AAOSw6clgetlX&amdata=enc%3AAQAHAAAAoPNdTm6dzxVRIgQDYsKftjMFWyX6ExTSneQMUSWH1CuxZUnjCPnchi0TJFk75yEZJRNRi3SwYp7Z1vaSPHZbfseF5Q9n7R52UHcY1PXmUC4EBXznZeg1LyNa3XeUDZebAgHMYgLpq%2B%2BAs9lq1nt57invAF4xbMC81CUDI%2Bp1MO%2FNt10J3L8ZzZR%2FwMAUmUV2fvZw8Lmlx2JdRt0vl7RIkfY%3D%7Ctkp%3ABk9SR7KO5MDSYQ It is a bit ugly but... If you had a preamp that was 220v you could use a power bar to run your 220 volt equipment. I believe the Chinese use a 110/220 volt system and the vendor is just trying to get a larger market. Good luck and I hope you find a suitable product. Cheers.

Thank you. 110 volts is standard in many many countries so that is why the designer chose that value. Tolerances are usually +/- 10% but in the US and Canada 120 is standard which is on the very top end of 10%. At my home the voltage at the outlet can be as high as 128 volts. Well within the acceptable range for utility supply. 128 volts may be a problem for this amp. The concern is to keep the B+ voltage down as some of the tubes are getting close to the maximum plate voltages. So really, this is just a safety thing. Just plugging the amp in will still be OK. I did not get my amp from Nobsound. I purchased it from Aliexpress and it came from China under the name of Sunbuck. It was on sale! :) I suspect that Nobsound is a reseller for the Chinese manufacturer for these lower cost amps. It is funny you ask that question about design as I was thinking about returns and if Nobsound is keeping records of how many are being returned and what the problem is. Thanks for watching!