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Old 29th December 2011, 02:19 PM   #1
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Default Mengyue mini el34b

Hi, new to valve amps and not sure if anyone can help this this issue. I purchased a meng mini el34bed (24w) amp via eBay and after switch on,have noticed an audible hum/ buzz from one of the transformers, I think it's the mains trannythat sits at the front of the unit and there are two at rear, which I assume are the output transformers, these are ok. After much complaining to seller in hong kong, they sent out a replacement and guess what, that has same issue?
After suggesting to seller it was a design issue, he quoted that it could indeed be that due to price of amp, about£110 in uk. The hum is definitely from the transformer and not speakers, I have checked inside the 1st amp for dry joints loose connections etc but have not found anything obvious.
Does anyone have any suggestions on how to isolate the noise? I can mail pics of amp and internals if this would help,
Many thanks,
Tom
(Wales/Uk)
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Old 29th December 2011, 02:29 PM   #2
SY is offline SY  United States
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That hum/buzz is because of the transformers (probably magnetostriction), not anything simple like a bad solder joint. The only way to fix it is to put in good quality transformers with nice, tight laminations. At least the seller was honest with you that the problem was the cheap parts!

You could try tightening the screws that hold the transformer together and hold it to the chassis, but I wouldn't expect much improvement.
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Old 29th December 2011, 05:35 PM   #3
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hi,thanks sy for the speedy reply, I was hoping it would have been an easy fix, but the cost of a new transformer would outweigh the cost of a new item!!!
Its strange, but I have a friend who has bought these with no problems,albeit different specs,valves etc, but at the same price level, with absolutely no problems at all and yet ive had 2 with the same problem? Maybe its just an issue with this model layout?

thanks again,
tom.
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