• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Anyone else having problems with Mercury Magnetics transformers?

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The last batch I ordered had noisy power transformers and the output sound is not up to par. I build amps and I'm seriously considering the need to replace them before they go out.

I wanted to see if it is just me or is the quality really gone that far downhill? Also, the filaments center tap can not be used as a ground in the 5e3 and these power transformers are noisy as hell. Any suggestions on a good, quiet power transformer replacement? I use another supplier, too, but was looking for other options out there.
I use Hayboer in my custom guitar amps. There is also CinTran. Both like to have bulk orders (10 or more) but might have some on the shelf if you want smaller quantities.

I am curious, how are you measuring the noise in the PT? How is it the PT is affecting the output sound? - thanks.

Have you had success with their transformers using the same design before?

Try Edcor.

In regards to the output transformers. Their open-frame transformers have a good response for guitar and you really can't beat the quality for the price. The Closed frame ones are good for Hi-Fi but are pricier.

I have yet to try their power transformers, but the company’s quality in general is good. So it may be worth a try. If they don't have what you need, contact them and they will hook you up for a reasonable price.
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No one has asked the obvious question - so I will.. Have you talked to Mercury about the problems you are having with the current batch of transformers?

I have had no dealings with these guys, but would be very surprised if they were not at least concerned and helpful in this issue - as I assume their reputation means something to them.

Talk to them first.. Post your experience here.

Good luck...
>> Talk to them first..

MM usually responds quickly to customer complaints.
Usually they'll replace the transformer if you mail it back to them.

The hard part is finding a reliable source.

Heyboer is a good choice for high quality at competitive prices.

Edcore is great for quality at a low price, although they don't make replacement parts for Fender/Marshall amps.

Sometimes I wonder if the true cause of these problems is low quality electrolytics, which may be from name brands.
Another good source is the Hammond guitar series transformers. These are a fairly new offering by Hammond.
Hammond Guitar Series

Antique Electronic has them for most Fender, Marshall and Vox Amps.

Another viable source is Lenco, They make a lot of the replacement transformers sold by MoJo Music Supply as well as other sources/vendors.

There is ALSO a guy down in Florida that has started up a smaller transformer business.
Music Power Supply

I have gotten some of his PT325's, well built, but they do have a tiny bit of mechanical hum during operation. His outputs do indeed work well but are limited to lower power amps (under 20W)

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