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Pair of Hammond 710 HV Tube Plate Power Transformers

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Hammond Transformers **Sold** to member JR_W...Thanks!

I have a pair of Hammond 710 High Voltage Plate transformers for building tube amplifiers. I was planning on building a pair of either EL34/KT88 mono-blocs or 300B mono-blocs with these transformers. I've had them for about 7 years and haven't built anything with them yet so it's time to let them go.

It looks like they may have been used for proto-typing something in the past since the leads have been cut, but there's still plenty of lead left for an amp build.

These units had an unsightly amount of varnish on the end bells and laminates from the factory with an assortment of blobs and bumps of said material over their exterior. Some of it has started to flake off. I would suggest a light sanding on the end bells only (I've read that one should avoid sanding the lamination stack) and a coat or two of hammertone paint. A solvent might remove the varnish as well. I didn't try anything but perhaps some acetone or xylene (to be used in a well ventilated area to preserve brain cells ;>) would do the trick.

Their dimensions suggest they're the 710 units although using line AC input, I got 424-0-424 on their outputs. They're rated at 375-0-375 at 115volts so given their regulation and the fact that the line at my residence is above 120volt it's apparent they are the 710 vs the 710A units as listed here: Hammond Mfg. - "Classic" Power Transformer - (700 Series)

Some amp designers claim that decoupling the filament windings from the HV B+ windings by using a separate transformer has considerable sonic benefits. I was going to determine that myself with a build using these units, but alas I'll have to take someone's word for it.

In addition to selling them outright, I would consider trading for a DAC I might find interesting (with a USB input preferred) or perhaps some 6.5" coaxial drivers for a home audio project I've been contemplating.

Angela Instruments wants $74.00 each plus shipping: http://www.angela.com/hammondenclosedplatetransformer710.aspx These are available at $85.00 for the PAIR shipped to the CONUS. Shipping will be via USPS medium flat rate and is only available within the CONUS.

Of course local pickup is available in Glendale, AZ (or Anthem, AZ)


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