Wright Sound WPL-20

[dvb]

Back in March/ April 2012 there was discussion about issues with this piece.  How did you all make out?

I'm very attached to my WPL-20, but it does have a noisy power supply.  That it, a hum from the power supply unit itself, not through the speakers.
Any tips from anyone familiar with George's products would be greatly appreciated!

(Mine has the separate power supply, with a 6x4 rectifier.  Seems to the be the second unit made, and by George himself, back in August 2001.)

[Doc B.]

I would suggest contacting Roger Hug, as he volunteered to service George's products. Unfortunately George never built very many products the same way twice, and never produced schematics for his commercial products (I and several others went through his whole house looking for them after he passed away). So in the end you may have to pay a little more than his very reasonable prices to have someone who understands electronics sort out any issues.

[Paul Joppa]

... a hum from the power supply unit itself, not through the speakers. ...

Doc B's suggestion of Roger is worthwhile - Roger is extremely capable. If there is a circuit problem causing this, he will be able to find it and fix it.

Assuming no circuit problem, the noise seems most likely to be a power transformer vibration. There are two approaches - replace the transformer with a more robust unit, or work on silencing the unit you have.

If you have a part number (it may be a Hammond?) I can comment a little more on options. A photo might show whether there's room for a larger transformer.

Otherwise, tighten the screws holding the transformer together, if they are loose - they don't have to be super-tight, but loose is a problem. Tighten the mounting screws. If the transformer is not isolated (a photo would help here, too) there may be some other useful things to do.

My two cents.

[Chris]

When I start my projects here, I was thinking of placing an O ring , or some kind of hard rubber under the trannie and then add a locking nut to prevent loosening... Would something like this be beneficial or just plain unnecessary?

[Paul Joppa]

All our power transformers run at a conservative magnetic field strength, which greatly reduces the chance of vibration.

We also habitually use insulating fiber washers to mount them. Those could be replaced with some sort of vibration isolation. It's tricky - you can't just use one rubber washer because the machine screw will still connect the transformer to the chassis. You need one on each side of the chassis or the mounting lug. And if you compress the rubber very much, it gets stiff and provides less isolation. To work well at 60Hz, a suspension must be surprisingly floppy.

[Chris]

Right, makes sense.. Thanks  Paul

[dvb]

Thank you very much for all the replies - sorry to be so late in acknowledging them.

I have been in touch with Roger, and also with Jim Hammond of Applied Fidelity.  Jim has re-built a WPL-20 the the satisfaction of a fellow on Audio Asylum.

Jim has offered to build me new power supply, based on George's circuit for his AG Signature phono section.  It has a large toroidal transformer, which may be over-kill, but I'm ready to take extreme measures!

Here's a link to an AA thread showing rebuilds of stock power supply and of the AG Signature power supply:

newbielink:http://www.audioasylum.com/cgi/t.mpl?f=tubediy&m=190913 [nonactive]