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In Reply to: RE: I would worry about the transformer on a rubber pad. posted by Norm on April 16, 2012 at 20:15:53
energy can not be created or destroyed: all one can do is to transform that energy. The application of AC on a power transformer has what they call a magnetostriction effect on the transformer core. The hum is is unfortunately part and parcel of using a transformer.
Personally, I find that transferring that energy to a chassis which contains your actual electronics is worse than isolating the hum where it is generated. That's probably one reason why separate power supplies often sound "better": the hum from the transformer is isolated from the actual electronic circuit.
Even with EI core transformers, a routine mod for me is to mount the transformer on rubber grommets. That additional isolation adds a degree of warmth to the component and gives a noticeable increase in midrange detail. This applies not only to tube gear, but also to solid state fully transistorized gear, too. Of course, there are alternate means of warming up a circuit design, and isolation of the transformer may accentuate the issue, so be aware.
YMMV, obviously...
Stu
Follow Ups:
I asked if he had ever used StillPoints isolators under large isolation transformers. He had and said it made a big difference. The StillPoints convert vertical vibration vectors into horizontal ones which can go nowhere and thus into heat.
use various footers under isolation transformer, however, my issue was using them under transformers in an electronic component chassis. My apologies if I didn't make myself clear about that.
In an electronic component with active circuit, motion is not very good. With tube gear, that would be rather obvious, but few realize even solid state gear sounds better if vibration is kept away from the circuitry.
Very early on, when Sorbothane first came out, I remember applying small bits, about a 1/16 inch square, to the tops of the TO-92 transistors in a PS IV preamp. The change in sound was dramatic: the characteristic "bright" PS sound became very warm and rich, and yet the PS had an external power supply housing the transformer.
Pondering over why this would be so lead me to dissecting transistors, and it was an education to do so. TO-3 types have tiny little wires jumping the leads to the actual transistor element, roughly a 1/4 inch square, and it is set in a hollow space, although early types are curiously fluid filled (heat transfer?). The fact that you have tiny wires attached to a basically a pure silicon element sort of makes every transistor a modified crystal oscillator to a certain extent.
Again, I would reiterate and say that it is best to keep any source of vibration as close to the source as possible. Diffusing the energy into other components is generally not beneficial for good sound, as that energy is changed in frequency and amplitude, but still present. If you are extremely careful, it is possible to transmute that energy into something outside of the audible bandwidth where it may be relatively benign, which seems to be the goal of most designers. Otherwise, you get an accentuation of the resonant frequency of the device in question.
Again, YMMV.
Stu
How difficult is it to re-thread a 1/2" portion of a nylon threaded rod? I'd like to go from an 8mm diameter rod down to a 6mm diameter rod for 1/2" and what would I need tool-wise? Should be fairly easy I would think as nylon is pretty soft.
Is a regular tool die would work fine. Sears, and other hardware stores sell them, Being that tools are often made in China these days, costs have been getting progressively cheaper. (Check out Harbor Freight). I buy Sears Craftsman tools because of the lifetime guarantee and because IIRC I paid about $100 for a complete set of taps and dies ( metric and English thread). The dies are available separately, BTW.
Incidentally, as long as you're not moving the component around much, I have simply used RTV silicone caulking compound to glue down the transformer. Just be sure to remember to replace the original bolt when shipping the component.
Stu
I too usually buy Sears Craftsmen tools, in large part because of the warranty and because of the close proximity to my home. Its nice to know that they (the dies) can be purchsed separately. Would I need to reduce in 1mm steps or can I go directly from 8mm to 6mm without creating a problem? Sears tool department does seem to be getting smaller as of late, and though Harbor Freight is a 30 minute drive I might end up there because of the decreased cost in purchasing the dies I need.
Many cautions have been given about shipping or moving the amps without the steel hold-down bolts being substituted back in, and as heavy as the transformers are, I can certainly understand why, as they could easily break loose. Caution noted and thanks again for your help.
I would take a bastard file and simply file off the thread for the larger diameter. That'll get you pretty close to the finished diameter.
Stu
You hear that manufacturers? We want miniature roller-block assemblies to put under our transformers. No joke.
Actually Norm, something like this already exists in the automotive industry. There is a bearing plate that goes between the top of a suspension strut (shock absorber) in your car and the underside of the shock tower of your car. These two plates have a race with small ball bearings in it. The purpose is to keep the suspension from binding when you turn the steering wheel, most importantly when the car is sitting still and you are turning the steering wheel, as in a parking lot. Forgive the simplified explaination for those of you in the know. Now all we have to do is try it. The size of the bearing plate might even be close to the size of my toroidals. I was in the shop when they replaced the front sruts on my daughters Honda Civic and saw them fall apart (178,000 miles) bearings everywhere, but new bearing plates might well be the trick, or something like them. Thanks Norm
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