Transformers: Auto- vs. Isolating

Thanks guys! I'd just ask if you can recommend some specific brands or sources of the transformers available in North America (or if you have any NOT recommended, also to mention them...)

BTW, doesn't a transformer makes amp 'slower'? What about those effects why people buy aftermarket PWCs?

Any type of power conditioner or treatment can make an amp sound "slower" by limiting the amount of current available to the device as it is needed. In order to avoid this, select a device that is capable of providing at least 30% - 60% more power at any given time than what the device would draw under full load. As such, if you had an amp that is capable of drawing 8 amps continuous, you would want a device that could supply at least 12 - 15 amps continuous. Since ratings from manufacturers are "fudged" so many times, the more headroom that you can provide in terms of current capacity on the "filtering device", the less likely it is to impact the "apparent speed" of the device connected to it. Too many people try to draw too hard on a steady state basis from various filters or transformers and the distortion that they produce in such cases is passed on into the audio system. By keeping the load on the transformer or filter well below capacity at any given time, those distortions and current limiting are removed from the picture or at least drastically reduced. Sean
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Sean, you mentioned vast difference in quality... Do you now anything good or bad about those offered on sites such as http://www.220-electronics.com/, etc?
On the mentioned above web site 1.5Kw transformer costs about $120, made in China. On the other side Hammond from Canada sells 1.5Kw for about $350. I guess there is something in that, how can it affect sound?

Dmitry: Those are not isolation transformers. They are voltage converters and there is a BIG difference. For one thing a "decent" 1.5KVA isolation transformer will weigh at least ( at the bare minimum ) 30 lbs by itself. I'm talking about just a transformer with no case or chassis weight added. The more "plates" in a transformer, the more it will weigh and the less likely it is to saturate under heavy loads. As a case in point, the 3.0 KVA transformers that i'm using weigh over 100 lbs apiece. This is bigger / heavier than some 5.0 KVA units that i've seen.

While there is more to finding a good isolation transformer than just sheer weight, it is a good starting point. The other major factor would be the internal capacitance rating ( a lower number is better like .00X ) and that of the rate of attenuation ( lower is better here too with -126 being better than -80 etc... ).

What are you trying to do and what country are you located in ? If outside of the USA, what voltage and frequency does your AC system run on ? Sean
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