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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Upgrading the McCormack wall-wart posted by Moke on July 28, 2000 at 07:58:53:
Hi Moke,The McCormack Micro Line/Headphone Drives are Class-A units, so the heat from the casing would be caused by the high bias, rather than by excess voltage.
I agree that the voltage supplied by your new transformer should be as close as possible to that of the original wall wart, as the Micro's PS was designed with this voltage level. However, it might be hard to find a transformer that outputs EXACTLY 22V, and the closest might be one that outputs 21V instead.
Keep in mind regional / seasonal voltage variations from the mains will also affect the voltage output from your transformer by +1 or -1 volts, so some deviation can be tolerated by the Micro's PS, + or - 2 volts output. Thus a transformer that is specified to yield 21V at 110V mains input might yield about 22V if the mains go up to 115V or 120V.
The toroidal I used was rated at 22V with a 110V input. As my mains revved up to 115V at times, the output nearly reached 23V. However, the Micro Headphone Drive still worked OK for years.
I also tried a 21V toroidal transformer which posed no problems or loss in sound quality. However, if you got a 20V out/ 120V in toroid, and your mains fell to less than 110V, you might get an output of as low as 18V. In that case, the regulators may not function properly. I tried a toroid of only 14V output, and got quite a bit of noise and distortion.
Finally, I don't know if YOUR model uses 22V or not, so a simple test with a voltmeter on your wall wart should adequately confirm that!
DKB
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Follow Ups
- Voltage variations - DKB 19:25:49 07/28/00 (0)
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