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I have a fostex mr-8

DC in just says 12V -- what kind of AC adapter do I need?

If I use the wrong kind of adapter will I jack the thing up?

I've tried looking online - but I'm kind of worried about making a wrong purchase and ruining my device.

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closed as off-topic by Ben Miller, Meaningful Username, Dom, Shevliaskovic, nonpop May 4 '14 at 7:30

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Have you tried googling "Fostex mr-8 manual"? –  Meaningful Username May 2 '14 at 11:17
This question appears to be off-topic because it is about audio production equipment. –  Ben Miller May 2 '14 at 17:42
I could be wrong, but my understanding is that DC-powered devices have some amount of tolerance for non-optimal voltages (my XO-1 laptop would even accept the wrong polarity), but the thing that may damage it is insufficient amperage. Of course the snafu is that they usually tell you optimum voltage upfront, but you have to dig through the manual to discover the amp needs. –  luser droog May 3 '14 at 5:30

3 Answers 3

up vote 3 down vote accepted

Don't know where in the world you are, but obviously the AC has to match your socket in the house.Could be 220v. The 12v-- means 12 volt DC - some equipment takes 12v AC, but a straight line means DC. The next problem is polarity, as DC can be only made to work one way , as in positive tip or negative tip.The wrong way will possibly not affect the machine, but it won't work.It's not worth just trying it blind though.It tells you on the machine. Next is the size of the DC plug.Probably the same size as Boss equipment, but a lot of that is 9vDC, so it won't help.The proper adapter is AD-12A. Try Fostex themselves, or ebay.-Got by googling 'fostex mr-8 manual' !!

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I'm under the impression that trying to use the wrong polarity can damage some equipment; I've heard this in the context of guitar effects pedals, where some models do not have reverse-polarity protection components in their circuits. So I'm suspicious that assuming "The wrong way will probably not affect the machine" is dangerous to the recorder. –  Dave May 2 '14 at 15:17
Thanks for a good suggestion, but it would be hoped that anyone in their right mind wouldn't plug in willy-nilly. Or would they? I've edited accordingly. –  Tim May 2 '14 at 15:34

While the above answers are useful, no one mentioned the current or wattage needed. The manual only tells you 12 vdc, and if you look close enough to the manual pictures you can see it has a positive tip on the connector. Further searching, I got this.



Power supply is called Model AD-12A from Fostex. Input: 120V 60Hz 12W Output: DC 12V 600mA

Power jack is + to pin and - to body. Approximately .218 inches in diameter with .072 socket for pin

To substitute the Fostex version you need to find:

1) an adapter that has the same connector type

2) one that is wired with a positive tip

3) one that is 12 volts DC

4) and one that can deliver 600 mA or .6 amps roughly 7 something watts, but they recommend 12 watts, so to be absolutely above bar here, 1 amp would be ideal.

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+1 for mentioning amps. Radio shack always sends me away when I don't know this (1 amp for small devices is usually enough, but the consequence of insufficient amps in the power supply is possible damage to the device (so they tell me), so being armed with the info "1 amp" should be enough to buy a generic adapter. If you take the device with you to the store, they can match the connector type (tip) too. –  luser droog May 3 '14 at 5:23
thank you for keeping me CURRENT :> –  filzilla May 6 '14 at 21:43

Apart the voltage, the power (should be enough) and polarity also matter while too weak adapter usually fails itself rather than damaging the device.

A relatively safe work around seems to use rechargeable batteries instead.

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