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phono vs line inputs on stereo

My apologies if this isn't the proper sci.electronics group for this question --

I have an old one-piece stereo, the kind that's designed to look like a rack system but isn't. It has just one set of RCA inputs, which are intended for a phonograph. It's my understanding that the phono inputs expect a much lower-amplitude signal than a regular set of inputs would. I'd like to use this stereo, though, for my VCR, DVD, Nintendo, etc.. I've done a little searching, and seen a suggestion to go inside and short out the phono pre-amp, as well as a couple simple circuit designs[1] to un-amp the line to get it ready for the phono's pre-amp.

Now, I'm a physicist, so I should probably be able to do either of those, but my only electronics class was way back in 1996, and I didn't enjoy it very much. If there's a cheap little device I can buy that will fix this up for me, I'd prefer that. I see that there are separate phono pre-amps available to allow a phono to go into a line input, but I don't know if the reverse is possible. Or even if I can just hook up a device like that backwards and have it work. A non-powered device would be highly preferred, naturally.

Anybody have a suggestion?

[1]
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--Steve-o

--
Steve Stonebraker |     http://www.physics.ohio-state.edu/~sstoneb/
sstoneb@yahoo.com | Transformers, astrophysics, comics, games, cartoons.
Reply to
Steve-o Stonebraker
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Sounds like two resistors should take care of it (called a voltage divider or a pad).

Reply to
Charles Schuler

Because phono inputs are RIAA-equalized, they also need to be bypassed, so in addition to resistors (and probably coupling/DC blocking capacitors) we need to bridge around the RIAA EQ.

--
John Miller
Email address: domain, n4vu.com; username, jsm

When the going gets tough, the tough go grab a beer.
Reply to
John Miller

I am not certain about this, but I think that phono inputs generally have a tailored frequency response, not a flat one as a standard input would, so your sound might be a little weird even with level correction...

RIAA equalization rings a bell, try searching Google for more info.

I have found a reverser for RIAA, try this - it seems to be what you need:

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Cheers, Rick.

Reply to
Captain Rick

Is it matched for magnetic or ceramic cartridges? How old is it?

Tom

Reply to
Tom MacIntyre

Yeah, that bears some similarity to the design I found. I can try to build something myself, I guess. Maybe I can bug the guys in the department electronics shop to make a nice little boxed device for me. :)

Thanks for the suggestions, everyone.

--Steve-o

--
Steve Stonebraker |     http://www.physics.ohio-state.edu/~sstoneb/
sstoneb@yahoo.com | Transformers, astrophysics, comics, games, cartoons.
Reply to
Steve-o Stonebraker

Not "gerally": always.

It will sound _dreadful_, I'm sure.

You're onto a loser with this one. It's really not worth it, IMO.

Noise will be pretty bad, I'm sure.

Martin

--
M.A.Poyser                                                  Tel.: 07967 110890
Manchester, U.K.                                http://www.fleetie.demon.co.uk
Reply to
Fleetie

"Fleetie" wrote

"generally", even.

Reply to
Fleetie

--Steve-o

If you look at the URL he gave above, you will see that there needs to be equalization. If you use just "two resistors", then you will get terrible sounding audio.

Reply to
Watson A.Name "Watt Sun - the

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