Plugging computer output into stereo problem

A phono input is also equalised to the RIAA curve used by records. This will cut the treble and boost the bass from your computer signal.

Don't plug it into the phono input.

Very true, but assuming that you can live with that / correct it enough with the computer's graphic eq control panel, then you will need two resistors for each channel, one in series and then one to ground to form a potential divider. I would suggest initially trying about 10 : 1 so suitable values might be 47k ohms in series with the 'live' leg of the feed, and then 4.7k ohms from the 'amplifier' side of that new resistor, to the 'ground' leg of the feed.

Arfa

Right, and where should I plug it? I said there is no AUX and no other inputs. The tape deck is built in, so no tape inputs either. The phono is the ONLY input.

I'll try the resistors as posted.

I was also wondering what would happen if I put an equalizer in between? Suppose all I can do it try it. I have a small 6 band one that I'm not using. I guess that could compensate for the RIAA too. Although I really find the bass and treble pretty much ok. Besides using the bass and treble controls on the receiver, I can fine tune the sound in Winamp.

Thanks

Try this...

Hi!

Well, if you don't have an AUX connector, how about one for TAPE?

That should work properly with no modification required.

William

Hi!

Oh. I guess the suggestion I just made won't work very well! :-)

If the phono input shouldn't work, I see two other possibilities--a cassette "shell" adapter with a stereo miniplug or even a low power FM modulator, such as the kind that are sold for portable CD players, iPods and such.

William

I dont know if you can find it, but there is a small gadget, that goes into a tapedeck, and feeds the signal to the tapereader head. A friend of me uses it often.

Normally sold for car use. When cars had tape decks.

Assuming there is an FM tuner in the stereo, there are inexpensive RF transmitters in stores for playing iPuds thru car radios or other systems.

I found one a while ago for maybe $3 at a discount place, but don't know how it actually sounds, as I haven't tried using it.

-- Cheers, WB .............

That assumption about being able to correct it adequately with the computer's EQ may be a bit of a stretch... there are likely to be some significant frequency errors.

The OP might want to try building a simple "inverse RIAA" equalization circuit, which would also act as an attenuator. By inserting this between the incoming signal and the PHONO input jack, it would cancel out the PHONO input circuit's relatively high gain, and also reduce the signal level enough to avoid overdriving. These really aren't all that much more complex than just a two-resistor voltage divider... only three more components are needed.

Take a look at the following document:

The circuits aren't complex. The oldest version (by Reg Williamson) requires three resistors and two capacitors, per channel. I'd guess that you can probably buy acceptably-close-to-the-right-value parts at Radio Shack even today... if not, Mouser or Digi-Key will certainly have them. Any electronics hobbyist you know, can probably find acceptable parts in his/her junk box. The whole circuit could be haywired together into the middle of a "quarter-inch stereo miniplug, to two RCA plugs" jumper cable (again, even Radio Shack has these), insulated with tape or heat-shrink tubing or "liquid electrical tape", and you'd be good to

On 6/9/2010 6:31 AM William R. Walsh spake thus:

Apparently you missed the part where the OP said "I said there is no AUX and no other inputs."

Here's another suggestion to the OP: since you're contemplating doing a little project where you have to solder up stuff, why not just tap directly into the stereo's line-level input? Wouldn't be difficult at all: just locate the volume control (undoubtedly a 2-gang potentiometer), and wire a connector for the computer input across the ground and high sides of each pot. Should work fine.

Hi!

I did, to wit:

William

From my experience, the tape head things sound really bad - no highs. It probably depends on how well the heads align, but I would rather listen to unequalized RIAA than the particular tape head thing I had.

Another option is to open the stereo, find the phono preamp, and bypass it. In other words, connect the wires that go from the selector switch to the output of the phono preamp directly to the phono input connectors.

They vary quite a bit -- I've got a cheapie Goodmans one that's awful, and a Sony one that works very well. I don't think I'd want to use one on something other than a car stereo, though; even if the sound quality's OK, you're going to have the cassette deck's motor running all the time.

That'd be my preference, if the OP's reasonably comfortable with electronics or can find somebody else who is. A few minutes' careful poking around will probably find a couple of tracks that can be cut to inject line-level audio at the output of the preamp; you could even add a switch if you want to retain the phono input. But I'd imagine the OP will be quite happy just using an attenuator and fiddling the tone controls...

Another easy place to find is the top of the volume control, add a changeover switch and series caps -- drawback is that you likely lose the tone controls.

Grant.

Yes, that was my contention. Everything that has been said about reverse RIAA compensation etc is absolutely true, and yes, such a network is reasonably easy to knock up, but I got the impression that, given that you know that what you are doing is not ideal in the first place, but the *only* way that you can do it, then it is just a QAD 'fix' that you are looking for, and the simple two resistor potential divider network will do that just fine. I am also sure that between the Winamp G.E. and the tone controls on the stereo, you will be able to compensate adequately (but not perfectly) for the non-linear frequency characteristic of your phono input.

Arfa

It will sound like crap in the phono input even if you get the level down to a few milivolts by padding the output of the PC. You didn't mention if this old stereo rig had an fm tuner in it but if it did what I would do is build a small fm transmitter from a few spare parts and broadcast the pc on an unused channel. You can also buy those things to play an Ipod or mp3 player on your auto's stereo.

Given that it will be highly compressed and messed-about-with MP3s played via Winamp, the additional tonal distortion introduced by flinging the signal into an RIAA equalised phono input, will be the least of the OP's problems ... :-)

Arfa