Audio Problem

[Мастер]

So here is the situation:

a) Old turntable, with an audio output that has separate little round jack thingies, in red and white

b) Old stereo system, but not so old that it actually has a turntable, has nothing but an "aux" input from other devices

c) Plugging the turntable output into the "aux" input on the stereo system actually works, but even with the volume turned up to the maximum, I can't make the windows rattle - it is still barely audible.

Any suggestions?

[Lance]

You either need a pre amp, or a turntable that has one built in.

[Мастер]

Thanks for the information, I will procure one of these wonderous devices straight away.

So is it correct to say, in the pre-digital days, the difference between inputs labelled "phono" and "aux" is simply one of level, the two being otherwise basically the same signal format?

[Lance]

Yes, exactly. All "line audio" signals should be the same levels regardless of device. The one exception to that is the magnetic phono cartridge. Even ceramic cartridges were high level, but magnetic cartridges need a pre-amp. Some receivers used to have a MAG/CER switch for that very reason. In MAG, they would switch in an internal pre-amp.

[Enzo]

Aux, Tuner, Tape, CAssette, VCR, DVD, and most anything else you can think of that might have an audio input on a stereo system are all what we call "line level" signals.

"Phono" is not only a much lower level signal requiring extra amplification - or "gain" - but the phono inputs also have what is called an RIAA equalization curve. All that means is to compensate for the recording process to records, the phono preamp has a very exagerated bass response and a very low treble response.

You might notice that playing a turntable through an AUX input yields not only low level, but also a very tinny sound. That is because the AUX input lacks the RIAA emphasis on lows.

The preamp Lance linked is exactly that, an RIAA phono preamp, and it connects between the turntable and the AUX input of the stereo system.

Usually a turntable has an extra small ground wire. That should be connected to the case of the phono preamp to reduce hum. Usually there is a screw for it.

Ceramic cartridges are the cheaper alternative and have a much higher output level than the better magnetic cartridges. You can usually plug ceramic cartridge tirntable outputs into like level inputs.

If you care:
The groove on the record wiggles around in direct analoque to the audio signal waveform. If it was simply recorded, the bass notes would move the groove way over from side to side and there would be little room on the record for lengthy tunes. SO they purposely record onto vinyl with the bass turned way down and the treble way up so the groove efficiently fits on the platter. The playback amplifier has exactly the opposite frequency emphasis to exactly counteract the recording process. So the net result is full range audio. It isn't just as simple as turning a couople tone controls, but one could make it halfway listenable by doing so.

RIAA - recording industries assoc. of AMerica - or something like that - established the standard and it is a four pole equation. So there are lots of little resistors and capacitors to get it just right.

[Мастер]

You might notice that playing a turntable through an AUX input yields not only low level, but also a very tinny sound.

I did notice that, in fact, I even checked the speaker wires to make sure they were connected solidly (this system has four wires to each speaker) :P

Usually a turntable has an extra small ground wire. That should be connected to the case of the phono preamp to reduce hum. Usually there is a screw for it.

I've got it connected to the main system cabinet now.

Ceramic cartridges are the cheaper alternative and have a much higher output level than the better magnetic cartridges. You can usually plug ceramic cartridge tirntable outputs into like level inputs.

OK, this solves the level then, but we still have the problem with the bass/treble not being right, correct?

Enzo, many thanks for your very thorough and helpful answer. The "user-friendliness" of some systems (plug phono into phono, don't worry about how it works) have kept me from understanding what is really going on, this is very helpful.

[Lance]

OK, this solves the level then, but we still have the problem with the bass/treble not being right, correct?

You shouldn't. The pre-amp should resolve that as well.


Enzo;

I never knew that about the response curve or why. I always thought it was just the level that was much lower. Thanks for teaching class today.

[umop ap!sdn]

Yeah thanks Enzo, that's really neat. I have a related question...

The groove on the record wiggles around in direct analoque to the audio signal waveform. If it was simply recorded, the bass notes would move the groove way over from side to side and there would be little room on the record for lengthy tunes.

The groove goes side to side? I was told that it goes up and down (as in the depth changes). Which gave me reason to wonder why the needle doesn't simply plow right through the vinyl.

[Lance]

Here are a couple of interesting links on the subject.

The second one addresses the groove graphically, and quite nicely.

Great Sounding Records

Stereo disc recording

[umop ap!sdn]

Interesting, thanks!

[Enzo]

I'm with Lance, use the preamp and a nice quality magnetic cartridge. Ceramic carts will eliminate most of the need for preamps, but they will be harder on your recrods and will not have as nice a sound. Ceramic cartridges are the ones they use in little kiddie record players and cheap stereos. A reasonable quality phono cart can be had from Audio technica for $30 and up. You can still spend several $hundred. AUdio Technica is a good choice because the company is alive and well and replacement styli (needles) should remain available for a while. SOmetimes styli can be hard enough to find for a particular cartridge that it is more expedient to replace the whole thing than just the needle. A-T makes a lot of professional audio stuff like wireless microphones, recording microphones, sound procesing gear, and even DJ equipment.

Yes, that graphic presentation shows it very well. SOmehow all that motion looks sorta pornographic.

[Мастер]

Thanks for the information, I will procure one of these wondrous devices straight away.

OK, so maybe not straight away. But I have one now, it is connected, and I have a record playing, probably for the first time since the 1980s :P Mozart's Symphony #40. There's a bit of static, but it is still pleasant to listen to. The record is frightfully asymmetric :( Not sure if the static is because of the phonograph, the cartridge, or the record, or something downstream. I'm thinking probably the record, because it sounds better now than it did a few minutes ago. Had to connect it to the "CD" input on the amplifier system (brand new), since it doesn't have a phono input. Not a problem at present, because there is no CD player here - my old one doesn't work anymore, so if I want to play a CD, I can play it in Car the Younger, or pop it in the DVD player. But if I get a CD player for this system, I'll have to reallocate the phono input somehow...

It's supposed to be a universal remote, but dammit, I can't get this 1980s phonograph to do anything with it...

[KLA2]

Yes, that graphic presentation shows it very well. SOmehow all that motion looks sorta pornographic.

it does. Since you mention it.

Must-go-now-and-wash-brain ...