Historically, what's the difference between Aux and Phono?

May 5, 2016 12:30 PM

I've got a 1970s Nikko STA-5050 receiver/amp with tape, aux and phono inputs. Nowadays aux and phono seem to be used interchangeably but I know they used to be different specs.

I'd like to use them to control different inputs from modern standard 3.5mm outputs (bluetooth 3.5mm adaptor, dab radio, Raspberry pi maybe).

Can someone explain to me what the difference between the three inputs is, and if/how they can be tied to a standard modern 3.5mm output? (Other than a 3.5mm to component leads, obviously.)

posted by sodium lights the horizon to Technology (12 answers total)

They aren't interchangeable. Phono has an internal EQ, if you plug a phono into the aux jack, records sound very very trebly. Aux is a clean input. Tape is also a clean input (sometimes labeled PLAY), which also comes with a clean output (labeled REC).

Generally, you'd use something like a 3.5mm to RCA adapter or cable for this.
posted by rhizome at 12:40 PM on May 5, 2016 [7 favorites]

Phono cannot be used like Aux. Phono input expects a signal directly from a cartridge (on a tonearm). The signal that sends is a different level and has a different frequency response to "line level" signals (like you send to Aux). You can use Tape In like Aux, but not Phono.
posted by andrewcooke at 12:41 PM on May 5, 2016 [3 favorites]

Response by poster: So, are modern 3.5mm output signals aux or phono or neither?

And if they are one, can they be (with a suitable dodad) converted to the other?
posted by sodium lights the horizon at 12:46 PM on May 5, 2016

You can use the doodad that rhizome linked to to connect a 3.5mm output to Aux (or Tape In).

3.5mm outputs aren't really a standard level like Aux expects, because they're often used for headphones and have a volume control. But generally they will work OK.
posted by andrewcooke at 12:49 PM on May 5, 2016

Response by poster: Sorry - yeah, I assumed what I was calling a 3.5 to component adaptor would be needed for everything. I was more meaning "is there an electronic doodad to make the odd one out (phono) play nicely with a 3.5mm output too?"

I'm guessing no...
posted by sodium lights the horizon at 12:53 PM on May 5, 2016

They're "Aux" aka "Line" level. You can connect a phono-level device to a line-level input jack using a phono stage preamp.

("Aux" is a label you often see on input jacks, but does not refer directly to the type of signal the jack expects. It just means "Auxiliary" as in "here's where you can plug in an extra thing that isn't part of the integrated tuner/receiver/whatever")
posted by contraption at 12:55 PM on May 5, 2016 [1 favorite]

If you have to use the phono in to have enough inputs, you could apply the inverse of the equalization that the input applies to the output of the raspberry pi's output and it'll cancel out (ish). You'll lose some sound quality but the pi's audio output isn't great anyway.

The 3.5mm outs on the pi and (most likely) the Bluetooth audio adaptor are going to be equivalent to the RCA inputs on the stereo, just a different form factor.

The radio may or may not be a headphone out, which will work plugged into an RCA input but may not be ideal quality.
posted by Candleman at 12:58 PM on May 5, 2016

If you need the phono input for something besides a turntable, you can get an inverse RIAA filter.
posted by rhizome at 12:59 PM on May 5, 2016

Response by poster: Yeah, that apparent abuse of the word "aux" was what was hampering my own research.

My own reasearch (with Mefi handholding) lead me to this which looks like it's the same thing contraption is referring to.

Thank you all. :)
posted by sodium lights the horizon at 1:00 PM on May 5, 2016

Vinyl records are recorded with their audio equalized with the RIAA equalization curve.

Phono outputs are the raw audio from the record, which is "wrong" in the sense it has this pretty serious EQ curve applied to it. Phono inputs apply the reverse EQ to get back the original audio.

Per rhizome, you can get an inverse filter to do it if you want. Generally it's more hassle than it's worth to try to use phono jacks to do anything than connect to a unequalized turntable.
posted by GuyZero at 1:01 PM on May 5, 2016 [2 favorites]

In case that's not all clear, phono outputs from a turntable need to go into a phono preamp to sound correct, as others have pointed out. You can have a separate phono preamp, then that would go into any line input. The phono input on old receivers means there is a phono preamp built in there, that's why it won't sound correct if you plug something other than a turntable into it.

I don't believe there is any difference between tape and aux except that there will be both a tape in and tape out.

You can get RCA line switches to switch multiple outputs to one input pretty much anywhere and super cheap. There's probably one at the Goodwill right now. They made them for video game systems, all kinds of things. But you want a switch, you do not want a Y splitter of any kind.
posted by bongo_x at 6:39 PM on May 5, 2016

Here's an example of the switch you need, but once you know what you're looking for you won't be able to walk outside without tripping over one.
posted by bongo_x at 6:43 PM on May 5, 2016 [1 favorite]