So I hope some of the question is asked in the title. Functionally, would an aux in would do the same as a preamp in on a regular amp?
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Well, I have no idea what happened there. The title got fucken murked. I'll continue it here: "...Preamp In?"
..I was watching my death.
Last edited by timbit2006 at Jan 10, 2017,
timbit2006 No. Aux Ins are usually for 1/8 inch (3.5mm) lines like from a computer, Iphone, etc audio output. Typically it is for playing music through the amp, alongside the guitar input. Their differences has something to do with something something impedance something something line levels something something...
I actually checked out the schematic of a Roland Cube 60 and it pretty well is just a power amp in. I have no idea why I mixed the terms preamp in and power amp in in my original post. I only looked at the schematic real quick for about a minute but it looked like the "Main in" which is the aux goes directly to the volume pot.
At the end of the day, the lesson learned is a Mesa Boogie Triaxis Preamp doesn't really sound good through a Cube 60's power amp and speaker.
..I was watching my death.
Quote by timbit2006
So I hope some of the question is asked in the title. Functionally, would an aux in would do the same as a preamp in on a regular amp?
"Aux input", is sort of a euphemism for "Line input". In home entertainment equipment the "Aux in", would be for a cassette deck or similar.

It's pretty much the same in guitar amps, save for the difference in connector types.

The inputs for guitar pickups have can extra stage of amplification, (a preamp), before they hit "line level", or auxilliary input level.

However both the line in, guitar in, or magnetic turntable cartridge input, (remember them?), happen before the volume and tone stages of the power amp.

Now "Line output" is different. That is still at "line level". However it is tapped before the tone and volume stages so the the signal it is feeding is "flat" or identical to the source. This output would be for something such as the line input of a cassette deck. It's so you can't tamper with the signal level or EQ, on the way to the recorder.

"Pre-Main split" are also different. A situation where you would use that is perhaps from a mixer (with EQ), directly to a power amp only.

(Some receivers for home use allowed you to split the preamp (tone and volume stages) off, and drive a separate preamp into the power amp stage. (It doesn't have to make a whole hell of a lot of sense or even get used, it just used to get sold as a feature).
Last edited by Captaincranky at Jan 11, 2017,
Well, I'm honestly not sure how to respond to that. I entirely murked my original post and I honestly accidently pressed something on my keyboard to make it auto-post before I corrected myself. That's actually a really good explanation of line level.
The original question should read, "Is an aux in functionally the same as a power amp in?" Which in the case of the Cube 60 it seems to be so according to the schematic. I guess to explain: My friend bought a Mesa Triaxis preamp and had it plugged into the input of his cube, so I started thinking about the aux in and how it probably sounds better bypassing the world renowned Cube preamp. Of course it apparently sounds like shit even through the Aux in so he's just going to have to wait until jam to try it out.

On the last bit of your post though, when you say split the preamp, are you meaning the tape ins/outs? From what I understand the tape out=preamp out and tape in=power amp in. On some of my hi-fi amps it's post-volume and others it's pre. My Yamaha Natural Sound CA610A has the tone defeat, but I can't recall if my model has the volume defeat; I know the later version does. Now that I think about it, I was actually using a Sansui receiver as a phono preamp for a modern 5.1 amp for quite a while until I upgraded to a Technics unit.
..I was watching my death.
timbit2006 For the most part, aux-in lines are meant to be just an input for the signal to be amplified cleanly to be sent to the speaker. So routing it to the power amp, where there is the least amount of coloration at a point before the signals are elevated high enough to drive a loud speaker, is ideal. However there are still impedance issues between what a preamplifier might output and what the aux input is expecting.

There may also be signal level differences entirely- the preamp might output line level +4, but the aux in may be expecting -10, etc. Audio levels and inputs are my weak point so I am sure so I am missing something- but the take away is that you cannot just plug any output into any input that fits. Also if the preamp has any cabinet simulation on it, that will go against the Cube's speaker response and make it sound bad- two speaker sims on top of each other.

Will Lane covered it. i just wanted to note that you can get conversion jacks from both 1/8>1/4 or 1/4>1/8 for a buck or two if needed.
the aux input accepts a line level signal (calibrated, 95% of the time or so, for -10dBV).
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