[Jukebox-list] mp3 player to jukebox project UPDATE

[Aaron Heverin]

James,

I've run into that problem all the time when testing...or just goofing around with audio. You try and plug a line level input into a high impedance input - such as for a mic - and you wind up roaching the pre-amp. Of course, you can do what all 13 year olds did back in the 70s when they wanted to pump their guitar amps through their phono-in on their stereos - just turn the output of the amp down all the way, then bring it up slowly. As soon as the output of the stereo receiver starts to distort, STOP! You've hit the proper input level!

I noticed that RIAA thing all the time in doing experimentation like this. While the rest of the audio quality may sound good, as soon as you introduce bass of any kind, you get the distoration. That's why I tried the resistor box. In theory, it made sense just to drop the input levels to the amp from a line-out device rather than try to go through any impedance or power matching.

I'll tell you where we did this and it actually worked.... about 18 years ago, I was in a small pick-up band with a few friends. Since I was the one with the Realistic mixing board, I was made the "sound engineer." The problem was that the board only had two line level inputs and one tape input besides two mic inputs. Well, we had one mic that we all screamed into, but we had several keyboards, a guitar, and an effects device that all had to go into this mixing board (we got really good at overdubs). I immediatly hit on using one of the mic inputs since it was always available as an input for one of the keyboards (the guitar went through an effects device that bumped up the output to line level). Plugging the keyboard into the mic level with the output of the keyboard turned down all the way introduced TONS of hiss and some distortion. For a few songs, that seemed like a cool effect. Anyone who listened to the tracks thought their stereo was broken. But after a while, we thought that it would be even cooler to actually HEAR the keyboard and not the hiss, so I got the bright idea of building a female to male 1/4" plug adapter with various resistors tack-soldered in series with the tip of the connector to try and bring the input levels down. I finally hit on a good combination that allowed me to bring the keyboard levels up to a mid level and the mic input also to a mid level (design center). It actually sounded REALLY good!

Bottom line is that I have no idea if this would be an acceptable practice in dealing with an input to a juke amp, but as lame as it sounds, it's worked for me in testing circumstances. It's especially easy to do with the R-145 because it doesn't need a field or voice coil on a speaker to turn on. You just need unmute the relay and you're on the air. Maybe someone else can point out if this would really be a solution without causing any damage to the amp.A.