cabling question

[EJG]

For years, for my son's acoustic duo act, he used a Behringher 22 track mixer into a Fender Passport 250 portable PA. It worked OK; he used the mixer because it sounded better than the Passport's built in mixer. Anyway, he used 3 ft instrument cables to connect the mixer to the Passport with no noticeable problems.

Now, he has upgraded to one of those Bose PA's. He has the Model 1 version, with the bigger base and a 4 channel mixer in the base. He was playing a show with his full electric band at a bar over the weekend, and used the Bose as the PA (just for vocals). It has plenty of power for that (the bar they were playing at likes them to keep the volume down). Anyway, they went into the mixer and then into one channel of the Bose. When using an instrument cable for that, there was a tremendously loud hissing sound from the Bose; it was unuseable. Substituting a speaker wire for the instrument cable between the mixer and Bose greatly reduced the hiss, and using patch cables instead pretty much eliminated it.

Also, the Bose expects unbalanced inputs. On our mixer, the main outs are balanced, but the sub-group outs are unbalanced. So, running from the main outs into the PA with patch cables doesn't eliminate the hiss, but running from a subgroup output into the PA with a patch cable does.

So... problem solved. But I am wondering: Why? Why did instrument cables work in the past and not now? Is there a specific type of patch cable that's recommended for this job? What is the difference between speaker cabkles, patch cables, and instrument cables? As you can tell, I know next to nothing about PA's, but I'm trying to learn.

[Rickenjangle]

Why not just use the in-built mixer on the Bose? Those things have great-sounding mic pre's in them.

[EJG]

Why not just use the in-built mixer on the Bose? Those things have great-sounding mic pre's in them.

We need more inputs than the Bose has got. At the gig, that's what we ended up doing. It meant the drummer was without a mic; not bad, but not ideal.

We need to experiment to see if it would be better to have the two main vocalists got into the Bose directly (they use SM-58's and the Bose has pre-sets for those), and the rest of the band thru the mixer into the PA, or just send all the vocals through the mixer and then into the PA. I'm thinking the former may sound better, so that's what we'll do when I'm there to help out, but the latter is easier, so that's what I'll recommend they do when I'm not around and my son has to run the PA while playing.