On December 22, 2017 at 11:05, Craig Aguiar-Winter said...
Frederick,
The cable I used was a un-shielded, un-twisted Xantech 50ft mono IR extension as I didn’t have time to go get, or make a shielded extension. This is an ongoing project so I figured I would give it a try. Aaaaaand it failed. A cable run through the halls from the two rooms to the basement would be almost 100ft in one case and about 70ft in the other. So I’m fishing the extension cable through conduit that’s behind the TVs which keeps the extension length to just over 40ft.
It sounds like you have placed the receiver such that the speaker wires have to run quite a distance, not 100ft and 70 ft, but not 15 to 30 either. Is that wise?
How about taking the receiver into the room and connecting to the speaker wires locally? If you can't do this because the wires are buried, maybe those of us who have to do such things should create a pull box or something where we can connect the receiver near the speakers for Audyssey setup.
Why?
These are CHEAP mics. We have no idea whether their response turns to crap if the wire is extended. Someone should do an Audyssey setup with the receiver near the speakers, then try various cable setups until a setup with extension cables gives the same results as without.
And we can't tell if these mics' response falls of HARD below 50 Hz (for instance) and Audyssey is set up to get less audio down there and compensate for it... meaning if we substitute another mic, we have no idea whether we're getting what Audyssey would give us.
My thoughts about using a balun over Cat6 is that I have unused cat6, run from both rooms that need tuning to a rack in the basement, which would make connection very simple. If that were to work, in projects where equipment is rack mounted else where, I could install a couple of double ended RJ45 jacks for the purpose of using a balun on the mic, or maybe even a couple of 3.5mm keystones.
Just as we don't know about the frequency response of these mics, we don't KNOW about their impedance. All we can tell is whether they're balanced or unbalanced. The rest is pure assumptions.
I have Room EQ Wizard and a good calibrated mic. I had considered going channel by channel, however I’ll be faced with extending my computer’s output down to the rack so I can hear the generated tones, which, while a much better option than this stupid mic, is still concerning me that due to the extension and any alteration to the signal that may introduce, all of the extra time spent tuning each channel separately will be for not.
This is why trying out the setup with and without an extension cable is a good idea. Sooner or later someone has to do it!
As I mentioned up top, I did make a simple mono extension using a shielded mic cable (based on an earlier suggestion - thank you). I did three tests. A new baseline with Audyssey as is, a second with the extension using just the two conductors, and a third with the same but the drain wire attached to the sleeve.
Here we go! This is what's needed.
At a quick glance I can say that it correctly (meaning same as the baseline) set all distances, levels and cross over points, however the EQ was off from the baseline. Low and mid-range frequencies were similar but my surrounds got some major adjustment above about 5k, as much as 10dB as it got to 20k, so obviously there was some major roll off in the higher frequencies. (I think – difficult to say swiping between photos).
Print out the photos. If the two methods did give such different results, we'll have to consider admitting that you can't extend the mic cable.
After revisiting the balun/keystone idea in my reply to Highfigh up top, I think I'll do another test using 50ft of cat6 and see how that compares as well.
This will be interesting to see.
Anyway like I said I will post photos of the results. Might not get to it until after Christmas though.
And thanks very much everyone for chiming in. Your input, both positive and negative is useful and appreciated.
Thanks for getting into this in this amount of needed detail!
Have to go grocery shop for Christmas. I hope you all have a safe and happy holiday.
You too!
