We were lucky enough to have Tristan Miller of Catherine North Audio over for the day to give Quad Twisted Pair an examination. Tristan is an Electronics Technician with a comprehensive background in Electrical systems being a licensed Electrician. Having implemented over a thousand channels of QuadTwisted Pair in his recording studio(s), he has been a great influence of the ideas surrounding implementation and execution. His understanding of Electrical and audio systems is like no other. He came armed with a brand new 1000 foot box of CAT5e Quad Twisted Pair cable to play with. Along with repeating our original tests, some new tests were conducted to compliment our original findings.
We let Tristan drive the Audio Precision 2700 so all tests results were independently confirmed:
Here we are looking at the Distortion and Phase response of the cable. The phase response is relative to another pair on the same 1000 foot QTP cable. This test confirmed that there is indeed no “Sound” to Quad Twisted Pair wire.
Tristant suggested comparing the 100 feet of Quad Twisted Pair to a 1000 foot microphone cable he wished he brought (seriously this guy has everything) Lucky for us, 300M of Delco AES cable was kicking around the Ward-Beck Systems test department and we used it to compare the frequency response to 1000 feet of Quad Twisted Pair:
There is simply no difference in performance when properly terminated differential transmitters and receivers are used:
We also measured cross talk of QTP. The crosstalk was measured with a 30dBu tone and resulted in greater than 100dB of channel separation:
“If you’re going to measure Analog audio you need an analog scope”
This test will be talked about later… It involves a 600V power transformer