Bob, differential amplifier can suppress even order harmonics (associated with warm sound). Voltage of each output can be seen as:
Vp=a1*Vi+a2*(Vi^2)+a3*(Vi^3)+a4*(Vi^4)+a5*(Vi^5)+ .....
Vn=a1*(-Vi)+a2*(-Vi^2)+a3*(-Vi^3)+a4*(-Vi^4)+a5*(-Vi^5)+ ....
where "a2, a4 etc" are even order coefficients. Since polarity of the input signal will be always positive (always raised to even power) for even order harmonics they appear same on each output and will be removed (assuming identical gains).
Vp-Vn=2a1*Vi+2a3*Vi^3+2a5*Vi^5....
The other problem might appear when gains are not exactly even because it can convert common mode noise/interference into normal mode signal. |
Elegal, I found more of a difference using an upgraded cable than between using XLR vs RCA connections. Using the same upgraded cable into my C2300, I preferred the XLR. As you know if you are using the phono stage on the C2300, you need to use RCA |
I think this basically sums the difference between rca and xlr and why xlr was developed. Unbalanced Cables
Standard Jack Unbalanced Cable.
Unbalanced audio cables are cables that have 2 wires that serve as conductors; 1 carries both the signal and the ground. They are less expensive, but they tend to allow the introduction of noise into the audio signal. This noise is caused by interference from the electrical fields of nearby electronic devices. For this reason, unbalanced cables should not be used for audio applications that require them to be long. The maximum suggested length for unbalanced cables is 25 to 30 feet.
Balanced Cables
Balanced audio cables have 3 wires that serve as conductors--negative, positive and ground. The positive and negative wires both carry the audio signal but with opposite polarities. This means that any noise from outside interferences (such as from other electrical devices) will be cancelled out. Balanced cables are suitable for audio applications that require long lengths (more than 25 to 30 feet).
XLR Cables
XLR Female Connectors
XLR cables are balanced cables. They have circular connectors with 3 pins--positive, negative and ground. Essentially, they are the same as a TRS cable (which stands for Tip Ring Sleeve). The only difference is the type of connector (TRS cables look like standard-jack cables). "Pin 1" (the pin on the left side when facing the male-connector, or the hole on the right side when facing the female connector) is always the ground signal.
How XLR Cables Work
When two balanced devices are connected, the XLR cable delivers a positive audio signal, a negative audio signal and a ground signal. The positive audio signal and the negative audio signal are identical, except that they are inverted. If electrical interference is encountered (such as from nearby electronic devices), that noise enters both the positive audio signal and the negative audio signal. When the positive and negative signals reach the balanced device at the end of the chain, one of the two audio signals is inverted. Now the two audio signals are identical in every way. However, the noise that was on the audio signal has now been inverted. When the inverted noise is combined with the original noise, they cancel each other out. All that is left is the original audio signal. I compared the 2 side by side when I had a Meridian G08 to an Octave V70se. What I found was the xlr was louder as it should be since the average voltage output is typically 4V where the rca is typically 2V. For that reason I decided on the rca because I didn't care for the higher gain. Others prefer the higher gain. I'm glad I decided on the rca because when I replaced the Meridian with a Naim music server it only has rca connectors. On the other hand if I needed cables that are 20ft or longer I would highly reconsider the xlr and equipment that has a truly balanced designed. Just my opinion |
I'm mystified that RCA and phone plugs are still around, but I have to accept it and use them daily...there may be an argument for RCAs taking up less space, but after many years of using XLR mic and balanced ins and outs of live sound mixers and recording stuff I'm an athletic supporter of XLRs, even when not part of a balanced system. When I'm declared Ruler of the Universe I'll demand Neutrik Speakon connectors and XLR plugs be universally used all the time. Besides, Neutrik Speakons are made in Liechtenstein, which should be all you need to know. |
02-23-14: Wolf_garcia writes: Besides, Neutrik Speakons are made in Liechtenstein, which should be all you need to know. I've done a lot of IT consulting in Liechtenstein and you are right. Workers there inherit holidays for both Switzerland and Austria and average 14 public holidays a year, and in addition, typically with the whole of August off. A good life - and it's a very pretty place; but you really want to stay in Feldkirch, just across the border in Austria. Regards, |
