Issues with microphone cables

Question

I'm new to sound design but I noticed something odd with a set of cables I purchased. I have a set of 3' Xlr cables that I purchased along with a set of Xlr(Female) to 1/4"(Male) adapters. I am noticing that when I have everything hooked up to my mini mixer it does not sound as good as when the microphone is hooked up with a 20' Xlr to 1/4 in cable. Everything seems lower and the sound isn't as deep as it is with the Xlr to 1/4 cable. I know that my mixer does not have a preamp but I'm not entirely sure that's the problem. Are my Xlr cables just bad, or am I missing something. I'm really sorry if the answer is something simple its just I am new to this and I haven't been able to find anything online.

Edit 1: I didn't list the mics or the mixer that was my bad. The mics are behringer XM1800S which are dynamic mics. The mixer is a behringer mx400. It is a line mixer and from what I understand mics done have a line level signal. Is the XLR to 1/4" cable giving it a line level signal that the regular XLR cables aren't? I really just want to make sure my cables aren't bad.

Answer 1

You don't say what your microphone is, you don't say what your XLR-to-1/4 adapters look like, you don't say what your XLR-to-1/4-plug cable looks like, you don't say what lengths the cable have.

So there will be handwaving and guesswork involved in any answer. Your minimixer does not have preamps according to you, and your setup will not provide phantom power. So you are either working with dynamic microphones or battery-power ones. Without a preamp, probably the latter.

The typical XLR-to-1/4" adapter has a TRS (tip-ring-shield with three contacts) plug. Your mixer likely has a mono receptacle. There is some likelihood of those combining non-optimally. In contrast, a XLR-to-1/4" cable tends to use an unbalanced cable and use a TS plug (tip-shield with two contacts).

This could be a difference. Or the difference could be the other way round. Or one setup involves pin 1 from the XLR (ground) and the other doesn't and uses only 2 and 3. Or conversely one setup, because of plug incompatibilities, ends up not using 3 (cold) from the microphone.

Without you volunteering any detailed information, that's basically what I can currently think of throwing out there. Take a look. And/or take a multimeter and see what arrives where and what not.

Answer 2

According to the specs, the XM-400 mixer has unbalanced (TS) inputs and outputs. Your plugs apparently are balanced (TRS). This combination is unreliable: the S of the socket might make contact with either R or S or both on the plug. For best (meaning least bad) results, you want both.

You might try to use a passive DI "the wrong way round", feeding its "output" with the balanced low-impedance microphone signal and connecting its "input" with a short mono TS cable to your mixer (active DIs don't work in that direction). However, the XM-400 has 4.7kOhm inputs: this makes it inadvisable to use DIs with high impedance "inputs" (like intended for guitars) in reverse since their impedance on the unbalanced side is more like 50kOhm. The connection will still be balanced but all bets regarding the resulting frequency response are off since their transformer is then used outside its specs.

Since your mixer's input has one 0 Ohm ground connection and one higher impedance signal connection, you won't be able to make use of the common mode rejection of a balanced cable without either using a DI or actually putting a resistor matching the mixer's input impedance into your "cold" signal path while keeping a 0 Ohm connection to the "shield" of the cable.

Or you say "to heck with balanced". In that case, TRS from a balanced connection needs to connect T (hot) to the T (signal) of the TS socket, and both R (cold) and S (shield/sleeve) to the S (ground) of the TS socket.

This is likely what happens with your "good" connection anyway.

The net moral is: this mixer is not intended for balanced signals, and not intended for microphone level signals. Its input levels, balancing, and sockets are not designed for that job, and any connection made with a TRS plug will be inherently unreliable given the TS socket.

Answer 3

Ok, so like user22766 was saying, it might have to do with being balanced or unbalanced. If that adapter is unbalanced (using a TS connection) then you may pick up noise there. I assume the adapter is short though, so that shouldn't make too much of a difference. Unbalanced signal is fine if you keep it short.

For reference, this is a balanced 1/4" connection (TRS) Notice the two black lines. The first section of metal is the sleeve, then between the lines is the ring, and finally the point is called the tip. These are three separate signal paths.

Here is an unbalanced 1/4" connection (TS) on top. (The bottom is a 3.5mm connection) Notice the ring is not there anymore, leaving only two signal paths. This doesn't allow the noise rejection possible with the TRS cable.

Now, another cause could just be that you are creating more connection points. Each time you 'plug in' to something, that connection point will lose a bit of signal strength. So adding in the adapter gives you one more point of signal loss. I again feel like this wouldn't make too noticeable of a difference. Perhaps this issue combined with the last could create the difference you are noticing.

Now lastly, you say there isn't a preamp? This is not good, and will negatively affect your sound for sure (making it sound lower in volume and not as deep in the low end, just like you described). That doesn't answer the DIFFERENCE between the two signals though. Are you plugging in to the same input when using the adapter? If that's the case, then the preamp would not be the problem.

It would be helpful if you told us the name of the mixer, as that (to me) seems like the most crucial piece to this problem.