XLR (male) to TRS problem

Question

Yesterday I bought a couple of studio monitors (Adam T7V) which should suppose to sound great if connected to my focusrite 2i2 with balanced wires (TRS to XLR male). So I soldered a couple of wires using this scheme:

The cables sound fine (I think) except the fact that the volume of the speakers is way lower than a RCA cable used as comparision ( I had to turn the knob on the rear of the speakers at full to hear a decent volume!). What did I do wrong? Could it be a bad soldering or maybe the RCA unbalanced cable is really supposed to have at least double volume of a balanced solution?

Answer 1

From the manual for your monitors:

A balanced XLR connector and unbalanced RCA jack allow connection to professional mixers and I/O boxes using +4 dBu or -10 dBV nominal operating levels

While the wording is odd, those level figures are the different standards in “professional” vs. “consumer” line level connections. The "pro" standard is about 12 dB higher when converted to common units.

Therefore, if you are comparing the two inputs using adapter cables from the same source output, the problem is that the monitor's input is expecting a much higher typical input level on the balanced input than on the RCA input, and the volume control and any fixed gains are calibrated differently to provide a useful range for each input's typical levels.

(If when making the RCA connection you are using the balanced output in unbalanced fashion by leaving the inverted signal unconnected, then that gives half the amplitude, which goes in the opposite direction from the difference you're hearing, but that's only −3 dB.)

In conclusion: this is normal and you should leave it be, or if you need more volume, see if you can increase the output level from your audio interface or software.

Answer 2

There's nothing 'second rate' about the phono input, though an unbalanced connection is more vulnerable to noise pickup. If this isn't a problem in your setup, and using the phono inputs allows a more managable gain structure, use them. You could turn the Monitor control on the Focusrite full up. But it seems a bit silly to amplify a signal just so that you can attenuate it at the next stage (which is what you're doing by choosing the XLR input) then re-amplify it!