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Soundcraft EPM6 stereo channels gain control
djtetei
Posts: 4
I have a Reloop RMX 60 Digital DJ mixer with balanced XLR master outputs and when I connect it to the Soundcraft EPM6 Stereo 1 or Stereo 2 channel strips, the signal level is already at the nominal level (0 dB mark on the level meters), although the channel strips input gain is set at minimum -20 dB (all the way to the left) and the channel fader is set to 0 dB.
The Soundcraft EPM6 technical specifications states that the Stereo 1 and Stereo 2 inputs are balanced.
The Reloop RMX 60 balanced XLR master outputs are connected to the EPM6 stereo input with Cordial CFM FV XLR female to TRS cables.
The RMX 60 mixer balanced master output impedance is 600 ohms.
Why the audio signal is so loud when I use the balanced connection?
If I connect the RMX 60 unbalanced master outputs to the EPM6 stereo inputs with RCA to TS cables, the gain control on the EPM6 offers more control over the input signal.
The Soundcraft EPM6 technical specifications states that the Stereo 1 and Stereo 2 inputs are balanced.
The Reloop RMX 60 balanced XLR master outputs are connected to the EPM6 stereo input with Cordial CFM FV XLR female to TRS cables.
The RMX 60 mixer balanced master output impedance is 600 ohms.
Why the audio signal is so loud when I use the balanced connection?
If I connect the RMX 60 unbalanced master outputs to the EPM6 stereo inputs with RCA to TS cables, the gain control on the EPM6 offers more control over the input signal.
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Comments
Why the input channels gain controls do not have an unity gain position?
I checked a Soundcraft Ui12, which has a normal 600 Ohm symmetrical output (like your Reloop), and I connected it with the service EPM6.
Here is their response:
"Indeed, if the Ui is set to the usual -9dB average signal level, with the gain control completely turned down, we have an average signal level of 0dB on the analog console.
So we can say that everything is working fine.
If this is not good for you, you need to gain back the Reloop if you want to control the signal level on the EPM.
Best regards,
BALAZS SZENDE
Supervisor, Technical Support Engineer EMEA
Harman Professional Solutions"
The Soundcraft technical engineer mentioned in his reply that he used a Soundcraft UI 12 mixer as a source, because it had a 600 ohm output impedance, but the user manual technical specifications for UI 12 states that all its outputs have an impedance of 100 ohm.
I still have an issue with the EPM 6 stereo input stage, because any mixer should mention a nominal working level for the input stage to allow the user to assess which sources output levels can connect without overloading the mixer input stage (suppose one may use a DAC with no built-in preamplifier).
Take the Soundcraft EPM6 as an example: its stereo input stage gain range is between -10 dB and +20 dB, meaning that, inside this range, should be a unity gain point, where the input signal is neither boosted or attenuated. The EPM 6 inputs don't have the unity gain point clearly marked on the scale.
Actually, except for the Soundcraft Notepad series or other models with simetrical positive and negative gain control, where the 0 dB point would be at 12 o'clock position, all other Soundcraft mixers tend to have the 0 dB attenuation point around 11 o'clock position, which, I suppose, it is the case with the EPM 6 mixer too.
If I were to use this point as a guide and feed the Reloop RMX 60 balanced master output nominal level (0 dB lon the the meters) to the EPM6 balanced stereo inputs, the PFL input signal level is hitting +10 dB on the EPM6 level meters, and +6 dB on the Behringer FBQ 6200 HD level meters, which is high for mastered music.
In my opinion, it may have something to do with the EPM 6 stereo input sensitivity (nominal level) being to high, even with -10 dB gain attenuation.
It seems like it has been designed for sources with low output level, like consumer devices with -10 dBV nominal output levels.
On the Reloop RMX 60 side, I sent both 400 Hz and 1 kHz test tones to its RCA inputs, set the channel gain for a reading of 0 dB on the individual channel meter, set the master output level for a reading of 0 dB on the master output level meters and, using a multimeter, able to measure frequencies in the 10 Hz-10 MHz, set to read Volts AC true RMS, I measured the output signal voltages at the TRS connector side, between tip and ring, tip and sleeve, ring and sleeve. The voltage reading between tip and ring was 1.22 Vrms and between tip-sleeve or ring-sleeve the voltage readings were simetrically equal and half the value of 1.22 Vrms