This is a review and technical measurements of the ROLLS Promatch two-way XLR to/from RCA converter with gain control. It is on kind loan from a member and costs US $56 to $69 from sellers on Amazon.
The box is descriptive enough:
The positions you see on the controls is what I had to set them to in order to have 2 volts on RCA and 4 volts on XLR.
An external 15 volt, 500 milliamp switching power supply gives it the juice to operate:
ROLLS Promatch Review (RCA to XLR)
We often have a need to feed a balanced amplifier using unbalanced RCA output from our sources. Let's see how transparent the Promatch is in this configuration:
Well, it is not broken but nothing to write home about either. SINAD was jumping up and down from 98 to 101 dB for some unknown reason (noise?). Distortion is quite low though at -120 dB. Channel match is poor though as you can also see in frequency response measurement:
I would have wanted ruler flat response to 20 kHz at least but we don't get that.
Signal to noise ratio is sufficient for 16 bit sources:
Crosstalk was especially poor:
Promatch XLR to RCA Conversion Measurements
Switching the device around and feeding it 4 volts to get 2 volts produced horrible results:
That's because the top of the waveform is clipped. Sweeping the input voltage we see that it can't handle more than 3.8 volts or so:
Shame as our desktop hi-fi DACs output 4 volts and some even more. If you do use them, be sure to turn them down 0.5 to 1 dB either in software or hardware volume control.
Frequency response is just as bad as before except now it droops in low frequencies as well:
SNR is the same:
Conclusions
As with other ROLLS products we have tested, these are "problem solver" boxes and not meant for great performance. For that use they are fine. For our use where we want transparency, I am afraid you are not going to get that.
Overall, I can't recommend the Promatch but depending on your application, it may be fine and quite a bargain.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The box is descriptive enough:
The positions you see on the controls is what I had to set them to in order to have 2 volts on RCA and 4 volts on XLR.
An external 15 volt, 500 milliamp switching power supply gives it the juice to operate:
ROLLS Promatch Review (RCA to XLR)
We often have a need to feed a balanced amplifier using unbalanced RCA output from our sources. Let's see how transparent the Promatch is in this configuration:
Well, it is not broken but nothing to write home about either. SINAD was jumping up and down from 98 to 101 dB for some unknown reason (noise?). Distortion is quite low though at -120 dB. Channel match is poor though as you can also see in frequency response measurement:
I would have wanted ruler flat response to 20 kHz at least but we don't get that.
Signal to noise ratio is sufficient for 16 bit sources:
Crosstalk was especially poor:
Promatch XLR to RCA Conversion Measurements
Switching the device around and feeding it 4 volts to get 2 volts produced horrible results:
That's because the top of the waveform is clipped. Sweeping the input voltage we see that it can't handle more than 3.8 volts or so:
Shame as our desktop hi-fi DACs output 4 volts and some even more. If you do use them, be sure to turn them down 0.5 to 1 dB either in software or hardware volume control.
Frequency response is just as bad as before except now it droops in low frequencies as well:
SNR is the same:
Conclusions
As with other ROLLS products we have tested, these are "problem solver" boxes and not meant for great performance. For that use they are fine. For our use where we want transparency, I am afraid you are not going to get that.
Overall, I can't recommend the Promatch but depending on your application, it may be fine and quite a bargain.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/