This is a review and detailed measurements of the Henry Engineering The Matchbox HD unbalanced to/from balanced active converter. It was kindly drop shipped to me by a member and costs US $250.
While stamped steel, the box is heavy and sturdy which fits the purpose. Trims are provided to adjust levels and internally there is a high-gain mode. Nice to see power supply built-in although the cord is darn thick and heavy for little power this box needs:
For testing I focused on RCA to XLR since many want to hook up amplifiers with unbalanced out to an amplifier with only balanced input.
EDIT: added the reverse conversion measurements as well.
The Matchbox HD Performance Measurement
I hooked up RCA out at 0.83 volts to get nominal 4 volts out of XLR connection:
Performance is really good in one channel but not as much in the other. That one shows more power supply interference which can sometimes be a grounding issue. But no matter what I tried, I could not impact it a bit. This may be in all units or something specific to this sample. Still, at SINAD of 97 dB it beats the company spec and clears 16 bit hurdle. Noise performance is very good:
Frequency response is excellent:
Crosstalk could be better:
IMD distortion is very good in the good channel:
As is THD vs level:
Wideband response shows rising distortion at highs:
EDIT: Matchbox HD XLR to RCA Measurements
I was asked to measure balanced to unbalanced. I would personally use a simple adapter/cable unless you need adjustable levels. But here it is anyway:
As with balanced, I could not get rid of power supply noise but distortion is incredibly low here at -120 dB. So the only penalty is noise:
Which is not bad at all. Frequency response is even flatter:
Distortion is the same in both channels which again is superior to the reverse conversion:
So all in all, very good performance in this direction.
EDIT2: The Matchbox HD Converter Teardown
As requested, here is a look at what is inside:
I suspect the increased mains noise in the RCA to XLR is due to latter being right next to the linear power supply and its cord.
Otherwise, this seems like a very clean lay out with due attention to safety given that cut out isolation of high voltage vs low although the output XLRs should have been on the other side of the moat.
Conclusions
Buffered converters avoid many of the issues of passive devices and we have an example of that here. While one channel is weaker overall performance is still very good, some of the best we have measured.
I am going to recommend Henry Engineering The Matchbox HD. A bit expensive but flexible with good performance.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
While stamped steel, the box is heavy and sturdy which fits the purpose. Trims are provided to adjust levels and internally there is a high-gain mode. Nice to see power supply built-in although the cord is darn thick and heavy for little power this box needs:
For testing I focused on RCA to XLR since many want to hook up amplifiers with unbalanced out to an amplifier with only balanced input.
EDIT: added the reverse conversion measurements as well.
The Matchbox HD Performance Measurement
I hooked up RCA out at 0.83 volts to get nominal 4 volts out of XLR connection:
Performance is really good in one channel but not as much in the other. That one shows more power supply interference which can sometimes be a grounding issue. But no matter what I tried, I could not impact it a bit. This may be in all units or something specific to this sample. Still, at SINAD of 97 dB it beats the company spec and clears 16 bit hurdle. Noise performance is very good:
Frequency response is excellent:
Crosstalk could be better:
IMD distortion is very good in the good channel:
As is THD vs level:
Wideband response shows rising distortion at highs:
EDIT: Matchbox HD XLR to RCA Measurements
I was asked to measure balanced to unbalanced. I would personally use a simple adapter/cable unless you need adjustable levels. But here it is anyway:
As with balanced, I could not get rid of power supply noise but distortion is incredibly low here at -120 dB. So the only penalty is noise:
Which is not bad at all. Frequency response is even flatter:
Distortion is the same in both channels which again is superior to the reverse conversion:
So all in all, very good performance in this direction.
EDIT2: The Matchbox HD Converter Teardown
As requested, here is a look at what is inside:
I suspect the increased mains noise in the RCA to XLR is due to latter being right next to the linear power supply and its cord.
Otherwise, this seems like a very clean lay out with due attention to safety given that cut out isolation of high voltage vs low although the output XLRs should have been on the other side of the moat.
Conclusions
Buffered converters avoid many of the issues of passive devices and we have an example of that here. While one channel is weaker overall performance is still very good, some of the best we have measured.
I am going to recommend Henry Engineering The Matchbox HD. A bit expensive but flexible with good performance.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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