June 2019

 

With the purchase of the Lynx Aurora 32 with no microphone input, I needed to find a dual phantom power, inexpensive microphone preamp.

Being 64 channels (32 in and 32 out), the back plate of the Lynx Aurora is already full, so buying the Lynx four channel microphone card wasn't possible, no room for it. What a bummer!  

 

Why I purchased the Behringer UMC204HD:

·         My current USB MiniDSP UNIMIK-1 microphone doesn't support high sampling rates, hence limiting measurement to 20 kHz.

·         I wanted to gain precision when measuring (aiming for 100 kHz for tweeter measurements). 

·         Behringer U-Phoria UMC204HD (USB powered and supporting 192 kHz sampling) will permit measurements up to 96 kHz.

·         Because this interface will be data acquisition only (just used for measuring), subjective sonic qualities were not an important factor.

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Bonus when buying a Behringer product:

·         The good thing when buying a Behringer is that your credit card statement won't bulge too much.

·         It comes with a nice promotional Behringer yellow sticker. If you apply the sticker onto your car, it acts as a visual deterrent for potential car thieves. They’ll see the sticker and simply assume you're totally broke and have only Behringer stuff in the trunk. Out of pity, they’ll probably target another vehicle instead. LOL

·         Like most audiophiles, I share one thing. PRIDE. As a result, I put the promotional sticker where it belongs… in the garbage.

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I see the UMC204HD as temporary only. 

I’m planning on either a DIY killer dual microphone preamp or purchasing a great microphone preamp later on.

Commercial offerings for microphone preamplifiers are a very pricey option for what you actually get. The DIY is a no brainer here.

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The odds are strong that I'll re-sell the Behringer so advanced modifications aren't likely to happen, despite serious flaws in the design. After all, it’s a budget component, and you always get what you pay for. There’s never a free lunch in audio.

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The Good: 

·         Phantom power seems good, as I measured a solid 46.2 VDC instead of the supposedly 48 VDC. It measured within ~3% off the 48V mark. So, not bad at all, considering some interfaces give less than 30 VDC while still claiming phantom power, that is just 62% of what it is supposed to be.

·         Despite the price, it doesn’t feel super cheap. Rather, it feels more like mid-grade quality with its aluminum frame. There’s no plastic outer case.

·         For data acquisition, the microphone signal travels probably through two coupling capacitors and maybe a single set of opamps, and then is immediately sent to the A/D chip, and then digitally to the computer via the USB. Most of the analog stages aren't used, thereby minimizing distortion.

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The Bad:

·         All connectors are of unknown origin and reliability. No Neutrik here for sure. I hope those Chinese plastic things will properly contact for my limited use (I don’t tour, so once my microphone is connected, it won't come off very often.

·         The power supply is dismal at 5Vdc from the USB port and a single, small LC filter for all. (single voltage operation).

·         The potentiometer (volume knob) is very cheap. No Noble or ALPS for sure, but signal is passing through them nevertheless. If I was to keep the unit, I’d bypass most of them.

·         Most chips (opamp, DAC) aren't adequately bypassed on the power supply rail. Likely used a tiny ceramic cap instead, as the value is way too low.

·         The opamps are low cost and very, very low performance (ad8694, NJR4580 and NJR2212). Even the dreaded 42 year old NE5532 seems "state of the art" in comparison to the crap Behringer opted to use.

·         The headphone jack is not suited for low impedance and can't reach high levels, due to insufficient power supply capacity, not a real issue for me as I'll never use the headphone output.

·         All inputs and outputs are capacitively coupled by cheap generic Chinese capacitors. A good upgrade would be to do a total recap of the entire unit with low ESR capacitors.  Remember, we're talking Behringer here, so they use real low quality capacitors!

·         Additional negative comments stopped, due to lack of time :)

 

I haven't seen the schematic of the 204HD. However, given other MIDAS preamps I've checked from same generation Behringer product lines, the MIDAS circuitry brand is nothing special. Really nothing special. A selling feature that has nothing to do with performance.