Do 2 channel audio manufacturers take headphone jack ciruits seriously, or are they an afterthought?
David Matz -- Mon, 07/05/2010 - 16:24
Headphones are a huge market. Just check Head fi.org. There's a lot of buzz and activity on that site. However, most of the headphone guys own headphone amps by smaller companies targeted toward the headphone market. Why did the the 2 channel manufacturers drop the ball?
Are their circuits not as good, or are they just neglecting marketing to the headphone niche? Any one experience Cary Xciter, Manley, or other 2 channel models? How do they compare to the focused head phone amp products by companies like Woo or Red Wine or others?
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Here is an answer from our perspective as a manufacturer:
Benchmark has been manufacturing stand-alone headphone amplifiers for studios and broadcast applications for over 20 years. When we decided to put a headphone amplifier in the DAC1 (outboard D/A converter) we took this task very seriously. The goal was to achieve headphone performance that matched the performance of the XLR outputs. This performance had to be achieved while driving two pair of headphones (not just resistive test loads). To meet these goals, it soon became apparent that we would need high drive capability, very low output impedance, low noise, and a very low distortion. The result was the HPA-2(TM) headphone amplifier. The headphone amplifier in the DAC1 is not an afterthought. It represents almost 50% of the R&D that went into the original DAC1.
Based upon our own testing, we believe our headphone amplifier may be one of the most transparent available. But, because it is built into our D/A converter, many assume that it is just a cheap add-on.
If you open up the DAC1, you will see a large toroidal transformer with associated power supply components. This power supply is excessive for a D/A converter. The main purpose of the large supply is to have enough available power to drive the headphone amplifier.
A few manufactures (like us) take their headphone outputs seriously. Most do not.
Many products do not have quality headphone outputs. The cheap solution is an opamp with a series resistor to limit the load on the opamp. This solution will result in high distortion, poor frequency response, and poor damping. Because this solution is cheap and easy, it is very common.
I have seen one product that used one of the XLR output opamps to drive the headphone jack. Plugging in a headphone significantly increased the THD at the XLR output!
John Siau
V.P. Operations
Director of Engineering
Benchmark Media Systems, Inc.
www.benchmarkmedia.com