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Core Sound HeadLine
HeadLine Specifications

(Last updated 03/20/2007)
  • Channels: 2
  • S/PDIF Digital Inputs: 3 (two RCA coaxial jack, one Toslink optical jack)
    • Word width: 16 to 24-bits
    • Sample rates: 32 to 192 KS/s
  • Analog Input: 1 pair, stereo Line level (dual RCA jacks)
  • Headphone Output: 1/4-inch stereo phone jack
  • Line Outputs: 1 pair, stereo Line level (dual RCA jacks)
  • Controls and Indicators:
    • Power Off/Line/Both Line & Headphone Select
    • Headphone Level, continuously variable
    • Analog/Digital Source Select
    • Digital Source Select
    • S/PDIF Data Valid LED
    • Power Supply Voltage Status LED
  • Line output specifications:
    • Frequency response: typically 20 Hz to 20 KHz, +/- .1 dB
    • Noise floor: typically -135 dBFS
    • THD+ Noise: typically -105.5 dBA (< .00053%), 22 Hz to 30 KHz
    • Crosstalk: typically better than 112 dB @ 1 KHz; better than 85 dB, 20 Hz to 20 KHz
    • Output for 0 dbFS input: 1.88 Volts RMS (5.48 Vp-p/7.7 dBu)
  • Headphone output specifications
    • Output impedance: nominally 11 Ohms
    • Driving 600 Ohm headphones (e.g., AKG 240DF)
      • Frequency response: typically 20 Hz to 20 KHz, +/- 0.1 dB
      • Noise floor: typically -136 dB
      • THD+N (A-weighted): typically -98 dBA, .0013% at 700 mV RMS (low listening level), .005% at 8 Vpp (way, way too loud)
      • Separation: typically -93 dB @ 1 KHz
      • Output voltage: more than 5 Volts RMS (!)
    • Driving 25 Ohm headphones (e.g. Sony 7506)
      • Frequency response: typically 20 Hz to 20 KHz, +/- 0.1 dB
      • Noise floor: typically -136 dB
      • THD+N (A-weighted): typically -93 dBA, .0018% at 200 mV RMS (very loud), .005% at 850 mVpp (way, way too loud)
      • Separation: typically -93 dB @ 1 KHz
      • Output voltage: more than 800 mV RMS
  • Battery complement: two 9 Volt alkaline "transistor radio" batteries (type 1604)
  • Operating time for two batteries: 5 hours minimum at full load (Line and Headphone outputs driven; 12 hours typical for Line output only; (batteries may be hot-swapped for unlimited continuous operation)
  • External power supply: 7 to 16 VDC @ 250 mA (minimum) via 5.0/2.1 mm DC power jack
  • Dimensions: 1-3/8"H x 6-9/16"W x 3-3/4"D (34.9mm x 166.7mm x 95.3mm)
  • Weight: 10.5 ounces (300 grams)
Each and every HeadLine is subjected to eighteen tests using an Audio Precision System Two Cascade before it ships to you. Core Sound is one of the few companies that tests its products this rigorously to guarantee that your HeadLine is as good as it can be.

HeadLine's frequency response is uncommonly flat and extended. With a -0.1 dBFS 24-bit/44.1 KS/s digital signal driving, here's HeadLine's Line-level output's frequency response:

Note the very expanded vertical scale on this graph. If we didn't expand the scale you would never see the roll-off. The frequency response is extremely flat, typically varying less than plus-or-minus one-tenth of a dB. (We've separated the two channels by a fraction of a dB so that you can see both of them.)

HeadLine's THD+N performance is also uncommonly good. Being driven by a -0.1 dBFS 24-bit/44.1 KS/s digital signal to an analog output level of 8 dBu (around 2 Volts RMS -- a very loud Line level), the noise baseline is typically more than 140 dB down from the signal, and the highest harmonic is more than 105 dB below the signal. That's .00055%!

Channel separation is typically more than 115 dB at 1 KHz and more than 85 dB at 20 KHz. Again, this is outstanding performance!

Configuration Jumpers

HeadLine has two internal user-configurable jumpers.

The first jumper controls the bandwidth of the phase locked loop (PLL) on the S/PDIF receiver. Some S/PDIF source devices (e.g., computer sound cards, CD players) have excessive jitter on their outputs. For folks who are listening to those devices the filter should be set to Wide Band; otherwise its PLL make may lose lock and mute.

For those who have high quality digital audio sources, this jumper should be set to Narrow Band. Setting this to Narrow Band gains another 1.5 dB of S/N ratio (up to 106.5 dB from 105 dB). To ensure that HeadLine works with all digital audio data sources, it ships with this jumper in the Wide Band position.

The second jumper controls whether non-critical digital audio data errors are flagged by lighting the red LED. Scratched or dirty CDs often have lots of data errors. The errors are not critical because they are corrected and not audible. If you want to be alerted to these errors, set this jumper to the other position.

Notes About Headphone Quality

In designing and testing HeadLine we discovered that some headphones are considerably better than others, and not just in the ways you'd expect (e.g., sound quality, distortion, sensitivity).

Some headphones have inherently very poor crosstalk specifications and can degrade even the best amplifier's noise and distortion specifications.

For example the very popular Sony MDR-7506 headphone's coiled cable and drivers degrade crosstalk between channels to -56 dB, the noise floor degrades to -126.5 dB and the THD+N specification degrades to -92 dB. Interestingly, if instead of using HeadLine to drive them, you used a Mackie 1202 mixer (or other similar quality headphone amplifier) to drive them, the crosstalk specification is degraded about another 10 dB! (The Sony MDR-7506 'phones have a nominal 30-Ohm impedance; we measured these specifications while driving them with 100 mVp-p signal, which is pretty loud.)

So while HeadLine is capable of incredibly high levels of performance, if you use headphones that can't take advantage of it, you'll get degraded performance.

Another example: compare the -7506's performance with the 600-Ohm AKG K240DF professional studio headphones. With the AKG, crosstalk is around -93 dB (compared to the Sony's poor -53 dB), noise floor is around -136 dB (compared to the Sony's still-pretty-good -126.5 dB), and THD+N is down around -96 dB (compared to the Sony's -92 dB). (We measured the AKGs while driving them with a 2 Vp-p signal, again pretty loud.)

So if sound quality matters to you, pick your headphones carefully!


For pre-sales consulting or to place an order, call Core Sound at 1.888.538.6744 or 1.201.801.0812.

"Core Sound Microphones" is a trademark of Core Sound, LLC
"Core Sound" is a trademark of Core Sound, LLC
"PDAudio", "TetraMic", "HeadLine", "2Phant" and 4Mic are trademarks of Core Sound, LLC
Thanks to HK Audio for use of their open-air concert photo. Mossman photo ©2004 OceanBridge Communcations.
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