Headphones and Earphones
- Written by Chris Groppi
- Published on 23 April 2009
- Denon AH-D7000 Headphones and Headroom Ultra Desktop Headphone Amplifier
- Page 2: Design of the Denon AH-D7000 Headphones and Headroom Amplifier
- Page 3: Setup of the Denon AH-D7000 Headphones and Headroom Amplifier
- Page 4: The Sound of the Denon AH-D7000 Headphones and Headroom Amplifier
- Page 5: Measurements for the Denon AH-D7000 Headphones and Headroom Amplifier
- Page 6: Conclusions about the Denon AH-D7000 Headphones and Headroom Amplifier
- All Pages
The Denon AH-D7000 is the latest in Denon’s new sealed headphone lineup, and is meant to be the flagship model. At $1000 MSRP, it is a very expensive pair of headphones. Your $1000 does get you a very impressive amount of craftsmanship. The headphones are delivered in a very nice presentation box with a calfskin leather front and silk lining (or at least they seem like calfskin and silk; they may be synthetic). The sealed backs of the headphones are made of beautifully finished certified-sustainable rosewood, with Denon logos under the gloss lacquer. The adjustment mechanisms are made from machined magnesium for light weight, and have been engineered with the precision of a camera mechanism. The feel of simply adjusting the headband screams “high end.” The Earpads and head band are made from the same calfskin or calfskin like material used on the box cover. A Y-shaped headphone cord with fabric cladding is employed, and is made of 7N oxygen free copper wire with a ¼” stereo plug termination. 2” diameter microfiber drivers are used, with frequency response from below 20 Hz to 45 kHz.
The HeadRoom Ultra Desktop amplifier is a perfect match to these headphones. Any high performance headphone requires proper amplification. Just as you would not drive a pair of $180,000 Focal Grand Utopias with a $500 receiver, you wouldn’t want to drive a pair of D7000s with an iPod. The large driver requires power and control to achieve maximum performance. While the flat 25 Ohm performance may seem an easy load to drive, you will not get your $1000 worth without a proper amplifier. The 6”x6”x3” unit contains a stereo headphone power amplifier based on the Burr Brown OPA627 Op amp, one of the highest performance op amps available. We use these same op-amps in a preamplifier circuit for milivolt level signals in the radio astronomy instrumentation I build for my day job. They cost over $20 a piece in small quantities. These op amps are in HeadRoom’s “Max” amplifier modules, which drive both stereo channels. In addition to the Max amplifier modules, the Ultra Desktop also includes the Max DAC module, based on the AD1896 asynchronous sample rate converter and the Cirrus Logic CS4398 DAC. The SRC upsamples and pads all incoming digital data to 24-bit 196 kHz. Toslink optical and coaxial digital inputs accept signals at sample rates up to 24-bit, 192 kHz. The USB input accepts only 16 bit inputs up to 48 kHz. A super high quality ALPS volume pot controls the level, with switchable rear panel RCA outputs available for use as a preamp. Two pairs of RCA analog inputs are also available. The power supply for the Ultra Desktop amp is external. Included is the third-party Astrodyne switch-mode power supply, which can supply up to 42 W of DC power, and autoswitches for 110-220V and 50 or 60 Hz. As a $499 upgrade, HeadRoom offers their own bespoke, linear power supply. My test unit included the Astrodyne power supply.