Pro Audio Review (April 1998)
By Russ Long
I was sold on Demeter Amplification when I first heard the company’s all tube direct box in 1990. I immediately purchased one for myself and since then purchased two more one for each of my studios. Needless to say, I was curious when I heard about the new H-Series line of Demeter products, which includes the HM-1 two channel microphone preamp, HC-1 single channel tube compressor and the EQ-1 two-channel three-band parametric equalizer. The concept behind Demeter’s H-Series circuit design is to utilize tube circuitry for all the amplification functions and solid stated design for all of the driver functions. This blend of technologies results in tube sound, yet still affordable equipment, but does it uphold the Demeter tradition?
Features
For microphone input, the rear panel of the HM-1 includes both female XLR connectors and 1/4″ TRS jacks. For instrument level input, the unit’s front panel is equipped with a pair of 1/4″ mono jacks. Balanced signal output (maximum +28 dBu into 600 ohms) is accessible at the rear panel via two make XLR connectors or two 1/4″ TRS jacks. All of the HM-1’s XLR connectors are wired pin two hot. The rear panel is also equipped with a voltage selector giving the user the ability to easily switch between 115 and 230V.
The HM-1 has a choice of switch-controlled options accessible from the front panel. the low-cut switch insets a 6 dB per octave rolloff at 120 Hz. I am so pleased the a 6 dB per octave rolloff sounds far better than one measuring 12 dB or more per octave starting at 40 or 60 Hz (and generally has less phase shifting).
The Demeter’s low-cut is smooth and musical (translation: usable). The microphone pad switch activates a 20 dB pad. The phantom power switch activates the 48 V phantom power. The phase switch reverses the microphone’s phase at the input. Finally, the meter switch toggles the 10-segment VU meter’s sensitivity between normal and -10 dB operation.
In addition to its many switches, the front panel is also equipped with gain and volume knobs. The gain knob varies the input gain fro 30 to 60 dB and controls how hard the tube amplification circuit is hit. The volume knob trims the signal before it reaches the balanced output driver. The best signal to noise ratio is reached when using the volume at maximum, though sometimes a better sound can be achieved by turning up the gain to achieve more of a tube sound and, in turn, backing off the volume. Experimenting with different gain levels gives the use unlimited sonic options.
The HM-1 is housed in a single space, 10.5″ deep aluminum and steel enclosure that would likely rival a 747’s black box in strength. Its stated specs include a frequency response of 20 Hz-20 kHz, an input noise of -120 dB EIN, and THD with 30 dB gain of 0.020% at 1 kHz. The HM-1 utilizes quality components including film capacitors, metal film resistors and custom toroidal power transformers. The tube amplification circuit operates with 12AX7A tubes.
In Use
When put to the test the Demeter HM-1 proved itself worthy of the Demeter name. Having independent gain and volume controls is a Godsend. It allows the user to tailor the preamp’s sound to the specific circumstance. The best signal to noise ratio is achieved when running the volume wide open and keeping the gain as low as possible By increasing the gain, the tube circuit is pushed harder and it begins to give the use more of that distinct tube sound.
On vocals I found the HM-1 superb. It was warm yet still transparent. Drums sound fantastic through the Demeter. They are punchy and full sounding. I love the direct sound of the bass guitar with the gain pushed almost to the point of audible distortion. At the setting it retained its low end while achieving a presence that allowed the bass to pop out of the track without overpowering the band. I had wonderful results using the HM-1 on my grand piano. The piano retained its depth and character without losing any of its shimmer. I also had fantastic results on electric and acoustic guitars, as well as banjo and mandolin.
Summary
From the project/demo studio to the country’s finest rooms, the Demeter HM-1 fills a niche at a price well within reach and provides sound quality and flexibility that are top notch.