How much power does the Audio Research I/70 have?
The Audio Research I/70 delivers 70 watts x 2 channels continuous from 20 Hz to 20 kHz, typically 1% THD at 1 kHz and below 0.1% at 1 watt.
Does the Audio Research I/70 use vacuum tubes?
Yes. The Audio Research I/70 is an all-valve amplifier: vacuum tubes do the amplifying from input to output. It runs 4x KT120 output, 3x 6922 (one input, two driver) input.
Does the Audio Research I/70 need biasing?
Biasing is Auto-bias. That means the amplifier sets the operating point of each output valve itself, so there is nothing to adjust and nothing to measure - you can change tubes without a meter or a screwdriver.
How long do the tubes in the Audio Research I/70 last?
Output valves are a consumable. In normal domestic use a set lasts somewhere between about 2,000 and 5,000 hours - a few years for most people - and they degrade gradually rather than failing outright. Input and driver valves last far longer, often the life of the amplifier. Check the warranty card before you buy: valves are almost never covered by the amplifier's own parts warranty, and are usually warranted separately for 90 days to a year.
What speakers suit the Audio Research I/70?
A valve amplifier is judged on the speaker's sensitivity, not just on watts. At 70 watts, the safe rule of thumb is a speaker of about 88 dB or better - an insensitive speaker will run out of headroom long before the amplifier sounds bad. It also has 4 / 8 ohm output transformer taps. A valve amplifier has no minimum impedance the way a transistor amplifier does; you match the tap to the speaker, and a speaker whose impedance swings a long way will shift the tonal balance slightly because a valve amplifier follows that curve.
What amplifier class is the Audio Research I/70?
The Audio Research I/70 uses a Class A/B amplifier design. Class A/B is the traditional linear design: it runs warmer and is less efficient than Class D, but it is long valued for its natural, low-distortion sound.
Does the Audio Research I/70 have a built-in DAC?
No. The Audio Research I/70 has no built-in DAC, so a digital source such as a streamer or CD transport needs its own converter, or you connect it over analogue.
Can I connect a turntable to the Audio Research I/70?
No. The Audio Research I/70 has no phono input, so a turntable needs an external phono preamp (or a deck with one built in) before it can be connected.
Does the Audio Research I/70 have Bluetooth?
No. The Audio Research I/70 does not have Bluetooth built in; you would need an external Bluetooth receiver connected to one of its inputs.
Does the Audio Research I/70 have a headphone output?
Yes. The Audio Research I/70 has a Yes-inch headphone output on the front panel for private listening.
How much does the Audio Research I/70 cost?
The Audio Research I/70 has a manufacturer's list price (MSRP) of $9,950.