Audio Research D-70

Tube stereo power amplifier

FRONT PANEL : Anodized silver or black. Line fusing. Line led indicator. Power switch. Circuits led indicator. Circuit fusing. (The left led indicator lights when power is applied, and the other comes on once the 320V line has reached a threshold voltage, which takes a second or two. This latter indicator works as a monitor for the series regulator circuits.

BACK PANEL : Channel 2 speaker output (4-8-16 Ohms) – Channel 2 / 1 inputs – Channel 1 speaker output.

ARC introduced D-70 in 1983. In 1984 were introduced his new version D-70 MKII which has different tube complement.

D-70

D-70 MKII

TUBES:

D-70: (7) 6922, (4) 6550, (1) 6550, (1)12AX7

D-70 MKII: (3) 6922, (4) 6FQ7, (4) 6550, (1) 6550, (1) 12AX7

Size 19" W x 7" H x 16.5" D. Weight 49 lbs.

ELECTRICAL

Tube stereo power amplifier.

60w/ch at 16 Ohms.

Response: 15-30kHz (-3 dB points) (D-70 MKII)

Distortion : less than 1 % (typically less than .005% @1W) (D-70 MKII).

Overall negative feedback : 20.5 dB (D-70 MKII)

Output impedance: 4, 8 and 16 ohms.

Damping factor: 15 (D-70 MKII).

Slew rate : 10 V/µs (D-70 MKII)

Power supply : 600 w (max) (140 joules)

Year of introduction: 1983 (D-70) – 1984 (D-70 MKII)

CARATTERISTICHE

Finale stereo a valvole

60w/ch a 16 Ohm

Risposta in frequenza 15-30kHz (-3 dB points) (D-70 MKII)

Distorsione : meno di 1 % (tipicamente inferiore a .005% @1W) (D-70 MKII).

Overall negative feedback : 20.5 dB (D-70 MKII)

Output impedance: 4, 8 and 16 ohms.

Damping factor: 15 (D-70 MKII).

Slew rate : 10 V/µs (D-70 MKII)

Consumo : 600 w (max) (140 joules)

Anno di inizio di produzione: 1983 (D-70) – 1984 (D-70 MKII)

Are available on request :

Schematics and parts list.
The abstracts of testings performed by Italian hi-fi magazine Suono (no.141,1985) - (no.163,1986)

Sono disponibili su richiesta :

lo schema elettrico e il catalogo dei ricambi.
l'estratto della prova tecnica eseguita dalla rivista Suono (n.141,1985) - (n.163,1986)

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