Dual CV 5670
The Dual CV 5670 is an integrated amplifier developed for the high-fidelity market under the Audiophile Concept line.
It features a dual-mono style power supply with a large toroidal transformer and four filter capacitors of 8200µF.
The power amplifier uses four output transistors per channel (2SD1047 and 2SB817) in a classic emitter-follower push-pull configuration. Speaker protection is handled by a uPC1237 circuit, with a separate relay for each speaker output.
Tone controls and loudness function are implemented in a classic design. Additional features include a Tone On function that allows the tone controls to be engaged, a CD Direct mode for a shorter signal path during CD playback, and an MC Phono input option enabling selection between MM and MC cartridges.
The soundstage is clean and accurate. Overall build quality is very good, and the internal components are easily accessible. With a maximum power of 100W per channel at 8Ω, this amplifier can easily drive even demanding speakers.
Manufacturer: Dual
Status: Active company
Official website: dual.de
Service manual: ServiceManual_CV5670.pdf
General Specifications
Maximum power (8Ω): 100WFrequency response (-3dB): 9Hz-95kHz
THD (1kHz): <0.01%
Signal to noise ratio (Line): 100dB
Signal to noise ratio (MM): 80dB
Crosstalk attenuation: 80dB
Input sensitivity (Line): 200mV
Input sensitivity (MM): 2.5mV
Speaker load impedance: 4Ω-16Ω
Dimensions (WHD): 440×142×303mm
Weight: 9.5kg
Produced: 1989-1992
Initial price: 900DM
Measured Values
Maximum power (8Ω): 106WFrequency response (20Hz-20kHz): <0.5dB
Channel imbalance: <1.0dB
THD (1kHz, 1W): 0.012%
THD+N (1kHz, 1W): 0.019%
THD (1kHz, 20W): 0.0012%
THD+N (1kHz, 20W): 0.0014%
IMD (70Hz, 5kHz, 1W): 0.043%
Noise: -66.4dB
Amplification: 133.4
DC offset L: -16.3mV
DC offset R: -13.3mV
Factory Specification Sheet
Factory specification images are sourced directly from the device's original service manual or user manual. These documents are produced by the manufacturer and provide authoritative information on the product's specifications.
Maximum Power
Maximum power is measured using 8Ω resistors on both channels. A 1kHz sine wave input signal is applied and gradually increased until higher harmonics rise significantly. Typically, this is the point at which output clipping occurs.
Frequency Response
Frequency response is measured using several equilizer settings. 'Flat' indicates the tone controls are either turned off or set to their neutral position. 'Max' and 'Min' refer to the maximum and minimum tone control positions, respectively. In the phono section, the expected response follows the RIAA equalization curve.
Residual Noise
These graphs display the noise levels at various volume positions. To eliminate any interference from the input signal, the input lines are shorted during the measurement. Generally, the noise is highest at the mid-point of the volume range (50%)
Distorsion
Total harmonic distortion (THD) is measured using a 1kHz sine wave input, with the output level adjusted to meet different conditions. Intermodulation distortion (IMD) is measured using 'two sine' input signal. THD versus voltage is measured with a 1kHz sine wave input, while THD versus frequency is measured at various output levels.
