AA DMI 3H

This Audio Alto’s compact series reflects maximum effort and knowledge, as it presents quite a different solution with its built-in electronic tubes as voltage amplifiers. Result of design and construction is its acoustic-inertial and elegant shape.

The AA DMI 3H is designed as dual mono amplifier and with modularly design enables an insertion of different input modules (Phono RIAA MM/MC etc). AA DMI 3H power supply is realized with two 150VA toroid transformer with a electrostatic and magnetic screen that provides with also doubled electronic regulators power to each set of the amplifier individually. Heating of electronic tubes is regulated and is time-controlled for optimum operation and for achieving their life expectancy of over 5.000 hours. Power supply voltage for tubes is time delayed and regulated.

User Manual (PDF)

Beauty of sound

All the internal voltage amplifier stages work in Class A mode of operation. The input stages are realized with low noise low distortion circuits and are also working in class A mode. The power voltage amplification is realized with a double triode vacuum tube configured in CCDA (Constant Current Draw Amplifier) single ended topology to eliminate the supply voltage fluctuations due to audio signal changes. The selected tube 6922 or E88CC (NOS 6DJ8) are among the best audio triodes providing low input capacity, high standby current, low output impedance and very low distortion levels without negative feedback. The vacuum tube glass is dumped with a special silicone ring.

To obtain detailed pricing information, please contact us.

Handmade

AA DMI 3H is handmade and all components are tested prior to installation.

A complementary MOSFET output transistor transforms the CCDA output with output impedance of few hundreds of ohms to low impedance (high current) output required by speakers. The output transistors are biased with an innovative dedicated circuit that keeps both output transistors biased during the whole signal phase (360°) reducing the low power related distortions (no typical class A/B turn off/on that is the cause of unpleasing crossover distortion).The circuit significantly reduces the distortion caused by the effects of nonlinear transconductance in the output transistors resulting in a sound identical as it would be produced with an pure class A output stage.

The voltage and current amplifiers work without any global negative feedback!

Inputs
I2 – RCA 220Kohm, 500 mVeff sensitivity (line input), Noise -95dB
I3 – RCA 220Kohm, 200 mVeff sensitivity (line input), Noise -95dB
Tape in – RCA 220Kohm, 200 mVeff sensitivity (line input), Noise -95dB
Output
Tape out – RCA, 200 mVeff
Headphone – 0.9 Veff @ 32 Ohms
7,5Veff @ 600 Ohms
4 x Speakers posts 4 mm
Gain
30 dB (70 dB Phono MM)
Output Power
Model A: 2 x 30W @ 8 Ohm, 2 x 50W @ 4 Ohm

Model B: 2 x 60W @ 8 Ohm, 2 x 100W @ 4 Ohm

Frequency response
5Hz to 60.000Hz -1dB
Vaccum tubes
2 x 6922 (E88CC or NOS 6DJ8)
Dimensions
(W x D x H) 295 x 465 x 93 mm
Weight
12.5 Kg
Finish
Dark Shadow, Silver, Inox, Chrome, natural solid wood (i.e. walnut)
or upon special order in various colors

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