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Description: The Art Audio Jota is a classic single-ended triode amplifier. The signal path is based on three tubes – two double triodes in the input and control stages and a power triode in the output stage. On the input we have a Philips E88CC double triode in the splendid SQ version (one of the best versions of this tube I heard), and behind those we have a further double triode, a 12BH7A EH by Electro-Harmonix working as a cathode follower and output tube driver. The output stage consists of big NOS power tubes by Aleša Vaic Vacuum Tube Technology, the AV 320B SL. The tubes are placed a bit differently than usual, with the power triodes in the front, the input tubes in the back right next to the output transformers. This is good because the signal path is shortened that way. However, for the review loaner this was less critical as it was equipped with the optional volume control. |
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This is a high-quality switch with ultra-precision resistors, one of the best of its kind. Such a passive attenuator allows resigning a preamplifier to connect the amplifier directly to the output of a CD player.
In my system however, the Jota sounded better with an external preamplifier – both my Leben RS-28CX and Ayon Polaris II showed that the Art Audio amp could do more. Directly from the CD the sound was clean and resolved but not very saturated and dynamically flat. I do not like such sound even though the better solution made the signal path longer. Fortunately, the amplifier can be ordered without the pot. |
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I mentioned the output transformers designed by Art Audio and made exclusively for them in one British factory. A special design allows for an extended frequency response and low distortion at high current. Between those two is a third big transformer for power. In front of it we see the rectifying tubes, one per channel – the model 274B whose glass envelope resembles the 300B.
All transformers have chrome-plated end bells which do not only shield but also improve aesthetics. The enclosure is silver polished stainless steel. On the back we see large heat sinks for voltage stabilizers, a singular RCA input and a pair of loudspeaker terminals (on request other configurations are possible), with the latter not particularly noteworthy – I would order WBT terminals.
The whole circuit is built on a PCB. We will find some high-class elements like precision high-power resistors, Hovland Musicap coupling capacitors and nice power supplies. The secondary windings for each channel’s power and preamplifier sections are separately wound, hence the amount of filter capacitance.
The circuit applies no global feedback loop. The machine can be ordered in many versions, with the power switch on the side (I recommend that!), with different loudspeaker terminals, different kinds of attenuator or none, with different power tubes etc. There really are many options to choose from.
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Technical data according to manufacturer:
Output power: 2 x 20 watts
Input sensitivity: 400mV
Input impedance: 200kΩ
Frequency response: 20Hz – 20kHz ± 1dB at full power
Tubes: 2 x 6DJ8 (ECC88), 2 x 12BH7, 2 x 274B, 2 x KR 300BXLS or 32B or AV 320B SL
Weight: 30 kg
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opinia @ highfidelity.pl
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