Quad II Classic Monoblock Amplifier - The rebirth of a legend


Electronic light amplifiers reproduce the legendary design more than 60 years ago with nothing changed ... Quad II Classic success?


As a brand with a long history, many times the Quad has reprinted his old design by adding the word "Classic" on the new product name, Quad II Classic too. This is not a model or improvement of the Quad II amplifier serial dating from 1953, which is actually a remake identical. Circuit of the amplifier does not change anything compared to when it was producing more than half century, almost nothing changed except that some of the more advanced new components, a metal cage to protect the bulb is added, and the power cord with integrated switch. Other than those small details, the Quad II Classic is Quad II model of 60 years ago.

Design

Quad II, was 60 years ago or the new Classic version, there is a push-pull Class A monoblock design 15W RMS power per channel at 8Ω, with an input layer and an output layer. The input consists of two floor lamps pentode EF86 small, each lamp is against the separate a light output, but only one of the EF86 which receives light input signal.


First light, outside the light load output while at the same time load the second EF86 light with a portion of the output signal commutation or reduction of about 6dB. Therefore, the output signal of the second EF86 lights are similar but out of phase compared to the first signal light, and put together a complete signal when taken to the audio output transformer. This circuit design is called paraphrase, been widely used because it is two steps commutation and voltage gain (voltage) at the same time, thus keeping the circuit simple, limited distortion and reduce production costs, however, the theoretical error can arise in the process of signal coupling.

The output layer of the Quad II a power light pair KT66, are arranged according to the type of cathode coupled: both cathode and anode of the two balls are primary fight with audio output transformer, requires transformer design and winding very accurate, but in the fact that achievement is the feedback becomes more evenly than traditional way is connected to the grid of the lights with transformer sound. Thus, the Quad II provides sound with low distortion as Class A triode running, but it has high performance.
  
Power of Quad II is much simpler than today's single end triode amplifier. Quad II Classic used a GZ34 valve lights (while the first-generation Quad II tube GZ32). Power supply directly to the anode of the KT66 while for KT66 grid and anode of the EF86 through a choke and a small capacitor. Meanwhile, the main transformer also has an auxiliary power supply 6.3V AC for the audio ball, and 5V AC GZ34 lamp.

On the surface, this is a British-style amplifiers quite markedly, designed to carry minimize style (although the definition of this style, it was not until the early 1970s appear). Like other high-end products of the Quad, Quad II wiring completely by hand and enamel paint coating chassis gives the feel of a premium product.

Sound


Compared with modern light amplifier, the Quad II Classic is quite compact and not too much heat. Do not use the delay or relay so the bulbs start to heat up as soon as you turn on the power switch, though you should still amplifier to run for about 15 minutes before you start enjoying. Run the initial review process will take about a week before this amplifier's sound quality is really perfect.

Not natural Quad production goes to an amplifier has over 60 years of age, by its sound quality electronic tube amplifier that no less sweet modern day do not match. Quad II gives a nice mid range and full, very emotional especially with classical music and especially jazz. Disadvantages of Quad II bass is sometimes not treated explicitly as semiconductor amplifier with high-end, but the bass range is still very much alive and majestic, not drown even turned up high volume. Of course with a capacity not greater meaning Quad II is not an appropriate amplifier to hear the kind of music requires fast processing speed and strong as rock.

Negative balance is also a strong point of this amplifier, providing sound quality for different types of musical instruments, and even the same type of instrument. Not only alive and warm, Quad II also brought a sound space with considerable width, and generally sound quite stable across the frequency range, although the treble sometimes has been filled by a series of over- emotional attract all the attention of the listener. When paired with a genuine pair of speakers like the Quad ESL-989 - a pair of speakers with outstanding treble but medium range slightly dry, you will get an ideal sound quality on almost all aspects.

In 1996, Quad has released a commemorative Limited Edition version of the Quad II amplifier, but with distinctly different design than the first-generation model Quad II, and the results have proved to be not very convincing except with Quad brand fans. This shows that not everything more innovation is better. Coal technologies such as disk or electronic lamps continue to be many lovers, despite the popularity of the modern technology. By producing amplifiers Quad II Classic true like design was born from more than half a century ago, only some improvements in the quality of more expensive components, Quad firm to assert their traditional quality then and now has not changed and has been successful.

Conclusion

Quad II Classic is a range pre amp, sound warm, emotional and inspiring music. This is an amp that is probably half a century from now will still continue to attract many people.

Parameters
Output power: 15W
Frequency range: 10Hz - 20 kHz
Distortion: 0.08%
Impedance: 8 Ohm
Size: 315x165x120mm
Weight: 8.3 kg / subject


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