Digisynthetic, a Chinese brand that manufactures professional sound equipment and OEM DSPs, builds high-end power amplifiers, but at Asian prices. Curious, isn't it? Digisynthetic is a major manufacturer of professional sound equipment in China that, besides its own designs, develops custom OEM products for other brands, nothing new that we don't already know about Asian manufacturers. Digisynthetic, one of the big Asian manufacturers, is not known at all in Spain and is all Greek to us. Between the fact that we Europeans show no curiosity whatsoever about where or how 90% of the sound equipment we consume is made, and the fact that they don't go out of their way to explain themselves either, we work from preconceived ideas and stereotypes, which is dangerous. As a counterpoint to the preconception about all Asian products, there is this power amp tested in this article, the Digisynthetic DSP 1200.

A DSP and a Power Amp Hand in Hand
Since their commercial debut in the audio market, DSPs have been a revolution similar to the one caused by the arrival of silicon transistors in electronics in the mid-20th century. DSPs offer greater capacity to work on sound, faster, in far less space, and cheaper than their analog circuit equivalents, undoubtedly crushing arguments. Their development is owed to the military, in the analysis of signals picked up by radars and by the sonars of submarines and ships.

What this test deals with is a hybrid development between analog and digital: a conventional power amp together with a DSP processor, a pairing that, although not new, is little known. These two elements under the same chassis form an especially useful combination, since they can integrate the functions of an active crossover and amplification in a single block, and therefore without cables.

The first surprise of this amplifier is its weight, 31 kilos, a figure that is quite unusual for an amplifier with 300 watts at 8 ohms, a weight more normal in much more powerful amps. All this weight can have only one direct culprit, the power supply and more specifically the transformer, or rather the two transformers this amp uses, both of more than considerable size.

Design Philosophy
The build philosophy and the materials used run counter to what we're used to seeing in Asian devices, which are smaller and lighter, whether under their own name or sold under other brands. Staying with the transformer, we mustn't forget that copper, its main raw material, is a scarce and therefore expensive mineral, but on top of that high cost there's the added expense of transporting it, usually by ship, where the weight of what is carried substantially increases the price. So taking copper from, say, Chile, one of the main producers, to China where it is manufactured, and then, once it has become a transformer and part of a device, putting it on another ship bound for Europe, America, Australia, and so on, becomes an added cost that significantly increases the final price of the device, easily pricing it out of the market.

The DSP1200 also differs from the usual Asian approach in its design and manufacturing philosophy, which clearly recalls the Japanese way of building high-end equipment. The electronic components of this amp are not the usual SMD parts; except for the DSP board, they are standard size, though inserted into the boards in a manner similar to SMD. It is a way of manufacturing more typical of high-end, short-run Japanese brands, because of its higher quality but also higher assembly cost.

Looking Inside
With the top cover removed, what stands out most at first glance are the two enormous transformers and a heat sink that takes up 50% of the amp, under which the amplification electronics sit. Between the power supply and the heat sink there is a metal dividing plate, which besides giving rigidity to the chassis serves as a mount for four fans that create an airflow that cools the output power transistors by passing over the heat sink they're attached to. Without that heat evacuation their lifespan would be short.

The arrangement of these fans, centered inside the chassis, manages to reduce ventilation noise, which is already very low to begin with.

At the back and under the heat sink are the amp's components: transistors, resistors, capacitors, and so on. To reach them you have to remove the unit's bottom cover, which once opened reveals the main board where all the components are laid out.
Especially obvious because of their larger size are the output transistors. Little can be known about them, since the manufacturer has deliberately erased their part numbers, but it's to be expected that they are identified in the service manual for maintenance purposes. What is most surprising about them, though, is their number: while most amps of this power usually use two or four power transistors per channel, Digisynthetic fits 10, increasing the number in higher-power models, where it reaches twelve per channel.

Control Software
The control software is quite simple. Once the amp is connected to the computer by a cable and with the program the manufacturer supplies, you can control EQ, levels, and phase, among other things.
The program's main screen offers signal processing across several options. The order of the processing cannot be changed and is as described below: overall gain, EQ, crossover filter, delay, phase control, and level limiter.

The EQ is made up of three points of action, each with gain of plus or minus 12 dB and a bell curve, or “Q,” of variable width, from the narrowest at a value of 128 to the widest at 3. The next control is the crossover, which works with a bank of fixed Butterworth, Linkwitz-Riley, and Bessel filter curves, with an adjustable cutoff frequency, in two options, high-pass and low-pass. The result of the frequency split is shown on screen with a simple but effective graph.

For the delay function, you can choose distance values in meters, up to 2,400 meters, or time up to 7 seconds, more than enough for any sound reinforcement position. After it comes the phase control, with only two options, 0º and 180º. Finally there is a signal limiter, with the three usual controls of hold, attack, release, and level, the latter with values from +3 dB to -61dB.

This signal-processing feature set is geared toward the typical work of a crossover, and at first it doesn't seem very suitable as a replacement for a master EQ on the stereo output, a place where many engineers still prefer the conventional, time-honored analog third-octave graphic EQ.

Features
The DSP processor sits behind the amp's gain controls and is an in-house Digisynthetic design, as could hardly be otherwise. It has digital conversion specs of 48 kHz sampling rate and 24-bit quantization.

What is missing is a digital audio input straight into the DSP. That would make it possible, in digital gear environments, which are increasingly common, to avoid breaking the digital chain of the sound. This option is common in DSP circuits, so it wouldn't be a major technological or financial effort for the manufacturer, and it would be a substantial improvement in the unit's features.

As for amplification, the manufacturer cites a power of 300 watts per channel at 8 ohms, but without a measurement with the proper equipment to confirm it, the power of this amplifier sounds higher than those values, judging by ear against other units of similar power. Two circumstances lead to this thought: it has a power supply whose delivery characteristics are far above what that power requires, and second, the output transistors are, by quantity, better suited to much higher powers, more than double, compared with the average of models from other brands.

Conclusion and Sound
The impressions this power amp conveyed throughout the test were very positive; the sound was exceptionally good, with spectacular dynamics and clarity. You could notice the power supply's energy reserves, which made powerful sounds like a kick drum hit, or the lowest notes of a bass, reproduced faithfully, without choking and without masking other instruments with softer registers.

On the other hand, the circuitry and the array of power transistors, in quantity and quality, manage to keep control of the signal, able to recover quickly after an increase in energy to cover a signal peak and follow the waveform of the signal being amplified. Dynamics is another area of great quality thanks to a slew rate of 20 volts per 1 microsecond and equal capacity for the opposite job: coming back down at the same rate.

The DSP's work is correct and of good quality, which is normal by now for any minimally professional DSP. The surprise would be the opposite.

A peculiar product, without a doubt, given what we're used to from Asia: price-slashing devices whose quality is always questioned. Good gear, without question, on par with any other high-end brand.