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DEQX - Digital EQ and Xover

Digital crossover firm DEQX was the last and simply amazing audio component, which fully cocked me in the direction of separate monitoring of PA. Moreover, even in the 80s was buried a full-fledged scheme of multi-band amplification and still not a single decent studio monitor with a digital crossover was manufactured ever since, exception is the JMF and Stage Accompany. Something similar is trying to portray Quested, Dynaudio, Clein & Hummel, but it is ineffective because dynamic drivers and amplifiers are not of excellent quality. Now is quite clear that an even middle static digital processor for professional audio seems tatally ineffective. Yes, they provide the digital divide of audio lanes, but the steepness of the cut is not higher than in the studio monitors, while at the interfaces of the drivers emerge strong of frequency and phase distortions which those crossovers cannot set off. Conventional crossovers can equalize the volume levels of the speakers and the time delays, but their measurements require special equipment or software. Partially the amplitude-frequency characteristic of sound drivers is aligned, but with 5-10 sliders on the equalizer, more of that cannot be done. Moreover, none of the processors is able to make such measurements and corrections in automatic mode. And speaking about the correction of room acoustics, Ishould keep quiet.

For that kind of work now is only capable – DEQX device! I stumbled on it, as on all first-class components of Class Ultimate Studio, quite by accident. At first I could not believe in the claimed capabilities of the processor, because at the market of professional audio equipment there was nothing even close to it. Product price was impressive; it did not much differ from the prices of processors of other companies.

Introduction to a device was held in Moscow office of the official dealer - the company's true stereo www.stereopravda.ru . Ironically, the three-way system speaker DMT-100 Proclaim Audioworks that I have been listening had dynamic drivers of company Eton, established in spherical shells. These drivers also use in their products company Adam. Those drivers also earned a deserved reputation among domestic sound engineers who very often built in these drivers in their studio monitors. Acoustics has a 12 "long tail and 5" midrange driver. Tweeter is a soft dome shaped. System was connected by the RA scheme to multi-channel THX amplifier.

The processor is configured through any PC with a USB or RS-232. If you do not particularly go into all the features of this unit, controlling is very simple: the user does not need anything more than just a job section points between the speakers. Interface of programme Setup is relatively simple. I did not do print screens of all windows applications, except amplitude-frequency characteristics, which is more important and it is present entirely. More information about the work with on crossover can be found at this link http://www.6moons.com/audioreviews/deqx/deqx.html" target="blank"> and trough the user’s manual at the manufacturer's website.

Measurement and correction of the AU made in five steps:

1) A minimum frequency of the measurements is set to prevent the burnout of the tweeters. Next, select the number of steps, measurements and pulse of moving sinus. The more these values, the more accurate the resulting graphs are obtained. Then, given the coordinates of the location of the measuring microphone and the program produces a measurement of the frequency bands AC. After that on-screen form will pop charts of AFR loudspeakers. The procedure is repeated for the second channel. Large irregularities are shown at the frequencies below 1 kHz due to the low-frequency location of the LF driver that is close to the floor. Generally, such measurements should be conducted in an anechoic chamber.

2) At the control line of frequency line with double-click the specified point shows the section bars and the steepness of the filter. The graph shows the total response of both channels. At the same time program immediately calculates the overall frequency response at the section. If there are tangible peaks or dips of the frequency response, it must be by trial and error to set the slider to the optimum position. For some reason the processor does not allow to set the steepness of the filter of 300 dB / octave at frequencies below 600 Hz. With the steepness of the cutoff of 250 dB / octave at 300 Hz were observed unevenness in 5 dB. A company representative said it was not very good, although the processor can correct them. Limits of adjustment in response device are within +6, -10 dB per octave. Minimal irregularity in the bass turned out at the cutoff frequency of 70 dB / oct. Described process of adjustment is not so simple and requires minimum one day just to find the optimal values. Mid-frequency maximum slope of cut does not cause significant irregularities. Note that the MF and HF driver in the most sensitive area of human hearing are sounding joint width of approximately 700 Hz at the fall ov signal strength of 300 dB / Oct. Now imagine the zone of joined sound within other crossovers at the 48dB/Oct! And this is the most critical region for the human ear! For comparison, the response of a typical analog tri-band crossover :amplitude-frequency caracteristic tipicall for analog three-way crossovers skretnice, which can be found in professional audio and studio monitors.

3) On the next image we should delineate the blue rectangle of the AFC that has to take a correction, if the variant that program proposed is not optimal. The final schedule is also changing in real time. AFC is corrected by lowering the overall level of amplitude, relative to the very low-sensitivity band.

4) The fourth tab shows the estimated counter-response of each speaker two channels.

5) Now you only have to store the settings to a file on your hard disk or directly upload them to the processor. At this stage it is possible to write a few tweaks, appointed to 4-button remote control. Usually there are limited only by-pass mode, in which only crossovers, and the By-pass + Corrective settings, which include corrective counter-response, phase and time delay correction pulse characteristics of drivers. This will simulate the sound of the AU through instant switching between presets to compare results before and after correction. At this stage, you can set the cutoff frequency and frequency range on the border of ultra and infrasound.

In general, the effect of application of this crossover is equivalent to changing the speaker! And that on the best monitor speakers that are connected to the pure RA scheme! Now, the sound of monitor drivers truly becomes monitor! According to subjective feelings, AFC really reached a perfect straight line. We were pleased with the normalization of extremely bright MF and we are even much more surprised with stereo panorama and general composure of sound. Before this, it sounded like the sound moved from the entire surface of the front walls of the room, and then suddenly, stood at the installation site of the loudspeakers. It became clear where is right, where is left and the location of the speakers can be easily determined, even with your eyes shut. Then I was finally convinced of the pernicious influence of AC phase and time delays. The effect of what I heard was so strong that I even gave up demonstration of show room correction system modes. Why should I do that? Let us not forget that in a room where Ultimate Studio Acoustics will be installed, that is not necessary because such a room is almost anechoic chamber.

We should not forget about another important detail, especially in the framework of this project. This processor is available with digital outputs that will use first-class external DAC for each frequency band. There is no special term for this connection method, so I called him a multiband transformation. Just imagine how would sound monitors or TAD Stage Accompany with DAC DCS or MSB, corrected with DEQX!?

The description of this apparatus I can complete with a few lines ... With the help of the DEQX, correction is really possible to get a monitor and surround sound of any passive speaker or even cheap speakers. But it cannot fix low-quality sound and distortion of drivers and amplifiers. Base sound quality is produced by the system components and the Maximum effectiveness and relevance of such equipment is only available with the Ultimate Studio class.

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