3DsoundSurge Reviews: Videologic DigiTheatre


	Mikael Hagén puts Videologic's DigiTheatre Dolby Digital 5.1 speaker system to the test

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DigiTheatre - Mikael Hagén - October 20, 1999

Detailed Overview

The DigiTheatre comes with 5 satellites, one subwoofer with built in amplifier, one AC-3 decoder with remote control, a SPDIF RCA phono cable, 9 pin DIN to 6 RCA phono cable and one dual RCA phono to dual RCA phono cable. If you choose to buy just the decoder you not get the dual RCA to dual RCA phono cables and of course not the satellites or subwoofer.

The two front satellites house a two way system with a 2 inch tweeter and a 4 inch woofer while each of the two rear satellites only has one 4 inch speaker driver and the center only a 3 inch driver. They all have the same power output of 7.5 W (RMS) and the frequency response is 180Hz-20Khz for all satellites except the center which has a frequency response of 140hz-20Khz. The subwoofer has 6.5 inch driver with a frequency response of 50 hz-200Hz and total power output of 25 W (RMS). Using our test CD shows that all the components deliver on their frequency response (at least the low-end as the high-end is a bit tougher to test).

The frequency response doesn’t mean the satellites never produce anything below the specified level or that the subwoofer never goes above the specified level. However, using the satellites as an example, the amplifier will attenuate the audio below the 180 Hz quite significantly, about 8dB lower in the case of sound at a 150 Hz frequency. As the frequency goes lower than 150 Hz, there starts to be a clear difference between the front left and right and rear and center satellites. If I feed a very low frequency sound to the front the subwoofer will take care of most of that but that’s not the case for the rear or center satellites. The reason for this is most likely that the decoder is always in small mode for the center and surround channels so the filtering away of low frequencies is already taken care of in the decoder. Feeding a very high frequency to the subwoofer would do the reverse and send most of that to the front channels. More details about what impact how the amplifier works later in the review.

The subwoofer/amplifier unit has an RCA phono input to each speaker and also an aux input. The Aux input is if you for some reason would have a need to connect a stereo source using a standard mini-jack cable. On the front of the amplifier unit you have master volume knob, on-off switch, input selector and speaker mode button

The master volume amplifies the signal you get from the digital decoder or other input source (e.g. soundcard). Since the subwoofer is usually placed on the floor you will not use this to change the volume during the movies or playing game but instead just set the maximum volume you want and use the DigiTheatre remote control for varying the volume.

The input selector button is used to choose between aux in or the 6 RCA phono inputs. When you have chosen aux in the stereo signal will be duplicated to the rear channels but the center will be dead. The subwoofer doesn't fire much in this mode either.

The speaker mode button (called DVD mode) is used to choose between stereo mode and AC-3 mode. In the stereo mode what's sent to rear and center speakers aren't used and the signal to the two front speakers are just duplicated to the rear. In DVD mode each satellite gets the signal you would expect. That is, what you send in to the front left will be only heard from the front left speaker, with the exception of frequencies below 180 Hz, which as mentioned above, are sent to the subwoofer. You will usually choose the AC-3 mode but when you play music in stereo you may want to hear the same music from the rear too.

The DigiTheatre decoder is not only a decoder but also a control box. For the AC-3 decoding (and Dolby Prologic/Surround) they use a Zoran DSP that many much more expensive AC-3 decoders use. Zoran’s chip, ZR38600 DSP to be exact, is also used in Cambridge Soundworks Desktop Theater 5.1 speaker system and I guess the DTT2500.

The decoder has both coaxial (RCA) and optical (TOSLINK) digital input, it also has two (left and right) analog RCA phono inputs to connect to an analog stereo/Dolby Surround source and of course a power input. For output it has a 9 pin DIN (don't confuse this with Live's Digital DIN as the Live use it’s DIN for digital not analog signals) and also separate front, center, subwoofer and surround mini jacks in case you use it with a speaker system that doesn't have RCA phono inputs.

When it comes to control the decoder offers you a range of settings and you can access them via a remote control or buttons on the decoder. To see what you're doing the decoder has a display window, which also has a small window that let you know how strong the signal is to each speaker at the moment. The decoder box control buttons includes a power button, mode button to step through the different menus, an enter button when you have chosen the speaker mode you want, an up and down button to chose the settings for each mode. The up and down button functions as a mute and test button as default. Changing the settings with the buttons on the decoder is tedious at best since you need to repeatable press the mode button to step through the different menus. Fortunately, VideoLogic included a remote control (see picture) where you have fast and convenient access to all the functions including increase or decrease the volume, power, test, mute, input (analog or digital), balance, delay, speaker mode, bass, surround, Pro Logic auto on and reset.

When you play test you will hear a hissing sound traveling from speaker to speaker that will let you know if you connected the speakers correctly and also help you to get the right speaker balance including the subwoofer. You can also adjust the delay time, that is the time lag between the front and center or surround speakers, of the center and/or surround speakers. If you're much closer to the rear or center than the front right and rear you can add some delay to the rear. By adjusting the delay time of the rear speakers you can obtain the feeling of presence.

The surround button allows you to change between Pro Logic and stereo. AC-3 is autodetected. If you choose stereo mode you will only hear stereo in the two front channels and not in the rear. Choosing stereo mode has no effect when AC-3 is detected, so it will therefore work only when playing stereo or Dolby Prologic content. You can choose Dolby Prologic on any analog or stereo source in which case you will often will hear some of the natural ambience in the music as surround sound.

The bass button is used to choose between large and small mode for the front left and right speaker. Dolby Digital decoders usually have a small and large speaker mode. In the large mode the satellites get all frequencies which can cover the entire audible range (20 Hz – 20,000 Hz), both for front and surround satellites. In addition to that they have a LFE (low frequency channel) but it doesn't mean they use it for all low frequencies, in fact many movies doesn't even use the LFE channel much. However the LFE track (the ".1") makes it possible to reproduce low bass effects with stunning impact (twice as loud as the other channels), so when it's used your subwoofer will really rumble.

The DigiTheatre decoder always has the rear and center speakers in small mode but offers the option of having the front in large mode. The reason to filter the low frequencies is if your satellites can't reproduce them well, e.g. without producing distortion. When you select large speaker mode for the front, the sub will be rather passive in most cases. This means that for music and especially for games I preferred the small speaker mode. For DVD movies the large speaker mode works quite well but you may still want small speaker mode to direct more of the low frequencies from the front satellites to the subwoofer.

If you will use the decoder with another speaker system where the front speakers are full frequency response speakers you should use the large mode as mentioned and if you have 5 full frequency speakers you may want to use another decoder. The reason VideoLogic doesn’t support full frequency for all speakers is that most only have 2 full frequency range speakers and Dolby demands higher license fees if you support that option.

Finally the speaker mode button allows you to change the output depending on your speaker configuration. You have the choice of just using the 2 front speakers, 2 front + center, 2 front + 2 rear and 2 front + center + 2 rear. I don’t see much use for the 2 front speakers or 2 front + center choice since it’s only useful when you don’t have any rear speakers. The option of 4 speakers with no center is useful if you intend to use it with another 4 speaker system that lacks a center channel, e.g. the VideoLogic’s Sirocco Crossfire.

The decoder will always expect it’s used with a subwoofer so you better have a 4-speaker system where you have a separate subwoofer input like the Sirocco Crossfire 4-speaker system or a separate subwoofer.

Back to the introduction

So on to the installation