iXBT Labs - Computer Hardware in Detail






External DD5.1/DTS Decoder Jazz Speakers DE-005

With the wide spread of multichannel sound cards with a digital interface and wider support of modern achievements in the field of digital audio in software, a user encounters a traditional problem: how to use all these advantages without spending too much money.

Computer sets of speakers with a built-in decoder (for example, from Creative, Jazz Speakers, Altec Lansing) are often not cheap and quite compromise solutions, which are, at the same time, a good choice for people lacking for time or will to find any hard construction and design methods. On the other hand, high quality wooden sets are too expensive. Those that have acceptable prices have neither 5.1 decoder, nor any DAC (F&D IHOO 5.1, Jazz Speakers 9906, the latter is usually supplied with a separate decoder DE-006).

That is why we are turning to an external decoder DD5.1/DTS. What are its advantages?

  1. allows choosing a set of a high quality active 5.1 acoustic system (or usage of a Hi-Fi audio complex which you might use as such system);
  2. allows choosing among 5.1 sound cards (in order to improve the sound at the expense of refusing the built-in codecs and adding a capability of decoding DTS standard);
  3. allows a normal playback of a 5.1 track in movies on a 4-channel card with a digital output (Live!, Vortex2, Yamaha 7x4).

Today we want to tell you about one of such devices - an external Dolby Digital decoder which is a DTS decoder at the same time. Apart from decoding DD5.1/DTS soundtracks in DVD movies, the DE-005 can be used for playing usual Stereo or Dolby Pro Logic in digital mode, as well as for distribution of a stereo signal to 5.1 speakers due to an integrated effect-processor. Such capabilities justify quite a high price of the device (around $200).

We have decided to compare this solution in quality and in handling convenience with analog versions with regard to Pro Logic and Dolby Digital 5.1 in software DVD players, as well as in the drivers of Live! 5.1 sound cards.

Appearance and Functionality

The complete set includes:

  • Decoder
  • Power Supply Unit
  • Remote Control
  • User's Manual
  • Coaxial Cable (RCA - RCA)
  • Cable (R&L RCA - Stereo Mini Jack)

Apart from logotypes "Dolby Digital" and "Digital DTS Surround", in the center of the front panel there is a large LED display conveying the information on all modes of the decoder.

On the rear panel there are 6 linear-outs, linear-in 1 (stereo RCA), another linear-in (stereo mini jack), digital optical and coaxial inputs.

Remote Control

We have already seen such remote control in the Jazz Speakers ROCCO 5.1 Digital Audio System. The device measures 60 X 15 X 160 mm. There are some duplicate buttons (for those which are on the front panel of the decoder): Power, Mute, Mode, Line, Optical, Coaxial, Volume. Besides, with one button you can choose the effect-processor mode (Theater, Hall, Stadium) and decoder's modes (DD5.1, Pro Logic, Stereo, DTS). A separate adjustment of the channels' volume level is implemented with the Trim button. The Test button will help you check whether you have connected the speakers the right way by an alternate transmitting of a noise signal. With the SPCFG button the bandwidth for satellites (the distribution of low frequencies among other speakers apart from a subwoofer) is adjusted in decoding modes Dolby Digital, DTS, Pro Logic. The C_Delay and S_Delay buttons are also intended only for DD 5.1 and Pro Logic modes. Here you can set the delay time for a central and rear channels: S_Delay - from 0 to 15 ms in 5 ms increments, and for C_Delay it is from 0 to 5 ms in 1 ms steps. In both cases the default value is 0 ms.

It should be noted that as far as the settings are concerned the software versions of 5.1 decoders (soft DVD player + 5.1-channel card) have a separate volume control of channels in the card's mixer at best. Is it worth blaming such cards with WinDVD/PowerDVD in one box at only $20 and to praise, at the same time, much more expensive hardware decoders? I don't think so, it's a normal situation.


The decoder has plenty of ways to be connected. There are two analog inputs (stereo mini jack and RCA) and two digital ones (coaxial, optical). The decoder has got three analog outputs, a stereo mini jack (FL/FR, RL/RR, CEN/SUB) and a 9-pin miniDIN (G9) for connecting acoustic systems of the same manufacturer.

Life Is Not Easy

4/5.1-channel sound card owners who want to use the multichannel sound in games will have some problems: in usual PCM stereo mode (in digital mode) they will get only stereo.

As for the Live!/Live!5.1 sound cards, the situation is even worse: the decoder refuses to recognize usual stereo in digital mode (PCM signal on S/PDIF), even though Dolby Digital and DTS signal are recognized without any problems (we have already spoken about it in the article on the Jazz Speakers ROCCO 5.1). It is rumoured that it is the fixed sampling frequency of 48 KHz that should be blamed. However, other sound cards (on YMF7X4, FM801, AU8830 chips) worked flawlessly at this frequency.

My colleague Mikael from the 3DSoundSurge site conducted more thorough experiments. Among ten sound cards with Jazz decoders in PCM mode, except all the models of the Live! series, the Philips Acoustic Edge and Terratec DMX Xfire also refused to work. The signal from the latter suited the DE-005 with the VxD drivers and didn't please it with the WDM ones.

But I can't say that Philips knows nothing about their own standard (note that the abbreviation means Sony/Philips Digital Interface Format). The problem seems to be lying not in the electric parameters of a signal but in the data transferred. As you know, according to the S/PDIF standard (IEC-958) apart from usual data the digital flow contains also service data. In a 32-bit subframe the bits are distributed the following way:

Bits Values
sync preamble
coded channel's name
PCM or data, 16-20 bits
error flag
multichannel data transfer flag
parity flag

Each block carries a subcode of data copyprotection (SCMS). Besides, a 30th bit informs the decoder on the data coming. So, it seems that the decoder doesn't like something in the signal received. Maybe it dislikes the absence (or presence, on the contrary) of a data digital copying protection code.

I can give a piece of advice to the owners of 4-channel cards the decoder is working with: you should apply a signal to the front/DVD in digital mode, and connect the rear channel in analog mode. Or you can connect the cable from the rear to the G9 connector (SR/SL contacts on the right). But if you are embarrassed you can make a Y-shaped connector with a 2-position switch for two pairs of contacts allowing to direct the signal from the card's rear to the decoder's rear.


We continue to scrutinize the card with opening its case. Having passed a simple electric circuit consisting of a pair of resistors and a capacitor, the signal from the S/PDIF connector gets to the CS4226 KQ audio codec from Crystal Semiconductor.

Two 20-bit ADCs and six 20-bit DACs. All the converters are of sigma-delta type. Besides, the chip includes a digital receiver which receives a PCM signal within the sampling frequency range from 30 to 50 KHz, as well as AC-3/MPEG signal in order to be installed together with a hardware decoder. The specified characteristics are not that bad:

Dynamic Range (DR) 95 dB (98 dB A)
Total Harmonic Distortions (THD) 0.003%
Total Harmonic Distortions + Noise (THD+N) -88 dB
Crosstalk -90 dB
Frequency Range (FR)
10 Hz - 20 KHz
+/-01 Hz

So, in case of a digital multichannel signal it goes to the hardware Dolby Pro Logic/Dolby Digital/MPEG2 stereo/DTS decoder CS4926 04 CL from Crystal Semiconductor. The decoder has a 24-bit processor controlled by a microcontroller AT27C0 from Atmel.

I should also note that inside the DE-005 case there is a power supply stabilizer which gets warm very fast. Tiny ventilation holes and a large heatsink don't help it much, and in 5 minutes the decoder becomes very hot. A power supply track has some advantages such as 4 smoothing 1000 mF capacitors and absence of the noise and pickups caused by power supply in output channels.


Of course, any opinion is subjective, but due to the high professionalism of the tester it is possible to gain the maximum benefit from his point of view :)


We applied the signal from the Aureal SQ Digital sound card in digital mode and compared its sound with the Live! Value and Live! Player 5.1 cards. With the active acoustic system F&D IHOO 5.1 we played the compositions of all genres: from classical compositions to pop songs, from mp3 128 Kbit to proprietary CD-DAs. Don't be surprised: mp3 compositions with a low bitrate is not that bad test material. Since the signal initially suffers from a lossy compression, any further conversion worsens the impression sharply.

The DE-005 sound is similar to that one of the Santa Cruz (if you remember, there are also 20-bit codecs from CS). As compared with many 18-bit codecs of sound cards (Sigmatel, Wolfson) sounding flatly and crumpled, 20-bit codecs from Crystal have very pleasant and truly sounding highs and some kind of transparency (though they do not have the announced bit capacity, since they are in fact 1-bit delta-sigma). Apparently, the tricks of a good regenerative digital filter give an explanation for it. At this site I have come across a Live! remake in which a rated Sigmatel codec was replaced by a similar one from Crystal Semiconductor. Due to the single standard of AC'97 such procedure succeeded, and the author said that the characteristics became even better.

Before starting the tests I thought that one would feel the difference in sound as compared with mainstream sound cards only on expensive systems, but I was surprised at the difference noticed on a non-expensive wooden acoustic system F&D IHOO 5.1. The sound was much better than that of the Santa Cruz. Apparently, the KQ series of CS is of a higher quality (the Santa had JQs with 14-bit effective characteristics). Plus, a 4 times bigger codec intended for Hi-Fi consumer equipment has also contributed. But taking into consideration the price of the DE-005 I can't say that the sound was exclusively perfect. I would rather say that it corresponds to the expected level.


This decoder can reproduce a sound track of DVD movies in Dolby Digital 5.1 and DTS formats. In this case it is not necessary to have a computer. The signal can be transmitted in digital mode from a stationary DVD player, and from a game console Sony PS2. The computer requires either a soft DVD player (WinDVD, PowerDVD) and a sound card with a digital interface (for movies any card can be taken, including the Live!), or a hardware MPEG2 video decoder. Those who like MPEG-4 movies, can enable the forced decoding Dolby Pro Logic on the DE-005 together with stereo. (Attention! MP3 tracks in MPEG4 movies are converted into PCM stereo, and this is a red light for Live! owners) For MPEG-4 with multichannel sound I would recommend a DivX player BSPlayer, which allows you to enable the mode of through passage of AC3 stream to the S/PDIF output of the sound card (besides, there is a convenient toddler called custom pan-scan for adjusting a widescreen picture).

The quality in movies was first tested on a cheap home theater (the JPW speakers and Onkyo TX-DS484 receiver) via a 5.1 analog receiver input and compared with the decoding quality obtained from the receiver. We have listened to movies and trailers with sound tracks in Dolby Pro Logic, Dolby Digital, DTS formats. In my opinion, the DE-005 sounds much better than a 5.1-channel Live! Player 5.1 sound card. But still, the quality of Jazz's decoder is worse than that of a receiver with 24/96 converters which price is, though, three times higher. As for the disadvantages, I can say that the timbre is a bit flat, and the sound is not very natural on the whole. With a decrease of the class of the amplifying and reproducing equipment these differences become unnoticeable. And for an upgrade of a budget DD ready receiver or a decoder with only Pro Logic onboard the DD/DTS decoder will be a good choice.

When comparing with 5.1 sound cards the DE-005 is undoubtedly ahead. Such features as a finer adjustment for the definite speakers, better sound, the remote control are the highs of the decoder. The drawback is only its price (around $200).


It is difficult to use the decoder for games due to a lack of a multichannel analog or digital input. Another obstacle is incompatibility with the Live! sound cards in PCM mode. But if you don't need a multichannel sound you will be able to achieve a compromise having connected the rear channel to an analog output, and the front speakers' quality won't disappoint you.


I can't consider the decoder as a godsend but it is still a quite interesting pretender for a place in a computer or audio-video complex or in a home theater of the low end.

Highs of the Jazz Speakers DE-005:

  • good sound of the 20-bit converters;
  • 5.1 Dolby Pro Logic, Dolby Digital, DTS formats support;
  • a great deal of settings can be made with the remote control;
  • small dimensions;
  • informative indicator display;
  • inputs of all formats: analog stereo mini jack and RCA, digital optical and coaxial ones.

Lows of the Jazz Speakers DE-005:

  • digital incompatibility with the Live! cards in PCM mode;
  • overheated case;
  • bulky remote control.

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