Product Review - Onkyo TX-DS595 Surround Sound Receiver with Dolby Pro Logic II - May, 2001

John E. Johnson, Jr


Power Output: 75 Watts RMS per Channel (x 5) into 8 Ohms

MFR: 10 Hz - 100 kHz  + 1 dB -  3 dB

THD: 0.08%

Preamp Input Impedance: 50 k Ohms

Features: AM/FM Tuner; 96/24 DACs on all Channels; Four Digital Inputs (Two Optical, Two Coaxial); Four S-Video Inputs; Two S-Video Outputs; 5.1 Analog Input Set; DD, DTS, Pro Logic II

Size: 6 7/8" H x 17 1/8" W x 17" D

Weight: 25 Pounds

MSRP: $599 USA    


Onkyo USA, 


For the past several years, Dolby Pro Logic has been less and less important due to the emergence of Dolby Digital and DTS, not to mention the new DVD-Audio and SACD formats. The problem is that there are billions of two-channel CDs out there, along with two-channel TV and radio. Dolby has solved this with the release of Pro Logic II, which takes two-channel recordings and converts them to 5.1. This format, unlike old Pro Logic, creates full-range stereo in the rear. Although DD and DTS are discrete 5.1, Pro Logic II synthesizes the stereo in the rear. Of course, discrete channels are best, but Pro Logic II is a real shocker as to just how good a job mathematical algorithms can do with two channels to start with.

The rush to be the first out with Pro Logic II in the receivers is on, and Onkyo is certainly a leader. Their new TX-DS595, reviewed here, has Pro Logic II, a full set of Pre-Ins, and 24/96 DACs on all channels, for the very affordable price of $599.

Take a Look

The front panel controls are very simple, and in fact, I found them among the easiest to use of any receiver so far. From the left, are the On/Off push button, Standby Switch, then the input selector buttons, FM tuner buttons, A/B speaker selector, and Mode Control Rotary Dial. Using the rotary mode dial is very intuitive and easy to scroll though all the DSP modes.

The rear panel (photo shown below) is simple too, mostly because it is a modest priced receiver. Four digital inputs (Coaxial and Optical Toslink, programmable for any input you wish) are enough for most situations, assuming you would connect at least one DVD player and perhaps the digital audio output from your satellite receiver. All video connections in and out have S-Video. There is a set of 5.1 analog inputs (close-up photo shown below) for DVD-A, but there is no set of pre-outs for use with an outboard power amplifier. You can't have everything for $599.

Since each input might have a different inherent volume, Onkyo put "IntelliVolume" into their receivers. It lets you preset a specific volume setting on the volume control for each input, so you will have the same relative volume when changing inputs. Also, the "Maximum Volume" and "Power On Volume" lets you set the maximum volume setting (for curious kids) and volume that will be enabled when the 595 is first turned on. Both of these features will protect your speakers. Some receivers use the "0 dB" format to represent full output, and where such settings as - 10 dB being lower volume, but that is confusing to some consumers. Onkyo uses 1 - 79 as the relative volume. This is the better method, in my opinion, rather than having increasingly negative numbers for lower volume levels.

Another nice and easy to understand feature is the delay. As you know, surround sound is compounded by the problem of sitting at unequal distances from five different speakers. Often, there are delay settings in milliseconds (ms), which can be confusing. The 595 lets you set this up merely by specifying how many feet or meters away you are sitting from the mains, center, and rears. I like this very much.

The 595 AM/FM tuner operates pretty much like they have for the past few years. I have no particular comments on the quality of this unit. Scanning for stations to put into memory is not intuitive though. You need to press the arrow key for about a half second and then it will scan forward or backward until it finds a station. 

The remote control for the 595 is nicely laid out (photo shown below) with buttons of different shapes for tactile identification in the dark. It is not backlit. The complaint I have about this programmable remote -  and most receiver remotes for that matter - is that the basic receiver functions are set aside in order to accommodate the functions of other components you have in your system (DVD player, CD, Cable TV, Satellite, etc.) In particular, there should be direct volume controls for all the channels rather than just a main volume control. Although there is a channel volume setup control in menus, most movies I watch could use a little fine tuning in the volume department between front and rear, or sometimes, the center vs. the front main left/right channels. The subwoofer volume should also be adjustable without having to go through menus. All it would take is three dedicated buttons (besides the main volume control): one for center channel volume, one for rear left/right, and one for the subwoofer. Left vs. right could remain in the menus. On the 595, you have to press RCVR, then CH SEL (Channel Select), then scroll through to the channel you want to adjust (i.e., center or rear), then adjust the volume of that channel. Older receivers used to have a set of buttons specifically for the center and rear, with one button for volume up and one button for volume down on each of the channels. That is something which we should still have on modern remotes, but we don't. I am not picking on Onkyo about this, other than the fact I am reviewing an Onkyo receiver here. It is something almost universal in remote controls right now. At some point, our editors will design a Secrets remote control, using information we get from our readers, and then we will license it to whichever manufacturers want to have it, if any.

The Sound

As low-priced receivers go, this one sounds a little better than average. Onkyo would probably tell you about their WRAT (Wide Range Amplifier Technology), which includes low negative feedback and a high bandwidth. Various mass market manufacturers emphasize different things in their products. Onkyo spends more of its dollars on the power supply, as evidenced by the relatively large power supply capacitors I saw inside the chassis. This is a good thing for the 595 since there are no pre-outs for use with outboard power amplifiers. On the other hand, 75 watts per channel really is not enough for the kinds of digital surround sound tracks we have these days, and if you really like action movies and are just starting to set up your home theater, you should probably step up to one of Onkyo's larger receivers that has pre-outs for all channels.

Dolby Pro Logic II (PL-II) may actually turn out to be as popular as Dolby Digital. PL-II takes a standard two-channel stereo signal -  and this can include CDs, TV, FM Radio, etc. - and synthesizes full range stereo in the rear. My listening experience with this so far - using the 595 - suggests that it is a spectacular addition to the flexibility we have for using our home theater audio systems with our CD collections. I have never been a fan of the DSP modes, such as Stadium, Jazz Club, etc., that are present on all modern receivers, the 595 included. The artificial sound that they produce is much less enjoyable than just leaving the receiver set on plain old stereo. PL-II is basically a DSP mode too, but its algorithms are much more sophisticated, approaching the discrete 5.1 channels of DD and DTS.

Pro Logic II adds not only some stereo to the rear, but some reverberation too. The reverb is something I have never cared for in DSP, but it is not nearly as intense as it is in some conventional DSP modes. In any case, it is truly remarkable how good Pro Logic II really sounds. Of course, it is not like true discrete 5.1, but it is very enjoyable, and brings our CD collections closer to digital surround than ever before. It is also useful with FM stereo and TV stereo, but remember than the phase of the stereo signal and stereo blend (some radio broadcasters seem to like blending the stereo to make it reach farther in its transmission, i.e., a larger audience), and this will affect Pro Logic II just as much as it does regular Pro Logic. It will also work nicely with old stereo movies on tape or laserdisc, whether they are programmed for surround sound or not. Don't expect miracles, but do expect a new sound to enjoy. It is a big, big step up from the old DSP modes.


Onkyo advertises a large bandwidth ( - 3 dB at 100 kHz) as part of their marketing packages. Indeed, on the bench, I measured the - 3 dB response right at 100 kHz (in Direct Mode only, bypassing digital processing). At last, an advertising spec that is right on the money and not exaggerated. The square wave (10 kHz, 10 Volts) shows a nice smooth waveform with no ringing (photo at right). A 100 kHz bandwidth means very little to no phase shift in the audible band (20 Hz  - 20 kHz), so that is good. Much better in fact than the typical receiver in this price range. Nice to see real improvement in receiver design over the years.

Although the consumer spec says 75 watts per channel, the details are not given, i.e., with how many channels operating, and if it is full spectrum or at 1 kHz. I obtained a factory spec sheet that says the 75 watt power output for each channel is from 20 Hz  - 20 kHz. The power rating is OK, but remember, there are no pre-outs, so if you find it is not delivering the power you need with your speakers, you can't connect an outboard power amplifier. Remember that an "XX" watt per channel mass market receiver is much different than an outboard five-channel amplifier of the same rating. Outboard power amplifiers, in general, have much larger power supplies than mass market receivers of the same "watts rating", and such power supplies will sustain high current demands during intense audio movie scenes that last several seconds, as opposed to only being able to deliver those watts for a few milliseconds before going into clipping. The 595 is rated into 4 Ohms, but as with most lower priced receivers, you should stay with 8 Ohm speakers, and a sensitivity of 91 dB/w/m or greater, if possible. This will give you the best performance.


In its price class, the Onkyo TX-DS595 receiver is a standout. It has high bandwidth for lower phase shift, and gives you the newest and greatest of Dolby's achievements, Pro Logic II. For a small home theater, and where you have a large collection of conventional CDs, this is just the ticket for real enjoyment.


-  John E. Johnson, Jr. -

Manufacturer (Dolby) Response:

DSP modes usually mean a process whereby a form of room modeling is layered on top of the sound. The DSP creates the room reflections and reverb of the venue. These signals are added to the original recording, and were not present in originally.

PLII, like PL before it (and Logic 7) are performed in DSP circuit devices, but they are not "DSP" modes, per se. These algorithms create no reflections or reverb. What you hear are only sounds that were in the original source. The decoder can extract them and manipulate them, but never create them as in DSP modes. I would add that PLII (and PL) started life as analog circuits: VCAs and op-amps. These things cannot create the kinds of DSP effects that require the number crunching of DSP chips. Simpler is better!

So, we don't consider PLII a DSP mode at all. That has such a negative connotation to us purists.

Let me know if I've only confused things!

Best regards,

Roger Dressler
Director, Technology Strategy
Dolby Laboratories

[email protected]

Editor: You have not confused things. You have enlightened us! Thanks for the clarification.

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Copyright 2001 Secrets of Home Theater & High Fidelity
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