ZALMAN Theatre 6 (ZM-RS6F) Review: First 5.1 Headphones from the Cooler Maker

Today we are going to take a closer look at a new product from ZALMAN: a nice headphone set, which will undoubtedly enjoy a warm welcome in the gaming community. Find out more about this solution in our detailed review!

by Sergey Samarin
06/09/2004 | 03:54 PM

The market of computer hardware took its current shape quite a long time ago and we can easily enumerate the names of manufacturers of this or that type of equipment. On the other hand, each growing company expresses a strong desire to venture into a new segment of the PC market.


The desire alone is not enough, though, as it is also necessary to offer something exciting and special, so that the potential customer would recognize the new product in the computer shop. Zalman, a company well-known to many PC users, has chosen exactly this scenario of conquering a market, quite alien to it before.

Zalman is a name strongly associated with coolers for CPUs and graphics cards, with power supply units and system cases. So when I heard this company to have entered the market of PC multimedia devices, I was really astonished. Zalman started its activities in the field by releasing the external multi-channel ZM-RSSC audio card, the ZM-RSA microphone amplifier, and the curious ZM-RS6F headphones.

The last product mentioned will actually be the main character of this review.

The device is waiting for its buyer in this original packaging

First of all, let’s take a look at the specification of the device. This information can be found right on the package of the headphones.




Product name

Theatre 6

Model number


Type of dynamic heads

Electro Dynamic Round Type Micro Speaker

Frequencies range

50 – 20,000Hz

Sound pressure

89dB +/-3dB at 50mW


16Ohm at 1kHz

Nominal power


Maximum power



316.8g (without packaging)


Straight, triple entry 300cm


3 headphone mini-jacks



I’d like to draw your attention to the low input resistance (impedance), which is only 16 Ohms in the ZM-RS6F. In practice, this is a warning sign to you with respect to the volume level of the audio source – be careful when raising the volume control of the amplifier to the maximum. For note: the impedance typically lies in a range of 32 Ohms to 120 Ohms for high-quality headphones with an open acoustic enclosure (for example, 120 Ohms for the Sennheiser HD 590 and 32 Ohms for the Technics RP-F10). On the other hand, it’s clear even from the specification that the reviewed headphones are no Hi-Fi: the declared range of reproduced frequencies (50 – 20,000Hz) won’t impress an audiophile.

The manufacturer doesn’t say anything about the sensitivity of the headphones, but declares their sound pressure level, a rare item in such specifications (many people are accustomed to determine the class of headphones by their sensitivity parameter).

Closer Look


Actually, we might have predicted the arrival of multi-channel headphones. If people earn money on utterly useless inventions like flashlights on solar cells, then it’s possible to earn more on 5.1 headphones, the first model in the market! So, we have headphones with surround sound technology implemented. Let’s figure our how it works.

The Zalman ZM-RS6F is designed with an open acoustic enclosure. It is a known fact that some sounds are thrown to the outside in such headphones. Thus, the possible applications of such headphones are few. For example, it’s not advisable to use them in a noisy environment as external noises will seep into the earpieces; the contrary is true, too, as you can’t use them in places where silence is important (in sound recording studios and so on). Such headphones don’t suit for portable audio devices (audio players) either. So, there’s only one variant left – you can use them at home, with game consoles, DVD theaters and devices with a multi-channel audio output. Still, I think experienced users will prefer headphones of a higher class to enjoy high-quality audio. So, excluding this variant, too, we have arrived to the conclusion that the Zalman ZM-RS6F is for the market of game consoles with 3D sound. I think such a narrowly-limited application won’t tell well on the sales of this model. On the other hand, this device may become just fashionable or may make a good gift.

The Zalman ZM-RS6F has the freakish construction I’ve ever seen. Yes, the headphones look superb in their package, being an example of compactness. The caps are folded on the headband so the device takes the bare minimum of space. Similar versions are often offered by leading headphones manufacturers to DJs who are often monitoring sound with one ear. In this case, one cap is folded to the headband and its external part is equipped with a soft pad for comfort. Besides that, folded headphones often come with soft covers for storage and transportation. In our case, we have none of that: home users are the target auditory of the Zalman ZM-RS6F and they are not expected to take the headphones with them on the road. Thus, it turns out that the folded design of the headphones is useless in practice and only serves for fitting into the package.

A spring in the earpiece fastening would help – the earpiece is wobbly

The design of the earpieces and the headband is rather complex, but only offers two degrees of freedom because of the lack of ball swivels. The earpieces themselves are large leatherette pads wrapped over foam-rubber. They fully embrace your ears when you have the headphones on. Enclosures of this type are called circum-aural. You can easily remove them for service:

The enclosures are easily removable

Overall, the headphones are easy to take apart: you only have to undo four screws to take a look at the innards of an earpiece.

There are three low-Ohm speakers in the earpiece

The central speaker is 32 Ohms, and the side speakers are
16 Ohms each

Parts of an earpiece

The earpiece hides three speakers: one 32 Ohms and two 16 Ohms. The acoustic chamber is shaped as three rooms. There are compensators of the sound pressure between the rooms and resonance bass ports by means of which the headphones can reproduce deep basses. Overall, for reaching the maximum realism, the ZM-RS6F features six speakers (three in each earpiece), although we all know that ordinary stereophonic headphones can also achieve 3D sound by using special sound-positioning technologies.

It should also be noted that the headphones don’t reproduce the low-frequency subwoofer channel at all. When reproducing a test signal (from the audio card’s Control Panel), which allows checking out the operability of all the channels of the connected speaker system (in our case, of the Zalman headphones), the subwoofer channel dropped out of the overall picture. Our subsequent “dissection” confirmed that the wire of this channel is simply cut in each earpiece. Thus, the 5.1 headphones turned to be 5.0 ones actually! J

Three jacks are in the front

A potential purchaser can see that the Zalman ZM-RS6F model is six-channel headphones right away – the appropriate connectors are nestled like in a storefront, labeled Front, Rear and Center. At the same time, the manufacturer deviates from the standard color-coding of the connectors. Zalman has its own colors: white for the front pair of speakers (instead of the ordinary green), gray for the rear speakers (instead of black) and black for the center (instead of orange). Still, you won’t have to refer to the manual to plug everything correctly: you can see letters F, R and C stamped on the connectors.


I tested the Zalman ZM-RS6F headphones in two steps. First, I determined the audio characteristics of the device with the help of an audio analyzer. The second step implies a subjective evaluation of the sound quality in certain test compositions. A Creative Audigy 2 ZS audio card was the audio source in the tests.

When the test audio signal was synchronously outputted onto three speakers, the maximum sound pressure level was 118.7dB; when onto one speaker – it was 117.1dB. The highest values of the sound pressure fall onto the range of low frequencies. This value is always lower for middle and high frequencies. These values of sound pressure are too high and may easily harm your ears after a long exposure. When the test audio-track was being reproduced, the resonance ports were emitting a powerful stream of air as if there was a fan in the caps. For note: the pain threshold of the human ear is 120dB (after that the sound will harm your ears).

To pick up the frequency characteristic, we send an evenly-saturated signal, the so-called “pink noise”, to the headphones. The data were gathered with the help of a special calibrated microphone and a Euradio PRO600S spectrum-analyzer.

Frequency parameters of ZM-RS6F

This diagram allows evaluating the misbalance of the frequency characteristic and estimating the real range of frequencies as reproduced by the headphones. The screenshot above illustrates the point that our model does reproduce low and middle frequencies, but has some slumps in the area of high frequencies. The irregularity of the frequency chracteristic is very high there.

The Zalman ZM-RS6F was poor during aural tests: a muddy stereo-panorama, “cut-down” high frequencies, timbral misbalance, and a handful of other negative factors. Although these headphones are truly multi-channel, I would prefer standard stereophonic headphones to them. Moreover, you can purchase much better “ears” for their money.


I am personally very cautious about headphones from firms that are new to the field. Zalman just doesn’t have the rich experience of manufacturers like Sennheiser, Sony, Technics or Pioneer. At the same time, without doubt, the headphones from Zalman will enjoy a warm welcome in the gaming community as the main purpose of this model is in reproduction of sound when you can’t enable your speaker system. I’d like to warn you once again, though, that you should be wary of turning the volume to the maximum lest you become deaf.

When I was using the headphones, I often caught myself as if missing something. And yes, the ZM-RS6F would be better if it had a button to switch between Surround and Stereo modes. For example, this switch allows changing the Mono mode to Stereo and back in such specialized stereophonic headphones as the Pioneer SE-DJ5000. So why don’t they make a Surround/Stereo switch in a multi-channel model? I hope the engineering team from Zalman will consider my proposal in their future models, which are sure to appear. Among annoying trifles, I would mention the lack of a clip for the jointing cord, which many comfortable headphones models come with. Of course, this clip doesn’t affect the sound quality in any way, but it does affect the comfort of use.



Lastly, I would like to quote my friend, a DJ, “…any headphones, especially cheap ones, harm your ears”. Just remember that when you choose headphones for a long use.