New Logitech Speaker System Z623 Features THX

With the summer movie season in full swing, I find myself spending more and more time at our local theater. One of my very favorite parts of any movie outing is summed up by 3 little letters: THX.

THX certification is the mark of great audio system and at a THX certified theater you know you are going to experience the movie as the director intended.

Today, Logitech announced the Speaker System Z623 and now you can enjoy a THX certified audio experience at your home. This speaker system is great for movies, music, and gaming. Check out Senior Product Manager Garth Morgan’s video below to learn more about this amazing THX certified speaker system.


Product Line Manager, PC Speakers


  • Wow! The Sub looks like that one from the Z 5500 (which I love so much).
    Gonna be interesting…

  • With the exception of moving the controller to the satellite, it appears to essentially be the Z-2300 with updated ID. Anything new acoustically?

    • Hi Fred,

      Also new: the Z623 has added RCA connectivity for hooking up to a game console or TV.


  • hajj_3,

    This is simply a speaker system.
    Adding digital inputs would (afaik) require the addition of a DAC to the system and raise the price (unnecessarily) and increase the size of the unit.

    Given that the DACs in a computer are comparable to what you would get in most low-end systems (< several $k) it would be a redundant cost increase.

    If your source is giving you a digital output then instead you might want to consider a receiver coupled with an unpowered set of speakers.

    Correct me if I'm wrong.

  • Looks good. Already has the right stuff to make a hit, just like the Z-2300s, and the Z-2200s did, before that. Can’t wait to start carrying them in my store.

  • just another version of the Z2300, sigh. cant logitech come up sith something new and revolutinary….. maybe a cheaper system but with all the connections, like optical & Coaxial……

    On that part “Edifier” is much more worth the money……………. or maybe “altec Lansing” if they are available,,,,,,

  • Same drivers,same cabinets,same everything except the eye catching design,this should be the same if not worse than the Logitech z-2300.

    Seriously,i found these speakers locally available for pre-order at the price of 175 (200usd) euros!

    If they are similar to z-2300 sorry but they are not worth more than 70 euros.
    When i can get speakers like the Edifier s530 for 150 euros which sounds a million times better why get this?

    Sorry Logitech,make something better or at least something decent for its price and don’t advertise 200w RMS when they are 2x12w + 70w @ 10% THD with TDA based amplifier with 86db sensitivity because we’re not all ignorant out there about the marketing and the technical specs.

  • I completely agree with Truebass
    On the other hand, this is a downgraded z-2300, because it has a 7 inch sub, unlike the z-2300 which has an 8 inch sub. However, if these hit deeper than z-2300, I’ll gladly buy it. The z-2300 is extremely lacking in lower-end bass

  • I like many baby boomers have lost some of the high end of my hearing range from all those concerts and loud stereos years before.

    I was thinking about buying the z2300 but really I don’t want to have to turn it up too much. Right now I turn up speakers and I can hear them somewhat when I am standing outside and fear it would bother neighbors if I got a z623 or z2300.

    I have tile floors and the sound really is greater with all the hard surfaces to bounce off of right now. I end up turning the sound up just so I can hear the higher pitched nuances and that is too loud for the rest of the sound.

    Is anyone at Logitech thinking about making this unit wireless or that you could add wireless satellite so you can sit one on side tables near you so you where you could turn the treble up a bit more close to you while keeping the volume at a normal level.

    I have priced out hearing aids but a good set will cost 3K per ear and cheaper ones 1K per ear. These speakers are priced much better.

  • with built in optical audio delay for those fancy TV’s with picture correction chips , I have the Z5500THX and this is an issue with newer LCD TV’s

  • I have the 5500 sysyem with the massive sub and think it puts out too much bass even when turned down all the way. I hope they fixed that in this system.

  • Truebass, I think you have some misconception about Logitech Z-2300. I own one of them and let me tell you, the advertised 200W are not fake.

    The Z-2300 amplifier uses:
    Two 80W- TDA7295 amplifiers bridged together having a total of 2X80=160W for the subwoofer
    Two 60W-TDA7296 amplifiers one each for the satellites.

    So total RMS = 80(TDA7295) + 80(TDA7295) + 60(TDA7296) + 60(TDA7296) = 280W

    Logitech had reduced the total amplifier output from 280W to 200W since at peak power an amplifier will produce a lot of distortion & noise & thus fail to qualify the THX sound tests.

    So, reduced total RMS = 60(TDA7295) + 60(TDA7295) + 40(TDA7296) + 40(TDA7296) = 200W

    Your calculation of amplifier output using the RMS rating of the subwoofer & midrange speakers are not correct.

    The total RMS of the speakers is:
    [70 W (Subwoofer)] + [2 X 12 = 24(Midrange)] = 70 + 24 =94 W

    So, we see the speakers can handle 94W where as the amplifier is capable of 200W, i.e. more than two times. Well it is the norm, the amplifier is always rated twice the power the speakers can handle, since Logitech knows very well, that in general nobody can sustain 200W of power for a long period, so the user the user will usually hover below 100W for 98% of his total usage of the Z-2300. It same concept is also followed by Edifier.

    I also own an Edifier S730. It is one of the best 2.1 sets available. But let me tell you analog or not Logitech Z-2300 is way better than S730. The THX logo does not come for free on Z-2300.

    THX perform over 400 audio tests on the products to adorn THX logo. If you don’t believe go to the link given below and see it for yourself:

    Leave Edifier, Z-2300 beats Bose Companion 3, Series 2 in terms of sound quality. The biggest proof is the signal to noise ratio (SNR).

    Signal to Noise Ratio (SNR OR S/N): It is the ratio of signal power to the noise power corrupting the signal. This is usually rated in ‘db’ and anything over 100db is excellent, which means you get a cleaner sound.

    Z-2300: @ 1 kHz > 100dB
    S730: >=85dB

    I will comment on Z623 in my next post

  • Some facts about amplifiers & speakers of Logitech Z-2300 (contd.)

    » Power (RMS)
    The general rule of thumb is one should have an amplifier that can deliver power equal to twice the speaker’s continuous IEC power rating. This means that a speaker with a “nominal impedance” of 8 ohms and a continuous IEC power rating of 70 watts will require an amplifier that can produce 140 watts into an 8 ohm load. For a stereo pair of speakers, the amplifier should be rated at 140 watts per channel into 8 ohms.
    Now if you consider Z-2300 case you will find:
    1) Two 80W- TDA7295 (Total: 160W) amplifiers with power reduced to 120W are powering an 8 inch Tang Band 70W subwoofer which is almost half the amplifier rating.

    2) Each of the two 60W-TDA7296 amplifiers with power reduced to 40W are powering the 2.5 inch Tang Band 15W satellite speakers which is almost half the amplifier rating.

    The power of the amplifiers is reduced deliberately to avoid clipping.

    » Headroom
    A quality professional loudspeaker can handle transient peaks in excess of its rated power if the amplifier can deliver those peaks without distortion. Using an amp with some extra “headroom” will help assure that only clean, undistorted power gets to your speakers. Some professional amplifiers are designed so they have additional headroom. These amps can cleanly reproduce transient peaks that exceed the amplifier’s rated power.

    My comment on Z-623 s coming soon.

  • Subject: The Last of the Titans: Z-2300 and comparison with its humble successor the Z-623

    Me, Different: Generally the users provide a very subjective view of the product that they have bought but what I will try to provide in this review of the Z2300 is more from a technical standpoint and as well as my subjective point of view.
    Well, I am sorry to say that though Z-623 is the successor of Z-2300, it did not had enough in it to beat the Z-2300, be it acoustic performance or just looks. One of my friends bought the Z-623 today, so I was lucky to see it in flesh and hear the sound quality of the set and also compare it with my Z-2300 which I have been using for the past two years. My friend also had the same opinion about the Z-623.

    On the positive side I found Z-623 to be much lighter & smaller than Z-2300. Definitely it’s a space saver, but if you purely consider the acoustic performance of sound systems generally the bigger & heavier becomes the winner. Why? Let me describe …

    1) Stats: Both Z-623 & Z-2300 are claimed by Logitech to have same performance. Both had a total RMS power of 200 W & are THX certified. Power distribution is as follows :

    Z-2300 -> 120 W (Subwoofer) + 2 X 40 W (Satellites)
    Z-623 -> 130 W (Subwoofer) + 2 X 35 W (Satellites)

    2) Subwoofer:
    Z-2300 -> The subwoofer is huge, in every sense of the word. The behemoth measures 11” (H) X 11” (W) X 15” (D), and its output could rattle the paint off your walls. The wall of the sub is made of 16 mm thick medium density fiberboard (MDF). The wall thickness is quite impressive which along with internal braces in the joints adds tremendous strength to the box in order to withstand the heavy duty sound waves produced by the massive 8 inch long throw 70W Tang Band (W8-670Q) front facing driver. The subwoofer also houses a patented “U” shaped exponentially increasing bass reflex port to produce a deep and rich bass experience. The enclosure is very deep, which is obviously good from an acoustical standpoint. Aesthetically, Z-2300 subwoofer is much better looking with its silver & black tones than the hideous full black Z-623’s subwoofer. I especially liked the grill cover of Z-2300 driver than the protruding one of Z-623.

    Z623 -> The Z623’s subwoofer is two thirds the size of Z-2300. It measures 11.9” (H) X 11.1” (W) X 10.4” (D). So, the height & width are almost identical but the depth of the box had been reduced by almost 5 inches. From an acoustical standpoint this is not positive, since at least for subwoofers the simple theory of “The Bigger the Better” hold absolutely true.

    Also, the driver is smaller measuring 7 inches which is also a negative from an acoustical standpoint. What I found amusing that how a 7” driver can handle 130 W when the 8” driver of Z-2300 was always on overdrive mode handling 120 W. This is the biggest proof that the amount of bass produced in the subwoofer had reduced considerably.

    The Z-623’s subwoofer is not only smaller but also half the weight of Z-2300’s sub. This is due to a smaller driver with a smaller magnet enclosed in a smaller box with a thinner wall thickness than Z-2300. So, Z-2300 have a better subwoofer assembly than Z-623. The quality of construction, fit & finish are of very high order in both cases.

    3)Satellites: Both Z-2300 & Z-623 uses 2.5 inch polished aluminum phase plug drivers in their satellites. Z-623’s satellites are complete black units and are plain ugly, where as Z-2300’s satellites with silver & black tones are beautifully crafted and looks like a piece of art. The drivers of Z-2300 are 12W units made by Tang Band (W3-594SB).

    Coming to the performance aspect, both are almost identical, Z-2300 having a slight advantage in producing a little bit better high frequency response. With the polished aluminum phase plug drivers helping to reduce the path length differences about the cone surface, you get a smoothing and reinforcing the frequency response, particularly in terms of the highest frequencies the driver is capable of.

    Other potential benefits gained from incorporating polished aluminum phase plug drivers include eliminating compression under the dust cap and reducing distortion in extreme cases. There is some thermal dissipation one gives up by doing this, but the phase plug itself can serve as a heat sink for the voice coil and magnet pole.

    4)Amplifier: Both Z-2300 & Z-623 houses the amplifier in their subwoofer assembly.

    Z-2300-> The amplifier in Z-2300 is of very high quality. It is powered by a toroidal transformer made by Ten Pao International. Judging by the size of the core and the thickness of the wire in the secondary windings, the power is very decent. A toroidal transformer uses a doughnut shaped core & is much slimmer than a conventional (EI) transformer and at the same time it is much more expensive than a conventional transformer. A toroidal transformer has so many performance advantages over conventional transformer that it is hard to describe here other than to provide the performance ratio.
    Toroidal : Conventional :: 158 : 5

    The amplifier uses:

    i) Two STMicroelectronics 80W- TDA7295 amplifiers bridged together to provide a total of 2 X 80=160W for the subwoofer.
    ii) Two STMicroelectronics 60W-TDA7296 amplifiers powering each of the satellites.
    iii) A Japan Radio Corporation’s JRC-4565 operational amplifier for pre-amplification.
    iv) Filtering of the audio signal is done by two beefy 10,000 uF capacitors.

    Total RMS Power = 80(TDA7295) + 80(TDA7295) + 60(TDA7296) + 60(TDA7296) = 280W

    Now any amplifier will produce a lot of distortion & noise at the peak. So, in order to produce distortion free, ultra linear sound the amplifiers generally needs to reduce its output peak power by 25% or more.

    Reduced Total RMS Power = 60(TDA7295) + 60(TDA7295) + 40(TDA7296) + 40(TDA7296) = 200W

    The general rule of thumb is one should have an amplifier that can deliver power equal to twice the speaker’s continuous IEC power rating. This means that a speaker with a “nominal impedance” of 8 ohms and a continuous IEC power rating of 70 watts will require an amplifier that can produce 140 watts into an 8 ohm load. For a stereo pair of speakers, the amplifier should be rated at 140 watts per channel into 8 ohms.

    This is because a quality speaker can handle transient peaks in excess of its rated power if the amplifier can deliver those peaks without distortion. Using an amplifier with some extra “headroom” will help assure that only clean, undistorted power gets to your speakers.

    The total continuous IEC power rating the speakers is:
    [70 W (Subwoofer)] + [2 X 12 = 24(Satellites)] = 70 + 24 =94 W

    So, in this case the 200 W amplifier of Z-2300 is almost twice as powerful as the speaker’s 94 W continuous IEC power rating.

    There is a massive heatsink located at the back of the subwoofer to cool the amplifier that pumps 200 watts of power. Toroidal transformers stay magnetized once turned off. This again testifies to their efficiency, but if the transformer is turned back on during the same positive AC cycle, higher currents are drawn from the line. This condition is called in-rush and it only occurs if the conditions are just right and only for a maximum Ω cycle (about 0.008 seconds). It is not dangerous to the transformer and is easily rectified with the help of a slow blow fuse found at the back of the subwoofer of Z-2300. An additional power switch is also provided.

    Overall I am highly satisfied with the design, detailing and high quality components used along with the built in safety features of the amplifier.

    Z623-> I am unable to give you a clear detail of the Z-623 amplifier, since my friend was reluctant to open the newly purchased set, which is quite understandable. But minutely looking at the subwoofer, I found out that there is no slow blow fuse. This means, that either the set is using a more conventional EI type transformer to power the amplifier in order to save cost and thus sacrificing huge performance benefit that a toroidal transformer can provide or the safety mechanism have been deliberately removed.

    Also, there are no heatsink at the back of the subwoofer which means that heat is not dissipated properly from the amplifier. After a prolonged use (say 4 hrs) this can lead to overheating and damage the amplifier. Again, this may be done to cut cost.

    5) Controls:
    Z-2300-> The control pod of the Z-2300 is quite simple and minimalistic, which I prefer. No fancy lights just a big volume knob, a bass control, a 3.5 mm headphone jack, power LED and a power button. You can keep the control pod on your desk where ever you like and the controls are very convenient.

    Z623-> The volume knob, bass control, 3.5 mm headphone jack, power LED and power button are all integrated on the right satellite. Now every time you need to make an adjustment you have to reach your hand out to the right satellite. This becomes very irritating and once again reminds me that it is a deliberate move by Logitech to cut cost.

    6) Market Positioning :
    Z-2300-> When Logitech introduced Z-2300 back in 2004, it was a THX certified premium quality top of the range product. The Logitech engineers in the lab where given a clear goal i.e. to create the ultimate 2.1 multimedia speaker system in the world. They were not concerned about the price, they were more concerned about the performance & quality which lead in using premium quality components, be it electronic components, speakers used, wooden casings of the subwoofers, plastic casings of the satellites and even the wires used to connect the components. Price was never an issue, performance was. This single mindedness of the engineers produced a unique product, and Z-2300 was born.

    Z-623-> Logitech introduced Z-623 in 2010 six years after Z-2300 reign. Actually I cannot recall of a 2.1 PC speaker that remained at the top of the performance charts for straight six years. They had to make the successor not because Z-2300 was getting old and becoming incompetent, believe me it is still is the king, but because the rival manufactures like Altec Lansing, Edifier, Creative, Sony etc are producing cheaper sets of same wattage and same configuration and labeling them as their premium product. Also 2.1 speakers sets are no more the cash cows of audio manufactures, rather these companies makes a lot of profit from selling the 5.1 & 7.1 speakers sets.

    Thus, engineers this time were given a strict goal to make a good set at a certain price limit during Z-623 designing phase. So what you get is a good product but not an excellent one like Z-2300. This is evident when Logitech’s Senior Product Manager Garth Morgan’s introduced the Z-623 and called it a “cleverly engineered product” which indirectly means “Tried our best to keep minimum performance loss in comparison to Z-2300 and at the same time cut cost in every possible way”.

    7)THX: THX stands for Tomlinson Holman’s eXperiment. A THX Certified Multimedia Speaker system is designed for those who crave the power and performance of home theater and studio sound at the desktop.THX certification recreates peak, Reference Level quality at your desktop listening position.

    What is Reference Level? THX Reference Level, a setting designed to mirror the exact volume level used by movie makers and sound artists in the studio. When you are watching a movie on a THX Certified Multimedia Speaker System, you experience every sound element exactly like it was produced by the filmmaker—with the same fidelity, detail and clarity.
    Speakers that can achieve THX Reference Level is no simple task. It requires a tremendous amount of power to drive an audio system effortlessly without clipping or distorting. THX Certified Multimedia Speaker Systems are designed to recreate Reference Level with minimal distortion.

    THX worked closely with Logitech during product development, ensuring the two-satellite and subwoofer Z-2300 & Z-623 speaker system was meticulously mapped to THX design standards. Then, THX performed more than 400 bench tests, including frequency response, noise, distortion and power. The result is a THX Certified Multimedia Speaker system that delivers THX Reference Level sound pressure and fidelity – letting you hear every bass note, sound effect and dialogue as it was created in the studio.

    Performance Benefits:
    400 Bench Tests: THX acoustic and electrical bench tests ensure accurate and powerful audio performance.
    THX Reference Level: Designed to mirror the performance characteristics of professional studio speakers, recreating peak, THX Reference Level quality.
    Wide Bandwidth: Low frequency extension of satellite speakers ensures a smooth and balanced audio experience when sound pans from satellites to subwoofer.
    Desktop Engineered: The Logitech Z-2300 or Z-623 are perfect for PC gaming, podcast production, audio and video editing, and enjoying music and movie applications on your desktop.
    8) Performance:
    Music: Throughout my 2 years with Z2300, one thing became very clear; these are very neutral sounding speakers. They are not too peaky or bright, and they are definitely not too boomy or sloppy. What is produced by these speakers is very smooth, and very pleasant to listen to. The one thing that does come to mind when listening though is power. Z-2300 is capable of producing 117 dB which is a world record for a 2.1 multimedia speaker system. The subwoofer lets itself be known with its tight & precise bass which at times are powerful enough to knock the wind out of your lungs. The satellites feature a nice, natural sound with excellent representation. If the user wants, they can boost the subwoofer levels through the roof though my ears will be bleeding by then.

    I am dealing with one of the best solutions for pure listening pleasure, with a clean sound devoid of any colorings, embellishment or ornamentation in the sound, commonly found in Altec Lansing and Creative speaker systems. Now I can easily hear many of the previously obscure details in the compositions of a complicated music composition, and can clearly set apart all the instruments used in the music composition, thus I am able to focus not only on the primary instrument, which is audible, but also on the fact that what instrument I want to hear.

    Even though these are not two way satellites, the phase plug allows the 2.5” driver to more accurately reproduce the high end of the frequency spectrum. This is achieved by removing the “dead” mass at the center of the driver, all the while helping to focus the sound coming off of the driver towards the user (and not towards the other side of the speaker). This plug essentially allows the mid-range driver to reproduce tweeter effects to a great degree.

    There is no background noise with these speakers, and definitely none of the hiss that my Altec Lansing MX-5021 suffered from. The analog input was very clean, and it was able to reproduce the sound with great accuracy.

    Movies: These speakers are exceptionally clear at reproducing dialogue, as well as action, in a wide variety of movies. Even when there is a lot of action and music on screen, dialogue is never drowned out, nor does it get muddy or indistinct. The lack of any kind of hiss also helps in playback, as the softer, more subtle scenes draw the viewer into the movie. The satellites do an outstanding job of reproduction.

    When the action gets heavy, the subwoofer really kicks in. The bass is tight and strong, and it will make a user’s chest thump if the content calls for it. Low end effects can really help to heighten the tension of a scene, as well as help to expand the overall environment. The subwoofer on these speakers is able to handle nearly every explosive scene thrown at it. Never once did it sound like the subwoofer bottomed out, or sound strained, or even chuffed. The ported design is surprisingly quiet, considering in other designs I have heard quite clearly the air moving in and out. Overall, for a 2.1 set of speakers, these turned out to be quite good for movie reproduction.

    Games: This is probably the area where these speakers excel the most. The satellites are very clear in gaming, and their mid-bass is very present, but not overpowering. High frequency sounds are usually not present in most games, so the lack of a tweeter here does not affect gaming performance one bit. The satellites are able to provide excellent sound in a variety of gaming situations, and the ability to accurately reproduce the HRTF effects makes for a very immersive experience.

    The subwoofer really gets a workout from many of the new action games, and it keeps asking for more. In titles such as Need for Speed Undercover, the subwoofer plays a very large part in the action.

    Z-623-> The sound characteristics of Z-623 near identical to Z-2300 be it music, movies or games, the only difference being the magnitude of the sound. For sure Z-623 is not as loud as Z-2300’s 117 dB maybe it hovers around 107 dB. Z-2300 seems have a little bit more precise and deeper bass response from its 8 inch driver where as Z-623 have a 7 inch one, though the midrange is equal for both the sets but Z-2300 had little edge on treble response than Z-623. But if you have not experienced the Z-2300, its successor the Z-623 will blow you away. All in all Z-623 is a solid set, capable to blow away the Altec Lansing Expressionist Ultra, Creative Gigaworks T3 or Sony SRS DB500. As for Z-2300 it is still the king of this heard.

    Verdict: Z-2300 is hitting the end of its production cycle. It is the last of the titans which is finally going to take slumber. But it is going to rule the hearts of those who were lucky enough to possessed them and experience their performance. If you really need a high end 2.1 THX certified multimedia speaker system don’t waste any more time and get a Z-2300 while it is still available, and if they are not then only but a Z-623.

  • RishiGuru, I believe he was just trying to be funny arguing your 7page comment with his one sentence response.

    Anyways, good shit man, this was very helpful. Also, I read the full post and I already feel 10x smarter.

  • Although I would love to agree what Rishiguru says but 80% of the comments he made are not his personal views abt the product/s or say not the opinions that came out of his own mind and heart; If you can search google well, you will find that those same articles, viewpoints and comments abt that particular speaker/s have been by other experts or product reviewers who put or placed or published them in other forums or sites. Rishiguy just copied them and pasted them here. Cmon Rishi…..come up with something original.

  • Odiofile your comments make me laugh. First of all i at least tried to expresses some opinion about the product. All you could do is to comment on what others are commenting. So first of all you are “off topic”.

    Secondly, what i said was completely my personal opinion. If some website also verifies the same with me it only proves that i made a perfect opinion about the product. So, thank you for that !!!

  • Hi, Does the satellites work separately, or are they powered only through the sub? Id like to have a 2.1 system with satellites I can grab with me on the road, for my presentations.

  • Dear Users,

    could any one please let me know that Z623 can beused with both supply voltage (110V -50hz US and 220V -60Hz Europe) ???


    • Hi Amit,
      If you purchase the product on in your country it should work with the electrical wiring in your country.


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