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Logi Rook
RishiGuru
Posts: 95
Registered: ‎09-29-2010

Is Logitech Z-623 the true successor of Logitech Z-2300?

[ Edited ]

PART-I

 

Logitech Z-623



Logitech Z-2300


Even though Z-623 is touted by Logitech as the successor of Z-2300, I personally believe it does not packs the punch or have enough performance in it to be in the same league of Z-2300, let alone beat it. My beliefs were confirmed when my friend bought a Z-623, who also happens to owns a Z-2300. We did a full day audition of the Z-623 & compared it with the Z-2300 in every possible way, be it acoustic performance, quality of hardware used or just looks.

Note: I would recommend to read my post “Logitech Z-2300 : The Last of the Titans” prior to continuing with this comparison. A complete knowledge on Z-2300 will definitely help you to get a clearer picture about this comparison. The link to the my review of Z-2300 in this forum is provided below:

Logitech Z-2300 Review

MARKET POSITIONING

Z-2300: When Logitech introduced Z-2300 way 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 of the system 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.

If you consider that way back in the year 2000 when Logitech was known as a cheap speaker manufacturer and could not even meet the standards of Altec Lancing let alone Klipsch computer audio products, they made a huge effort back then in order to make a big step forward and used better quality components for their THX certified audio system lineup than they have ever done before thus increasing cost. My "Price was never an issue, performance was" statement is in context of my above view. Today when we compare the Z-2300 from an el chepo manufacturer Logitech with the HiFi maker company like Klipsch producing Promedia 2.1 as a computer multimedia speaker system, you find both of them being in the same segment going head to head in terms of audio performance and in many occasions Z-2300 coming out as a clear winner. Atleast we have to give credit to Logitech that that could produce a multimedia speaker system that can meet the standards of a Klipsch product. I give full marks to Logitech only for this effort.


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 which claim to have the same power & performance of Z-2300 while using cheaper materials and then labeling them as their premium products. 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, I believe this time the engineers were given a strict goal during the designing phase, i.e. to make a speaker set that beats its opposition like Altec Lansing MX-6021, Sony SRS DB-500, Edifier S530 or Creative Gigaworks T3 by a small margin. Z-623 was not designed to reach the same level of acoustical performance of Z-2300, let alone beat it. After all there is no need to provide Z-2300 levels of performance when Z-2300 itself will be discontinued.

Also from the marketing point of view Z-623 having the same performance level of Z-2300 was useless since any marketing division want a system that is better than their oppositions, so they can advertise that and get the propaganda.
Consider the case of these two 200W RMS 2.1 speaker sets.

Let us assume that Altec Lancing uses hardware worth $80 and have assembling cost of $10 per set of MX-6021 and sells it at $150. Profit = 150 – (80+10) = $60

Suppose in order to beat AL MX-6021, Logitech uses hardware worth $90 and have assembling cost of $10 per set of Z-623 and sells it at $150. Profit = 150 – (90+10) = $50

So, Logitech gives hardware worth $10 more thus having more performance than MX-6021 at the same price in order to garner more sells at that price range.

Now, if Z-623 was supposed to beat Z-2300, then Logitech would have to use hardware worth $120 and have assembling cost of $10 per set of Z-623 and sells it at $150. Profit = 150 – (120+10) = $20

So, Logitech’s profit margin would have fallen from $50 to just $20 per set. And since Z-2300 will be discontinued & the current speaker sets having way below performance level than that of Z-2300, $50 profit per set was found more of a sensible option and correct from the logical point of view. If I was at the helm of Logitech I would have done that too. Unfortunately for customers, what they get is a good product but not an excellent one like Z-2300.

SPECIFICATIONS

Z-2300
Audio Quality Certification: THX certified
Total RMS Power: 200W [FTC rated power] 
Total Continuous Power: 120W [Estimated] 
System THD: Better than 0.05% before clipping 
Total Peak Power: 400W 
Power distribution: 120 W (Subwoofer) + 2 X 40 W (Satellites)
Subwoofer: 120 W @ 8 ohms
Subwoofer Size (inch): 8
Satellites: 80 W (2 X 40 W) @ 8 ohms
Satellite Size (inch): 2.5
Frequency response: 35 Hz - 20 kHz
Signal to noise ratio(SNR): @ 1kHz > 100dB
Sound Pressure Level (SPL): 117db
Subwoofer dimensions(HWD): 11" X 11" X 15"
Satellite dimensions(HWD): 6.75" X 3.5" X 6"
Total weight : 15 Kg

Z-623
Audio Quality Certification: THX certified
Total Power: 200W <-- Is it FTC rated power? No Mention. Why?
System THD: No Mention. Why?
Total Peak Power: ???? 
Power distribution: 130 W (Subwoofer) + 2 X 35 W (Satellites)
Subwoofer: 130 W @ 8 ohms
Subwoofer Size (inch): 7
Satellites: 70 W (2 X 35 W) @ 6 ohms
Satellite Size (inch): 2.5
Frequency response: No Mention. Why?
Signal to noise ratio(SNR): No Mention. Why?
Sound Pressure Level (SPL): No Mention. Why?
Subwoofer dimensions(HWD): 12" X 11" X 10"
Satellite dimensions(HWD): Unknown
Total weight : 10 Kg [5 kg lighter than Z-2300]

DELIBERATE MEASURES TO HIDE PERFORMANCE DEFICIENCIES OF Z-623 IN RESPECT TO Z-2300

Frequency Response: Frequency response is the measure of any system's output spectrum response to an input signal. Humans are able to hear any sound between 20Hz to 20kHz. Any multimedia speaker system that can cover this entire range is regarded as a great achievement for the manufacturer so that the user can hear each &every note of the music playing.

While it is quite easy to go up to 20kHz to produce high frequency (treble), a manufacturer have to spend a lot of money in the hardware department in order to go way down in the frequency spectrum and reach 20 Hz (Bass). To produce frequencies at 20 Hz you need a bass driver which is at least 12 inch or more in diameter and also have lots of power from the amplifier to power that driver in order to move huge volumes of air.

Since Z-2300 uses a 8 inch bass driver it can go as low as 35Hz and its frequency response is in between 35Hz–20kHz which is quite a respectable figure. For Z-623 there is no mention of frequency response of the set in their website. Why? Is it because Z-623 7 inch bass driver being an inch shorter than Z-2300 was not able to go as low as 35Hz as in Z-2300 could have and hover around 45-50Hz? I think so.

System THD: The total harmonic distortion (THD) is there to give us a measure of how much the audio signal is distorted when playing the system. Z-2300 had better than 0.05% THD before clipping which was excellent from acoustical performance point of view. In Z-623 there is no mention of these criteria in their website. Why? Is it because Z-623 THD is nowhere near that of Z-2300? I think so.

SNR: Signal-to-noise ratio (SNR) is a measure used in science and engineering to quantify how much a signal has been corrupted by noise. It is defined as the ratio of signal power to the noise power corrupting the signal. Z-2300 had hifi level 100dB SNR which was way better than 70-80 dB SNR its opposition was able to manage. For example, Altec Lansing MX-6021 have only 75db SNR. For Z-623 there is no mention of these criteria in their website. Why? Is it because Z-623 SNR also hovers at around 75dB and thus nowhere near that of Z-2300? I think so.

FTC rated power: FTC as a governing body provides strict rules for output power claim. According to their rule, wattages stated are the sine wave continuous average power output measured using US FTC Title 16 Part 432 (RMS) rating, not “peak” or maximum power output. For Z-2300 Logitech clearly stated 200W of FTC Rated Power & 400W RMS of peak power. For Z-623 Logitech just states 200 W RMS of power. Why? Is it because Z-623 was not able to match the power output of Z-2300? I think so.

Weight: For multimedia speaker systems, weight is an indicator of good, robust design because it suggests that the speakers are made of thick MDF, have big drivers (speakers) with large magnets in them to handle lots of power from the amplifier, and therefore have plenty of capacity. Also weight is an good indicator for the internal amplifier because it suggests that the amplifier’s important internal components--the power transformer, heat sinks, and storage capacitors -- are large, and therefore have plenty of capacity to process and store large amounts of power to handle loud dynamic peaks without distortion.

Z-623 is 5 kilograms lighter than Z-2300. I mean you can buy a moderately good 2.1 speaker system which weighs 5 kg. It also much smaller than Z-2300 and a space saver too, but if you look purely from an acoustical performance point of view of any sound systems generally the bigger & heavier becomes the winner. Why? Let me describe …

SUBWOOFER COMPARISON

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 both rattle the paint off your walls & take the wind out of your lungs at the same time. The enclosure is very deep, which is great from an acoustical performance viewpoint. The subwoofer weighs 12 kilograms and is a back breaker for sure.

Actually, this subwoofer was designed for Z-560 way back in the year 2000. Z-560 was the first THX certified multimedia speaker system from Logitech and was a big gamble at that time. Nobody was quite sure how the market will react in accepting a high end computer speaker from this unknown brand. But it seems that the gamble finally paid off and ever since this Holy Grail subwoofer have been used in their THX certified speaker systems line up for the past decade as below:
Z-560 [first THX certified 4.1 system, launched in the year 2000]
Z-680 [first THX certified 5.1 system, launched in the year 2002]
Z-2200 [first THX certified 2.1 system, launched in the year 2003]
Z-2300 [second THX certified 2.1 system, with minor updations on Z-2200 launched in the year 2004]

There is a department in Logitech that exclusively deals with audio products and are better known as Logitech Sound Central. The link to the website is provided here:Logitech Sound Central

They state: “We don’t simply buy parts off the shelf. We laser tune different types of drivers. We modify the shapes, experiment with materials, and use digital components to improve sound quality. Our goal is to deliver fidelity as close to the original sound as possible.

Logitech Sound Central testing the bass driver of Z-5500


The subwoofer also houses a patented “U” shaped exponentially increasing bass reflex port to produce distortion free deep and rich bass experience. The enclosure is very deep, which is obviously good from an acoustical standpoint.

Z623: The Z623’s subwoofer is two thirds the size of Z-2300. It measures 12” (H) X 11” (W) X 10.5” (D). Logitech kept the height & width almost identical but the depth of the box was drastically reduced by near 5 inches. From performance aspect this can never be considered a positive, since at least for subwoofers the simple theory of “The Bigger the Better” hold absolutely true.

From a technical point of view, Z-623 does not need a subwoofer enclosure as big as Z-2300 since the bass driver is an inch smaller in diameter measuring 7 inches and thus requiring a lot less volume of air inside the enclosure. But in return, Z-623 subwoofer will be much less powerful as compared to Z-2300. I think the 7 inch bass driver have a rated input power of 50W RMS if you consider the 8 inch bass driver of Z-2300 was rated 80W RMS.

What I found amusing is that Logitech states this 7 inch bass driver can is capable to handle 130W RMS of power from the amplifier when the 8 inch bass driver of Z-2300 was always on overdrive mode handling its 120W RMS. This is the biggest proof that there is something fishy about the stated power of Z-623 & the amount of bass produced by the subwoofer or its loudness have substantially reduced by a good margin.

Also, the Z-623 subwoofer is nearly 4 kilograms lighter than Z-2300 sub. Where does this 4 Kilos go? Just vanished? Or is this is due to a smaller bass driver with a smaller magnet being enclosed in a smaller subwoofer enclosure with a thinner wall thickness than that of Z-2300?

SATELLITE COMPARISON

Z-2300 uses 2.5 inch polished aluminum phase plug drivers in their satellites and are beautifully crafted to look like a piece of art. The 12W satellite drivers that Z-2300 uses are again from an unknown speaker company and does not in any way relate to 3 inch Tang Band (W3-594SB) units. I estimate a rated power of 10W & a max of 20W. But since these drivers get audio frequencies ranging from 150Hz to 20kHz, the power handling capability increases by at least two times. So these speakers can handle anything between 20W to 40W. 

Z-623 uses the same 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.

AMPLIFIER COMPARISON

Both Z-2300 & Z-623 houses the amplifier in their subwoofer assembly.

Z-2300:

Power Supply

The power supply of an audio amplifier is of vital importance, since it provides all the juice required by power amplifiers to drive the big speakers. An underperforming power supply will seriously limit the performance of an amplifier. 

The power supply consist of:

i) A center tapped toroidal transformer manufactured by Ten Pao International. This transformer is rated at 150.9VA with +/- 20.1VAC secondary, 3.75A. 

ii) A metal cased bridged rectifier to provide full-wave rectification from +/- 20.1 VAC to DC.

iii) A pair of CapXon 10,000 uF, 35V capacitors one for + 20.1 VDC and the another for – 20.1 VDC acting as ripple filters in order to smooth the DC output.

A toroidal transformer uses a doughnut shaped core & is much slimmer than a conventional (EI) transformer. It has numerous advantages over EI type such as low weight, low hum, low noise and also being smaller in size than an equivalent EI type. On the downside they are much more expensive than a conventional EI transformer. But it is worth the pay since you get better performance. A toroidal transformer has so many other performance advantages over EI type that it is hard to describe here other than to provide the performance ratio. Toroidal : Conventional(EI) :: 158 : 5 . It you want to know more in details go to the link below: 
Bryston Transformers

The transformer used here is rated to have an output of two times 20.1VAC when it has its rated load. So its resistance has already dropped the open circuit voltage and its peak will be 1.414 times higher which happens to be 28.4VAC. A single rectifier here drops it by 1VDC to 27.4VDC and smoothing the ripple by the power capacitors drops it by another 1VDC to 26.4VDC.

So, DC voltage supplied by the power supply is +/- 26.4 VDC, the current being 3.75 A. 

Logi Rook
RishiGuru
Posts: 95
Registered: ‎09-29-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

[ Edited ]

PART-II

 

Amplifier Chips


Z-2300 uses Class-AB power amplifiers from STMicrolectronics. STMicrolectronic is a very renowned name in audio amplifier market.

The amplifiers used are:

i) A Japan Radio Corporation’s JRC-4565 operational amplifier. JRC-4565 is a dual op-amp which means it has two op-amps inside it to handle stereo channels.

ii) Two voltage regulators a 78M18 and a 79M18 supplying +/- 18 VDC respectively to feed JRC-4565 op-amp from the +/- 26.4 VDC power rail.

iii) Four STMicroelectronics, Class-AB, 60W, TDA7296 power amplifiers. Two of these are used to power each satellites while the other two are bridged together powering the subwoofer.

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.

Also surfing the net I found out Logitech have completely replaced the Z-2300’s 200W [FTC Power Rated] Class-AB amplifier module powered with expensive toroidal transformer with cheapish Class-D amplifiers powered by switch mode power supplies (SMPS) as found inside our computers. The trend to Class-D was first started by Logitech in Z-Cinema which was a hybrid Class-AB/ Class-D. 

TRUE CONTINIOUS POWER OUTPUT FIGURES 

Z-2300 amplifier’s continuous power output capability 

Remember that Z-2300 produces 200W of FTC Rated Power. But this is by no means continuous power. In order to produce 200W of continuous power, an amplifier will need a transformer that is capable of to deliver a minimum of 1.27 times the claimed wattage. Since Watt is volts multiplied by ampere, 200W of output requires 254 watts or 254VA transformer as a minimum requirement.

So, Z-2300’s supplied 150.9VA will produce a maximum of: (200/254) X 150.9 = 119W =~ 120W of continuous power @ 0.5% THD @ 8 ohms @ 26.4 VDC

Since the ratio of power distribution between the subwoofer and the satellites is in the order of 3:2, the subwoofer is capable to produce 72W of continuous power while each satellite gets 24W of continuous power.

This becomes even more evident from the fact that the bass driver has a rated input power 80W, while the satellite speakers can handle anything between 20 to 40 watts. 

Z-623 amplifier’s continuous power output capability 

Considering the case of Logitech Z-Cinema claimed 180W, I dismantled it myself and found out
1) One Philips TDA8920 100 watts Class D amplifier for the subwoofer. 
2) One Philips TDA8922 50 watts Class D amplifier supplying 25W to each of the midrange speakers of the two satellites.
3) One STMicroelectronics TDA7269 20 watts Class AB amplifier supplying 10W to each of the tweeters of the two satellites.

Total maximum amplifier chip power of Z-Cinema is 100 + 50 + 20 = 170W, where as
Total maximum amplifier chip power of Z-2300 is 4 X 60 = 240W

Logitech Z-Cinema


Now look at the Z-Cinema's switching power supply powering the amplifier as below:



Take at even closer look at the main component of the Z-Cinema's switching power supply :



It is clearly stated, MAX TOTAL OUTPUT POWER 83.3W

So, Z-Cinema’s supplied 83.3W will produce a maximum of: (83.3/1.11) = 75W of continuous power.

Since the 75W continuous power of Z-Cinema is said to produce 180W by Logitech, I believe the Z-623 maybe have at around 80W continuous power and is down by 40W to the 120W continuous power of Z-2300. Also the switching power supplies of Z-623 can never go beyond their rated power[93.3W estimated]. Where as the Z-2300 with its toroidal transformer & filter capacitors can easily produce 200W for a short period of time. 

Discrepancies about Power Output Figures 

Remember that most audio amplifiers do not have power supplies capable of driving their rated power continuously. This holds absolutely true for all computer multimedia speakers systems & consumer home audio products. Only HiFi systems costing a lot of money have power supplies that can match the continuous power rating of the amplifiers.

This is because music is not like a continuous sine wave. It has peaks of intensity, then relatively quiet periods. If music has a 20dB dynamic range then if the peaks are 200W, the average power is probably around 5W. 

A transformer can sometimes go well beyond its rated power output for small amount of time to handle these peaks of intensity. For example the 150.9VA transformer of Z-2300 can go up to 180VA to handle the peaks & produce 140W power for that moment. 

If even further power is required to handle this peaks of intensity, say 200W, then the additional 60W is supplied by the two large 10,000uF, 35V power supply filter capacitors of Z-2300 for this short period of time. The filter capacitors can charge back up during the relatively quiet periods.

So the 150.9 VA transformer of Z-2300 is perfectly capable to deliver 120W of continuous power & can easily handle peaks reaching 200W. Remember that the Z-623’s switching power supply is not able to attain this feat and stays at 93.3W. I think that is the reason why Logitech have not quoted peak power output of Z-623

Also Logitech states that Z-2300 have a Total RMS Power of 200W. Look at the absence of the “continuous” word. Except HiFi systems, you will always find these consumer audio companies talking about “Total RMS Power”, “FTC Rated Power”,“Power”, “Total Peak Power”, “System Power”, “Music Power”, “Peak Music Power Output (PMPO)”,…………….. and the list goes on. But you will never find them talking about “Continuous Power” which happens to be the actual power of the amplifier.

Reasons for using Class-AB Power Amplifiers

A quick look at many new low power speaker amplifiers on the market highlights the move to Class-D audio performance, but when it comes to low distortion and low noise and best sound quality, Class-AB still has the edge.

Class-AB architecture offers a signal to noise plus distortion ratio of up to 10 times better than its equivalent Class-D neighbour as well as providing a much simpler architecture which can be tweaked as required, without the need for reactive filter components on the output and the electromagnetic radiation resulting from an output stage switching at a few hundred kHz. Class-D amplification has inherent distortion in it and therefore is predominantly used in lower bandwidth amplification like in subwoofers. In other words it is quite impossible for a Class-D to achieve the level of linearity in frequency response produced by a Class-AB amplifier. 

Ultimately it comes down to what you want, for efficiency and cost effectiveness Class-D are best, but if you are ready to sacrifice some efficiency & increase cost for the sake of sound quality then Class-AB are the best. In other words Class-A amps sound the best, cost the most, and are the least practical. They waste power and return very clean signals. Class-AB amps dominate the market and rival the best Class-A amps in sound quality. They use less power than Class-A, and can be cheaper, smaller, cooler, and lighter. Class-D amps are even smaller than Class-AB amps and more efficient, because they use high-speed switching rather than linear control.

The most important reason behind which multimedia speaker manufactures are switching from Class-AB to Class-D is to increase profit margin. Class-D is very cheap to produce and does not need require a big extruded aluminum heat sink or expensive toroidal transformers. They are basically switching power supplies but utilize pulse width modulation so as to be able to reproduce and amplify an alternating current. There are ok for subwoofers, but I honestly think that it is ridiculous to use a Class-D amplifier in a high end studio monitor.

In short, Class-D amps are more efficient but are only good for low frequencies applications like subwoofer amplification. Class-AB amps can be used full range amplification i.e from 20Hz – 20kHz. Class-D amps cannot be used on highs frequency response because they only produce square waves because of the technology involved, so they will make your highs sound lifeless and tinny. Class-AB amplifiers produce full variable signals and can capture subtle nuances better, sound warmer and generally have more depth in their sound.

CONTROLS

Z-2300: The control pod of the Z-2300 is quite simple, minimalistic & functional, 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.

DRASTIC MEASURES TAKEN TO CUT COST

Logitech have gone a whole way to reduce cost of the hardware in Z-623 in comparison to Z-2300.
1) The subwoofer is smaller & lighter with thinner wall thickness and no silver/black design. Saves cost.
2) The bass driver is smaller by an inch & have smaller magnet. Saves cost.
3) Jump from Class-AB amplifiers to Class-D with much less power. Saves cost.
4) Switching power supply instead of toroidal transformer. Saves cost.
5) No heat sink at the back of the subwoofer. Saves cost.
6) No master power switch & external fuse on the subwoofer. Saves cost.
7) Much thinner & shorter wires. Saves cost.
8) Satellites are ugly and use black plastic instead of glossy silver/black design with mesh cover of Z-2300 satellites. Saves cost.
9) Integrated controls with right satellite instead of separate control pod. Saves cost.

REPAIRING

No doubt that Logitech produces speaker system with excellent built quality that are built to last for decades. But at least for electronic components like speaker sets nothing is for sure. And also remember that Logitech will provide support for the initial 2 years, after that there will be no support. So what happens when:

1) Bass driver blows: Since Z-2300 uses an industry standard 8 inch bass driver, you can find a hundred speaker companies out there to provide a 8 inch bass driver that fits into the Z-2300 subwoofer assembly. Check YouTube & you will find a hundred examples out there. 

Since Z-623 uses manufacture specific & odd sized 7 inch bass driver, forget about getting it replaced with a new one. So, you end up with a dead system. 

2) Amplifier Module: Class-AB amplifier modules found in Z-2300 are very easy to repair, any local repairing shop will do that for you, and the amplifier chips and components are readily available in the market for replacement. Same goes for Z-2300 toroidal transformer. 

Z-623 uses Class-D amplifiers & switching power supplies which are piles of crap after they are broken or dead. Just think when your PC’s power supply (SMPS) blows out you do not repair them since they require costly machinery for repairment & also the parts are not readily available. So you just buy another SMPS and fit into your PC. 

The problem with Z-623 is it does not use a industry standard SMPS as your PC but are manufacture specific, which the manufacturer (Logitech) will not provide to you after 2 years. So, you end up with a dead system. 

3) Satellites stop working: Z-2300 uses two satellites that are connected to the subwoofer with industry standard RCA input cables. Suppose one of them stops working, I can buy a dozen pair of bookshelf speakers having RCA input cables available in the market and directly plug to the Z-2300. All I have check is that each bookshelf can handle at least 40W RMS of power & are rated at 8 ohms. 

As for Z-623 you can do that for the left satellite as it comes with RCA cabling but not the right one which comes with manufacture specific D-Sub plug. Also, the satellite speaker impedance rating is 6 ohms which is kind of odd, since 4 & 8 ohms are readily available in the market. So, if the right satellite goes you end up with a dead set.

PERFORMANCE

Z-623 performs admirably well in movies & games. It also performs well in music. It may not have the same hardware architecture of Z-2300, but Logitech engineers have made sure that Z-623 possesses the genes of Z-2300. It definitely has the upper hand over its opponents namely Altec Lansing MX-6021, Sony SRS DB-500, Edifier S530 & Creative Gigaworks T3 in terms of performance. No doubt Z-623 is the winner among the current heard and also the best of the lot in terms of performance/ price ratio.

But when you put the Z-2300 in the above equation, everything falls loose. Z-2300 is like a lion among a herd of cattle’s named Z-623, DB-500, S530 & T3.

1) None of the above sets have the power output capability of Z-2300. Z-2300 is the loudest of the lot and makes the opposition eat the dust.

2) Z-2300 has wonderful power reserve in the amplifier & thus do not distort even at full volume. Z-623 & all the other sets distorts at full volume.

3) In terms of music representation Z-2300 is second to none. Since Z-2300 uses Class-AB amplifiers, the sound produced by Z-2300 is more natural, very well defined & represents the true analog nature of the human voice. Both male & female voices are excellently represented in Z-2300. In contrast Z-623’s Class-D amplifier lacks a little bit of the natural feel & warmth in the sound as found in Z-2300 and represents more that of MX-6021 & DB-500 in their sound characteristics. The subwoofer has tight bass but the overall bass of the Z-623 is not well defined. A system with Class-AB amplifiers (as in Z-2300) will produce bass which is a little less deeper than a Class-D of Z-623, but the bass will be much more defined & accurate and also feel more natural & real.

For example, playing the track "Chant" of the band Foreplay, I noticed that the kick drums of that track produce "boom boom boom" on the Z-623. Playing the same track on Z-2300, the kick drums sounded "booouuumm booouuumm booouuumm" which happens to be the actual sound of kick drums. In contrast, Z-623 bass goes a little deeper but is less natural & neutral. Audiophiles will definitely choose Z-2300 over Z-623 for these single criteria. 

4) In movies & games which do not contain the subtle nuisances of complicated music reproduction, Z-623 is right up there with Z-2300. If you just want a speaker set for movies & games you will be blown out with the performance levels these Z-623 babies can achieve.

VERDICT

Z-2300 is hitting the end of the 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. If it not available then only greet the new champ of the block, Logitech Z-623.

Logi Rook
RishiGuru
Posts: 95
Registered: ‎09-29-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

A request to Logitech Forum administrators, please do not delete this thread from this forum since, this are my personal views, thoughts & findings. I think you all will respect the personal views of every member.


If i am wrong in any of my above views or thoughts, kindly rectifiy me and provide the reason why I am wrong. I will be glad to accept it. Thanks.

Logi Apprentice
zcinema123
Posts: 210
Registered: ‎05-28-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

[ Edited ]

with the Z-Cinema there is this ~30hz crossover limit on the subwoofer. anything below will not be produced. if you run a frequency test tone to confirm, the subwoofer will not slam as it should.

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easy way to tell is with playing bass i love you tone. there is this 10-15hz tone that will make your subwoofer jumps. after checking with youtube it seems that Z2300, Z Cinema and even Z5500 have these filter enabled. can you check whether the Z2300 has this crossover filter because it's irritating in the Z Cinema.

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it isn't a big deal if you've not heard those frequencies before. but once you're used to them it's unpleasant to hear them completely missing.

Logi Rook
RishiGuru
Posts: 95
Registered: ‎09-29-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

Z-Cinema cannot go as low down in the frequency range as Z-2300

 

Z-Cinema: 40Hz - 20kHz  [8 inch bass driver]

 

Z-2300: 35Hz - 20kHz   [8 inch bass driver]

 

Z-5500: 33Hz - 20kHz   [10 inch bass driver]

Logi Apprentice
zcinema123
Posts: 210
Registered: ‎05-28-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

specification sheet only mentions the "effective response" of the subwoofer. perhaps Z Cinema can only produce significant amount of bass around 40hz, i agree. but anything below 35hz is blocked, which means there are some lower bass missing. beside, the effective response varies in room placement, especially when used in small, medium or large room.

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to confirm this, run a frequency tone software and set it to let say 10-30hz (careful with the volume) and see that with Z Cinema the subwoofer did not slam at all as it should. With other speakers, even cheap or expensive speakers they should slam regardless whether the frequencies can be heard.

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at first i thought this limit only applies to Z Cinema. but thanks to YouTube, if you look up 'bass i love you' being played in any subwoofer brand, regardless cheap or expensive, you will see that Z Cinema or Z2300 have the limit enabled, that prevent it from playing anything below ~35hz, by looking at the certain tone that the subwoofer did not slam.

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it's a big deal because i believe Z Cinema and Z2300 can still provide some bass (not so much) around 30hz. 35hz is just too early to limit. if they set it to 20hz instead it would be much better since Z2300 and Z Cinema have enough power.

Logi Rook
RishiGuru
Posts: 95
Registered: ‎09-29-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

[ Edited ]

You are right zcinema123. I downloaded a played tones of 50Hz, 40Hz, 35Hz, 30Hz, 25Hz, 20Hz.

 

Reactions of Z-2300 when playing the tones:

 

50Hz -> Ultra Loud subwoofer with heaven broke loose diaphragm movement from the bass driver

 

40Hz -> Ultra Loud subwoofer with heaven broke loose diaphragm movement from the bass driver

 

35Hz -> Loud subwoofer with a lot of diaphragm movement from the bass driver

 

30Hz -> Perceptible sound from the subwoofer with very little diaphragm movement of the bass driver

 

25Hz -> Whispering sound from the subwoofer with almost no diaphragm movement of the bass driver

 

20 Hz-> No sound from the subwoofer with no diaphragm movement of the bass driver

 

I can think of the following reasons as of why Z-2300 was blocked producing anything below 30Hz

 

1) The subwoofer enclosure is tuned to produce maximum loudness at around 45-55Hz region . Maybe going any lower may have an effect on the tuning.

 

2) The 8 inch bass driver of Z-2300 have a nominal power input rating of  70W where as the amplifier is capable to deliver 120W to the bass driver. Since, tones between 20 - 30 Hz  will produce maximum strain on the bass driver, the diaphragm of the driver will be moving like hell and, say at 100W RMS may result in tear or burnt voice coil, they have implemented the safety feature.

 

This are all my assumptions. I may be wrong. 

Logi Apprentice
zcinema123
Posts: 210
Registered: ‎05-28-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

well, that's what bothering me with the Z Cinema. please don't get me wrong, i am very happy with the Z Cinema. i think for the price i paid (half of the original price) it is worth it. however i am slightly disappointed with the subwoofer response.

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all i can think is Logitech install a filter as a safety measure so reckless people who play huge amount of bass tones doesn't blow their subwoofer or amp. but limiting somewhere near 35hz is too early, if they set it around 20hz it would be more appropriate, since around 30hz the z cinema subwoofer, i believe can still output little bass. mind that little is better than none.

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i wonder if anything in the circuit can be removed to bypass this filter. however upon seeing Z Cinema board, i don't think i caught anything suspicious yet, since it's rather complex to analyze.

Logi Rook
RishiGuru
Posts: 95
Registered: ‎09-29-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

Definitely it would have been better if the frequency response of Z-2300 & Z-Cinema would have covered the entire spectrum, i.e. 20Hz - 20kHz. But sadly, that is not the case. 

 

But can you name a single multimedia speaker system within $500 that can do so? I cannot find one. Can you?

Logi Apprentice
zcinema123
Posts: 210
Registered: ‎05-28-2010

Re: Is Logitech Z-623 the true successor of Logitech Z-2300?

i don't think anything for PC can go as low as 20hz. you will have to find a HT sub to get 20hz in reasonable dB.