 Without marketing, audio would not be possible at the quality level it is now. Marketing explains why a product is worth spending money on. It therefore is important to understand what marketing does and how to set up a defense shield against it. Let's start with my frustration. I don't like going to large consumer electronic shows. Not only since they offer a far wider product range that I am professionally interested in, like TVs, smartphones, tablets and the like. Sometimes even kitchen appliances, like microwaves. But that's not the main reason. It's the press conferences where large electronic companies declare they are the biggest, the best and have the biggest turnover. It's already quite some time since I visited the Funkausstellung in Berlin. Years ago there were three companies that each declared to be the biggest player in the TV market. They each used turnover figures of the screen sizes they were the biggest in during a given period. Each using another period of course. Simply analyzing the press kits afterwards made it all clear. By the way, you are not supposed to ask questions about it during the press conference, at least if you want to be invited the next time. Luckily this is different on the audio shows you and I visit. Simply because the audio market is too limited to be able to afford professional marketeers. But that doesn't mean everything a manufacturer or distributor in our market uses as arguments in favor of their products is true. Let's have some examples. Let's start with an example I have often mentioned before. DAC chips. Many manufacturers nowadays mention what chip is used in their product to do the digital to analog conversion. But today, judged by ear, differences between good DAC chips are so small that other design choices are at least as important if not more important. More and more DAC chips offer the possibility to have reconstruction filters done by an external microprocessor. The quality of the filter algorithms often have a far greater impact on the sound quality. And the power of the microprocessors also has to do with how powerful the filter algorithms can be. So if you compare two DACs with different DAC chips, don't think the difference is due to the choice in chip alone. Not that two DACs that use the same DAC chip sound the same either. Next to the filter algorithms, things like circuit board design, clock oscillator and other component choices have their influence. Let's look at the clock oscillator. Everything digital works in stepped processes. Like walking is a stepped process, alternating one leg for the other, resulting in a forward motion. Digital audio, as used for CD, uses 44100 steps per second to generate a sequence of voltages as they were measured during recording. If when walking, the steps are not regular, your forward motion won't be fluent. The same goes for digital audio. If those steps are not extremely regular, the music will not be fluent. One of the two major weaknesses of poorly built digital audio equipment. Extremely regular here means a few microseconds. A microsecond is one millionth of a second. It is the task of the clock oscillator to make the audio gear step every 44100 of a second with the precision of at least a few millions of a second. To achieve that, a precision of the clock oscillator of a few picoseconds is minimum. A few trillions of a second. Betadags now use clocks with femtosecond precision. A femtosecond is a quadrillionth or one millionth of a billionth of a second. Some say that our hearing is incapable of hearing such speed differences. But that's a mistake. It's not about speed differences, it's about the accuracy with which the waveform is reconstructed. And thus the distortion of the signal in time. And watch out, a so called femtoclock can have one or 999 femtosecond precision. So the term is relatively meaningless. And that's apart from the fact that the character of the deviation from perfect timing is important too. Then there are several ways to make a crystal oscillator generate more precise clock signals. Often temperature compensated crystal oscillators, TCXOs for short, are mentioned where a circuit tries to keep the clock as stable as possible over time. Even oven controlled crystal oscillators, OCXO for short, are mentioned where the crystal is encapsulated together with a small heat generating element. There are even oscillators used that are linked to the atom clock. In fact, these ways of controlling the oscillator's precision are aimed at long term variations, as where with audio we are interested in extremely high precision over short term. So I wonder if those oscillators really provide a better sound quality. Some high end manufacturers simply measure the precision of each crystal oscillator and only use the best ones. The other ones are rejected or used in cheaper products. This is a rather expensive way of working and only used when very high specs have to be met. A simple crystal oscillator could be had for 50 cents. Very high crystal oscillators cost tens of dollars. That alone means that a 200 euro DAC can't have the same quality as a 2000 euro DAC. If you use a separate streamer and DAC, the clocks in both plus the connection between the two define the quality. And the digital interfacing again can be subject of false promises. In certain circles on the internet, the I2S interface is believed to be the best digital interface between the source and the DAC. And thus that the DAC with an I2S interface is better than one without. That can be the case and will be in a number of cases. The interface became popular because a high end brand introduced very well designed equipment using I2S. They consequently promoted since it then was a unique technique with very good results. So the internet understood I2S was the thing to have and since simple implementation of I2S is relatively cheap, other manufacturers started to implement it as well. But I2S stands for IIS or Inter Integrated Circuit Sound. It is a standard for sending digital audio signals between chips within a device. It was not intended to be used between devices so there is no standard for this use. Some manufacturers use RJ45 network cabling, others 3 or 4 BNC cables or 9 pin RS232C cabling and again others use an HDMI cable. I must say that HDMI cables make a lot of sense since they are readily available and offer very high bandwidth, which is always good for digital connections. The problem is that not all manufacturers use the same pin out. So always check if the two devices you want to connect using I2S over HDMI cable are compatible. The reason for those high end manufacturers to choose I2S to interface the devices is that it uses separate lines for the clock signal, word select that indicates if the data is for the left or the right channel and sequentially a left and right audio data. That makes it easier for the receiving device to link to the clock of the sending device. But connecting two digital devices over I2S is not as easy as it looks. Chips outputting I2S will not necessarily match the impedance of the cable or cables used. So a driver chip might be needed adding to the cost and complexity. The sending and receiving chips need instant voltages and very low pollution on the power lines to perform very good. See my video why digital circuits influence the sound quality, if you want to know more about this. Like the AES-3 interfaces I2S is isogranous, so the quality of the clock signal in the sending device defines the jitter later on. Which brings us back to the clock oscillators and the quality of the circuit board design and the power supply. It can all be done good, very good even, but not for little money, not even in China. Other digital interfaces like AES, EBU, SPDIF and USB audio class 2 might outperform I2S if they are better implemented. Comparable things play a role in amplifiers. Here, all other things be in equal, amplifier architecture is often used. Class A designs are well known for their sound quality. They have no crossover distortion but also relatively low output power while consuming a lot of power and thus generating a lot of heat. Heat can affect longevity. Class AB always has some crossover distortion, depending on the design this can be rather low but in poor designs it can be high, so the sound quality can vary between very good to rather poor. Class D has enormous control over bass, very low power consumption and thus low heat development but poor designs can sound classy, nasal and unnatural. Class G works with the dual power range, offering a Class A-like sound character at normal listening levels and Class AB-like sound character at high listening levels. It might be clear that Class G is more complex to build and thus will cost more. Again, not all Class A amps are a good choice. In the past there have been Class A amps that after a few years broke down because of the influence of heat on capacitors and transistors. The other classes also know their better and worse designs each with its own problems. Many manufacturers use the amplifier's class often as a proof of quality. In the beginning of Class D, when the sound quality overall still was poor, manufacturers proudly stated that their amp was Class AB. Products for the real connoisseur would advertise their amps as having Class A. Now that Class D is more economical and has improved sound quality, Class D often is advertised emphasizing the fantastic bass control. In reality, I know amps in any class that I wouldn't mind owning. It's better to check if the amp and the speakers go well together, for that's more important. Output power is another thing that can be used for marketing. Some manufacturers specify power output at 3% distortion and 1000 Hz in 8 ohms. That way, the power supply need not to be large and thus saves money. But there might be poor bass control and micro-dynamics. A way around that is using a switch mode power supply that can offer very good results provided the power supply is very well designed and not the cheap Chinese ready-to-use modules used in low-end products. For those can deliver good bass response but will have poor mids and highs. If the power output is specified for 20 to 20,000 Hz, chances are sound quality is better but again no guarantee for a real good sound. For it might be able to survive a distortion measurement but is it able to deliver current for a heavy bass signal or current demanding speaker? Again, listening to the amp in combination with your speakers of choice is the best advice. Speaking of speakers, also with speakers there are many urban legends. To name a few, ported systems have poor lows, transmission lines have slow lows, closed boxes sound boring, electrostatics are far better in transients and so on. For the mid-range and the tweeters there are all kinds of beliefs too. Let's take the electrostatic speaker as an example. It is supposed to be also fast because of the ultra-thin membrane that produces the sound and therefore they should be way better than electrodynamic speakers. I have had several electrostatic speakers for in total almost three decades. Quot ESL 63s, Vermaider 4s and two types of Martin Logan. They all had roughly the same disadvantage. They needed electro-dynamic woofers to be full bandwidth and they suffer from dynamic compression in various degrees. For when the membrane moves to the front or back to set the air in motion, the tension on the membrane increases. Magnetostat suffer from this too. Plus most panel loudspeakers suffer from lobing. You can easily hear this by playing music over the system and moving your hand to the sides. You will hear a phase coloration of the sound. No problem if you are on the hot spot and sit still of course. By the way, the electrostats I own suffered less from this due to their constructions. The Quots had a separate central panel for the mids and highs. The Vermaider Quots only had a small electrostatic panel that only worked for 500 Hz upwards while the electrodynamic speaker covered all below 500 Hz. The Martin Logan's had curved electrostatics for mids and highs and electrodynamic lows. To be true, any speaker system, in fact any audio system, is a compromise where the price is the strongest factor. But also the technical design always is a compromise. Of course there are better and worse designs, but there are loads of better designs and they can be based on all kinds of working principles. I refuse to review bad designs and have good reasons for that. First, it is of no use to you when I tell you what not to buy. I rather advance you well designed products. And second, I find reviewing poorly performing products highly frustrating. If you want good music reproduction and want to spend some money, watch and read reviews by me and others. Furthermore, watch my videos on how to select a stereo and how to listen part 1 and 2. Then try to visit a dealer on a weekday, making a point that if you can, and have possible solutions for you, demonstrate it. Use the music you play to enjoy music, not the air candy you hear in high-fives shops and shows. And trust your ears. If you find it good sounding, go for it. Watch your feet, if at least one taps the rhythm, you can't be far off. Which brings me to the end of this program. See you next Friday at 5 p.m. Central European time. If you don't want to miss that, subscribe to my channel or follow me on the social media so you will be informed when new videos are out. Help me reach even more people by giving this video a thumb up or link to this video on the social media. It is much appreciated. Many thanks to those viewers that support this channel financially. It keeps me independent and lets me improve the channel further. If that makes you feel like supporting my work too, the links are in the comments below this video on YouTube. I am Hans Beekhuyzen, thank you for watching and see you in the next show or on the HBproject.com. And whatever you do, enjoy the music.