Explorations in Audio

High Fidelity

What does music sound like?

I think everyone will agree that there is something special about listening to a live music performance, whether this be in a recording studio, a Jazz club, or a live concert. The sound of instruments being played mixes with the ambience of location to provide that unmistakable sensation that anything is possible. In High Fidelity we attempt to keep as much of this authentic sensation alive as possible, but, regardless of how much money we spend, more often than not, the result we achieve in our homes is much less. However, this does not necessarily mean that our system as such is at fault or that we cannot afford what it takes to preserve the musicality of the original event.

In a typical household environment many factors will have a marked influence on the quality of sound that have little or nothing to do with the equipment itself, but rather with how it is connected, where it is placed, and with the characteristics of the room. The following steps are intended to provide an overview of the factors involved in maintaining sonic integrity, from the source of the system’s energy all the way to energizing the room.

From Power to Speaker

  • 1. The Power Source

    1. The Power Source

    3/28/2020

    Author: Karsten Hein

    Category: High Fidelity

    Since the basis of any system is electric power, this is a good place to start setting up our system. Depending on the time and effort we are willing to invest, we might start by having a slow-blowing fuse installed and running a dedicated power mains from the central fuse cabinet to our system.

    The distortion to be found on a power grid can be measured and shown. It comes from many sources, such as trailing edge dimmers and transformers found on LED lights, from local industry, from refrigerator motors, from switches, WiFi networks etc.

    Power source

    The picture shows measurements made in our apartment. The spikes show the level of distortion and interference as described above. Since we are renting, I did not have the luxury of running a dedicated cable, but I did locate the socket with the least distortion, and I am running a 2.5mm solid core house installation wire from there. This type of wire is not meant to be moved around, I therefore installed a cable duct to keep it in position and protect it from wear.


  • 2. Power distribution

    2. Power distribution

    4/25/2020

    Author: Karsten Hein

    Category: High Fidelity

    Once we have located the cleanest possible power source for our HiFi system, the next challenge will be the distribution of this power to an array of audio devices. Separate units do not necessarily 'sound better' than their high quality combined equivalents, yet, separates have the advantage of allowing for some 'later stage adjustments' when calibrating a system to the room, the preferred style of music, and individual taste without the use of attenuators.

    The units may be: a CD player and turntable, a DAC, an audio streamer, a pre-amp, a power amp, and possibly more. A dedicated audio power strip will be designed to minimise differences in electric potentials between the devices, thus leading to a more even flow of current. Such power strips come in many shapes and price ranges.

    For my own low budget setup I bought a used Audioplan PowerStar 'cookie jar' distributor and had 3m of shielded 2.5mm Lapp Ölflex power cord attached to this. This is nicely fitted with a gold plated heavy duty power plug.

    From my own experience, all cables, even power cables, will need some time to run in before showing their full sonic potential. I have never connected a new cable that did not drastically change its effect on the music within the first three days of playing.

    Next to proper phasing, the precise position of a plug in relation to the other components on the power strip may make a big sonic difference. The traditional order is: amp, pre-amp, turntable, and the rest, with digital as far away as possible. However, since there is no definite rule, we have no other choice but to test different combinations ourselves.


  • 3. Power cords

    3. Power cords

    4/26/2020

    Author: Karsten Hein

    Category: High Fidelity

    Coming from a dedicated power strip or directly from a wall socket, our clean power will need to be forwarded to each of the HiFi units, at a typical distance of less than 1.5m. Although this distance is relatively small when compared to the house installation, the sonic difference between a standard supply cord and one that has been engineered for audio usage is quite enormous.

    Especially to amps and preamps, the power cord is of such importance to the overall sound integrity that we are well advised to invest at least 10% of the unit price on the power plugs and cord. Typical HiFi cords will be designed on the basis of 2.5mm diameter wires. However, diameter is not everything. There are cords of smaller diameter with excellent sonic characteristics.

    On my own vintage units not all cords are removable. I upgraded the cords on the amps (during recap) as well as on the high-voltage transformers of the electrostatic speakers, and I made sure that the general power strip is also equipped with an excellent cord. - Especially on the amps, the new cords have greatly contributed to the system's improved musicality.


  • 4. Power filtering

    4. Power filtering

    11/23/2020

    Author: Karsten Hein

    Category: High Fidelity

    The better our system is designed, the more it will reveal flaws in the electric current. HF interference is such a flaw and can be found to various degrees in all households environments. Interference comes from modern lighting, communication equipment, and from many other sources.

    HF interference will destroy the sonic integrity of our system right from the source, e.g. by saturating the iron core of the power transformers. The acoustic effect will be a subtle leaning of the system towards harshness, technicality, and a tin-like ringing in the highs leading to early listening fatigue.

    Power polisher

    While there are many pricy solutions to combat the issue, there are two relatively affordable interventions: ferrite clamps and shunt filters (also called power conditioner or noise trap). I have achieved excellent results by placing one ferrite clamp on each power cord and one clamp on the power strip lead. For maximum effect, all ferrite clamps are mounted in a position just before the cable enters the housing. In addition, a power conditioner is plugged into the power strip.


  • 5. Phase alignment

    5. Phase alignment

    4/26/2020

    Author: Karsten Hein

    Category: High Fidelity

    In HiFi forums it is often suggested that the polarity of a 240V plug should not matter, because the polarity is oscillating at 50Hz. However, this is not the whole truth, as only the phase oscillates while the other remains neutral. In many countries, such as the US and Britain, an inversion of the poles is prevented wherever necessary through the use of directional plugs, either through a ground prong (UK) or through one pole being larger (US). The question of whether polarity matters is therefore essentially a German one, and as such, it will never go away.

    There are many ways in which to determine the correct polarity of a unit’s plug. Oehlbach suggests we use their ‘Phaser’, others favour extensive measurements with the unit being turned on and off. Regardless of the method employed, the first step will be to use a phase tester, usually a screwdriver, and to check and mark the phase on the outlet socket. When using a power strip for distribution, the phase should be marked here as well, this can be done with a white or red marker or with adhesive dots, etc.

    Although I have used the Oehlbach Phaser at times, I have found the most effective method to be trial and error, using my own ears. To do so, I took an empty power strip and plugged in the minimum units I need to play music, e.g. turntable, pre-amp, amp. If your phono preamp is not located inside your turntable but in your pre-amp, the polarity of the turntable does not matter, because the audio signal path is passive. This way I only had two plugs to phase: pre-amp and amp. This limits the number of combinations.

    What to listen for: When phase alignment is done poorly, the music sticks to the speakers and the phantom center (the middle position resulting from mono signals in the recording, usually the voice) will be off. When phase alignment is done correctly, the music will extend into the room, with the phantom center being as discernible as a third speaker. Do the same for each new unit you bring in, until you reach this effect. This is called phasing your system and is an interesting stage of the setup that can take some time getting used to. Once you have it right, there is no going back.

    When phasing a single unit, such as a receiver, with no other units attached during listening, the effect of phasing might be less pronounced. Phasing mostly has to do with differences in electric potential between devices.


  • 6. Pre-amplification

    6. Pre-amplification

    3/28/2020

    Author: Karsten Hein

    Category: High Fidelity

    A pre-amplifier can well be considered the heart of our system. Since many pre-amps will feature a built-in phono stage, for MM, MC, or both, there is some amplification involved, however, the term describes more its position before the amplifier than its calling. Pre-amps generally serve as a hub to rout music signals from multiple sources to a single power amplifier. All preamps add a sonic signature, and, because of their central position, this signature will make or break a good system.

    It therefore makes sense to choose our preamp well, and there are some pointers to look out for: 1. Signal integrity may be corrupted when running though potentiometers, hence, audiophile units will rarely feature bass, treble, and other attenuators. 2. Power supplies may inject interference into the signal. Many units therefore place the power supply in a separate housing. 3. Thin conductor tracks on the circuit board may cost speed and dynamics. 4. 2D circuit board layouts may pick up interference. High End units will often have a greater degree of direct wiring.

    For my own system I chose a pre-amp from a lesser-known US manufacturer who have been constructing their DB Systems DB1 with the power supply DB2 from the 1970s until today with only minor changes. The unit is built under consideration of the four pointers mentioned above and produces a remarkably natural and inviting midrange with overall extremely low distortion. It can feed two amplifiers, a very convenient feature that I have at times made use of, e.g. for bi-amping hybrid speakers.


  • 7. Interconnects

    7. Interconnects

    3/28/2020

    Author: Karsten Hein

    Category: High Fidelity

    Audio signals are usually transmitted between the units by means of wires. The plugs may range from 5-pin DIN via RCA and jack-plug to XLR balanced studio standard. For home and even High End audio designs, the most common type of plug is still the RCA/cinch coupling. This type of connection has some practical advantages, e.g. no converters needed, but it also features some inherent design flaws for optimal signal transduction. Optical connection can be made via Toslink (light pulse). Although widely available, this is not commonly used by audiophiles, as the music often becomes dull, and good signal converters are rare.

    As a result of all this, RCAs interconnects have long since become significant components in their own right, because, depending on the materials used in the design of cables and plugs, the sonic character of the system will be influenced by them. From detailed to confined, from dynamic to dull, our system’s musical signature will be shaped by its compatibility with the interconnects used between source and pre-amp and between pre-amp and power amplifier.

    In my own tests I have found that no two interconnects create the same sonic effect and that the preference of one interconnect’s sonic characteristics over another greatly depends on the electronic environment that it is used in. This means: an interconnect that has been found to be beneficial for phono to preamp connections may well perform poorly in all other positions in our system. The phono to preamp connection is a very special one in which much attention needs to be placed on shielding to avoid humming and other interference.

    Looking at our own system, it turns out that every position is a special one. A CD player for instance may benefit from a braided wire (e.g. Western Electric, Kimber, etc.) instead of a solid shield, whereas a 5-pin to cinch (e.g. Sommer Cable) is not misplaced on an FM radio tuner. I have learned that the best way of finding the most suitable interconnect for a position is through trial and error. All interconnects shown in the picture have one thing in common: they do not fit my system in its current stage and have been replaced.

    The interconnects from left to right are: 1. Neutrik NF2 (on Kimber Tonik); 2. Sommer Albedo; 3. Fadel Art IC4; 4. Wireworld Composilex 2. - Of these, only the Kimber would be considered more than Mid-Fi.

    Plugs and wires individually, and especially in their combination, show different properties in terms of their resistance, capacitance, and inductance. Of the three properties, resistance is deemed to be the most significant, yet the precise combination of all three properties, over the full span of frequencies from at least 10-30.000 Hz, in the end creates the unique sonic signature of an interconnect.

    In September 2019, Rainer Langlitz and I tested the resistance, capacitance, and inductance of four interconnects of different manufacturers at just one frequency (1,000 Hz) and found each one to be different from the others. Measuring the full band of frequencies would most likely have revealed each interconnect’s unique signature that sets it apart from the rest. At the time we did not have the equipment to conduct a more thorough investigation.

    Quality interconnects will usually show an indication of the direction in which they should be connected. This is usually the direction in which the steel was rolled and the wire was produced. We can confirm the importance of the direction by inverting only one channel. If we have set up our system according to steps 1-7, the phantom center should be off during the inversion.


  • 8. Power Amplification

    8. Power Amplification

    11/23/2020

    Author: Karsten Hein

    Category: High Fidelity

    Our pre-amplifier passes the signal it receives from the music source through to the ‘power amplifier’. If this process is combined into a single unit, this is simply called ‘amplifier’. If a tuner is added in the same housing, the unit becomes a ‘receiver’. While these combined units are often cheaper and more convenient, they also limit the options in customising our system, e.g. when changing to new speakers. - Without doubt, there are great units to be found in either discipline.

    A power amplifier takes the relatively weak electrical current coming from the pre-amp and uses it to operate a regulator that controls a high current coming from the power grid. The regulator can be in the form of a transistor or a tube, or in that of a digital switch. Both transistors and tubes radiate lots of heat during operation. Tubes mostly because of their internal heating, and transistors because of their relatively slow adjusting of a high energy source. Classic transistors are round and shiny looking, similar to tubes.

    An amplifier needs a strong, low radiation transformer (often toroidal or encapsulated) that delivers both the operating and the amplification current, and lots of excess energy that is stored in the large capacitors (similar to ultrafast batteries) to provide music burst power that the power grid could not otherwise provide fast enough. It also needs one operating board and at least one transistor (or similar) per channel, usually mounted on large heat sinks for cooling.

    From the combination of these parts results the amplifier’s power rating. This is usually provided in two numbers: watts & ohms. The watts is the ability to provide power into a load resistance that is rated in ohms. Theoretically, when you lower the load resistance on the side of the speaker, the ability to deliver watts on the side of the amplifier increases. There is a limit to this, however, because reduced load also means more back current to the amplifier which at some point either becomes unstable or overheats and dies, perhaps taking the speakers with it.

    When I first looked at the subject of power amplifiers for my system, I was surprised that some of the most highly esteemed amp designs displayed great simplicity in terms of both: components and layout. Having had the privilege to sonically compare some older with more modern designs, I am currently very pleased with the well balanced sound of the 1989 B&K ST140 amplifier that I purchased from a member of the local audiophile community. The amp's ability to deliver into a 2 ohms load was among my considerations.


  • 9. Speaker Cables

    9. Speaker Cables

    11/23/2020

    Author: Karsten Hein

    Category: High Fidelity

    We use speaker cables to connect the output stage of our receiver, amplifier, or power amp to our set of loudspeakers. While this sounds to be an easy enough task to perform, there are some considerations to be made to assure the best type of connection within our budget. As with all wire connections, there are the following specifications to be considered: resistance, capacitance, and inductance. Of these three properties, resistance is found to be the most significant, yet the precise combination of all three properties over the full span of frequencies will create the unique sonic signature of a speaker cable.

    To assure for low resistance, speaker cables should be as short as possible and of equal lengths. Ultimately, this means we will need to place our system between the speakers, with the speakers themselves placed as close together as possible, and as wide apart as acoustically necessary, considering the room and listening position.

    Since corrosion is the enemy of any connection, bare wire connections are not common among audiophile listeners. Instead of bare wire, two types of terminations are commonly used: banana plugs or spades. Mostly, the termination is soldered onto the wires, using lead or silver as base material. Screw-on terminations often displace the wire material and, with time, may lead to a poor connection. Low mass terminations, such as hollow bananas or thin spades, usually offer superior musical imaging with increased fine dynamics when compared to their higher mass gold plated alternatives found in many High End shops.

    Cable designs often take into consideration the effects of interference on wires and the disparate characteristics of different strengths of wires. Kimber Cable, for example, braid their speaker wires and use different thicknesses of strands within a single cable, others may twist or externally shield their wires. Personally, I have found twisted tinned wires with beryllium hollow banana terminations to be the most musical in my systems. On the downside, tinned wires have some of the longest run-in times imaginable, with their full sonic potential taking 200+ hours of usage to unfold. Especially in the first few days, I did not find it easy to stay in the same room with them, given their at first poor sound balance. Just to compare: The run-in time for OFC copper cables is estimated at around 80 hours.


  • 10. Speaker terminals

    10. Speaker terminals

    6/1/2020

    Author: Karsten Hein

    Category: High Fidelity

    Most modern HiFi (mid-market to High End) speakers feature terminals equipped for the connection of two separate sets of speaker cables. This allows separate connections to be made to the tweeter (highs) and woofer (lows) drivers of each speaker. Such terminals usually come with a bridge between them to enable connections with a single cable. When the speaker terminals are driven with two separate cables, the bridge must first be taken out, and the configuration is called bi-wiring. When two amplifiers are used, e.g. one amp driving the tweeter and the other the woofer, this is called bi-amping.

    Bi-amping is for instance used when a low power tube amp is to drive the high to mid section, with a beefy solid state power amp driving the bass section. However, bi-amping presents the most difficult issues to solve in trying to maintain coherence and will prove to be inferior to a conventional setup, unless we really know how to professionally phase align and fine tune such systems. The more likely option is bi-wiring or using a single cable with a bridge.

    Of the three options mentioned above, I have had the most success bi-wiring with a single point of contact on the side of the amplifier. To do so, I had to design cables with two banana plugs on the side of the amp and four plugs on the side of the speaker. Of course, such cables can be bought preconfigured, but it is obviously not as much fun.

    The single point of contact on the side of the amplifier makes for excellent sonic cohesion. Bi-wiring on the side of the speaker, however, carries each driver’s back-current straight to the amp terminal, without affecting the other drivers. Ideally, the wires split apart directly from the banana plug connected to the amp, with the two cables running in parallel over the distance to the speaker. This also elegantly increases the diameter without sacrificing the responsiveness of a lower diameter wire.


  • 11. Turntables

    11. Turntables

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    I must confess that I am still a relative ‘newbie’ to the subject of turntables. Like most turntable owners around in the 80s, I was excited about the emergence of the new, super silent, digital technology that came in the shape of a shiny and more compact disc. And, honestly, at the affordable price range of an adolescent, the CD performed much better. I consequently sold my record player in the early 90s, never to look back until ... summer 2018, when we found a 1972 Philips 212 deck in our grandpa’s basement.

    Lots of time reading and experimenting has passed since then. The Philips needed a new belt, bracket, and cartridge. We lubricated the moving parts, upgraded the internal wiring, and changed the output terminal from 5-pin DIN to RCA/cinch sockets. We checked the platter speed, corrected the azimuth, as well as the offset and rake angle. We made sure that the turntable was placed on non-resonant footing and was level with the ground. The result is astounding, and for the first time, our turntable actually does sound more impressive than CD, if the record itself is of a good pressing. Since buying a well-engineered LP can can be a bit of a gamble, it is a good idea to share personal experience on sound quality, as I have started doing here.

    The Lenco shown here was our second project. Once famous as a well-built budget player with surprising sound quality, it arrived here in pretty poor condition. We have had to remove motor noise, bring in new blocks, and adjust the other parameters described above to uncover its potential. The investment of time and effort has not been in vain. For audiophile listening, turntables should not be underestimated.

    Note on cleaning vinyl: For the longest time I had massive issues with static charges and dust while playing my records, despite using a brush to clean them. My records would crackle and pop and sometimes even skip a groove as a result. I later learned that while one hand is doing the cleaning, the other needs to touch some sort of grounding. Usually, touching a metal part of the amp will be enough. When doing so, I can see the dust flying up to the brush and feel the static charge disappear. A small realisation with an impressive result.


  • 12. CD players

    12. CD players

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    The CD offers decent quality music in a compact digital format. It offers a 44.1kHz sampling rate at a depth of 16 bits per sample. The parameters were chosen to cover the full span of human hearing from 20Hz to 20kHz. While this should be enough to replicate most musical information in bits and bytes, in recent times, it is often produced using downsampling and/or bitrate reduction - e.g. when the master file is recorded at 192kHz sampling rate and a depth of 24bit, as is common in Jazz and Classical music. Attempts have since been made to increase the sampling rate and bit depths in formats such as SACD and BlueRay Audio, but these failed to reach a market that had already abandoned the high quality audio sector for high convenience audio, such as MP3 and music on demand services.

    It is not surprising then, that sales of vinyl records have recently again surpassed those of CD, the first time in a quarter of a century. With audiophile listeners flocking to fashionable high-res streaming services, ownership has become a rare privilege and is best celebrated and contrasted by the meticulous ritual of playing and storing vinyl. Yet, in midst of all this, there is still lots of fun to be had with CD players, as there is more to setting them up and extracting an audiophile experience from them than may first meet the eye.

    To have the most options, make sure that your CD player comes with a digital coax output in addition to the more common Toslink connector, as well as RCA/cinch, of course. The Denon DCD-1420 player shown below was rather pricy in 1989. A look inside shows that the parts used in its construction are of decent size, however, it also reveals that more could have been done in terms of power supply, shielding, tray design, etc. The player would most likely be considered mid-Fi by modern standards. One thing that I enjoy about it, is the fact that it is the only device for which I have a remote control. This means, I can pause and play back music as I please, without having to constantly get up. I would like to say that I can also skip between songs, but, because of its advanced age, the small task of skipping titles has long since become a giant leap of faith.


  • 13. Digital cables

    13. Digital cables

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    There are no absolutes in life, and knowledge is by far the biggest hindrance to continued learning. Because only if we challenge established beliefs can we be sure that they still hold true in our time. After all, the Bahamas were discovered in a period, when Europeans had decided that the earth was flat. Exploration needs a playful mindset that favours personal enterprise to established fear. The rewards can be quite bountiful, indeed.

    When I set out to purchase a digital cable, I wanted to make sure that the signal coming from the CD Player was conveyed to the DAC in as pure a fashion as possible. I ordered a high quality fibre optics Toslink connector, as well as one four-times shielded cable of RCA/cinch coaxial standard for comparison. Prior to listening, I was convinced that the light pulse connection of the Toslink would present the purest result. To my surprise, this was not the case. Instead, the music sounded rather two-dimensional and flat, sticking to the speakers rather than being presented in the room. In the combination of Denon DCD 1420 and Cambridge DAC Magic, I found the Toslink connection to be less appealing to my ears than running the signal via the CD player’s own internal DAC. I did some research and found that this was a common phenomenon, possibly due to the quality of the two electro-optical converters involved.

    In contrast, the RCA/cinch coaxial connection sounded better than the internal DAC, right from the start, even with the volume adjusted to a lower level. The music was immediately more engaging. However, in longer listening sessions I noticed some unpleasantness in the highs and some issues with the phantom center which comes from mono signals in the recording and should be fairly wide in scope. Although digital signals are claimed to be free from interference, because of the way they are transmitted, the sonic signature of the issue was familiar to me from HF distortion, e.g. to be found on power cables. I consequently started experimenting with ferrite clamps. First, I attached one clamp and moved its position along the cable, looking for sonic changes. Although I had some better and some worse results, none was actually pleasing. I then brought in a second ferrite, and, placing them both on opposite ends, finally had the sonic coherence that I had previously been missing.

    The picture below shows a four-times shielded cable of RCA/cinch coaxial standard that I confectioned with a Viablue cable sleeve and two ferrite clamps. The cable sleeve has not been attached for optical reasons. I found that larger ferrite clamps have a better effect on sound, but with their growing outer diameter, the inner diameter also became larger. The cable sleeve has helped me to bridge this gap. Considering the amount of building material in use, the fully confectioned cable is still very affordable, especially in comparison with ready-made solutions.


  • 14. DACs

    14. DACs

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    There certainly is ‘magic’ in a DAC, not just in a Cambridge Audio “DacMagic 100”. A DAC is needed to convert digital signals coming from a CD player, a streamer, a laptop or a PC, and possibly many other sources, into an analog signal that can be processed by an analog pre-amplifier or similar device. As the digital signal is an approximation of an analog signal, there are some calculations involved. Finally, there is some foresight and sonic calibration necessary in the analog segment of the DAC to match the DAC’s output stage with the receiving device.

    The magic comes into play, when we hook up our DAC to a high-quality CD player. Because in this setup both the bit depth and sampling rate of the medium are given facts. The question at hand being: Will the external DAC outperform the CD player’s internal DAC, and in which way? Granted, you probably have to be an audiophile nutter to enjoy this sort of challenge. But, boys will be boys, and that is arguably good as it is. Other people sit for hours to pull fish out of the water, only to throw them back in.

    There are better DACs than the Cambridge DAC shown here. However, it is good value for money and did receive a favourable review from Ken Rockwell which should mean something. This being our first DAC, the small investment seemed high enough at the time. The DAC offers two coaxial, one Toslink, and one USB socket. The USB processing, especially, is said to be among the best in the market. Hi-res audio processing is possible, up to 192kHz. Normally, the adventure would end here, but you can probably already guess that it won't.


  • 15. Power supplies

    15. Power supplies

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    Even experienced audiophiles will at times state that acoustic treatments to the room provide the most significant foundation for a HiFi system. However, while this surely can be a significant corner stone, I find that one small thing is overlooked in this statement, and that is the effect of power on our system. If I was to identify the most significant contribution to a system’s sound, power would be first on my list. If you take away the room, you will still hear sound, but if you take away the system’s power -

    In steps 1-5 of this forum, the significance of power on the sonic nature of our HiFi-system has been described at great length. It is not surprising, therefore, that internal and external power supplies will have a similar impact on a unit’s ability to perform. Although the amount of power needed at any given time is relatively small for most units, especially when listening at 70-80dB indoor volumes, a power supply’s ability to deliver ultra quick, resonance and interference free electricity in the end will make the difference between our system moving towards High End or remaining stuck in HiFi.

    A few weeks into listening to the Cambridge DAC, I noticed that the music’s highs seemed a bit tin-like and unrounded, e.g. on acoustic guitars, while the bottom end was lacking in natural punch and fullness, e.g. on lower piano keys. Later, while running some tests on the quality of electricity in our house, we noticed some regular spikes and general noise floor emanating from the switching of the Cambridge DAC’s external power supply, basically an unforgivable oversight for such an important part of our system. Therefore, against the manufacturer’s advice and warning, it was high time to make a change.

    The power supply shown below was brought in to replace the cheap plastic China-made trailing edge transformer that had been found to inject local distortion into the whole system. With the new power supply, the sonic signature of the DAC changed from edgy and light to smoother and more balanced. Low piano notes now have a more satisfying punch and noticeably slower decay, much like on a natural instrument.


  • 16. Loudspeakers

    16. Loudspeakers

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    It is probably fair to say that there has been a fascination with loudspeakers right from the very start. Not so much with the technology behind them, but simply due to the fact that they can reproduce sounds of familiar things without being the thing themselves. For example, a loudspeaker may reproduce the sound of breaking glass, without being made of glass or shattering in the process. It may reproduce the clanging of hard metal, without being made of metal or clanging against anything itself. And, most importantly, it can mimic the sound of voices and instruments, a discipline in which human ears are especially sensitive and therefore critical. Even on people with emerging hearing disabilities, the voice level frequencies are usually among the last to go.

    While attempting to sound natural and accurate in their reproduction of music, most types of loudspeaker are first and foremost entertainment devices, and as such, they need to be able to survive on the entertainment market. As our understanding of this market and our behaviour as consumers changes, so do the design choices made by the manufacturers. Loudspeakers today look rather different from those made in the seventies. While modern designs tend to be tall, slender and cool looking, their older cousins were often wider and stubbier with warm looking wood finishes. However, these are just the visible features and would be alright, if it was not for another trend, namely that of the infamous target group analysis.

    Let’s face it. Well-engineered speakers, and the electronics needed around them, are by no means cheap. Manufacturers are therefore facing a rather mature customer group that has the space, time, and available income to purchase up-market loudspeakers. If income tends to improve with age, sadly our hearing often does not. It could well be argued that the two curves are diametrically opposed. Hearing loss affects both our ability to discern high notes, as well as our sensitivity to low volumes. Consequently, in A/B comparisons, the speaker with the loudest high notes will, more often than not, get to enjoy the ride home. Sadly, this type of speaker will have a life-long imbalance when it comes to natural representation, an obvious weakness that all future owners will have to come to terms with.

    Many things can and will go wrong at the point of sale. The speaker that sounded great in the shop, might not sound so great when placed into our own living space and hooked up to our system. The room, the furniture in it, and the electric synergy with our existing components will all affect the impression of sound. If possible, loudspeakers should therefore be tested and compared at home. Some dealers will be supportive and make such testing possible, however, there is a natural limit to this, and we might feel pressured to make a choice. The other option is buying loudspeakers used. Provided that the speakers are not broken on purchase, they will either sound great or can be sold again, usually for a similar or even higher price.


  • 17. Spikes or absorbers

    17. Spikes or absorbers

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    When placing acoustic equipment in a room, there are many factors to be considered that will have an effect on our equipment’s ability to perform and on the specific sonic signature obtained. One such factor is the platform on which our equipment is positioned. In a perfect setup, desirable frequencies will be supported, while unwanted resonances will be reduced. The only question being: How can we distinguish between the two?

    Loudspeakers are the most obvious devices within a HiFi system from which both desirable frequencies and unwanted resonances are emitted. In many cases, loudspeakers are sold without the addition of a specific coupling to the ground, and this does make sense, as the manufacturer has no control over the environment in which their product is going to perform. While it is often suggested that loudspeakers should be placed on spikes, to improve their sound, spikes will have a very specific effect that will only work, if the conditions are right.

    For maximum frequency and resonance control, a loudspeaker should have a stable stand. To achieve this, the speaker’s weight is at best distributed between three or four couplings to the ground. If four couplings are used, at least one coupling must be height-adjustable to avoid wobbling. If three are used, they should be positioned relatively far apart to assure a stable stand. Among the many couplings conceivable, three types are the most common: spikes, anti-spikes, and absorbers.

    In our own listening environment, I had first positioned the speakers flat on the hardwood floor, using non-height-adjustable 1mm felt pads. The sound was solid, but high frequency resolution was poor. The introduction of height-adjustable spikes and coasters brought instant clarity and direction to the music, but it also destroyed some of the homogeneity. Consequently, for quite some time it seemed to me that I had to make a choice between a well-balanced sound and maximum clarity. The spikes coupled the speakers so well to the ground, that the hardwood itself was in resonance with the speaker. To decouple the speakers from the floor, different methods and materials will work, also depending on the desired listening volume


  • 18. Racks and resonances

    18. Racks and resonances

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    Resonances play an important role in placing acoustic equipment in a room, not only when dealing with loudspeakers, but also on the devices that are used to drive them. Where they occur, they negatively influence a unit’s ability to perform according to spec and thereby change the sonic characteristics of our whole listening experience. Well-designed HiFi racks will help to keep both resonances and electric interferences at bay, however, not every good looking HiFi rack is acoustically ideal (very few are). It therefore makes sense to have some basic understanding of the subject.

    A typical ‘old school’ HiFi system will probably consist of two or three sources, a pre-amp, and an amplifier. Each device is equipped with at least one power supply. Many high-quality power amplifiers will even have one large power supply per channel. In our current system, there is one power supply in the CD player, one on the DAC, one in the turntable, two in the pre-amp and two in the amplifier, bringing the total number to seven. Each power supply is humming at 50Hz. The low vibrations are affecting both the device itself and all adjacent devices. Other resonances result from city traffic, industrial activity, people walking nearby, household appliances, etc.

    Although it may be argued that all HiFi units will benefit from resonance free placement, some are especially prone to instability, such as turntables and CD players. On turntables, any physical impulse coming from outside or within will be layered onto the audio signal and lead to inaccuracies in playback. On CD players the effect is not much different. Although some people argue that digital signals either work or don’t work, the effect of resonances can be heard in sonic brightness and harshness. If you have ever had an ageing CD player that would on occasion grab a CD slightly off center, you are already familiar with the effect, as before a CD skips, the music first becomes thin and strained.


  • 19. Speaker position

    19. Speaker position

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    Since very few audiophiles will have the privilege of building a dedicated listening room around their set of loudspeakers, both speaker size and position will need to be adapted to the space available in the household. In many cases, the chosen listening room will need to serve other purposes that are of equal or greater importance. Typical rooms for placing HiFi equipment are: living rooms, studies, dining rooms, etc. Judging from my experience in forums, many typical man-caves are even located in the basement. Be that as it may, there are a few simple rules that will help to enhance the acoustics in any environment.

    Firstly, let’s get acquainted with the terminology: Seen from the listening position, the wall behind the speakers is called the front wall of the room. The wall behind us is the back wall, and usually there are two side walls to complete the room. As we have seen earlier, in ‘Spikes and absorbers’, speakers should be placed on a firm stand to prevent them from wobbling. The minimum distance to the front wall should be at 70cm, measured from the front of the speaker drivers to the front wall. The optimum distance should be at around 1/5th of the depth of the room. This means that on a five meter room, the speaker front should be placed at around 1,00 meter distance to the front wall.

    The distance to the side walls should not equal the distance to the front wall. This is measured from the speaker’s axis and should be at least at a ratio of 1:1.3. To minimise the effect of room modes, our ear’s listening position should also be at least 1/5 of the room’s depth clear of the back wall. Moving both speakers and listening position closer to the front and back walls will usually enhance lower frequencies. For optimal imaging and sound stage, the distance measured between the speakers and the distance from each speaker to the listening position should be at least the same, in order to form an equilateral triangle.

    When floor and ceiling do not provide a damping effect, any room can become quite hollow sounding. Placing a rug in front of the speakers will help take the edge off of the reflections. Very few speakers will sound well with their front aligned with the front wall, or toed in to stand on axis. Now is as good a time as ever to begin experimenting. What to listen for? If placed well, you will experience a seamless three-dimensional stage that has both depth and width extending beyond the physical position of the speakers. I am currently running two vintage systems, of which one is placed in the living room and the other in my office. In both cases, I have had to make some concessions to the multiple functions of the rooms. However, given some time and effort, I have managed to produce a quite realistic and wide stage impression that extends well beyond the speakers. I know that I could do better, if it were possible for me to move even further into the room. My current distances to the front walls are between 80cm and 90cm with a slight toe in, in both cases.


  • 20. Types of loudspeakers

    20. Types of loudspeakers

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    There are many different types of loudspeakers on the market. They range from horn-loaded designs to transmission lines, from 4-way via dual concentric to full-range. Each type has its own characteristic signature that will have benefits in some applications and disadvantages in others. To choose the best type of speakers for our lineup, we will need to consider the size of our listening room, as well as the types of music that our speakers will be mostly playing. While listening rooms will range from large to small and interior surfaces from absorbing to reflecting, our choice of music may similarly range from a preference towards natural instruments to electronically engineered sounds, from homely studio atmospheres to huge live venues.

    If our listening position is at relatively low range, a speaker’s ability to perform well at high volumes will be less significant than its capacity to provide time and phase alignment at a close distance. If our preferred music is mostly that of studio recorded natural instruments and voices, our speaker’s ability to recreate the precise studio atmosphere will be more appealing to us than its ability to highlight the types of base lines found in artificially designed effect sounds that are found in movies and electronic music. If we have the necessary space to experiment with the positioning of our speakers, we will probably find that nearly all types of loudspeakers offer enough bass extension to perform well, even without the aid of additional subwoofers being placed in the room.

    Horn-loaded speakers are among the oldest variety of speakers, dating back to a time when electronic amplification was not yet available. The amplifying effects of animal horns and conches were used for public address, even before music was recorded. Anyone who has heard announcements made over a public address horn will understand that horns cary some frequencies better than others, thereby changing the natural tonality of the addresser. Today, horn-loaded speakers are mostly used in settings where music needs to be cast at high volume and over long distance, such as live concerts. Similarly, if live concerts played at high volumes are our preference for home listening, horn-loaded speakers might be our our choice of medium.

    Today, the most common type of loudspeaker for home use is still of a relatively unexciting box shaped design with moving coil drivers that are made of paper or similar light weight materials. This design provides lots of freedom in terms of room placement and usually offers specialist drivers for each frequency range to assure for accurate reproduction of sound. Since the moving components of moving coil driver designs are relatively heavy, there is at least some unintended time lag involved when bringing them up to speed and slowing them down which leads to a smothering of frequencies. For those of us willing to experiment with more nimble designs, both planar magnetic and electrostatic speakers may present interesting alternatives in sound reproduction.


  • 21. Silencing open inputs

    21. Silencing open inputs

    6/4/2020

    Author: Karsten Hein

    Category: High Fidelity

    The first time I read about RCA caps was in the instruction manual of the Restek V1 preamplifier. In this it is explained that all unused RCA input circuits must be shortened to suppress noise potential coming from high frequency radiation. It is stated that the unit could not otherwise fulfil its specifications in terms of total harmonic distortion and signal to noise ratio. Not knowing what to make of this information, I was relieved to find that they come in packs of a dozen and are relatively inexpensive to purchase new.

    Despite the Restek V1’s gold plated inputs, I decided to purchase the caps from a Chinese importer called Audiocrast. The base material is brass which has then been rhodium coated. These plugs were much better rated than their golden equivalents, otherwise I would have attempted to lessen the effect of material transitions by using the same contact material as the inputs.

    On the Restek, the plugs have the effect of making the noise floor dead silent on all sources. This is less pronounced on the phono stage where the input signal is much lower than that coming from the DAC. Listening to Diana Krall’s ‘Turn up the Quiet’, the fading out of the studio’s ambient noise is much more apparent with the plugs than it was before. This means the system’s noise floor is far lower than that of the recording studio. I also can appreciate listening at higher volumes much more than I did before, simply because the music stands out more prominently from the background. I especially enjoy the effect the plugs have on stage depth, which has just become a little more realistic. Restek was not wrong in suggesting the use of the plugs. If your system is capable of great sound, this little add-on can well be considered an audio essential.