Carbon‑fibre cables, gold‑plated connectors, contact enhancers and spiked, lead‑filled supports — not a list of props from a science‑fiction blockbuster, but a selection of the many accessories available from hi‑fi specialist dealers. Martin Walker enters the twilight zone to sort fact from fiction and discover whether any of this black magic can help in your studio.
It's easy to be derisive when you see, glancing through hi‑fi magazines, that some people are prepared to spend hundreds or even thousands of pounds on a couple of metres of cable, or bypass their compact disc player with so many external 'add‑on' enhancing boxes that there's only a minimal amount of the original player in‑circuit. However, there are scraps of magic to be found amongst the hi‑fi myths, and considering how many more cables and interconnections there are in a typical recording studio, if these tweaks do work, the benefits to the studio environment could be considerable.
At first sight, hi‑tech musicians and hi‑fi enthusiasts would seem to be poles apart in attitude. However, despite the incredible leaps in technology each year, some of the high‑end hi‑fi amplifiers are beginning to emerge in new 'retro' guise, complete with valves, since the cognoscenti maintain that some amplifiers designed originally in the '50s still sound as good, if not better, than many made today. But hang on a minute... Valve amps sounding better than solid state? Surely this will ring a bell with many musicians. Guitarists have known for decades that where warmth and 'musical' sounds are required, valve amps have always sounded better. And again, guitarists as a breed are quite happy to remove the factory‑supplied pickups to fit specially wound ones in their place — surely these are 'add‑on enhancements'? Recording musicians, even those who are firmly attached to solid‑state technology, are happy to enter the world of psycho‑acoustics and use enhancers. It is not unusual to find an ADAT preceded by an 8‑input valve interface to add that certain something to an otherwise digital chain.
So perhaps there's not that much difference between the two camps after all — certainly not at the upper levels, where pro and semi‑pro gear often comes from manufacturers who have a foot in both the hi‑fi enthusiast's and the hi‑tech musician's worlds.
Shakin' All Over
One item that is de rigeur for any hi‑fi enthusiast, but that rarely appears in the average recording studio, is the humble speaker stand. Although SOS has carried many reminders, over the years, of the benefits of supporting speakers properly and not sitting them on the mixer meter bridge, many people still take the easy way out and compromise the sound of their monitors. A loudspeaker cabinet can only give of its best when rigidly mounted. In larger recording studios, purpose‑designed monitors are 'soffit' mounted directly into the front wall of the control room (giving them an extremely firm mounting), but any speaker simply placed on a meter bridge or perched on top of a rickety stand will itself be moving in time with the music. The signal in the loudspeakers ideally moves the cone like a piston, but unless the cabinet has infinite mass it is bound to move slightly as well. This equal and opposite reaction, particularly with the higher energies at the bass end, will cause a 'muddying' of the sound — in effect, a mechanically induced distortion of the music signal. Many hi‑fi speaker stands are also designed to be filled with dry sand (or even lead shot!); as well as damping any resonance in the stand, the greater mass will provide further stability and rigidity.
In addition, stands are often supplied complete with 'spikes', which are designed to invisibly pierce a carpet so that the stand is better coupled to the more solid floor beneath. This ensures a level and stable base, but the use of spikes is controversial. Since sound travels faster in solids, it is possible that some sound will reach you via the stands before the airborne part arrives, particularly if you have floating wooden floors. Some people prefer to spike the stands to the floor to make them rock solid, and then put neoprene or lumps of Blu Tak between the speaker and stand to add a little 'give' — not enough to compromise rigidity, but sufficient to prevent too much coupling of cabinet‑borne vibration to the stand beneath. Others prefer to spike the speakers to the stands, and then decouple the stands slightly from the floor by using rubber feet. There are no hard and fast rules.
Without contact cleaners, your jack fields may still resemble an avenue of tree trunks lying across planks!
Although stands can tighten up the bass end of the signal, giving a tighter and less 'flabby' sound, they will also have significant effects in the mid‑ and high‑frequency ranges, giving a more focused and detailed sound across the whole frequency spectrum. This is not mumbo‑jumbo. If there are high levels of bass signals, the high frequencies will be emerging from slightly different positions as the cabinet vibrates. At 10kHz, the distance in air between minima and maxima of the waveform is about 8mm, and if the whole loudspeaker cabinet is vibrating, you can hardly expect high frequencies like these to remain focused.
A second issue is that by using a stand that places the loudspeaker significantly above the level of the mixing desk, the effect of reflections from the top surface of the desk will be smaller. Typically, with the speakers perched on the meter bridge, the distances involved will result in a compromised mid‑range performance, due to reflections interfering with the direct sound. You can quickly test this out with your own setup by placing acoustic tiles or a few duvets over the mixer to absorb these reflections. You will need about four inches of thickness to affect frequencies down to about 200Hz — and if you hear an improvement, it's time to move the speakers! If you mount the speakers in 'free space', you will also get a cleaner sound.
In the past, finding stands high enough for use in studios has been tricky, but some manufacturers are now producing stands up to 1 metre high. Atacama is one company with an enviable reputation in hi‑fi circles. Their SE1000S stands fit the bill nicely, but they also provide a bespoke service for recording studios, making any size of stand to order, at a slightly higher cost. Target Audio also have a 1‑metre stand (the MX100) in their range, but this will only suit smaller and lighter monitors.
At the other end of the audio chain, vibrations can affect CD, DAT, DCC or ADAT players, amplifiers, or indeed any other electronic equipment, either indirectly, by aggravating the microphonic effects of certain electronic components, or directly, where moving parts are involved. Although vibrations may only be present at extremely low levels, they may still be sufficient to slightly colour the sound. Capacitors are one of several electronic components that can be affected, producing a voltage in response to mechanical vibrations. Again, you may think this sounds bizarre, but try turning up your amplifier and tapping the cases of other equipment — my Boss SE70 effects unit certainly produced audible sounds from the speakers!
The solution is to further decouple the equipment from the source of vibration, by using absorbent feet made out of a material such as Sorbothane or neoprene, or even lumps of Blu Tak. One company that has been mentioned before in the pages of SOS is Spectra Dynamics (in the Widgets section of the October '95 issue). Their range of Deflex panels and Foculpod feet is made from a specially formulated low‑resilience polymer that has "exceptional shock absorbing properties", and works well when you need to isolate sensitive equipment from vibration. The most likely candidates for isolation include DAT and CD players. Again, you may be surprised at how much vibration you can feel on the casing of your equipment when playing music at typical levels in the studio.
Moving from mechanical to electrical problems, one of the prime candidates for improvement is dirty or intermittent contacts. Hum levels due to earth loops may vary, especially if plugs are removed and re‑inserted, because this wiping action tends to clean the contact, effectively establishing a new hierarchy for loop paths. Radio interference can also be a problem, since leads will tend to act as aerials, either reproducing faint radio stations in the background at low levels, or be prone to periodic breakthrough from passing taxis and police cars. Dirty contacts can also cause a loss of low‑level detail, by adding a small amount of noise due to varying contact resistance. Two products widely used by the hi‑fi brigade are contact cleaners and enhancing fluids. As with various other hi‑fi tweaks, these are definitely not the 'snake oil' that you might suppose. In fact, a casual look at typical advertising blurb shows that these fluids are widely used by the likes of Ampex, Dolby Labs, and Switchcraft.
Contact cleaners work by dissolving the oxides and sulphides that form as surface corrosion (this occurs with most metals to a greater or lesser extent), leaving a much cleaner surface. However, if you look at the average jack plug/socket contact under a microscope, it would resemble nothing more than a tree trunk lying on a plank — touching in various places, but certainly not the smooth contact that many people would suppose. Between the actual points of contact exist small air gaps. After the surface contaminants have been dissolved, an application of enhancing fluid leaves a thin film that fills many of these voids, providing a much larger total contact area and giving significantly lower contact resistance. A single wiping application will not only clean your contacts, but keep them in tip‑top condition for months, or even years, by preventing further oxidation. The thin film also tends to migrate to the other side of the contact, so that, for instance, cleaning your plugs will ensure that some of the film will end up on the socket as well. Although these solutions can be expensive when bought in concentrated bottle form, unless you need to use them regularly, you can now also buy them as packs of impregnated 'wipes'. A single wipe will provide enough fluid to clean a few dozen plugs.
I've discovered the benefits of contact cleanliness the hard way, and have maintained for some time a regime of cleaning my plugs every few months, using wire wool or Brasso on mains plugs and isopropyl alcohol on all the rest. Alcohol will remove surface dirt, but won't deal with oxides or sulphide layers. Having now tried DeoxIT and ProGold (from Caig Laboratories, and available from Russ Andrews — see contacts box), I am never going to be caught without them again. The difference is not just lack of RF interference, but greater low‑level detail with all signals. This is simply because the contact resistance is so much lower and more predictable. Cleaning and enhancing works particularly well in the case of speaker and mains contacts, where contact resistance is more significant, but will improve any contact in the long term. It's well worth giving this a try — without contact enhancers, your jack fields may still resemble an avenue of tree trunks lying across planks!
No other subject produces more stifled titters in the musical world than that of exotic hi‑fi cables. To the outsider, the idea of paying tens, hundreds, or even thousands of pounds for a metre or two of cable seems totally bizarre. Line‑level cables made from exotic materials such as carbon fibre, plated with silver or rhodium, or even made in solid silver, sell by the bucketload for hi‑fi purposes. Unfortunately, most come only in the phono‑to‑phono variety, so the only way to audition them is to buy a length of bare cable (if available) and wire it up yourself. One of the most common materials quoted is Oxygen Free Copper (OFC), and even the level‑headed Studiospares (and the SOS mail order pages) feature this. In fact, all copper cable contains impurities, but OFC normally refers to particularly low levels (typically 40 parts per million, rather than 234ppm for normal copper). Using this type of cable is said to reduce non‑linearity when passing signals.
In the real world, as long as output impedances are low and input impedances are higher by a factor of a hundred or more, the theoretical effects of different line‑level cables are debatable. Even using materials such as carbon‑fibre conductors, which result in resistance values a hundred times that of copper, excellent audio results can be obtained. For studio use, often a more important parameter is that of shielding. A cable that protects the audio signal from hum and noise, often caused by wall‑wart power supplies, computer monitors or dimmer lighting, is arguably more important.
One of the trickiest subjects to discuss is that of speaker cables. For years, nearly everybody assumed that as long as a 'thick' low‑resistance cable was used to minimise power losses, the composition of the cable was unimportant. Indeed, many of the first so‑called hi‑fi speaker cables were really just thicker versions of the bell flex that normally came bundled with the average hi‑fi system. Using a thicker cable not only made the speakers sound marginally louder for the same amount of power, but they were also better controlled, since, effectively, the output of the amplifier was more firmly attached to them in an electrical sense.
Many hi‑fi tweaks are like herbal remedies — people try them out and they work, and it's not until some years later that scientists finally come up with a rational explanation.
However, the connection between an amplifier and speaker is a complex thing, composed of resistance, capacitance and inductance, not only of the cable, but also of both the amplifier and speaker, and tiny variations in one or all of these three can have an audible effect. The main thing to point out is that different cables do sound different, especially when they're passing complex musical signals. With a standard 8Ω speaker, a dynamic variation in the speaker cable of eight millionths of an ohm would generate a signal 60dB down on the original signal.
The huge problem is that, due to the complex interaction between the amplifier, the cable and the speaker itself, what sounds good in one person's system won't necessarily work in another. Active speakers, which incorporate the amplifier into the speaker cabinet to remove the need for a separate speaker cable, bypass many of these sorts of problems. Certainly, if you have any choice, always shorten the loudspeaker cable, even if this means extending the line‑level cable to the amplifier. By all means try out a few samples of hi‑fi cables (most reputable hi‑fi dealers will let you borrow a few for a day or two to audition them), but don't get sucked into the black hole of finding the 'best' cable. Such a thing is the Holy Grail of hi‑fi design; the perfect cable does not exist.
There's as much money spent on external digital‑to‑analogue (D‑A) converters for CD players as anything else in the hi‑fi world. These do have a direct application for musicians, since they can be used for any digital signal, such as those from CD, DAT and so on. A few years ago, many 'consumer' DAT recorders contained somewhat indifferent converters, but today's models have been much improved.
As even humble PC soundcards begin to sprout digital I/O sockets, using external converters makes far more sense — if you can keep the signal in digital form within the PC, and only convert to analogue in the relatively clean electrical environment outside the PC casing, far fewer opportunities exist for interference and degradation. One DAC that has been mentioned in these pages before (see the Digital DIY feature in the July 1996 issue of SOS) is the DACMagic, from Cambridge Audio, which is now available in an improved Mk2 version. It's competitively priced, gained excellent reviews, and has the added advantage of providing three selectable inputs (two co‑axial and one optical), switchable from the front panel, and both balanced XLR and unbalanced phono analogue outputs, plus a digital output. Unlike most other models, it also accepts all sample rates from 32 to 48kHz, rather than just the 44.1kHz used by CD players. Prices of mass‑produced hi‑fi converters tend to be more competitive than specialist rackmounting devices, so if you have an application where you need to listen to several digital signals, this may be just the job.
Some of the so‑called 'improvements' are merely changes, and, as many people find to their cost, highly system‑dependent. Some tweaks do not stand up to rigorous A‑B‑X testing, where they are swapped in and out of circuit to audition the differences or improvements. When you want to hear an improvement, your ears can often deceive you, and it is perfectly possible for you to imagine you're hearing a better sound when played exactly the same thing twice in succession.
If you want to actually measure the changes brought about, the main problem is that, whilst audible, these tweaks often affect the signal in subtle ways that are difficult to quantify. As we have seen with dithering systems in digital audio (and which, incidentally, do make a mathematical and defensible improvement), changes in an audio system can be heard even when lower than 100dB down on the peak signal level. Although this sort of signal level is still measurable, the problem arises when trying to measure subtle ambient detail — the sort of audio changes that occur when we musicians employ enhancers and the like. There may well be an audible improvement, but coming up with a way of actually measuring it is more difficult.
Many hi‑fi tweaks are like herbal remedies — people try them out and they work, but it's not until some time later that scientists finally come up with a rational explanation. As long as you're not spending silly amounts of money, it is certainly worth keeping an open mind about such things, and using your ears as the final judge.
Most mechanical and electrical devices will benefit from 'running in'. Speakers, in particular, will sound harsher when first taken out of the box. This is because the moving parts have a certain initial stiffness that eases up after a few hours of use. For this reason, you shouldn't judge your new speakers until they have 'eased up', and this is why the demonstration models in the dealer's showroom will normally sound much better, as they have been well run in already. Many speaker manufacturers recommend running speakers continuously for up to 24 hours before active listening takes place.
Electronic equipment also benefits from this process. Some components change slightly in performance after being used for a few hours, and manufacturers will obviously design them to sound best over the long term. This applies to amplifiers, CD players, and, indeed, most other audio equipment — most will have a more 'relaxed' sound after being used for a few hours. However, large capacitors used for decoupling and smoothing can eventually become less effective after a number of years. If you have any equipment over 10 years old, and suspect that hum levels are not as low as they used to be, this may be the cause of the problem.
Finally, it is also a good idea to let all electronic equipment 'warm up' for at least 10 minutes before listening to it. It normally takes this length of time for the circuitry to reach a steady‑state temperature (known as thermal equilibrium) and, again, this often results in a better sound, as all components will have stabilised as far as voltage, current and temperature are concerned. Amplifier temperatures will rise further when actually playing music, but this should have far less effect on the sound than during the initial warm‑up.
In ancient times, alchemists sought to discover the secret of turning base metals into gold. Nowadays, even humble jack plugs from Tandy can be bought with the base metal already plated in gold. The reason for this apparent extravagance is not to lower the contact resistance, but to make it more consistent. Gold doesn't corrode, so contacts plated with it won't degrade as they get older and less shiny, as most other commonly used materials do. This would largely seem to render contact cleaners (mentioned elsewhere in this article) redundant. However, due to gold's soft and porous nature, and the fact that it is difficult to bond it well to base metals, an oxide layer can often form between the two, producing tiny 'blisters' that compromise the contact area. Also, to keep costs down, the gold is often extremely thin, soon wearing through to expose the base metal. In general, gold‑plated plugs and sockets are an improvement, but they will still benefit from enhancers like ProGold. Even if there are problems between the base metal and the top gold layer, ProGold is designed to penetrate the plated surface to molecularly bond to the base metal and seal and protect it. In the long term, it will not 'gum‑up' either — some cheap spray contact cleaners leave an oily film that attracts dust, which is not exactly what the doctor ordered.
The Path To Nirvana
If you want to try some of these tweaks out, the easiest way to start is by cleaning the pins of your equipment's mains plugs (particularly those of your CD player, mixer and monitor amplifier) with some wire wool or Brasso. If you get positive results, do the job properly with all your studio connections (mains, line and speaker cables) using DeoxIT and ProGold (or alternative products such as Tweek). Use DeoxIT first for maximum cleanliness, then wipe off and apply ProGold to enhance the clean contacts. Your patchbay will probably be the worst offender, and you may be surprised at the amount of extra sonic detail that emerges.
Along the way, discard all cheap audio cables with moulded plugs, and replace them with good‑quality plugs and cable (oxygen‑free, if you like). As even PC soundcard manufacturers start to put gold‑plated sockets on board, it is easy to lose sight of the fact that unless they maintain a positive contact, even a solid gold plug and socket will be compromised. In the case of the humble phono, widely used for soundcards, consumer DAT players and hi‑fi equipment, the best plugs are those with a split central pin that can grip the socket, and an outer collar that either has a twist‑locking action, or a set of slots that expand slightly when you push the plug home.
When making up cables, make sure that the connections between plugs and cable are mechanically sound before solder gets anywhere near them (solder should ideally not be used like glue, but instead only to support an already sound metal‑to‑metal contact). Finally, buy a pair of speaker stands of the appropriate height, and experiment with spikes, Blu Tak and rubber feet.
Contacts & Prices
Most manufacturers will be happy to supply catalogues of their full range of products.
DACMagic 2Mk2 £149.95 (typical street price).
DeoxIT and ProGold trial kit of wipes, part no. 37‑120 £3.95.
Atacama range of speaker stands; SE1000S 1‑metre stands £80.
Deflex panels and vibration absorbing feet.
Speaker and equipment stands; MX100 1‑metre stands £61.