30 years dedicated to making audiophile amplifiers Copyright © avondale audio
chesterfield, england, uk
telephone +44 (0)1246 200096
breathe LIFE into your music
Our customers think so.
"who would have believed that merely changing one transformer for another, would create so much improvement in the sound of my Naim 180, my grateful thanks" CT Hull
There are many audio transformers derived from common or garden industrial units having little or nothing to do with our beloved hobby of high fidelity audio.
Some toroids exhibit such high levels of mechanical noise, it becomes not only audible in the listening environment but the harmonic content of the energy field is interposed onto the musical signal, the regulator systems being incapable of dealing with heavy harmonic saturation.
We supply Audiophile Grade toroidal transformers from Advanced Sound Technology (AST), ranging from 120VA through 2KVA.
Advanced core material and winding techniques ensure the highest flux density for maximum transients. Probably the lowest impedance secondaries ever made for that extra control in the bass.
Special techniques ensure that HF and RF transmission is minimised meaning a cleaner presentation. Encapsulation in a special epoxy resin guarantees a total absence of noise and vibration (no more audible grunting and a background silence that has to be experienced to be fully appreciated).
With a substantial increase in the mains borne artifacts now coming into our homes via the distribution network, it is becoming more important as the months go by to eliminate possible side effects before they happen.
Modern production techniques ensure that toroidal transformers are wound to strict standards particularly if they're specified for high end equipment. Even so, problems can and do occur where the incoming sinusoidal waveform contains a great many unwanted and undesirable effects.
Mass produced commercial grade toroidals are worse than useless for our needs unless the incoming waveform is the purest sine wave - something rarely found in this day and age. Once applied to the toroidal transformer, these various artefacts create havoc with the amplifier supply components - something even the most sophisticated designs and techniques are powerless to stop. Results are sometimes catastrophic and the sound becomes polluted to the point where the expensive system sounds no better that a low quality supermarket offering.
Some very large and expensive solutions in the form of regenerator systems are currently being marketed as the answer to all our problems. The mains is rectified then smoothed by a bank of capacitors along the lines of a main amplifier supply section. A generator running at a notional mains frequency is then used to synthesise a sinusoidal waveform, which is then passed into a power amplifier section, reconstituting the mains supply to drive the connected systems. Drawbacks with this process are that the impedance of the outgoing supply is higher than that provided by the National Grid and of course, the equipment is large, heavy and expensive - not only to buy but to maintain in service.
Another possible cure is to employ a mains isolating transformer with a secondary winding of such capacity as to emulate the parameter of the National Grid. It has been postulated that for even a medium power amplifier system of 100 Watts per channel, a 3KVA (Three Kilowatts), transformer is the basic minimum required to maintain transient integrity.
Whilst transformers rated at 3KVA and over are widely available, the quality of these should be unimpeachable, otherwise we are left with most of the problems we began with albeit manifesting themselves in a slightly different format. The humble factory produced commercial toroidal will do little else than to provide a facsimile of the waveform entering the device by the primary winding - this along with some internally generated spurious grunge of its own. The only redeeming feature of this strategy is that the outgoing supply from any transformer is inherently balanced - a desirable aspect in the opinion of many audio engineers.
Going back to square one for a moment, it is helpful to determine just what we expect of a transformer used to provide a stable AC power reduction for use in high end audio equipment. Below, there are listed a number of desirable, if not essential qualities, needed for the accurate transformation of the incoming mains supply:
Noise - Within the domestic environment, external mechanical noise overpowering the lowest musical notes is undesirable in the extreme. A 'buzzing' or 'grunting' transformer not only causes severe annoyance in the listening environment but is able to introduce such severe harmonics onto the supply lines of an amplifier that any thoughts of High Fidelity reproduction of music have to be abandoned.
Some commercially produced transformers sold under an 'audiophile' banner are little more than useless for our purposes. It should be recorded that the Holden and Fisher toroidals once produced for Naim are sadly no more but are still regarded as some of the best performing toroidals ever made for audio use - a shining example of great design and execution.
Temperature Rise - some commercial toroidals produce much heat even when lightly loaded. This is usually a result of cost cutting during the costing stage where the core is derated to suit the application. The result is a hotter assembly in order to extract the very last drop from the design but which can have deleterious effects on adjacent components such as electrolytic capacitors. As the temperature rises, so does the impedance of the transformer windings leading to another undesirable drop in expected performance.
Regulation - The perfect toroidal transformer should have a stable output under all specified load conditions in order to maintain the integrity of any transient delivery required by the musical programme. Failure to maintain such a standard will result in, at best, a collapse of the soundstage and at worst, some damage to the amplifier circuits caused by instability.
Low External Field - Although exhibiting the lowest external field levels of any transformer, the toroidal is still, if incorrectly designed and manufactured, capable of interfering with adjacent circuits particularly if the windings become crossed during the process. Noise injection into the power rails then becomes a foregone conclusion, which the finest, low impedance capacitors in the world are powerless to prevent.
Possible Solutions - During many years of working in collaboration with some very talented transformer designers, we at Avondale have come up with some clever, if not unique, solutions to our problems.
In considering core design, economies took a back seat when several new materials and configurations of these materials, become available.
Using the thinnest grain orientated steel strip practical for a transformer, we were able construct a core with the capability of absorbing virtually all the National Grid is able to throw at it without becoming saturated. Using some very advanced winding techniques and specially produced wire enabled the designers to eliminate virtually all of the problems encountered by the toroidal manufacturer.
The result is performance unequalled anywhere in the world of audiophile quality transformers. Simply replacing a standard common-or-garden toroidal transformer, nothing more, in any manufactured amplification item, will result in an immediate hike in perceived performance.
Forming what is effectively the lion's heart of all Avondale Audio amplifiers for many years, the supreme AST transformers are now to be made more widely available to the audio enthusiast in the form of a new and even better range covering most requirements and power needs.
Ranging from a deceptively powerful 100VA in various voltages from 2 X 15 up to 2 X 30V, the range keeps on going past 2KVA with secondary voltages available off-the-shelf up to 50-0-50 and others to special order.
Twin primary windings ensure their suitability across the world.
Prices will be announced shortly.
Do you need technical help with transformers? You only have to ask.
If you have not previously spoken with us, then please do call or email us so that we can advise on the right transformer for your application.
Don't forget, we stock Cases, Capacitors, Cables, Connectors, Switches, Screws, Semiconductors and just about everything you will ever need to make your very own high end amplifier system.
If you cannot find what you're looking for on the site and need some help, please write to us. Or just call us on +44 (0) 1246 200096 during UK office hours.
30 years dedicated to making audiophile amplifiers Copyright © avondale audio