Turner

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  • Turner Audio
  • 1 Adams Place, Watson, Australian Capital Territory 2602, Australia
  • Official website
  • info@turneraudio.com.au
  • +61 6241 2760
  • No fax number available

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Equipment[add model]

Turner manufactures or has manufactured the following equipment (click to expand models list):

Dynamic Speakers
 

General information [contribute]

Turner Audio web site (July 2002):

What is the design philosophy for Turner Audio?

We must ask, why have a philosophy? We cannot be at every concert. What are we to do? Make sure all wonderful parts will act together, to allow the goodness of the recorded event, to reach us unblemished, to nurture our souls.

For preamps, all circuitry is 100 % class A operation, and since the dynamic range of tubes is so enormous, the operation at low output voltages assures negligible distortion production and sound you would die for. Triodes are predominantly used, in a variety of topologies, to suit the needs of the usage. Whilst some would say you cannot beat class A integrated circuit chip opamps, or discrete solid state preamps, I have yet to hear anything as emotionally engaging, and as warmly inviting as a well made tube preamp.

For Power amplifiers, you can't beat class A amplification. All Turner Audio amps use a large % of class A in their operation. This results in substantially linear distortion free ) amplifiers even without any applied negative feedback to correct distortion.or reduce noise.

Some negative feedback is OK. But we must reduce output impedance, to suit modern speaker needs, and that means that some inverse feedback needs to be applied. There is nothing subjectively negative about negative feedback. It is often called inverse feedback, and if well applied it has a positive outcome for the music.

Global negative feedback is OK, when the amp is substantially linear, and has broad bandwidth and minimal phase distortion before feedback is applied. And since well designed tube amps need only 12 to18 dB of negative global feedback, it is easy to maintain stability without running the risk of too much feedback

You don't need a huge amount of feedback. In Turner Audio tube amps, even without any applied feedback, the noise is reduced to negligible levels, and the only reason why negative feedback is applied is first to reduce harmonic distortion to less than about 0.2 % at 1 dB below clipping in most PP amps, and a little more in SE amps, and second to reduce output impedance to a low level of around 0.4 ohms or less. Triode amps need only about 12 dB of global feedback, and Ultra Linear need about 16 dB of feedback. There is no need to emulate the absurd efforts of many 1950 makers to win sales by achieving vanishingly small distortion igures by applying 30 dB of feedback. In some cases this much feedback is counter productive and can make the fidelity worse in terms of transient response.

Nearly all solid state amplifiers are class AB with a tiny amount of class A operation, and the three demons of crossover distortion, appalling power supply noise, and constant current output impedance characteristics require the use of vast amounts of negative feedback to correct these inherent defects. It is not unusual or a total of 80 dB of feedback to be used in SS amps. Whilst many argue in favour of SS, because they measure so well when the feedback correction circuit oops are in place, many would also say that tubes still sound superior. Generally the people who say each thing are not the same people.

Tubes are not bad. They have been with us now for nearly 100 years, since the first triode was made in 1903. They have been getting better for audio use ever ince. Computer control of the fabrication process is common nowdays.

You can't beat wide bandwidth. So the bandwidth before the application of negative feedback and stability networks is at least 15 Hz to 50 kHz. This means an absence of delay within the amp before or after negative feedback is connected, and complete stability is unconditional.

Tube amp distortion is benign in most class AB push pull amps, and even more forgivable in single ended amps. Any well made class AB Tube amp will display about 0.2 % of THD at just below clipping, near full power, with feedback. This amount is ghastly compared to the 0.001 % produced by some solid state amps, often at four times the power level of more. But when we look at the meaning of these figures, we can see that 0.001 % is a completely meaningless achievement, and usually done to generate sales. Tube amps do indeed have a high measured figure of harmonic distortion, but it declines in severity towards zero at zero output. The reduction towards zero is generally slightly better than a linear reduction. This means that a 50 watt amp at 2 watts will only produce 0.025%. Now 90 % of listening is done at 2 watts or less, which would be at 96 dB SPL or less. The harmonics at 2 watts are nearly all third harmonics, with a little second harmonic. When one calculates the sound levels produced in the speakers from tube amplifier distortion, at normal levels, it is so low that nobody can hear it.

There are no crossover distortions produced at low level operation of tube amps. The percentage of solid state crossover distortion is worst at low levels, 2 watts or less. These harmonics which are produced in many solid state amplifiers are far more destructive to the sound fidelity than typical tube amp distortion, even though they may measure at a pretty low level. This is because the harmonics produced are a potpourri of high numbered multiples of all fundamental frequencies present, along with the potpourri of intermodulation products. Testing amplifiers with single tones into resistive loads does not tell us the full story about how something may sound. How it will sound depends on test signals by Bach, and Bethoven, and possibly that flibertygibert, Motzart. Human hearing reacts with increasing displeasure as the number of unmusical electronically generated harmonics increases, so the true weighted significance of solid state crossover distortion is far worse than small amounts of low numbered harmonics produced by simple class A circuits, such as second or third. 0.025 % of 12th harmonic sounds as bad as 36 times 0.025% of second harmonic, i.e. 0.9 % Put another way, solid state amps need all the help they can muster from the use of negative feedback, unless they are set up in substantially class A, and so few are. Many listeners of fine music are aware that tube amp distortion is of no consequence because in the natural world, this type of distortion occurs, but not that of class B operation of solid state amps. Once levels over 5 watts are exceeded, loudspeaker distortion becomes the far greater component in the sound that is heard, if we have a decent amp. And we must accept that as levels at the recording studio rise, so will microphone distortions. Luckily, speakers and microphones do not produce crossover distortion, and work with their greatest clarity at a couple of watts.

Simple designs are used in Turner Audio amps Many weird and complex designs have evolved over the last 80 years of tube use in audio applications. None of these are used by Turner Audio. Just simple effective circuits of no more than three R-C coupled stages with excellent output transformers. It is a recipe that nobody can beat, and it has stood the test over time.

You can't beat quality components. The quality factor, ( or Q ), of a system is the sum of its parts. So there is no favours gained by using cheap and nasty parts, such as sub standard resistors, capacitors, tube sockets, tubes, wire, solder, switches, terminals, potentiometers, and so on. So when the goodness factor Q of all chosen parts is added together, the outcome will please anyone's ears.

The sound quality is determined mainly by the circuit topology, i.e. class A or class A-B and the way negative feedback is employed. There is often extreme and obsessive focus on component quality in high-end circles, without any understanding of how a circuit works. No amount of component quality, mainly of caps, resistors and cables will overcome poor applications of circuit theory.

Many of these plug ins and add-ons such as cables and power conditioners do absolutely nothing except make a listener feel good about what he has been able to achieve by purchasing something for his or her system. Whilst any expensive cable or tweak is not going to do any harm to a system, it is important to get the room, then the speakers, and then the amplifiers and source up to a high standard first, in that order before worrying about cables and other minor tweaks. Once a total listening environment and system is established, music can be reproduced with great satisfaction, and with some fondness and respect for the hardware, especially if the amps are tubed.

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