So what makes the perfect amplifier?

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So what makes the perfect amplifier

Your ears, really!

Many years back we were told that a radar is designed around the magnetron. Of course this is true because microwave energy falls within a specific band or bands. I feel the same about loudspeakers and amplifiers.

What makes the perfect amplifier — Behringer NU4-6000 and Pioneer A-5

Enclosures are designed around the drivers used and power amplifiers around the power supply. Pre-amplifiers or voltage amplifiers around the program source.

Topology is also important, class A, AB or D? There are many topologies of course and a lot of design work goes into supply rail shifting techniques.

What about solid state or tube/valves? Mosfet or bipolar?

It’s rather an ambitious task to be the manufacturer of the world’s perfect amplifier because truth be told, although we are at critical mass we still have ways to go and yes, they’re damned expensive.

Boulder, Macintosh, Conrad-Johnson, Emotiva, Dynaco ST-70, take your pick. What is relevant though as your tastes go up, so does the price. Speaker prices easily go upwards of a million Rand and buying a top end amplifier you don’t sit with pine wood boxes.

How many times have you sat in an acoustically treated room and hearing a tiring lifeless display of sound from a 20 000 Rand system. Often not set up properly, often the acoustics dampen the high end flattering the low end. Always best at home and set up to hear what you want to hear and not the sales pitch.

This is a question posed by novices and experts and truth be told to dive into the mysteries of sonic performance of an amplifier one would need to analyse the input vs output signal through pretty sophisticated audio test equipment.

In many ways NAD is voted king of the entry to mid level manufacturer amplifier but I find with incorrect speakers they sound, almost, and dare I repeat, lifeless. I love Sansui, Pioneer and Kenwood which I would put in the same price range. Yet NAD is often rated the better, the 3020 is often even mentioned in the top 20 listings by many audiophiles yet the figures are not exceptional by today’s standards.

An amplifier which has near zero imperfection under electronic testing should yield very good sonic performance and often this is the case. The program material through the standard onboard audio DAC on your computer or notebook may not be high performance and will not do your power amplifier justice. There is a vast difference, say, in using a Xonar U7 which is what I use over the onboard, which in this case is a Realtek High Definition device. I have used the Focusrite Scarlett 18i20 which to my ears is better than the Asus and this can make a dull amplifier come to life.

Pioneer A5 modifications for line drive — Behringer NU4-6000 and Pioneer A-5 rear – note the modified 10K:1K XLR outputs to drive the class-D amplifier (also note the fan outlets, rusting – possibly too close to the Durban air).

Sticking to analog rules then we need to ensure that with turntable use there is no hum and noise. Going the high gain path of any pre-amplifier is where we start picking up issues, more often than not, man made. Entry level turntables should be avoided – often they are the mass marketed USB variety. So we then move on to reel tape recorders, supposed with exceptional quality heads and a great frequency range. The tape recorder head reproduction is also amplified with a great deal of gain, a good starting point for noise if the wiring is not of professional standard i.e. shielded, earthed properly etc. A good quality tape recorder’s reproduction can be frighteningly close to the real thing so possibly this is the best audio source.

What I have found and this is obviously opinion based, the amplifiers which have created the most impression are all rated at over 100W (continuous) per channel class AB which means big power supplies – they will always be heavy. There will be a lot of aluminium and copper for cooling and the transistors paralleled to handle 4 Ohm or even 2 Ohm loads for a continuous rating. Power amplifiers do not need to have millions of buttons – in fact it can cheapen the look. Class A amplifiers of 50W or more you would need a bulldozer to bring to your front door.

I have an NU4-6000 which is used to drive Eltax Millennium 500 series speakers (R2 000.00 2nd hand). These speakers are not highly rated by the audio community but the noise makers praise them endlessly. The Behringer amplifier is actually an exceptional match for these loudspeakers, easily driven to about 300W continuous, nice balance between highs and bass, which for rockers is real kick arse stuff. These speakers are made to be driven hard. On a 50W Sony amplifier I found my setup efforts rather a mishmash where Castle Knight 1s and 2s excel.

So looking at the amplifier, place first emphasis on the loudspeakers and program source. The general rule of thumb is to buy the most expensive loudspeaker you can afford. The amplifier is going to be your choice – always purchase a known brand and do research.

In conclusion: Many home enthusiasts are purchasing professional series amplifiers which are often more affordable than that designed for the so called consumer market. The preamplifier can be your choice or do what I have done, used an old Pioneer amplifier modified for line out (R500.00 Cash Converters).

By the way, here’s an exceptional article on the Behringer Class D NU6000 3kW x 2 and the KAM KXD7200 3.6kW x 2

Class D amplifiers are scorned or loved but one thing is for sure, they are getting better and of course, cheaper as well. I find they make excellent bass drivers.

To get a really good system going one should read up about crossovers, bi- and tri- amped systems. More about this later.