Have a question regarding your system set-up or just a general inquiry?

TECHNICAL QUESTIONS AND ANSWERS

How do I get the best out of my Plinius amplifier? What Loudspeakers should I select? How do I use the Ground Lift switch on my amplifier? What is Direct Coupling? How long does it take for my amplifier to 'warm up'? Is it necessary to leave all my audio equipment on? What type of speaker cables and interconnects should I use? How do I remove hum from my system?

We expect our customers to find our amplifiers highly satisfying and very musical. Every now and then we are surprised when someone is less than enthusiastic. This sometimes has happened when a reviewer has evaluated a PLINIUS product, and now and then we read of someone on an Internet forum who has tried a PLINIUS amplifier, and found it less than expected. We believe in each case this is due to some shortcoming in the user's system.

We have found that the most common reason for dissatisfaction is the mains power source. Specifically the series impedance (or resistance) of the mains circuit the amplifier is plugged into. In the USA this is more of a problem because of the lower voltage, and higher current demands. The ultimate solution can require a heavy dedicated mains circuit, just for the audio equipment, but it is important to consider a few simple factors first. We have found that any mains conditioner, or filter, that acts in series with the mains (and most work this way) will starve the amplifier and negatively affect the sound. Try plugging the amplifier directly into the wall socket.

In the USA try to keep all equipment on the same phase. If your wiring is at all suspect you could try a power conditioner such as the Richard Gray which operates in parallel rather than in series with the mains. We have had great success with these. Improvements can also be found if old mains circuit breakers and wall sockets are replaced with new, as you need the best quality contacts you can get. Also let your amplifiers break in before expecting the best sound. It can take up to a week before they begin to relax and sound their best. Once turned on, don't turn off, but rather leave the product in standby or mute when not being used. Taking account of these factors, we hope you will gain more satisfaction from your PLINIUS amplifiers.

Choice of loudspeakers is one of personal taste, providing the chosen loudspeakers are suitable for use with your amplifier. Be certain that your loudspeakers can handle most of the rated output of the power amplifier being used. As a general rule, the use of high power (200 watt RMS or greater) loudspeakers is recommended and desirable with our SA Series power amplifiers. However, our experience indicates that low to medium power loudspeakers (100 to 200 watt RMS) are also quite often suitable for use on all of our amplifiers (including integrated models) provided the volume is maintained at a level where no distortion is audible.

Impedance of the loudspeaker load is important to ensure the rated performance the amplifier used. Any combination of loudspeakers may be used but the total average impedance load for each channel should be within a range of 4 to 8 ohms.

This switch allows the signal ground to be disconnected from the chassis. In some installations a hum loop may exist due to duplicate ground paths from different equipment. Use this switch to remove the connection from 0V to ground thus allowing some flexibility in your particular set-up. One position may be quieter than the other. See the section on system noise below.

All of our power amplifiers (the SA Series) are configured as 'direct coupled'. This means that any DC fed to the input will be amplified and will appear at the output. As you can imagine, large amounts of DC are hazardous to loudspeakers and should be avoided. For this reason care must be taken in selecting a companion preamplifier. As Plinius preamplifiers are 'AC Coupled' they block any DC component from being present at the outputs, hence ensuring your loudspeakers are protected.

It should be noted that many preamplifiers (such as valve types) may have a DC component at their output. Please check the manufacturer's supplied documentation to ensure your system is going to offer enough protection from DC. Also, you should always turn your preamplifier on first to allow it to stabilise prior to switching on the power amplifier.

Electronic components must work in their 'linear' range when amplifying music. When switched on from cold the correct point in this linear operating range won't be reached until the temperature inside the equipment stabilises. Once this point has been reached the sound will be at its optimum. In addition we have found that leaving the equipment on for an extended period of time further improves the sound produced. As a guideline you should allow our amplifiers a day to settle and expect further subtle improvements for up to a week beyond this.

From a sound point of view it is definitely worthwhile leaving equipment on as discussed above. In addition, with properly designed solid state amplifiers, avoidance of on-off switching will actually enhance the product's life as the stress of the on-off cycle is avoided. Power usage at rest is negligible, typically being no more than a low powered lightbulb per piece of equipment. Of course the SA series Class A power amplifiers should be left in Class AB when not being listened to in order to minimise their power consumption. They may be switched into Class A about 15 minutes before any serious listening session with no sonic penalty.

There is no doubt there is a difference in sound quality and tonal clarity when comparing different cable brands. All we can suggest is that you buy within your budget and use your own ears to determine your preference. Your dealer should be prepared to help with cable selection, and may be able to offer a variety for you to listen to. You may hear differences that are hard to quantify, but don't look for right or wrong, it is simply a matter of personal preference.

Current practice is to keep loudspeaker cables as short as possible and interconnects long enough to make up the difference. Of course this is dependent on your individual requirements, and the quality of the cabling is more important than their individual lengths. Note that for interconnects exceeding a length of around 2 metres you may need to look for low capacitance types to avoid affecting the signal quality. Alternatively balanced interconnects may work better for you over longer lengths.

Most audio systems will contain some small residual hum or buzz, and very few systems are totally silent. As a rule of thumb hum or buzz heard right up close to the loudspeaker should be lower in level than any hiss present. Also it should not be audible at your listening position.

If your system has a hum or buzz that you find annoying, there are a few things you can check to find out whether the source of the noise is electrical or mechanical (or both).

ELECTRICAL NOISE: If the hum or noise that is the problem is heard at the loudspeakers when no music is playing then the source of the noise is electrical. In order to find this noise you need to work from the loudspeakers back. A loudspeaker can't generate noise on its own so the first item to check is the power amplifier. Turn off your system and disconnect the power amplifier input cables. Turn the power amplifier back on again and listen. If the hum or buzz is still present then it is originating in the power amplifier. If it has gone then it is originating somewhere else in the system. In this case turn your system off again, reconnect the power amplifier input cables, then disconnect all of the preamplifier's input cables (from CD, tuner, turntable, etc). Rotate the preamplifier's volume control to minimum. Turn both preamp and power amplifier back on again and listen. If the noise is present now it is originating from the preamplifier, or from the connection between the preamplifier and power amplifier. Try the ground lift switch on the power amplifier, this may resolve the problem. If you have a Plinius preamplifier then try the ground lift switch on that as well. If you cannot resolve the problem at this point it is possible that you have a faulty preamplifier, faulty interconnect(s) or possibly pickup of an external interference such as an RF signal. You may need specialised help to diagnose this. If the system is quiet then you should proceed to connect each source item (CD, tuner, turntable etc) in turn, using the preamplifier, or power amplifier's mute switch each time, and listening for the return of the noise. When it returns you will have identified it's source and be able to attend to the problem. If one of your source components (CD, tuner etc) is the cause of a system noise it could be due to a ground loop. This occurs when more than one item in a system has its signal ground connected to the power ground. Circulating currents in this loop can give rise to a hum or buzz. In this case try a 'cheater' plug (no ground connection) on the power connection of the offending item. You should also try the ground lift switches.

Of course good ground connections are basic to any low noise system. You should as a matter of course ensure that your power and preamplifiers are both plugged into the same wall socket. It is important that your CD player, tuner and processor are connected to this same socket as well, even if through a multi-distribution box of some sort. Note that double wall sockets are almost always paralleled together, so using the two plugs on the same wall socket equates to the same ground.

Video recorders, DVD players, surround processors, and any device that is connected to a television cable or satellite dish can cause a loud buzz. If by the process of elimination above, you determine a component like a VCR is causing the hum or buzz to occur, and checking the earthing doesn't remove the noise, you may require an isolation transformer to physically separate the VCR power supply from the mains. You may also find that a balun fitted to your antenna wire could help.

If after all this the noise is still present and annoying, it's time to enlist specialised help. You should ask your dealer for assistance.

MECHANICAL NOISE: Some items of equipment can directly radiate a mechanical hum or buzz. This mechanical noise almost always originates from the device's power transformer. Place your ear close to each component of your system and listen. If you hear a hum or buzz coming from within your equipment, then the noise is mechanical. 'Lamination rattle' occurs in all transformers to some degree, related to the quality of the transformer and the quality of the line voltage. If the noise intensity varies depending on the time of day, sometimes even the time of month, then it is due to the quality of the AC supply voltage in your area. In this case you're at the mercy of your energy provider.