Neil Walker

This utility provides a series of tests for use with the Music 5000 synthesiser to help in setting up an amplifier and speakers.

Load and RUN 'U.Testing' from the Main menu. Function key f4 is now defined as RUN. Select the 'Stereo Test' option from the menu. Each of the choices displayed is explained below.

PHASE check

This is the most difficult test: a check that the left and right speakers are in phase. That is, that when fed with the same signal the two speaker cones move in and out together. If any work has been done on the speakers - leads extended, plugs refitted, baffles made from doors, etc. - it is possible that the speakers are out of phase.

The different sound of an out-of-phase system can be very subtle: the stereo image position will be rather vaguely defined and the bass response tends to be poor, and the AMPLE 'INVERT' word may not give the required effect when your program is used on another system.

It is easily cured by reversing the connections to one of your speakers - it does not matter which one.

This test depends on sound cancellation and works best if the speakers are placed close together (around 12" apart) facing each other. It is possible to perform the check without moving the speakers, but this needs experience of the sounds produced on your particular system.

To try the test, select the PHASE option. This toggles, each time it is selected, between in-phase and out-of-phase signals to the speakers. The out-of-phase sound should be of an obviously lower amplitude and lacking bass, than the in-phase sound. Listen to the fundamental where the difference will be quite large. The higher harmonics are affected less.

If you hear the loudest bass on the out-of-phase sound reverse the connections to one of the speakers, at the speaker end or in the speaker plug. But remember to turn the amplifier off first - you are safe, but transistor amplifiers object to accidental touching together of speaker leads, and may go faulty in an expensive way. Before switching on again check there are no stray strands of wire left to short circuit the speaker leads.

If you have four or more speakers in use, deal with them in pairs and then match the pairs together.

Stereo Check

Each time this option is selected it cycles through right speaker on, left speaker on, and both speakers on.

With right or left speakers on the sound should only come from one speaker; if sound comes from both this is nothing to do with the speakers. Look at the amplifier input leads: somewhere the two inputs are joined together.

VOICES off

Silence - very popular with other people in the same room.

PAN check

This test is useful for placing the speakers relative to where you are sitting. On each selection it pans either the right voice to the left or the left voice to the right.

Sweep both

This test checks the overall frequency response of your system. It also helps to locate mechanical rattles or buzzing noises.

Keep the volume down on this test. Both speakers are fed with a very low (maximum negative SHIFT) to a very high (maximum positive SHIFT) frequency. High volume levels may damage your amplifiers and speakers. The speakers will flap around at very low frequencies and your amplifier may object to high levels of high frequencies. The SHIFT number tells you what is happening.

You will not hear anything at the extremities of the frequency spectrum; the point at which you start to hear or feel low frequency sound is mainly determined by your room and speakers. If you are youngish the speakers will be probably be the limiting factor with the higher frequencies; otherwise, as with me, it will be your ears.

Sweep Right

As above but right speaker only.

Sweep Left

As above but left speaker only.

Step up

As 'SWEEP both' but it steps the tone up in octaves.

Step down

As above but steps tone down in octaves.

These two tests give a quick check of response. Again, go easy on the volume.

Stereo test