Ashdown MK500 User Manual download pdf (Page 3)

Operating Instructions

INTRODUCTION

The MK500 bass amplifier uses a brand new Ashdown pre-amp featuring a 12 band graphic equaliser for

the most versatile tone shaping available and Harmonic Emphasis to provide the ultimate in HiFi for Bass.

Coupled with balanced XLR instrument input and a simplistic design approach, the signal path is kept to

an absolute minimum for maximum signal integrity and pure tone.

FRONT PANEL FACILITIES

INSTRUMENT INPUT

There are two Instrument Inputs.The first of these is a Jack socket suitable for all Passive or Active bass

instruments with a conventional jack output.This will perfectly match the high impedance output from a

passive bass but also has sufficient headroom to accept the lower impedance and higher signal level from

active instruments.The second input is a balanced XLR input for the ultimate in low impedance

interconnection between bass instrument and amplifier.This may be used with both balanced or unbalanced

connections but is best used with a true balanced connection where it will give up to 100dB of common

mode rejection, cancelling any noise picked up on the instrument connection cable.

INPUT CONTROL

The INPUT control sets the signal level through the preamp in conjunction with the INPUT LEVEL VU

Meter.This is adjusted to give a reading of 0VU on the meter for average playing dynamics with occasional

peaks into the red region. Please note that the setting of this may have to be re-adjusted after modification

of the EQ controls. It is most important to set this control to the optimum (as described above) to get the

best noise free performance.

HARMONIC EMPHASIS

HARMONIC EMPHASIS is a new addition within this amplifier and consists of a circuit that takes the bass

signal and emphasises harmonics within it to produce a bright zingy top end. It is not an EQ circuit, it

actually synthesises new harmonics, adding these to the original sound.The best way to describe this is that

it is similar to the top end zing you get from a new set of strings.

This has a LEVEL control and can be switched in or out with the front panel switch.

Used in moderation, you will find it adds a lot of bright, high harmonics to the sound giving definition and

clarity not achievable in any other way.

GRAPHIC EQUALISER

The GRAPHIC EQUALISER section operates by boosting or cutting the level of signal at various frequency

points throughout the frequency range.With the sliders set on 0dB (in their centre ‘click’ position ) no

alteration is made to the signal. Moving any one of the sliders up will increase or ‘boost’ the signal at the

frequency marked below the slider. Moving the slider down will decrease or ‘cut’ the signal at that frequency.

The GRAPHIC EQUALISATION can be switched in or out with the front panel switch.

A carefully designed GRAPHIC EQUALISER is a very flexible way of varying the sound of a bass guitar and

if properly used will provide an extremely powerful method of tone shaping for your instrument.

Because of the flexibility and massive BOOST and CUT potential of this particular GRAPHIC it is

important to know how to get the best from it.

Firstly a few things not to do and the reasons why:

1. Do not boost or cut all frequency bands as this will have the same effect as increasing or decreasing the

overall volume level without affecting the tonal characteristic of the sound.

2. Do not use excessive bottom (30 to 40Hz) boost on the graphic unless your speakers can handle it.

Very few speaker systems are capable of handling frequencies as low as 30 and 40Hz with any degree of

efficiency. N.B. Boosting at 30Hz for instance will not add to the perceived amount of bottom end in

the sound, it will only make your speakers flap to no useful effect. In fact boosting at 100Hz or 180Hz

will have the apparent effect of adding far more bottom end than boosting at 30, 40 or even 60Hz.

3. Do not use excessive top (10 to 15kHz) boost, this will add mostly hiss to the sound as there is very

little signal output at this frequency from a bass.

The 30Hz slider has been provided to allow precise tailoring at very low frequencies.This slider should be used

to CUT (not Boost) the 30Hz to a level that allows the speaker system to work at its maximum efficiency.

USEFUL OBSERVATIONS

The fundamental frequency range of a regular, four string bass guitar is from 41.2Hz (bottom E string) to

around 392Hz (two octaves up on the G string) – not a very wide range. Obviously a lot of harmonics are

produced when playing and these can extend up to 5kHz and more.

The attack portion of the note also produces other high frequencies when the string is first struck.This

attack can be emphasised by boosting the top end. However because of the fairly small range of

frequencies from a bass, by top end we mean between 2.6kHz and 5kHz.You will find that by boosting at

5kHz the attack will be emphasised whereas by boosting at 1.3 and 2.6kHz you will bring out the

harmonics in the note.

Above this frequency range you will find it is better not to boost the signal as this will mainly emphasise

any hiss present.This hiss will not be masked by the bass signal when playing due to the very small amount

of bass guitar frequency content at 10 to 15kHz.

Use the 30Hz and 40Hz sliders sparingly unless you have a massive stack of speakers available, and the

power amplifiers to drive them.You will find that rolling off the bottom end by using these two sliders will

allow you to play at a far greater volume level without the speakers complaining.

Try to keep the graphic sliders balanced around 0dB and in a smooth flowing curve from one slider to the

next, and remember that after adjusting the graphic you may need to re-set the INPUT GAIN.

The DI or DIRECT INJECT socket is a balanced, low impedance XLR output intended for connection into

the Microphone Input on one channel of a mixing desk.

Continued over

INPUT LEVEL

INSTRUMENT INPUT

#16241 - Mark King Manual 31/8/04 1:19 pm Page 5

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Ashdown MK500 User Manual Page 3

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