DISC Ashdown Envelope Filter Bass Pedal

Full Description

An Envelope Filter effect is simply a variable Band Pass or Low Pass electronic filter circuit where the 'sweep' through its filter range is controlled by the level of signal passing through the unit. In other words the device is dynamically controlled by the player i.e. the harder the note is played the greater the frequency range through which the sweep of the filter passes. This Sweep can usually be chosen to be in an Upward direction i.e. the filter frequency increases with an increase in signal level or in a Downward direction i.e. the filter starts at a high frequency and sweeps downward with the degree of sweep following the signal level. It is important to set the Input level to the correct reading on the VU meter as this will affect the range and sensitivity of the envelope filter.

PEAK

The Peak control adjusts the sharpness of the Peak or "Q" of the filter response. Increasing the setting of this control gives a much more emphasised range of filter harmonics in the instruments tone. Use the low range for more natural sounding filter sweeps and the higher settings for more exaggerated filter effects.

UP/DOWN

The Up/Down control determines if the sweep through the filters frequency range is in an Up direction i.e. the frequency of the filter increases as the note is played harder, or in a Down direction i.e. the filter starts at a high frequency and sweeps downward as the note is played harder. In most Envelope Filter pedals this is a switched selection i.e. you can choose either Up or Down.

What we have done is to provide you with a variable degree of both the Up and Down ranges on a single rotary control with fully Up at one end of the control and fully Down at the other. With the control in its centre position there is no sweep effect at all, this is zero setting for both Up and Down. Turning the control clockwise from its centre position gradually increases the Down sweeping range whilst turning anticlockwise from its centre position gradually increases the Up sweeping range. It is therefore possible to precisely adjust the degree of either the Up or Down frequency sweep exactly to your liking.

BP/LP

BP/LP stands for Band Pass or Low Pass filter frequency responses, Band Pass is like a Wah-Wah where a narrow band of frequencies is swept through with the filter rejecting all frequencies either side of this pass band. Low Pass is like a very powerful Treble control i.e. when turned down you hear only the low frequencies and as the frequency range is swept upward the mid and then the high frequencies are added to the low frequencies. In a way Low Pass is more useful for bass as the low frequencies are always retained within the sound, however Band Pass is a more exaggerated effect but makes the sound too thin at the high frequency end of the range. Usually an Envelope Filter will offer you a switched choice of either Band Pass or Low Pass but what we discovered was that mixing the two together provided a much more useful sound than either one alone. We have therefore made the BP/LP control work in a similar way to the Up/Down rotary control i.e. one end of the control is fully Band Pass and the other end of the control is fully Low Pass, thus anywhere in-between is a mixture of the two, with the centre position being equal proportions of Band Pass and Low Pass.

Technical specifications

Filter Range

• 30Hz to 12kHz
• Filter roll off 24dB/octave

Filter Peak

• Q Infinitely variable from 3 to 10

BP/LP

• Single rotary control selects BP, LP or a continuously variable mix of both

Up/Down

• Up & Down ranges continuously variable from zero to full sweep

Input

• Impedance 470k Ohms
• Signal level ?10dBv to 0dBv

Output

• Impedance 10k Ohms
• Signal level variable ?10dBv to 0dBv

Supply

• Internal 9v battery
• External supply 9v DC adaptor. Centre pin negative.