- Volume/Tone Stack
- Active Stack
- Black Finish
The P-Retro is a simple but flexible active/passive bass preamp equalizer which offers huge tonal variation to one of the most popular styles of bass of all time, without the need to permanently modify the instrument itself. P-Retro features two stacked knobs each with a pull-switch, class A FET input stage and a high quality relay for pure passive bypass.
Power is provided by an internal rechargeable battery. The normal volume control becomes the Volume/Tone Stack and works in exactly the same way as the P style bass original controls, passing the passive signal directly to the jack. When the volume control is pulled up, the active circuit is switched in, post passive tone control, and adds 2.5dB of gain with a flat response. Additionally, the upper knob allows either a mid boost, or a combined bass/treble boost. The lower knob sets the variable frequency points for either mode.
The P-Retro is based on a novel dual mode circuit which has a flat response setting, a conventional variable frequency mid range boost, as well as a combined bass/treble boost. A 'deep' setting is available too, as well as a bright option.
Please Note: In regards to knob rotation:
CW = Turning a knob up towards maximum or clockwise
ACW = Backing a knob off, turning it anti-clockwise or counter-clockwise
- Volume In Passive (Upper Knob Pushed Down)
- Volume In Active (Upper Knob Pulled Up)
- Passive Tone (Lower Knob in both Active & Passive Modes)
- Dual Boost Knob (Upper Knob Pushed Down)
- Dual Boost Knob - Deep (Upper Knob Pulled Up)
- Lower Frequency Knob (250Hz - 2kHz)
Works purely passively at all times and is designed to function exactly as the standard Volume and Passive Tone in a P Style Bass. This is in order that the wonderful stock sounds are always available, with no compromise.
When the upper knob is in its down position, the system is bypassed via a high quality relay with gold plated contacts. In this case, the jack is fed directly from the output of the Volume, exactly as a standard P Style Bass.
When the upper knob is in its up position, the active circuit is in activated and the output of the volume feeds the input to a class A FET input stage. The audio is passed through the active stage and its output feeds the jack with a low impedance signal.
Acts directly on the pickup at all times, exactly as in a standard P Style Bass, playing a totally familiar role.
The Passive Tone is also extremely useful in the active mode, further allowing the treble content of any active boost to be suitably backed off or subtly tailored. The Tone Capacitor plugs in, easily allowing different values.
In its centre click, there is additional gain of 2.5dBs with an essentially flat frequency response. (Additionally there is an option for a slightly brighter sound by setting an internal switch to on, described in the installation set-up.) Turning it CW gives a mid boost ranging from 0 - 15dBs at frequencies according to the setting of Frequency knob. Turning it ACW gives a combined boost to the bass and treble spectrum. The lowest level point is set by the Frequency Knob, but the amount of bass and treble boost varies according to the setting of the Frequency knob. (Not easily described in specification terms)
Pulling up the Boost Knob activates a Deep setting. There are four frequency settings for the Deep Boost, set via switches on the circuit board - 40Hz, 60Hz, 80Hz & 100Hz. The Deep Boost level is also adjustable via a preset trimmer.
Please Note Important:
The Deep switches and level preset are placed on the circuit board such that, if six of the pickguard screws are removed, the pickguard can be eased up in order to gain access for adjustment while the bass is fully playable.
The lower outer knob has 41 click positions to set the frequency of operation for the upper knob. Turn ACW for the lower frequencies and CW for the highest frequencies.