Proper Audio Control Amplifier (CA-1)
The Proper Audio CA-1 is a high performance Control Amplifier (pre-amplifier), and should be considered the 'heart and brains' of any Proper Audio system. Whilst optimised to work perfectly with any Proper Audio amplifier, the CA-1 will work perfectly well with any amplifier with an unbalanced (RCA) input.
Low-noise
The CA-1 was designed from the outset to be a low-noise design, this has been achieved using various techniques - the first being to apply gain using ultra-low-noise circuitry so that the signal is as robust as possible before being routed through the switching and volume control circuitry. Use of paralleled amplifier stages keeps noise to a minimum and improves linearity.
Dual Mono Architecture
Designed using a pure "Dual Mono" approach (including the use of separate power supplies for each channel), each channel - left and right - has a separate circuit board containing the switching and attenuation circuits, keeping channel separation at its maximum.
Ease of Use
With only one control on the front panel, operation of the CA-1 really could not be any easier. By default, rotating the control dial adjusts the volume up and down. A single press of the dial switches to "Source", where you can select any of the inputs by rotating the dial. A 3 second press mutes the output, whilst a long press puts all the units into standby mode.
Attenuator
Conventional volume controls using a potentiometer are inherently compromised not just in terms of noise and channel separation, but also channel balance accuracy. The CA-1 makes use of a unique attenuator made up of a bank of switched resistors, rather than the typical potentiometer. This is not unique in itself, but how we implement it is.
Depending on the volume setting, in a typical 'ladder' attenuator the signal passes through the required combination of resistors, to achieve the required values. Depending on the setting it might be as few as two or as many as eight resistors. This uncertainly results in potential variations in the character of the sound. Using an algorithm developed by Proper Audio, we were able to design a switched attenuator that only ever routes the signal through a maximum of 2 resistors, keeping the sonic character consistent, regardless of the volume setting.
There are 72 steps from the minimum setting (mute) to full volume - each step equating to 1dB. Normally this would require several turns of the dial to go from quiet to loud, and would clearly be impractical, however we have developed a control that detects how fast the dial is being turned, and increase the step size appropriately. so a quick half turn will result in large step sizes increasing the volume quickly, but the same half-turn done slowly will allow precise level setting. The actual volume level is displayed on the main display.
As an added convenience and safety feature, if the volume control was left at a high setting when last used, it will automatically reduce to a pre-set, safe level when next switch-on. Similarly, we have included automatic reduction of the volume level when you select a new source. When you change the source, for example from 'Line 1' to 'Line 2', the system first reduces the volume from its current setting, changes the input source, and then ramps the volume back to the original level. This saves you from getting a surprise if the new source is a lot louder than expected! If, as the level starts to return to its previous setting, you decide it is loud enough, you simply need to rotate the dial by one 'click' and it will stop at its current level.
Dual Pre-Amp Output
The CA-1 has two sets of outputs - this is so that you can connect it to both a Proper Audio Power Amplifier and to the Proper Audio Headphone Amplifier - when you plug in your headphones the power amplifier will be muted and placed in standby.
Systems Comms
The CA-1 will detect any Proper Audio kit you have plugged in to its "Comms" system, and configure itself automatically. Depending on what has been added, this will update the display to reflect any new functions that are available (e.g. "Phono Stage" instead of "Line 1"). It will also add these devices to the power management routines, so that all devices are put into standby mode as and when required.
Specification
- 4 Line input (RCA) max input tba mV
- Distortion and Noise
- 2 Pre output (RCA) - to Power Amp and Headphone Amp
- Dimension 453(w) x 92(h) x 430(d)
