Aesthetix IO User manual

Io with Volume Controls
One Phono Input & One Line Input
Rev 1.20 2019-11-27
1
Important Note One: Never change inputs between line and phono with the volume controls
up. Always ensure the volume controls are at their minimum (fully counter-clockwise) setting
before changing inputs. Unless the volume controls are at their minimum setting, a loud
discharge will occur that can potentially damage speakers.
An Io with volume controls configured with one phono input and one line input can have two Aux Input
boards (one for left, one for right) shown at the rear of the unit in the below photo (right).
The picture below shows a close-up of the Aux
Input board.
A traditional line section has the following structure:
Volume control – gain stage – output stage
It is nearly impossible to overload the gain stage with the above structure. However, the noise level
remains constant regardless of volume setting.
The gain structure of the line input section of Io is:
Gain stage – volume control – output stage
The gain stage can be overloaded with this structure, leading to high levels of distortion. However, the
noise level of the gain section is attenuated by the volume control, leading to extremely high signal to
noise ratios (low noise). The Aux Input board provides attenuation tailored to the connected source
component (CD player, etc) to prevent overloading the gain stage. When properly configured, this
structure leads to extremely high levels of performance from the line section.
Important Note Two: Never change the below settings with the Io on. Always turn off the Io
and wait 20 minutes before altering internal settings. This allows the power supplies to fully
discharge. If in doubt, refer to your qualified Aesthetix dealer or the factory.

Rev 1.20 2019-11-27
2
The red arrow indicates where the user can configure attenuation jumpers. The upper and lower settings
are labeled “0”, or no attenuation. Locate both jumpers to the “6” positions for –6dB; “12” for –12dB or
“18” for –18dB. Both jumpers for each channel should always be set to the same attenuation. Both
channels (left and right) should be set to the same attenuation. There are four jumpers in total. These
are most easily changed with needle-nose pliers or tweezers.
The below chart indicates the recommended attenuation settings according to the source component
connected:
Source Output Voltage
(Balanced) Recommended Attenuation Typical THD (ref 1V out bal) Overall gain at max volume setting
<500mV 0dB .05% 30dB bal in – bal out
500mV – 1V -6dB .05% 24dB bal in – bal out
1V – 2V -12dB* .05% 18dB bal in – bal out
>2V -18dB .05% 12dB bal in – bal out
*Factory default setting
Important note: By default older units do not have the Aux Input board. A fixed attenuator was installed
of -18dB. Those units can be upgraded by having the Aux Input board installed.
The blue arrow points to a 2 position jumper setting used to select a floating or grounded input for the
RCA connector. Typically it should be set to GND, or its lower position. This is the factory default.
The black arrow points to the Bal/SE jumper setting. When the Single-Ended (RCA) input jack is used,
this jumper should be set to SE, or its upper position. Set it to BAL, or the lower position when the
Balanced (XLR) jack is used. BAL is the factory default position.