Pass Labs X1 owner manual

X1 Owner’s Manual

If your signal source is unbalanced, input will always occur through the RCA input connector. Inputs 1 and 2 give you a choice or either single ended or balanced inputs. When single-ended inputs are used on input 1 and input 2, a shorting plug, which is provided, should be inserted between XLR pins 1 and 3 of the associated connector. This plug shorts the negative input to ground thus optimizing the input connection. You can run the X-1 without this shorting plug, but performance will not be ideal. (NOTE: inputs 3 & 4 are single ended only and do not have XLR’s associated with them.) You are free to use any combination of balanced and unbalanced connections with the X1. The unbalanced input impedance of the preamplifier is 33 kOhms. In balanced mode, the input impedance is higher, with a differential impedance of at least 66 kOhms.

Next to the inputs on the rear panel, the preamplifier offers tape inputs through both XLR and RCA connectors. This output is a direct connection to inputs 1, 2, 3, and 4 when they are selected from the front panel. Input 5 (TAPE IN) is deliberately not available through the tape output connection. Input 5 is designated for use with a tape recorder if you have one, and we have arranged that it will not place its output on the tape out, which will prevent you from accidentally creating a feedback connection with your tape machine.

The main outputs are located at the left-hand side (viewed from the rear) of the rear panel, two male XLR connectors, and two RCA connectors, “R” (right) and “L” (left). The RCA connectors ground is in parallel with pin 1 of the XLR outputs and the RCA hot is fed from an independent summing junction that maximizes the X circuit benefits. The RCA, single-ended, outputs are buffered from the balanced outputs. You may use both the single ended and balanced outputs at the same time. On the XLR, pin 1 is ground, pin 2 is positive, and pin 3 is negative.

The X1 takes maximal advantage of four identical gain paths (two identical paths per channel) very much unlike the typical two gain path (one signal path per channel) pre-amplifier you may be familiar with. Almost without exception traditional audio pre-amplifiers, unlike their science and industry counterparts, have maintained single signal path per channel (two identical paths in a stereo pair).

In order to manage balanced signals these two gain path pre- amplifiers must utilize phase combining networks to process incoming signals and subsequently drive outputs via phase splitting circuits to re-establish a quasi-balanced signal. This manipulation of signal typically adds additional gain stages and degrades the inherent

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