Meyer Sound Documentation

DC current draw for Ashby loudspeakers is dynamic and fluctuates with changing operating levels. As the cable length increases between an Ashby loudspeaker and its external power supply, so does the resistance, which can eventually cause a voltage drop at the loudspeaker. This can compromise amplifier performance, peak SPL, and frequency response. The next section shows how to select the right cable gauge for each loudspeaker.

The maximum cable length depends on the type and number of loudspeakers looped and the gauge of the cable. Table 1 shows the maximum cable length for Ashby loudspeakers using 18 AWG cable with only 1 dB of peak SPL loss.

Using 18 AWG wire, a single Ashby-5C loudspeaker can use up to 450 ft of cable (300 ft for Ashby-8C) from the MPS Power Supply and lose no more than 1 dB of peak SPL. Unlike 70 V line-distributed loudspeakers, Ashby loudspeakers do not suffer gain loss with the long 18 AWG cables.

The table below shows the maximum cable runs for a single channel of an MPS Power Supply powering up to 3 Ashby-5C or two Ashby-8C with different wire gauges. The last table below shows the same information for European cable gauges.

*Also applies to one Ashby-8C with one looped Ashby-5C

*Also applies to one Ashby-8C with one looped Ashby-5C

The maximum total cable resistance between one Ashby-5C loudspeaker and its external power supply is 6 Ω, and 4 Ω for one Ashby-8C.

When using the maximum number of loudspeakers per channel (3 Ashby-5C or 2 Ashby-8C), it should not exceed 2 Ω.

The maximum cable length for an Ashby loudspeaker can be calculated using the formulas shown below. The Wire Resistance Per Foot (WRPF) is the resistance (in Ω) for one foot of individual wire of the chosen gauge. Enter the WRPF in the equations below to determine maximum cable length. The equations compensate for round trip length.

For 18 AWG, WRPF = 0.006385 Ω/ft

Ashby-5C: Maximum length (ft) = 3 Ω/ (WRPF x # of Ashby-5C)

Ashby-8C: Maximum length (ft) = 2 Ω/ (WRPF x # of Ashby-8C)

To calculate the maximum length in meters, substitute the

Wire Resistance per Meter for the selected wire gauge.

The Belden 1502 multiconductor cable is an effective, convenient way to connect an Ashby loudspeaker system. DC power and balanced audio use dedicated conductors in a single cable jacket. Table 4 shows the wiring conventions.

Belden 1502 multiconductor cable

If your installation does not allow using Belden 1502 multiconductor cable, or requires cable runs longer than 150 ft, use separate cables for DC power and balanced audio (see Cable Length and Gauge). Use a high-quality, balanced cable for audio. Attach the separate cables to the Phoenix connector as shown in the figure below.

Note the orientation of the connector while assembling the cable. This view shows the screws facing you.

Separate Cables for DC Power and Balanced Audio

When powering on the Ashby loudspeaker, the On/Status

LED indicates the following startup events:

The On/Status LED turns yellow to indicate limiting. When engaged, the limiter protects the loudspeaker's drivers and prevents signal peaks from causing excessive amplifier distortion, thereby preserving headroom and maintaining a smooth frequency response at high levels.

When source levels return to normal, below the limiter threshold, the LED turns green and limiting ceases.

The Ashby performs within its acoustical specifications when the LED is green, or when limiting is not continuous.

If limiting activity is continuous, the loudspeaker is near its operating limits where:

The On/Status LED lights red when the loudspeaker's input stage clips, causing the amplifier to overload. Reduce the source level to avoid distortion and overloading the amplifier.