Palmer PLI-03, PLI-04 and PLI-06 multimedia direct boxes – Test Report by SONOMAG Magazine

These three passive direct boxes all share a similar appearance: robust rectangular casing made out of blue die-cast aluminium, with a classic design. The manufacturing quality of the three units is excellent. No surprises here. Of the three, the PLI-04 (PRO MEDIA model) is geared most towards multimedia. It has three types of input connectors (3.5 mm and 6.35 mm jacks and gold-plated RCA connectors) to two XLR outputs. It is a stereo unit, offering mono mixing, which can be selected by pressing a switch. However, as there is no input pad switch, you must remember to reduce to the output level on the device to which it is connected. The PLI-04 also has the classic ground lift switch, with an additional “Soft Ground” function, offering a high frequency filtering unit for ground loops. The transformers are shielded.

The PLI-03 and PLI-06 are known as line isolation boxes. The PLI-06 only has RCA (gold plated) inputs, a ground lift switch and a single XLR output connector (the stereo channels are therefore mixed to mono). The PLI-03, however, is one of the most basic boxes with only two sets of gold-plated RCA connectors as the inputs and outputs. The PLI-03 has permanent galvanic isolation: it does not have a ground lift switch.

MEASUREMENTS
The measurements show that the frequency response is compliant. The 1 kHz distortion is very weak and remains within normal levels at 40 Hz. At this frequency, one can observe that distortion increases more quickly when the level increases, which is a standard characteristic of transformers due to the faster saturation of magnetic material at low frequencies. The measurement results on these models are excellent overall.

PALMER PLI-03: FREQUENCY RESPONSE

A slight reduction above 7000 Hz, which indicates usage of a different transformer from the two other boxes.

PALMER PLI-03: THD ACCORDING TO THE INPUT LEVEL

The distortion level remains excellent, even at 40 Hz.

03: The PLI-04 with its multimedia input connector.
04: The ground lift switch, with an additional “Soft Ground” position, offering a high frequency filter for the two ground loops.

PALMER PLI-04: FREQUENCY RESPONSE

This model also demonstrates a perfectly linear response.

PALMER PLI-04: THD ACCORDING TO THE INPUT LEVEL

The level of distortion is still perfectly acceptable.

PALMER PLI-06: FREQUENCY RESPONSE

This model also demonstrates a perfectly linear response.

PALMER PLI-06: THD ACCORDING TO THE INPUT LEVEL

The level of distortion is still perfectly acceptable

05: Inside the PLI-04 with its two transformers and long mono/stereo switch, which ensures that the transformers are in parallel. On the left, the ground lift switch with its high frequency soft-ground filter.
06: The PLI-06 line isolator with ground lift switch.
07: The mono XLR output on the PLI-06

SONOMAG’S VERDICT

The pros:
– Gold-plated RCA connectors
– Manufacture quality of the components
– Range of products
– Five-year guarantee

Value for money:
Very good

You can find all of the technical specifications at the following address:

PLI-03:
http://www.palmer-germany.com/pro/en/PLI-03-Line-Isolation-Box-2-Channel-PLI03.htm

PLI-04:
http://www.palmer-germany.com/pro/en/PLI-04-Media-DI-Box-2-Channel-for-PC-and-Laptop-PLI04.htm

PLI-06:
http://www.palmer-germany.com/pro/en/PLI-06-Line-Level-Converter-2-In-1-Out-PLI06.htm

Source: SONOMAG Magazin, France, April 2012