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.
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
PALMER PLI-03: THD ACCORDING TO THE INPUT LEVEL
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
PALMER PLI-04: THD ACCORDING TO THE INPUT LEVEL
PALMER PLI-06: FREQUENCY RESPONSE
PALMER PLI-06: THD ACCORDING TO THE INPUT LEVEL
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
– Gold-plated RCA connectors
– Manufacture quality of the components
– Range of products
– Five-year guarantee
Value for money:
You can find all of the technical specifications at the following address:
Source: SONOMAG Magazin, France, April 2012