Since 1993 Copyright Notice

EE24. Gold Plated Bidirectional XLR <==> RCA.

LL1527, LL1527-XL, LL1570, LL1570-XL, LL1540, LL1545, LL1578, LL581-XL.

Other small signal Boards

Introduction

• Order nr: 310-024-89
• Dimensions: 56 x 37mm
  

Possibilities:

Bidirectional use. Each side can be used as input or output

1. XLR INPUT: Add a balanced, symmetric XLR INPUT to an amplifier with standard (unbalanced) RCA input. XLR1 of the XLR connector is grounded directly at the connector itself. XLR1 of the PCB stays unconnected for this application.
2. XLR OUTPUT. Add an balanced, symmetric XLR OUTPUT to an amplifier which has an RCA output. Normally, XLR1 of the XLR connector is grounded directly at the connector itself. Alternatively XLR1 of the connector can be grounded at the PCB, and not at the XLR connector itself.
3. RCA INPUT. Add an RCA INPUT to an amplifier with XLR input in parallel, without loosing the balanced property of the XLR input. This is a special case, where balanced XLR must work normally, but you want a standard, unbalanced RCA connector in addition. In this case, XLR1 is not connected to the PCB.

Grounding of the PCB. The ground of the RCA side, XLR1, and the PCB ground plane, these three are connected to each other. The PCB ground is grounded to the chassis, via the mounting screws. However, since screws of a PCB always tend to loosen after many years, this connection can become unrealiable. To prevent this, the ground of the RCA side ideally is connected with a short wire piece directly to the chassis.

This board uses 1:1 transformers, which have an attractive price.

Just connect the board, and it works.

The board can be used with a few different transformers, each with it's own advantages. (Listed below here). The difference of those is signal level or frequency range.

If signal level is not much higher than 1Volt AC, also Board EE31 can be used, which uses the low cost LL1531 transformer. This is a good transformer as long as audio range of 10...25kHz is required, and only 1Volt signal. For higher signal and extended frequency range, the transformer of this board EE24 are used. In the table below here, signal level and frequency range is given.LL1570 us the frequency range champion.

Tuning

• If the input is at the RCA side, the tuning network is only Ra and Ca.
• If the input is at the XLR side, the tuning network is only Rx and Cx.
• Parts Values are in the table below here.

Exceptions:

• No solder bridges are used for L1570, LL1570-XL, LL1540, LL1545 and LL1578.
• LL1527 and LL1581 need only a resistor. For those two transformers, both solder bridges at the PCB Back side are closed.
• With tuning, the frequency range is as in the table. Without tuning is also possible, in that case the high frequency is appr 3/4 of specification. Low frequency is the same.