Assembly Instructions for Speaker Crossovers with included PCBs

Discussion in 'General Topics' started by Matt Grant, Jun 11, 2018.

  1. I thought I would throw this up here to perhaps answer some questions people may have during crossover assembly and help cut down on the number emails Erich or I receive on this topic.

    General instructions:

    Place the crossover components (and terminal blocks if applicable) on the PCB in the positions referenced on the included image making sure that the connection leads are inserted into the correct through holes. Note all of the crossover components are non direction or non-polarized so the resistors and capacitors can be placed in either direction on the board. Many of the inductors/coils have the leads on one side so they often fit only one way on the board.

    Note: Sometimes the components may not visually match ones in documented photos of the crossovers boards due to parts availability at the time of order. Therefore components may be substituted for another equivalent part by a different brand. Note the voltage ratings on capacitors may differ but performance of the finished crossover will not.

    Secure components to the PCB using adhesive to prevent rattling and to prevent excess strain on the lead wires, hot melt glue works well for this. In addition use non metallic zip ties on the larger and heavier components.

    After securing the crossover components to the board you can flip it over and solder the component leads to the solder pads. It’s often easy to leave the leads pointing straight through the PCB when soldering and trim the excess lead length with side cutters when finished. Pay special attention to the leads of the inductors/coils as only a section at the ends of these are pre-tinned (silver colored), the rest of the lead length being insulated with an enamel coating (usually gold or red colored). You can only solder to the pre-tinned end of the leads as the solder will not make an electrical connection through the enamel coating resulting in degraded or no sound. If you wish to trim those leads shorter to make the installation cleaner you must scrape the enamel coating off the trimmed ends of the leads. Scrapping sideways with a utility knife works well.

    When the components are soldered to the PCB and the leads are trimmed you can connect the wires for the respective drivers and the input to the crossover board. Usually 16 gauge wire is all that is needed for the internal connections. If you have an older style PCB these wires get soldered to the PCB itself in a similar fashion to the components leads. If you have a newer PCB these wires get attached to the terminal blocks.

    Terminal Block ID:

    IN – The input to the crossover board from the speaker cabinet binding posts/terminal cup.

    LF – Connects to the woofer driver/s

    MF (if applicable) – Connects to the midrange driver/s

    HF – Connects to the high frequency driver or tweeter.

    HF PAD (if applicable) – Terminal block for the optional high frequency padding which lowers the level of the high frequencies. Connect a small jumper wire across the two positions of this terminal block to enable.

    For designs using the larger terminal blocks (Philips head screws) you can insert bare wire or use ring or fork terminals on the ends of the wires. For designs that use two drivers in parallel you can insert two sets of wires (one for each driver) into each position (+ & –) of the terminal blocks, (a bare wire should fit on each side of the screw).

    For designs using the smaller terminal blocks (flat head screws) these accept only bare wire (up to 12 gauge). For designs using two woofers in parallel there will be an extra terminal block to accommodate the additional pair of wires.

    Unless noted on the reference image or crossover layout instructions any polarity reversal of the drivers is accounted for on the PCB itself and the drivers should be wired to the terminal blocks as marked.

    With the crossover assembled and the wires attached you can now mount the crossover board. Many of the newer crossover PCBs include snap in standoffs which can be popped in from the bottom side at the four corners of the crossover board. Using the included screws the crossover board can then be mounted to the inside of the loudspeaker cabinet.

    The crossover should be installed before the damping material, it is ok to place damping material over the top of the crossover but for most designs it is unnecessary to cover the crossover.


    Quick checklist, are the wires from the input and individual drivers connected to the correct terminal blocks and or correct position on those terminal blocks and attached securely? Are there any loose strands of copper wires near the terminal blocks that are touching each other and shorting out? Is the crossover board mounted to a non conductive surface such as directly to the cabinet walls, not something like foil backed damping material? Are there any cold solder joints? If you suspect a cold solder joint it does not do any harm to heat the joint back up and allow the solder to reflow.

    Common problems and solutions:

    - Intermittent or crackly sound from speaker?
    Check for cold solder joints on the PCB which may be vibrating and making intermittent electrical contact. Also check for general loose connections to the crossover and or speaker terminals.

    - No sound from woofers?
    Check for loose connections to the terminal blocks. Check for cold solder joints. Check that the solder joints to the inductors leads are not made on the insulated enamel coated section which would not allow power/sound to pass.

    - Dull sound/no sound from tweeter?
    Check for loose connections. Make sure the tweeter is connected to the correct terminal block and that the input and woofer wires are not reversed.

    - Thin sound and/or tweeter extremely bight?
    Check that the resistors are placed in the correct positions on the PCB. Check that there are no cold solder joints on the bottom of the PCB. Check that the input and tweeter wires are connected to the correct terminal blocks and not reversed.

    - No sound from speaker at all?
    If you have already checked all solder joints and electrical connections on the PCB verify you are receiving an audio signal from the amplifier by substituting in a known working speaker.
  2. Crossover Assembly Example Videos:


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