Training Tips

Training Tips




Why is it So Hard to Turn on My Home Cinema?


By Tom Pfister
Field Support Engineer

Home Cinema Control: As today’s Custom Home Cinemas grow more complex, be prepared for the boot up requirements to increase as well.

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The JBL Synthesis flagship SDP-75 Surround Sound Processor is often part of large whole home High Definition Multimedia Interface (HDMI ) distribution systems that route audio and video from shared sources throughout the home. With the very long wire runs sometimes required to do this, installers will commonly use Baluns or HDMI signal converters to convert the HDMI signal to category 5/6 wire, which allow for extension of the HDMI signal over very long distances. One example of this is connecting the AV signal from the SSP to the display/projector, which is commonly quite far from the AV rack. With all this equipment interconnected through HDMI, they are required to maintain constant bidirectional communication with each other. In order for this to happen, each HDMI component needs to be powered up in the correct sequence so that it can properly communicate with the next HDMI product in the system chain.

The correct sequence for HDMI devices to be powered on is in the opposite direction of signal flow. A simple example would be: TV/ Projector first,  SSP/ AVR second, source devices get powered up last. This communication hierarchy is built into the HDMI interface, and although it is always recommended it seems to be rarely followed. Since the television, display, or projector is the ultimate destination for the video signal, this device needs to be fully powered up in order to send and receive communication from the other HDMI devices. Once powered up it will actively communicate its capabilities over the HDMI network so that the next device in the chain receives the information and adjusts its output accordingly to provide a compatible AV signal. There is great variation in the way HDMI products are built and programmed, which means required power up delay times will vary from product to product.  Yes, the devices can “time out” and stop listening or sending this information after a period of time.  What a headache!

Well, we’re fans of making it easier. One easy way to do that is eliminating the need for a ton of remote controls (some systems have as many as half a dozen, most required for operation) by opting for a home automation/control system to simplify power and control.

It is also important to be aware of and adhere to any product-specific connectivity requirements.  The aforementioned SDP-75 for example, comes out of the box with HDMI inputs 1-3 configured for HDMI v1.4 to provide legacy device support.  HDMI inputs 4-7 are configured for HDMI 2.0/ HDCP 2.2, allowing full support of the latest UHD/HDR devices.  This is not uncommon and absolutely should be checked prior to installation. Also, ensure that the firmware is current for the equipment you are installing.

Another way to simplify the use of your intricate system is to avoid the use of HDMI adapters, baluns, or signal manipulation boxes whenever possible. These additional conversions generally lengthen the power up sequence and add more delay to the overall communication time in the system. This can lead to communication errors which can result in “no A/V” conditions that can prove difficult and time-consuming to troubleshoot. Instead, we recommend the use of a 18gbps UHD/HDR HDMI cables whenever possible, and 18gbps fiber optic HDMI cables in cases where really long runs are required.  Please contact Field Support Engineering (csupport@harman.com) for HDMI cable recommendations.

It is also best practice to ensure that no commands or queries are being sent by the control system to the HDMI connected devices before they are fully powered up and ready. If the device is not ready to receive commands from the control system it will likely not respond correctly, slowing down the boot up process and triggering repeat requests from the control system. This type of “bogging down” is not only a waste of time, but also resources like memory or CPU power. Best practice for power will come from utilizing a power trigger to turn on & off the SSP, versus external commands that can also bog down the SSP with unnecessary in/out communication requests.

A few other things to keep in mind:

  • Synchronization is KEY in HDMI connected systems

  • Make sure you’re properly configured and your settings are applied correctly

  • This article assumes all products are working as designed and not suffering from hardware or software failure

Simplicity is usually best and we’re here to help you with it!