Power Bridging

In the past, amplifier channel "bridging" has been offered as a way to take two channels of an amplifier, and "glue" them together to make a single channel with double the rated power. This can be handy, especially for driving subwoofers. Traditional drawbacks to bridging have been that it is something that must be selected and specifically wired on the amplifier at installation - requiring physical access to the amplifier to modify in the future.

Enter Smart Power Bridge

LEA has taken bridging to a new level with their Smart Power Bridge feature - and it is all selectable via the amplifier's web interface (or via Sharkware) and can be enabled/disabled at will. Smart Power Bridge does not require specific wiring at the amplifier - simply wire the channel as you normally would for a normal load.

How It Works

When Smart Power Bridge is enabled, the software effectively doubles the power output on that channel. It does this by applying a 15% reduction in power output across the remaining channels, and directing this to the Smart Power Bridge channel. There is also some magic borrowed from the amplifier's ability to drive 100v rails in Hi-Z mode - all resulting in a channel with twice the output. The 15% reduction in power on the non Smart Power Bridge channels is describing the amplifier at maximum effort, all channels driven at full power (a rare instance with FlatPanel Audio and LEA.) In reality - such as when driving DMLs, the max power peaks are simply brief transients, that the LEA's power supply can likely still deliver at full channel power.

Usage with FlatPanel Loudspeakers

This feature is a huge win for many FlatPanel installations - it's the subwoofers that truly benefit from the Smart Power Bridge feature. A common configuration being two DML500's in a Left/Right configuration, with one of the 3 FlatPanel subwoofer options (LS208, LS212, or LS118) on the remaining channel (s.) This configuration is commonly driven with an LEA CS704, or in higher SPL applications (and in our Demo System) the CS1504.

Smart Power Bridge Applications

CS704

In the CS704 example, enabling Smart Power Bridge on the subwoofer channel yields 1400 watts for the subwoofer. This leaves almost 600 watts available on the other three channels, which is plenty for a DML500 in most cases. Keep in mind this is a configuration that will fill a medium sized room with full sound out of 1 rack space! And, this configuration only uses three channels, leaving you with a 4th channel of nearly 600w for other uses, such as a monitor, or lobby zone - with plenty of power supply energy left to handle the peak transients. If you don't use that 4th channel, that leaves all of that power supply capability for the other channels.

CS1504 

LEA's CS1504 is the standard recommended amplifier that ships with our demo kit, and it is our recommended amplifier to use when maximum SPL is needed from either the DML500, or any of our subwoofers. This amplifier will support larger rooms with the full energy needed for live bands with ease. In the case of the demo system, we ship the amplifier configured with Smart Power Bridge enabled on both channels 3 and 4, so the amplifier is ready for more than one subwoofer. In this configuration, the DML500 channels 1 & 2 receive 1050w each, and the two subwoofer channels receive 3000w each. The 30% reduction of power on the non Smart Power Bridge channels (15% x 2 Smart Power Bridge channels on the CS1504) is with all channels driven at maximum - under nominal loads, this reshuffling of power ends up being all benefit to the subwoofer channels, with very little noticeable power loss on the non Smart Power Bridge channels.  And all of this from a single 2 rack space amplifier, on a single 20A 110v circuit (see our other articles on amplifier selection and power practical power consumption.)

Note: there is a little bit of LEA power supply magic going on underneath - while each channel with Smart Power Bridge enabled officially takes 15% away from the remaining non Smart Power Bridge channels, if the Smart Power Bridge Channels are not being run at full power, nearly full power is still available for the non Smart Power Bridge channels. In addition, with most FlatPanel Audio implentations, the Smart Power Bridge channels are usually running completely different content (sub/LF content) than the non Smart Power Bridge channels (main content), so again there is plenty of energy in the power supply to deliver nearly full channel power transients, since the power supply is not being called upon to deliver full power to all channels simultaneously. This is why enabling and disabling the Smart Power Bridge feature with a normal FlatPanel configuration of 2 DML / 1-2 Subs, you may not even notice any reduction in SPL on the non Smart Power Bridge channels.

Isn't a DML500 rated at 600w Program?

Even though the DML500 is rated at 600w program power, with our dedicated LEA Speaker Tuning Files - we have limiter settings preconfigured to protect the loudspeaker, and we are able to drive the DML considerably over its rated power for short bursts (transients.) This is part of the amazing clarity that comes from DML - by using an oversized amplifier channel on the DML, we are able to deliver these transients to the DML while remaining well below the amplifiers maximum rated output, ensuring clean power. And DML500 does not create measurable 3rd order harmonic distortion, so these transients come through clean and clear, a hallmark of the FlatPanel DML500/LEA combination.

Other Configurations

Smart Power Bridge is available across all models in the LEA Professional lineup, even in the 1/2 rack 2 and 4 channel product line.  You can power two DML500's and an LS208 subwoofer quite well for a small background music system with a 1/2 rack space LEA CS124 amplifier. With Smart Power Bridge enabled on the subwoofer channel, the LS208 would receive 240 w, enough for a small space. A single Smart Power Bridge channel is provided on all models except the CS1504, which allows two Smart Power Bridge channels.

In summary, Smart Power Bridge is an extremely handy feature that works well with FlatPanel loudspeaker configurations, often allowing a single amplifier to drive both main and sub content.  In real world usage, Smart Power Bridge is all benefit with minimal, if any, down side.

If you have questions or would like help designing other more complicated amplifier configurations, please contact us!

Read more about LEA's power management features here