PRSS delays fix for audio levels

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The Public Radio Satellite System has postponed by several months its plan to change the level at which it provides audio to member stations, allowing more time to deal with unanticipated complexities of the switch.

The adjustment to PRSS’s technical standards, announced in December with a short timeline for implementation, rolls back a 2013 change that was intended to correct an issue with new receiver equipment provided to stations, the IDC SFX 4104 Pro receivers. Because the analog outputs of the receivers operate at a lower level than those from the previous generation, PRSS added a six-decibel boost to its overall audio levels to its uplinks.

Though the audio boost restored analog output to more usable levels, it reduced the range of levels available in the audio chain and created the potential for distortion of some louder audio passages.

To correct the problem, PRSS began preparations to remove the six-decibel boost by Feb. 26. But one day before the change was to take effect — Feb. 25 — PRSS pulled back from implementing it.

The fix that initially appeared easy — turning the level back down and asking stations to turn it up at the receive end — became more complicated after PRSS learned how many variables exist among the 420 interconnected stations as well as the producers who feed content into the system.

“There were two factors we had to deal with,” said Erich Shea, PRSS planning and communications manager. “It was very clear that there were still a handful of stations that were not ready. There were some technical issues that were unique to the stations having the problems. And, on our end, there was the thought that we need to make sure this is done correctly, and that we need to take into account all aspects, including live-with-subsequent-file-transfer, or LWSF.”

LWSF programs, which include staples such as Fresh Air, are sent out both as live feeds over the PRSS satellite and as audio files that stations can play back hours or even days later. The multiple feeds add an extra layer of complication to adjusting the audio level, since files sent with PRSS’s six-decibel boost could be broadcast out after the change kicks in.

The discrepancy presents an extra challenge to stations with small operations and engineering teams because they may have to adjust some of those levels manually.

(Removal of the level boost is not directly related to the larger PRSS initiative to establish a consistent loudness standard for all of its programming, a process that’s still underway and will be discussed at next month’s Public Radio Engineering Conference in Las Vegas. “They’re in the same neighborhood, but they’re not connected and we’re not viewing it that way,” Shea said.)

PRSS is also taking extra time to work with local stations to make sure their own local programming properly matches incoming national feeds so listeners get a consistent experience.

“From our perspective, the entire station community had not absorbed that,” Shea said of the complex process, “so it was determined that if we put that on the back burner, there are some steps we can take to make sure the process goes more smoothly than if we pulled the trigger tomorrow.”

Since delaying the change, PRSS launched a seven-step process to ensure all PRSS users are ready when the new levels finally take effect, likely in late summer. PRSS also must work closely with all the outside producers who feed material into the system.

“We have a dozen producers hitting us with live traffic,” said Mike Beach, PRSS v.p. of distribution. Those include producers for NPR, Public Radio International, American Public Media and local stations such as WBUR in Boston and WAMU in Washington, D.C.

“We think it will take us a couple of months to work through this with producers,” Beach said. PRSS will run tests on every show’s feed, ensuring that there is “unity gain” from the producers’ end to the output from receivers at PRSS client stations. Audio levels are supposed to remain consistent all the way through the distribution chain — from the program’s origination point through stations’ receivers.

To help stations prepare for the switch, PRSS will run extensive test streams so engineers can get their equipment ready to handle the lower output levels from their receivers. At the local level, that may mean adding amplifiers at the receiver output or tweaking input settings on consoles or automation systems.

PRSS is aware of specific issues at remote stations that must be addressed, Beach said, including those in rural areas that may require in-person visits from engineers based elsewhere. For the most part, though, he thinks stations will be ready once the levels are finally adjusted.

“I don’t know how much more vocal we could have been,” he said. “Beyond asking questions generically, we reached out to individual stations” to ensure they’re ready.

“I’m sure people have jumped through a lot of hoops to get ready, and I hope they don’t see it as wasted time. We’re sorry for pushing it off, but we want to get it right,” he said.

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  • paulakiger

    I love Jessica Hansen’s voice! Whatever the “special projects” are, I wish Sabrina Farhi the best.