Detailed Operating Modes

A Visual Note

PDM II is an advanced time-manipulation tool for radio broadcasters. Since we can’t play audio in this manual, we’ll use graphics to explain how it operates.

These drawings might also help you visualize what PDM II is doing when you press its buttons.

• The top line (pink background) shows what’s happening in the studio and what’s heard by the talent and producer.

• The bottom line (blue background) shows the resulting audio that PDM II sends to the transmitter or network feed.

• The white slash through the blue line beneath the DUMP button shows where PDM has smoothly deleted material from the on-air program.

Note that we exaggerate and stretch the text to better illustrate how PDM II adjusts audio speed. In actual use, PDM II’s functions are a lot more subtle and most listeners won’t be able to tell they’re in use. They’re also user-adjustable, so you can fine-tune the sound to your programming and station’s style.

Building and Dumping

"Building" is the process of recording incoming audio to PDM II’s delay memory to create enough of a buffer to cover the gap during a Dump event. There are several ways to build as described below.

Primary Build Mode - Expanding

In this mode, the talent starts the program at the usual time, presses the Build button, and starts talking.  PDM II will subtly slow down the signal it sends to the transmitter (shown in red in Figure 1 below) while storing the real-time signal in its delay memory.

When the delay memory reaches a pre-set limit, PDM II’s output returns to normal pacing (shown in black), but the output is delayed by that pre-set amount to give you protection from objectionable material.

When the talent or a producer hears something unacceptable, they press the Dump button. PDM II mutes the delayed signal before the obscenity and instantly jumps back in its memory by a pre-set number of seconds. The talent can continue talking and the audience doesn’t hear dead air.

PDM II then automatically starts building up its delay again, and speed changes are virtually undetectable thanks to the algorithms we first developed for 25-Seven’s groundbreaking Audio Time Manager that intelligently splice individual soundwaves so that pitch isn’t affected and pauses aren’t unnaturally clipped.

Note: PDM II uses advanced time manipulation algorithms that don't affect pitch, add harmonic distortion or frequency limitations, or rely upon deleting pauses in the audio. As a result, it can be used on audio with continuous energy (such as music or live events with background crowd noise) and will never degrade your talent's delivery.

Using lower speed numbers causes the least amount of tempo change and are usually imperceptible but take longer to fill the delay memory or return to real-time.

Using higher speed numbers fills the memory more quickly but may cause noticeable speed changes on fast-paced material or cause an occasional doubling of fast consonant or drumbeats while the delay is building.  

Alternate Build Mode 1 - Inserting an Audio File

Setting the Build Mode to "Insert" and pressing Build plays a pre-selected audio file from its internal storage.

In this mode, the talent begins talking as soon as Build is pressed. PDM II  sends the studio signal to its delay memory while the audio file plays out to the transmitter. When the audio file finishes playing, PDM II begins playing the delayed audio and the Dump button can be used as needed as shown below in Figure 2.

Audio files can be uploaded to PDM II from a networked computer via the web GUI in the Audio Files page.  Multiple build files can be stored and selected as needed from the front panel or remote user interface.

If the selected build file is exactly as long as the Delay Size, PDM II will smoothly join delayed audio at normal speed when the file finished playing. If the file is not the same length as the Delay Size, it will still join delayed audio when the file finishes but will subtly speed up or slow down the output as needed to achieve the specified pre-set delay.

Alternate Build Mode 2 - PreRoll

In some instances, you may wish to build your delay without changing speed or playing an insert file. PreRoll Mode lets your talent start their introduction before the scheduled program time and is often used by studios feeding a network rather than a local transmitter.  

Set the Build Mode to "PreRoll" and press Build.  The talent should begin talking earlier than program air time, specifically by the same number of seconds as the Delay Size. This early start will be heard in the studio only.

For example, if you feed a network at 12:00 Noon and use a 10-second delay, you would back-time and start the PreRoll at 11:59:50, 10 seconds before Noon. PDM II begins delivering the delayed content at 12:00:00.

As soon as Build is pressed, the front panel LCD will begin to count up with numbers and a bar graph as shown below in Figure 4.  

While PDM II is counting, studio audio is being sent to the internal delay memory and output audio is muted. When the full delay time is reached and the solid bar fills the display, it will begin playing delayed audio to the air chain.

Cough Mode

Pressing and holding the blue Cough button stops audio from being routed to the delay memory, and the talent audio is heard in the control room only, not on-air. Audio already stored in the memory (prior to the Cough button being pressed) continues to the transmitter. As soon as the Cough button is released, PDM II immediately begins to rebuild the delay.

Exit Modes

When it is no longer necessary to delay program audio, PDM II can exit and return to real-time programming by Rolling Out or Compressing.

Exit by Roll Out

This is the traditional method of exiting delay, not dissimilar to the method used by old-fashioned tape delays.

• The talent finishes speaking then presses Exit.

• PDM II continues to play delayed audio at normal speed until the delay is empty, then passes the incoming audio through to the output with no delay.

Note: The COUGH button has no effect while exiting by roll out.

In this mode, nothing is recorded after the talent presses Exit. It’s as though the talent's mic automatically gets turned off during roll-out then turned back on when the delay reaches zero.  

Exit by Compress

This mode allows exiting delayed mode without the need for the talent to pause.

• The talent presses Exit and keeps talking.

• PDM II keeps recording audio into its memory.

• PDM II plays out everything in its memory at a slightly faster speed until it is empty and the output catches up with the input, at which point it drops into non-delay mode.

The time it takes to exit a delay using time compression depends on the size of the Delay and the Speed setting. As a general guide, choose a Speed appropriate for your talent’s style of delivery so that listeners won’t notice the time compression. Hosts who speak very quickly usually sound better with lower Speed settings.

Quick Exit with Compressed Roll Out

This mode is faster than using either the Compress or Roll Out modes by themselves. To use it, PDM II should be set to Compress mode.

• The talent presses Exit and stops talking.

• PDM II plays out the buffered audio from its memory at a slightly faster rate than normal.

• The producer listens to the output of the PDM II and presses Bypass after the talent's final word, then goes to the next program element.

Important: Because PDM II is still recording during a Compressed Roll Out, there is a possibility that anything the talent says after the segment is "over" may get passed to the transmitter and end up on air. Pressing Bypass instantly switches PDM's output to real-time and erases its memory, so pressing Bypass immediately after the talent's last word reaches the output.