Flashback #9.2 Dump & Go – The Profanity Delay - Eventide Audio

Flashback #9.2 Dump & Go – The Profanity Delay

Flashback #9.1 covered, somewhat out of temporal order, the backstory of Eventide’s history in broadcast. This Flashback is about the Eventide product which became almost indispensable to talk radio and other stations whose personnel were benignly permitted access to microphones without considering the utterances of their late-night denizens.

A Feast of Memory

Eventide, as chronicled in our various flashbacks, feasted on memory. From the 1745 (shift registers) to the 1745A (good and slightly larger shift registers) to the 1745M and H910 (memory chips) to the H949 (bigger and better memory chips), each product generation used more and more memory. By 1977, we concluded that memory was—just barely—inexpensive enough to supplant the space, cost, and inconvenience of the dedicated tape recorders that protected the delicate ears and the even more delicate FCC license coveted by our candidate customers. But what about the BLEEP? Should we add a button to add this irritating, wasteful excrescence to the flow of programming? (Hint: I wouldn’t have written “irritating and wasteful” if there weren’t a better way.)

Yum! 16k chips, 10-wide by two chips high, this BD955 board boasted two rows of 1977 state-of-the-art memory chips, already twice as many as were in the 1745M delay line or the H949 Harmonizer®.

Even so, you’d have to have a fast trigger finger to bleep your obscenity in the 800 milliseconds of delay this board provided. With an array of eight boards, however, 800*8 milliseconds (6.4 seconds) could be achieved, long enough to catch a string of four-letter words and even a brief slander.

Today, a chip the size of a thumbnail can hold the equivalent amount of data to about a half-million of these boards.

What a Stupid Way to Make a Living

The actual purpose of the BLEEP (or brief jingle) that a station would play to eliminate the naughty utterance was to wait for seven seconds to pass while the delay tape wended its way through the second machine. But if the delay was done digitally, it could disappear in the same address-manipulation computations that the Harmonizer units could use to change pitch. No explosive charge necessary to move the tape heads instantly next to each other. Adding a DUMP button accomplished this as fast as a producer’s finger could move! And so, our BD955 digital delay line was introduced to immediate acclaim in the world of talk radio.

Extra credit for guessing how the product got its name and number (see Flashback #9.1 for clues). Did BD stand for Broadcast Delay? Yes and no.

And no credit for guessing the magic feature, since it’s described immediately below, that was responsible for a great increment of sales and even a patent action which we would have won had the infringer bothered to go to court.

Catch Up!

The one problem that still needed to be solved was: What to do after the DUMP? As irritating as the BLEEP was, the program could continue afterward. Nobody was fooled, but after being discommoded, the host could continue with a different caller, delay still at seven seconds. DUMPing the profanity left the program flow intact but the station without protection. The problem was how to get the delay back without listeners noticing. The solution turned out to be the pause that increments. 

Since the now-profanity-free programs were almost always people talking, we took advantage of the fact that (most!) people have natural pauses in their speech. Between words, sentences, speakers, one could always find a time period of a few milliseconds when there was nothing being said. It could be detected electronically and, again using address computation arithmetic, lengthened. As the announcers chatted, the time delay, zero after the DUMP, would build up second by second until the station was protected again. Seeming magic. And great sales.

A sidelight or so: As with most electronic voice manipulation, you can have some fun with it. Although the BD955 didn’t change the pitch of the announcer’s voice, it did increase the length of pauses. With reasonable control settings, this was barely noticeable—he just seemed to be talking a bit slower. With aggressive control settings, he might sound drunk. Or, using the pre-emptive oscillator setting, drunk and underwater! These controls were necessary because a handful of announcers had voices without pauses. The late Allison Steele, who styled herself “The Night Bird,” was in that category; we used her broadcasts to calibrate the product.

The follow-up model, the BD980, was designed by Jeff Sasmor and added intelligence by virtue of the newfangled DSP chips from Texas Instruments — the same chips that would become the engines that ran the H3000 Harmonizer.

We checked in with Jeff Sasmor for his recollections:  

The BD980 was the last design that I did for Eventide, and the second version of the Broadcast Delay, circa 1986. When I was asked to write about it, I was frankly a bit flummoxed because it was so long ago. But being a digital packrat, I found the original source code inside a zip file that was itself inside a zip file inside an archive in a dark corner of an SSD. This was all hand-coded in assembly language.

The original BD955 sometimes performed catch-up by increasing the delay periodically, causing audible artifacts. The BD980 used autocorrelation to allow the delay to be increased at times when no artifacts would be heard, or be at worst much less audible. This concept was derived from the H949 Harmonizer’s operation, with an interesting twist.

The basic way that BDs work is to gradually increase the delay back to maximum after the Dump button is pressed. The BD980’s catch-up algorithm took advantage of the unit’s large DRAM memory to “look-ahead” into sections of the audio memory that would be output much later in time. This increased accuracy when looking for the optimal times to increase the delay, ensuring the fewest audible artifacts.

This would have been nearly impossible to do at the time without the new technology of Digital Signal Processing chips (DSPs). We used a pair of Texas Instruments TMS32010s (as did the H3000 just a few years later!), which had a blisteringly-fast clock rate of 20 MHza speed which sounds almost silly nowadays but in those ancient times was quite respectable. 

One TMS32010 was used to control the front panel, the relays and other circuitry on the audio I/O board, as well as the actual operation of the four normal operating modes of the unit and the autocorrelation software. The other TMS32010 controlled the audio DRAM memory addressing as well as the handling of the data I/O from the audio in/out board.

As you can see, it had an adjustable “CATCHUP RATE” control:”

Thanks, once again, Jeff!


What a stupid way to make a living! The megabucks of our products, radio and television station fines, and regulatory indigestion caused by profanity, and, hopefully, its deletion. Wow. Just Wow.

Yet, nice living it was and to a large extent remains thus.

A Call for Precision!

There was one other Eventide product designed exclusively for broadcasters. As with the Monstermat, its applications were somewhat esoteric. Remember AM stereo? No, neither does anyone else. In fact, very few remember AM at all. AM stands for Amplitude Modulation or as the wags would have it, Ancient Modulation. FM, or Frequency Modulation, has major advantages in terms of listening quality, the most important of which is its relative immunity to noise and interference. AM is in a parlous state now, with many mom-and-pop stations eking out a precarious existence. FM is doing much better—possibly even good enough. For AM stations to compete with FM, they needed a system to improve the quality of their sound.

One scheme for rescuing AM was proposed, and it involved a digital delay that required more precision than just a specific number of milliseconds. AM coverage could be improved by adding transmitters! If you’re near enough to just one it will overpower the added one. But what if you’re in-between, and both signals are similar in strength? If you know where that area is, you can adjust the audio timing with a precision delay so that there is little or no difference in timing of the two signals, and therefore no flanging effects when receiving them both. (Another requirement is for precisely synchronized “carrier” frequencies so there is no “beat note” or a slow amplitude drift as the signals add and subtract from each other.)

Meanwhile, FM was going digital. To avoid obsoleting the hundreds of millions of radio receivers in cars, on tabletops, and in beach-goers pockets, one couldn’t simply discontinue the regular FM transmissions. Rather, using the wider bandwidth of each FM channel, digital signals were snuck in so that a special receiver could interpret them as well. But the digital signal took time to process, and there were occasions when the listener’s receiver would have to decide whether it or the analog signal would provide a better experience. If it switched from one to the other, or “blended” the two, the time difference in the audio could be several seconds, which would make it impossibly distracting. By delaying the transmitted audio to match the digital time-delayed audio, the switching or blending could be seamless. Again, the delay amount had to be precise to avoid echo or flanging effects.

How precise? Unlike our standard delay products, which could be varied by individual sample intervals of about 20 microseconds, the PD860 could be switched in one-microsecond increments. The specification read, “The PD860 precision delay features stereo; 20kHz frequency response; delay adjustable from 15 milliseconds to 5.24438 seconds; adjustable in microsecond increments.”

Is That All for Broadcast?

Although the Monstermat and its non-existent friends, the instant playback unit, and card-reader DJ enhancer, were included as part of our portfolio of broadcast products, the BD955 was the first in a long line of profanity delays. And, while our BDs have long served to protect the listening public from the scourge of profanity, Eventide’s Harmonizer effects units found their way into broadcast production. Broadcasters also used the H949 along with tape-speed controllers to compress the length of programs to fit in more commercials.

Profanity Delay Today

Our latest, greatest, Profanity Delay, the Model BD600, builds on decades of experience to fit perfectly into a broadcaster workflow.

Check out our previous flashbacks!