D.I.Y.: D.V.S.F. w/ D.N.F. (i.e. ADT!)


8 posts

Last post 23/07/2017

      Original post

      ...Do wot?

      'Tis an accidental discovery, which I will simply attempt to describe here. Please, do try this at home:

      ADT means Artificial Double Tracking, of which more later. It used two tape machines to create a delayed signal, which was fed back to the input, then recorded on a third machine. This gave The Beatles an entirely new sound, which was first heard on the "Paperback Writer/Rain" single, and later on Revolver. It also allowed them to spend much less time double-tracking their vocals, which they were fed up with by the spring of 1966.

      Here, then, is the recipe for DDT (Digital Double Tracking...)


      1) An input source--which could be anything under the sun with a line-level output.

      2) A Xitel InPort A/D converter (or similar), as used for transferring audio via the USB jack on a computer.

      3) 1 Computer with the InPort recording software running. In my case it was called LP Recorder, a simple two-track, no-frills setup.

      4) A second computer or other recording device. This will be your destination device, similar to the third tape machine as used at Abbey Road.

      First, plug the headphones into the recording device (4), then plug the output of the computer (3) into the input of (4). Your input source, which was a tape deck in my case, but could also be a mixing console or similar, should now be plugged into the InPort. Start the input source (1) and observe the levels on the A/D converter software. Unlike analog recording, you are advised to keep the signal out of the red as much as possible.

      Mix well...

      Next, right-click on the speaker icon, in the lower left-hand corner of your computer screen. Select "Open Volume Mixer."
      You should be hearing the delayed input source, as you do this. The headphones must be plugged in AFTER the computer (3), or you will not be able to hear the delayed signal. The InPort device provides a delayed signal, which is controlled by the FM fader on the virtual mixer you just opened, in addition to the input signal. By moving the LINE fader you should be able to hear the original, real-time signal. You can now mix the delayed signal and the original signal.

      Stir until done.

      The delay is usually 1-4 seconds, which I believe can be controlled by altering the cache memory file size. I never bothered to try, though--I was just so stunned that I had got this sound at all that I filed it away in my memory banks until now.

      You may also find, that by using the microphone input, you have a third option for feeding sounds into the delay loop, but this will likely not be a delayed signal unless you change the software settings to recognize it.

      Season to taste.

      This gives a sound similar to ADT, but with two important differences: ADT used tape machines and a vari-speed, which meant that the pitch of the source signal would be lowered as well as delayed. They had more control over the delay time than this method provides, as described here. Of course, the use of pitch control add-ons and possibly even external delay processors could allow you to get a sound much closer to the one they got at Abbey Road...

      As for the aforementioned alphabet soup:
      "In photography, [placing] a negative directly over another does not alter the image [unless] it is moved slightly. ADT does this with tape."
      "...they often liked to double-track their vocals, but it's quite a laborious process and they soon got fed up with it. After a [difficult] night-time session doing just that, I was driving home and suddenly I had an idea..." --Ken Townsend

      DDT does this without tape, using the original analog signal, and the digital signal into which it is converted. This process takes not a few clock cycles to be processed, so the end result is a delayed signal, which can simply be added back to the input signal, then recorded. By default, only the delayed signal is heard. But by using the expanded mixer, you now have enough control over both signals to combine them, and make them sound similar to ADT.

      "John Lennon was the prime motivation [for the invention of ADT]...But he was no technical genius and [asked just once] how it worked. "I knew he'd never understand it," said George Martin, "so I said, 'Now, listen, it's very simple. We take the original image and we split it through a double vibrocated sploshing flange with double negative feedback.' He said, ['Pull the other one!'] I said, 'Well, let's flange it again and see.' From that moment on, whenever he wanted ADT he would ask for his voice to be 'flanged' or call out for 'Ken's flanger.' "

      -- The Beatles Recording Sessions, p.70 (6 April 1966)

      You may also wish to call the DDT version a PHLANGER...now that I think about it... :

        ^^ As I have recently been thinking of John's double tracking voice
        on his songs. Love the dreamy Quality it produces.
        Thank you for the technical explaination.ð???ð?¼

          What is the difference between this and REVERB that was made popular in the 60's? It was also a time delay effect that produced the echo like sound?

            Frankly, not much.

            As described, it's simply an echo-type effect, i.e. a long delay of 2-4 seconds. I believe more could be done with it, to bring it up to the ADT standard. Also, this technique is similar to ADT in the sense of being a feedback loop, as opposed to simply adding reverb, which would not allow you to control pitch or duration. Also the sound is quite different from adding reverb since you would still be working with one original image in that case. Here you have enough time to alter the sound before you feed it back in, possibly by using the MIC input to the mixer, and of course, matching levels! This is an idea I would have done more with, but it's nearly 7 years on and I haven't...so it's time to open-source it.

            With reverb, you hear mostly the decay of the sound, but in this case you are hearing the entire sound fed back on itself. If you've ever used an Echoplex, that was a miniaturized version of ADT, but it used a loop of tape and worked by physically moving the playback head away from, or closer to the record head. ADT used three washing machine-sized tape recorders, and could only be applied during the mixdown phase of the process. I suppose it would be a bit more accurate to think of it as a digital version of tape echo, the kind John Lennon was known to favor. When I first heard it I was gobsmacked--I immediately thought of ADT and the sounds on Revolver.

            Since you have two, full images, they are identical, so you don't hear the clams and other slight imperfections (such as: "You say you want a revo-JOOSH!-ion...") made when frustrated, tired singers do take after take trying to match two performances as closely as possible.

            More on the technical details of the original invention:

            "...ADT is a process whereby a...signal is taken from the playback head of a tape machine, is recorded onto a [second] machine which has a [vari-speed], then fed back into the first machine to be combined with the original signal.

            As for "Tomorrow Never Knows," 87 seconds into the song, Lennon's voice is first heard routed through a Leslie speaker. Before that, ADT is the effect we hear. John had requested: "I want to sound as though I'm the Dalai Lama singing from the highest mountain top. And yet I still want to hear the words..."

              Thanks! Great Stuff! My grandson is starting his second year
              of college studying the recording aspect. I will pass this info on.

                Here is a funny/ sweet video of John Lennon. In the beginning he talks about living double tracking.

                British Humour!?

                Woman (rare):


                  Thank you for the kind words...the "Woman" track is very revealing, not only of John's humour, but of how the track evolved into the final version. I do hope this technique proves useful. I hope also that some of you will post the results you obtain here, as I would be very interested to hear them.

                    OR...one could simply purchase this:



                    "Well, I've sung it once lads, just track it for me." -- John