How To Use A Three-Head Tape Deck As A Delay Unit With Your DAW

A three-head tape deck, or even a tape delay simulator pedal can be configured as a tape delay unit for use with your DAW, or used to give your digital tracks the sound of analog tape

By Phil O'Keefe

In a recent thread on the Harmony Central Effects forum, a member named "Loobs" was asking about the delay effects used on Jimi Hendrix recordings. While I do not know the specifics regarding the actual equipment they used for his classic albums, I mentioned that using studio tape decks (like the Otari MX5050 IIb pictured in Figure 1) for delays was a common practice during the 1950s and 1960s. This led to a request for details about how to set this up, which led me to write this article.

Fig. 1: An Otari MX5050 IIb 1/4" three-head reel to reel tape deck.

THE CONVERSATION

THE SETUP

You need a three-head (erase / record / playback) tape deck that can monitor off of the playback head in near-real time while recording. Most 3 head decks can do this, and even some cassette decks have 3 heads and the ability to monitor off the playback head. It's essential that the tape deck be configured to monitor off of the playback head while recording, and not from the recording head like you normally would when doing an overdub on an analog multitrack deck. This way, instead of the recording and playback signals being synchronized, the recorded signal is delayed; the incoming sound is recorded by the record head, and then several milliseconds later as the tape winds through the machine, the recently recorded tape will pass over the playback head (Figure 2), where the delayed signal is played back and routed back out to the mixing console or computer audio interface / DAW.

Fig. 2: A three head tape deck, showing the location of the three heads and the direction of the tape travel (click on images to enlarge).

Getting things set up is fairly simple. Route the mixing console's aux send into the tape machine input. Route the tape deck's output back into a second channel (return channel) on the mixing board. Turn up that aux send knob on any channel you want to route to the delay. If you're doing this with a DAW, you can assign a software aux bus to a hardware output of your audio interface, and route that to the tape deck's input; then send the tape deck's output into an input on your audio interface (Figure 3). The software routing on the virtual mixer would be set up exactly the same as on a physical mixing console--use an aux send to route the signal out of the audio interface and into the physical tape deck. Plug the tape deck's output into an input on the audio interface, and assign the "echo return" from the audio interface's input to an unused DAW track (or an aux input mixer channel) to return the delayed signal back to the DAW.

Fig. 3: Raise the aux send on the track you want to add delay to, and return and record the delayed signal to a new track. Since this interface only has two analog inputs and outputs, I'm patching interface output #1 to the delay unit, using a pre-fader aux send, and hard panning the return signal to the opposite side (output #2) and muting the source track to prevent unwanted feedback; if you have a multi-channel audio interface, you can assign the aux send and return to secondary outputs and inputs while leaving your main monitoring outputs unaffected.

Put the tape deck into record and roll tape. Hit play (or play and record, if you're re-recording the delayed signal) on the DAW. This basic setup will give you a single delay. Raise the level of the aux send on the RETURN channel (Figure 4) for feedback / regeneration / more "repeats". Be careful though: if you raise it too much, you'll get runaway regeneration and uncontrolled feedback.

Fig. 4: Raise the aux bus level on the return track for regeneration. Be careful--a little goes a long way!

THE DETAILS

The delay time will depend on two different factors:

First is the speed the tape machine is running at. If you have the machine running at 15 IPS (inches per second), the delay time will be exactly half of what it will be if you instead run the tape deck at 7.5 IPS. Slower tape speeds = longer delay times. You can use a VSO (variable speed oscillator - the tape deck's "varispeed" knob) to fine tune the speed of the tape deck, and thus the delay times. Most varispeeds give you a +/- 6 to 10\% adjustment range.

Second is the physical spacing between the record and play heads. If they are spaced further apart, the delay times will be longer for a given tape speed. In other words, if the heads are spaced 1.5" apart, the delay time will be twice as long than it would be if the heads are spaced .75" apart.

Here are some examples: At 15 IPS, a 1.5" head spacing gives you a 100ms delay time, and .75" spacing gives you a 50ms delay time. Drop the tape speed to 7.5 IPS, and the lengths of the delay times double: with a 1.5" tape head spacing, you get a 200ms delay, and with a .75" spacing, you get a 100ms delay time. You can get different delay times by increasing or decreasing the tape speeds. Common tape deck speeds are 1 7/8 IPS (cassette and some reel to reels), 3.75 IPS (some cassette decks and reel to reels), 7.5 IPS (fastest speed on most "consumer" model reel to reels), 15 IPS and 30 IPS - both of which are "pro machine" speeds.

When using a DAW's virtual mixer and audio interface, your delay times will be slightly different than if you're using an analog console for the sends / returns. This is due to the slight delays involved due to the A/D and D/A conversion stages, and will vary depending on the interface you're using and the buffer sizes you select on your computer. And of course, when re-recording the delayed signal back to the DAW, you can adjust the delay time after the fact by merely sliding or nudging the processed track to a new location relative to the original source track.

ALTERNATIVES TO TAPE

The simplest is to just use a plugin, but half the fun is in the experimentation, and in getting your own unique sounds. Here's an alternative approach: If you don't have a three head reel to reel deck, but want to experiment with "tape delays" with your DAW, you can utilize a tape delay simulator pedal, such as the Skreddy Echo (Figure 5) or Strymon El Capistan... even a "real" tape delay such as the Fulltone TTE or an old Echoplex or Roland Space Echo can be used instead of / in place of an analog three-head reel to reel. Just put it into the chain in the place of, and instead of the analog reel to reel; the setup is basically the same, but make sure you have the mix control on the delay unit set to 100\% "wet". Set the repeats to minimum if you want to simulate a tape deck, or adjust to taste for additional repeats and regeneration.

Fig. 5: A Skreddy Echo pedal is designed to simulate a classic tape delay, and can be used in place of a reel to reel deck. I've dialed in a bit of "warble" to better simulate the "wow and flutter" pitch fluctuations of an old analog tape deck.

If you route the delay return to a new track instead of an aux input (return) channel, you can record the results; this way, you can mix in the "delays" later by simply raising or lowering the level of the recorded track, without having to reconnect the aux send and return and the external delay device.

TAPE DECK (OR TAPE ECHO SIMULATOR) AS A TRACK SIGNAL PROCESSOR

One final nifty trick that I learned years ago from Harmony Central Editor-In-Chief Craig Anderton: This same configuration can be used to "analogize" your digital recordings. Set the external tape machine (or tape echo simulator pedal) up as outlined previously, and record the output of the tape deck to a new track in your DAW. You'll want to make sure you have it set up for only a single delay, with no repeats or regeneration set on the return channel's aux send, or on the pedal's controls. The track will be a reproduction of the original source track, but with the analog processing of the tape deck (or tape echo pedal) applied to it. The tape return channel will be delayed relative to the digital source track (Figure 6). Once you are satisfied with the sound, just nudge it over until they line back up, mute the digital track, and then use the "tape  effected" sound instead (Figure 7). Unlike when recording straight to analog tape, you can experiment with how hard you "hit" the tape deck (how loud the recording level is set, and how noisy, clean or distorted the resulting sound will be) and adjust the quality of the "tape sound" after the fact--after you've captured the performance safely to digital, and without wearing the musicians out with countless repeat performances while you experiment with different analog recording levels.

Fig. 6: The signal will be delayed relative to the source track. To find out how long the delay time is, drag your cursor from the beginning of the first note on the original track, to the same spot on the first note of the delayed track, and read the length of the delay time on your DAW software's display. Then you can nudge the track by the same amount to get them into exact alignment.

Fig. 7: When used as an analog-sound effect processor for your digital tracks, drag or nudge the delayed sound into alignment with the original source track, then mute the original track and use the replacement "analogized" recording in its place.

Using outboard equipment in this way isn't just a way to copy "old school" techniques--it's about getting distinctly unique sounds that help your music stand out from the crowd, so experiment and get creative with the sounds you use, and the ways you process them. Sometimes that means thinking outside of the box...

SAMPLES OF A DIFFERENT KIND

I've included a couple of audio examples so you can hear this technique in action. Rather than utilize my studio tape deck and multi-output Pro Tools HD setup, I used gear that you are more likely to have available--an Avid Mbox interface and a tape sim delay pedal (Figure 8). In the audio samples, the original mono drum machine loop is hard panned to the left, while the delayed signal that was processed by the Skreddy Echo pedal is hard panned to the right. This will allow you to use your DAW's balance controls, or better yet, to split the stereo tracks into two mono files in your DAW so you can listen to either signal independently, or together, in any ratio you desire. Turning the delay track up or down in volume relative to the source track is conceptually similar to raising or lowering the mix knob on a delay pedal--try it!

Fig. 8: The setup used for the MP3 examples--an Avid Mbox, and a Skreddy Echo, patched together and ready to go; with the software aux send routed out of the interface and into the delay, and the delay's output routed back into the interface and to a new track in Pro Tools.

In the first MP3, the signal is processed with no regeneration - the "repeats" knob on the delay unit is set to zero, and the aux send on the software mixer's return channel is also at zero (Figures 3 and 9). For the second MP3 example, I gradually raised and then lowered the aux send on the return channel while recording, which created more regeneration in the middle of the audio file (Figures 4 and 10).

Fig. 9: The audio track waveform display of the first MP3 file; no regeneration, just straight delays.

Fig. 10: Raising the return channel's aux send while recording results in regeneration, or "echoes of the echoes", which are clearly visible on the waveform display, and audible in the second MP3 file.