1 Topic by breslin (edited by breslin 2011-10-27 16:35:12)

  • Registered: 2011-10-23
  • Posts: 6

Topic: outboard processing (send/return loopback) with the ADI-2

It is possible to use an ADI-2 to send previously-recorded stereo audio through outboard gear, and then receive it back in so you can record the result. To do this, simply route your ADI-2's D/A outs to the inputs of your outboard gear, then send the processed signal into your ADI-2's A/D ins.

However, the ADI-2 does not allow monitoring of the processed signal. Its monitors are the same as its D/A output (and that's true for the front-panel headphone monitor too), so you can only monitor the signal that is being sent to your outboard gear, not the signal that is being returned.

A common setup for home recording studios is an HDSP 9632 plus the ADI-2, and you can indeed use the headphone monitor from the HDSP analog breakout cable, to monitor the outboard loop post-effect.

Setting up the cables is easy, but unless you're already experienced at using TotalMix, it can be a little confusing. Here's how to set this up:

1. Set up your headphones: find the pair of faders for the headphone signal coming directly from your sound card, in the bottom row of TotalMix. Set them to some safely low volume, like -24. Then while they're highlighted, find the pair of faders that are normally associated with the Analog Hardware Input from the ADI-2, in the top row of TotalMix. Make sure they're panned left and right, and set at 0.0.

2. Set up your send: find the pair of faders for playback over the ADI-2 (in the bottom row of TotalMix), and set them to 0.0. Then, while those faders are still highlighted, find the software playback channel you'll use to play back the pre-recorded audio, in the middle row of TotalMix. Set those faders to 0.0, and make sure all other faders are down. (You probably already have this set, because you normally monitor playback over your ADI-2.)

3. Set up your return: pick a free stereo channel in the bottom row of TotalMix, and raise its faders to 0.0. Also, control-left-click on the channel name (for both of the stereo channels), so it turns red. Then find the microphone inputs on the top row of TotalMix, and set their faders to 0.0, while making sure they are panned left and right. Also, make sure all other faders are down.

Finally: this isn't strictly necessary, but if you want to maintain the same line level, set the ADI-2 front-panel INPUT the same as the OUTPUT. I've noticed that there's a couple decibel loss even so. If someone knows why, please let me know. :)

That's it! You should be set up to monitor the signal returning from your outboard gear, as you send a stereo signal out of your ADI-2, through your outboard gear, and back into your ADI-2. Set up your DAW to play back the audio over the normal playback channel, and record the signal coming from the new channel you set up in Step #3 (the one with the names in red).

Once you've set this up, you probably want to save your settings. In TotalMix, click on the "Save" button under PRESETS, then click any of the preset numbers to save your settings.

  • Registered: 2011-10-23
  • Posts: 6

Re: outboard processing (send/return loopback) with the ADI-2

If you are limited to the ADI-2, and cannot or do not wish to use the headphones on your sound card, then you can still set up a loop the same way, but you cannot monitor the stereo signal on its way back into the ADI-2. However, you can do a couple unusual things to monitor a MONO signal on its return from outboard processing. Of course, if you need to process a stereo signal, you can handle each channel separately; you just can't handle both channels of the stereo signal at the same time.

To do this, reconceptualize the ADI-2 as providing completely separate dual mono, rather than stereo. This is not how TotalMix thinks of things, so again the following technique is a bit unusual.

For the sake of this explanation, we'll be playing back the pre-recorded program material through the ADI-2's right output channel, which will then be sent to the outboard gear. The outboard gear will process the signal, and then return it through the ADI-2's left input channel, which we will record. (You could reverse left and right if you want of course.)

So, setting up the cables to and from the ADI-2:

1. Right Analog Out goes to your outboard gear.

2. The return from your outboard gear plugs into Left Analog In.

3. For reasons that will become clear in a moment, plug your headphones into Left Analog Out.

Now the TotalMix settings:

1. Find the fader that is normally associated with the Left Analog Hardware Input from the ADI-2. (As you know, Hardware Input is the top row of TotalMix.) Set that fader to 0.0. Make sure that the panning on this channel is all the way left. You can mute the Right Analog Hardware channel or simply ignore it.

Explanation: The Left Analog Hardware Input is where the signal will flow through, after it returns from your outboard gear into the ADI-2. In fact, the signal will reach your DAW regardless of the Hardware Input fader, but you should raise this fader so the processed signal will cascade through TotalMix and reach Hardware Out, where you can monitor the processed signal with your headphones. (You can mute the fader for the Hardware Input that is associated with the ADI-2's Right Analog Input; you're not going to use that channel.)

2. Set Software Playback (that is, the middle row of TotalMix) to 0.0, on the Right channel. Then, definitely be sure to mute the Left channel.

Explanation: Software Playback on the Right channel governs the level that is being handled through TotalMix and sent over to your outboard equipment, when you play back your pre-recorded program material. You want to mute the Left channel, since you must not use that channel for playback. If you accidentally play back on the left channel, the signal coming from your outboard gear (through the left hardware input) will will be mixed with the original material that you're playing back (on the left software channel). (Plus there's some small amount of latency involved in this technique, so if you actually do want to mix original and processed material, it's still better to do this later.)

3. Set Hardware Output (that is, the bottom row of TotalMix) to 0.0 for the Right channel, and something conservative and quiet like -24 on the Left channel.

Explanation: The Right channel governs the level that is being sent through Right Analog Out into your outboard gear. The Left channel governs the level of the processed signal after it has returned from your outboard gear, on its way to your headphones. During playback and processing, move this Left channel fader to adjust headphone volume.

Again, it isn't strictly necessary, but if you want to maintain the same line level, set the ADI-2 front-panel INPUT the same as the OUTPUT. I've noticed that there's a couple decibel loss even so. If someone knows why, please let me know. smile

Ok, now you should be all set. Set up your DAW to play the source material over the Right channel, and record the Left channel.

Because you took the unusual step of plugging your headphones into the Left Analog Output (on the back of the box), you can monitor the effect loop (and adjust the effects as desired, in real time). Again, use the Left Hardware Output fader to adjust the headphone volume.

To attenuate the signal going into your outboard equipment, you can adjust the Right Hardware Output fader.