I recorded an album on an Akai DPS16 a few years ago and was relatively happy with the results I got. After that, I had the use of an analogue mixer and some ADAT recorders and decided to use this setup to record the next batch of songs. When I went to mix them, I obviously didn't have the same automation that I had with the DPS16 and got frustrated when I couldn't save a mix and then go back to it and change it if needed. I left the recordings for a year or so.
Recently, I decided to transfer the audio on to the DPS16, by connecting the -10dBV jack outputs on the back of the ADAT machines to the DPS16. I then mixed the song in the DPS, using the built-in effects, and the automation and session-saving features. The results seem to sound better than my mixes when I just used the DPS for recording and mixing. Have I just got better at mixing? Or does it have something to do with the equipment I used?
Does it matter that the DPS16 operates at -10dBV, which is classed as semi-professional, whereas the analogue mixer and ADATs operate at professional +4dBu levels? And would the 48kHz sample rate of the ADAT machine versus the DPS16's 44.1kHz make any difference? Lastly, would I get even better results by transferring the tracks from the ADATs to a PC?
Fintan Donnelly
The 16-track Akai DPS16 hard disk recorder (reviewed in SOS September 2000) has a number of features that come in handy when mixing. For example, you can take snapshots of a mix, so you can revisit a project at a later date. This allows you to rest your ears, take a break, and listen again with a fresh mind — and invariably get a better result.
The unbalanced outputs on the rear panel of the Alesis ADAT XT are no less capable of providing decent-sounding signals than the balanced ones, providing the connected equipment is configured to the same standard. Technical Editor Hugh Robjohns replies: Lots of interesting questions there, Fintan. To answer the first, first: you may well have improved your mixing skills over time, but I also think your way of working with the DPS makes a big difference. Being able to create a mix and then come back to it and make tweaks after a break (even if only an hour, to let your ears and musical memory recover) usually produces better results, in my opinion. And that is obviously easier on a system with some kind of automation than one without. I'd certainly be lost without moving faders and automation these days!
Next question: operating levels. There are two common music recording standards, +4dBu and -10dBV, as you say, with the former being more associated with professional equipment and the latter with semi-pro and domestic equipment. But these are just electrical interface standards. They don't have much impact on the audio signal quality per se and, as long as you match levels appropriately when connecting equipment, all is well. There is no reason why you can't create totally professional results on a device that happens to have a nominal -10dBV interface level! Likewise the sample-rate issue. There is a completely negligible audible difference between the 44.1kHz and 48kHz rates, and if your end product is destined for a CD, it makes sense to stick with 44.1kHz. There are some technical advantages to working at one of the higher sample rates (88.2kHz or 96kHz) if your system supports it and can still provide the necessary processing power, but if your choices are only 44.1 and 48, then you should use 44.1kHz.
If the option exists to increase the word length beyond 16 bits (and there's a 24-bit option on your DPS16, I believe), I would recommend you use that. Essentially, working with a longer word length lowers the noise floor and provides greater headroom, both of which make recording and post-production easier. You'll have to reduce the word length back down to 16 bits for the final CD version of your track, but that's a small inconvenience compared to the large technical benefit.
To answer your final question, there may be an advantage to taking your ADAT tracks and mixing them in a computer, in that you'd have all the same kind of mixing automation functions of the DPS16, with far more facilities thrown in on top. But the specifics depend on which DAW package you are using, which hardware control interface you have, and so on. The majority of people do work with computers these days, but there is quite a learning curve to climb with some of these platforms.