The Sum of All Parts Equals…What?

There’s a lot of talk these days about audio summing amplifiers. Several companies are making them and for the most part they are being presented as a go between for engineers that want the sound of an analog console without the cost and/or maintenance of the real deal. With most people mixing in or from Pro Tools these days, whose mixer has a qualified 144dB of dynamic range, the question arises of why you want to do this? The answer: coloration and distortion. On the surface that statement sounds a lot worse than it is, but the reality is that transformers or tubes introduce distortion, which in turn deliver that warm and fuzzy coloration that sum (get it?) of us love and some of us can live without. Aside from coloration of sound, splitting out tracks or stems from your DAW to one of these 16 channel boxes (most of them available are only 16 channels) has some other benefits as well. These include but are not limited to inserting analog gear across certain parts or stems of a mix and more defined separation of parts in the stereo field.

Over the past several years I have had the opportunity to test drive just about every summing amplifier on the market. Some of them have been very impressive while others have not. When I first started doing this, the biggest challenge I ran into was how to effectively do an A/B comparison between some of these boxes. If you think about it, it’s almost like trying to compare a mix done on an SSL console to the same mix being done on a Neve. It’s not really possible-they’re never going to be the same. Different mix decisions are going to be made on different boards. You could certainly put the time in and match the vibe, but to do a true A/B comparison is not technically possible. So, the idea of taking a completed multitrack mix from Pro Tools and stemming it out across a summing amplifier is not going to work. It’s going to change the sound, levels, coloration and so on. If you’re mixing in Pro Tools, there is no coloration. If you take said mix and run it through anything that has, oh let’s say a “dark” sounding transformer, your mix has just become very dull from a sonic perspective. Okay-so what if we run a finished two mix through the box just to compare the color? We could do that and it would be very telling-but, it would not show us how the box handles separation of different elements in the stereo field. Interesting dilemma, isn’t it?

So here’s what I came up with: What if we take a rough mix of a song with no automation, no EQ, no compression, no FX, etc. (just the raw tracks) and did some comparisons with those? We know what the raw tracks sound like, so if we just get some decent levels and print a couple mixes for comparison, that should give us an idea of what a particular summing amp is doing, right? Let’s see..

Below are three download links for a section of a blues song (Right-Click and choose¬†“Save Target As…”¬†to download). They are as follows:

1. A rough mix “bounced to disk” in Pro Tools HD

2. The same rough mix that has been outputted through the Digidesign 192 analog outputs and printed back into a stereo audio track (again through the analog inputs) in Pro Tools and

3. Again the same rough mix split out from the Digidesign 192 analog I/O and through the Tube Tech SSA2B Summing Amplifier and printed back into a stereo audio track (yet again through the analog inputs) in Pro Tools.

The split out was as follows: Drums (L&R 1/2), Bass Guitar (L&R, 3/4), Guitars (L&R, 5/6), Organ (L&R, 7/8), Horns (L&R, 9/10) and Vocal (L&R, 11/12).

Enjoy! I am personally very fond of the what the Tube Tech delivers and think you too will be presently surprised.