Bass Pod Pro XT – Analog vs Digital I/O

One question that came up as a result of the last post was this:  “Would the bass pod pro XT sound better if it was connected digitally?”  Today we’ll find out 😉  Oh, and for you guitar players out there, this probably applies to you if you’ve got any of the older guitar pod devices.

With that being said, let’s recap a little bit.  Last week’s experiment involved recording a bass guitar ‘direct’ through three different mechanisms.  The conclusion of that post (for me) was that the direct inject box offered the best sound, but it was very similar to running through the interface.  Of the three, the recording that fell short was that off the bass pod pro XT.  The recording seemed to lack some top end in general, it definitely seemed worth investigating.

And now for a little voodoo/science..

Now I do have a theory, but this is purely based on speculation at this point.  You ready?  Here goes..

I think that the Bass Pod Pro XT’s a/d and d/a converters are crap.

There I said it (I feel better, don’t you?).  But let’s think about this for a minute as this shouldn’t necessarily be good for any signal.  Each time we do conversion in either direction we lose something from the original signal.  This is because of the simple fact that a digital representation of a signal is nothing more than approximation.  If we keep approximating (you know, rounding off numbers here and there), and we’re going to get a signal that is not quite the same.  Simple as that.

Let’s take a look at how the converters work in this setup.  Say I run my bass pod in full ‘analog’ mode.  This means that my interface (the apollo) outputs a signal via patch cable to the pod.  Now the pod is digital on the inside, so it converts the signal to digital, does its processing, and then spits that signal out (via patch cable) to the apollo.  When that signal leaves the pod its D/a converted, and when it arrives at the apollo, you guessed it, its a/d converted again.  One other interesting thing to keep in mind, through this chain that would actually be the 4th time the signal has been converted – remember it was a/d converted by the apollo on the way in.

Now if we connect digitally to the pod we basically skip all 3 of those analog <-> digital conversions.  Seems like it should simply be better, and well yes it should although we probably shouldn’t be able to tell.  Keep in mind: if a device has quality converters in it, we’re pretty likely not to notice.  If we do notice, it shouldn’t be egregious or should only be detectable by those amazing folks on the mastering forum.  There are plenty of digital devices out there and lots of them sound just fine hooked up either way.  With that being said, I’ve got a little hope for the pod pro.  I mean, this thing is a bad ass professional device… isn’t it?

The experiment

I’ve taken our bass line from before (I’m using my favorite, the recording from the DI100) and run it through 3 presets in the Bass Pod Pro.  This isn’t so much about the color provided by the amp simulation as much as its us looking for interesting things happening when we route the audio differently.  Now for our experiment I’ve fiddled with things to get the levels as close as possible.  There’s also no processing on these recordings although we are doing a low cut at 40Hz.  Here are the results, note that I’m purposely letting the audio player hide which is analog and which is digital, but i’ll tell you below. A wise producer once said – use your ears, so consider this practice in doing so 😉

Adam and Eve

Adam and Eve – Analog
Adam and Even – Digital

The Fish
The Fish – Analog
The Fish – Digital

Love/Haight – Analog
Love/Haight – Digital

Conclusion — SPOILER ALERT!

To me there’s a pretty clear difference between the analog and the digital signals.  In all three cases I notice a lack of punch/growl/top end in the analog recordings.  The fish is the most obvious to me on this one (and i picked this preset because I had a hunch).  This preset is distorted and so it carries with it more high end than the other two tones.  In the analog case this preset just sounds lifeless and just plain bad.  The digital certainly presents everything this preset was meant to have.  Now if you haven’t guessed it yet, the top links are all analog, and the bottom are digital.  When it comes to the other two presets, they are fairly bottom end without much high frequency.  I can still tell the difference in the how the bass growls when it comes to the highs but there’s also something going on in the mids between the two that make the digital ones just cleaner.

With all that being said, sure, this device is fairly old.  You can get your hands on newer technology from Line 6 anywhere and its likely those converters are a lot better.  Depending on what you are looking for, you may be able to get along in analog land just fine.  When it comes to the studio, connect this device digitally if you can.  Digital isn’t always the easiest thing to work out, but this is highly dependent on your setup.  Luckily for me I don’t have much going on, but know what you are getting into (for starters, try reading up on jitter).

It certainly is a good sounding device and connecting it digitally definitely brings out the fullest the device can deliver.  One final thought: everything matters a lot more in the context of the mix – the quality produced by hooking up the pod the old fashioned way may not end up mattering that much when you get down to it.  Play with the device in your own studio and see what matters for you and your songs.  Alright, that’s it folks.  See you guys next time…

Further reading:  Analog to Digital Conversion