Pedal order does matter, but cool things can happen when you buck the norm.
The general approach with delay or echo effects is to place them after distortion or gain devices. If your amp is a multiple-channel modern affair with preamp and master volume controls, odds are it has an effects loop as well. Effects loops were purposely created to place time-based effects like delay in them. This is because time-based effects can sound out of control and muddy when run before distortion. So, much of the time, delay in the loop is the way to go.
Except when it isn't the way to go. A little out-of-control and a bit of mud in your tone is sometimes just what the doctor ordered. Many classic recordings by revered guitarists were made while running echo or delay into a distorted amp—with legendary results.
Eddie Van Halen. Eddie's early sound was achieved by cranking every knob on his late-'60s Marshall Super Lead to 10. It goes without saying that there was a hefty amount of distortion, but Eddie successfully ran an Echoplex EP-3 into the front end of his amp that significantly enhanced his tone and the guitar parts he played. For the longest time, I couldn't quite understand how he played the parts on “Ain't Talkin' 'Bout Love."
The main arpeggiated-chord sequence sounded pretty close when I played it, but it wasn't quite the same. And when I tried to mimic the syncopated skip in the chorus' Am to G chord change with my right hand, it just didn't sound correct. Once I realized there was a 300 ms echo with one repeat slapping back throughout the entire song, however, everything came into focus!
Similarly, there's a clearly audible echo bouncing back on the main rhythm riff in the chorus of “On Fire." The echo is very dynamic because it's running into a distorted amp and it gets louder or softer depending on how hard the guitar strings are attacked—part of the fun and magic when running an echo this way.
Joe Walsh. Another great example can be heard in the James Gang's “The Bomber" from 1970. In it, Joe Walsh douses his guitar solos with a healthy dose of long tape-echo via an Echoplex set with plenty of regeneration (feedback).
This is way before effects loops, so running a delay into the front of an amp was really the only way to go, and it's obvious that the substantial echo at least partially dictated the way the solos unfold. Along with fuzzes, wahs, phasers, etc., readily available echo devices were new and exciting in 1970. Guitarists like Joe embraced the technology and it's fascinating to listen to how the gear influenced the creative process.
Making It Work. There are a few loose guidelines to follow when running echo into a distorted amp or overdrive/distortion pedal. First: The tone of the echo repeats is crucial. Tape delays and analog echo units have limited fidelity and tend to roll off the top end. This treble roll-off becomes more pronounced with each repeat and the attack is also softened with each subsequent repeat. All of this helps the delay blend in with the guitar's core tone. If the delay is too clean and bright, it can tend to obscure and cloud the dry tone, and the result is often unpleasant. If you don't have a real-deal tape echo or an analog delay, try a digital unit with simulated analog or tape settings like the Boss DD-7 or Line 6 Echo Park. Or try a digital unit like the Boss Space Echo, Strymon El Capistan, or MXR Echoplex that is specifically meant to replicate a tape delay.
Make sure you start with the mix and feedback controls set low. The mix control is critical here, and you'll usually want to keep it just above its minimum setting. Keep in mind that if you make changes to your amp settings that result in more or less overdrive, you'll have to adjust the echo's mix control to compensate.
Creativity Is Key. In my opinion, the coolest thing that can result from running echo into a dirty signal is that it might affect the way you play and write. Just like Joe Walsh, Edward Van Halen, and many others, you might create parts, songs, and solos that wouldn't have been the same sans echo or with echo run in the cleaner fashion (post distortion). Don't ever be afraid to try patching your effects in an unconventional way. You might just stumble onto something epic.
Until next month, I wish you good tone!