Help with phase issues (Focusrite Saffire 40, Shure SM57)

7

7enderbender

New member
Hello Everyone,

I'm using the time off from work and the holiday weekends to work on some new material for my band projects. Setup is a Mac with a Focusrite Saffire 40 interface, my guitar rack centered around a Mesa Boogie Triaxis (running with a tube stereo power amp, which is why I mention this), two cabs right now (a stock Marshall 4x12 and a Mesa 2x12). I use the rig live (with either the two cabs or the 2x12 set up in stereo) and have never noticed any phase issues.

When recurring tracks today coming from the two cabs I noticed they were canceling each other out in Logic Pro X. I use two SM57 mice (one old one new) and two identical Live Wire cables,

So my first though was that I messed up when rewiring the Mesa cab to stereo (with a original Mesa jack plate and following their instructions). Or that the Mesa and Marshall cabs don't get along in that respect. Well, I tested it by moving the microphones together on one speaker cone and they still phased out. So with that I'm ruling out issues with the cabs. I am able to phase correct one track ion Logic - but I still find it odd.

What is the source of the phase inversion? The Focusrite doesn't have phase switches, I'm using the two front mic inputs (1 and 2, both set to mono). Could it be that the Saffire itself isn't wired correctly? Could the two versions of the SM57 be different? Cables seem unlikely. So I'm at a loss.

Again, this is not an issue now for recording now that I know - but I'm concerned I may end up in the same situation live with my rig and using the same microphones and cables. What are the correct ways to troubleshoot?

Thanks
 
What is creating the stereo image? If it is some sort of stereo chorus, most of those are stereo because they are 180 degrees out of phase...
 
Farview said:
What is creating the stereo image? If it is some sort of stereo chorus, most of those are stereo because they are 180 degrees out of phase...
Click to expand...
That's a pretty broad statement, and not even necessarily true. A lot of stereo choruses are actual just dry on one side and vibrato on the other. Those that are chorus (dry plus vibrato) on both sides usually invert the vibrato on one side, but the dry usually isn't. Summing those will cancel the chorus effect, but leave with the dry signal.

Anyway, none of that explains why two mics on the same speaker end up canceling. My bet would be the mic itself. The cables are easy to test if you've got a meter. Testing the mic is a bit more complicated, but not that difficult.
 
ashcat_lt said:
Anyway, none of that explains why two mics on the same speaker end up canceling. My bet would be the mic itself. The cables are easy to test if you've got a meter. Testing the mic is a bit more complicated, but not that difficult.
Click to expand...

So I've done some testing and digging since. You are likely right in that it is one of the microphones. For clarification: all (stereo) effects are turned off for recording so it's not that. And you are right in that my initial concern that it might be a problem with one or more of the speakers wouldn't explain why it does it on the same speaker - and actually vocals also as i've since learned. I swapped the older SM57 for a SM58 and the issue is gone. In fact, the old 57 doesn't sound right by itself either. So it was probably damaged. Looking into if this might have been a fake all along which is odd given that it is from the early 90s or even older and there was no ebay then where people bought $20 mics in bulk form China. My other thought is that it might have been swapped at a gig over the years at some point. Be that as it may. I'm off to look for microphone rebates at my local GC...
 
Could you please define "doesn't sound right" ? Depending on the age of the older 57 it would be no surprise that it produces a different "sound" mainly because the output x formers in the newer models are not as good. There is actually a mod for a new version of the 57 that actually removes the xformer altogether.
 
Last edited:
Thanks everyone for weighing in. Here's the update: I'm 99% sure the issue was indeed caused by the older SM57 (late 80s/early 90s, came used from a production company a quite a while ago). More research and testing showed that it was wired in reverse (green and yellow wire switched) - so it was likely set up as a designated under-snare mic or maybe just a mistake. Even then it didn't sound like the newer one - in my opinion worse and lacking low end. I have yet to try that a bit more - especially since I'm using the mics right now on two different types of speakers (G12T-75 and V30). I don't like the results with the V30 - which generally is no surprise since I'm one of the weird people who just like the G12T75 over most other speakers - but I still decided to buy another new 57 yesterday to rule out this being a mic issue (either due to damage or just because I'm again weird and prefer new 57s over "vintage" ones...

The good thing is that I learned something. Thanks for everyone's help here again.
 
I am also one of those people that like the 75'same over the V30's.

My cabinet is filled with tow g12t75's and two 80's. It is the best sounding cabinet I've ever heard, in my opinion.
 
Farview said:
I am also one of those people that like the 75'same over the V30's.

My cabinet is filled with tow g12t75's and two 80's. It is the best sounding cabinet I've ever heard, in my opinion.
Click to expand...

I don't think I know the 80s. I have a pair of 100s in a Fender combo amp which sound nice too. After recording some more tracks yesterday with the new 57 on the V30 there was definitely an improvement (same mic position etc) on the low end. Right now I'm tracking the V30 together with the 75 from my Marshall cab. They mix well together and I've heard a lot of people do it this way. I'm actually tempted to get another Mesa cab for live use and mix 30s and 75s with one each in two 2x12 cabs.
 
7enderbender said:
I'm one of the weird people who just like the G12T75 over most other speakers .
Click to expand...

That's not that weird. Most people don't even know what speakers are in their cabs.

I think G12T-75s are real good "live" speakers. I don't think they record as well as a Vintage 30.

One of my Marshall cabs has some mid-80s G12T-75s and 1981 G12-65s in an X-pattern. That is a killer sounding cab.
 
You must log in or register to reply here.
Back
Top