Members Deeprig9 Posted June 19, 2008 Members Share Posted June 19, 2008 Last night I politely asked the sound guy to mic both my speakers, he was reluctant, said he has the same amp and only ever mics one speaker, but it was no big deal, he'd mic them both. He did. We soundchecked. Everything cool. After the show, breaking down, he said "Hey man, there was a problem, the two mics were phasing each other out, I didn't realize it until halfway through the show, I started bringing one mic level down and your volume jumped back up, so next time you want to set up this way, make sure you remind your soundman to keep them phased correctly." My first thought was "SHt Happens, thanks for the tip for next time" but my second thought was "wait a minute, we soundchecked, and everything was ok..." This was a new place for us, and the employees were all very friendly, and everyone had a good time, I'm not bashing the sound guy, the other bands sounded wonderful, couldn't hear my band for obvious reasons, but it's just something that perhaps needs some discussion. Thanks for any opinions! Link to comment Share on other sites More sharing options...
Members agedhorse Posted June 19, 2008 Members Share Posted June 19, 2008 Double-check that YOUR amp didn't have the (internal) speaker wiring reversed on one of the two speakers. That 's not uncommon and will result in terrible sounding "stereo". It's also possible that it was one of his mic cables or channel in the snake. It's another reason why the sound guy must pay additional to any stereo input source, especially when mixed to mono which he was also probably doing. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 My amp has been stereo mic'd for recording about 20 times and there was never a phase issue, save a naughty setup with an AB box and another amp, so I doubt any amp gremlins snuck inside and reversed the speaker pairs. Link to comment Share on other sites More sharing options...
Moderators ThudMaker Posted June 19, 2008 Moderators Share Posted June 19, 2008 .....He did. We soundchecked. Everything cool. ...My first thought was "SHt Happens, thanks for the tip for next time" but my second thought was "wait a minute, we soundchecked, and everything was ok...".....He probably soundchecked levels, not how everything fit beautifully in the mix. That was probably getting tweaked as you went along and he would have noticed it during full band play. Perfectly understandable. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 He probably soundchecked levels, not how everything fit beautifully in the mix. That was probably getting tweaked as you went along and he would have noticed it during full band play. Perfectly understandable. Correct, as the second band, we didn't get to play a song or two for overall mix. But if the issue was the two mics on the speakers, out of phase or whatever, kind of a mystery to me, how would that only be an issue with all the other instruments playing but not the amp by itself in a line-level check? Unless he only checked each mic individually for level and not both mics simultaeaeaouly? Link to comment Share on other sites More sharing options...
Moderators ThudMaker Posted June 19, 2008 Moderators Share Posted June 19, 2008 Correct, as the second band, we didn't get to play a song or two for overall mix. But if the issue was the two mics on the speakers, out of phase or whatever, kind of a mystery to me, how would that only be an issue with all the other instruments playing but not the amp by itself in a line-level check? Unless he only checked each mic individually for level and not both mics simultaeaeaouly?Because it's going to make that amp sound very thin in the context of the whole band. It might not have been that noticeable at the start or not something he paid much attention to. Especially in an environment where the goal is to get the band playing, not lay down Yes 90125. I'd say he gave you very valuable info, so that the next soundguy who mics the cab properly should be made aware of that possibility, too. It's always a possibility in that micing situation, whether or not you've personally experienced it. Link to comment Share on other sites More sharing options...
Members lonotes Posted June 19, 2008 Members Share Posted June 19, 2008 Question for AH; couldn't just a minor positioning error between the mics account for this? Whereas with one mic, this would not be a problem at all. Could that be another reason for the reluctance of sound techs to stereo mic an amp? Basically, double mic it and have to fiddle around with getting the positions of each mic just right so as to get the best tone *and* phasing, versus just stick one mic up in the right spot, and move on. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 Question for AH; couldn't just a minor positioning error between the mics account for this? Whereas with one mic, this would not be a problem at all. Could that be another reason for the reluctance of sound techs to stereo mic an amp? Basically, double mic it and have to fiddle around with getting the positions of each mic just right so as to get the best tone *and* phasing, versus just stick one mic up in the right spot, and move on. No no no no no no no. This topic is very specific on the type of amp being micd. This isn't some 2x12 or 4x12 cab. This is an amp that has different sounds coming out of each speaker. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 Sorry, if you meant pulling one mic off back to get both speakers.... I'm participating in several discussion forums at the moment.... sorry for the too-quick response. Link to comment Share on other sites More sharing options...
Members kevinnem Posted June 19, 2008 Members Share Posted June 19, 2008 Question for AH; couldn't just a minor positioning error between the mics account for this? Whereas with one mic, this would not be a problem at all. Could that be another reason for the reluctance of sound techs to stereo mic an amp? Basically, double mic it and have to fiddle around with getting the positions of each mic just right so as to get the best tone *and* phasing, versus just stick one mic up in the right spot, and move on. IF can can be so bold as to jump in here. It CAN be a problem with 1 mic. If the speakers where out of phase, then they still have cancelation at the mic (how much and nature of this cancelation are up to the details). IF the speakers were in phase, we can again STILL have cancelation issues, however, if the speakers are close together, and the mic is approximately between them OR is right in front of one of them, it should be okay. Link to comment Share on other sites More sharing options...
Members lonotes Posted June 19, 2008 Members Share Posted June 19, 2008 Sorry, if you meant pulling one mic off back to get both speakers.... I'm participating in several discussion forums at the moment.... sorry for the too-quick response. No prob. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 All youtube footage I've seen with bands using the JC120, in particular, a Talking Heads vid from 1980 live in Rome, there's only one mic on the JC120, right up on one speaker, but they have 4 JC120's.... and 4 Fender Twin Reverbs. 8 amps, 8 mics. I don't think this vid can be embedded due to copyright, but here's the link to youtube. http://www.youtube.com/watch?v=6g8lFmsCXhg 6g8lFmsCXhg For what it's worth, the last review we got was "sounds like any late 70's Talking Heads you care to mention" and damn I wish it were true. Link to comment Share on other sites More sharing options...
Members lonotes Posted June 19, 2008 Members Share Posted June 19, 2008 It CAN be a problem with 1 mic. If the speakers where out of phase, then they still have cancelation at the mic (how much and nature of this cancelation are up to the details). IF the speakers were in phase, we can again STILL have cancelation issues, however, if the speakers are close together, and the mic is approximately between them OR is right in front of one of them, it should be okay. But that's just the thing. The JC-120 is a different duck. One speaker does change phase as part of it's effect. The "chorus" part of Jazz/Chorus 120. At least I believe that the effect alters the phase of the output to one speaker while leaving the other unchanged. At least that's the way I believe that it works. If it doesn't, I'm going to attribute it to trolls or leprechauns, or some equally unassailable theory . Essentially I'm asking, does that make the mic placement more or less critical? Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 You can see clearly from 4:11 to 4:20 that one JC120 has the right speaker mic'd, and the other has the left speaker mic'd. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted June 19, 2008 CMS Author Share Posted June 19, 2008 Yeah, it could be that he checked levels individually, which he should have, and since there was no opportunity to check during a song, this is as far as things went. It's also possible that what he was hearing was the normal phasing changes that chorus will create. If the mics are mixed to mono, as phase approaches 180 degrees, the signals will cancel, lowering volume, and as it reverts to 0 degrees, volume increases. It'll swirl in and out of that. I don't know whether the effect is 'on' all the time with that amp or not. If it can be shut off, is there any guarantee that the signals are in phase, or are they wherever they were at the moment it was shut off? Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 Of course! I imagine that you're certainly more qualified/experienced than I am. But that's just the thing. The JC-120 is a different duck. One speaker does change phase as part of it's effect. The "chorus" part of Jazz/Chorus 120. At least I believe that the effect alters the phase of the output to one speaker while leaving the other unchanged. At least that's the way I believe that it works. If it doesn't, I'm going to attribute it to trolls or leprechauns, or some equally unassailable theory . Essentially I'm asking, does that make the mic placement more or less critical? That makes me feel like Julia Roberts in a Southern salon spilling orange juice on my face. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 Yeah, it could be that he checked levels individually, which he should have, and since there was no opportunity to check during a song, this is as far as things went.It's also possible that what he was hearing was the normal phasing changes that chorus will create. If the mics are mixed to mono, as phase approaches 180 degrees, the signals will cancel, lowering volume, and as it reverts to 0 degrees, volume increases. It'll swirl in and out of that. I don't know whether the effect is 'on' all the time with that amp or not. If it can be shut off, is there any guarantee that the signals are in phase, or are they wherever they were at the moment it was shut off? That's a good question. I use the chorus effect about 50% of the time. It's not a stomp box thing, so in a song, it's on the whole song, or it's off the whole song. Link to comment Share on other sites More sharing options...
Members lonotes Posted June 19, 2008 Members Share Posted June 19, 2008 I think that it does operate like a stomp box in the sense that when turned off, the phasing circuit is bypassed. So it would revert to a normal, in phase signal. A friend of mine still has one, but he hasn't used it for nearly twenty years. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 19, 2008 Author Members Share Posted June 19, 2008 What I mean is it isn't something I turn on and off during a song, thereby creating additional confusion for sound man. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted June 19, 2008 CMS Author Share Posted June 19, 2008 What I mean is it isn't something I turn on and off during a song, thereby creating additional confusion for sound man. lonotes is referring to the amp behaving like a stompbox in that when the effect is "off", it's fully bypassed. Link to comment Share on other sites More sharing options...
Members daklander Posted June 20, 2008 Members Share Posted June 20, 2008 Would not the 3 to 1 distance ratio apply here as well as mic'ing an acoustic guitar? Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 20, 2008 Author Members Share Posted June 20, 2008 Any comments on how the JC's are mic'd on the talking heads vid? Link to comment Share on other sites More sharing options...
Members agedhorse Posted June 20, 2008 Members Share Posted June 20, 2008 A mic that is out of phase will cancel most of the phase coherent program, though there will be a ton of comb filterd slop. Maybe the sound guy had a bad cable w/ pin 2 & 3 reversed. Frankly, you opened your own can of worms on this one, and it's a good lesson in keeping things as simple as possible to avoid such problems that may or may not be out of your control in the future. Also, if the system or the channels are downmixed to mono, the phase shifts between channels will translate to amplitude changes on the mono signal and the effect will be totally different. It's the risk you take trying to be fancier than the sitaution allows. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted June 20, 2008 Author Members Share Posted June 20, 2008 Ok I'll just go get a Line 6 and be done with it all. Link to comment Share on other sites More sharing options...
Members Neonfacelift Posted June 20, 2008 Members Share Posted June 20, 2008 Ok I'll just go get a Line 6 and be done with it all. It would make everyone's life easier, and you get your stereo to boot. Left and right outputs into two DI's. Doesn't get much easier. Much less for you to haul, too! Link to comment Share on other sites More sharing options...
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