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I don't get how preamps work with snakes

Discussion in 'Preamps / Channel Strips' started by ClarkJaman, Oct 10, 2012.

  1. ClarkJaman

    ClarkJaman Active Member

    I'm mostly a recording guy, but I do the odd live sound gig. I've done a couple now with analog snakes that split the signals to both the FOH booth, and the monitor console. But I don't get how those work, in terms of preamps to microphones? Are there are two gain knobs controlling two preamps to one mic...? How is that possible? I am just a young rookie, so if any of you veterans can explain how this works I would really appreciate it.

    Pax Caritas et lol,
    -Clark
     
  2. Kurt Foster

    Kurt Foster Distinguished Member

    passive split with transformer isolation.
     
  3. Boswell

    Boswell Moderator Distinguished Member

    The splitters send the mic signal to both sets of equipment, so you need independent pre-amps at both places. There is usually some signal amplitude loss with splitting, but with most types of live gigs, it's not often noticible.

    Good-quaility splitters are carefully arranged so that only one set of pre-amps can supply phantom power to the microphones. You need to agree with the FOH engineer which set that is, but the normal arrangement for recording is that the FOH board supplies it. When there are separate FOH and monitor consoles, it could be either way.
     
  4. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    Often there is a third split to recording in addition to the main and monitor splits. Each split needs its own preamplifier.

    Sometimes people will do a split from the inserts or direct outputs of a mixer. That will be after the mixer's preamps so that sort of split is at line level and doesn't need more preamps, but it makes the split dependent on the mixer. If the person running the live mix isn't conservative enough with his levels he may clip some signals. That's not a big deal live because it's done and over with so fast, but if it affects the recording there's not really any way to fix it. That's one reason live recordings are generally done with a mic split and separate preamps.
     
  5. ClarkJaman

    ClarkJaman Active Member

    Makes sense. Thanks guys! :)
     
  6. RemyRAD

    RemyRAD Well-Known Member

    I know this is a few days late but I thought I would chime in here?

    You'll actually find three types of common splitters for microphones utilizing XLR connectors. The least expensive and most obvious types are frequently for use in small my clubs with an average PA House mixer and a smaller one for the monitor mixer. These are frequently and simply passive parallel wire connections. These types can cause some interaction between mixers due to their parallel direct connections. Which usually isn't a problem in a small nightclub scenario.

    The most common professional types are the transformer splitters. So what occurs here is what is known as the first split. This is the direct connection from the microphone to the front of house mixer. The splitter is then also connected across that microphone connection which provides transformer isolated, same output level, outputs. These splitter Transformers do not pass phantom power. Doesn't even matter if you have your phantom power on. The DC does not go through. Only the first split device can feed the phantom power to microphones that require it. Transformers of these types can be anything from $.98 Radio Shaft transistor radio Transformers to the top shelf units made by Dean Jensen, Reichenbach, Cinemag, others. And run about $100 each or more. And the level that goes into these Transformers, comes out at the same level, which is highly shielded and protected.

    Then there are the active splitters. I hate those things. And here's why: they actually have a microphone preamplifier built into the splitter. This then allows them to provide active output splits at either the original very low, microphone levels generally rated around -50 DB. Or, you can hit a switch and make it come out at +4 DB, full studio line level which is about 54 DB hire that a microphone actually outputs. And you don't want that plugged into your microphone input when that happens. Because that's virtually a guarantee you'll blow something out. Maybe not the microphone preamp itself but certainly the tweeters in your speaker/speakers. It also gets the blood pumping. I worked with the big roadshow PA companies that said they would give me microphone level on these huge all day rock 'n roll radio music festivals. And I would get feeds all over the place. Certainly not as they had indicated. Because buttons got pushed that nobody was looking at. So those things burned my ass. And who the heck wants some crappy compromise microphone preamp in front of my Neve and API stuff? I'd rather just have another coil of wire slung across the microphone. Signal purity my ass. So you also get extra amplified noise which you could conceivably get blamed for later. So beware of those better active splitters. They're crap I tell ya. They are poor excuse for no Transformers.

    I don't even care if I get the first split. Though that is a luxury fraught with other complications. Most recording trucks like mine want the first split. And so do I but then you have to be sending out the Phantom power up generally longer lines. DC levels suffer over distance. So if you're working with 500 feet of 24gauge snake cable, your +48 won't be +48 at the other end. And then what happens to the PA system if you blow a fuse while you're feeding Phantom power? K00STER McAllister might want that kind of responsibility but I don't. And that's why I'll take the split anytime. Doesn't matter if it's less than what it should sound like when you have API or Neve. When ya don't have that, it's still going to sound fine. We are still talking about a couple of decimal points down and that's all. If you want to be anal about it, you can hear the difference. It's a difference that doesn't really make any difference. Certainly not with rock and roll. Opera I might feel different about. But then those are usually the microphones I have had the stage crew hangup for me. Usually separate from their system except for some kind of announcement microphone. And who cares about that? Oh somebody's going to sing the national anthem. Big deal. It's the national anthem. As long as it's not Roseanne Barr singing it while grabbing at her crotch I'm OK with it. I mean I actually thought that was a good Michael Jackson she pulled? Or tried to? And that you would have wanted to pick up the ambient mic from the PA system anyhow LOL. Roseanne Barr not Michael Jackson that is. Michael would make that neat little squeak when he did that. I never recorded Michael. Nevertheless, look out for those active splitters.

    It's bad for you if the PA guys have problems with their microphone patching. When multiple bands are performing, you'll generally get microphone input run down sheets. And so when your lead singer is supposed to be on input 17 and you can't find them anywhere on your console, it becomes big fun. Then you find yourself soloing all 48 of your inputs or more and no lead singer. 10 minutes into the set, the radio stations and MTV are going crazy. Then ya have to send down your A.-2, through 30,000 of the 65,000 people in the stadium to get to the PA guys. Then you find out they put her on input you don't even have. And that's even bigger fun. And then it's line level! Great. Swell. Thankfully I never had any problems taking line level inputs to my microphone inputs. Proper resistive padding is included on most professional old-school microphone preamp designs. And that's really the only time you can effectively run a microphone preamp into a microphone preamp without remorse. It's a compromise I know but when I'm good, it's good. It's fine and nobody knows the difference. I know but I'm not telling. I guess I told? The jig is up. I've failed... now everybody knows... 15 years later. Or was that 17?

    I had a Sphere case of rock 'n roll recording.
    Mx. Remy Ann David
     
  7. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    I would think a big reason to take the transformer split at the remote truck would be to prevent ground problems from whatever weird power the truck gets.
     
  8. RemyRAD

    RemyRAD Well-Known Member

    You'd think that might be the case but I actually found out otherwise, curly on. At first I started the truck with a direct coupled 208-240 3 phase/1 phase volts AC. And while I didn't have many problems, there were some problems. Noise susceptibility was still high, until the electrical isolation, 7.5 kW transformer went in. Then everything got real quiet. Balanced power like quiet. While my internal power was not ± 60 V on each Edison lug, the AC power was still being handled with the transformer in a balanced fashion.

    With that electrical power isolation transformer, I was actually even able to take non-transformer, hardwire, passive splits without problems. Couldn't do that before the power isolation transformer. But yeah, I actually preferred taking the microphone transformer split. But the other remote truck owners, they don't want to split, they want the primary Tap/first split for the ultimate specifications you get that way. You know how anal everybody is in this business? This is where my, I guess nonprofessional attitude, regarding my feelings of good works, I can use it. I was never going for the ultimate naked decibel. I've always known it's an imperfect world and I'm not out to change that. I'm just very good at thinking on my feet and outside of the box and get it on the air now " four, three, go to black, two, we're up. No time then to evaluate quality or make any decisions. You just push the mix right up. That fast. You roll with it. You get real good real fast that way. Maybe that's why everybody thinks I'm a fast woman? It takes me much longer with some other things a little too personal to go into here... dammit my batteries are dead. Not the trucks. Though I could personally use a jumpstart myself.

    Most of the remote truck owners didn't want to take the split because it sounded different and added about .002% extra THD. And I say BFD to that kind of inconsequential nonsense. It's like getting upset about a fingerprint on the paint job of your finely polished automobile. But let's face it... people are like that the world over. You live longer if you don't let that little stuff get to you. I've also never really ever blamed my equipment if I couldn't get a mix or recording to sound exactly the way I wanted it to. I've never really considered my equipment to be anything less than operationally usable. Of course I love certain things over other stuff but I really don't care that much. That's not to say that I don't care about the sound that I ultimately achieve. I know everything I do is professional sounding. Some days you're more on the mark than others. Isn't that true of everybody? Of course. You get paid when the meters move basically the same way as when you started LOL. At least that's how the TV guys do it LOL. You know, those video guys that think they know something about audio. Ha, right. In their wildest dreams.

    I'll take it anyway I can get it. Yes... I am that kind of girl.
    Mx. Remy Ann David
     

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