You have to.
DJ's often have what people would think is a much simpler audio path. Often they do, but just because they have two turntables or playing decks, it's not that different from a concert sound system when you really think about it, except in scale of channels.
In his case, he has to troubleshoot the mixer and the decks as playback sources TO the mixer. Since he's adding in Serrato and that interface, now he's got to troubleshoot that AND the laptop AND the source files. Along with the Serrato interface, that means checking the control disc as well as the INPUTS into Serrato as the OUTPUTS from the Serrato interface.
He's dealing with 4-6 channels of audio. In my case, I may be troubleshooting up to 76 or more channels, plus all the patch points in the patchbays, FX, outboard, mics, wireless and more, but the concept is the same: Single out one at a time and find where the problem is. It's no different.
Having had some really good views of how Serrato works by the guy I was talking about in the previous post, what I noted was that it adds a whole new set of complications. I love computers, no doubt about it. My "day job" surrounds itself with comptuters and networking. Again, signal flow and troubleshooting. But, Serrato is interesting. Normally, I see two turntables plugged in, I see those as "Audio sources" for playback. Serrato totally hoses that concept up. The turntables still work as audio sources, but they terminate into the Serrato interface, and the Serrato interface is listening on those inputs for control signals. The USB connection serves of course as a bridge for control instructions from the turntables going into and manipulating the computer, while the OUTPUTS on the Serrato interface are driven from audio ON the computer and that in turn is driving the mixer's inputs. Now you have multiple things to troubleshoot. Grounding on the turntables, mixer settings(Line/Phono), cable issues, integrity of the control discs, integrity of the USB cable, integrity of the interface, integrity of the source data. On top of all that, you have to deal with issues that may be the computer itself. Now we're tracking utilization of resources, hardware desing, other apps running, TSR's, memory, hard drive and CPU issues, and then we're back to integrity of the data issues again.
Here's a great example. I was doing a major event at the end of May. I had a problem with Channel 25 on my console, but oddly enough, I had a problem with Channel 25 on my console since January, but back then I didn't have the chance to troublshoot. At this event at the end of may, I had my 2A continue to mix, while my other assistant assisted him. I took out a panel out of the back of the rack and had to poke around. Mind you, we're talking over 400 connections terminating in that rack and I'm poking around in there during a LIVE event trying to troubleshoot. The snake was fine, the mics were fine, the DI's were fine and I by-passed the installed wiring and went direct to the channel and that worked, which means the insert points were correct. This left it down to the patch panel where the stage box meets the console in that rack. Turns out for some strange reason, 25 INPUT was pulled loose. There ya go. Plugged it in, buzz vanished, console solid again. Of course, simply muting also removed the buzz but wasn't resolving the issue. Definately NOT how I would recommend doing things but you do what you can when you can. Since I can't move a 400 pound console on my own, much less set it on the stand and remove the case lid on my own, I have to do maintenance when I can.
DJs using Serrato run the risk of having a whole new slew of problems to troubleshoot. I'm not saying "Hey, let's ditch Serrato" because that's counter-productive. Ideally, computer-based applications should run on a purpose-optimized computer. But let's face it, these things are expensive, especially laptops and even more with Mac laptops, we try to get everything we can with them. In some cases, we're causing ourselves problems.
Let's look at ProTools. I can talk smack about Digi, I've been using their stuff since the Session 8 and 442 interfaces. Even with an optimized system, Apple or Windows make updates, and then ProTools stops working. Then we have to wait for Digi to come up with the fixed version. And then the process repeats. In my case, Mac updates keep slamming ProTools, so I have to kick over and run it as a PC, but my MacBook pro was bought with this concept in mind.
We often don't optimize our computers for our MIDI apps, ProTools or other production suites, or even things like Serrato.
When you work at an extremely high level, one of the things that develop is that eye and ear for detail, as most of you SHOULD develop over your years of working. At first it's "I got it working", then it comes to "how do I make it work better" and then it's onto new gear and starting portions of the process over again. You run into problems and learn to troubleshoot them.
Even I get stumped from time to time. I had a 64 LED Pro fail on me at an event. I IM Jingles, who was unable to help me as quickly as I needed help. That's fine though, because he, being sepparated from the event, didn't have to deal with my stress over it and was able to confirm that "hey, you did what you could as far as troubleshooting", which is what I needed to hear. In a panic and under the crunch, you can overlook things, which fortunately it appears I didn't. My biggest problem was that I did NOT have a volt meter on hand and the fuse looked good, but that was the failure point. Even if I did diagnose a bad fuse on site, I had no spares, so it would have done no good. Now I have spares, bought from ADJ directly. Lesson learned: Why the hell did I NOT have my volt meter with me this time!!
Not to knock DJ's, but they are typically using stuff that is entirely at their fingertips. This is a HUGE advantage for them. Why? Anywhere there is a problem is on their table. That's a luxury to me. I have to also troubleshoot the stage. Is phantom power on or needed for that channel? Active or passive DI? Proper switch settings on DI's need to be set as well. Microphones set up properly(some have switches that need to be adjusted). Just a whole new set of toys and tools that need to be examined and troubleshoot.
When you're on the road and your survival depends on your quick wits and skills, you become really good really quick. Again, it's a much greater skill set for an audio engineer running a concert system, but just as important for a DJ to do as well. Downtime isn't a option. Your gear is your "life" and you have to be able to rely on it.
Not thoroughly or completely troubleshooting your situation is only shorting yourself. Stuff does fail. Things do need to be replaced. Bad stuff happens. You have to isolate the exact cause of failure, no matter what it is. Sometimes you get lucky and find it right away, and that's all well and good and hey, take it, you won and got off easy. That's just as valid and important as really having to grind down and find the issue. But sometimes finding the problem isn't sufficient, because sometimes even if you've fixed the problem is that you may not have fully addressed the problem. Its not just enough to fix it, it's also necessary to know WHY the problem happened.
"Why is my system buzzing and humming"? Well, you've got a ground loop issue.
"Why do I have a ground loop issue"? Because your mix position is plugged in a different circuit than the speakers/amps. This problem is more common for ME than for DJ's, who often are up on stage with their gear.
"Well, how do I fix it?" Good question. Sometimes you can't fix it, because it has to do with bad electrical practices at the venue.
"So, what, I just gotta live with this?" No, you don't.
"Since it's a grounding issue, can't I just use those ground lifting plugs and be done with it? OrI can just bust those grounding pins off." Yes, you can, but you've now made an unsafe situation and you could KILL someone. In this case, you may have solved the problem, but in reality is you have caused a dangerous situation that can end with someone dying.
"Well, the how am I going to get that hum out?" You can go out back and shoot yourself, or you can learn to address the issue.
I have ground lifts on my stage box, which will often resolve such issues, both in inputs and returns. But that can't always do it for me.
One of the simplest items is to have an EbTech hum eliminator. Of course, you need to have some adaptor cables as necessary to interface with it. These devices have worked very well for me.
Using a transformer to break the grounding issue safely maintains that ground while breaking the issue that was causing the problem in the first place.
Ebtech also makes versions that don't tie into your audio cabling, it is something that plugs into your power, doing the same thing at an electrical/AC level.
I DO NOT carry any of these little "ground lift" plugs that you get at the hardware store for a dollar. That loop or spade on there is intended to go onto the screw that holds the plate on the wall, which is connected to ground, when you have those ancient 2-wire receptacles. That is what those things are for: using modern 3-prong gear SAFELY on houses with older 2-prong receptacles(that are still 3 prong compatible!) Here's your hint and a half: It has 3 prongs on there for a reason. If the unit is designed for a 2-prong cable, it's been designed for that. It's safety.
So, we've seen how we can fix a problem without addressing it properly.
Same goes true for DJBigMike602. It does not sound like he's thoroughly troubleshooting his rig.
Now, let's just say that these CDI500MP3's are defective, then he's vindicated in saying that they are defective. But he's not entirely there yet but he has proven that one has failed, but not the other. It could very well be that some of the control signal information from his "factory produced Serrato control discs) is being dinked up by the DSP, DAC or other filters in the unit. This would mean that the deck itself is fine, but that the decks are just simply hating those control CD's. Let's look at this at a higher level:
Take 2 CD player by DIFFERENT companies and put them on a very high resolution system using TWO identical CD's. I will guarantee that BOTH will sound different, often slightly. NOT all CD players are created equal.
Not to ding American Audio, but perhaps the CDI500MP3 may simply NOT be the right unit for use with Serrato. I suggest you get to a music store and try this stuff out with your Serrato interface but with different decks, even if it means looking at different brands.
Sometimes the "RIGHT TOOL" is not the "RIGHT TOOL" for the job. Just because it CAN do the job doesn't mean it SHOULD do the job. In some cases, such as microphones, it can be subjective. Like I like the Audix i5 better on snare than the Shure SM57. Both will get the job done, but in my opinion I like the i5 better, but I've worked with snares where based on the player and tuning, the SM57 worked better. So there ya go. case and point is that while the CDi500MP3 may be able to do the job based on what it is, maybe it's not the right tool based on how it operates. Doesn't mean upgrading will fix the issue. This is an issue where you need to get some real hands on and trials to ensure you get the right gear. Any music store that gives a crap about their customers will do what they can do try to help them make the right purchases.
DJBigMike602 isn't an idiot. He's just not being thorough enough. What does he have in his favor? He's not afraid to talk to others and ask for help. This means he cares enough to try to resolve and fix his problems and knows when he's outside his realm of knowledge. This will in turn expand his knowledge. He's also helping show that "there's no such thing as a stupid question", and he's not afraid to ask them. That's two in his favor right there. The third is that he wants resolve for his issue and it sounds like he's willing to put in the effort to get there. But, what goes against him is that he takes too long to resolve things. I bet that's a money issue.