Cleaning funky mixer signals

[mosc]

I have a Mackie 1642VLZ PRO mixer (analog only). It has a flaky intermittent problem.

Sometimes, one channel of the master output will sound very distorted, weak and very tinny. It almost sounds like a very dirty patch cord connection. It's not that, I don't think. Through years of trial and error I have found that if I run a very strong signal through the mixer I can clean up that channel distortion problem for a while. I do this by turning up my strongest synth all the way, turn up it's pots, turn up the gain trim and turn up the master output. I also turn down my amp.

The distortion comes back in anywhere from a few hours to a month or two. This is very annoying, obviously. Has anyone else see this kind of problem before? Any suggestions? Could this actually be a bad patch cord or jack?

BTW, I hate it when this happens...

[deknow]

the obvious first test is to tap the associated fader (down, not sliding). taking these things apart generally requires removal of a bunch of knobs, but is probably necessary.

if you do bother to take the thing apart (which depends on how many channels you generally use), i would poke around the suspect channel with freeze spray and a heat gun...wiggle anything wiggleable, and even slight flexing of the board. if you can isolate a small area where the problem lies, you are that much closer. obviously, a scope or audio probe would be helpful as well (you can feed the same signal to a good input and the bad one....start at the input and move through the channel strip comparing the known good channel to the bad one).

in general, i doubt it would be cost effective to bring it to a tech. if you have time to screw with it, do so, but these are designed to be disposable (unlike the old mixers with separate boards for each channel).


deknow

[mosc]

Yes, disposable is right. I haven't been able to identify a single knob or fader that is the cause. If this keeps up, I'll just get something to replace it.

At a recent gig, my little Behringer 1202 got a bit smashed and the master output fader got bent over. One of the output channels died. I figured the fader just got pulled a bit off of the board. After taking about a dozen screws out, I was able to pull off the back cover. It appears that to fix it, I'd have to pull of the front panel. That would be a huge job - lots more screws and every knob would have to be removed. I just bought a new one to replace it. It's amazing how they can sell these products so cheaply.

[astroid power-up!]

I use the inserts on my mackie so as to not color the sound with the crappy mackie preamps going in. i was having a similar problem to you the other day, when i wouldn't hear anything, but then all of a sudden, screaming into the mic, it would get a level, and then peter out. turns out that i had to half-patch it (just stick it in halfway). totally solved the problem. don't know if that's your prob, but maybe worth a try.

[mosc]

Sounds similar. Your problem appears to indicate bad jacks. I suspect that could be the problem too on my system. When patching my Moog Modular I sometimes get these kinds of symptoms and they can be fixed by turning a patch cord in the socket to "clean it". Maybe that's what you did.

I wouldn't say your problem is "totally fixed" if that is the case - more like fixed temporarily. Are you running with the cable half patched permanently now?

[deknow]

....assuming you don't have special large contact area plated jacks (i don't know if they even exist, but i can imagine them), a good cleaning method is to find a spare 1/4" plug (if it's slightly on the small side, it's probaby better). use some pliers or a file to rough up the areas of contact just a little bit. use these with some contact cleaner (or even just electronics grade alcohol...the kind without all the water), and rotate them around a little in the socket. this will scratch off the corrosion on the jack specifically where it makes contact with the plug.

deknow

[elektro80]

Mosc, that prob sounds like a sick cap or two. I have experienced similar shit on old Allen and Heath and Tascam consoles. It took me 3 weeks to find the sick component in the Tascam.

[jksuperstar]

A can of air (electronics air-in-a-can type) on all the pots, and especially sliders, never hurts. I've personally resurrected 1 control surface and 3 mixers this way (all of them where dirty sliders used in the homes of people who smoke).

[mosc]

Caps sound like a logical source.

That would explain how a high voltage could clear it up. A spike could burn through an imperfection inside a capacitor.

Along the same lines, it might be a cold solder joint, but a bad cap is probably more sensitive to voltages.

Good idea about cleaning pots, but in this case I don't think it's the problem.

So, I'm forced to conclude that the best way to fix this intermittent crackle is to replace it.

Now the question is, with what?

New topic?

[elektro80]

I have seen the schematics for the VLZ once and I guess it shouldn´t be that hard to find the sick cap/caps. Parts shouldn´t be very expensive either.

If you want to replace the mixer the first obvious question is : What do you need it for? Do you need channel strips with eq? Mic preamps? Do you need it for recording audio or just for performance work?

[deknow]

...although i'm on a "record live to 2 track" wig these days, buying a harddisk recorder that is also a mixer has many advantages (none of them being simple, os free, analog electronics). i've done a number of live recordings this way. the downside is that once you have the individual tracks, it kind of demands that you do some editing. 2 track you either use it or not.

deknow

[elektro80]

Deknow, that is a good suggestion as such, but personally I am not completely convinced about the audio quality of the budget units.. and they all are budget units. The concept is great however.

I recently visited a friend in BCN who has both the Speck XTRAMIX and the LiLo.
Both are insanely good and pretty much proves that it still makes sense to use analog mixing gear. However, I am pretty sure mosc doesn´t need anything like this, but man.. those devices are naughty and immensely cool.
http://www.speck.com/lilo/lilo.shtml
http://www.speck.com/xmix_2.shtml

Mosc has the MOTU 828 mrk2 interface, and I am pretty sure he doesn´t really need a mixer for making recordings, unless he uses the mixer for monitoring and monitoring submixes etc etc. In his case it might make better sense to get some good preamps/di boxes and some analog compressors or whatever and some cheap but decent mixer for montoring setups.

[mosc]

In my studio, stuff goes to the Mackie mixer for monitoring. For recording, I send the instruments to the submixes. Having only 4 channels is a problem sometimes. 8 would be much better. Almost everything is line level and I hardly ever use the mixers EQ function. I don't need fancy mic amps or really groovy EQ. The fact that you can't bypass the EQ on the Mackie is a bit of an aggravation.

These high-end line mixers are great, but I'm not interested in spending that kind of dough.

[elektro80]

With an interface like the 828 you should be able to use that one for the basic monitoring mixes. You might however need a console and efx units for setting up elaborate monitoring mixes. This would be on the outputs of the 828 and not for the inputs. I cannot see why you should need a mixer for the signal inputs to the 828. Have you really looked into what you can do with the 828? Perhaps you should rethink the signal routing?

Trivia: The reason you might want to use efx on the monitoring mix is that you then can have the signals as wet you like.. and play with a live wet mix.. and still have the actual recording dry and fairly unprocessed. When you end the basic tracking part of the production you then "transfer" the efx settings to the software efx plugins or whatever you prefer using.
It is common practice to think two different monitoring setups:
1. The engineer´s high quality state of the art monitoring of what is actually going on
and
2. The monitoring for the muscians.
In your case you are both the engineer and the musician so I guess you will have to consider a setup that makes sense for you.

[mosc]

[elektro80]

Allen and Heath had this pretty decent recording console a few years back. I cannot remember the model name, but I have heard that many of these are available for a fairly nice price secondhand. These were made for ADAT and have a good 8 track routing and channel assignment. I have used one of these and I liked both the features and the sound quality. these went for something like 1500-2100 USD back then. These should be possible to get for like 500-600 USD now.

I am still not completely convinced about the digital mixers with onboard efx and whatnot. I cannot see why you should want to take the signal into the digital domain stage before the 828.
As for basic signal level management pre the recording device inputs I usually recommed analog compressors/limiters. It is far easier to handle headroom issues on very hot and unpredictable signal sources using good quality analog gear than with budget digital consoles with onboard efx. And, surprise.. it sounds far better too.

That Behringer digital mixer is very cheap right now and it is perfect for quick and dirty monitoring mixes, but I wouldn´t recommend using it as a frontend device in your recording chain. What you might need is a very basic line level mixer with direct outs and then some very good analog compressors/limiters.

The Mackie Onyx mixers are not suited for your studio I guess. Those are very basic Mackie style live mixers with a firewire feed to a computer of the channels. There is only a stereo return to the console from the computer. This means that it is completely useless for serious modern production work. This doesn´t mean that these products are bad. They are simply designed for live use and live/location recordings.

Even though I think the budget digital consoles/combo recorders aren´t good enough, they are of course far better than the PortaStudio devices of the 80s. I am convinced that they can be used for making very decent recordings, but in your case I don´t think such a product is suitable. You would be downgrading your signal chain and not taking what you already have even further.

[mosc]

Sorry to hear about your not liking the sound quality of the Behringer digital mixers. These may be just the thing for the new sound. It used to be tape and DBX or Dolby processing through analog mixers. Now its anything goes with many movements through AD/DA/AD/DA/AD changes.

After my experience with Mackie, I would be hard pressed to get another one. I mean, why replace this one - becuase it doens't work.

Lots of people say the Mackies sound much better than the Behringers. I don't think the Mackie sounds that great, so I'm really scared to use the Behringer.

I just got a new Behringer 1202 to use as a live performance mixer and line driver. I'm going to do a careful listening comparison with the Mackie and deside for myself.

[elektro80]

I think I did start a thread way back about the behringer digital mixer. It is quite OK for live use and monitoring. It sounds pretty decent when compared with similar Yamaha gear. I do however think that it is not suited for recording use. The routing and the overall topology of this mixer is also a bit weird and I personally think it does not add much as a recording console. It is however great for many monitoring tasks.
As for analog gear, I am recommending analog gear but I am not suggesting you switch back to tape. Digital recording is quite decent these days.

[elektro80]

[deknow]

personally, i think the behringer boards are as good as you need, unless you want to go to an allen$heath (that's a typo, but i like it).

deknow

[djfoxyfox]

[astroid power-up!]

yes, that's what it does, it might be flakey operation, but it works reliably.

[mosc]

[mosc]

I was doing some recording. Very simple, just record the G2 straight - no effects or processing. The Machie submix going direct into the MOTU. When I listened very carefully, I noticed noise and distortion.

I hooked up my new $80 Behringer UB 1202 and it was much quieter and less distorted sounding.

Then I recorded with the G2 plugged direct into the MOTU 828MKII. No comparison - much less noise and distortion. .

So the logical thing is to run all my signals directly into the MOTU and do my recording and monitoring through the computer. It has four stereo busses. That's pretty OK.

The problem is to adjust the input levels one must use a computer application.

[djfoxyfox]