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I just got my Mackie DFX-12 and it did not quite perform to wad i visualised. I avoided Behringer as all says :p... ok, I did not connect anything to the inputs and tested the noise and it hissed real bad at +50db and faders at Unity gain... ("Full" setting). The hiss disappears (unnoticed) at about +35db:"2 o'clock". Is this normal?

Another thing is when i connected the outs to a guitar amp, has an irritating hum, but no hums when i connect to audio amps and PC speakers... is there an explanation for this? Both equips are connected to the same power socket...

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Cucco Mon, 10/17/2005 - 08:15

yeah, that's kind of normal for budget pres and cheap console pres.

This is why you don't want to run ribbons through these kinds of pres.

Why does this happen? Hard to say. Perhaps the folks that know the inner workings of a circuit, such as Kev could answer this one better.

It is fairly normal though.

Many or Most high-end pres simply don't do this. I can run my Graces, Trues, Summits, Aphexs, and others wide open (max gain) and not hear any additional noise. (That is, above and beyond the noise floor +60dB of gain or so...)

J.

anonymous Mon, 10/17/2005 - 09:20

yeah it is kinda normal in that range...

by the way how did you powered the mixer? is it in a chain of outlet's, say from an extension cable?? or similar??, the reason why i am asking is, i had some bad problems with noise in my first home set-up many years ago, untill a friend of mine gave me the tip to try around with changing the order of my plugs, i was running everything from 3 wal loutlets and then used multi extensions, just the simple swopping around the order of units plugged, reduced about 30 percent overall noise, i can't technically explain why, but fact is it works, i still do that, best way is to plug everything and run all faders open / gains high, and then start to unplug two units and swopp, and so on... untill you find an order that reduces the noise, it really works.

it does not improve the quality of your pres :-) but it will help reducing some overall noise...

anonymous Mon, 10/17/2005 - 09:23

yeah it is kinda normal in that range...

by the way how did you powered the mixer? is it in a chain of outlet's, say from an extension cable?? or similar??, the reason why i am asking is, i had some bad problems with noise in my first home set-up many years ago, untill a friend of mine gave me the tip to try around with changing the order of my plugs, i was running everything from 3 wal loutlets and then used multi extensions, just the simple swopping around the order of units plugged, reduced about 30 percent overall noise, i can't technically explain why, but fact is it works, i still do that, best way is to plug everything and run all faders open / gains high, and then start to unplug two units and swopp, and so on... untill you find an order that reduces the noise, it really works.

it does not improve the quality of your pres, thou... :-) but it will help reducing some overall noise...

JoeH Mon, 10/17/2005 - 10:04

I may be mistaken, but the DFX series are not sold as any kind of audiophile/recording mixer. According to Mackie's website, this is a stage-mixer, designed for musicians to use onstage, without an FOH mixer. There are a lot of useful monitor routing features, as well as DSP effects (Reverb, echo, etc.)

They certainly do say a lot of things on their webpage about how quiet and flexible the thing is, but I didn't see anything about the preamps, so I'm guessing they're probably just the VLZ's, perhaps not even the VLZ pro's or XDR pre's. (Just a hunch; I don't know for sure...)

These days, I'd consider the ONYX for anything really quiet and audiophile quality. I have used (and still do) the VLZ Pro XDR mixers for a lot of things with great results, but again, with the ONYX now available as full-out mixers or 4x or 8x preamps, there's no need to suffer with a low-end mixer anymore.

As for the noise level, you may indeed want to check your grounding scheme, as well as your power amp's true settings and what it wants to "see" for an input. As for the hum in your guitar amp; I'm not at all surprised. If you used the "instrument" input of the guitar amp, you're sending +4 level background noise (AND hum) into something that wants to see millivolts from a guitar pickup. BIG difference. It WILL sound like Sh*T that way.

Also, if your power amp is a consumer device, perhaps an unbalanced -10 nominal level device, and you're hitting it with +4 from the Mackie's balanced out, it may indeed make a lot of noise. Personally, I have NEVER, EVER had a background/system-noise problem with any Mackie device that was audible during a live gig with pro audio gear. Although I don't have hands-on experience with the DFX series, I would expect the same thing from that line.

Perhaps there's something else amiss.... ?

Cucco Mon, 10/17/2005 - 10:20

The electricity issue is a real one. Since current in most cases is AC, where you place the device on the surge strip can have a HUGE impact on its sound.

Personally, I like to use isolated devices such as surge protectors/line filters which isolate each receptacle or a pair or grouping of receptacles.

Joe -

You REALLY seem to like the Onyx stuff. Do you think it's viable for most on-location recording with Firewire directly into Sequoia? Both the pres and the A/D are "up to snuff?"

J.

Kev Wed, 10/19/2005 - 13:42

kevinlimse wrote: Another thing is when i connected the outs to a guitar amp, has an irritating hum, but no hums when i connect to audio amps and PC speakers... is there an explanation for this? Both equips are connected to the same power socket...

guitar amp has very high input impedance and lots of gain.
Of course it will have hum and hiss if you have the wrong stuff plugged into it.

to re-amplify, you may need an interface box or adapter

hold the end of the guitar lead and you can get all sorts of noises and perhaps even AM radio

the normal high level inputs like audio amps and PC speakerds don't have such a high input imp and not so much gain.
The noises are still there but way down in the noise floor.
Some of these units will be balance input and this offers some noise canceling