DJ Mixers vs "band" mixers

I know that the issue has been raised before many times, but a search seems to indicate that the responses (get a band type line mixer - Mackie etc) are buried in reponses to other threads. Maybe the issue should be documented and then added to the Wiki?

I guess what is confusing to me is what the "problem" is with "DJ Mixers". Is it ALL "DJ mixers" that are the problem?

What I am thinking is that the majority of DJ mixers are budget priced (ie under $400), are analog and send the signal path through 2 or more "sliders" (the line channel and the main output - the ususally ALSO go thorugh the cross fader as well)
Its the fact that quality sliders are expensive (say $50 a pop and your mixer rapidly becomes a $1K mixer)and that an alternate solution (using the slider to control a VCA - ie the signal does NOT travel through the slider at all) is also expensive.

What seems to be my experience is that the higher end DJ mixers (Rane, Pioneer DJM- 600 and up, $1K+ mixers) probably do not exhibit the same buzz/noise issues that say a $200 mixer has.


Is this the general sentiment - or is there some other aspect of a DJ mixer that causes "non optimal sound - esp on a L1" that I am misunderstanding?
Original Post
I have plugged in everything from an $80 Behringer all the way up to an $8000 Soundcraft Ghost. Just match the levels with your inputs and don't over drive them and everything will work just fine.
Most times I run either 2 separate Peavey DJ boards or a Pro Ramsa DJ/Live sound board. Depend on which head unit I use.
I have some pads I can <tell you about> if you want to continue using "DJ mixers" instead of "non-DJ mixers".

I use a Behringer UB802 and it's clean. No issues.
I have the pads from when I used to use a "DJ mixer"

[Ken-at-Bose removed a reference to selling -- not allowed on this message board -- please see our Terms of Service link at the bottom of every message board page]
Brian:

Ive never had a problem with the mixers I have used.

The mixers I have used
- Pioneer DJM-500
- Rane MLM 92
- Rane MP2

In most cases I have routed the board output through a Rane SM26B (for splitter and mono mixdown reasons) and make sure to set the gain staging across the chain first.

EWong
I guess the SM26B is a "very expensive active pad" Smile

It seems that the overall problem is "too hot" levels out of some "DJ Mixers". Im guessing that these mixers run a higer voltage to "sound louder" and that band mixers stick to the specs for the output levels.
Hi EWong,

quote:
Originally posted by EWong:
I know that the issue has been raised before many times, but a search seems to indicate that the responses (get a band type line mixer - Mackie etc) are buried in responses to other threads. Maybe the issue should be documented and then added to the Wiki?
...


I have a link to this discussion on the DJ page in the Wiki.

I have entitled that section "DJ Mixer vs General Purpose Mixer".

I used this term General Purpose Mixer because the much noted Behringer Xenyx 802 mixer couldn't meet the requirements of any band I can imagine. It has only two microphone inputs, two stereo inputs, and a stereo rca input for CD/Tape. I would consider this a small, general purpose mixer.

Anyway, let me invite you or someone else in the DJ community to write an article

DJ Mixer vs General Purpose Mixer.

You will have to create an account before you can actually input the article. That only takes a few seconds. Please use the same UserName as you use here (e.g. EWong)

If you want to put in the plain text, I can do the formatting for you later.

Thanks for considering this.
ST

Im more than happy to write a contribution.

The biggest problem I have right now is... I have no idea what the "truth" is. I don't want to write an article that basically says "well I read these posts on some forums and formed this conclusion..."

At this stage - by leaving the "content" as a thread Im more comforatable that no one posting here is implicitly claiming that they "know" more than they are stating in their post.

As far as I can tell there are TWO reasons that a "GP" mixer may in fact sound better than a "DJ" mixer.
a) the output signal is "better matched" in terms of voltages and impedence to what the Bose can accept
b) the overall signal chain is "noisy" due to factors involved in the construction of a DJ mixer

If in fact a) is the problem, proper gain staging should IMHO address the issue, no pads necessary (but some operator intelligence may be required - thats a seperate issue in the DJ world)

If the issue is b), then we have to be very careful as to what we MEAN when we say "DJ" mixer or "GP Mixer".

If you are comfortable with me writing an article that is full of assumptions and conjectures - I can do so - but I want it to be labeled as such.... I sure as heck dont know what the root cause of issue is!
Hi EWong,

Thank you!

From the standpoint of community knowledge, I think we need more input from a wider population (more DJs) before we can start drawing conclusions. I am just as happy to keep the link to this discussion in the wiki, and I think it serves us just as well.

Rather than write an article "full of assumptions and conjectures" we can wait until you feel we have sufficient hard information to summarize. Then please go ahead and write the article.
Hi again EWong,

About Pads

quote:
If in fact a) is the problem, proper gain staging should IMHO address the issue, no pads necessary (but some operator intelligence may be required - thats a separate issue in the DJ world)


I agree that you can work with gain staging so that you do NOT clip the Model I (or Classic) Power Stand XLR Channels 1 or 2. That is: Yes — we *can* get sound through the system without clipping distortion at the input without using pads.

However, if you have noise in the system, depending on its source, lowering the output of the source (mixer) may reduce the signal but leave the noise unaffected. So the L1® ends up amplifying a disproportionate amount of noise.

Using a Pad should allow you to leave the output levels on the source (mixer) at their nominal settings with the best signal to noise ratio. Send that down the wire to the Pad (at the L1® end of the wire), where both the noise and the signal are attenuated to an appropriate level before entering the L1®.

How does that fit with your understanding of things?
Thanks for the info ST

I guess the quetion is the signal to noise ratio on the "board" and the impact of increasing the board's output gain.

Also lacking is my understanding of the details concerning the "voltages" and impedences of differnt mixers "line out" signals.

First - what seems to be a problem is not *all* DJ mixers, but "some" DJ mixers.

Second - it appears that part of the "problem" (if one can actually call it that) is that the Bose L1 system has such a flat frequency reproduction that "noise" is "clearer" than it would be in a lesser sound system. (is that a correct statement?)

So if in fact the problem is "noise" in the mixer, the "solution" is a mixer that has a better SNL ratio.

And then the "pad" is just a band-aid fix to the real problem?

Or are their other issues at play - such as if we reduce the signal level of the lesser mixer - the RCA cable itself picks up noise and the L1 promptly amplifies that noise as well?
Hi EWong


quote:
Originally posted by EWong:
Thanks for the info ST

I guess the question is the signal to noise ratio on the "board" and the impact of increasing the board's output gain.


I just got back from a tour of the Mackie and Behringer sites. It seems that when they state specs for Signal To Noise ratios, these are usually done in three states.

  1. All controls down
  2. Channel faders down, Main at 0 dB (or Unity)
  3. Channel faders at 0 dB (or Unity), Main at Main at 0 dB (or Unity)


Mackie



Behringer



What this doesn't tell us in either case, is the effect on the signal to noise ratio as we turn down the main mix.

My speculative view is that almost all systems (one or more components strung together) have some self-noise. Some of that will be present no matter what we do, as long as the system is functioning. Some of that will be relatively fixed (e.g. that hiss that just won't go away), and some will be variable (that hum that rises and falls as you turn up the gain somewhere in the system). And then there is the signal that we want to hear.

Aha - that's how to explain it.

If you have experienced "that hiss that just won't go away", but noticed that if you turn up the volume, the real music seems to overcome the hiss and we don't hear it any more then maybe we can talk about the effect of turning down the output of the mixer.

If you have noise in the system up to and including the mixer, and it is of the kind that seems less troublesome as you turn up the volume, then it is really important to get an optimal match between the output levels and the L1® input levels. Optimal is - having the mixer running at the best position on the main output to have lots of good sound (signal) masking the bad sound (noise). I have found this is is usually when the mixer main output is at 0 dB (Unity).

If the overall level is too high for a good match with the input section of the L1® then we have to attenuate the signal somehow. If we do it with the main output of the mixer, we may be reducing the signal, but the noise remains. Just like turning down the volume in a noisy system. The music is lower but the noise becomes more apparent.

If we leave the mixer at its optimal settings but attenuate the signal with a pad just before it enters the L1® we stand a better chance of lowering the noise as well as the signal. This includes any noise we picked up between the mixer and the L1®.

I don't hold out that this absolutely correct, but it lines up with my general experiences wiring up gear.


edit - grammar
ST

That was a VERY helpful bit.

The reason a pad works is that the hot signal - while too hot for the L1, does allow a larger Signal to Noise seperation than a low signal will.

So we attenuate / pad the signal at the L1


But I was off on a slighly differnt tack.

The question is WHY did the "DJ vs GP" issue even come up?

My GUESS was that DJ mixers have to send the signal through
a) sliders not rotary pots
b) an extra potentiometer (i.e. the cross fader).

I am very sure but can prove, that "budget" rotary potentiometers have less noise than "budget" slider potnetiometers. In paricular since its easier to seal a rotary potentiometer from the elements than it is to seal a sliding potentiometer.

There are ways to address the problem (using the potentiometer to set the voltage on a VCA op amp - thus removing the signal path from the slider potentiometer) but these all add expense and are thus less likely to be seen on "budget" equipment.

There have been claims that even high end (i.e. $800+ Pioneer?) mixers are just a noisy as lower price point ($200 B or N or A brand mixers), but I personally dont believe it (I have a Pioneer DJM-500).

And as professional studio boards have shown - there is a way to make a low noise slider pot.
DJ mixers that use a cross fader have to send the signal though BOTH the channel level slider AND the cross fader slider.

As I point out in another post - slider pots for a given price point are IMHO noiser than rotary pots at the same price point.

Also - the cross fader does TWO things - turn one thing up and another down.
I have NO idea how one is wired - maybe its the middle resister in an H pad? If so - that would exlplain ALOT about why budget DJ mixers are noisy

On the DJM-500 - I BYPASS the cross fader... maybe thats why I dont notice a noise problem?
quote:
Originally posted by EWong:
Brian:

Ive never had a problem with the mixers I have used.

The mixers I have used
- Pioneer DJM-500
- Rane MLM 92
- Rane MP2

In most cases I have routed the board output through a Rane SM26B (for splitter and mono mixdown reasons) and make sure to set the gain staging across the chain first.

EWong
I guess the SM26B is a "very expensive active pad" Smile

It seems that the overall problem is "too hot" levels out of some "DJ Mixers". Im guessing that these mixers run a higer voltage to "sound louder" and that band mixers stick to the specs for the output levels.
Ewong, I never had problems with any of my dj or band mixers I've hooked up to the l1. I just felt the sound would be better if I used something that the l1 inputs liked or matched too. Going from a dj mixer to a band type mixer made a big difference. Going from a band type mixer to the t1 was 100% better. I had good sound before now I have unbelievable sound. You should try one and see what you're missing. Any dj should. Do not hook it to another mixer it would defeat the purpose of the t1.

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