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Mackie 1202VLZ4 suffering from loss of balance
Old 9th June 2020
  #1
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Mackie 1202VLZ4 suffering from loss of balance

Hey, I wonder if anybody has come across this.

I just got a new Mackie 1202VLZ4 and it seems to have quite a problem with balance.

From any input 1-12 and stereo returns with the same signal (-3db 120Hz sine) always returns an output which is exactly 1.7db lower on LEFT

Headphone, stereo send, master, control room, alt and the VU too

I have checked the outputs from my Delta 1010 soundcards, all perfect.

Doesn't matter where you put the signal, the output from everywhere is wrong. I tested a variety of frequencies, all the same.

I know, everybody will say; it's new send it back. However, I am concerned that this might be a "standard thing", spend a week waiting for a new one - just to have the same problem.

I did have a look at the circuit diagrams but couldn't see anything common between every input and every output (apart from the power supply).

Any ideas

Last edited by LincolnG; 9th June 2020 at 09:23 PM.. Reason: error
Old 9th June 2020
  #2

Sounds like an issue with the left summing amp... Send it back, unless you see this more as a learning opportunity than a tool for music.




-tINY

Old 9th June 2020
  #3
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Easily said, but have you ever had one of these on the bench?
Old 9th June 2020
  #4

I haven't had a Mackie opened up since the "VLZ" didn't have a number after it....

I have a 802 VLZ3, but it was running fine last time I used it.




-tINY

Old 10th June 2020
  #5
I recently bought a brand new 1202VLZ4 and this unit is having the exact same problem. Going to send it back to the shop.
Old 10th June 2020
  #6
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Quote:
Originally Posted by Wootson View Post
I recently bought a brand new 1202VLZ4 and this unit is having the exact same problem. Going to send it back to the shop.
Yes, I'm considering the same. It's a shame though, damn fine mixer. The versatility is unmatched for its routing options - today that is! And the sound is very good!

I need something to replace my old Soundcraft Compact10, which I have battled on with for years because I couldn't find anything to replace it.

At the moment I have patched the soundcard router software to correct for the difference. This has fixed the problem from the PC and DAW although live recording will still be an issue.

Can I suggest that you send an email with the serial number to Mackie, as their UK support seems to be completely unaware of the issue. [email protected] if you're in the UK.

I would love any other suggestions to replace my Compact10, perhaps I'll start a new thread.
Old 10th June 2020
  #7

At least it's consistent... I bet they had a mishap on the line and the pick-and-place machine was loading the wrong resistor somewhere.



-tINY

Old 11th June 2020
  #8
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Quote:
Originally Posted by tINY View Post

At least it's consistent... I bet they had a mishap on the line and the pick-and-place machine was loading the wrong resistor somewhere.



-tINY

I had the same thought, probably easily fixed. Except, the fact that it effects all inputs to all outputs.

The ALT output uses a different amp and routes directly to the ALT output. However it has the same error.

Could the "error" have happened mutiple times?

Or could the balance control have the center click (or track) in the wrong place, I have read a few people complaining about the quality of the pots.

Anybody want to look at the circuit diagram and make a guess where the error(s) might be ?
Old 11th June 2020
  #9
Quote:
Originally Posted by LincolnG View Post
I had the same thought, probably easily fixed. Except, the fact that it effects all inputs to all outputs.

The ALT output uses a different amp and routes directly to the ALT output. However it has the same error.

Could the "error" have happened mutiple times?

Or could the balance control have the center click (or track) in the wrong place, I have read a few people complaining about the quality of the pots.

Anybody want to look at the circuit diagram and make a guess where the error(s) might be ?

Well, on a budget unit, they may well have used the same summing amp and added a (cheaper) buffer for the Alt output....

I'm curious now - as it could be a batch of bad pan pots.



-tINY

Old 11th June 2020
  #10
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Rick Dalton's Avatar
Quote:
Originally Posted by LincolnG View Post
Hey, I wonder if anybody has come across this.

I just got a new Mackie 1202VLZ4 and it seems to have quite a problem with balance.

From any input 1-12 and stereo returns with the same signal (-3db 120Hz sine) always returns an output which is exactly 1.7db lower on LEFT

Headphone, stereo send, master, control room, alt and the VU too

I have checked the outputs from my Delta 1010 soundcards, all perfect.

Doesn't matter where you put the signal, the output from everywhere is wrong. I tested a variety of frequencies, all the same.

I know, everybody will say; it's new send it back. However, I am concerned that this might be a "standard thing", spend a week waiting for a new one - just to have the same problem.

I did have a look at the circuit diagrams but couldn't see anything common between every input and every output (apart from the power supply).

Any ideas
Found this on page 19 owners manual. Just thought it interesting.

"PAN controls employ a de-sign called “Constant Loudness.” It has nothing to do with living next to a freeway. As you turn the PAN knob from left to right (thereby causing the sound to move from the left to the center to the right), the sound will appear to remain at the same volume (or loudness). If you have a channel panned hard left (or right) and reading 0dB, it must dip down about 4dB on the left (or right) when panned center. To do otherwise (the way Brand X com-pact mixers do) would make the sound appear much louder when panned center."
Old 11th June 2020
  #11
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Quote:
Originally Posted by tINY View Post

Well, on a budget unit, they may well have used the same summing amp and added a (cheaper) buffer for the Alt output....

I'm curious now - as it could be a batch of bad pan pots.



-tINY

Well, that might me just right.

But, I intend to prove it. At the weekend I'll throw all caution to the wind and have it apart. As the fault appears on all channels it should be easy to observe. I intend to look at stereo channel 5-6 with the scope, at the same time I will check the values of the main gain amp's input and feedback resistors to check their values. R901, 935 - 36K and R917,947 2K. At least at this point I will be able to indentify if the pot (R926) is bad, the resistor values are wrong or even if there is something else going on.

I have sent an Email to Mackie, but so far they have failed to respond.
Old 12th June 2020
  #12
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Quote:
Originally Posted by Rick Dalton View Post
Found this on page 19 owners manual. Just thought it interesting.

"PAN controls employ a de-sign called “Constant Loudness.” It has nothing to do with living next to a freeway. As you turn the PAN knob from left to right (thereby causing the sound to move from the left to the center to the right), the sound will appear to remain at the same volume (or loudness). If you have a channel panned hard left (or right) and reading 0dB, it must dip down about 4dB on the left (or right) when panned center. To do otherwise (the way Brand X com-pact mixers do) would make the sound appear much louder when panned center."
Yeah, I read that too. I did look on the circuit to see if there was any evidence for some amazing bit of circuitry to pull off this wizardry which would require some sort of voltage controlled attenuator possibly with some computer-trickery.

That doesn't happen here. The tone amp feeds directly into a NJM4560 op. amp with a max gain of 20 (controlled by the LEVEL pot.) then directly to the BALANCE pot which feeds another NJM4560 op. amp, gain 10 via a 5k1 resistor and the ALT, MAIN switch network.

My guess, this is simply done using a double log. pot. on the balance control. Generally here a linear pot. would be used, or a stereo single log. pot. in a better mixer.

Some mixers do use voltage controlled attenuators, the Pioneer DJMs for example. However, it is quite complicated to do and therefore expensive.

In this case I'm afraid the bit in the manual is just sales techno speak for we paid 10cents more for our balance pots.

However, your observation is important. I already believe a batch of "not exactly perfect" pots might be to blame. If that's true then simply off-setting the balance on each channel is a sue-doe easy fix, or an extra resistor to drop the RIGHT channel 1.7db to match the left.
Old 12th June 2020
  #13
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Rick Dalton's Avatar
Quote:
Originally Posted by LincolnG View Post
Yeah, I read that too. I did look on the circuit to see if there was any evidence for some amazing bit of circuitry to pull off this wizardry which would require some sort of voltage controlled attenuator possibly with some computer-trickery.

That doesn't happen here. The tone amp feeds directly into a NJM4560 op. amp with a max gain of 20 (controlled by the LEVEL pot.) then directly to the BALANCE pot which feeds another NJM4560 op. amp, gain 10 via a 5k1 resistor and the ALT, MAIN switch network.

My guess, this is simply done using a double log. pot. on the balance control. Generally here a linear pot. would be used, or a stereo single log. pot. in a better mixer.

Some mixers do use voltage controlled attenuators, the Pioneer DJMs for example. However, it is quite complicated to do and therefore expensive.

In this case I'm afraid the bit in the manual is just sales techno speak for we paid 10cents more for our balance pots.

However, your observation is important. I already believe a batch of "not exactly perfect" pots might be to blame. If that's true then simply off-setting the balance on each channel is a sue-doe easy fix, or an extra resistor to drop the RIGHT channel 1.7db to match the left.
I wasn't going to post that, as everyone would say (Thats How Mixer Works DumbAzz.)
Normally (thats a good word too use here) its the cheap and or dirty TRS jacks on the Mackie, as in an Mackie SR24.4 VLZ Pro, I just Fixed? so to say (dirty TRS jacks) Theirs an Mackie SR 32.4 VLZ Pro, thats been holding one of my shop walls up for a couple years now, it had TRS jack issue, but also has an OpAmp out, alot of knobs, (My excuse) Really more like, every time I go to work on it, I have to go through my studio, and I find myself, Hours later still playing guitar or the likes. LincolnG, sounds like you know what you're doing, so good luck there.
Old 12th June 2020
  #14
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Quote:
Originally Posted by Rick Dalton View Post
I wasn't going to post that, as everyone would say (Thats How Mixer Works DumbAzz.)
Normally (thats a good word too use here) its the cheap and or dirty TRS jacks on the Mackie, as in an Mackie SR24.4 VLZ Pro, I just Fixed? so to say (dirty TRS jacks) Theirs an Mackie SR 32.4 VLZ Pro, thats been holding one of my shop walls up for a couple years now, it had TRS jack issue, but also has an OpAmp out, alot of knobs, (My excuse) Really more like, every time I go to work on it, I have to go through my studio, and I find myself, Hours later still playing guitar or the likes. LincolnG, sounds like you know what you're doing, so good luck there.
Do I know what I'm talking about ? Yes. But as they say, talk is cheap. It's one thing knowing what might be going on another altogeher trying to fix it on a super small high density board like this.

My aim at this point is to "try" to prove the point and know my new mixer better than Mackie CS appears to / or cares about.

The truth is that I really like this little mixer. The sound is SOooo much better than my old Soundcraft and although I'm going to have to get some other stuff to get it working the same, well hey ho.

What I don't like is that Mackie must know that there is a problem and yet they simply just don't comment. It's like, if you can find the faults then maybe this mixer isn't for you - I find that very dishonest, and not the level of service that most musicians expect from one of their favourite brands.

Just answer my messages admit the pan pots have a problem and then I'll simply offset them or add some resistors somewhere - it's just not that difficault. We are all professionals, we know what to expect and what to do!
Old 18th June 2020
  #15
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Finally an answer from Mackie

After not hearing anything useful from Mackie EU (Polar) I sent a message through to Mackie corportate in the USA. My message read:

"If I inject a mono signal the output always favours the right-hand channel.

Using a signal generator to inject on 1,2,3,4,5,7,9, & 11 (-3db, 500Hz Sine, L=2.78v R=2.78v RMS)

TRS Main, unbalanced reads L=1.9v R=2.3v RMS

Please can you confirm if this is a “fault” or if it is expected. "


Mackie responded:

"Hi Lincoln,

Thanks for reaching out!

All 1202VLZ4 & 1402VLZ4 units exhibit this behavior. I’m not sure exactly why the output isn’t perfectly even on both sides, but we have confirmed that it is normal for these units.

Thanks,

Cramer
Technical Support Level 2"
Old 18th June 2020
  #16
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Quote:
Originally Posted by LincolnG View Post
After not hearing anything useful from Mackie EU (Polar) I sent a message through to Mackie corportate in the USA. My message read:

"If I inject a mono signal the output always favours the right-hand channel.

Using a signal generator to inject on 1,2,3,4,5,7,9, & 11 (-3db, 500Hz Sine, L=2.78v R=2.78v RMS)

TRS Main, unbalanced reads L=1.9v R=2.3v RMS

Please can you confirm if this is a “fault” or if it is expected. "


Mackie responded:

"Hi Lincoln,

Thanks for reaching out!

All 1202VLZ4 & 1402VLZ4 units exhibit this behavior. I’m not sure exactly why the output isn’t perfectly even on both sides, but we have confirmed that it is normal for these units.

Thanks,

Cramer
Technical Support Level 2"
To say that I was surprised is an understatement !!!!
Old 18th June 2020
  #17

Wow. I'd like to talk to a couple design engineers over there - or get the schematic and layout files....



-tINY

Old 18th June 2020
  #18
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Rick Dalton's Avatar
Quote:
Originally Posted by LincolnG View Post
After not hearing anything useful from Mackie EU (Polar) I sent a message through to Mackie corportate in the USA. My message read:

"If I inject a mono signal the output always favours the right-hand channel.

Using a signal generator to inject on 1,2,3,4,5,7,9, & 11 (-3db, 500Hz Sine, L=2.78v R=2.78v RMS)

TRS Main, unbalanced reads L=1.9v R=2.3v RMS

Please can you confirm if this is a “fault” or if it is expected. "


Mackie responded:

"Hi Lincoln,

Thanks for reaching out!

All 1202VLZ4 & 1402VLZ4 units exhibit this behavior. I’m not sure exactly why the output isn’t perfectly even on both sides, but we have confirmed that it is normal for these units.

Thanks,

Cramer
Technical Support Level 2"
So they're saying it's normal (because they cant figure it out) Flat out saying it's not normal but were making exceptions with the 1202VLZ4 & 1402VLZ4 units.
Old 18th June 2020
  #19
This is surely not normal behavior for any audio gear whatsoever. I never heard of any other mixer that favors the right channel in terms of audio volume. And it isn't even possible to adjust the left and right volume on these mixers, as the main pot is just a stereo volume control. So you always need to alter the recording with software afterwards, or place another panning control box after the mixer. To me this mixer was unusable, as I only do DAWless music making these days and everything is recorded live in one take. I just want to press record and don't want to worry about making up for obvious hardware design flaws. I really wanted to like the Mackie, but I now have a Yamaha MG12.
Old 19th June 2020
  #20
Quote:
Originally Posted by Wootson View Post
To me this mixer was unusable, as I only do DAWless music making these days and everything is recorded live in one take. I just want to press record and don't want to worry about making up for obvious hardware design flaws.

Well, I get that it bugs you. But, the fix is pretty easy at the recording device for the 2-track...

I never even considered using these as recording boards - they're dandy for a couple of vocal mics and maybe a keyboard at a performance, though.




-tINY

Old 19th June 2020
  #21
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Radardoug's Avatar
 

Quote:
Originally Posted by Wootson View Post
This is surely not normal behavior for any audio gear whatsoever. I never heard of any other mixer that favors the right channel in terms of audio volume. And it isn't even possible to adjust the left and right volume on these mixers, as the main pot is just a stereo volume control. So you always need to alter the recording with software afterwards, or place another panning control box after the mixer. To me this mixer was unusable, as I only do DAWless music making these days and everything is recorded live in one take. I just want to press record and don't want to worry about making up for obvious hardware design flaws. I really wanted to like the Mackie, but I now have a Yamaha MG12.
Its a 1.7 dB error, not the end of the world. Put an adjustable pad in the high channel, set it to 1.7 dB loss, problem solved.
Old 19th June 2020
  #22
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what a piece of sh..!

in principal, i though many of their desks up until onyx were fine (i then lost track) but frankly, they have far too many quirks such as no inserts on groups, vastly different ouput levels on direct out, auxes, groups and mains, filter center frequency nowhere near where they'd be useful etc. so i gave up using them even for the most simple tasks,
except for two older desks which refuse to stop working and which are in a long-time rental - or maybe these clients have long ditched the desks?! couldn't even blame them...
Old 19th June 2020
  #23
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Quote:
Originally Posted by tINY View Post

Wow. I'd like to talk to a couple design engineers over there - or get the schematic and layout files....



-tINY

I have the full service manual if you want to take a look
Attached Files
Old 19th June 2020
  #24
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Quote:
Originally Posted by Wootson View Post
This is surely not normal behavior for any audio gear whatsoever. I never heard of any other mixer that favors the right channel in terms of audio volume. And it isn't even possible to adjust the left and right volume on these mixers, as the main pot is just a stereo volume control. So you always need to alter the recording with software afterwards, or place another panning control box after the mixer. To me this mixer was unusable, as I only do DAWless music making these days and everything is recorded live in one take. I just want to press record and don't want to worry about making up for obvious hardware design flaws. I really wanted to like the Mackie, but I now have a Yamaha MG12.
To make matters worse, the error grows the higher you put the master control. I'm hoping with the help of others we'll be able to find where the error is and fix it.
Old 19th June 2020
  #25
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Quote:
Originally Posted by tINY View Post

Well, I get that it bugs you. But, the fix is pretty easy at the recording device for the 2-track...

I never even considered using these as recording boards - they're dandy for a couple of vocal mics and maybe a keyboard at a performance, though.




-tINY

Actually it is not at all easy. EG. mono in should always equal 1+1 not 1+1.2 or ZERO in opposition, that'll never work

Some inputs to the DAW will be fair and square, but these won't.

I suppose I could always just put additional pots on the outputs to ZERO them
Old 19th June 2020
  #26
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Quote:
Originally Posted by Radardoug View Post
Its a 1.7 dB error, not the end of the world. Put an adjustable pad in the high channel, set it to 1.7 dB loss, problem solved.
Sure that I could do, but I hate adding anything extra into the signal path. The noise floor on modern electronic music has to be really clean and each addition messes with the cleanlyness.
Old 19th June 2020
  #27
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Quote:
Originally Posted by deedeeyeah View Post
what a piece of sh..!

in principal, i though many of their desks up until onyx were fine (i then lost track) but frankly, they have far too many quirks such as no inserts on groups, vastly different ouput levels on direct out, auxes, groups and mains, filter center frequency nowhere near where they'd be useful etc. so i gave up using them even for the most simple tasks,
except for two older desks which refuse to stop working and which are in a long-time rental - or maybe these clients have long ditched the desks?! couldn't even blame them...
However, believe it or not there actually isn't much choice in the small recording market. The Midas looks great, but sounds like a iPhone. The Soundcrafts are not that much better.

This mixer sound the part and does mostly. If only I could get this damn level error resolved.
Old 19th June 2020
  #28
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Here is a copy of the Service Manual if anybody wants to help me get to the bottom of this.
Attached Files
Old 19th June 2020
  #29
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Quote:
Originally Posted by Rick Dalton View Post
So they're saying it's normal (because they cant figure it out) Flat out saying it's not normal but were making exceptions with the 1202VLZ4 & 1402VLZ4 units.
Also, it is not even a small offset.

I have a few "theories" as to what has happened. For example, they have stuck the aux sends on just the left channel and it pulls it down, or there is a wrong resistor somewhere.

I would really love somebody else to have a look at the circuit and help me find where to either replace the incorrect component or in an interstage link replace it for a resistor to bring the right down to the same as the left. Which I'm amazed Mackie did already do !!!

Last edited by LincolnG; 19th June 2020 at 08:37 PM.. Reason: my terrible spelling
Old 19th June 2020
  #30
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Radardoug's Avatar
 

The circuit as drawn looks fine and should be symetrical. Possibilities are:
There is a problem with the pan pots and the two tracks dont match.
The pick and place machine was programmed with the wrong parts and fitted an incorrect part.
To find out the answer you will need to do some detective work. Quickest and easiest, with the pan pot centred, measure the resistance from the pan pot centre to ground on each side. If there is a significant imbalance, your problem is there. If not, then its probably the pick and place problem.
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