Zero 8 modifications and optimizations

[Okkie]

Yes, I am one of those many Zero 8 users who experienced several issues with my Zero 8. Of course mine occured mainly after warranty period was over, so I had to decide what to do: send it for repair, replace it by something new or... as an engineer... have a look at it's issues myself...

In this little topic I will try to address a few issues which can be found in this forum more often. The issues that I've been able to fix were the following ones:

1. inadequate Firewire behaviour
2. Poor Analog VU meter response
3. Defective Headphone output
4. Malfunctioning Y/axis of the KAOS pad.

In order to get these things fixed - improved, a reasonable experience with electronics is advised, so if you´re not sure, don´t even start! At least don´t hold me responsible for anything .

Inadequate firweire behaviour
When running Ableton or Traktor, generally I suffered from seriously bad behaviour of the firewire interface regularly. As so many other people I have been looking for the fix within Windows and PC hardware. For Example I did several clean installs of Win7-64 bit, installed Texas Instruments Firewire card, etc. Nothing helped!

I was very close to simply throw the Z8 in the corner since the so often named driver errors seemed not to be solvable. I couldn't however give up, especially since there obviously have been number of people with a satisfying performance with a same setup.

It was actually a friend of mine who advised me to simply try and put mechanical pressure on the unit. During a seriously distorted audiostream over the firewire port, I simply smashed the unit and... All distorsion dissapeared ?!?

OK, a mechanical issue in the unit then, can be quite complicated. I decided to take the unit apart and investigate. The whole Firewire handling is been done in a separate closed unit within the Zero 8, right behind the Firewire connections on the backplane. It took some time to get the unit out and investigate it. From the principle it looked fine but I decided to give the whole PCB some maintenance with my SMD soldering heater in order to make sure that everything that probably wasn't ok, would be. In addition I have seen that the flatcable towards the processor PCB wasn't plugged in 100% properly.

To me this solved all my crappy s**t with regards to Firewire behaviour, all is fine since then (about the last 5 months). I really enjoy it now!

Analog VU meter response
So most of us have experienced that the VU meter response is rather low. Of course the first thing to do is make sure that the headroom of the mixer is utilized to a reasonable extend. What I did is simply trim the (analog) inputs to +6dB (setup > system > input trim) and then keep the gain knobs simpy in it's central position. This works fine in order to minimize noise behaviour (although I think it isn't bad in it's factory settings anyway). In such case you will logically see that the channel fader''s VU reaches it's orange bar dot, but I couldn't measure any increase of distorsion when applying my Rohde & Schwarz Audio Analyzer UPV (THD fully analog in this case is <0.08% @ 20kHz bandwidth, rather good for a mixer).

So, in this case, the analog meters still only just start to move, and never cross -10dB on the scale. I personally do not see a big importance in these meters, other then noticing if there is any audio or not, and I'm not really interested to have an accurate reading other then "oversteering indication`.

In order to improve this, I simply removed the white cover at the right upper corner of the mixer which gave me access to the trimmers for these meters. Keeping in mind it´s settings as I have mentioned above, I have applied 0dBV to one of its inputs with the corresponding fader full open. With this setting I have adjusted the trimmers to an exact 0dB reading on both meters. In my case I had to adjust the trimmers until about 90% of it´s maximum instead of its original )about' 40% setting.

Now that´s much better. Finally I can see something happening when looking at these meters. Corresponding to this, I see the overload indicators light up nicely in line with a reading of about ~2dB reading, which is fine by me.

So, if you prefer to have a similar behaviour, simply stick to adjusting the input trim and change the VU meter trimmers to about 90% of maximum settings and you'll be fine.

Defective headphone output and KAOS pad
More people seem to have these issues. It runs a bit to far to explain here how to replace the amplifier chip on the control PCB, (close to the headphone plug), but at least I figured a possible cause that both influences the headphone amp as well as KAOS pad problems.

I already noticed before that the Zero 8 produces quite a bit of heath, especially on the right side of the mixer. I easily found that this is caused by the Switched mode Power supply which is right underneath the control assembly on the right side of the unit. I measured the temperature of the main heatsink and experienced that this easily reaches 95 degrees Celsius ! That's seriously hot and I am convinced that this regular temperature clearly decreases the lifetime of the mixer and some of it's components.

This has definitely been the case with the headphone AMP and is probably the cause for the KAOS pad defects as well. As I have seen that many people have this issue, it obviously is bad designing from KORG, not taking temperature increase into account enough.

So what dit I do to solve it? Few things:

-Replace the LM chip for a properly working headphone output again
-re-solder the lug of the yellow/brown cable which connects the KAOS pad to the main controlboard. I tested whether the KAOS pad manually before with a simple Ohm meter, since this pad is not much more then a variable resistor matrix with an X and Y lead, rather easy to check (soldering four wires from the connector to a simple multimeter will do and then do a practical test with your finger on the KAOS pad to check behaviour).

Well, re-soldering the connectors solved my KAOS pad problems for once and for all. I clearly can imagine that the aging process of the solder was significantly multiplied by a high factor due to the extreme temperature development right underneath by the power supply. It's a miracle that mine was still working anyway.

So, now what to do about the temperature development ? Well, I made quite a few considerations before I finally decided to install a little fan between the power supply and the main control board. There is some nice space there where a 4x4cm fan fit's in easily. I decided to apply a brushless ultra quiet fan which runs instead of at the normal 12V only at 5V, so can't be heard in that case, excellent.

To make it even more silent, I have decided to "glue" the fan on a piece of antistatic foam, preventing resonance trough the Zero 8. I really can say it is a satisfying result. Temperature doesn't exceed 35 degrees anymore and the unit runs really stable.

By the way, I took the 5V directly from the second pin from the right of the Power supply output agains the Zero 8 chassis. That's it and that's that

So, quite a bit of text, but I hope I can help a lot of dissatisfied Zero 8 users to get their unit up and running the way it should. Of course the behaviour is caused by design limitations and support by KORG, but if you ask me, some rework on this magnificent mixer (it still offers the best features available in the market from my point of view) would have made this into a really succesful product...

Best Regards,

Mischa - AKA 'OKZ...

[bitcrusher213]

Hey Okkie or a Korg TECH person!

Reply when you can, I have a ZERO 8, it works great!!

-I don't hear a hiss, regardless ill try the SPDIF trick most are doing to see the difference,
- my firewire works fine
- i'm ok with the low UV meter intended for DIGITAL reads, because i'm using all 8 channels effectively so it moves..
- X/Y pad works fine.
- props to you for installing a fan! i'm ok with the heat, but I see your points.

I have a question about channels 3, and 4, the A/B led lights for both,
they go orange in the Audio/MIDI mode/other modes, but in just MIDI mode, they both don't light up blue, they just remain dark, I see in other video tutorials (unware of what ver. firmwares they had) on the net that both channels 3/4 the a/b buttons go blue like the rest of the A/B buttons do on the other channels. Anything I can do to make sure they go blue? Do you think this might be a firmware problem with the 1.6 upgrade which is the version I have. This was serviced before by Korg techs long ago, I just noticed this now though.

The functions of the A/B works..for the crossfader, just not the blue leds.

Is yours the same too? or what do you suggest? If this is a simple fix, I could do it myself.. i'm ok with delicate electronics. Worst case, disconnected led lights or poorly soldered wires? Would this be an easy fix if that was the case? Since you modified yours I figured I post to your topic. ) Let me know someone!


-side question, is there a way to turn the ZERO 8's x/y screen into a Blue LED screen/other parts instead of its stock white led screen? I know people have modded their kp3s with still images, and things like that, and used some kind of black screen, "google MISA guitar"

[jose b]

Great post thanks

[dam75]

Concerning the levels and noise floor, I have no issues, same thing for the metering and headphone level.

I use it a lot with traktor and the firewire connection.

To use it with the appropriate line level, you have to drive it to clipping then decrease the level a bit to have some headroom. forget the knob click at the center position.

A very convenient tool to see when clipping is to turn the gain trim all the way up so that the orange gain ring led flashes red. then, decrease the gain level.
They don't talk about this "flash" feature in the manual, but it's very handy.
If you don't reach the red light, it means your level is very ok.

with those levels (around -0dBfs) the master level meters needles move properly and accurately.

I think the general mistake with this mixing desk is to think that the gain trimmer is set to 0dB gain at 12 o'clock. but usually with firewire sending 0dBFs white noise, you have to turn it to 4 to 5 o'clock to overload the input.

I usually turn the gain pot to 3 o'clock as a default value to get good levels.

If you mix 2 or more tracks you'll see your master output meter level easily reach the 0dBvu in the center position, this is what this mixer is meant for.
If you need more master output levels, turn up the master knob to about 3 o'clock, you will easily reach the mixer overload this way, and it sounds pretty hot like this around +0dBvu.

this way :
- Nice and accurate master metering
- signal/noise ratio is better
- sound level in the headphone is louder because the input stages are better driven.

So, don't forget, with the zero8 : Crank up the input gain knob.


EDIT: I made a video to show when the input ring light flashes once clipping.

http://youtu.be/64G3knlsisE

hope it helps.

<iframe width="560" height="315" src="http://www.youtube.com/embed/64G3knlsisE" frameborder="0"></iframe>

[intricate]

Good advice dam75!!!

[infindebula]

Such an informative video. Thank you so much.

Just wondering ... what is the LED meter beside the channel input doing when you set your gain that hot? Is it going into the red?

Also, did you set "pre-gain"?

I just found this document (which I most certainly did not get with my mixer) at http://www.korg.com/uploads/Support/ZER ... 370000.pdf (but I pasted the text in below):

THANK YOU for purchasing your Korg ZERO8.  Being a digital  mixer, it is especially important to observe proper gain staging  throughout the signal path to achieve optimal sound quality. To help you we offer the following suggestions. 

The ZERO8 is designed to be able to accept a very strong signal on input, so be sure to take full advantage of this high ceiling for each channel: 

1. Set the Master and Booth volumes to “0” (Otherwise you might overload your speakers. We will address the output stage next) 
2. Select an input source for the channel you’re feeding signal to and begin playing audio. Your source should be at maximum volume 
3. Press the SETUP button to access the main menu 
4. Touch “System” on the screen 
5. Touch “Input Trim”* on the screen 
6. Using the corresponding knob above the screen, adjust the INPUT TRIM for the input type you’re using, to best accommodate the level of your sound source. If the meter on the channel indicates clipping (The last, red LED on the meter lights up), step down until you reach as close to unity gain as possible (The second to last, orange LED on the meter) 
7. For fine gain adjustments, use the gain knob at the top of the channel. If the LED under the gain knob starts to blink (clipping) lower the gain just below that point 
8. Repeat this process for all connected sound sources 

*If you do not see an Input Trim choice, please refer to www.korg.com/ZERO8 for the latest operating system upgrade, which provides this feature, in addition to other improvements. 

Master and Booth Outputs – The best signal-to-noise ratio and hottest possible FireWire audio signal will occur by setting the Master 
Volume to maximum and then attenuating the speakers/amplifier to reach the desired listening volume:

1. Start with your speakers/amp at the lowest possible setting/level 
2. Set the Master output on the mixer to maximum 
3. Slowly bring your speakers/amp up to the ideal listening level 

If you require more volume control over your monitors in a studio environment, use the Booth output for your monitors and leave the 
Master at maximum.  

Outputs/master level select on ZERO8 – Understanding the output levels and types of cables that are meant to address those levels will 
assure the best possible signal level: 

‐ Master XLR outputs at +4dB  
‐ Master ¼” outputs at +4dB or ‐10dB, selectable via a switch over the inputs – Use balanced (Tip/Ring/Sleeve or “TRS”) cables in 
conjunction with the +4dB selection and unbalanced (Tip/Sleeve or “Instrument”) cables in conjunction with the ‐10dB selection 
to assure optimal signal 
‐ Booth ¼” outputs at +4db or ‐10dB, accepts balanced and unbalanced cables and self‐switches dB levels based on the type of 
cables you use 
 
We hope you enjoy your ZERO Mixer!  
If you have any questions on setup, please contact your local Korg Support center. A listing is available at 
http://www.korg.co.jp/English/Distributors/.