Ever seen inside a Korg Zero4?

Took apart my Z4 today, mainly out of curiosity but also to examine the headphone amp section. Here are some pics I took. This thing had a ridiculous number of screws, multiple boards, and all sorts of weird loose parts.

Bottom half of the mixer. You can see the power supply as well.



Top board. Screws galore and I had to pull off every single knob to separate it from the top plate.


All of these...yeesh.


Headphone section. See the opamp? I'm reading up and working with a friend to see what can be done about modifying this area for more volume.


Mic and guitar input board.


Underside of the top board.


Headphone section...I thought I could put something inline here but it really is just some sort of splitter dealie.


While the thing was apart, I noticed/learned a few things:
- There isn't a whole lot of room in this mixer. Not much at all. And with boards top and bottom, height is also very limited inside this mixer.
- Woe be the man who wants to take this mixer apart and replace all the damned LEDs. All surface-mounted, they look like 0805 or 0603. Stupid tiny.
- If you unplug the little ribbon cable plug situated behind the EQ Selector knob up front and reassemble the mixer but neglect to plug that one bit back in, most functions will work but the EQ knobs on all 4 channels function as weird LP and HP filters. Also no need to panic and fully disassemble the damned thing all over again to troubleshoot this; just the front panel needs to come off.
- Fiancees don't like when you start taking apart a mixer when they leave at 5pm and dinner isn't ready when they get home at 8, and they find you still putting the thing back together.
- 3M Di-Noc carbon fiber wrap looks great on the side pieces, and helps keep the mixer from marring the finish on custom turntables placed next to it.

See what happens when I'm not working on a deck? I'm pretty sure I've got a problem. I need a support group. Or more decks to mod.

 

With the NE5532 (assumning this is the one) you wouldn't be able to get much power unless you replace it with a dual Power Amp or add some BJT at the output. If you just play with the gain resistor you may have more gain, but also end up in just more distortion in case it's already maxed out for max gain. Any decent scope will tell (ears 'course).

Not sure if there's any drop in replacement for the NE5532 as Power Amp (I'll have a look at ST, Ti, National, Analog and Linear website for that.), but sure easy enough to modify.

 

Would be much appreciated DJKeyWee, and thanks for the response. I'm very much new to this and I'm learning as I go. Yes, it'll wreck my setup, but for some reason I'm taking the risk.

 

Closest match for the NE5532 could be a LM4880, but must work bellow 5V and use a single rail supply, Specs aren't that bad considering a SOIC chip, but still not that loud, obviously higher than the 80mW listed in the Zero 4 specs.

Knowing that, you'll end up with all sort of jumpers here and there in a smal pcb area... nothing really interesting in the end. I would opt for an external amp. Easy to have in 8 pin dip is LM386N, whose provide some decent result, doesn't cost a lot, available almost everywhere, and work with large psu range.

Just found that schematic that should work fine.
http://electronics-diy.com/electronic_schematic.php?id=665
HeadBanger

This should fit inside your mixer

 

Zowie! The headbanger looks like it might fit the bill. Now to work out how to mount, power, and connect it. I already have a headphone amp/splitter, but would prefer to just pack up and bring out the minimum number of boxes at gigs.

 

Looking at the datasheet right now and I see the gain should be set to 20, and the guy implemented a bass boost in it. Tomorrow I'll try it myself just to satisfy my curiosity. If you have any issue, let me know, I have everything here to test and modify it in case you need more gain or whatever else.

Kinda Canadian TeamWork

 

It's gonna take me some time to amass the materials and plan this all out. I have to learn a dance routine for my wedding .

 

I feel like ive seen something that i should never have seen and i cant un-see it.

That was like an anatomy lesson, ill never see my Zero 4 in the same way again.
Ive seen its insides *shudder*

oh btw - you are mental..!

 

Ha ha I'm so glad it's all still working. Gonna mess around with it a bit later on too; that headphone problem might just be fixable.

 

http://i29.photobucket.com/albums/c...Zero4 Disassembled/IMG00338-20100302-1843.jpg
Jesus Christ Super Star?

 

I worship at the Alter of The All Seeing TeLLy..!


Headphone output ? Tell me more.

 

Yep it came with the other 700 records I picked up a couple nights ago. I'm still going through them.
---

Not too much to tell so far. DJKeyWee is helping me out, as well as Sten from the DJF boards. More as it develops of course.

 

Yesterday I knew something wasn't that right in HeadBanger schematic b ut I suppose that it was due to my lack of sleeping (ok ok ok lame excuse )

This morning I'd checked the datasheet discover some mistakes indeed but tried it AS per the schematic providen on HeadBanger website. No fault it works, but not good as it should be.

So I'd re-design it a little bit and now here's a workable one that meet the part manifacturer needs, and us ears. Notice that it works better on power supply higher than 9 volts (higher gain, lower distortion). 12-15 recommended. There's also 2 component building a bass boost feature, those can be removed but give some interesting result on some headphone brands. The appended picture is for a single channel, just double it and away you go.

 

Wow that actually looks doable! Now I've got to figure outhow to power it...I want this all inside the mixer somehow. If I can't tap in anywhere on the mixer PSU, maybe access a battery compartment from underneath the line faders.

 

You'll be able to tap directly to the mixer PSU. Pin 8 of the NE5532 is V+, usually over 12V. I would bet you can also find some testpoint here and ther on the silkscreen of your multiple PCB. Maybe not a bad idea to measure directly from the PSU output then tap you wire directly there.

If you don't feel safe to do so, then... if you can place an extra connector on the backplate, use a wall wart transformer. If you do so, we may need to change 1-2 things to ensure proper PSU filtering. You don't want to use battery for that

FYI, I can make and assemble PCB here (even in SMD).

 

Yeah you lost me at "yesterday I..."

Something about Schematics ... Sounds like Jack Bauer needs something from Chloe..?

 

Seems like an Electrical and Computer Engineering Course
just in this thread alone. Wow, Love my zero4, do not have the guts
to rip its insides out. Its actually beautiful to see its organs spread out
like that. Its an electronic buffet

AMADO

 

Really you can? Awesome. How much would you want to build me up one? I'd rather someone with the skills did that part than have me fumble about. I'm sure I'd be able to find a 12V source from within the PSU....given some time of course. I really wish I had a "test" unit right now...

 

Since it seems that everyone in this thread has an IT and Engineering background,
then just to cordially introduce my self to this group then here is my background,
http://gsl.eng.fiu.edu/Amado/

Nice discussion

AMADO

 

Telly,
Let me check this for you, I feel I may need few of those, or variant of, for my own purpose anyway (not only DJ stuff but for other stuff).

When you can, try to measure all PSU rails and give me a list of the different voltages.

Tomorrow I'll also check my parts stock in case I have better solution handy. Amazing what I find each time I look in there. Buy a lot, receive a load of samples, classify them... but rarely try them

Amado,
welcome aboard