Mixer mods

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Warwick720

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Hello! I recently picked up a Mackie Micro 1202 for recording to ADAT. Decent little mixer for super cheap, but since I've had good results modding instruments, it seems like it'd be pretty easy and cheap to improve it.

First, I'd like to give at least four channels pre-eq and fade direct outs (Ideally 8, but for now I can use the inserts for the first 4).

Second, since there's only a 2-band EQ on each channel, I'd like to tweak cap/resistor values to tailor the EQ to the two most important frequencies I'll commonly use on a particular instrument. For example, any given channel could be permanently assigned kick drum duties, so for the LOW band I might leave the stock 80Hz or bring it up a touch, and change the HIGH band (stock 12k) to something around 400Hz. There'll be another channel designated for bass guitar, etc. As an added bonus, I can use better quality components!

The questions I could use a little help with are: How should I determine the component values involved? Is there a formula/software of some kind for this?

And are there any other modifications you could recommend?

Thank you!
Preston
 
Before you start "tweaking" a device like a mixer you need to "specc' it out"!

This involves checking the gain, noise and frequency response* of each channel and monitoring path. To do this you will need a calibrated (for F and V) audio signal generator and an accurate audio millivoltmeter. The meter should have a full scale sensitivity of at least 1mV and better 1/2 that.

If you have a good sound card in your PC you could use some free software such as RightMark but you will still need to build some outboard interfacing attenuators and very low noise amps.

Having GOT a specc' you can now proceed to fork it up.

Next you will need a schematic of the mixer and that could take you 5 mins on Google or never!

Do not think about "better" components. Unless some device has suffered obvious heat stress all will be the best they need to be.

Lastly. It seems you want to EQ "going in"? The usual practice is to record flat and dry then use the EXCELLENT and VERSATILE EQs you will find in almost all DAW softwares.

*You should also really check the distortion and crosstalk but let us K.I.S.Sir for now?

Dave.
 
ecc83 said:
Lastly. It seems you want to EQ "going in"? The usual practice is to record flat and dry then use the EXCELLENT and VERSATILE EQs you will find in almost all DAW softwares.
Click to expand...

He says he's recording to ADAT.
 
ecc83 said:
OooooKaaay. But it won't STAY in ADAT will it? Be mixed out to sommat.

Dave.
Click to expand...

Oh ... I guess I just assumed he was going old school all the way and mixing it old school too with all outboard. I'm an analog fan, so I try to avoid working with a mouse as much as I can. :)
 
Schematic is absolutely necessary. If you can't find one, you'll have to trace it out yourself.

The direct outs should be easy if you really want them pre-EQ. Your easiest answer will be to connect the direct out in parallel with the insert point. Decide if you want it pre- or post- insert and just tack it onto the appropriate lug.

As to the EQ f = 1/2piRC. The R's usually want to be set based on the impedances around the filter, and since they're already there, I think you'd just have to calculate the Cs. In fact, since you know f, and can find C by reading the cap, it should just be a matter of a simple inverse proportion, right? f2/f1 = C1/C2, C2 = C1f1/f2. "Should" work no matter the topology of the filter.

Schematic is still necessary.
 
Thank you everyone for all of the helpful information!
I do record dry, into the adat, and mix analog. You're correct in assuming my goal is that the recordings stay as far away from the computer as is feasible.

The schematic I can get from Mackie, they just require the serial number of the mixer, so I can get that next time I'm at the studio.
 
Just one thought about messing with the eq. In your example, you wanted to take the 12k eq and move it down to 400hz. The trouble with that is that it is a shelving eq. If you simply change the corner frequency, you will be turning everything above 400hz up and down, instead of just the area around 400hz. Turning a shlving eq into a peaking one might be more difficult.

If you were to change the high shelf, my vote would be something more around 8k. That seems to be my go-to for sparkle and air...
 
Warwick720 said:
Hello! I recently picked up a Mackie Micro 1202 for recording to ADAT. Decent little mixer for super cheap, but since I've had good results modding instruments, it seems like it'd be pretty easy and cheap to improve it.

First, I'd like to give at least four channels pre-eq and fade direct outs (Ideally 8, but for now I can use the inserts for the first 4).

Second, since there's only a 2-band EQ on each channel, I'd like to tweak cap/resistor values to tailor the EQ to the two most important frequencies I'll commonly use on a particular instrument. For example, any given channel could be permanently assigned kick drum duties, so for the LOW band I might leave the stock 80Hz or bring it up a touch, and change the HIGH band (stock 12k) to something around 400Hz. There'll be another channel designated for bass guitar, etc. As an added bonus, I can use better quality components!

The questions I could use a little help with are: How should I determine the component values involved? Is there a formula/software of some kind for this?

And are there any other modifications you could recommend?

Thank you!
Preston
Click to expand...

you can only diamond stud it to a point.
but I would recommend if you want nicer eq channels:
get a patchbay, breakout your inserts then get something like this: Harrison Consoles: 832c Filter Unit. that away you can start moving into the outboard equipment in the correct direction.
 
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