MAC - Micro Auto Compressor

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Blake
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Joined: Thu Mar 08, 2007 4:24 pm
Location: Perth, Australia

Re: Micro Auto Compressor

Post by Blake »

looks and sounds good Holger

a couple of questions if you dont mind,
which op-amps did you use in the MAC and the dINgO? im guessing OPA2604 or maybe the dINgO has something else?
and how are you mounting the dINgO?
Blake

deuce42
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Joined: Tue Sep 18, 2007 5:35 pm
Location: Sydney

Re: Micro Auto Compressor

Post by deuce42 »

Awesome Holger - thanks!

For the point of interest, could you tell us your signal chain so I have something to reference this to? Also interested in the op amps used for the Dingo like Blake suggests.

Thanks once again

deuce42

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Holger
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Re: Micro Auto Compressor

Post by Holger »

Ok, here's the finished one (in a nice surrounding)
Image
Detail shots
Image
Image
Image

I used the supplied 2604 in the MAC and simple 5532 in the Dingo. The finished unit (not the proto one where the soundfile is taken from) has two Altec 15356A transformers to match the sound with the look :)
Audio example: the signal chain is audio I/O via RME Fireface, left through MAC, right I/O directly patched.
My wiring is the typical DIY spaghetti stuff, but it's reliable and once the device is racked...
I still have a little mismatch ( ~1dB) between left and right channel when linked but I blame my hastily assembled Dingo's.
I did a mistake when doing the panel layout, so don't copy the ratio and meter writing, I had to mod the switches later to match the panel layout with the functionality :?
Last edited by Holger on Sat Jan 01, 2011 9:34 pm, edited 2 times in total.

audiohammer
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Re: Micro Auto Compressor

Post by audiohammer »

Joe,

Any progress on the mod to power a MAC and BAD both with 48VDC SMPS? What is the estimated time for a solution? :lol:

Or is the best approach to use the Power Rail Splitter with the MAC (with Dingo) and 48VDC connected direct to the BAD?

Also, are you selling the MAC VU meters?

Thanks!

chrisp
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Joined: Sun Mar 04, 2007 11:46 am
Location: Sydney, Australia

Re: Micro Auto Compressor

Post by chrisp »

Audiohammer wrote:Or is the best approach to use the Power Rail Splitter with the MAC (with Dingo) and 48VDC connected direct to the BAD?
The problem there is that "ground" for the MAC would NOT be the same as "ground" for the BAD. The BAD "ground" would be at the supply's 0V and the MAC "ground" would be 24V higher. Joe might correct me here, but an interstage transformer might be necessary between the BAD and MAC, and you'd need to avoid the MAC "ground" getting connected to the chassis.
Chris P
---------------------------------------------------------
I do lots of things. I believe eclectic skills are best.

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Joe Malone
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Re: Micro Auto Compressor

Post by Joe Malone »

The problem there is that "ground" for the MAC would NOT be the same as "ground" for the BAD. The BAD "ground" would be at the supply's 0V and the MAC "ground" would be 24V higher. Joe might correct me here, but an interstage transformer might be necessary between the BAD and MAC, and you'd need to avoid the MAC "ground" getting connected to the chassis.
Chris is correct but if the ground for the mac is only connected to the half rail on the BAD PCB and not 0v or chassis the 2 can work together. It is more to do with the MAC putting current to the MAC ground and pulling the half volts point on the BAD up and down that is the issue. There are a few simple ways around this but it will need some testing to work out which is best.

Below a couple of snaps of the MAC built versions. We have these running on our 48v SMPS external power supply with only 2 x 24v zeners to make that into +/-24v but a insulated DC connector is needed on the back of the case to keep the 48v floating.

Image

Image
Joe :-)
JLM Audio
Capturing Audio without Injury

conleycd
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Re: MAC - Micro Auto Compressor

Post by conleycd »

That enclosure looks great. Is it available yet?

CC

deuce42
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Location: Sydney

Re: MAC - Micro Auto Compressor

Post by deuce42 »

Given the excitement of a new kit coming out, I am surprised there aren't millions of postings about the MAC. I am eager to build this one but like the timid little baby that I am, I still hoping to let others be the guinea pigs first and then offer their advice and feedback before I plough into something I am not overly experienced with.

Is Holger the only one that has built one? Why everyone so quiet?? Is a MAC build thread like the Baby Animal build thread just a naive pipe dream of mine??.....

chrisp
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Location: Sydney, Australia

Re: MAC - Micro Auto Compressor

Post by chrisp »

Deuce

I've built both the MAC and the BA - don't wait, just jump in that deep end.

If you get the wobblies there's heaps of people here in Syd that have built the kits and would be willing to help. Plus JLM is famous for its support.

Just remember that the MAC kit is based on an optical compressor, which sounds and acts differently to a VCA compressor which sounds and acts differently to ....

Its a sound you gotta have in your arsenal, but its better for things like vox in my view than something like a drum kit. Although it can be interesting on a drum kit. Damn, why are there not hard rules in this game?
Chris P
---------------------------------------------------------
I do lots of things. I believe eclectic skills are best.

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Holger
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Re: MAC - Micro Auto Compressor

Post by Holger »

deuce42 wrote: Is Holger the only one that has built one? Why everyone so quiet??
Very good questions...
My MAC does what it is designed to do: it compresses audio signals. The compression happens in a gentle way, it does not do any harm to the time domain of an audio signal (my findings). Is it my first compressor choice? No. I often give it a try in the mix and finally take other compressors (I have a lot BTW). I would say that the MAC is a good recording compressor (in the 'set it once and forget it' kind of approach), I used it for guitar recordings and it works fine (if not very good).
Is it worth building one? Yes. It's cheap, easy to build and it's reliable, but I wouldn't say that it has a very special character.
Well, mine has a special look 8)
It's just a couple of dollars, you can' do anything wrong with building one. Technically it is well designed, two vactrols (detecting the entire wave, not only the positive half, as far as I understand). It has a good built-in meter option. The Dingo has the tranny option as well as the OpAmp option, maybe something I should consider as the next step to improve mine.
Again, why is everyone so quiet? Am I the only one who has ever built one? DIY world... hello...hello...hello

deuce42
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Joined: Tue Sep 18, 2007 5:35 pm
Location: Sydney

Re: MAC - Micro Auto Compressor

Post by deuce42 »

Chrisp and Holger - thanks to both of you for your encouragement and advice. You guys demonstrate that DIY is a kind and welcoming environment and I wonder how life would be if such socio-ethos were adopted in the outside world :)

Guess I will give the MAC a go. My real wish is to warm up the signal path going from the Mic/BA to my DAW. Something to add the sort of warmth that analogue gear has. My ears want to hear a close breathy vocal sound that I imagine would come from using- amongst other things- an LA2A (I am not naive enough to think on magic box is the answer). Perhaps putting 99V's in the Dingo may be a way of adding a bit of mojo if the MAC is otherwise uncoloured. I guess I was hoping the MAC would be like a poor mans (to be read, easier to construct) LA2A. Perhaps it will end up being something different again.

Currently I use a FMR Really Nice Comp in between my BA and DAW with the Supernice switch engaged. This does add some warmth, but since introducing the BA ended up being such a lifechanging step up from my Focusrite Trackmaster pre, I was hoping a new comp would be a similar step up from the super nice RNC when I'm tracking.

chrisp
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Re: MAC - Micro Auto Compressor

Post by chrisp »

The RNC is (I think) a VCA compressor that will sound different to the MAC: the MAC is warmer but slower in comparison, if that makes any sense. The MAC won't replace the RNC, but with it you'll have the choice of two different types of compression available.
Chris P
---------------------------------------------------------
I do lots of things. I believe eclectic skills are best.

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Joe Malone
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MAC + BAD wiring

Post by Joe Malone »

audiohammer wrote:Joe,
Any progress on the mod to power a MAC and BAD both with 48VDC SMPS? What is the estimated time for a solution? :lol:
Or is the best approach to use the Power Rail Splitter with the MAC (with Dingo) and 48VDC connected direct to the BAD?
Also, are you selling the MAC VU meters?
Thanks!
Build MAC PCB normally except
Change R14 on MAC from 2k7 to 4k7 - 10k
Leave off C7 and C9 for better noise floor

Other end of ribbon cable wire to

Pin1 – I pot terminal on BAD
Pin2 – 1/2v rail on BAD at opamp 1/2v pin (pin next to +V)
Pin3 - +48v on BAD at opamp +V pin
Pin4 - +48v on BAD at opamp +V pin
Pin5 – O pot terminal on BAD
Pin6 – LINK PIN for stereo linking
Pin7 - +OUT on BAD back terminals
Pin8 – 0v on BAD
Pin9 - 1/2v rail on BAD at opamp 1/2v pin (pin next to +V)
Pin10 – Not used

On BAD change R17 to 24v zener with strip closest to back of BAD PCB or a 4k7 resistor will work also.
Use two single 10k rev log if you want separate gain (0v & G1) and makeup (0v & G2) controls.
Otherwise dual control will do both at the same time and works fine. (No makeup pot should be wired to the MAC)
Joe :-)
JLM Audio
Capturing Audio without Injury

audiohammer
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Joined: Sat Oct 25, 2008 11:19 pm

Re: MAC - Micro Auto Compressor

Post by audiohammer »

Joe,

Thanks for the info! :D

audiohammer

tenchijin2
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Joined: Thu Mar 12, 2009 1:15 pm

Re: MAC - Micro Auto Compressor

Post by tenchijin2 »

Wasn't there some word about full stereo MAC kits coming soon?

Aric

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