D-AOC PCBs - the building and help Thread

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Well-known member
Jun 4, 2004
Berlin, Germany
the history of this optical tube compressor:
23.04.2005 Optical tube compressor
02.05.2005 Optical tube compressor discussion
21.03.2006 Optical Comp
28.05.2007 The Optical Comp Again

for the PCB I would like to give some credits:
analag for the schemaic, gyraf for allowing me to use his G9 high voltage PSU, olafmatt for his heater PSU, kubi for improving everything.
kubi, bernbrue & jensenmann for beta testing.

resources for building the D-AOC PCB:
D-AOC Schematic
D-AOC component placement
a first rough, uncompleted BOM with sources from germany
Solens and Power Transformer Source in Germany (thanks to Jim50hertz)
WIMA MKP4s for the US (thanks to jrfred453)
Farnell Order Codes (thanks to MartyMart)
Parts for the US builders (thanks to MikoKensington)


the kubi advanced version

some cool observations by alexc

What are you using your D-AOC on? ;)

finished units:
bernbrue inside and outside
kubi & picture of the week
dagoose half finished and finished
Infernal_Death inside
Holgers Kubi advanced version
MartyMart inside and outside
Holger #3
Peter A
Hank Dussen
Hey Volker,

Good call on this :thumb:

Can you add the Edcor Transformer models you used here for others to see and if you used an off the shelf power transformer, which one?

From what I gather based on the schematics you need 3 secondary windings.

Sec 1 = 220 - 250VAC 0.1A
Sec 2 = 9VAC 2.5A
Sec 3 = 9 -24VAC



you will get all this information before the group buy closes, and some more.
I just don't have the time post all information in one day.

Audio Transformers (I will post measurements of different transformers when I'm finished with it).

Bernd and I have Edcor XMS10K/600 at the output with no problems.
they have a slight rise in the Highs when measured, shouldn't be bad or can be tamed with termination.

the Input will have to wait at the moment, but it looks like nearly any 1:1 transformer can be used. waiting for Edcor WMS 10K:10K at the moment to proceed.

for the prototype I used a custom wound 250V 0.1A; 9V 2.5A, 24V0.5A transformer (since I used 24V relays).
I wont mention the manufactur now, since I had a phone call from him today where he asked why he gets so many "custom wound" transformer orders from all over europe with the same specs I used and all mention some forums (and I think Klaus doesn't know what this is).
I can understand his point, he is not very happy to wind the same transformer every third day and ship it individually.
berndbrue / me are working on this right now, either we should do a group buy for this transformer, or finding a shop willing to stock them.

PLEASE: anybody knows my transformer winder, DO NOT order a single transformer for this project there now. we don't want to loose this source. we will find a solution.

Will try to find time to do the PSU and power transformer instruction tomorrow,
Hey Volker,

Totally understandable. I for one would LOVE to see a group buy on many of these things including the transformers. WIMA's are also hard to get here so maybe we can source some kind of Group buy on those as well.... hmm the possibilities are endless, LOL!

Thanks again for all the effort and to Analag for gifting us with a cool new 'none clone' project!


[quote author="matta"]WIMA's are also hard to get here so maybe we can source some kind of Group buy on those as well....[/quote]
the PCB is not limited to Wimas, even it was designed for Wima MKP4.
but kubi treated me a long time to put in more footprints ...
(drilling count increased a lot since he was involved)
Hi mates,
before I report about my first experience with this tube compressor I would like to point out a few things:

- this is a very "open", not profit oriented project, it would be a real pity, if this was ripped off or commercialized in any way
- it´s not a clone of an already existing compressor
- we would like to encourage you to DIY (including case and frontpanel design), since projects like this one becoming quite rare nowadays. So let creativity take its course
- Analag provided a very unique and fascinating schematic and got the ball rolling more than a year ago. Volker spend much time in designing the pcb and will have a lot of work and hassle to provide you with the pcb.
- Kubi supported Volker with suggestions and improvement

Volker was so kind to send me a prototype pcb of Analags Opto Compressor for beta testing. I suppose that this came to his mind: When a guy like me, a musician with such a limited knowledge in electronics can built this compressor, than everybody can do it. (foolproof so to say) :grin:

The pcb
well, it´s in blue, my favourite color. It was a real pleasure to stuff this board. The component placement is an amazing artwork, there are footprints for capacitors with different spacings and size, so it´s very difficult to find WIMAS that do not fit. You´ll enjoy it.

The building process
very straight forward, besides vactrols and Solen Fast Caps mostly easy to get standard parts. I haven´t paid all the bills yet, but my subjective impression is that overall costs a very low for a tube project

first impression: very subtile, unobtrusive compression, you won´t get it slamming

I talk to much, here are some pictures:




more to come later

[quote author="bernbrue"]
- we would like to encourage you to DIY (including case and frontpanel design), since projects like this one becoming quite rare nowadays. So let creativity take its course[/quote]

is this me being told off? :grin:

I understand what you mean about creativity, but in the UK this cost lots. I can get a full case plus front panel from Tat for cheaper than i can get a local guy to make a front panel.

thats one pretty build you have there sir!! and am very pleased to hear that this will be subtle rather than smashing compression.

Thanks to everybody who has worked on this!!!!!

im thinking about sending edcor in the states an email about the custom power xfmr, they sent me a sweet one for my federal vari mu project, should i hold off? do you have something clever on the way?
Sorry if this is a bit premature but just scouting around to see whats available,

Does any one have a UK / EU source for the regulators?

LM350T & TL783?

or are their equivalents we can use?

also would MKS4 Polyethylene-terephthalate Wima Caps be ok, instead of the MKP4 Polypropylene ?

looking forward to this one!

really! i searched and it said 'special order', meaning they come from the states...ill check again..

not much sleep lately...sorry..
LM350T – P/N 267-9917 (RS)
TL783 – P/N 9594582 (farnell)

RS only sells the TL783 in tubes of 50.


I just wanted to mention that I sucessfully tested a simple 250uA Amperemeter with the D-AOC. Basicly it works, though the tracking in comparision to a sifam AL29 is not very convincing. Volker tested a 1mA meter, but the needle barely moves. Anyway, I recommend to test various meters, before buying quite expensive VU meters.

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