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MAX525 Aout SMD board


Altitude
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So I have been working the last month or so on a new surface mount based Max525 Auot module with integrated daughter board and level shifter.  The level shifter if based on the Midisizer Alf analog board and is adjustable from 5 to ~11V gates.  Sync24 is also included via normaled jacks so the signals are run to the DIN port on the 4xIIC module unless something is plugged into the 3.5mm on the break out board.

 

Critiques/comments welcomed and appreciated

 

aout_sch.pngaout_top.pngaout_bottom.pngaout_BO_sch.pngaout_BO.png

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Yeah,

 

I've been thinking about that, the headers will provide quite a bit of friction so I would only need one or two to keep it together.  The breakout board is designed to be panel mounted by the jacks so there is no need there.  I went with the cool LJE0352-4R / Kobiconn TRS 8mm jacks 

 

 

LJE0352.gif

Edited by Altitude
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Ah yeah good point on the jacks - I do the same thing. All panel mount connectors should be screwable to the panel - it makes things so much easier!

 

Good point though - if you're mounting it behind the jack board, you might be able to keep them together with glue or zip-ties. Looks like you have space to put a few screws in. For situations where it gets moved around a lot (like for live shows), the screws would be better peace of mind I suspect. Though, yeah since you can mount it behind the jacks, it's probably more optional.

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Probably a good idea to start going SMT for small-scale applications! Can I ask why you have decided on the 525 as a DAC? Better linearity than the TLV5630?  really progressed this year, I moved and now I'm occupied with Eurorack projects.

 

But, I still plan on using a SEQ V4 and/or a with analogue outs. Maybe I was too optimistic about getting the power from the modular though and I'm toying with the idea of a larger (3U x 126 HP) SEQ case with outputs mounted topside.

 

The idea of trimming the gate down from 12 V is a good one, it might also be a good idea to provide a regulated voltage for the offset control. as it makes bipolar trimming very difficult or impossible.

 

Perhaps a 1:1 header pinning from the core could be useful if there's space? And you might also want to keep the digital and analogue sections of the PCB separate, which is harder than it sounds!

Edited by latigid on
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I went with the 525 simply because I had the SMD parts on hand and it's supposedly a better part.

 

JP8 is the 1:1 pin connection from the core (or it should be anyway, I'll make sure to double check that).  I used the NorthernLightXs schematic from the Aout redesign page and that was one of his changes to the original design

 

The adjustable gate is very handy, I just built a TTSH and without that, I would have needed to build another device to deal with the high level gate requirements for that thing.  Figured it would be a more useful add on than the normal 5V level shifter 

 

What do you mean regulated voltage for offset correction?  Is there something more needed than the 6007 in the original design?

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Re: connectors, I guess it depends on which core you'll use! For the TTSH I have a gate booster pcb that also generates a trigger pulse kindly designed and routed/fabbed by people on MW. But I was originally thinking of similar oddball synths like the 2600 when I was playing with CV/gate breakout boards a year ago. It's still nice to have higher voltage available for non-Doepfer gear. My comment on voltage regulation was more applicable to systems with bussed power. If you have a regulated bipolar supply dedicated to this AOUT module, no problem. I hear that taking your VCO pitch reference directly from a power rail is not good design.

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  • 3 weeks later...
  • 2 months later...

Also very nice! Very clean designs. You seem to really know your stuff and you are working hard. I am waiting for a wilba pcb to be produced so that i can continue forward with my seq v4 and i keep running into your posts containing exactly what i'm looking for. It seems we are on the same path and you are about a year ahead of me any chance you will share your pcb designs?

 

Thank you.

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Altitude,

 

I have recently started to put together the pieces for a seqv4. I know i have missed the boat in a way. however i keep running into your posts and i have to say they are great! the pcbs you are designing are very useful and beautiful. It seems you are a few steps ahead of me in this process and i was wondering if you would share your pcb designs with me? this is my third midibox project. the first 2 were based on the pic18f core. I have been building a modular eurorack for almost a year now and i am very excited about sequencing it without a computer. I don't want to come off like a leech. I wish that i could contribute more but it seems like you know what you are doing. :smile:

 

Which core are you using? My stm32f pcbs just arrived from smash TV.  I bought have a couple of original aout pcbs from mikes midi shop which use the MAX25. i dont think that i need a level shifter for my eurorack but it would be nce to have 11 volt gates for other analog gear (hence your awesome all in one solution). Have you acquired a pcb for the control panel (wilba)? I am waiting patiently for them to appear on smash TV.

 

This should probably be a private message...oh well

Again, great work!

 

Cheers,

K-rAd

 

Edited by k-rAd MB6401
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I use the LPC cores right now, I have a layout for CNCing the holes for those and right now. I am doing a second rev of the Aout board, the first one had a bunch of mistake since the schematic I used which I assumed was correct had a bunch of errors on it. The prototype worked fine with all the fixes though. If you are not familiar with soldering fine pitch surface mount parts, I recommend you learn on something else. The Max525 parts are SSOP size which is VERY fine and at $25 each, its not a part you want to practice on. This board was made with the smallest possible footprint possible as the goal so the layout is pretty dense.

if you want to rack it, you might want to consider TK's new line length extender as well, the Aout is pretty sensitive to long data cables.

Once I confirm that the new rev is fine, i'll post the files

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