What is blameless, really?

[spaceistheplace]

@JPS64: what I had in mind was pretty much the 19" case from modushop, with custom front and back panels.

What you describe looks a lot like the lunchbox enclosures common in the pro world.

The card slot idea is nice.
I first had in mind something like the Cello Audio Suite:







I’ve seen a more contained use of this method from quad, accuphase and other manufacturers for optional MM / MC phono add ons.

 

[leadbelly]

I like the cardslot, but it can be argued that it is a more powerful standard without a cardslot.

The higher priorities should be in what are the obstacles to the example being argued over. Say you build a big all encompassing preamp. The new gotta-have-it DAC comes out the year after. What's going to stop you from doing surgery? 1) does it even fit? 2) new mounting holes? 3) PS will have to be changed? 4) interface circuitry (buffer, divider, gain)?

 

[spaceistheplace]

@spaceistheplace
Good luck with this egg-laying wool-milk-sow project.

JP

I’d never heard of “eierlegende Wollmilchsa” Thanks for that. I got a good laugh. But really I’m just trying to perhaps encourage more mindful, cooperative efforts. More like what lead belly mentioned: http://www.ntrak.org/documents/Manual.pdf Then others can decide if it lays eggs, provides milk, breathes fire, etc.

I like the cardslot, but it can be argued that it is a more powerful standard without a cardslot.

The higher priorities should be in what are the obstacles to the example being argued over. Say you build a big all encompassing preamp. The new gotta-have-it DAC comes out the year after. What's going to stop you from doing surgery? 1) does it even fit? 2) new mounting holes? 3) PS will have to be changed? 4) interface circuitry (buffer, divider, gain)?

How would you do it, from top to bottom? Give me your vision.

Edit:
Future proofing and ease of adaptation are of course primary goals. I’m of the mind that there’s no need for Swiss cheese chassis drilling. I’d imagine the place to begin is evaluating the viabilities of different form factor, backplanes, cardslots etc and then over to PSU and standardization with the modules and then the controller.

But maybe it’s wise the other way around. Also another standard that I found interesting is grid beam: How to Build With Grid Beam | Cool Tools

I'm not sure there's a way to herd all the cats active on this forum.

I don’t believe so either. I set my sights pretty modestly hoping to herd just a handful of cool cats, ideally house trained. ;-) No need to herd the hissing, spraying types.

Yourself, VenusFly and Leadbelly seem to also intuitively understand the benefits of what I’m advocating. I believe more will follow once they realize the utility.

PS for a pro audio / synth community example, take a look at the items built around the 500 series modules: Www.manamodular.com
Fredenstein Bento 6S 6-slot 500 Series Chassis | Sweetwater
List of all 500 Series modules on ModularGrid

Notice some of the larger modules simply take up 2 card slots. Look at the 508 DIY backplane: Classic Audio Products, Inc.

And someone’s build log of the above:
Starting a modular console - CAPI/GDIY 508 rack build








Why this isn’t a totally sensible concept for some for diyaudio is a head scratcher.

I guess it takes us a while to catch up to the more practical, level-headed pro audio folks.

 

[JPS64]

The 19 inches standard defines cards inserted in the front and from the rear.

I´ll give details of my thinking:

- MM/MC slot: different rear input cards for MM and MC; since years the levels are well known; MM/MC preamplifier electronic on the 160x100mm front inserted board; needs power (in voltage and wattage) and gives defined (hardware ICD) output signal level (no problem with differential or single ones, has to be clearly defined in the hardware ICD); add I2C (software ICD) for micro whos control switching (R/C) and other stuff; another board (upgrade) needs to be compliant with hardware and software ICD; define the type of backpanel connector (2mm metric, DIN41612) and allocate the signalling
- DAC/ADC/BT aptX HD slot: different rear entry board with connectors for USB, HDMI, I2S (would use standard RJ45); I´m developping one stamp board for ADC (I2S) and one stamp board for DAC (I2S), the CSR8675 (I2S) stamp board would be a chinese COTS, UAC2 transceiver in the pipeline but something from TI or XMOS will do DoP; on the frontmainboard; micro for configuration and communication over I2C; define the signalling on the backpanel connector (same I2C, power, I2S for DSP?, line level); new developmet welcome according hardware and software ICD.
And so on...
First, write the detailled technical specification which defines clearly the requirements to become a standard; then extract the ICD; peer review before publishing. Electronic card developper supplies board according technical specification requirements and ICD.

I´ve build a lot of 19 inches equipment for avionic systems; they all praised the modularity of the equipment (electronic card interchangeability according existing ICD). We´re talking about well known FFF Fit Form Function.

JP

 

[JPS64]

Schroff Download Center | nVent
Document: https://schroff.nvent.com/wcsstore/...off_cat_39601299_standards_summary_2005_e.pdfSchroff Design Guide-2 Standards summary for electronics packaging

JP

 

[00940]

Time to learn kicad... Plenty of diyers stuck with the 80*100mm free area in eagle.

BTW, PCB costs greatly increase above the 100*100mm size.

 

[leadbelly]

I think the cardslot idea is nice, but going down too far down the road of standardizing sub-assembly signals will just make it onerous and it will just never take off.

There is actually one example I can think of for DIY cardslots, and that is the Seymour Duncan Convertible guitar amp, where you did have a small number of fanatics building DIY PCB cardslots to insert into the amp.

I think just defining a physical attachment standards, such as 4 holes for standoffs say 3" apart forming a square; an analog input standard, such as 1Vpp at 47K; an output standard; a PS standard such as +/- 18VDC at 1A, and some standard around unbalanced/balanced would be all you need. No need to worry about I2C, I2S, USB, those take care of themselves. This is just an example of course; effort would be needed to come up with an effective standard. I think the power would be in making something simple, so if a designer wasn't interested in the standard, but did make his PCB work available, someone could make it comply fairly easily. Also note that in my example, no problem making perfboard or vero board work as well.

 

[00940]

I dunno. I've given it some more thought.

Let's take a modushop slimline 3U, 170mm deep, 415mm wide (inside) at less than 50€. We can easily fit 10 cards, 100*100mm, in 40mm slots. There is ample space behind the backplane to fit connectors. Even assuming the power supply takes 2 slots (it would make a lot of sense to have an external laptop supply and an internal dc-dc switcher), that's 8 slots free to use.

A 415*120mm backplane in 2mm thick fr4 (for some extra rigidity) would only cost about 20€ after taxes.

PSU wise, I'd want at least +/-15V @1A, 5V @1A (isolated), a digital control line. What could be a nice challenge is how to arrange the analog busses on the backplane for a maximum flexibility.

 

[spaceistheplace]

09 Your thinking is tracking with mine pretty closely.

I guess I/0 could be handled on the backplane with relays and jumpers.

8 slots gives you:

Controller
PSU 1
PSU 2
DAC
PHONO
Buffer / Gain
Attenuator
Wildcard

Since there’s so much flexibility I don’t see why a separate power supply would be a deal breaker. Also, it would be audiophiliac approved.
PSUs separately or shielded some way in the chassis would also be nice. Or you could go a size up on chassis and have an unslotted area for psus in the back with controller up front. (Not backplane pluggable) Or; perhaps have provisions for daisy chaining chassis, for the multichannel folk and so on.

 

[spaceistheplace]

Also I’d rather have expansion built in out of the gate or at least maybe sizing up on the 8 slot concept. It doesn’t leave much room for experimentation or comparison and I don’t think a certain potential or common use case should be a limiting factor. Then we are playing the game we want to get out of. Leadbelly and others have raised some issues regarding multichannel and other use cases. And I left DSP out of my previous list. That would fill up 8 slots pretty quick. Nonetheless I agree with your basic premise and it doesn’t seem as complicated or onerous as some have made it seem. Especially so when others become intrigued and engaged by the idea as having potential to meet their needs.

 

[00940]

That was 10 slots among which 2 for PSU. If you take a deeper case, the PSU can be behind the backplane, which gives you 10 full slots. A screen probably needs two slots width.

 

[JPS64]

A screen is mounted on the front plate so no extra slots (take one intelligent with serial); cards are slotted from the rear so no holes in the front. But you´re putting the cart for the ox. Write your preliminary ideas down on paper.

@00940
20EUR (or dollar) is very optimistic; 50EUR for HIFI2000 enclosure, but without drilling (and you need rail system)!

 

[00940]

Actually 156€ before taxes for ten 2 layers, 2mm thick, 415*120mm PCB from smartprototying. So 20€ with taxes but without shipping isn't too far off.
In a lunchbox system, cards are inserted from the front and held by the frontplate and the connector on the backplane. So no need for rails. What wasn't factored in is the cost of the custom front panel.

 

[billshurv]

I've been tempted by the modular arrangement a number of times over the last 30 years but each time stopped when I realised that, for most use cases it increases cost several fold for no real benefit. Also you rapidly end up having to design it like a mixing console.

Current missing creep revolves around using insert switching ( hifi calls em tape loops) but now I can't help thinking that DSP is the answer. Digitise all analog as early as possible, process in DSP and i2s to whatever DAC(s) gets you moist.

 

[gpauk]

Absolutely. Get anything that isn't already in the digital domain there as early as possible!

 

[billshurv]

And then the challenge becomes EQ with a decent user interface. (and I have odd requirements on that as well).

 

[00940]

I wish someone made an interface for hifi as intuitive as this one: Soundcraft Ui

 

[JPS64]

That´s a good raw price! IMHO, it´s really too early to talk about price without definition. Right, you don´t need rails with lunchbox system. I´m out, I don´t like the style and more important the lunchbox backpanel connectors (but I´ll continue to follow this thread).

good luck in your tentative.

JP

 

[spaceistheplace]

I've been tempted by the modular arrangement a number of times over the last 30 years but each time stopped when I realised that, for most use cases it increases cost several fold for no real benefit. Also you rapidly end up having to design it like a mixing console.

With the controller in front with display and knobs, I figured they’d slide into the back... making appearances much nicer. The only practical way I think to control and calibrate everything would be arduino or better with a large OLED or LCD screen. More adoption can drive costs down considerably. Think about a group buy.... Also, perhaps working with hifi2000 or even diyaudio store can make a difference.

Current missing creep revolves around using insert switching ( hifi calls em tape loops) but now I can't help thinking that DSP is the answer. Digitise all analog as early as possible, process in DSP and i2s to whatever DAC(s) gets you moist.

DSP would be integral but you have to consider the most versatile end product for everyone. I’m not sure how it will play out. But ensuring the most versatile foundation would drive adoption and thus reduce cost to those involved.

 

[spaceistheplace]

That´s a good raw price! IMHO, it´s really too early to talk about price without definition. Right, you don´t need rails with lunchbox system. I´m out, I don´t like the style and more important the lunchbox backpanel connectors (but I´ll continue to follow this thread).

good luck in your tentative.

JP

I agree the mixing front style isn’t ideal. I posted the Cello stuff as a conceptual suggestion. The type of connectors or backplane design is wide open. Can you explain what you don’t enjoy about them? Personally I think loading them in via a back panel and keeping the front decidedly hi-fi with a nice display and knobs will be the only solution that will see enough adoption to keep the project alive.

As you said nothing is decided upon it’s just chatting, but I would hate to lose what’s been fantastic insight from you and what seems to be a solid knowledge of some of the pitfalls we may face. What would you change? How would you do it? I’m eager to listen to your wisdom on the matter.