Ok, since all the information seems to be spread around a few different threads, I'll add the specs of the converter to this thread, which is the technical information and development thread.
Stereo ADC PCM4222 A/D converter ADA4898 opamps High precision (0.5%) thin film resistors with lower noise than metal-film counterparts in audio path Film type filter capacitors for audio path Ultra low noise LDOs feeding analog audio components Input AC coupling only, DC coupling rest of path 44.1K-192K sample rates 16bit, 24bit depths S/PDIF output Clocking has 0.6ps phase jitter, 2ps period jitter, better than -130dbc/hz phase noise at 10khz offset 5hz->100khz +0.5dB/-3dB 15hz-30khz +/-0.5dB
Stereo DAC Dual PCM1794 D/A chips operating in dual mono mode ADA4898 opamps High precision (0.5%) thin film resistors with lower noise than metal-film counterparts in audio path Film type filter capacitors for audio path Ultra low noise LDOs feeding analog audio components DC coupling throughout audio path 44.1K-192K sample rates, automatically detected 16bit, 24bit depths, automatically detected S/PDIF input Individual power supplies for each D/A chip for maximum isolation 2hz->100khz filter bandwidth 5hz-30khz +/-0.5dB
Chassis: 30VA toroidal transformer 120/240VAC 50/60hz operation Intergral heatsink in chassis LCD for setting and status
I think I'll go simple and forgo the gui, and just have settings displayed and a couple buttons for each line that will just scroll through pre determined settings.
I think I'll go simple and forgo the gui, and just have settings displayed and a couple buttons for each line that will just scroll through pre determined settings.
The little LCD costs about 12$. 4 switches and caps cost around 2$ The PCB would be 5-10$ and there would a few $ of overhead for everything. I'd say around 30$ of parts to add a control panel to a device. COGS (cost of goods sold) would be a higher because it factors in design costs, assembly, storage, etc, so maybe more like 50$ when you factor in everything.
However, having a visual feedback system is absolutely priceless when it comes to features that sell things. It may only add 25% usefulness but it'll add 50+% in sales. The other good thing about it is that you won't have folks fishing around in the box flipping switches and such. That's seriously asking for a load of angry emails and calls from folks who've either shorted something out or can't figure out how to set things.
Anyway, I was going to have a complex GUI with menus and submenus and all the settings being adjustable, but the development time of such software is not trivial.
I'm no C coder, but I know enough to write a simple state machine to have a simple two line menu that you just scroll through the settings. You stop on the setting of choice and five seconds later it locks in and resets the chips with the new clock settings.
Anyway, the PCA in the picture above is one from a switch matrix I designed at my day job. I'll probably use something very similar, but probably cost reduced (single sided, lower quality FR material, etc.) It all depends on what I can cut the costs down to. I'll only go as low as reasonable to get the best cost/quality ratio.
I'll release more details as I get further into each piece. I've also contacted a few people who can make things happen for other pieces of the design.
I've cut where I could and added where needed. I'm pretty sure that it's going to be something unique, if not downright special.
On the technical side, I've been using an Arduino board to develop this. If anyone wants to learn how to code firmware in C, I can highly recommend using an Arduino first.
Got the simple menu working well. implemented an EEPROM read/compare/write routine in the button push functions so that each time a button is pushed, the stored value of the button push counter is compared to the eeprom value. If it's different then the eeprom is written with the counter value so that if the unit is powered down, the unit will boot up in the same state as it was when turned off.
So it'll have a single button that scrolls through the optional settings and wraps around. Dwelling on a setting for more than 3 seconds will lock in that setting.
Now I have to condense some of the conditional situations into much simpler and smaller functions and then map those out to pins on the micro.
Once I've done that, I'm going to finish the schematic with this micro and it's supporting components, then I can figure out what I want to do about laying it out.
I've done the schematic in orcad this time, but I don't have corresponding footprint libraries for the parts in the layout softwares that I have. I might still have to transpose this schematic to Circuitmaker which will require making a lot of part symbols and footprints, but at least I know how to do all that stuff. otherwise I'll have to bumble around in Allegro or PADS.
Post by tonycamphd on Oct 31, 2014 14:58:17 GMT -6
alls i can say is go svart! actually i'd also say/suggest, to keep it as simple and cheap as possible while still achieving the highest quality audio results possible, this is what ross did, and if it wasn't for the horrible delivery debacle, he'd probably have 3 times the orders in addition to what he can't keep up with currently..., and that would include me. Also, for me, looks are way way way on the back burner, i know some guys give a hoot about that, but it still doesn't stop them from buying the real deal stuff, and i'd guess that if the same item was available for $300 in ugly form, they'd spring for it way before they'd part with $500 for a prettier version of the same... at least for such an esoteric item. What i'm trying(badly) to say, is guys who are interested in this stuff, know what it is, no "sales pitch" needed...if ya know what i mean.
that's not right, let me fix that....
that's still not right, let me fix that again.....
I'm willing to pay $150 more to have it in a good looking case from dandeurloo. Even more if you stick a couple mf'ing battleship looking knobs and switches on that bad boy.
I just threw that out there because i know how fast things can get nickel and dimed up to the "it costs as much as everything else" bracket. Also, I guess if you put chickenhead knobs on it, i'd give you whatever $ you asked! 8)
that's not right, let me fix that....
that's still not right, let me fix that again.....
Anyway, cost is a big factor, but it'll still cost what it needs to cost to be as good as it can possibly be.
The clock oscillator alone costs 15$, but takes the place of two xtal oscillators, while giving 300fs of deterministic jitter.. that's the type of performance you see in 100k+$ test equipment.
I would have probably gone the route of communication via MIDI instead of an LCD display and buttons, but that's just me. With an open MIDI chart, so others could develop gui's for whatever OS or steering device... This would also be nice because you would be able to configure from whereever you are, i.e. maybe thru a simple vst's gui in you DAW or a standalone app. Just a fast brainstorm idea...
Last Edit: Oct 31, 2014 19:16:49 GMT -6 by Deleted
Getting pretty near done with the schematic. I've started figuring out the footprint names in the new layout tool and mapping them to the symbols. A couple more days til layout and then I do a parts check and hopefully have a few test boards made. I won't have all the parts to populate just yet since at least one of them has a two week lead time. I ordered it a week ago, but who really knows when it'll show up.
I'm willing to pay $150 more to have it in a good looking case from dandeurloo. Even more if you stick a couple mf'ing battleship looking knobs and switches on that bad boy.
