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Ideas wanted -- USB DAC product
Ideas wanted -- USB DAC product
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Old 22nd December 2017, 09:01 AM   #71
blueskull is offline blueskull  China
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Join Date: Jun 2013
Location: RTP Metropolitan, NC, USA
Quote:
Originally Posted by MrMagic View Post
I've read they will open Thunderbolt 3 soon -in 2018 for more companies and with no royalties and it is the protocol of the future that will replace all other ports -but of course I understand it is your design / business choice taking into account several factors.
Intel said to open the standard in 2012 since the first debut of TBT1. It's always the next year.

Quote:
Originally Posted by MrMagic View Post
Finally! It took them 18 years to think of a reversible connector (1996-2014).
So in another 2 decades they will make it completely orientation free!
Talk about dinosaur progress.They should have asked a public school class to help them.
What do you mean by "orientation free"? Like a ball in a socket that can move and make contact at any degree? What's the point?

Quote:
Originally Posted by MrMagic View Post
Well, first, for a universal standard designed to be used by anyone from 16y olds to grandmas in everyday life that should have been able to plug it blindly, they have failed in an epic way.

Second, I'm not 16 and not clueless either, and I bet all members here, you included have attempted to plug a USB only to find out you need to turn it to the other side to your frustration. Now expand that number to the billions of USB consumers in the whole world x the number of failed attempts since 1996 and compare that to 10 minutes of thinking for a single developer required to figure out the proper connector design. That was my point.
I've plugged USB-A ports blindly to Ethernet jacks. And I believe I'm not the only one. But it doesn't hurt anything as Ethernet port is not supposed to be energized (no, POE won't deliver power besides a weak, current limited 5V initial voltage before negotiation).

Just flip it if you tried to plug it the wrong way around and it will be all fine.

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Originally Posted by MrMagic View Post
No need for overkill measures. You could use the master digital volume with two memory settings: one for the main DAC output and one for the headphone amp, then switch to the proper setting when the user enters the headphones mode, with the push of a button and/or by inserting a headphone plug, and provide an elegant touch volume control eg with light feedback and you're done, with the minimum hassle.
Will consider. I need some time working my spec sheet.

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Originally Posted by MrMagic View Post
Interesting. I will need an audio analyzer for my electrostatic headphones amp project -either I'll build one, or use one, but my measuring requirements are beyond 1ppm (<120db).
Will update. Stay tuned!

Quote:
Originally Posted by MrMagic View Post
You don't need to do that in an offensive way. My point was to design a scientific (read: repeatable) test that will prove the highest quality distinguishable from a significantly lower one, in an official, public test. If one achieved this, he would contributed to the audio community with that test mehod (would break a record actually). Everything else beyond an independently verified scientific test, is details. There should be ways to avoid offending and damaging the competitive companies.
Good point.
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Old 22nd December 2017, 10:57 AM   #72
MarcelvdG is offline MarcelvdG  Netherlands
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Quote:
Originally Posted by blueskull View Post
After seeing their picture I finally understood what did you mean by analog FIR. It's a low jitter 32-bit "SPU receiver" thing with analog coefficient programmed resistor per tap. I never thought of that -- that's indeed a good way of getting rid of the first stage of LPF opamp and to squeeze some extra THD reduction, besides to get rid of high bandwidth requirement of IVC opamp. As a side benefit, extra output levels grant higher DAC element SNR. That's a brilliant design with one stone hitting three birds.
I gather you are writing about a FIRDAC: digital delay line driving a bunch of DACs of which the outputs are added (with or without weighting). The main advantage of FIRDACs is reduced sensitivity to jitter. The patent on it has passed its due-by date, so you see FIRDACs all over the place nowadays.

Heinrich Pfeifer, Werner Reich and Ulrich Theus, Circuit arrangements for averaging signals during pulse-density D/A or A/D conversion, US patent 4947171, 7 August 1990
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Old 22nd December 2017, 03:07 PM   #73
MrMagic is offline MrMagic  Greece
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Quote:
Originally Posted by blueskull View Post
What do you mean by "orientation free"? Like a ball in a socket that can move and make contact at any degree? What's the point?
I meant cylindrical, with ring-like contacts, with a protocol that prevents short-circuit while inserting or pulling out by enabling the outputs only when the plug is fully inserted.

And you can make it completely zero-force, contact-free, (and water and dust/dirt proof) as it should be in our era, by replacing the ring contacts with coils that will transmit the data inductively, and provide a magnet at the tip that will hold the plug inside -which can hold or release the plug at will (even being pushed out) by a host tiny electromagnet.
We are already 6 decades ahead at the year 2077 -in dinosaur company years..

That is, if we'll wait for those dinosaurs, instead of making an open, free to license protocol with intelligently made connectors and make all other rubbish "inventions" worth only to through in a trash bin. Because the technology to do this, exists today and also existed many years back.

Last edited by MrMagic; 22nd December 2017 at 03:12 PM.
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Old 21st January 2018, 07:03 PM   #74
mkafridi is offline mkafridi  Pakistan
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The best way to lower the cost is to make the system modular...

This means that provide interfaces but attach cards!

Cards that provide additional functionalities like Ethernet, Bluetooth, headphone amplifier, DAC upgrade and others!

Think about this as a computer where I can add a graphics card, ram, Ethernet card, WIFI card, sound card!
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Old 22nd January 2018, 02:50 AM   #75
blueskull is offline blueskull  China
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Sorry for the loooong delay. I was working on the FIRDAC concept and I am still working on it. So far it seems very promising.

As for the connector based expansion card concept, I don't think this is going to work. USB interface is provided by DSP, and it is anyway needed for the normal operation of the system, as the DSP serves as interpolation engine. So the delta cost is zero.

Same for Ethernet -- anyway for device firmware update capability, I need an external CPU+ROM to load the DSP firmware and FPGA bitstream. A CPU+FLASH combination will be ~$2 minimum, and an ESP32 system on module (CPU+WiFi+Bluetooth+FLASH) is only $4.

And the same can be extended to WiFi and Ethernet -- they are provided on chip of ESP32, and the additional cost is only antenna cost.
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