Hi everyone .
the choice for the I/V stage of the DAC is not easy (perhaps it is easier for those with OPAMP than discretes ) . how is it best to deal with it? which criteria to adopt? .
understanding what are the problems affecting the output signal and choosing an I/V that solves them, even if not completely, is this the best way? . admitted to being able to understand what the circuit can do, after having identified it (many times we start from the description by whoever designed the circuit).
I also assume that multibit DACs have different problems than DS ones
the choice for the I/V stage of the DAC is not easy (perhaps it is easier for those with OPAMP than discretes ) . how is it best to deal with it? which criteria to adopt? .
understanding what are the problems affecting the output signal and choosing an I/V that solves them, even if not completely, is this the best way? . admitted to being able to understand what the circuit can do, after having identified it (many times we start from the description by whoever designed the circuit).
I also assume that multibit DACs have different problems than DS ones
It depends of a lot of things, including the power consumption and heat.
In general - is better to use fast non-BJT OP, but is also depends of a schematic and DAC's output current (some OP can be used directly, some - with additionl transistors at the output).
I had a good results with OP42, OPA1656, LME49724/OPA1632, OPA1622.
In general - is better to use fast non-BJT OP, but is also depends of a schematic and DAC's output current (some OP can be used directly, some - with additionl transistors at the output).
I had a good results with OP42, OPA1656, LME49724/OPA1632, OPA1622.
An I/V converter is basically a transimpedance circuit. It converts input current change to output voltage change. The most simple form is a plain resistor.
One has to consider the output voltage compliance of the DAC, i.e. the maximum allowed voltage on the output at full scale digital input. This usually needs an I/V stage having very low input impedance (or a simple resistor with a couple Ohm value).
The other consideration is the transimpedance, i.e. the output voltage change divided by the input current change. In the case of a simple resistor as I/V, a voltage amplification stage should follow.
Some more considerations:
One has to consider the output voltage compliance of the DAC, i.e. the maximum allowed voltage on the output at full scale digital input. This usually needs an I/V stage having very low input impedance (or a simple resistor with a couple Ohm value).
The other consideration is the transimpedance, i.e. the output voltage change divided by the input current change. In the case of a simple resistor as I/V, a voltage amplification stage should follow.
Some more considerations:
- DC level shift, coupling capacitor
- Slew rate
- Noise
This seems like a rather lazy way to ask a question. Why don't you state the difficulties you have encountered?
until now I bought DAC already ready to use.
I'd like to try to assemble a modular DAC in order to choose power supply and I/V and LP stage if necessary.
I'd like to try to assemble a modular DAC in order to choose power supply and I/V and LP stage if necessary.
Modular is not the best way but for learning purpose. I mean the (choice) problems beginn since the output pin of the dac chip on its substract.
The layout and pcb design is one of the item on the list to deal with. It answers on electronic laws : frequencies, level ofcurrent, level of voltage, speed, distorsion, power noise rejection, transistors (bipolar, mosfet, etc), electro magnetism laws, tipology of the circuit choice which is dicated by the dac chip output characteristics and trade offs, passive parts, ,load of the next stage, skillls of the designer to balance measurements, trade offs, biass, listening check out and on what system (whch is not the last question), time, monney, selfbiass (should I tube, should I mosfet, should I bipolar, am I bipolar or just perfectionist, etc) !
So there are a lot of trade offs and the "game" is to reduce first the choice to avoid the worst choices if it is choosing a ready made of choose the best trade offs if it is your design. Certainly it asks to learn electronic little by little, modeling thanks to softwares and many free on line reading should involve your time until you old ages.
The first question maybe to wonder is to choose between the time you want to involve into electronic knowledge and the time you want to involve into listeniing to music as life is too short to correctly do both, and anyway do not involvve the same sides of your brain about pleasure and rewardness.
This time, if it's only about the music, the best is to save time and make a mortgage for a good gear between 1000 usd and sky limit, cause DIY is often between free (few bucks) and deep space limit !
I do not know if that helps ! Anyway there is a good book I do not remember the name about the learn of electronic and audio, several updated editions, didacted. IIRC it is named the Art of Electronic. Could be a good start to answer some of your questions and further if you want to invest more time or not.
my 1 cent + its diy part
The layout and pcb design is one of the item on the list to deal with. It answers on electronic laws : frequencies, level ofcurrent, level of voltage, speed, distorsion, power noise rejection, transistors (bipolar, mosfet, etc), electro magnetism laws, tipology of the circuit choice which is dicated by the dac chip output characteristics and trade offs, passive parts, ,load of the next stage, skillls of the designer to balance measurements, trade offs, biass, listening check out and on what system (whch is not the last question), time, monney, selfbiass (should I tube, should I mosfet, should I bipolar, am I bipolar or just perfectionist, etc) !
So there are a lot of trade offs and the "game" is to reduce first the choice to avoid the worst choices if it is choosing a ready made of choose the best trade offs if it is your design. Certainly it asks to learn electronic little by little, modeling thanks to softwares and many free on line reading should involve your time until you old ages.
The first question maybe to wonder is to choose between the time you want to involve into electronic knowledge and the time you want to involve into listeniing to music as life is too short to correctly do both, and anyway do not involvve the same sides of your brain about pleasure and rewardness.
This time, if it's only about the music, the best is to save time and make a mortgage for a good gear between 1000 usd and sky limit, cause DIY is often between free (few bucks) and deep space limit !
I do not know if that helps ! Anyway there is a good book I do not remember the name about the learn of electronic and audio, several updated editions, didacted. IIRC it is named the Art of Electronic. Could be a good start to answer some of your questions and further if you want to invest more time or not.
my 1 cent + its diy part
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"Modular is not the best way but for learning purpose".
this is a strong statement, explain to me why a modular DAC is only for educational purposes
this is a strong statement, explain to me why a modular DAC is only for educational purposes
Modular is not always a problem but here and for the DAC gears most of the time, it is better for electrical, so layout question, to use a standalone pcb. Mostly for the digital front-end, but also for the output of the dac chip in relation to the next current to volt conversion stage. If modular, i.e. longer distance, ground routing, impedances, etc, must be dealed with this purpose.That does not say it is impossible but must be seen as a trade off.
You can find a lot of threads in DIYAUDIO about that.
Of course alll the vendors of gears in kit with numerous options are knowing perfectly that and hope you see it as if you tune a car. They simply split the function to sold it in several boards to give you the feeling you are free of the choices and also because when the price is splitted you can grab more monney. That is not saying the design is optimal, that is saying what must be developped as a whole is splitted into concepts, local functions (as I/V for illustration) for marketing purppose if your goal is to purchase the function standallone wiyythout understand what happens around (and that dictates how must be this function you choose as a jean color).
It is by the way showed in Miro thread if you read it from the beginning. What some say they did but show they didn't. And eventually feel raped by a bull and invoque wrongly what being a gentleman is or not and in the same time did the opposit in a paranoid way! 😱 . Which of course is not involved in your question as you opened an open question in a standalone thread. Hence the motivated answer which is showing things are not as simple we'd like to.
You can find a lot of threads in DIYAUDIO about that.
Of course alll the vendors of gears in kit with numerous options are knowing perfectly that and hope you see it as if you tune a car. They simply split the function to sold it in several boards to give you the feeling you are free of the choices and also because when the price is splitted you can grab more monney. That is not saying the design is optimal, that is saying what must be developped as a whole is splitted into concepts, local functions (as I/V for illustration) for marketing purppose if your goal is to purchase the function standallone wiyythout understand what happens around (and that dictates how must be this function you choose as a jean color).
It is by the way showed in Miro thread if you read it from the beginning. What some say they did but show they didn't. And eventually feel raped by a bull and invoque wrongly what being a gentleman is or not and in the same time did the opposit in a paranoid way! 😱 . Which of course is not involved in your question as you opened an open question in a standalone thread. Hence the motivated answer which is showing things are not as simple we'd like to.
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"This time, if it's only about the music, the best is to save time and make a mortgage for a good gear between 1000 usd and sky limit, cause DIY is often between free (few bucks) and deep space limit !"
Man oh man, Ain't that the truth Iggy!!
But, the journey is much of the fun. 😉
Man oh man, Ain't that the truth Iggy!!
But, the journey is much of the fun. 😉
Yeahhhhhhh ! btw that's a long time I do not listening music anymore but just an old speech of Winston Churchilll on the radio in circle to test my diys (I surmise to be biased) ! If I knew that younger I would have learn to play a music instrument...
But I like the voice of this gentleman. And I know I will be finishing my old days at listening to Nietzche audio books, lol !
🙂
But I like the voice of this gentleman. And I know I will be finishing my old days at listening to Nietzche audio books, lol !
🙂