Thanks ! I am using Dim's project https://www.dimdim.gr/2015/06/universal-usb-to-i2s-interface-indicator-pcb/ . It is described in detail!
Some R2R DACs have an output pin which sources or sinks a constant current from the DAC's Iout pin. PCM58 is one such, PCM63 is another. Connecting this pin to the Iout pin turns a unipolar output current into a bipolar one. BPO stands for 'bipolar offset'. The current source connected to the BPO pin normally has a filter cap associated with it to lower its noise.
More recent designs of DACs (PCM1702 and PCM1704) have the filter cap, connected to 'BPO DC' but no BPO pin is brought out, its internally hard-wired to the Iout pin.
As a continuation of the Idea to keep the DAC simple. Here is an idea for a discrete I/V converter running on the same rails as the DAC.
JFET based IV converter with no GNFB, minimal part count, Low pass and highpass are built in.
Very Low THD and Noisefloor in Simulation.
We should essentialy look at designs with no output caps, imho... that's a big plus when they are out of the output !
Clever designs when discrete should focus if we talk about simplicity to avoid transistors sorting out with of course the trade off than best THD à la ZEN are certainly above because of that. The liberty though gives the margin to not design like Sparkos with smds only...
Clever designs when discrete should focus if we talk about simplicity to avoid transistors sorting out with of course the trade off than best THD à la ZEN are certainly above because of that. The liberty though gives the margin to not design like Sparkos with smds only...
For I/V i don't see any issues, you won't be making a space heater with any design. High powered amps yeah, this, not so much (even zen uses smd transistors). Sound wise, i have honestly failed to hear the difference. It all comes down to designed schematic and best practices, in which smd can outshine th easy (think resistors with no legs and it's benefits, np0 capacitors, etc).
But yeah, i get your point of view, if it runs too hot, use bigger package
But yeah, i get your point of view, if it runs too hot, use bigger package
well I am not too much found of X7R and NP0 either in analog design but since we has some good other smd caps type from some years, analog designs with smd caps are sounding way better than before when it comes to full smd designs for analog circuits (if avoiding ceramic ime). Resistors, yes, they are ok and choice is there!
But the point is not smd is always a problem in what I said, but just it can gives limitation if designing not only for the sound but other trade offs like to want to make the size to swap a dip-8 because it is easier to sell. Here we do not care of such things, limitations are often elswhere as sorting out thousands of discrete whatever the reason : time, monney, ... and for smd we do not ssuffer always of space lack !
But the point is not smd is always a problem in what I said, but just it can gives limitation if designing not only for the sound but other trade offs like to want to make the size to swap a dip-8 because it is easier to sell. Here we do not care of such things, limitations are often elswhere as sorting out thousands of discrete whatever the reason : time, monney, ... and for smd we do not ssuffer always of space lack !
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I love new smd tantalums They work beautifully. Still have bad karma due to issues way back..
There are more advantages to smd, and why we should all try to move to designing with it. Availability. For example, marks smps filter is excellent, but trough hole components it uses are getting more and more scarse, to the point where th current sense resistors are eol, and are replaced with smd ones. I designed a pcb with smd parts, and added benefit is size.
Yep, tbh all chips here would be better off with smd caps, not just tda
They work beautifully. Still have bad karma due to issues way back..There are more advantages to smd, and why we should all try to move to designing with it. Availability. For example, marks smps filter is excellent, but trough hole components it uses are getting more and more scarse, to the point where th current sense resistors are eol, and are replaced with smd ones. I designed a pcb with smd parts, and added benefit is size.
Yep, tbh all chips here would be better off with smd caps, not just tda
Removing the Capacitors from output path is possible
1. by adding another servo. Can use a single TL072 per channel.
2. You can notice there is no need for Capacitor at all as the DC at output can be set to zero with a Variable resistor. the Cap is optional.
3. I still like the idea for a capacitor coupled output as this will smooth out the DC from the original R2R signal, (I believe that R2R needs to have a high pass and low pass)
2sk209 is the SMD derivative of 2sk170, so you can still do a fully through hole version of the same. But I wanted to design with parts that are readily and cheaply available. Possibility to use other n-channel jfets including Linear Audio ones with minimal changes.
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Did you simulate the PSRR of this circuit, especially to the positive rail ?
Patrick
If I compare the datasheet, I think it is more like the SMD version of 2SK117, with much reduced dissipation.
Patrick
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Hello
I have a complete Ian Canada FiFOPi, dual DAC line, but I'm curious to R2R and have already purchased everything for the 1862 DAC.
I have two questions:
1. has anyone compared the FiFOPi + dual ESS DAC with the FiFOPi + miro1862 version?
2. In principle and in practice, can I use both DACs at the same time if I connect them to the FiFOPi (direct and I2S connection)?
Thank you
Gyuri
I have a complete Ian Canada FiFOPi, dual DAC line, but I'm curious to R2R and have already purchased everything for the 1862 DAC.
I have two questions:
1. has anyone compared the FiFOPi + dual ESS DAC with the FiFOPi + miro1862 version?
2. In principle and in practice, can I use both DACs at the same time if I connect them to the FiFOPi (direct and I2S connection)?
Thank you
Gyuri
Gyuri, this can hardly be answered, if at all. All the different possible PSUs, clocks, cablings, etc. One can take the effort to the extreme and if you like,......
What I can say:
I had (and have, but don't use) an IAN 9038 system with some very well working independent power supplies (yet neither supercaps, nor accus), but with Andrea Mori clocks.
And I have a set of Miros DAC with PSU2, JLSound USB and different IV setups.
My verdict: IAN Fifo DAC sounds almost perfect I would say and with Miros DAC I like to listen very much.
Semiofftopic:
But in fact I mostly listen with an RME ADI2Pro because of its 2 independent stereo outputs (each pair has its own DAC) and the individual PEQ setting options for each of the 4 channels. In my opinion the RME surpasses IANs setup - in sound it is at least not worse and regarding the ease of use the RME wins hands down. AND, ADI2Pro can output 2 of the 4 channels (one stereo pair) PEQed via Spdif to the Miro DAC (connected to main speakers). So I can include Miros DAC with all the comfort of the RME device in my system. The other two channels - coming from the internal RME DAC carry the signal to the subwoofer (which really needs EQ in my room).
Semiofftopic off.
Why I mention this - for my ears the AD1862 is so pleasant to listen to that I accept this effort.
R2R NOS of not NOS, that is the question? For some it is what they are looking for, for others this is a nogo. Checkitout.
2nd question: i2s is a one way data transmission. So I guess, you can. Yet both DAC will show different timings. IANs Fifo Ding will be late by a margin.
Cheers
What I can say:
I had (and have, but don't use) an IAN 9038 system with some very well working independent power supplies (yet neither supercaps, nor accus), but with Andrea Mori clocks.
And I have a set of Miros DAC with PSU2, JLSound USB and different IV setups.
My verdict: IAN Fifo DAC sounds almost perfect I would say and with Miros DAC I like to listen very much.
Semiofftopic:
But in fact I mostly listen with an RME ADI2Pro because of its 2 independent stereo outputs (each pair has its own DAC) and the individual PEQ setting options for each of the 4 channels. In my opinion the RME surpasses IANs setup - in sound it is at least not worse and regarding the ease of use the RME wins hands down. AND, ADI2Pro can output 2 of the 4 channels (one stereo pair) PEQed via Spdif to the Miro DAC (connected to main speakers). So I can include Miros DAC with all the comfort of the RME device in my system. The other two channels - coming from the internal RME DAC carry the signal to the subwoofer (which really needs EQ in my room).
Semiofftopic off.
Why I mention this - for my ears the AD1862 is so pleasant to listen to that I accept this effort.
R2R NOS of not NOS, that is the question? For some it is what they are looking for, for others this is a nogo. Checkitout.
2nd question: i2s is a one way data transmission. So I guess, you can. Yet both DAC will show different timings. IANs Fifo Ding will be late by a margin.
Cheers
Hello Patrick
The PSRR is very low. But the initial idea was to power it off the same low noise high psrr Rails as the DAC. +/-12v.
Later on I realized it only looks good on simple simulation. But when simulated with DAC output impedance of 1500ohm (worst case of AD182, based on spec sheet), it did not hold the scrutiny, Needs multiple parallel 2sk209BL in parallel and a higher positive Rail voltage to reduce the input impedance to meaningfully low level that it is not affected by DAC output impedance.
After multiple direction Changes, This is what I ended up with (18 ohm input impedance). Planning to prototype this.
Thanks
Mallik .
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Hello patrick,
Here are the PSRR results, it is non existent . Exactly the reason why it has to be run on the same high PSRR rails as the DAC. (walt jung PSU or a CRC followed by 7812/7912)
Here is the THD sim with single pair of JFETs.
Wanted a THD of -80db or lower, so aborted the single pair version.
Thanks
Mallik
Here are the PSRR results, it is non existent . Exactly the reason why it has to be run on the same high PSRR rails as the DAC. (walt jung PSU or a CRC followed by 7812/7912)
Here is the THD sim with single pair of JFETs.
Wanted a THD of -80db or lower, so aborted the single pair version.
Thanks
Mallik