I would think it possible. One way to find out is try them and then jumper them out with a piece of wire. If the sound changes for the better or for the worse with a jumper you will likely notice. If no change, then do you really need the chokes? Also, I use common mode chokes on the AC line in my power conditioners. The ferrite material there is very soft. Seems to do more good than harm in that location and with those particular chokes, so I use them. In other cases I remove ferrites when they seem to be doing more harm than good.
https://www.analog.com/en/resources/analog-dialogue/studentzone/studentzone-june-2017.html
I have found data that may be useful for the input bias current compensation resistor at the output stage.
According to this document
1. The conceptual resistance value is Rs||Rf.
2. Compensation resistance may be unnecessary depending on the type of off-amp
Noise can be added.
3. Protect the part if the sequence timing of the split power supply circuit is different.
4. If you are adding a compensation resistor, it is recommended that you install the bypass cap.
I have found data that may be useful for the input bias current compensation resistor at the output stage.
According to this document
1. The conceptual resistance value is Rs||Rf.
2. Compensation resistance may be unnecessary depending on the type of off-amp
Noise can be added.
3. Protect the part if the sequence timing of the split power supply circuit is different.
4. If you are adding a compensation resistor, it is recommended that you install the bypass cap.
@altor
It does not exceed the short-circuit current specified in the datasheet of the opa1612.
In other words, the previous schematic would require a series resistor of 200 ohms to sufficiently reduce the short-circuit current,
but this would suffice with less than 100 ohms.
And it reduces the cost of some high-end resistors and film capacitors.
It does not exceed the short-circuit current specified in the datasheet of the opa1612.
In other words, the previous schematic would require a series resistor of 200 ohms to sufficiently reduce the short-circuit current,
but this would suffice with less than 100 ohms.
And it reduces the cost of some high-end resistors and film capacitors.
Nothing will happen with a total of 100 Ohm as common. Calculating worst case is good but assuming full rail voltage to the muting-to-GND contacts is a bit too much I think. The IC will not be damaged as it limits current anyway and offset voltage settles very fast to near 0.
You can also use just one relay for both unbalanced outputs for simplicity/reliability. In case of balanced (I think the way of drawing is hard to read) outputs you could add solder blob jumpers to configure muting as shorting - and + outputs to each other instead of muting to GND. That is what I do with universal muting boards and it works OK.
You can also use just one relay for both unbalanced outputs for simplicity/reliability. In case of balanced (I think the way of drawing is hard to read) outputs you could add solder blob jumpers to configure muting as shorting - and + outputs to each other instead of muting to GND. That is what I do with universal muting boards and it works OK.
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Compared to what?
In my version - I not use opa1612, and my output RCR circuit have 24R instead of 100R resistors.
Film capacitors in this circuit are not expensive, (I use Wima FKP).
Alex.
P.S. And of course - DO NOT OMIT the output resistors (i.e. - use RCR, not RC!), if you have a cables >10-15cm length.
This was possible 30-40 years ago, but not now.
About this.
Of course, the cost itself is not reduced much, but it is simpler and reduces the path from a short-circuited path in parallel to a single path with a 100 ohm resistor.
Is it because of impedance matching, and the performance of modern DACs that has gotten so good that it's necessary?
@jean-paul
if there is no output signal and no offset, it would be meaningless. But I am building my first DAC and it is in the prototype stage, so I am going to approach it carefully. I am a noob. Thank you for the good method.
if there is no output signal and no offset, it would be meaningless. But I am building my first DAC and it is in the prototype stage, so I am going to approach it carefully. I am a noob. Thank you for the good method.
With no output signal and no offset nothing will happen.
You spoke of short circuit current but there is no short circuit. There is a possible + or - rail voltage appearing as DC offset at the opamps outputs at power on/off that need to be muted normally via 47 to 100 Ohm to limit current to acceptable levels to GND. The resistors also function as protection against capacitive loads like cables. So called "power on/off muting" to prevent the plops. The plops are translated to a pulse of DC offset voltage that gets amplified in the amplifier multiplied by its gain. This is perceived as annoying loud plops/farts and sometimes even possibly damaging to loudspeakers.
Today RF is around you everywhere, you are even building a device that possibly spits out RF and otherwise it will be your LED lighting, bluetooth, wireless, DECT, SMPS (one of the worst!), cell phone and what not spitting out RF. RF that likes to walk around and enter your devices via its cabling. For that the RCR network functions with triple functions.
I can not express it better in English, sorry.
You spoke of short circuit current but there is no short circuit. There is a possible + or - rail voltage appearing as DC offset at the opamps outputs at power on/off that need to be muted normally via 47 to 100 Ohm to limit current to acceptable levels to GND. The resistors also function as protection against capacitive loads like cables. So called "power on/off muting" to prevent the plops. The plops are translated to a pulse of DC offset voltage that gets amplified in the amplifier multiplied by its gain. This is perceived as annoying loud plops/farts and sometimes even possibly damaging to loudspeakers.
Today RF is around you everywhere, you are even building a device that possibly spits out RF and otherwise it will be your LED lighting, bluetooth, wireless, DECT, SMPS (one of the worst!), cell phone and what not spitting out RF. RF that likes to walk around and enter your devices via its cabling. For that the RCR network functions with triple functions.
I can not express it better in English, sorry.
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@jean-paul
Yes, that's right. I've previously simulated the entire circuit with the boost converter and OPAMP, and there was a peak of about 9mV at startup. However, I was able to reduce it to very low by sequencing the V+/V- supplies.
Some opamps require the negative voltage to be supplied first, others require the positive voltage to be supplied first. And discretes have a larger offset
Yes, that's right. I've previously simulated the entire circuit with the boost converter and OPAMP, and there was a peak of about 9mV at startup. However, I was able to reduce it to very low by sequencing the V+/V- supplies.
Some opamps require the negative voltage to be supplied first, others require the positive voltage to be supplied first. And discretes have a larger offset
Still a simple micro relay shorting unbalanced outputs of both channels to GND or balanced outputs to each other will guarantee 100% silence and 0.000V DC. No simulation or sequencing necessary, simpler, cheaper, more reliable and as a present a reduction to absolute zero plops. Great invention!
I never simulated anything but in reality the plops are just not what you want or like. Good devices are silent except when playing back music.
Now just imagine you would leave the external/multi box approach with all the added RF and interface risks and build just 1 well shielded device 🙂
I never simulated anything but in reality the plops are just not what you want or like. Good devices are silent except when playing back music.
Now just imagine you would leave the external/multi box approach with all the added RF and interface risks and build just 1 well shielded device 🙂
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No.
Because High Frequency radiation to the cable (this signal enter to OP output and feedback, and may increase it's noise and THD).
Simple RC circuit at the OP's output is to avoid oscillations on the capacitive load (R is enough, but C in the DACs additionally filter HighFreq from OP).
But RCR is bidrectional, and also act as a low pass filter against RF.
Alex.
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From better double than nothing to better triple than double 🙂 :
- Simple R at the opamps output is to avoid oscillations because of the capacitive load.
- Simple RC at the opamps output is avoid oscillations because of the capacitive load and to avoid RF by DAC to go to output.
- Simple RCR at the opamps output is to avoid oscillations because of the capacitive load, to avoid RF by DAC to go to output and to avoid stray in of outside RF via cabling.
DAC people, probably the most pleasant people at parties 😀
- Simple R at the opamps output is to avoid oscillations because of the capacitive load.
- Simple RC at the opamps output is avoid oscillations because of the capacitive load and to avoid RF by DAC to go to output.
- Simple RCR at the opamps output is to avoid oscillations because of the capacitive load, to avoid RF by DAC to go to output and to avoid stray in of outside RF via cabling.
DAC people, probably the most pleasant people at parties 😀
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