Much better to use a relay with NC contacts to short the output.
Relay quality is not important because in "play" mode it's contacts are open.
Alex.
Yes, usually used in reverse polarity.
And the first thing that “tweakers” often do is to remove these mute transistors from the board.
Alex.
Reliable - of course, but all relays are enough reliable at so small current.
Low contact resistance? Sure, but all relays have enough low resistance to do this job.
I use small signal relays from Panasonic(NaIS), Takamisawa, NEC, Omron, because they are small and not expensive.
I mean - these relays don't have to be "audiophile quality" 🙂
Alex.
Low contact resistance? Sure, but all relays have enough low resistance to do this job.
I use small signal relays from Panasonic(NaIS), Takamisawa, NEC, Omron, because they are small and not expensive.
I mean - these relays don't have to be "audiophile quality" 🙂
Alex.
Nonlinear contact resistance at low current density can still let some garbage get to the analog outputs?
Some of the the ones with gold-flashed contacts over silver are reasonably priced, at least seems reasonable to me.
Actually, relay life can be impacted by heat from the coil. That's why Omron sometimes recommends latching relays that only have be pulsed to switch them.
(something that turned up when looking into relay volume control design)
Some of the the ones with gold-flashed contacts over silver are reasonably priced, at least seems reasonable to me.
Actually, relay life can be impacted by heat from the coil. That's why Omron sometimes recommends latching relays that only have be pulsed to switch them.
(something that turned up when looking into relay volume control design)
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Maybe. But only at "Off condition", where there is no sound.
These relays has ~140mW heat from coil, about what you are talking?
Yes, very expensive: NEC UD2 at AliExpress are ~$6.50 for 5pcs, including the shipping to USA.
Long-term, Continuous ON Contacts • Using the Relay in a circuit where the Relay will be ON continuously for long periods (rather than switching) can lead to unstable contacts because the heat generated by the coil itself will affect the insulation and can cause a film to develop on the contact surfaces. We recommend using a latching relay (magnetic-holding relay) in this kind of circuit. If a single-side stable model must be used in this kind of circuit, we recommend adding fail-safe circuits in case the contact fails or the coil burns out.
Quote from https://omronfs.omron.com/en_US/ecb/products/pdf/en-g6k_2f_rf.pdf
This might happened at high ambient temperature.
In fact, I have not encountered or even heard of such a problem in this application (output mute).
Alex.
In fact, I have not encountered or even heard of such a problem in this application (output mute).
Alex.
Yes - best solution is acc to Altor - a short circuit of output by a ON relay which is lifted when output is wanted and thus nothing in series in the signal path. Hopefully the circuit before the short can endure for longer period - perhaps a resistor is needed to limit current but this might let som dirt pass?
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I work in the railway industry and we use relays for critical safety systems. I'm sure your DAC or amp will be fine with using them.
Since relay circuits have been mentioned, are there any that I could implement with this DAC?
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Based on what?
Only on snake oil from audiophile stories.
I want to see a correctly made measurement that shows that distortions and/or noise, or any other important parameter for sound quality, are significantly better without those transistors. In a well-implemented scheme, such a thing cannot be measured.
I also said above in the topic where the real problems are and where it can be modified to have significantly better results. In fact, I don't even think that what I wanted to say was understood.
But here we only discuss audiophile ********, only things like changing a cable with another one 1000 times more expensive because it will surely sound better, putting a selenary stone over the cable to raise the sound to the ninth heaven, etc. Nothing really engineering.
@altor: "This. Resistors 1% or better 0.1%"
Why not with a tolerance of 0.001% and we put what resistor of 0.001% we can find because the exact value is not critical anyway - it only matters that it is 0.001% tolerance.
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Based on what?
Only on snake oil from audiophile stories.
Real engineers know how to measure transistors.
I dont know why you seem so upset - so far this thread as been properly scientific I think. Simmer down, relax, forward sound technical arguments and you will be heard 🙂
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I'm not upset, but you can't say that this thread is properly scientific.
Why am I saying this? Simple and I'll give some information but I won't specify the exact component because related to this I'm really upset by being eliminated from the start any discussion about this solution.
A bipolar transistor specially designed for this task (I will not specify the type) used for muting by short-circuiting the output will be in OFF state in normal operation mode and will present a load of the line only with a capacity compared to GND. This capacity, in the case of the transistor I'm talking about, is specified to be a little over 10pF at under 0.5V voltage and drops to 4pF at 20V. For the normal range of use (0-> ±2V) the capacity variation is only 3-4pF.
Compare this capacity with that presented by a small signal cable that will have a capacity between 50pF and maybe even over 300pF, that is between at least 10 times higher and over 100 times higher. Even only the PCB will be able to present a higher parasitic capacity than this transistor.
Why am I saying this? Simple and I'll give some information but I won't specify the exact component because related to this I'm really upset by being eliminated from the start any discussion about this solution.
A bipolar transistor specially designed for this task (I will not specify the type) used for muting by short-circuiting the output will be in OFF state in normal operation mode and will present a load of the line only with a capacity compared to GND. This capacity, in the case of the transistor I'm talking about, is specified to be a little over 10pF at under 0.5V voltage and drops to 4pF at 20V. For the normal range of use (0-> ±2V) the capacity variation is only 3-4pF.
Compare this capacity with that presented by a small signal cable that will have a capacity between 50pF and maybe even over 300pF, that is between at least 10 times higher and over 100 times higher. Even only the PCB will be able to present a higher parasitic capacity than this transistor.
If you have a circuit idea, why dont you show a schematic? The thread starter even asked for solutions.
Saying A but not B will not grant you any points.
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Saying A but not B will not grant you any points.
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Because 0.1% are mostly used thin film resistors, but 1% are also enough at this place.
Alex.
P.S. There are lot of places in DACs, where <1% resistor are highly recommended, but capacitors are also should be 1% (differential LPF).
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