Hi, everyone.
After reading many posts and articles on diyAudio, I became unbearably curious and just signed up and now I'm writing a post here.
I don't have much knowledge about digital or analog electronic circuits, so even if my question is basically wrong or stupid, I appreciate your understanding.
I am designing an all-in-one system with an input channel selector, a preamplifier, and a few more features using the TDA7292, PGA2311, and ATmega328PB processor.
At first, I tried to use the method of selecting the line in channel using the signal relay and controlling the volume using the analog potentiometer of Alps Alpine. All systems except volume control are controlled by the main processor.
But I soon realized that it (Alps' analog potentiometer) isn't very good in terms of cost, production, and quality, and now I'm trying to use TI's PGA2311 to control the line in volume.
One PGA2311 chipset is responsible for one line input, and multiple PGA2311 chipsets are installed on the PCB as many as the desired number of line inputs.
The idea was that when switching line input modes, one PGA2311 chipset would slowly attenuate the output to 0%, while the other PGA2311 chipset would slowly increase the volume of the other line input, resulting in what would appear to the user as a smooth transition between the line inputs.
Since the PGA2311 is used as a line input selector, the Lout+, Lout-, Rout+, and Rout- pins of each chip are shared as one. (The audio grounds of L and R are separated to use differential line input.)
Because the PGA2311 can mute line inputs, I thought that using multiple PGA2311s would allow me to control as many line inputs as I wanted, so I removed the line input selector circuit(using signal relays) that I had painstakingly designed at first.
However, while looking for some resources on Google to program the PGA2311, I found a line input channel selector designed by someone. The channel selector that I found was still using a relay to switch the line input despite having a built-in PGA2311 chip.
Suddenly, I became anxious that the direction I was designing might be wrong.
So I referred to many posts and searched for many products sold on the Internet. but what they have in common is that they use a relay as an input channel selector.
This is where my question arose: While PGA2311 has a MUTE function, but why use a relay to configure the input channel selector?
Or is my idea fine in theory and just a matter of personal preference?
The first thing I can guess is... the cost problem of the PGA2311, which I am most comfortable with.
Since the number of line inputs is about 3, which is not that many, I think it is worth investing in 3 PGA2311 chips if it is simply a matter of cost.
Also signal relays use physical contacts, their switching speed is slow, and they can wear out or oxidize, so I don't want to use them if possible.
But I think I may be wrong.
Are there other issues besides cost? I think there could be other reasons such as interference by electrical signals, problems with matching impedance, problems with programming pins, etc...
Please let me know your opinion.
Thank you.
After reading many posts and articles on diyAudio, I became unbearably curious and just signed up and now I'm writing a post here.
I don't have much knowledge about digital or analog electronic circuits, so even if my question is basically wrong or stupid, I appreciate your understanding.
I am designing an all-in-one system with an input channel selector, a preamplifier, and a few more features using the TDA7292, PGA2311, and ATmega328PB processor.
At first, I tried to use the method of selecting the line in channel using the signal relay and controlling the volume using the analog potentiometer of Alps Alpine. All systems except volume control are controlled by the main processor.
But I soon realized that it (Alps' analog potentiometer) isn't very good in terms of cost, production, and quality, and now I'm trying to use TI's PGA2311 to control the line in volume.
One PGA2311 chipset is responsible for one line input, and multiple PGA2311 chipsets are installed on the PCB as many as the desired number of line inputs.
The idea was that when switching line input modes, one PGA2311 chipset would slowly attenuate the output to 0%, while the other PGA2311 chipset would slowly increase the volume of the other line input, resulting in what would appear to the user as a smooth transition between the line inputs.
Since the PGA2311 is used as a line input selector, the Lout+, Lout-, Rout+, and Rout- pins of each chip are shared as one. (The audio grounds of L and R are separated to use differential line input.)
Because the PGA2311 can mute line inputs, I thought that using multiple PGA2311s would allow me to control as many line inputs as I wanted, so I removed the line input selector circuit(using signal relays) that I had painstakingly designed at first.
However, while looking for some resources on Google to program the PGA2311, I found a line input channel selector designed by someone. The channel selector that I found was still using a relay to switch the line input despite having a built-in PGA2311 chip.
Suddenly, I became anxious that the direction I was designing might be wrong.
So I referred to many posts and searched for many products sold on the Internet. but what they have in common is that they use a relay as an input channel selector.
This is where my question arose: While PGA2311 has a MUTE function, but why use a relay to configure the input channel selector?
Or is my idea fine in theory and just a matter of personal preference?
The first thing I can guess is... the cost problem of the PGA2311, which I am most comfortable with.
Since the number of line inputs is about 3, which is not that many, I think it is worth investing in 3 PGA2311 chips if it is simply a matter of cost.
Also signal relays use physical contacts, their switching speed is slow, and they can wear out or oxidize, so I don't want to use them if possible.
But I think I may be wrong.
Are there other issues besides cost? I think there could be other reasons such as interference by electrical signals, problems with matching impedance, problems with programming pins, etc...
Please let me know your opinion.
Thank you.
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A very interesting approach.
One thing to bear in mind - the behavior of the PGA2311 for
software mute vs hardware mute is different
https://e2e.ti.com/support/audio-group/audio/f/audio-forum/444421/pga2311-fault-with-the-muting
One thing to bear in mind - the behavior of the PGA2311 for
software mute vs hardware mute is different
https://e2e.ti.com/support/audio-group/audio/f/audio-forum/444421/pga2311-fault-with-the-muting
I guess the simple answer is that relays are cheaper, simpler and take up less board space than what you propose. Remember that DIY-projects where you don't really care about cost is not what something like a PGA2311 was designed for.
Also, as I understand what you want to get out of this you would be able to accomplish the same thing with a single chip and maybe a bit more complexity in SW. However, moving complexity from the HW to the SW is something that would make a lot of sense for a high-volume application, so this also looks like a good deal if you are a manufacturer 🙂
Also, as I understand what you want to get out of this you would be able to accomplish the same thing with a single chip and maybe a bit more complexity in SW. However, moving complexity from the HW to the SW is something that would make a lot of sense for a high-volume application, so this also looks like a good deal if you are a manufacturer 🙂
So it can mute its outputs but what about the impedance situation on the "summing bus"? What happens to the output impedance when one mute? What does the other ones experience in different scenarios?
//
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-- To quadtech and Nisbeth --
Thanks for the reply.
I have not been trained in electronic circuit engineering professionally, nor am I a corporate official. However, I would like to design a circuit that can be recognized as a 'product' on the market and see if it has value as a commercial product.
Therefore, if the designed circuit passes appropriate tests, I will try to produce it in small quantities, but not in large quantities.
Still I haven't found a definitive answer to this question yet, so I'm still debating whether to use relay control or parallel-multiple PGA2311 control.
However, in the risky current situation, I feel that a signal relay might be more appropriate.
Of course, the Click relay sound when switching line inputs may be unpleasant for some users.
But I don't have enough time and money to test this 'PGA2311 line input selector' theory... It takes too much time and money to manufacture a demo board.
+ In addition, I realized a while ago that the PGA2311 was designed to handle single ended signals, not a balanced line signals. It was my fault for thinking that differential line input would be possible...
Now I've changed the circuit itself back to single ended, and the PGA2311 should work fine with an unbalanced input like a headphone jack or RCA terminal.
Thanks for the reply.
I have not been trained in electronic circuit engineering professionally, nor am I a corporate official. However, I would like to design a circuit that can be recognized as a 'product' on the market and see if it has value as a commercial product.
Therefore, if the designed circuit passes appropriate tests, I will try to produce it in small quantities, but not in large quantities.
Still I haven't found a definitive answer to this question yet, so I'm still debating whether to use relay control or parallel-multiple PGA2311 control.
However, in the risky current situation, I feel that a signal relay might be more appropriate.
Of course, the Click relay sound when switching line inputs may be unpleasant for some users.
But I don't have enough time and money to test this 'PGA2311 line input selector' theory... It takes too much time and money to manufacture a demo board.
+ In addition, I realized a while ago that the PGA2311 was designed to handle single ended signals, not a balanced line signals. It was my fault for thinking that differential line input would be possible...
Now I've changed the circuit itself back to single ended, and the PGA2311 should work fine with an unbalanced input like a headphone jack or RCA terminal.
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FWIW, If you honestly don't believe you have the time or the money to make a prototype board before you launching something that should be a commercial product - especially one with both HW and SW in it - then I would definitely advise you to drop it because that to me is borderline delusional.
You may well be far cleverer than I am and have far more luck, but if you look at my personal blog (link under my profile) and count the number of designs that I have published over 10 years, then I'll tell you that the percentage of those that worked as intended on the first attempt is not very high. To add insult to injury I only show the stuff that eventually worked - the really abject failures I couldn't save typically don't even make it to a mention on the blog so the real success rate is far lower.
Also, if you don't care about my experiences you can read from someone who has actually done it what it really takes to design and launch commercial audio products, then look no further than the blog series by Jason Stoddard of Schiit Audio over here: https://www.head-fi.org/threads/sch...f-the-worlds-most-improbable-start-up.701900/ This is someone with the right education and years of relevant experience in the business and there's still more false starts and dead ends than you care to count...
You may well be far cleverer than I am and have far more luck, but if you look at my personal blog (link under my profile) and count the number of designs that I have published over 10 years, then I'll tell you that the percentage of those that worked as intended on the first attempt is not very high. To add insult to injury I only show the stuff that eventually worked - the really abject failures I couldn't save typically don't even make it to a mention on the blog so the real success rate is far lower.
Also, if you don't care about my experiences you can read from someone who has actually done it what it really takes to design and launch commercial audio products, then look no further than the blog series by Jason Stoddard of Schiit Audio over here: https://www.head-fi.org/threads/sch...f-the-worlds-most-improbable-start-up.701900/ This is someone with the right education and years of relevant experience in the business and there's still more false starts and dead ends than you care to count...
Sorry for the frivolous answer.
In fact, saying that I don't have time was closer to personal greed for me.
I honestly think there are some problems with finances. Because I'm still a student and I don't have that much money to manage on my own.
But because of the pressure of having to earn whatever money I can within a few years, I wanted to see how far I could go with what I was doing as a hobby.
So it may not be enough, but I try to improve my knowledge little by little by searching Google for what I want to find every day.
Thanks for the realistic advice, I'll take some time to think for myself.
In fact, saying that I don't have time was closer to personal greed for me.
I honestly think there are some problems with finances. Because I'm still a student and I don't have that much money to manage on my own.
But because of the pressure of having to earn whatever money I can within a few years, I wanted to see how far I could go with what I was doing as a hobby.
So it may not be enough, but I try to improve my knowledge little by little by searching Google for what I want to find every day.
Thanks for the realistic advice, I'll take some time to think for myself.