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Looking for module to monitor the audio professional power amplifier output

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(@techtautomation)
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Joined: 3 years ago
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Hi,

I have a use case and would like to build a monitor equipment/tool to monitor the audio power amplifier output in runtime. I have professional power amplifiers (let's assume one is mono amplifier with 1000w power which has 2homs, 4 ohms, 100v output and another one is stereo amplifier with 1000W + 1000W which has output where i can connect 2 ohms or 4 ohms or 8 ohms depends on my speaker load).

I would like to a build a component where i would need to connect my amplifier output to this component to monitor the voltage, ampere, wattage, frequencies, ohms etc in run time. (may be frequencies can be displayed in spectrum view). 

 

Could someone please help me whether we have any module (one or many) can be used to achieve this functionality? i see some equipment in market to do this but i would like to build my own so that i can add all the additional feature like bluetooth etc via arduino. 

 

I am new to the electronics but i have some knowledge on IT side. So, please let me know if my post does not make sense or need more information.

Appreciate your responses!..

 

Thanks

 

 

This topic was modified 3 years ago by techtautomation

   
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MadMisha
(@madmisha)
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I have never heard of anything being done at speaker level power. I've worked in the industry for 2 decades and have toured for half that time. Any monitoring would be done at line level. To monitor it at speaker level, you would be taking the signal and reducing it back to line level to evaluate and I really doubt that would actually help you. The power running to a speaker fluctuates constantly and doing this could compromise the audio.

 

The standard way to test for THD is to use a mic. You can compare it on 2(or more) speakers and whatever they have in common is either in the line or the amplifier. You could look at the spectrum on the line to rule that one out.

 

But what is your ultimate goal? RTA mics will give you an idea of the actual result and you can make adjustments based on that. I also cannot think of anything you could change on an amplifier that would make a difference, everything would be changed before the amp. I feel like I'm missing something here.

 

Otherwise, the Nextion displays do have a graph that you can send data to and plots fairly fast and they are easy to program/code with their editor. But I'm not sure how you would get the differential signal into the Arduino.


   
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(@techtautomation)
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Hi @madMisha,

Thank you for quick response.. I am sorry if i haven't explained the requirement very well. Please check the below attachment which may be helpful to explain my expectation. I would like to do the realtime monitoring for these use cases.

Montoring tool use case

There are couple of tools are available in market for RTA.

https://spllabusa.com/products/multifunctional-measuring-devices/next-lcd.html

https://www.audiocontrol.com/pro-audio/dm-rta/

both tools are helping to analyze the speaker level line it seems. But would like to see whether we have option to build this similar tool using some modules.

Thanks again!.


   
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MadMisha
(@madmisha)
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Joined: 4 years ago
Posts: 340
 

I was waiting until I could get to my desktop to reply but that isn't happening any time soon and now this is my second try on my Pi because it crashed after I was almost done.

 

I see now. I spot transformers on the picture and now I notice the 100v in your first post. So this is not pro audio but an install like in ceiling for stores/offices. Big difference. Way back when I did installs for A/V, we really didn't have a need for anything like this and I am still struggling to understand how it would be useful.

 

So, about those two products. I don't think either one being what you really need. Both are meant for Car audio. They can get away with so many things that pro audio and installs cannot(either because of professional practice or building codes) That industry is saturated with so many products that don't do anything useful. I would take their claims of accuracy with a grain of salt. Not that it is unachievable or that they can't deliver, just that I have seen too many false claims, so be careful. The second link , according to the website, cannot handle 100v. When I tried looking for a review on YouTube I found one guy who I'm sure was paid and didn't use it properly nor particularly know what the data actually meant. I originally wrote something pertinent about the first one but now I can't remember. Maybe I'll remember when I no longer feel like throwing this wireless keyboard across the room.

 

But if you are really intent on creating this, I will have to do some thinking and I will probably reply when I get back to my desktop were it is easier to type and look stuff up. Rolling with it now, I'm sure you can use a coil to read DC amps and I believe there are modules for that. It would protect the integrity of the signal but would lack in accuracy. I will have to think about how to get the voltage of a differential pair while getting it down to the level that would be safe for the Arduino and still with a good range.


   
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(@techtautomation)
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Hi @MadMisha,

Thank you vey much again for responding and considering to support for my intention. I understood about your observations regarding the existing tool and thanks for pointing me out this.. I really appreciate your help and very excited to get more information from you about the your thought process to build this. Yes, I still would like to build this tool but i can't even start without expertise support like you. I can provide more information if you would like to hear why i want to build this.

I am really looking forward to see your response.. 

Thanks again!..

 

This post was modified 3 years ago by techtautomation

   
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MadMisha
(@madmisha)
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Joined: 4 years ago
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@techtautomation

So, here is a module that will get you the current. HiLetgo-Current-Ammeter-TA12-100-Arduino B00HGB9RB4 You would need 2(one for each wire).

 

Here is an auto ranging volt meter setup. arduino-autoranging-ac-dc-voltmeter-with-trms You could probably scale it back since you do not need to go to 400 volts. I don't recall ever checking voltage with another speaker currently running so I cannot guarantee it will not affect the audio. Also note that you would need to be playing test tones(sine wave) through it to get a good level. Complex waveforms (normal audio) will be all over the place and won't mean or add up to anything.

 

And obviously watts is just volts x amps.

 

Checking resistance, I'm not sure about that.

 

For the spectrum analyzer, you would need to drop the voltage to an arduino safe level. Here is a tutorial of how to do this at line level(probably consumer line level so -10bB) diy-fft-audio-spectrum-analyzer-ca2926. It's no comparison to Smaart but it should work. On the 100v line you would need a transformer to drop it back down, preferably to what you need here but remember this will consume some of the power and will be like adding part of a speaker on that line.


   
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(@techtautomation)
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Hi @MadMisha,

First of all, I would like to thank for your research and sharing these information quickly. Much appreciated your contribution!.. I am going to look at all the information that you had shared but before doing it, i thought to share my thanks to you!..

I am sure i will come back to you with more basic questions since i am not completely from electronics background but i would do my best to understand the information that you shared.

Thanks.


   
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(@techtautomation)
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Joined: 3 years ago
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Hi @MadMisha,

I went through your thought process and understood as below. Could you please let me know whether my understanding is correct?

 

Tool understanding diagram

Can i use the below sensors (one on each model) to sensor voltage and current? looks like it has capability of sensing till 30A and sensing till 220v, it should be sufficient to measure to some extend initially for my project.

https://www.amazon.com/WayinTop-Current-Voltage-DC0-25V-Terminal/dp/B08BZKPSFY/ref=sr_1_8?crid=PBT9UG8G9P8S&dchild=1&keywords=current+sensor&qid=1615841467&sprefix=current+s%2Caps%2C216&sr=8-8

 

Apart from this, regarding the frequencies display, I looked at the information that you shared and also looked at some documents & video tutorials and got few questions. Can i use any module which would convert speaker level to line level so that it can be used to aurdino the way you suggested?

i just google it to identify the below component to explain my question regarding convert from speaker level to line level. but its not necessary to mean the same.

https://www.crutchfield.com/S-Ba1QMBkWMth/p_142SLC4/Scosche-SLC4-Line-Output-Converter.html?XVINQ=GLX&awkw=75622111225&awat=pla&awnw=g&awcr=47439537505&awdv=c&awug=1015334&gclid=Cj0KCQjwi7yCBhDJARIsAMWFScNjPOf9g21116zYErkcGovqRnJPnhcZm3SGuPxOHmmegUH9RQ_IpMMaAoovEALw_wcB

Please let me know whether we have any similar aurdino acceptable component to convert speaker level to line level (both 100v and/or ohms load using either one component or multiple components).

 

Also, i did google some information regarding the step down transformer that you had mentioned and got some notes saying its called audio frequency isolation transformer (correct me if i am wrong) which would step down the voltage without impacting the frequencies. do we have any such kind of/other transformers (small transformers/modules) to convert what we want?

 

Apart from this, i also got some additional information regarding some ICs called XY splitter or XY divider to calculate the wattage, ohms (impedance) in real time. should we use these ICs or can this be calculated in program itself using the formulas since we have both voltage & current?  if it needs to be calculated using ICs, could you please suggest some suitable ICs for this project?

 

Addition to this, what would be the suitable displays where i can show both frequency spectrum display, voltage, watts, amp, ohms etc.

 

Thanks again for your continuous support and response!.. awaiting for your reply..

 

This post was modified 3 years ago by techtautomation

   
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MadMisha
(@madmisha)
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Joined: 4 years ago
Posts: 340
 
Posted by: @techtautomation

I went through your thought process and understood as below. Could you please let me know whether my understanding is correct?

That's about right but in you would need to decide if you want to measure what the speaker would be getting or the voltage on the 100v line.

 

Posted by: @techtautomation

Can i use the below sensors (one on each model) to sensor voltage and current? looks like it has capability of sensing till 30A and sensing till 220v, it should be sufficient to measure to some extend initially for my project.

I don't know what specific models those are but if that is their rating, then yes. I will note that the current sensor you have there would be inline and that is probably a bad idea. If it fails, it can take your audio system down with it(I actually think this whole thing is a possible point of failure. What we would call a show stopper.). That is why the one I suggested above uses a coil to keep it independent of the system.

 

Posted by: @techtautomation

Apart from this, regarding the frequencies display, I looked at the information that you shared and also looked at some documents & video tutorials and got few questions. Can i use any module which would convert speaker level to line level so that it can be used to aurdino the way you suggested?

Well, yes, kind of. As long as the rated voltage for the input matches what you are patching in and the output puts it close to consumer line level. You can use a potentiometer to fine tune it. Watch out for clipping because that could alter your readings. The one you linked is for car audio and shouldn't be used for 100v systems nor with pro audio systems.

 

Posted by: @techtautomation

Also, i did google some information regarding the step down transformer that you had mentioned and got some notes saying its called audio frequency isolation transformer (correct me if i am wrong) which would step down the voltage without impacting the frequencies. do we have any such kind of/other transformers (small transformers/modules) to convert what we want?

No, an audio frequency isolation transformer is meant to filter out signal that is not supposed to be there, mainly from AC power. A step down transformer just means, using ohms law, it will drop the voltage. You are looking for something like this transformer. Unfortunately, on this one thing, price will matter. Atlas is a very popular here in North America but I believe they also sell to Europe so they should also have 100v transformers. You are not going to find this in an Arduino ready module. This will only bring it down to the level the speaker needs. You would need to drop it down further. Audio transformers are built the way they are for a reason but you might be able to find a transformer that can be tapped closer to what you want but I wouldn't guarantee the audio quality on the other side. Might be close enough though.

Posted by: @techtautomation

Apart from this, i also got some additional information regarding some ICs called XY splitter or XY divider to calculate the wattage, ohms (impedance) in real time. should we use these ICs or can this be calculated in program itself using the formulas since we have both voltage & current?  if it needs to be calculated using ICs, could you please suggest some suitable ICs for this project?

If you are already reading the amperage and volts, all you have to do is multiply those two numbers and you have the wattage. Getting impedance would not be done with audio going to the speaker. Are you trying to find the impedance at the resonance peak? You already have most of the information you need to make the calculation.


   
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(@techtautomation)
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Thanks much again @MadMisha as usual for your quick replay!.. I looked at your response within a hour after you responded but i was waiting to construct the message in a correct way to respond you to ask more questions. but i get lot of dump question within myself and i thought of not posting those questions to you. So i need to do more research to digest your response and come back to you with some valid questions. Please give me some additional time to study more before i back to you..

I have to always do some analysis on my side to understand you response since i am learner 😀  but i know its all part of my learning curve. Happy to learn..

Thank you!...

This post was modified 3 years ago by techtautomation

   
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