Master thread on building an affordable and high performing audio analyzer utilizing the E1DA Cosmos ADCiso (crowd sourced)

[Mulder]

I have two questions that would be great if they where covered here.
1. What is the consequences and limitations of the impedance/voltage settings.
2. How to measure power-amplifiers? Do this require a dummy load and in that case, how to build and connect it?

 

[sseppala]

1. What is the consequences and limitations of the impedance/voltage settings.
2. How to measure power-amplifiers? Do this require a dummy load and in that case, how to build and connect it?

2.
Here is an excelent web page detailing of how to make amplifier measurements with E1DA Cosmos ADC
https://www.openaudiolab.com/measuring-amps/

It is really informative that at first the author was taking measurements just one channel loaded and got much better results than Amir. Then he swiched to measuring both channels loaded at the same time and basically got the same results as Amir.

Edit: Thing that I am a little buzzled about the openaudiolab guide is the usage of of the lowpass filter. To me it sound like cheating or unnecessary to get better measurements. Would it not be possible/better to solve this by averaging multiple measurements. I would love if someone more knowledgeable could comment on this.

Here is also the ASR dummy load configuration -thread.

 

[somebodyelse]

As an adjunct to this great thread; should some kind of a shared-depository be created?
For a compendium of various audio test signals/tracks/tones/sweeps, in different analog/digital audio formats, w/such files being royalty and license-free.

@restorer-john' post "SOS Magazine Test Files" is a good start.

https://www.audiosciencereview.com/...to-sox-audio-tool-as-a-signal-generator.4242/

 

[Mulder]

2.
Here is an excelent web page detailing of how to make amplifier measurements with E1DA Cosmos ADC
https://www.openaudiolab.com/measuring-amps/

It is really informative that at first the author was taking measurements just one channel loaded and got much better results than Amir. Then he swiched to measuring both channels loaded at the same time and basically got the same results as Amir.

Edit: Thing that I am a little buzzled about the openaudiolab guide is the usage of of the lowpass filter. To me it sound like cheating or unnecessary to get better measurements. Would it not be possible/better to solve this by averaging multiple measurements. I would love if someone more knowledgeable could comment on this.

Here is also the ASR dummy load configuration -thread.

Yes, I know about this site. My point is that if the goal of the first post in this thread is to summarize how to utilize the E1DA Cosmos, like a HOWTO, then I think it has to contain information about how to measure power-amps. OP have to consider if it also ought to have a collection of links.

​

 

[restorer-john]

Here is an excelent web page detailing of how to make amplifier measurements with E1DA Cosmos ADC
https://www.openaudiolab.com/measuring-amps/

It is good except for the following which is plain incorrect:

BTL amplifiers DO NOT share grounds, nor does the "-" (negative) speaker terminal connect to GND.

 

[Sokel]

It is good except for the following which is plain incorrect:

View attachment 363891

BTL amplifiers DO NOT share grounds, nor does the "-" (negative) speaker terminal connect to GND.

Some make it clear about it:

 

[Roland68]

It is good except for the following which is plain incorrect:

View attachment 363891

BTL amplifiers DO NOT share grounds, nor does the "-" (negative) speaker terminal connect to GND.

Oh yes, @restorer-john is absolutely right.
You should be very careful what you connect. This applies to a purchased or self-made dummy load as well as, for example, additional protection circuits (relay or SSR) for speakers. There could be a connection from speaker minus to device ground or network ground.