challenge: record your amplifier voltage and do DeltaWave comparison

[pjug]

Not good results: not so good listening experience. Which is also room dependent.

You won't get your answers by asking such measures, from unknown setups and environments. But by asking a friend to bring an amp in your home, for listening tests... or maybe by changing your environment, or your speakers.

I think you want me to have different goals with this than what I have. For this, I have no concern with sound, only fidelity of electrical signals.

 

[b4nt]

If electrical signals aren't good with your amp, you shall hear it. Especially in such a dynamic track you mentionned.

 

[pjug]

If electrical signals aren't good with your amp, you shall hear it. Especially in such a dynamic track you mentionned.

It sounds good to me. So I gently suggest you help me figure out how to make a better recording of the voltage. Or show me that you can do better indicating that my equipment is not up to snuff.

 

[Helicopter]

Do you record a wav in Audessey and then run it through DW with the source and DW spits out the chart?

How loud do you play it?

 

[pjug]

Do you record a wav in Audessey and then run it through DW with the source and DW spits out the chart?

How loud do you play it?

I was using audacity (maybe an issue?). In the speaker level recording I posted the peaks were >40V out of the amplifier (divided by 67 for recording). I would have to boost the track to get higher since the peaks in the track are something like -4dB and my system is such that 0dB gives 60V RMS, or 85V peak (which may clip).

But if you want to do it yourself, I don't really care about the level I'm more interested (for now) in how good your recording is.

 

[Helicopter]

I was using audacity (maybe an issue?). In the speaker level recording I posted the peaks were >40V out of the amplifier (divided by 67 for recording). I would have to boost the track to get higher since the peaks in the track are something like -4dB and my system is such that 0dB gives 60V RMS, or 85V peak (which may clip).

But if you want to do it yourself, I don't really care about the level I'm more interested (for now) in how good your recording is.

I think Audacity is good for the recording. Hopefully I find time to give it a whirl when everyone is up tomorrow.

 

[Blumlein 88]

I beleive he is willing to see some representative shapes of its amp outputs, driving his speakers.

Comparing captured track shapes and spectrum shapes using DW is a solution?

What is missing, is how audio renders at speakers side, for the listener.

With all due respect, you are first wanting something different than the OP. Also like the other DW thread you are asking for things tested this way and that all willy nilly. You'll flail around and not get anywhere.

Right now the OP wishes to find out the fidelity of the signal at speaker terminals vs the original signal. And he'll need to iron out wrinkles in his measurement procedure to get a good baseline to see what is happening. So first let us help him figure out how to get good DW results, and then in some specific way test for rather specific things. The suggestion to try other amps/speakers is a good one, but not before he has a good measurement protocol.

 

[b4nt]

Or show me that you can do better indicating that my equipment is not up to snuff.

I beleive speakers are voltage driven. So if the electrical signals/recording shapes are correct, I assume you won't get much from another amp.

Some amps power supplies being too weak on high loads, not being able to drive the meds/subs. Or not fast enough on attacks (fast voltages changes).

I assume you will see this more with Audacity recordings, checking curves.

 

[Blumlein 88]

I was using audacity (maybe an issue?). In the speaker level recording I posted the peaks were >40V out of the amplifier (divided by 67 for recording). I would have to boost the track to get higher since the peaks in the track are something like -4dB and my system is such that 0dB gives 60V RMS, or 85V peak (which may clip).

But if you want to do it yourself, I don't really care about the level I'm more interested (for now) in how good your recording is.

Did the Behringer come with a DAW program? If so use that to record. If not download Reaper which is free to try, and record with it. If you are using Windows using a DAW to record lets you interface with the ADC via ASIO. That will give good reliable results. Audacity can't use ASIO because it is propriatary. If you are recording with a Mac then Audacity will be alright.

https://www.reaper.fm/ A little bit of a learning curve, but for just recording it won't be too involved.

 

[Blumlein 88]

What are we doing here?

I understand the recording you made, and I am set up to make similar recordings, but I am puzzled by the charts and I am not familiar with DW.

Is the recording mono or stereo?

Is the chart showing the whole song with no time axis?

Is the chart showimg the recording you made or the null of that recording and the original?

What is the point? To evaluate amp performance under speaker load?

If so, how is this useful?

https://deltaw.org/ You can get it for free here if you think it useful. Pkane one of our members here wrote it. It is a nulling program. Use the original recording as a reference and null it against the recorded file for comparison. Deltawave does a lot of housekeeping for you to make it work well.

The main number along the bottom in the results page is Difference (rms) imo. It is how deep the null is. A null depth of -120 db would be effectively perfect as it means everything is the same down to the level of thermal noise. You are comparing either the right or the left channel as you choose. There are actually many charts to choose from for different purposes.

 

[Blumlein 88]

The specs of the UCA202 are pretty mediocre. You might be somewhat limited by the ADC.

In any case using what you have already run the match on the recorded file. First go into settings of Deltawave (click on the gear symbol in the upper right corner). It will open a page with lots of settings to monkey with. In this case look at the lower left corner. Click Level EQ and next to it Phase EQ. Close the window. Run your comparison. DW will now correct frequency response errors, and phase errors. Sometimes this will improve the null results considerably. If so this tells you the main problems with a better null are simply FR and phase effects. Which aren't anything exotic.

Also Deltawave works best with 2 to 3 minutes of a track to work with. It will even usually work pretty well with 1 minute. I don't know how long a recording you made, but get it a bit over 2 minutes for future testing.

 

[b4nt]

https://deltaw.org/ You can get it for free here if you think it useful.

I'm sure it is usefull. This is also why I was so interested in that other topic. Up to hooking a recorder to two of my DACs.

Now see the last picture I added there, in the other topic. DW can be a tool to point to track sections where the amp/signal is weak. As a next step, I would use my oscilloscope, what I already did, to see what is going on there with signals, at precise time stamps.

Not having an oscilloscope, a cheap 20-20k ADC is an acceptable alternative. Tools (including DW) being so complementary.

 

[pjug]

The specs of the UCA202 are pretty mediocre. You might be somewhat limited by the ADC.

In any case using what you have already run the match on the recorded file. First go into settings of Deltawave (click on the gear symbol in the upper right corner). It will open a page with lots of settings to monkey with. In this case look at the lower left corner. Click Level EQ and next to it Phase EQ. Close the window. Run your comparison. DW will now correct frequency response errors, and phase errors. Sometimes this will improve the null results considerably. If so this tells you the main problems with a better null are simply FR and phase effects. Which aren't anything exotic.

Also Deltawave works best with 2 to 3 minutes of a track to work with. It will even usually work pretty well with 1 minute. I don't know how long a recording you made, but get it a bit over 2 minutes for future testing.

Thanks for all the suggestions. I will try Reaper. Unfortunately I can't do it today, hopefully tomorrow. On the speaker test I only used one minute of recording because it was pretty loud. Maybe I'll go a little longer next time.

 

[pjug]

The specs of the UCA202 are pretty mediocre. You might be somewhat limited by the ADC.

In any case using what you have already run the match on the recorded file. First go into settings of Deltawave (click on the gear symbol in the upper right corner). It will open a page with lots of settings to monkey with. In this case look at the lower left corner. Click Level EQ and next to it Phase EQ. Close the window. Run your comparison. DW will now correct frequency response errors, and phase errors. Sometimes this will improve the null results considerably. If so this tells you the main problems with a better null are simply FR and phase effects. Which aren't anything exotic.

Also Deltawave works best with 2 to 3 minutes of a track to work with. It will even usually work pretty well with 1 minute. I don't know how long a recording you made, but get it a bit over 2 minutes for future testing.

I think there are definitely problems with even the recording of the DAC output. Zooming in shows some poor tracking. I will have to chase whether this is recording software, the ADC (overloading?, edit: ADC has 1.26V max input , this is peak level max correct? Maybe I exceeded this), or maybe it is something else. Again, this is the line level recording, not the recording of the power amplifier output:

 

[Helicopter]

Woof. This is harder than it should be. I think I want a motorless computer. The dry run I did in Audacity with my SET amp and 2i2 has audible HDD noise.

 

[pjug]

Woof. This is harder than it should be. I think I want a motorless computer. The dry run I did in Audacity with my SET amp and 2i2 has audible HDD noise.

Interesting. I happened to be recording with a SSD laptop so maybe that's a good thing. But still your attempt goes to show that it is easy to get interference. I was thinking of using a macbook I have so that Audacity will work better, but that one has a hard disk drive. So instead I will go with trying Reaper on the SSD Windows laptop for my next go at this.

 

[restorer-john]

I am using the track Tricycle by Flim and the BB's available here for $1.29: https://us.7digital.com/artist/flim-and-the-bbs/release/tricycle-11282941
This because of this track's extreme crest factor that allows sending large voltage peaks into real speakers while not blowing you out of the room.

The original was recorded on a Mitsubishi X-80 16bit running at 50.4KHz. They really have no business selling 24bit 88.kHz FLACs.

 

[pjug]

The original was recorded on a Mitsubishi X-80 16bit running at 50.4KHz. They really have no business selling 24bit 88.kHz FLACs.

Very true. I chose this because of the crest factor. Anyway my ADC only does up to 48KHz sampling so I don't really care if it is real hi-res or not.

 

[restorer-john]

Very true. I chose this because of the crest factor. Anyway my ADC only does up to 48KHz sampling so I don't really care if it is real hi-res or not.

I've got the original DMP CD. (Distributed by Telarc International back then)

It would be interesting to compare the actual track/s themselves to see what exactly you are getting as compared to the original.

 

[pjug]

I've got the original DMP CD. (Distributed by Telarc International back then)

It would be interesting to compare the actual track/s themselves to see what exactly you are getting as compared to the original.

Hold on a second and I'll put up the spectrum if you want to eyeball it.... Here it is, traces are L and R: