Beta Test: Multitone Loopback Analyzer software

[Skezza]

Sorry, but something is still clipping. Maybe the ADC input is too hot. What this spectrum represents is a nice square wave, rather than a sine wave with a few distortions. You can see what this really looks like on the Waveform tab and you can use the mouse wheel to zoom in on any portion to see the actual wave form.

OK. I'll try again but take down the input some more. There's a gain knob on this one, so I could turn that down completely.

So, is this?
View attachment 353244View attachment 353251

Couldn't find any specs,however TL is good down to -105db THD+N and it's not it's weak link as it seems.

Before you measure:
Kill all gain,in and out (by the knob or any app using it)
Kill all effects and stuff.
If it's input is unbalanced use a short RCA to unbal jack for the loopback.
Use 48000Khz sampling rate as it seems is it's limit.

I've ordered a short RCA to unbalanced jack I thought i had one in the garage... I do not. I do have an RCA adapter which I'm trying. Will post the results in a bit.

Doing some further experimenting tonight. Feel like I'm learning quite a bit

That is indeed, the interface I've modified. I've done a teardown and have various photos of the guts and the mod. I've also torn down a UX2 and there's a lot of similarity, including TL072's, despite this one being marketed as a cheap guitar practice tool and the UX2 as a more home studio / pseudo-professional product.

I suspect if I can get to a point where I can test both signals fairly, there's almost no difference between a GuitarPort and UX2....

 

[Skezza]

I think I'm getting closer....

 

[Sokel]

I think I'm getting closer....
View attachment 353367

Close but still quite high.
With the settings as it is now,do a level sweep starting at -30 up to -5db and post the results.
Choose Noise and TDH+N on the sweep panel.

 

[Skezza]

Close but still quite high.
With the settings as it is now,do a level sweep starting at -30 up to -5db and post the results.
Choose Noise and TDH+N on the sweep panel.

Awesome. Will give it a go now.

Although I'll admit to being a total n00b about this stuff, I'm wondering if this comes back to a voltage / impedance thing like I first wondered. The headphone output is boosted right? It's not line level. My old soundcard used to have a line level out, but there's no chance this one on my current PC does. I think RCA is line level, but i'm also sticking it through this adapter which is possibly screwing with it. Need that RCA to 1/4 jack I suspect i've got half a dozen adapters somewhere, just not to hand


Edit:
Just had an actual good idea!!
The Toneport has Line level 1/4 out jacks. Can't believe I didn't think of this sooner. brb

 

[Sokel]

Awesome. Will give it a go now.

Although I'll admit to being a total n00b about this stuff, I'm wondering if this comes back to a voltage / impedance thing like I first wondered. The headphone output is boosted right? It's not line level. My old soundcard used to have a line level out, but there's no chance this one on my current PC does. I think RCA is line level, but i'm also sticking it through this adapter which is possibly screwing with it. Need that RCA to 1/4 jack I suspect i've got half a dozen adapters somewhere, just not to hand


Edit:
Just had an actual good idea!!
The Toneport has Line level 1/4 out jacks. Can't believe I didn't think of this sooner. brb

The input is an instrument input,right?
That means that is waiting for a few mV.
Line outs reach 2 V and headphone output even higher.

So start with that few.
A sweep level will now show you the sweet spot,start really low,even at -60db.

(a few months ago I started on this thread just like you,I'm still a newbie but this app and the people here can get you at the next level! )

 

[Skezza]

So looks like you're right... using a Line output from the left channel of the Toneport didn't make much difference at all. If anything, it seems to have made things worse.

Assuming I've done things correctly, this is my level sweep

Test setup is definitely janky.


Also, appreciate the feedback about the fact you were in a similar boat. We all have to start somewhere and if nobody was willing to help, well nobody else would learn!

just realized I'm missing noise off the measurement as you suggested, so redoing.

 

[Sokel]

just realized I'm missing noise off the measurement as you suggested, so redoing.

Next time you don't need to redo,just choosing it from the drop-down menu and it will appear in the same chart.
But you should redo it,there's something wrong there with THD+N jumping around,probably something around there is injecting noise?
Let's see.

It should do something like this but not as good as the DAC he's using there.

Beta Test: Multitone Loopback Analyzer software

I just started playing with this tool. I hope to pick up some of the Cosmos gear and USB isolator, but I thought I could work on getting my noise floor cleaned up first. I think I saw some guides for tweaking windows (10) settings somewhere but it might have been a different thread. Anyway I've...

www.audiosciencereview.com

But you get the point,it should decline smoothly until the point it's input won't like it and the trace will go up again.

 

[Skezza]

Next time you don't need to redo,just choosing it from the drop-down menu and it will appear in the same chart.
But you should redo it,there's something wrong there with THD+N jumping around,probably something around there is injecting noise?
Let's see.

It should do something like this but not as good as the DAC he's using there.

Beta Test: Multitone Loopback Analyzer software

I just started playing with this tool. I hope to pick up some of the Cosmos gear and USB isolator, but I thought I could work on getting my noise floor cleaned up first. I think I saw some guides for tweaking windows (10) settings somewhere but it might have been a different thread. Anyway I've...

www.audiosciencereview.com

But you get the point,it should decline smoothly until the point it's input won't like it and the trace will go up again.

Yeah, so they look nothing alike do they.... hmmm.

Let me switch back to the GuitarPort only. Perhaps because I'm using two devices the drivers aren't playing nice...

 

[Skezza]

Tweaked some of the ASIO config settings, slightly better, but still a bit weird looking!

Edit:

Tweaked some more.... this seems to look okay?

 

[pkane]

Tweaked some of the ASIO config settings, slightly better, but still a bit weird looking!

View attachment 353391

Edit:

Tweaked some more.... this seems to look okay?
View attachment 353392

Last one looks much better. Looks like around -7dBFS play gain is the maximum where you get the best performance. Higher than that leads to a rapidly increasing error, likely clipping.

Try doing a frequency sweep at around -7dBFS play gain setting. Let's see what that looks like.

 

[Skezza]

 

[pkane]

View attachment 353393

View attachment 353394

I think you're getting some better results now. Looks like noise is pretty consistent with level, staying lower than -90dB, and harmonic distortion, along with THD+N goes to around -71dB, which isn't great by modern standards, but isn't going to be very awful.

Now, you can try to measure frequency response. In case you didn't know, you can select some automatic pre-sets for the desired measurements at the top right (just adjust levels and frequency ranges after you pick a preset to match your device capability). Start with Sweep THD vs Frequency. You can also try Frequency Response (log-chirp).

 

[Rantapossu]

I know it's too soon to have another version, but here is a minor enhancement I wanted to add a while back, recently requested by a user:

Preview version 1.1.7: https://app.box.com/s/ue7ll9xmvwogst817x2l1xg09opvgy47

Only one change to allow level sweeps to plot against measured or generated levels on the X-axis. Previously, only the measured level was plotted. With version 1.1.7 you can switch freely between the two (measured is the default). Notice the X-axis label and values:

View attachment 352690

View attachment 352691

Hi @pkane !

The "Show Measured level" -option gives an error message every time I change the mode:

It still changes the mode after I press the "OK" -button and the actual feature works ok too when sweeping, so it's only a cosmetic thing.

The feature itself is a killer! Thanks!

 

[Sokel]

Hi @pkane !

The "Show Measured level" -option gives an error message every time I change the mode:

View attachment 353544

It still changes the mode after I press the "OK" -button and the actual feature works ok too when sweeping, so it's only a cosmetic thing.

The feature itself is a killer! Thanks!

Did the same to me and I thought it's the way it works,

 

[pkane]

Hi @pkane !

The "Show Measured level" -option gives an error message every time I change the mode:

View attachment 353544

It still changes the mode after I press the "OK" -button and the actual feature works ok too when sweeping, so it's only a cosmetic thing.

The feature itself is a killer! Thanks!

Hmm. Does it do that once you have a sweep result or only when the plot is blank?

 

[Rantapossu]

Hmm. Does it do that once you have a sweep result or only when the plot is blank?

It does it every time I freshly start MTA and before taking any measurements go to the "Level Sweep" -tab to change the mode.

When the sweep is ready, I can toggle the mode without the error message.

It works too if I run a single spectrum measurement first and then go to the "Level Sweep" -tab.

So I guess it doesn't like the blank plot...

 

[Sokel]

Hmm. Does it do that once you have a sweep result or only when the plot is blank?

Does it once in the beginning with a blanc chart.
I just hit measure once and then it works for the whole session.

 

[pkane]

It does it every time I freshly start MTA and before taking any measurements go to the "Level Sweep" -tab to change the mode.

When the sweep is ready, I can toggle the mode without the error message.

It works too if I run a single spectrum measurement first and then go to the "Level Sweep" -tab.

So I guess it doesn't like the blank plot...

OK, that should be easy to track down, then, thanks for testing!

 

[pkane]

Easy enough The "Property not valid" error message when switching Measured/Generated setting on a blank sweep should no longer show:

https://app.box.com/s/ue7ll9xmvwogst817x2l1xg09opvgy47

@Rantapossu, @Sokel, please check.

 

[Rantapossu]

Easy enough The "Property not valid" error message when switching Measured/Generated setting on a blank sweep should no longer show:

https://app.box.com/s/ue7ll9xmvwogst817x2l1xg09opvgy47

@Rantapossu, @Sokel, please check.

Thanks again!

Works as expected!