How to measure the frequency response of a phono preamplifier.

[morillon]

I can't take credit for it, Denon built it in 1983. It puts every phono stage Amir has measured to shame in most areas including a 320mV 1kHz overload...

A-Weighted
View attachment 403151

Unweighted
View attachment 403152

you often talk about it here..but what machine is it?
it corresponds to the period of the swan song of vinyl...
(pra-6000 or 1000?)

 

[Sokel]

Multitone Analyzer has also reverse RIAA modes that can be applied for easy view.
It also has a dedicated LP analysis tab option.

 

[morillon]

Multitone Analyzer has also reverse RIAA modes that can be applied for easy view.
It also has a dedicated LP analysis tab option.

It's a bit me who insisted with pkanes to integrate the functions concerning the lp, as well as the w&f ( can use with tape recorder too).... big thanks to him...

 

[Balle Clorin]

Multitone Analyzer has also reverse RIAA modes that can be applied for easy view.
It also has a dedicated LP analysis tab option.

cannot find the reverse RIAA, please give me a hint.. I have a have wav files I would like to use

It crashes/spins forever when I select RIAA and open a pink noise file, in fact it crashes with sweep or any type of file too
,

 

[Aero]

Thanks for all the replies. This is too complicated.

 

[morillon]

cannot find the reverse RIAA, please give me a hint.. I have a have wav files I would like to use
View attachment 403181

It crashes/spins forever when I select RIAA and open a pink noise file
, View attachment 403188

I don't have a PC in front of me....
but maybe just if I'm a generator(?)( my use) I can talk directly with pkanes in the thread dedicated to his software

Beta Test: Multitone Loopback Analyzer software

This is a software beta-test for IMD and THD aficionados with an intense desire for multi-tone audio testing :) The start of the documentation and the download website is here: https://distortaudio.org/multitone.html (for 64-bit Windows) Multi-tone Analyzer (MA) was more of an experiment than...

www.audiosciencereview.com

 

[Sokel]

cannot find the reverse RIAA, please give me a hint.. I have a have wav files I would like to use
View attachment 403181

It crashes/spins forever when I select RIAA and open a pink noise file, in fact it crashes with sweep or any type of file too
, View attachment 403188

It's the one you have already ticked and by the looks of the measurements above it's already aplied.
Here's how:

Beta Test: Multitone Loopback Analyzer software

no

www.audiosciencereview.com

About the crash,better ask for help in the same thread as morillon says.
Did you try the white periodic noise already at the test signals in MTA?

 

[mfalcon]

What I’m gathering is that my AD/DA that is my computer interface (Lynx Hilo) may or may not be able to provide a low enough input and I have to test. If it can, then I can use the inverse RIAA in REW or Multitone. I don’t know if the test will be of value though because I don’t know about the Lynx Hilo yet so I should probably test that first and create a calibration file.
When I have time to do this I’ll report back if I have any success. I know it would all be better with a proper measurement AD/DA but I’m not there yet. The Quant Analyser though looks pretty cool though

 

[staticV3]

What I’m gathering is that my AD/DA that is my computer interface (Lynx Hilo) may or may not be able to provide a low enough input and I have to test. If it can, then I can use the inverse RIAA in REW or Multitone. I don’t know if the test will be of value though because I don’t know about the Lynx Hilo yet so I should probably test that first and create a calibration file.

It can absolutely provide a low enough output signal to test frequency response and headroom.

The question is if it can maintain a high enough SNR at that signal amplitude to provide meaningful noise and distortion measurements.
Probably not.

 

[Balle Clorin]

About the crash,better ask for help in the same thread as morillon says.
Did you try the white periodic noise already at the test signals in MTA?

No , I am not running DUT devise under test - a loop, just using a previous recorded wav file:.

 

[Balle Clorin]

OK. Here is how I got MultitoneAnalyzer -MA-to do the job

1. Connect PC and USB DAC/ADC with analog Out looped to analog In.
2. MA manual say set volumes to 100%, but with 100% on output and input mic under SOUND in windows the noise and distortion is bad, I used a 1000hz signal in MA and found that 20% in Mic/Input and 50% on Output gave optimal noise and distortion when using -1dB setting PLAY GAIN in MA, To get full frequence range to 22khz I needed so set FFT SIZE at 512k

2. calibration of sound card.
I change preset to Frequency response (log-chirp) and the other yellow marks, and get this, after clicking the red button to run

I then do File/Export measurement/export measurement as text, this let you save calibration file under a name you choose "MA Frequency Response 512k 0Hz-24k at 48k.txt"
Then go to Tools/settings and set the txt file path and name by the Cal button

3. Now you can run a frequency sweep and should get a straight line, if so your setup is calibrated-, And you can put your device to test in the loop. Make sure to adjust Play gain fo avoid clipping( the long time bar becomes red)

4. NOW your can go into Tool/settings and choose RIAA to test a RIAA sweep . That should compensate for a perfect RIAA and show deviation from linearity under the frequency TAB. NOTE 40-60db gain in RIAA so you would need to reduce Play GAIN by 30-50db

5- Since I do not have a RIAA in the loop as I read this, I get a inverse-RIAA like curve instead..when I do a Sweep with RIAA on in settings

 

[morillon]

OK. Here is how I got MultitoneAnalyzer -MA-to do the job

1. Connect PC and USB DAC/ADC with analog Out looped to analog In.
2. MA manual say set volumes to 100%, but with 100% on output and input mic under SOUND in windows the noise and distortion is bad, I used a 1000hz signal in MA and found that 20% in Mic/Input and 50% on Output gave optimal noise and distortion when using -1dB setting PLAY GAIN in MA, To get full frequence range to 22khz I needed so set FFT SIZE at 512k
View attachment 403338
2. calibration of sound card.
I change preset to Frequency response 8log-chirp) and the other yellow marks, and get this, after clicking the red button to run
View attachment 403340

I then do File/Export measurement/export measurement as text, this let you save calibration file under a name you choose "MA Frequency Response 512k 0Hz-24k at 48k.txt"
Then go to Tools/settings and set the txt file path and name by the Cal button
View attachment 403356


3. Now you can run a frequency sweep and should get a straight line, if so your setup is calibrated-, An you can put your device to test in the loop. Make sure to adjust Play gain fo avoid clipping( the long time bar becomes red)
View attachment 403378


4. NOW your can go into Tool/settings and choose RIAA ti test a RIAA sweep . That should compensate for a perfect RIAA and show deviation from linearity under the frequency TAB. NOTE 40-60db gain in RIAA so you would need to reduce Play GAIN by 30-50db

View attachment 403394


5- Since I do not have a RIAA in the loop as I read this, I get a inverse-RIAA like curve instead..when I do a Sweep with RIAA on in settings
View attachment 403398

"bravo"...

 

[AnalogSteph]

2. MA manual say set volumes to 100%, but with 100% on output and input mic under SOUND in windows the noise and distortion is bad, I used a 1000hz signal in MA and found that 20% in Mic/Input and 50% on Output gave optimal noise and distortion when using -1dB setting PLAY GAIN in MA, To get full frequence range to 22khz I needed so set FFT SIZE at 512k

Note, input gain in particular may be mapped quite arbitrarily. Right-click the number field in recording device properties - Levels to select between % and dB, so then you'll have at least some idea what's happening. Anything below 0 dB often (but not always) is purely driver-side digital attenuation that does not actually increase your input level handling and thus should be avoided. Reduce output level instead. For example, on my ALC1200 line-in here, 82 is +6 dB and 55 is 0 dB. I've also had soundcards / interfaces where 100 was the maximum of 0 dB though, which means everything but that particular setting was quite pointless, hence where MA's recommendation is likely to come from.

 

[Balle Clorin]

Cannot see anywhere to select % or dB