Suggestions for the easiest/most convenient way to level match between DACs?

Hi everyone, I am interested in comparing my 4 DACs in my main system as follows:

PC -> intona USB isolator -> 4 port passive USB hub, each USB port connected to 1 dac to my Schiit freya + preamp input -> all converted to balanced output to my power amp to speakers/subs

But before i can do that I need to volume match the 4 DACs, I am thinking of using REW to measure using the built-in SPL meter with a mic at listening position and for each dac to play a tone and record the volume level differences say DAC A shows 75db and DAC B shows 78.5db then in my actual comparison I will simply add back +3.5db to DAC A.

I also have one of those iphone app that uses the iphone as a SPL meter, but not sure how accurate that is...

Any suggestions on whether there is any other way that might be easier for me to do this? 

Cheers

Deric

1 minute ago, dericchan1 said:

Hi everyone, I am interested in comparing my 4 DACs in my main system as follows:

 

PC -> intona USB isolator -> 4 port passive USB hub, each USB port connected to 1 dac to my Schiit freya + preamp input -> all converted to balanced output to my power amp to speakers/subs

 

But before i can do that I need to volume match the 4 DACs, I am thinking of using REW to measure using the built-in SPL meter with a mic at listening position and for each dac to play a tone and record the volume level differences say DAC A shows 75db and DAC B shows 78.5db then in my actual comparison I will simply add back +3.5db to DAC A.

 

Any suggestions on whether there is any other way that might be easier for me to do this? 

 

Cheers

 

Deric

 

I've done this before, but with a preamp that had a digital volume display, adjustable by .1 dB. The Freya will make it harder to be precise. 

You could even try using an app on your phone to measure SPL while playing a 1 kHz tone. 

How do you plan to add +3.5 dB to DAC A if needed?

1 minute ago, The Computer Audiophile said:

 

I've done this before, but with a preamp that had a digital volume display, adjustable by .1 dB. The Freya will make it harder to be precise. 

 

You could even try using an app on your phone to measure SPL while playing a 1 kHz tone. 

 

How do you plan to add +3.5 dB to DAC A if needed?

Thanks Chris, I actually plan to make the Freya fixed volume say "make DAC A at 75db with the Freya" as a reference point, then DAC B could be measured at +3.5 db, DAC C could be measured at -2.2 db, DAC D could be measured at -1.6db......

Once I have these levels, I will leave the Freya volume fixed, but use Hqplayer as a playback device - DAC A will be NAA A, DAC B = NAA B...... so I can choose which NAA to play, so if NAA A starts in Hqplayer at -6db, I will set NAA B at -2.5db to account for that +3.5db difference. Does that make sense?

Just now, dericchan1 said:

Thanks Chris, I actually plan to make the Freya fixed volume say "make DAC A at 75db with the Freya" as a reference point, then DAC B could be measured at +3.5 db, DAC C could be measured at -2.2 db, DAC D could be measured at -1.6db......

 

Once I have these levels, I will leave the Freya volume fixed, but use Hqplayer as a playback device - DAC A will be NAA A, DAC B = NAA B...... so I can choose which NAA to play, so if NAA A starts in Hqplayer at -6db, I will set NAA B at -2.5db to account for that +3.5db difference. Does that make sense?

Excellent. That sounds very cool. 

1 minute ago, The Computer Audiophile said:

Excellent. That sounds very cool. 

Thanks Chris, I also have an iOS SPLnFFT app but not sure how accurate is that compared to using a u-mik with REW. I will report back once I have a chance to set everything up.

Cheers

Deric

1 hour ago, dericchan1 said:

Hi everyone, I am interested in comparing my 4 DACs in my main system as follows:

 

PC -> intona USB isolator -> 4 port passive USB hub, each USB port connected to 1 dac to my Schiit freya + preamp input -> all converted to balanced output to my power amp to speakers/subs

 

But before i can do that I need to volume match the 4 DACs, I am thinking of using REW to measure using the built-in SPL meter with a mic at listening position and for each dac to play a tone and record the volume level differences say DAC A shows 75db and DAC B shows 78.5db then in my actual comparison I will simply add back +3.5db to DAC A.

 

I also have one of those iphone app that uses the iphone as a SPL meter, but not sure how accurate that is...

 

Any suggestions on whether there is any other way that might be easier for me to do this? 

 

Cheers

 

Deric

If you have a decent voltmeter, use that to measure the level at the output of a DAC at 1kHz and adjust the volume(s) accordingly. Microphone measurements of SPL levels are not very reliable or accurate due to background noises, room interactions, positioning, etc. 

9 minutes ago, pkane2001 said:

 

If you have a decent voltmeter, use that to measure the level at the output of a DAC at 1kHz and adjust the volume(s) accordingly. Microphone measurements of SPL levels are not very reliable or accurate due to background noises, room interactions, positioning, etc. 

Thanks. I got one of these from amazon not sure how accurate it is tho. 😀

https://www.amazon.ca/gp/product/B08ZC2C8WC/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

9 minutes ago, pkane2001 said:

background noises, room interactions, positioning

Even though those remain the same for each DAC, is still critical?

4 hours ago, dericchan1 said:

Thanks. I got one of these from amazon not sure how accurate it is tho. 😀

 

https://www.amazon.ca/gp/product/B08ZC2C8WC/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

These multimeter AC RMS voltage function is designed to measure 50Hz or 60Hz sine signal and tend to indicate way lower voltage values in 1kHz sine. Though it is easy to test it by yourself, measure output voltage of several different frequencies with WaveGene or other sinusoidal signal generator app, and use 60Hz sine signal when indicated value of higher frequency such as 1kHz seems not reliable

This is what I used. Connected three different DACs to three different inputs of a preamp. I played a 1khz tone and got as close as I could to a 1/10 dB difference between them. 
 

https://www.sweetwater.com/store/detail/CM140--galaxy-audio-check-mate-cm-140-spl-meter