Yet another A/B test of DACs

[julian_hughes]

When I did it, it was to compare various DAPs & phones so it was easy to use line out to PC's line in & adjust the level on each device. With DACs I guess you need to either adjust their digital output in alsamixer or similar, or run them through an amp or preamp and note the exact settings for each to be level matched. I think you could get very accurate matching. I think my limitation was that some phones and DAPs had rather coarse level adjustment.

 

[raif71]

^^^Yes, it can serve as an example to other people, how to do it, how to start.
...So you could provide information about the comparator, like where to get it and how much. ...It needs to be inexpensive.

I bought this locally using Malaysia's online store but I see in amazon they have the same switch here.

 

[Count Arthur]

With a test tone, would a sound meter app on a phone be good enough?

 

[Blumlein 88]

With a test tone, would a sound meter app on a phone be good enough?

Usually not. If you can get one that will average over a few seconds it would work.

 

[Blumlein 88]

When I did it, it was to compare various DAPs & phones so it was easy to use line out to PC's line in & adjust the level on each device. With DACs I guess you need to either adjust their digital output in alsamixer or similar, or run them through an amp or preamp and note the exact settings for each to be level matched. I think you could get very accurate matching. I think my limitation was that some phones and DAPs had rather coarse level adjustment.

Yes this would work.

 

[Blumlein 88]

Get a cable like this one. Male on both ends. Plug it in place of your headphones. Many people have one to connect telephone to car stereos.
You can use the other end to check voltage output with a multimeter. It can be a bit fiddly, but not terribly so. Put the black lead on the sleeve or ground portion. Put the red lead on one of the other parts of the plug to check either right or left channel. If you have balanced headphone outs, then this will be different.

Find a comfortable volume for your test with one of your DACs. Without changing volume send it a test tone, 1 khz is fine, 440 hz might be better for a cheap multimeter. I'd suggest a -6 db tone. Write down the voltage. Switch to your other DAC, and sending it the same test tone, adjust volume on it to match the voltage reading with your first DAC. Get the two within 1% of each other. If you read 1.oo volts then you want something between .99 and 1.01 volts. Takes longer to read these instructions than to do it once you have done it a couple times.

Now as long as you don't change volume on either DAC you can switch back and forth with matched volumes. If you have a headphone amp you can even change volume on it as long as the DACs are putting out the same voltage/volume.

 

[raif71]

Get a cable like this one. Male on both ends. Plug it in place of your headphones. Many people have one to connect telephone to car stereos.
You can use the other end to check voltage output with a multimeter. It can be a bit fiddly, but not terribly so. Put the black lead on the sleeve or ground portion. Put the red lead on one of the other parts of the plug to check either right or left channel. If you have balanced headphone outs, then this will be different.

Find a comfortable volume for your test with one of your DACs. Without changing volume send it a test tone, 1 khz is fine, 440 hz might be better for a cheap multimeter. I'd suggest a -6 db tone. Write down the voltage. Switch to your other DAC, and sending it the same test tone, adjust volume on it to match the voltage reading with your first DAC. Get the two within 1% of each other. If you read 1.oo volts then you want something between .99 and 1.01 volts. Takes longer to read these instructions than to do it once you have done it a couple times.

Now as long as you don't change volume on either DAC you can switch back and forth with matched volumes. If you have a headphone amp you can even change volume on it as long as the DACs are putting out the same voltage/volume.

View attachment 108402

I will try this method. From what I gathered, the D10s doesn't have volume control but the smsl m400 does. So hopefully the voltage range of the m400 is more than the d10s so that I can dial down its value to match the volume of the d10s. Does that make sense?

 

[Chrispy]

Yawn.

 

[julian_hughes]

I will try this method. From what I gathered, the D10s doesn't have volume control but the smsl m400 does. So hopefully the voltage range of the m400 is more than the d10s so that I can dial down its value to match the volume of the d10s. Does that make sense?

I have a D10 (not D10s) & you can definitely adjust its output level. For example here is a screenshot of alsamixer showing the level control. I assume the same control can be found in Windows or Mac audio.

 

[raif71]

I have a D10 (not D10s) & you can definitely adjust its output level. For example here is a screenshot of alsamixer showing the level control. I assume the same control can be found in Windows or Mac audio.View attachment 108436

I will be using hiby r5 and the usb volume out will be set to fixed volume

 

[raif71]

ya get a MM

Seen anything appropriate at Shopee?

 

[JustAnandaDourEyedDude]

After matching voltages while checking with a multimeter say, would it be worthwhile to switch which DAC connects to which jack and re-check that the two voltages still match? Would any contact resistance inequality at the switch or jack contacts show up in such voltage measurements, which presumably draw very little current? Or would one need to measure resistances or current draws instead? Or would any imperfections in the switch likely be so small that none of the above would be a concern, given other uncertainties such as making good contact with the MM's probes? I guess it should be easy enough to use a MM and two aux extension cords to check that the resistance of each path in the switch is negligibly small?

 

[Blumlein 88]

I will try this method. From what I gathered, the D10s doesn't have volume control but the smsl m400 does. So hopefully the voltage range of the m400 is more than the d10s so that I can dial down its value to match the volume of the d10s. Does that make sense?

yes it does. Check volume with the weaker device and lower the other to match it.

 

[Blumlein 88]

I have a D10 (not D10s) & you can definitely adjust its output level. For example here is a screenshot of alsamixer showing the level control. I assume the same control can be found in Windows or Mac audio.View attachment 108436

I don't think Windows will let you do that with two devices. Maybe I'm thinking about it wrong. Mac probably does. If you can do it with the hardware controls in this case it is likely the better way.

 

[restorer-john]

Great AB comparator you have there.

That's not a comparator. This is a comparator! (apologies to Croc Dundee)

 

[Blumlein 88]

After matching voltages while checking with a multimeter say, would it be worthwhile to switch which DAC connects to which jack and re-check that the two voltages still match? Would any contact resistance inequality at the switch or jack contacts show up in such voltage measurements, which presumably draw very little current? Or would one need to measure resistances or current draws instead? Or would any imperfections in the switch likely be so small that none of the above would be a concern, given other uncertainties such as making good contact with the MM's probes? I guess it should be easy enough to use a MM and two aux extension cords to check that the resistance of each path in the switch is negligibly small?

You could check both if you want. If I understand rightly, he intends to feed each of the two DACs into an amp. So the headphone amp will buffer the DACs. In such a case there likely isn't a big difference. And as long as he matches at the output of the headphone amp any minor differences will have already been adjusted for.

 

[restorer-john]

The easiest and most accurate way to level match without test gear is the null method. You also can accurately null at medium to high frequencies which you cannot do with a cheap DMM.

Feed the left output only from each D/A into the left and right channels of a normal (not BTL) stereo amplifier. Connect to the L/R hot (+) speaker terminals only with a single speaker.

Play the same source at the same time on each D/A and trim the output level on one to produce a null (no sound).

This will work as long as your amplifier is decent (matched channel gain), there are not huge differences in latency between the two D/As and they both preserve absolute polarity.

 

[Thalis]

Seen anything appropriate at Shopee?

Budget? The digital ones range from like 15 to 100 bucks.

 

[raif71]

Budget? The digital ones range from like 15 to 100 bucks.

Get me something in the middle. Thanks

 

[Thalis]

Get me something in the middle. Thanks

maybe this one...

https://shopee.com.my/PRO'SKIT-MT-1...LECTRONIC-HOBBYIST-TOOL-i.56658521.3520275595

Just over 100 bucks can get quite canggih ones