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Measurement and Review of JDS Labs USB OL DAC

amirm

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#1
This is a measurement and comparison of JDS Labs USB OL DAC against the NWAVGUY's Objective DAC (also sold by JDS Labs). I also compared it to my reference budget DAC, the Topping D30. See my measurements of Objective Rev b DAC here: https://audiosciencereview.com/foru...dslabs-odac-rev-b-compared-to-fiio-e10k.2068/

And topping D30: https://audiosciencereview.com/forum/index.php?threads/topping-d30-dac-measurement-and-review.2016/

The JDS Labs OL DAC comes with USB-input variant at $99 which is what I purchased. And another with Toslink optical input pushing the price a whopping $40 more to $139. The Objective DAC sells for $129 which is the same price as Topping D30. But topping is a lot more feature rich with Toslink and S/PDIF inputs.

JDS Labs OLDAC.jpg

As you see in the above picture, the OL DAC improves on the Objective DAC with the addition of linear external DC input at 15 volts.

Physically the box is the typical DIY type box with a bid of texture added for good measure. There are no feat on it so it is easily dragged by its cables. It came with a monoprice labeled USB cable which I did not use.

The cardboard box that it came in gets the award for the cheapest and lousiest looking packaging you can imagine. It would make an Apple designer go on hunger strike after just one look. Yes, you don't use the box but even budget $30 chinese DACs come with better packaging than this.

I tested the unit using Roon as usually playing the signal files and my Audio Precision Analyzer handing the measurements. As always you see comparisons here but I got lazy this time and used my previously recorded measurements for Topping D30 and Objective2 DAC. Usually I remeasure but I think the results would be the same.

I used Windows 10 inbox USB class audio driver so everything was thankfully plug-and-play. Reported formats supported are the typical under 96 Khz job:

upload_2018-1-14_20-10-5.png


Thankfully there are no holes in there up to that limit.

Measurements
As always we start with our test of jitter and noise using 24-bit, 48 Khz signal (should show up as a single tone at 12 Khz). First up is comparison you have been waiting for: against the Objective Rev B DAC:

J-Test JDS ODAC jitter compared to Objective ODAC.png


It is an across the board win for the OL DAC. Lower noise floor and almost complete absence of jitter and odd spurious tone in the Objective2 DAC.

The Topping D30 though, does still better:

J-Test JDS ODAC jitter compared to Topping D30.png


The Topping squeezes the noise floor just a bit more while outputting a bit higher level signal. So overall it is slightly superior there.

Let's move to 1 Khz harmonic distortion test against the Objective DAC first:

1 Khz harmonic distortion JDS Labs ODAC vs Objective DAC.png


Once again we see the clear advantage in noise floor of the OL DAC over Objective DAC.

On the harmonic structure, they are opposite beasts with the OL DAC generating odd harmonics and Objective, even. This translates into potentially more objectionable audible issue for OL DAC as harmonics go up. But the levels are so low that I can't make a practical case for it. Overall, I give a small victory to OL DAC here.

I forgot to save the comparison against Topping D30. :( Looking at the past measurement, the Topping D30 has the same harmonic structure as the Objective DAC and at lower levels. So the Topping D30 wins this round again.

Lastly I tested the "linearity" of OL DAC while trying to reproduce a very low level sine wave, comparing it to Objective DAC:

Linearity Measurement JDS Labs OLDAC vs Objective DAC.png


The lower noise of JDS OL DAC makes a small improvement her as we go from negative to positive swings but the difference is very small. Both are pretty respectable for this price range. Topping D30 is also within the same ballpark.

Summary:
From engineering point of view, JDS Labs and their design shop (same one as Objective DAC) have done a nice job of improving this DAC. At $99 with the same feature set, I really see no reason to purchase the NWAVGUY's Objective Rev B DAC. This is cheaper and better.

Compared to the Topping D30, it loses out on measurements and features. Addition of Toslink makes it even more expensive than Topping D30 yet still lacks S/PDIF. Topping also supports 192 Khz and DSD format which the OL DAC does not.

So my top recommendation for a budget DAC remains the Topping D30. But kudos to JDS Labs for improving on the original design while reducing the price some.

If you like this review, please consider donating funds for these types of hardware purchase using Patreon (https://www.patreon.com/audiosciencereview), or upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
 
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#2
Good review.

However, you shouldn't call it "JDS ODAC" in the graphs. The OL DAC is not an ODAC.
 

drconopoima

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#3
The odd harmonics are below audible range*. After all, I guess the well-engineered Chinese DACs will have the upper hand vs American companies considering they have lower production costs.

*Based on several blog posts by nwavguy in which he called the 65db audio tape hiss as "some might argue this level of distortion could be audible under some conditions" (or he could also have been talking about the Nuforce uDac -45db levels of distortion), and anything below 80db as "considered by experts to be potentially audible".
 

mindbomb

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#4
Although the performance overall does look pretty good for $99, I have to note that jdslabs claims a thd+n of .001% 20hz-20khz. Maybe it is true at -3db or something, but it seems misleading when we have results where the third harmonic itself is greater than that.
 

jseaber

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#5
Hey, thanks for sharing. To clarify, I've conducted all DAC measurements at -0.15dBFS for years, which includes all THD+N measurements. IIRC, this choice was discussed in the 2015 ODAC RevB release article. Full scale (0dBFS) output of most DACs increases THD.
You can compare with our own measurements here, where you can find my plot of the 20-20kHz THD+N sweep @ -0.15dBFS:
http://blog.jdslabs.com/2017/04/odac-vs-ol-dac/

Not too long ago, someone suggested applying digital attenuation at the input of the DAC. This is commonly programmed behavior in pro audio DACs to expand mixing headoroom. I'm still considering whether the audiophile market would be receptive. Technically, some frontend digital attenuation would improve 0dBFS measurements, but it violates the idea of bitperfect listening, which is important to some. And the occurrence of 0dBFS peaks varies with music collection. We can all agree that good recordings should avoid 0dBFS peaks.

tl;dr - No intention to deceive. All measurements, including those of ODAC, are shared and conducted at -0.15dBFS.

Feel free to ask any questions.

--JDS
 

bennetng

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#6
Hey, thanks for sharing. To clarify, I've conducted all DAC measurements at -0.15dBFS for years, which includes all THD+N measurements. IIRC, this choice was discussed in the 2015 ODAC RevB release article. Full scale (0dBFS) output of most DACs increases THD.
You can compare with our own measurements here, where you can find my plot of the 20-20kHz THD+N sweep @ -0.15dBFS:
http://blog.jdslabs.com/2017/04/odac-vs-ol-dac/

Not too long ago, someone suggested applying digital attenuation at the input of the DAC. This is commonly programmed behavior in pro audio DACs to expand mixing headoroom. I'm still considering whether the audiophile market would be receptive. Technically, some frontend digital attenuation would improve 0dBFS measurements, but it violates the idea of bitperfect listening, which is important to some. And the occurrence of 0dBFS peaks varies with music collection. We can all agree that good recordings should avoid 0dBFS peaks.

tl;dr - No intention to deceive. All measurements, including those of ODAC, are shared and conducted at -0.15dBFS.

Feel free to ask any questions.

--JDS
https://www.audiosciencereview.com/...ation-audible-intersample-clipping-test.2231/

That's why I said I don't like the idea of blaming those who make music or DACs for intersample clipping. Who needs "bit perfectness" if it means clipping? IMO end users should aware of the fact that DACs need oversampling and filtering.

By the way, can you measure the non-clipping volume of the ODAC by using my test signal mentioned in the post above? Thanks.
 

amirm

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#7
However, you shouldn't call it "JDS ODAC" in the graphs. The OL DAC is not an ODAC.
Thanks. I had gotten it right in some of them but missed the first two instances. I just corrected them. It is a hell of a mess with these names and these DACs!
 

amirm

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#8
Hey, thanks for sharing. To clarify, I've conducted all DAC measurements at -0.15dBFS for years, which includes all THD+N measurements. IIRC, this choice was discussed in the 2015 ODAC RevB release article. Full scale (0dBFS) output of most DACs increases THD.
You can compare with our own measurements here, where you can find my plot of the 20-20kHz THD+N sweep @ -0.15dBFS:
http://blog.jdslabs.com/2017/04/odac-vs-ol-dac/
Warm welcome to the forum! And big thanks for posting measurements of your products. The number of DAC companies at these price points posting such is next to zero. I only know of Topping and your company.

On using less than zero db I see the case for that. I continue to use it because we have found clipping errors in some DACs at 0 db.

Lack of standardization of measurements is a problem in this space. It is very difficult at times to compare any two measurements. As a group we are working here to try to get better consensus on it.
 

amirm

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#9
Although the performance overall does look pretty good for $99, I have to note that jdslabs claims a thd+n of .001% 20hz-20khz. Maybe it is true at -3db or something, but it seems misleading when we have results where the third harmonic itself is greater than that.
Commenting further, we are a long ways away from have measurements that can be compared with other published ones. Different measurement gear and especially measurement parameters make these comparisons hard even for me. Over time I like to close the gap as seen by my test of non-linearity with -90 db signal that stereophile is using.

So for now, just use my measurements relative to what else I have measured. Verifying manufacturer's specifications and measurements is a different assignment. :) If requested though, I can try to dig into differences. When I get time let me repeat it with -0.15 dbFS input and report back.
 
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#12
The D30 really is a great budget DAC :)

It's a shame its matching amplifier (A30) has a high output-impedance (1o Ohms on the 1/4" output and 30 Ohms on the 1/8" output). I would imagine most people will use planar or high-impedance dynamic headphones with the A30, so it's likely not a problem for most folks, but still a minor annoyance.

Thanks for the measurements.
 

amirm

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#14
Welcome to the forum Luke. I did order the A30 to test but the seller backed out saying they no longer carry it (through Amazon). Didn't realize it had high output impedance.

I will be testing the Topping combo DAC+amp the DX-7 next so maybe that fits the bill. :)
 

Jimster480

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#15
Welcome to the forum Luke. I did order the A30 to test but the seller backed out saying they no longer carry it (through Amazon). Didn't realize it had high output impedance.

I will be testing the Topping combo DAC+amp the DX-7 next so maybe that fits the bill. :)
I have 2x A30's so I can loan you one for testing if you like. I have swapped the OpAmp chip in one of them too. Would be interesting to see how that measures!

The A30 sounds nice but its higher output impedance affects clarity on lower impedance headphones even if they are planar. You cannot avoid the differences in voltages moving the frequency response around.
 
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#16
I have 2x A30's so I can loan you one for testing if you like. I have swapped the OpAmp chip in one of them too. Would be interesting to see how that measures!

The A30 sounds nice but its higher output impedance affects clarity on lower impedance headphones even if they are planar. You cannot avoid the differences in voltages moving the frequency response around.
Just a friendly suggestion. Might be a good idea to swap the original opamp back in if you still have it. Assuming this is the gain stage opamp, at best you may have slightly improved a few db's of noise. Worst case, the circuit may be unstable.
 

amirm

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#17
I have 2x A30's so I can loan you one for testing if you like. I have swapped the OpAmp chip in one of them too. Would be interesting to see how that measures!

The A30 sounds nice but its higher output impedance affects clarity on lower impedance headphones even if they are planar. You cannot avoid the differences in voltages moving the frequency response around.
Thanks. I have an a30 on order but we could measure your mod to see what it has done.
 

Jimster480

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#18
Just a friendly suggestion. Might be a good idea to swap the original opamp back in if you still have it. Assuming this is the gain stage opamp, at best you may have slightly improved a few db's of noise. Worst case, the circuit may be unstable.
I bought a whole bunch of OpAmps just to test them out.
It has OPA2134 originally, I bought OPA2227, NE5532, LM4562, NJM4562.
OPA2227 was more grainy, NE5532 I couldn't really hear any difference with, maybe slightly compressed / grainy in some signal sweeps (but you really have to test it back to back to notice it) and then LM4562 sounded slightly better overall. So I left the LM4562 in there.
The slew rate is not much higher so the circuit should not be unstable, I factored for power differences of the different OpAmps.
 
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