• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Review and Measurements of Lynx Hilo ADC (Part 2)

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
13,493
Likes
5,662
Location
Seattle Area
#1
In part 1 evaluation of Lynx Hilo I measured its DAC performance. In this part, I will be showing the performance of its analog to digital (ADC) subsystem. For comparison, I selected my RME AD-2 Pro (not "FS") version.

I won't review the operational aspect as they remain the same. So let's get into measurements and see how they compare.

Measurements
For this test I only measured the performance of balanced inputs (which is all the jacks they have anyway). To simplify the insane matrix of different configurations, I limited my testing to +24 dBU max input level. Both units have programmable input range which allows one to optimize the input for different devices feeding it at varying output voltages.

Let's start with our dashboard view:

Lynx Hilo ADC Dashboard Measurement.png


Here, my APx555 Audio Precision analyzer is the source analog device whose output is being digitized by the respective ADC devices. I set the output of the AP to +24 dBu and to my surprise, I was greeted with lots of distortion. Dialing down that one dB cured that and resulted in the output you see. Instead of -1 dB, we are seeing -0.95 dB. As a result, when I fed it 24 dBu it clips to hair over dBFS. So some trimming is off in the ADC of Lynx Hilo. Best not to push it to the limit.

The RME ADI-2 Pro was tested the same way (i.e. +23 dBu) although it had no trouble with +24 dBu:
RME ADI-2 Pro ADC Dashboard Measurement.png


These are extremely good results with SINAD (usable signal above sum of noise+distortion) at 116 dB to 117 dB or nearly 20 bits. Distortion spikes in our 1 kHz tone are at -130 dB which means absolute inaudibility.

Let's look at (SMPTE) intermodulation distortion versus input analog level:
Lynx Hilo ADC and RME ADI-2 Pro Intermodulation Distortion Measurement.png


Here the Lynx Hilo is 2-3 dB better in noise level but per earlier comment, it clips when you get to near max input value with resulting distortion shooting up.

Let's look at Jitter and Noise:

Lynx Hilo ADC Jitter and Noise measurement.png


Here, the non-FS version of RMA ADI-2 Pro shows its characteristic low frequency random jitter which is supposed to be fixed in the "FS" version which ships standard now. The Lynx Hilo doesn't have that problem and shows essentially perfect results. Yes there are some low frequency spikes but those could be in my generator just as well and at any rate their levels are astonishingly low at < -140 dBFS.

Looking at the spectrum of 1 kHz tone we see:
Lynx Hilo ADC and RME ADI-2 Pro 1 kHz Distortion Measurement.png


When summed in THD+N, the two ADCs add up to the same value. But when the spectrum is broken down per above, we see that the RME ADI-2's harmonic distortion is front-loaded whereas the Lynx Hilo spreads out to some 15 harmonics. I could tell you that from psychoacoustics point of view earlier harmonics are less audible but who are we kidding? The levels are well below threshold of hearing at -130 dBFS so inaudible regardless of make up.

Summary
HIgh-performance professional analog to digital converters show their stuff here. Performance is exceptional and faults are darn impossible to find. If RME had not come up with the FS version, I would maybe faulted its jitter performance. But they have so there is really no juicy story here. Both of these ADCs are high performance converters. They should be fully transparent and nothing to pick between them other than features.

For those of you who just listen to music instead of creating it, take solace in knowing that the distortions created on ADCs are vanishingly small. Get a DAC that matches these and you are golden as far as an end-to-end transparent "channel."

Needless to stay, both the Lynx Hilo and RME ADI-2 Pro ("FS") are recommended.

-------------

As always, questions, comments, recommendations, etc. are welcome.

If you like this review, please consider donating funds for these types of hardware purchases 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).
 

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
3,904
Likes
2,035
#2
Can you check out aliasing and ultrasonic IMD in these? I expect they perform excellently, but worth knowing on an ADC where mics and instruments can hit the ADC with some high level ultrasonics sometimes.

I used a twin tone sweep 2-96 khz from the source while recording at 48 khz. You also could do a single tone sweep for aliasing, but you'll not capture IMD effects. Here is an example. The background of this spectrogram goes to gray at -100 dbFS. You might need to extend it lower with the devices you are testing. In all the ADCs I tested, ultrasonic high level signal raised the general noise floor in the audible band below 20 khz.
twin tone imd sweep aliasing 96.png
 
Last edited:

bennetng

Active Member
Joined
Nov 15, 2017
Messages
212
Likes
58
#4
Can you check out aliasing and ultrasonic IMD in these? I expect they perform excellently, but worth knowing on an ADC where mics and instruments can hit the ADC with some high level ultrasonics sometimes.

I used a twin tone sweep 2-96 khz from the source while recording at 48 khz. You also could do a single tone sweep for aliasing, but you'll not capture IMD effects. Here is an example. The background of this spectrogram goes to gray at -100 dbFS. You might need to extend it lower with the devices you are testing. In all the ADCs I tested, ultrasonic high level signal raised the general noise floor in the audible band below 20 khz. View attachment 13495
RMAA has a twin tone sweep similar to yours. It's called "IMD (swept tones)" in RMAA's html report. The underlying signal looks like this:
IMD (swept tones).PNG


High amplitude and highly concentrated sound like test tones are very uncommon in real music. Raw, unprocessed recordings are usually low in average volume with a few ocassional peaks. Noise floor is more important than distortion figures like 0.00x vs 0.000x% since those distortions will be hidden inside the noise floor in non-test tones anyway. That's also why I didn't pick the Focusrite 18i20 in the post below:
https://www.audiosciencereview.com/forum/index.php?threads/which-dac-would-you-choose.2609/
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
13,493
Likes
5,662
Location
Seattle Area
#9
@amirm did you happen to do an ADC test on the UMC202/204HD?
Nothing formal. I tried to use it an an audio analyzer and gave up. Should do a formal test....
 
Top Bottom