A recent discussion in the review of Schiit Modi 2 reminded me that I was planning to do a hardware teardown of it. As reminder, the Schiit Modi 2 is a low cost ($120 shipped) USB DAC.
Audio is captured through the USB port and output on those pair of RCA jacks. The only thing unusual is that "E/S" switch that puts the DAC either in 24/96 mode or supports higher resolution to 192 KHz (different USB classes). It is an ill-intended feature especially since Windows 10 Creator Edition no longer requires drivers for either mode.
The unit is simply designed but uses a very hefty gauge of formed sheet metal which gives the unit nice weight to sit on the desk unlike many budget dacs, Screws are threaded which is nice and easily open and expose what is inside. The silver color is utilitarian and is not going to...
This is a concurrent review of two DACs, the famous "O2 DAC" by Nwavguy from our neck of the woods and the E10K Olympus 2 from Fiio. They both use the TI PCM5102 DAC chip so makes for an interesting comparison.
While the ODAC is quite sparse package with just a USB connector and 3.5mm output, the Fiio E10 has a headphone amplifier with both bass boost and gain settings, plus a S/PDIF coax output. They are both quite small and fit in your hand so are great portable solutions to take on the road if needed.
We are privileged to have James Johnston ("JJ") as one of our members. As one of the luminaries in audio research, it has been a pleasure to read his past presentations to the local chapter of Audio Engineering Society. JJ has kindly given me permission to post links to his work per below. I suggest downloading them and reading them before bed.
This is a highly detailed review and measurements of the "audiophile" digital audio player, Alien+ by a company called Shozy out of Singapore. These players use "desktop" class DAC silicon and such, aiming to produce the same sound you would get from your home system. They also have much higher power headphone output than say, a cell phone.
The Shozy Alien+ is an all metal portable player. That makes it quite hefty but also pain in the hands to use because of super sharp corners. As is, I don't think I could use this device without some kind of skin/case.
Here is what they say about it and a picture of the unit:
Much to my surprise, the unit would not power on without putting a micro-SD card in there! Nor could I find a manual for it anywhere online. The unit was loaned to me and fortunately the person who had bought it told me about having to put the microSD card in there.
Even worse is that while the Alien+ is powered using a...
The device is obviously made out of plastic but it is not as cheesy as that sounds. The metal red color makes it look like it is made out of metal. The UCB cord as you see is permanently attached so no tweaking with $1000 UCB cables is possible!
Functionality is pretty good given the headphone output, optical S/PDIF and aforementioned analog to digital converter. Unfortunately sampling rate is limited to 48 Khz.
For this testing I did my comparison against two other low cost DACs: the Topping D30 ($129) and...
Let me confess that I have had a man-crush on the look of the teac NT-503 for quite a while! Compared to a lot of utilitarian DACs that I test, the Teac looked so much nicer and professional in the pictures. Alas, at $1,000 retail price, I was reluctant to purchase it. Fortunately due to kindness of a friend of a member here, I received a unit for evaluation.
In person the rack handles are a bit much and get in the way a bit so could do without them. There is a handsome white LED/OLED that is informative and pretty. Menu navigation is through the handle in the middle and easy to figure out. Outputs are controlled through that which means it shuts off one or the other (RCA or...
I will do a hardware tear down later but for now, the enclosure seems nice quality and a step above typical DIY shops. The unit is externally powered and surprisingly with a Topping branded switchmode power supply. Typically people buy these in open market instead of having one made for them with custom label. It has higher than normal output of 15 volt which helps it with higher output drive as you see later.
Capabilities are excellent with PCM up to 192 Khz and DSD up to DSD128. Furthermore, the unit comes with not only USB input but also coax and optical S/PDIF inputs. Nice!
As always I started with J-Test to measure noise floor and jitter. For reference, I also test the Behringer UMC204HD, our king of low...
Question was asked about its headphone performance. So I setup a quick test, driving both my Audio Precision analyzer with 300 ohms (not ideal but good enough) and a pair of Sony MDRV6 headphones for subjective testing. As a comparison, I also put next to it the Exasound E32 which retails for $3,500.
Subjective results/listening test
I played one of my audiophile tracks and listened using my Z-series HP laptop in-built headphone out. Sound was good although at max volume, not deafening. I then switched to the Behringer. I had to turn up the volume on it to mid-position to get it to be louder than my laptop output. There, it provided a slight improvement in fidelity.
I then turned up the volume further and the fidelity went to hell...
I have been reviewing a lot of low cost DACs recently. I wanted to have a high-performance DAC as a reference. My best DAC is in my audio system and pain in the neck to relocate back and forth. So I set out to find a DAC in $2000 range (my cost). Idea was to have a very low noise/low distortion DAC that would be revealing of any tweaks put in front of them.
After getting suggestions from the forum, I short-listed it to Benchmark and Exasound. Both of them provide measurements on their site which gave me confidence of good design. As it turns out, I reached out to Exasound and they immediately answered so I went with them. I asked for accommodation pricing on E32 DAC and I received a good discount. As a professional courtesy I don't want to say how much that is. Suffice it to say it is similar to dealer margin for high-end products. Should this have been a transaction with someone I know, the discount is usually 10 to 20% higher. Still, I thought it was a reasonable...
The third-day was a rather short one for me since the show closes early. But also because I attended an amazing presentation by Avalon as you will see later. It capped a very nice show and a relaxing one. I hope the show was successful for the organizers and it continues.
Hello you all. So the day 1 at the Rocky Mountain Audio Fest (RMAF) came to a close. It was a calm and "orderly" day with little to gripe about . Being part of the press, I did not have to wait in this line where last year they could not find my badge.
The line had died a few hours later.
The rooms had light to medium attendees. But when I asked a few companies what traffic they were seeing, they all said it was quite high and they were very satisfied with it seeing how it is not the weekend.
The weather outside is perfect with leaves starting to turn and super comfortable temps. But what the heck is going on here???
Monday is the day I fly out! How do we go from 70s to 30s with snow and then back to near 70s???? It does not compute!
Had great number of conversations with industry folks. Unfortunately i can't share much of it with you all.
The Henry Engineering Matchbox II was loaned to me by a member for measurements and hardware teardown/review. I am not sure how well known this DAC is. It is targeted toward television broadcast world. It unusually has both ADC and DAC plus professional AES/EBU output (balanced version of S/PDIF). In that regard, it appropriately only has balanced inputs and outputs.
Retail price is fairly high for consumer market but appropriate for professional use at $479.
Specs are rather modest, stopping at just 48 Khz sampling and bit depth of 16 bits. Again, this is fine for video applications where 48 Khz sampling is standard and 16 bits sufficient.
As always, my go-to measurement is 24-bit, 48 Khz J-test signal. I had not noticed that this device is limited to 16 bits when I did the testing so the 24-bit depth of the signal is lost on it. Indeed, that shows up in the measurements:
I was recently asked about merits of S/PDIF versus USB for audio DACs. It has been said that S/PDIF was designed for audio whereas USB is a computer interface. And that makes USB noisier and less desirable interface.
I think most of you know my opinion on this. But just in case, I believe USB to be a superior and more "correct" interface for audio. Problem with S/PDIF is that it makes the source the "master," forcing the DAC to chase its timing. This means that if the source S/PDIF signal is not very clean, it can impact target DAC performance. Fortunately over the years S/PDIF interface has been perfected a lot and even in low cost implementation it can be excellent.
Still, there is no reason to have this antiquated architecture. Using asynchronous mode USB, the DAC can set the cadence using a high-performance clock and force the source, in this case a computer or streamer, to follow it.
Yes, there is some risk of noise here as USB is a much more complicated interface...
This is a review of the Musical Fidelity V-DAC II including measurements. Member Ron Party was kind enough to l0an this to me. This is an older DAC, dating back to 2012 or so and retailed for $379. It comes with an external power supply which looks to be a linear one.
As usual, my first measurement is J-Test signal at 48 Khz sampling and 24 bits. Here is the outcome as compared to iFi iDSD which is a much newer DAC at similar price point:
As we see there, the noise floor of Musical Fidelity V-DAC II is lower than iFi iDSD even though its output is higher (i.e. has a better signal to noise ratio). Just eyeballing it, it seems to have 5 to 6 db advantage over iFi.
Given the linear power supply, its output is free of mains related harmonics. So overall, a very nice showing here.
I have also shown the performance of V-DAC using both its USB input and S/PDIF. S/PDIF was generated from my USB port using an Audiophilleo USB to S/PDIF converters. As...
The previous thread on DAC fundamentals provided an overview of conventional (Nyquist) DACs. This thread will introduce oversampling and the delta-sigma architecture that dominates the DACs used in consumer audio gear today.
A few definitions:
Nyquist = fs/2 = 1/2 the sampling frequency. This is the highest frequency that a sampled system can correctly capture and reproduce. Any higher, and the frequency information is lost. Note that Nyquist applies to the highest frequency in the signal, so an audio system can reproduce a 20 kHz sine wave ( a single tone) but not a 20 kHz square wave (which has many higher harmonics). A system sampling at frequency fs, e.g. 40,000 cycles per second (40 kHz), can acquire up to (but not including) 20 kHz signals.
Oversampling refers to how much "extra" bandwidth, or sampling rate, we have relative to the Nyquist rate. For the...
The purpose of this thread is to provide a quick introduction to digital-to-analog converters (DACs), the magical things that turn digital bits into analog sound. Previous threads have discussed sampling theory, aliasing, and jitter. Now we’ll get down to the hardware and take a look at some basic DAC architectures.
The two criteria most often used to describe a DAC are its resolution (number of bits) and sampling rate (in samples per second, S/s, or perhaps thousands of them, kS/s). If we think about producing an analog output both of these are important. The resolution determines the dynamic range (in dB) of our DAC, and sampling speed determines how high a signal can be output. As discussed in those earlier threads, resolution sets an upper limit on signal-to-noise ratio (SNR) and spurious-free dynamic range (SFDR, the difference between the signal and highest spur). For an ideal (perfect) DAC, we can find: