Super Best Audio Friends
The evolution of the original irreverent and irrelevant and non-authoritative site for headphone measurements, i.e. frequency response graphs, CSD waterfall plots, subjective gear reviews. Too objective for subjectivists; too subjective for objectivists
The first rationale for this testing using real headphones was to ascertain the effects of back-EMF with respect to global negative feedback. A resistor load will not provide back-EMF. However a headphone driver really isn't that much different from a microphone. If we shout loud enough into a headphone driver and measure at the phono jack, we will see voltage. The second rationale was to ascertain the effects of back-EMF with respect to current capability. It was cited that USB dongle AIOs exhibited sloppier more one-note bass than desktop headphone amplifiers.
Lo and behold, I most certainly did not expect this! A real headphone load (Sennheiser HD650) resulted in up to 50db worse THD than a dummy 300 ohm load at 37Hz with the Topping L30 amplifier!
Anyway, the One Ring is vanquished. F the Eye of Sauron.
^ Silk baffle vents. I think I roughed up driver front filter paper when I was trying to figure out how to take the rest apart.
Lo and behold, imagine my surprise when Grado released their Hemp with their version of the flat pads, the F-cush. And now it looks like Grado has completely revamped their Prestige series, of which the SR225X and SR325X now come with the F cushions! So course I had to grab what was known as the most aggressive and energetic of the Grados, the SR325, and take it for a test run. This time however with the included F cushions. I will also see how the F cushions perform vs the TTVJ Deluxe Flat Pads on various Grados later on in the thread.
Now before I get into the measurements or subjective impressions (which were quite good), I have to point out something hugely disappointing. The ergonomics and construction are first rate shit and what gives people the impression that China makes garbage. (This is not true). @tommytakis sent these to me in a box (thanks for the Korean treats - we just visited Houston and loaded up a cart at H-mart - however, kids and I pretty much devoured everything in a week) and by the time they arrived, one cup unscrewed itself from the gimble and the wire mesh cover fell off. It took me some effort and tin snips to put the wire mesh properly back on.
Input impedance set to 200kohm. AC coupled. 20khz AES17 bandwidth limit.
4v input 4.2v output (closest I could get to unity gain with inbuilt vol control at 90)
This is a new thread split off from here where @purr1n initially found some discrepancies with the measurements of SINAD chart topping Soncoz SGD1 DAC on Audio Science Review. These discrepancies were significant to the point of downgrading the Soncoz DAC from the one of the "leaders of the pack" to one the laggards behind the leaders. Some people felt the initial discrepancies were because of differences in measurement gear, first a AverLAB, and then an APx525 vs. the state of the art APx555 (ASR).
Further investigation with two additional samples of the SGD1 DAC using the APx555 have confirmed @purrin's initial findings. One positive aspect is that the "IMD hump" fix has been corrected. We do not know if the significantly worse SINAD measurements are the result of this fix or if ASR received a cherry-picked sample from the manufacturer. However, we think it is necessary to let the buying public know that the spectacular SINAD results could not be duplicated with three off-the-shelf production samples, especially to those who rely on measurements to make a determined buying decision. In addition, a third sample showed worse measurements in one channel compared to the other.
ORIGINAL POST STARTS HERE:
So I just put the SGD1 on the APx555 and @purr1n looks like you were right, this is NOT measuring the same as ASR is showing.
-0.5dbfs (to match voltage shown on ASR measurements):
Moondrop Blessing 2 Dusk FR
The Arctis 3 has a severe midrange suckout. It's signature is classic V-shaped, but for some reason I don't hear it as elevated bass and highs because the missing midrange is just so annoying and makes all sounds unnatural. In addition, there is a lot of internal cup reverb, sort of a cheap plastic shell effect.
Let's start with simple frequency response. Note that the sharp narrow dips in the lower treble and high treble are measurement artifacts (to be confirmed in CSDs in later post.) The Flat Plate Coupler was used here to get the most consistent relative results...
The headamps I compared were: Muffsy MC Head Amp (DIY kit), Lounge Audio Copla, Hagerman Audio Labs Piccolo2, Audio Design MCP-1, Musical Fidelity AC-1, Music Reference RM-4. The first three are current production amps (the Muffsy is a kit), the last three are out of production but are still well considered and available (occasionally) on the used market. Why this comparison and these specific headamps?