Hi everyone, I have lurked accountless for a while but want to give back a little. I've been making some flat-plate coupler (FPC) measurements with a small selection of different pads which I wanted to share with you all. I'm using the SR80i for the experiments, with a Sennheiser HD6XX as reference. The usual disclaimers about FPC apply: I find the plot of my HD6XX to match what I hear up until about 5-6kHz, and from then on the amplitude is broadly correct but any peaks, dips, or nulls I hear aren't reflected at all.
Here is the SR80i with stock S cushion against HD6XX as baseline:
Second,
'velvet' pads from aliexpress:
Large excess between 2-3kHz is completely eliminated, but there are now enormous peaks in the treble, an odd little one between 1-2kHz, and increased much increased bass.
Adding a ring of 3ply tissue before the driver (the sort you blow your nose with):
This calms the 10kHz+ region to more palatable levels but the 5-7kHz region is still horrible to listen to. Attempts to EQ it out with a -10dB peaking filter of Q=2 at 6kHz lends a muffled quality to the treble. I will put this down to my FPC not reflecting the true interactions with the ear at those frequencies, thereby making EQ very difficult. My hypothesis is the treble is not quite as bad as it looks on a FPC by the time it passes the concha and ear canal, but there is obviously something amiss there nonetheless.
Thirdly the 'velvet protein skin' version from the above aliexpress seller:
I listened to these before measuring (for about 3 seconds). They sound as bad as the graph looks. Proof Grados
can do sub-bass perhaps? No point even trying to modify these.
Next,
third party G cushions also from aliexpress:
Nothing surprising here, although not official G cushions this reflects what others have shown, such as Tyll in his SR225i pad experiments from back in the day: 2-3kHz excess is somewhat reduced or at least narrowed, but in exchange for much increased treble above 4kHz.
Adding some 3ply tissue as before:
This is a bit more like what I want to see. At this point they sound more neutral and you'd be forgiven for not noticing how excessive the treble still is if you didn't first refer to something like the HD6XX, though it is pretty obvious with tracks you are familiar with.
I wanted to try these pads partly to see if some change in 'soundstage' could be induced; especially those velvet pads which bring the drivers 45mm from your ear. Trying out some studio recorded rock, metal, even jazz produced no discernible change to me, however. With the velvet pads there was some sense that the sound was originating from further sideways but if anything this made the sense of space worse because it created the artificial sense that the music was panned even harder left and right than it really was.
With the G cushions things were generally more positive. They are quite deep, about 35mm, but because they are so wide and flat the drivers sit much closer to your ears. The way the treble is quite uniformly increased compared to the velvet pads is much less unpleasant. At first it appears like detail and I enjoyed the unique sound but it becomes fatiguing extremely quickly, even with tissue to dampen. Again, soundstage differences weren't perceived besides a few very specific scenarios: solo piano e.g. Chopin recordings, some Django Reinhardt tracks, and hard-panned studio recordings such as early Beatles. The Django Reinhardt in particular I really dislike listening to on headphones but the Grados with G cushions brightened it up and brought it out my head to a point where it was not so bad. Similar effect with piano and hard-panned recordings but to a lesser extent, although I still can't listen to things like Beatles without a little cross-feed which I was still using here.
Bringing down the treble with EQ, as I mentioned before, pretty much ruined the effect, however. This makes me think this added sparkle and airiness you get is really what brings the sound out the center of your head with the G cushions.
Overall I enjoyed playing around with these affordable pads and would recommend anyone else with Grados perform similar explorations. I'm not sure I would go out and buy a pair of Grados just to do so, or if you really want to, get the cheapest pair you can. To partially address the initial question this thread posed: I personally am glad Grados exist as the SR80i was the first headphone I bought seeking better audio quality. I moved onto the HD6XX a few years later, which is better in almost every way, but I'm not sure I would have done so without first being exposed to the Grados. The potential for changing the sound just by swapping pads is probably unmatched as well. I feel some Grado models qualify as Veblen goods, which I don't personally agree with, but is more palatable when they produce models all the way down to what many would classify as 'cheap'.
N.B. I also have a set of the original SR60 heaphone (flat cup before the mushroom-cup 'i' version) which I was going to post measurements of but it has the most ridiculous 5kHz peak. It's a shame as everywhere else it's better than the later SR80i: lower in the 2-3kHz range and better extended treble above 10kHz. Can anyone confirm this is a typical feature of the early Grado models, or just my copy (I got it second hand only recently).