Penon - FAN 2

> I have also seen some reviewers claim that they criticized an IEM or gave one a less than stellar review and were cut off from further review units. Just to add a citation to this, today I found out that Tone Deaf Monk is one of those people. He covered it in a recent review and brought receipts: https://www.youtube.com/watch?v=5VuAZhghlfA&t=249s I don't know if it's happened to other reviewers as well, but it certainly seems like the niche group of people reviewing Penon stuff is at best a bit of an echo chamber. I'm now highly sceptical of them because of my personal disappointment with the Fan2, which does not sound at all like it was described in various reviews and people I asked about it on Reddit. There weren't many graphs of it back then, but looking on squig.link now, it's clear that it has no treble extension past about 8-10kHz (especially if you account for the 8kHz resonance peak on 711 couplers, which I didn't know about back then). So it's missing a whole octave, and that's exactly how it sounds. TDM was one of the people who described it as "very neutral", which is a lot of crap. It's quite dark and bassy, as you'd expect with the top octave missing. I'm hoping Omar (Audio Amigo) does a big Penon/ISN round-up at some point, because I trust his impressions. They do have some interesting driver architectures, particularly some affordable ISN stuff. But the marketing is definitely a bit sketchy.

I can't tell you what higher end sets with BCDs sound like, because I haven't tried any. However, following a lot of reviewers a few have remarked that the characteristics of a BCD are basically the same regardless of which IEM it's in. As I wanted to try it out without wasting loads of money, I bought the KBear KB02 to see if it's just a gimmick. You can pick one up for about $20 and I'd advise doing that just to get a sense of what it's all about, even though the higher end implementations may be a bit subtler, it will give you the basic idea of what the BCD actually does. My conclusion is that, at this time, it's a gimmick like 3DTV that will probably have died off in a year or two. The main characteristics of the KB02 are: it has a weird resonance that causes "robot voice" on some vocals, caused by the BCDs vibrating. You can also make the BCD vibrate by tapping the shell, which sounds like a spring. The BCD only kicks in within a narrow frequency range, so the effect is quite track-dependent. I believe some higher end ones have less of a contrast than the KB02 but the KB02 highlights what's *actually* going on. It can be fun on some tracks and I'd recommend buying one for $20 just to try it, but I wouldn't recommend it as a $20 IEM. It's mostly not good and sounds like you're listening to music at a party in the next room from the speaker system. There are some IEMs that say they are using bone conduction, but actually use PZT drivers (piezo-electric - same thing you get in novelty xmas cards; normally used for supertweeters & have a reputation for sounding harsh). I haven't yet seen a technical explanation of how these PZTs work, how they're different to a normal PZT or BCD, and if they're even true bone conduction in the first place. The Thieaudio Origin is the only IEM with bone conduction I'm aware of that seems to get consistently positive reviews. I believe that's a true BCD, operating over wider frequencies and at a lower level than the KB02, so it's a bit more subtle. Someone posted to say they were getting the springy noise from one earpiece but not the other, so I guess they must be doing something to reduce that effect, with some QC issues. The Penon Fan3 also tends to get good reviews, including one from Audio Amigo who I consider trustworthy, but I'm a bit suspicious of Penon/ISN. Most of their reviews come from a small group of "fans" and the Fan2, which I have, sounds nothing like the reviews that made me buy it. AFAIK there's no "old gen" and "new gen" it's just BCD vs PZT. The actual BCDs are basically a DD with the diaphragm replaced by a metal weight, which causes the shell to vibrate. I've seen a video of Hi-Fri taking one apart. Unfortunately he seems to have retired from audio, so probably isn't going to do a comparison with the PZT drivers and I'm not aware of anyone else consistently taking apart IEMs to analyse the drivers. My view on BCD is it's probably going the way of 3DTV, but I'd give it a year or so to let the dust settle and see if it ends up becoming a standard thing like subwoofers in a hifi system. It could go that way, but at this stage it's not mature enough or well-understood enough. And the effect varies a bit from person to person depending on the amount of shell contact with the ear, stiffness of eartips used, etc., so it's hard to know to what extent people are actually experiencing the BCD. Especially in cases where people say the only thing it does is make the soundstage wider (since that's just a psychoacoustic effect you can achieve with some EQ).

That's interesting, as the Fan2 experience was one of the main reasons I stopped watching TDM. He describes it as very neutral and it's nothing like that. I also can't be bothered trying to get through his incredibly schizophrenic style of reviews. Even Akros rambling for 45 minutes at least sounds somewhat coherent without a jarring transition every 20 seconds. The Fan2 does have some unique qualities, so I can see how some people might like it, especially if they have high frequency hearing loss. It's very dark and bass-focused, but also quite clean sounding (nothing like neutral though). But according to several measurements on squig.link it has no extension past about 8-10kHz, so it's literally missing a whole octave. And it does sound like that. I just searched his channel and found *[ISN EBC80 Lush, Musical with Crazy Technical Chops 4K](https://www.youtube.com/watch?v=5VuAZhghlfA)*, which is from 3 weeks ago. He does talk about this, so I'm going to watch that. Have you got any more links about this? Especially if he made a video about it at the time, because I missed this and I couldn't see anything obvious in the search results.