InEar ProPhile 8 Measurements and Review (Stream of Consciousness)

I'll try it out. I don't last octave extension is going to matter much in terms of Z out. Once the drivers take a dump, they take dump. +2db or whatever won't help.

BTW, here is the effect of the treble switch. I might leave it on.

 

It's not you specifically. It's collective consciousness. And that I allowed myself to be influenced by this collective consciousness. We can never assume anything about the impedance curve of multi-way BAs.

 

It's not a true impedance curve, but @bartzky produced an impedance reactivity curve for the PP8 before (In steps of 2, 4, 8, 16, 32 and 64 Ohms):



It's not dead-flat, but as far as BA IEMs go it's not the worst offending in terms of Zout pickiness.

 

ProPhile 8 Impedance Curve

 

OK so the above explains it pretty clearly. I wouldn't say the impedance curve is benign.

Assuming ZX2 source impedance of ~2 ohms and Pixel source impedance of ~5 ohms: from the ZX2 to Pixel, I should be getting approximately 0.75db less upper mids compared to 1kHz, and bass to lower mids will be 0.5db higher than the upper mids. This explains why I felt the Pixel was much better tonally than the ZX2 with the ProPhile 8.

As the source impedance goes up, the FR changes in the shape of the impedance curve. The amount is calcuated via a voltage divider. We look at the voltage going through the transducer. Zfreq / (Zout + Zfreq).

The tonal response of the Pixel is definitely an improvement. The issues I've been hearing are minimized to where I can now tolerate them. My gut says a 10 source impedance would be ideal for my tastes. (Need to find my original Sony X). The downside to the Pixel is that the ZX2 is so much better in terms of resolution and refinement of sound. Better tonal response, but loss of technicalites.

The is similar to the Andromeda. where the Andromeda seems to need anywhere from 2 to 5 ohms source impedance for it to be in its sweet spot (not excessively bassy - around 6 ohms it's almost like an UERM tonally). The ProPhile 8 would seem to require 8 to 12 ohms, at least for my tastes.

 

This is speculative, but another factor I think that might be contributing to the dry or shrill upper mids, and also possibly the sibilance, might be distortion. If we examine the distortion plot, there is a simultaneous high point of both 2nd and 3rd other distortion at 2kHz. This means every time 2kHz signal is played (common harmonic of female vocals), smaller but near amounts of 4kHz and 6kHz will occur. The BA driver stuff can be odd at places where 3rd order surpasses 2nd order. Could be grasping at straws...

 

The PP8 on the AK JR is my preferred pairing. I find the combo pretty darn smooth. AK claims 2 ohms OI but I suspect its a little over 3. I think someone on a discord channel measured theirs but I can’t recall for sure.

The bass is my favorite aspect of the PP8. It’s pretty great for armature bass. The midrange has good balance to me. Most times the treble is pretty smooth but every once in a while it gets a little tizzy with some songs. I do wish it had more extension and air, this is definitely the one area it doesn’t hold a candle to Andromeda. But overall, with the AK JR, it’s my go to set up.

 

The Andromeda highs need to be managed with tips that take the edge off and and a source that has a more organic or smoother treble presentation.

I think it would be more correct to say that the Andromeda / ZX2 is highly thought of rather that just the Andromeda.

 

OK, so I finally got the PP8 where I wanted it by doing this. I know, it's cheating, but it works.


I would have used the ZX2, but the EQ on the ZX2 only works with the Sony sound process left on, which results in a strange overly organic DSP'd sound. I believe there are other music players apps for the ZX2 with EQ function, but I wanted to find a reason to use my trusty old Sony X Walkman, which has served me well for years (I still prefer this to iPhone or Pixel). I heard enough of the PP8 from the PIxel phone that I didn't want to give up on it just yet. Running it this way yields these results:

Note plot is an RTA from PN, so 1/3 smoothed.


Basically, what I've done is make the FR more ZX2 / Andro like. I definitely hear the appeal of the PP8 now.

In closing, some thoughts:

• The PP8 has a weightier heftier sound. The Andromeda is lighter and faster. The best way I could put this that it's like the difference between an AE woofer with a heavier cone and Eminence woofer with lighter cone. No judgment here on which is better, I'd like to think each provides its own strengths to the table, with the Andromeda being a more technical listen with better clarity, separation, and speed, and the PP8 being a more romantic listen, with better heft, body, and thickness of notes. This is of course all things being equal with the upper mids of the PP8 being tamed.
• Despite a a few reviews I've skimmed on the Internet proclaiming the the PP8 is neutral, I'd have to vehemently disagree with this assertion if the PP8 is running from lower source impedances (2 ohms or less). The lower mids are just a tad too recessed. The upper mids are excessive and can be fatiguing. This is actually not too different from the UERM (which has a similar response and impedance curve).
• However, I think the UERM (and Andromeda) nails the diffuse field* 2-3kHz bump whereas the PP8 slightly misses the mark with the bump being centered about 1kHz too high. In that respect, the PP8 is actually a little closer to the frequency response of the ancient Yamaha NS10 monitor (what the UERM was supposedly based on) in that region. The Yamaha NS10 monitor was very well known back in the day as being a bright monitor. Modern monitors such as the JBLs, Mackies, Yahama HS series (skip KRK) serve as better references for neutral sound, assuming they are set up properly.
• A solution to improving the frequency response might be to run sources with higher output impedance from 3.5 to 8+ ohms**. Changes will be minor, but even a 1db or slightly less than that across wide frequency ranges here and there will make a huge difference.
• The impedance curve of the PP8 is just as screwy as every other multi-driver BA IEM. Frequency response will be affected depending upon source impedance of amp.

* It's really not diffuse field, it's more that IEMs bypass pinna, we need some pinna gain for IEMs to sound correct.
** I ran the UERM the same way. I did not like UERM from amps with near 0 source impedance.

 

LOANER BEGINS: http://www.superbestaudiofriends.org/index.php?threads/loaner-inear-prophile-8.5230/

 

2db would be about right for bass boost.

It has really just hit me how problematic multi-driver BAs can be with impedance. I don't know enough about IEMs and power dissipation inside the shells, but it seems that it should be trivial for the manufacturers to design crossover networks that present a more even load. There would be some tradeoff of course, loss of efficiency, so maybe not an option.