A new iPhone

I got a brand new iPhone 8 Plus to replace my other one whose cable was or was found to be broken when replacing my battery.  So, for a $49 battery replacement charge, I got a brand new identical replacement phone, which may be good for a few more years, straight from an Apple Store.

Long on my mind had been "how badly were the microphones, which I rely on for RTA, doing?"

I had played rattling loud over the speaker/microphones a number of times for inability to hear otherwise.  There had not been any deterioration in playback.  But what about microphone performance.

On quick examination, the answer appears to be "none to speak of."  The new phone seems to be showing essentially identical RTA responses as before.

I measured a series of RTA's starting close to the chair back (which tends to emphasize deep but not deepest bass) moving forward by one iPhone length (1 iPhone 8 Plus length is what I now consider the standard distance from my ear to the chair), and then repeating that, and then moving forward by another length, and repeating that.

There's also A LOT of variability in measuring the same thing twice probably because of minute differences in position and ambient noises.  So don't take anything that you don't see twice very seriously.  But notice the lump now circling 1 kHz.  Because a pre-1kHz lump previously existed, followed by a slight depression at 1kHz and above, followed by my "engineered" drop, I filled in that natural depression at 900 Hz and above with two 1/6 octave boosts, which vastly improved the musical quality, but one wonders if that 1kHz boost would have been needed if the below 1kHz peaks were instead removed, etc.

Anyway, I still see that critical below 900 Hz peaking, followed by my engineered solution for it.

(After studying these graphs, and listening, I decided to boost the subwoofer DAC level from -11dB to -9dB, which I think is higher than it's been for months or more at least.  It still retains that "electrostatic bass" sound, but just a bit more full at the listening position--which still sounds a bit thin because of longstanding issues with room modes, speaker positions, and other things hard to change.  But that bit has been getting smaller and smaller.  Meanwhile the rest of the room even more too bassy.  A longstanding and difficult problem I am always thinking about.)

At Chair Back

Approximate Ear Position

Another Ear Position

Two "phones" from chair

Two "phones" from chair

The downward sloping is by choice of the Acoustat 2+2 HF control (midway) and by 3 upper midrange EQ's which each made it sound better.  I believe the rolloff is necessary to create the correct ambient sound perpendicular to the opening of the ear canal as it would in a free field.  Basically Linkwitz's explanation of the gundry dip...but I see it as applying to all frequencies 2kHz and above and possibly as a something like 3dB/octave rolloff above 2kHz (when you have line source dipolar in the near field as I do).  With no EQ it's wiggly but flat to 17kHz, then nose dive (without supertweeter).

I need to revisit these and many other EQ subjective issues and so I have finally liberated one Behringer DEQ 2496 from the bedroom (where it is now replaced by a miniDSP OpenDRC and an E30 DAC which I didn't wait too long for after all) for use in new EQ experiments in the living room.

Some will employ the separate aragon power amp as I did with the analog EQ, and some will be piped in the digital circuit ether before the miniDSP's or after the midrange Behringer.

Here is what the earlier 5 year old iPhone 8 Plus measured last month with the same EQ I am using now (or perhaps the highest one was missing in one channel, leading to a slight peaking around 9k).

Actually, it does seem to have more rolloff above 16k (I may have upped the supertweeter level in the interregnum) and a somewhat broader pre-1Khz peak (though it looks like the first "two phones from chair" spectrum...positions weren't documented).

Today's measurements were made with the supertweeter DAC set to +10dB (possibly was previously +6dB) and Subwoofer DAC set to -11dB (I have subsequently changed it to -9dB for better sounding bass).