iPhone 6S plus Vs. iPhone XS Max with MG2

Did I just waste $500? Maybe. I’m a long time 13pinner, a bassist for 45 years with 11 basses that I’ve installed 13pin systems; Ghost, RMC, GK2B, GK3B (internal & external). I recently started playing guitar on some gigs and tried the MG2 app on an iPhone 6sPlus and it blew me away, it tracked some monophonic lines better than my GR and made me want to build an iOS rig. I’m going guitar to iRig Pro, iPhone 6S Plus, with midi control from Roland FC-300 running AUM with MG2 and various soft synths. I could see I was maxing out the 6SPlus so I started shopping the used market. I picked up an XSmax with 4GB RAM and 512GB storage and the A12 Bionic processor for $500 ( just about what used GR-55 sells for). My 6S Plus only had 2GB RAM, 128GB storage and an A9 processor, so I expected a huge leap in performance! But in a word, NOT! With half the RAM and a 5 year old processor, the 6S Plus runs better audio than the XSmax! Both have iOS 13.3.1, both running the same versions of MG2, AUM, i FretlessBass, SampleTank etc… The 6S Plus runs smooth with a 64 sample buffer, while the XSmax hiccups the minute you drop below 128. Latency is much less noticeable on the 6S Plus. Add to that the XSmax will randomly crash MG2, makes it ungiggable. I believe it’s a hardware issue with the A12 and Apple’s current D/A conversion? So I guess the 6Splus becomes the guitar rig iOS device. Anyone have experience with the latest iPad mini 5? I believe it also uses the A12 bionic processer, but the iPad mini 5 retains a headphone output like the 6S Plus, so I’m curious if it has similar D/A architecture and would run smoothly? I also wonder if the iPhone 11 has the same issues as the XSmax? I did a video comparison of the two phones running MG2, AUM, iFretlles and Sampletank. https://youtu.be/UYq3nwchlhI

A/D conversion is done by hardware in your audio interface, so that certainly is not the bottleneck.
We don’t know anything more about that than you, had no reports about this issue so far,
this might be because most users use ipads for running MG.
Maybe your Iphone XS Max is not healthy. Did you buy it new?

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Actually I’m finding a lot of documentation over on the AudioBus forum. I’ve read through these threads and see that Apple is aware of the problem. Consensus seems to be that it is how iOS deals with multi-threading the CPU. Check these links, lots of info on similar occurrences https://forum.audiob.us/discussion/29769/gen-3-ipad-pro-users-have-you-noticed-significant-cpu-spikes and here https://forum.audiob.us/discussion/31820/iphone-xs-users-do-you-feel-stuttering (I didnt buy the iPhone new, $500 is pretty low for a 512GB XSmax, but it seems fit otherwise, none the less it won’t make it on the gig rig, it’ll become my phone and the 6S Plus will play music).


ok, thanks for the info!

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This looks very strange indeed!

Its the same ARM code that runs and the only difference I can think of between the two (besides the much faster CPU in the XS Max) is thermals (which might cause throttling) and the higher pixel count on the XS Max screen (and hence slightly higher GPU load). I don’t believe the latter has any influence here.

Lets be aware of any other experiences like this and try to get a Max phone to test it on, if others report anything similar.

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The A12 has 6 cores, 2 high perf and 4 lower. Some of the discussion on other forums has suggested that iOS recognizes the A12 and relegates audio to the lower cores. That would explain the spikes in the meter on AUM, it reads in the red frequently, while the 6S plus stays under 80% running the same audio configuration. I believe that was from someone who had received a response from Apple.

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the link below is my 3rd video documenting the audio issue with the iPhone XS Max. I chose another app to show it is not app specific. Both phones have the same iOS running the same app. The XS is unable to handle low buffer settings required for live audio performance. The older 6s Plus did not suffer from this problem. While the 6s doesn’t exhibit the cracking associated with small buffer, MG2 did crash a few times on me last night, may have overheated. I wouldn’t trust it on a gig. Anyone tested an iPhone 11 or iPad mini 5 gen?

Just curious… I recently been running my apps with AUM but always have a hard time with sampltank. Always sound glitchy (tracking issues). Audio kit apps work just fine. iPad 6th gen.

I’m able to run SampleTank with lowest buffer setting on my iPhone 6S plus, however if I pile on a lot of sounds SampleTank will just crash before it sounds glitchy, then I reload it. The iPhone XS Max can’t run it or any soft synth at a 64 sample buffer, it just crackles like crazy. It has an A12 processor, is that what’s in an iPad 6th gen?

Looks like those new iPhones have CPUs for performance and CPUs for battery savings on the same processor and audio apps have been associated with the slower CPUs

Please, can anyone tell if iPhone X, XS, XR running IOS 15 still suffers from stuttering on audio apps?

EDIT: a better question would be if Apple products with Chipset A10 and above still suffer from stuttering