Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.
Download on the App StoreAudiobus is the app that makes the rest of your setup better.
A few thoughts for those that are into Amp sims
Whenever an iOS app is available as a demo VST/AU plugin too. Do yourself a favour and download a copy of DDMF's PluginDoctor. It will show you exactly what's going on with regard to stamped in EQ curves and harmonic distortion. The demo of PluginDoctor is more than adequate for the task. The only limitations are that you can only test one plugin per session and that it occasionally has a 30-second nap (if you don't want to wait, simply close and reopen the app, it will only take a few seconds).
Below you'll find a bunch of screenshots comparing a clean amp in Softubes Vintage Amp Room and Klevgrand's REAMP (which sit at the base of STARK too). The top two are from REAMP and the bottom two are Softube (first is the default EQ curve. They were recorded at a sample rate of 48k
What you can see is radically diffent approaches to modelling with regards to the default EQ curve modeling but more worrying you can clearly see that REAMP has a problem with aliasing. That's shown by the harmonics on the far right that are folding back on themselves. And don't forget that that's with the Amp in its default state so if you want to brighten things up because the default EQ curve cut's the frequencies over 10k so dramatically, you're going to multiply those nasty aliasing artifacts even more.
Both Vintage Amp Room and REAMP have a similar processor overhead but Softube uses both oversampling and filtering to ensure that it's alias-free when working at 44.1 or 48K. The only way to ensure that REAMP is alias free is to run it at a sampling rate of at least 96k but you're probably talking more like 192k to remove all aliasing.
There's a lot of very subjective opinions when it comes to amp sims but it's good to apply a little science so you at least can see what your amp sim is actually doing to your source audio before you even begin to tweak it's settings.
The fact that REAMP aliases doesn't make it a bad product (I personally think its great when used in moderation). But knowing that it aliases and seeing the default EQ curves can help you achieve better results.
This post isn't intended to dis Klevgrand. I think many of their products are great, but I've seen a lot of very subjective views shared this week in the various STARK threads so thougt it might be useful to share something less subjective with regard to any product that adds harmonic distortion, not just amp simulations.
Comments
Aliasing is a regular feature of all digital audio processing, and always present.
The only difference with sample rates beyond (iirc) 72khz is that the aliasing products fall into a range of the spectrum that isn't hearable (by humans).
That's the difference you hear with a 96 khz sampling rate, it's NOT that sampling is more 'precise' at that rate. The sound seems more clear and well defind because aliasing foldbacks are disharmonic (in regard to the musical content) and thus perceiveable despite their low level in loudness.
To avoid this disturbance there's always an anti-alias filter to suppress this effect.
Good filters for 44.1 khz are quite demanding (expensive), that's why a lot of home entertainment systems are based on a 192khz sampling rate.
It's common use today to apply a higher sample rate temporarily on critical digital audio processes (like filters) to improve aliasing performance - this is called (internal) oversampling.
Again it's easy to tell by ear if that process has been applied or not.
I don't know what process the diagrams display, but no guitar cabinet will emit much content beyond 8 khz, the driver acts as a natural filter by it's mass.
It can't move fast enough to transmit frequencies beyond that range.
But more important: such diagrams don't tell anything about sound because only the loudness of frequencies are pictured, not their performance in time.
The human ear is WAY more sensitive to time aspects of sound than to loudness.
You can immediately tell a dry sound from a copy that got some reverb, but you'll have trouble to identify the louder one of 2 sounds if the difference is only (say) 10%.
I'd rather suggest to use your ears instead of diagrams, they can be very misleading.
I'd suggest it's a mix of both. The visualisations from a tool like PluginDoctor are useful as they can show you how the plugin is achieving its results. But you, of course, should make your final judgments based on what your ears are telling you. As long as you realise your ears can fool you.
The tests in PluginDoctor do a bunch of simple things (I'll copy paste from the manual so there are no intermediary translation issues). I've highlighted the two tests I used here but detail the other test's as a summary.
Linear Analysis: This input signal contains a flat contribution of all admissible frequencies, i.e. if you would send this signal through a frequency analyzer, you'd get a flat curve when looking at the magnitudes of the contributing frequencies, and also a flat curve when looking at the phase response. This means that all deviations from a flat
curve come from the plugin being analyzed.
Harmonic Analysis: In IMD mode (which is what I generally use) PD uses two input frequencies, a low and a high one, with an intensity difference of 12 dB, i.e. the lower frequency comes in a 0 dB, the higher at -12 dB. The lower input frequency is set to 60 Hz, the higher frequency to 7000 Hz. If the plugin is creating additional harmonic content, this will now not only show up in higher harmonics of the two input frequencies, but also in modulated peaks of the higher frequency by the lower one: you will see a peak at 60 Hz, a peak at 7000 Hz and, if there is intermodular distortion, several peaks at 7000 +- N*60 Hz. Plugindoctor calculates a numerical value for IMD by dividing the RMS-summed contributions of 10 modulated peak lower than 7000 Hz and 10 modulated peak higher than 7000 Hz (all peaks with a 60 Hz distance between 6400 Hz and 7600 Hz) by the magnitude of the incoming 7000 Hz peak.
There are other tests such as Performance which reports both CPU and Latency, Dynamics, which has tests specific to compressors/limiters etc and an osciliscope which is brilliant at showing whether your source material is being squashed unintentionally (particualrly useful when anylizing compressors but allso distortion plugins).
It also allows you to analyse hardware.
By the way, the tests I did where with REAMP not STARK.
PluginDoctor is a product created by DDMF, who are already well regarded as an iOS developer but they have an excellent reputation going back a good number of years with regard to their desktop plugins. They were partly responsible for exposing the large number of plugin developers making bogus claims regarding their EQ products (especially with regard to harmonic distortion, when the plugin added no harmonic distortion).
Using a product with significant aliasing will cause artifacts if you don't compensate for it. Where it can become particularly troublesome is when you have multiple instruments that exhibit aliasing issues and you then master with an EQ with its own aliasing problems. The compound effect can sound bad - not speaking subjectively here, we're talking bad, meaning bad!
But the main point of these tests is simply to put the artist/creator/engineer in control so they don't add to an existing problem. It's no replacement for a good set of ears.
Geekery at it's finest
Guilty as charged!
You guys are obviously very experienced in working with digital audio.
I am not. I mainly rely on my ears and personal judgement.
But, these discussions are very enlightening, if you can get past the initial confusion.
I understand that visual feedback can be misleading, but it definitely helps when trying to comprehend digital audio processing.
Thanks for the knowledge, discussion, tests, and visual aids.
It is much appreciated.
I think where visualisation really helps is in giving a common reference....we all hear things differently don't we ? For many different reasons...including our own ears or what we are listening on....visualisation is constant if it is in an exacting form like lines on a graph with a scale...a spike at 2khz looks like a spike at 2 khz to everyone, but not everyone would hear it exactly the same.
Interpreting, understanding and knowing what the visualisation actually means is the trick though, that requires us to associate what we are seeing with what we are hearing with the visualisation maybe suggesting why we are hearing something a certain way.
Does Plugin Doctor come with different colour schemes? I'm personally partial to blue.
There’s some great feedback about this stuff on the Harrison Mixbus forums and a few other well referenced blog posts — very interesting reads too.
The Mixbus channel saturators also alias, and it is very easy to reproduce/observe/hear this with sine waves, eqs and whatnot. The interesting parts of the debate are related to the proving of how in practice (in real musical/mixing contexts) that this doesn’t matter a bit and the aliasing frequencies are so microscopicly imperceptibly quiet that they won’t ever make a tangible difference in the mix, providing you simply keep in consideration that it can happen and make your mixing decisions accordingly.
Mixbus is well regarded as one of if not THE best sounding DAWs, due to its propetary console modelling DSP (which those saturation units are a part of) — the Harrison engineers have thus far decided that removing the aliasing wouldn’t be beneficial, and that tells you a little insight about the actual practicalities it has on real life audio engineering!
It's funny I've always thought of Mixbus as the emperor's new clothes.
Aliasing in and of itself isn't necessarily a bad thing. Most digital instruments of the 80's and 90's alias, and in quite extreme ways. A couple of my favourites, the DX7 and PPG Wave are particularly bad when it comes to aliasing.
And with analog emulations such as those from U-he, I often like the low-quality version of the patches more than when the oversampling is set to overdrive - as in up to 11, not distortion overdrive!
The important thing is being in control of what you're hearing. And knowing what factors make what you're hearing a timbre that you either like or dislike.
Watching that Roland documentary this afternoon (linked to it in another thread), reminded me how creativity in popular music culture has come out of musicians blindly misusing and actively abusing the original design intent put into the instruments and FX they use. There is no wrong or right, good or bad or other subjective value we as musicians should pay any regard to. But a little geekery and understanding of how digital audio works is no bad thing. You're still free to go with your heart and ignore what the charts are telling you...
But seriously. I'm with @CracklePot on this one. If the sound grabs me I really don't care why. Still can totally understand the process of visual comparison. Spectrum analysers have helped me many a time to correct my mixes. Thanks for posting this @jonmoore
EDITED WITH STARK SETTINGS: There's a Mac Demo "Spark" so I ran it and made these PlugInDoctor images.
AMP: "American Guitar 2" CAB: "Bypass" ROOM: Normal FX SLOTS: Empty
Screen Shot 2019-04-05 at 11.56.07 AM
Screen Shot 2019-04-05 at 12.00.27 PM
I rest my case. I'll await the verdict of the jury.
"If the spike doesn't fit, you must acquit."
If you judge someone by the company he keeps, then I will be proven innocent every time! The company here is first rate.
Even tho my understanding is limited I am starting to enjoy these tech discussions. Maybe I just like the pretty pictures!
A definition of alias, please?
The aliasing is actually worse in those images. It can be seen by the upper harmonics folding in on themselves under the orange line.
This link has a good 101 that's described in plain language.
https://theproaudiofiles.com/digital-audio-aliasing/
Here's the PlugInDoctor images for Amplitube 3 on the Mac:
Screen Shot 2019-04-05 at 11.50.02 AM
Screen Shot 2019-04-05 at 11.51.45 AM
And for a more technical description.
https://www.wikiwand.com/en/Aliasing
Looking for other Amp Sim's on the Mac I found "Guitar Rig 5"
I picked a Fender Tweed Model:
Screen Shot 2019-04-05 at 12.00.27 PM
@McD The better Harmonics test BTW is the IMD test (button top right). That feeds a source signal at 60 hz and 7K hz. This is more akin to a real-world audio signal.
The test you used feeds a single source signal at 1k hz, which can be seen clearly as its the first fundamental harmonic with the extra harmonics getting progressively lower as you go up in frequency.
That's still the STARK image.
BTW Guitar Rig aliases badly too unless you raise the sample rate to at least 96K as does Amplitube.
I take that back ref Amplitube (they must have added internal oversampling), the image you posted shows no aliasing. I don't own Amplitube so I was going on old information.
Check!
Screen Shot 2019-04-05 at 12.16.24 PM
The worrying thing with Amplitube is the really extreme EQ curve that pretty much filters everything out post 5K. That might be the reason for no evidence of Aliasing.
Yet again the aliasing can be seen but it's disguised as the upper harmonics aren't so easy to see. But those mounds in the upper frequencies - if you place an imaginary ruler over them and the peaks are getting lower as you move back from right to left, that's evidence of aliasing.
This in-depth review is better at describing how to get the most out of PluginDoctor as it's worded in plain language, whereas the manual is a bit too engineering/technical.
http://soundbytesmag.net/review-plugindoctor-from-ddmf/
FYI: I think adding Stark to audio in AUM improves sound going through it. If you like what ReAmp does in your mixes then you'll probably love some of the Amps included in Stark.
It might make a good pair with "MicSwap Pro" to supply the extra details while contouring the input's coloring. In complex AU FX configs it adds extra qualities nothing else I've tried does (in the AU listing).
If you only need one instance of an Amp Sim then the IAA products still seem to have better capabilities for guitar tones. As an IOS replacement for Bias or ToneStack (to make modern metal and expensive Amp tones) it's not the "Droid You're Looking For".
While AmpSim might alias, I don't think it's possible to tell from those diagrams that it necessarily has a problem.
I already purchased STARK as I found a way to work with it that works for my typical use cases - Rhodes/Wurlitzer EP's and suchlike.
With REAMP, I use it moderately and always with more than a 50% mix of the original source.
As mentioned earlier, I wasn't attempting to dis Klevgrand's products just shine a little light on what it's doing in a less subjective way.
To explain a little more about the Amplitube Linear Analysis chart. This isn't so worrying if you've dialed in that extreme EQ response but if it's neutral, that's severely mangling the signal before you even get to the harmonic distortion.
You've got a massive peak of +7.5 dB around 200 hz and then it's off the chart between 1-5k (over +10 dB before dropping to nothing. I'm presuming you just picked an Amplitube preset as that's a far from neutral EQ Curve even allowing for the Cab. That's some seriously in yo face EQ!
I just wanted to grab another AU Amp Sim to see what the "tea leaves" would reveal.
Thanks for the introduction to a great tech tool and the concept of "Inter-Modulation Distortion". Those DDMF folks (makers of PlugInDoctor) are the best audio engineers on IOS, IMHO. Their "NYCompressor" AU FX is an amazing product as judged by my ears. Some of the others are so subtle I don't hear the signal changing but NYC can add extreme gain without quality loss and limit without you detecting it's insertion.
BTW if your an existing customer of DDMF contact the developer through his website and he should give you a 50% off discount code for PluginDoctor. I had my offer sent by email, as I own other desktop plugins of his, but I'm sure he appreciates his iOS customers too.
That's if you're hooked enough to spend $10.
The influence of any DSP is always going to be subjective -- I personally find the most 'musical' aspect of Mixbus is the console inspired workflow and how quick/intuitive/insightful that can throughout the production process with regard to mixing decisions.
The compressors on the Bus and Channel strips are brilliant too!!