Best 24 Bit IOS Audio Interface for Live Guitar

Started by Elantric, December 14, 2013, 04:13:00 PM

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Elantric

#25
Ive tried the Scarlett 2i4, using all the above techniques

but so far cant get it to work with any of my iPads   - will report any progress, since its a nice box with all the features one could want in a small iPad interface (except no SPDIF I/O) 

Seems dumb that Focusrite does not include 5 pin MIDI I/O on any of their IOS interfaces
http://us.focusrite.com/ipad-audio-interfaces

Its beautiful thing to have a nice 24 bit Audio box with  MIDI I/O that works with iPad without all the monkey business of specific device  power up sequencing  -Scarlett 18i6 and 18i20 both work great when used with Apple Camera Connection Kit ( CCK) - no need for a powered USB Hub - but of course both these do require a separate AC wall wart to power them - so they are not true battery powered mobile, and they need to be temporarily connected to a Mac/ PC first, to run the Focusrite MixControl App to  have their inputs selected to Instrument Level and then stored - before using with iPad. Luckily this only needs to be done once, since the Scarlett 18i6 and 18i20 can save their settings in internal flash memory.

Ringleader

#26
So maybe the Scarlett 2i4 is not class-compliant? That is what is so confusing about the Focusrite stuff. Some devices are class-compliant and others aren't and it is difficult to know which ones are.

Take a look at this link. Under the "Connects to iPad" column, some are listed with 30 pin and others list with CCK and the 2i4 just says "No." It seemed like this connects to ipad colume then means class-compliant, but not sure.
http://us.focusrite.com/audio-interface-comparison-chart

Elantric

Its Class compliant works straight away on my Mac with no drivers - but it seems it really needs a beefy 5VDC well regulated  supply current, so will explore using a better powered  USB 2.0 Hub.

Ringleader

#28
I have been wondering about bit depth. There are several variables when considering bit depth, and I'm wondering if anyone here can clarify. As I understand it, there are potentially 4 (or more) variables.

Input converter bit depth
Internal processor bit depth (interface)
Audio bus bit depth (interface)
Audio bus bit depth (software)
Output converter bit depth

For example, the input converter in a Zoom G3 is 24 bit. The internal effects processing are 32 bit. As an audio interface, it only supports 16 bit. But then the output converters are again 24 bit.

This is confusing when trying to determine which specs actually matter! The 16 bit audio interface limitation is the obvious bottleneck, but does it matter when using it with an iPad as an interface with JamUp? Can JamUp (or any other iPad based audio software) even process audio at 24 bit?

All I know is this... when I compare my Apogee ONE (24 bit throughout) to the G3 they both sound good when the guitar is volume all the way up. But when rolling back the volume on the guitar the Apogee sounds noticibly more transparent and cleans up better. The G3 adds a bit of a strange treble boost when rolling back the volume. But is this a result of bit depth or just better converters?

Elantric

#29
Audio bit depth
http://en.wikipedia.org/wiki/Audio_bit_depth

How to Test your Audio Interface Bit Depth
https://www.vguitarforums.com/smf/index.php?topic=10663.msg77346#msg77346

AKM makes most AD/D/A used todays
http://www.akm.com/akm/en/product/detail/0019/


There are several principal chipsets that are in play in most DSP audio processors that support live USB Audio Streaming.

1) the initial A/D convertor that captures the analog audio. Higher bit rate, the more detail, headroom, and dynamic range with immunity to hiss and noise 24 bits remains state of the art,

2) while 32 bit output DACs are just now appearing from the vendors, 24 Bit D/A remain the dominant type used.

Often these are combined is a single IC known as a CODEC.
http://www.akm.com/akm/en/product/detail/0020/

The DSP often uses higher precision 32bit or 64 bit math  - but will have 24 bit PCM I/O using I2S format
http://en.wikipedia.org/wiki/I²S


But there's  separate USB Audio streaming IC, and this is often the bottleneck, many only support 16 bits I/O -  while the more expensive ones support 24 bits.

http://www.ti.com/paramsearch/docs/parametricsearch.tsp?familyId=463&sectionId=630&tabId=2701&family=analog&uiTemplateId=AUDIO_PRDSRCH_T

Most manufactures will Hype that they have 24 bit A/D , or 32 bit DSP,  but hide the fact that only 16 bit audio passes thru USB.

For example all Zoom Audio products only support 16 bit Audio over USB 

QuoteCan JamUp (or any other iPad based audio software) even process audio at 24 bit?

Yes -  iPads running IOS7 support 24 bit @ 44.1K or 48Khz

http://auriaapp.com/forum/viewtopic.php?f=19&t=9356

Ringleader

So the real benefit in regards to being a guitar interface is the A/D and D/A converters being 24 bit? That is where the most noise and artifacts are going to show up right?

Anyone know if JamUp processes at 24 bit? I couldn't find this info.

Elantric

#31
Yes all Positive Grid apps as well as most other IOS guitar apps work with 24 bits today.the internal CODEC IC  Apple uses for mic in and stereo headset out on Ipad/Iphone runs at 24 bits.
https://discussions.apple.com/message/12026245#12026245
But the iPad / iPhone's noisy Mic pre and I/O crosstalk using ANY Guitar  / Instrument interface that employs the iPad / iPhone's 4 conductor TRRS 3.5mm Headset Jack connection = white noise, and high susceptibility to high pitched feedback on high gain Amp Sim patches. So avoid these interfaces : iRig, iRig Pre, Peavey AmpKit, Positive Grid Jamup plug, Positive Grid BT-4)
http://www.positivegrid.com/bt4/

Its not a trivial difference either, once you hear a dock connected (or CCK USB connected) instrument audio interface running at 24bits A/D and  D/A with low latency you will never touch your old 16 bit interface - and will toss all your TRRS 3.5mm Jack  headset connection interfaces in the Trash. For this reason i find it laughable and worthless for 2014 products like IK Multimedia iLoud, or Roland Cube GX amps to provide built in worthless iPhone / iPad TRRS 3.5mm Jack  headset connections

Heres my list of Ipad guitar interfaces - best to worst.

1 Focusrite Scarlett 18i6 (24 bit )
2 Irig Pro 24 bit

3 Line-6 Sonic Port VX

4 Sonuus I2M (16 bit)

5 GRIFFIN Studio Connect 16 bit

6 Behringer IS202  16 bit

7 Original iRig ,

8 Peavey Ampkit (connects via Headset jack)

Ringleader

#32
My best sounding interface is the Apogee ONE. It sounds great and has a dedicated output which I think also makes a significant difference as opposed to my Apogee JAM which uses the iPad headphone output. Actually surprised the iPad headphone out is 24 bit though. I would have never guessed that.

But, all things considered, I still think the best iPad audio interface for strictly a guitar player is the Zoom G3/G3X via USB and a CCK. iOS stompboxes still aren't really "there" yet and the Zoom gives you up to 8 great sounding stomp box effects in front of any amp model you use in the iPad. The univibe and tape delay effects are worth it alone. The univibe in JamUp sucks as it adds horrible latency.

And you get stereo 1/4"s outputs and an XLR out for going straight to the board, it is powered by a USB hub (batteries operation does not work when using as an iPad interface), has a tuner right on the floor, 24 bit converters (but not audio bus - see above) and it is CHEAP when you consider all you get when compare it to other options. I got mine for $75 and that is just ridiculous bang for buck. If they came out with one that was all 24 bit and offered bluetooth and more midi functionality, it would be game over.

Elantric

#33
QuoteMy best sounding interface is the Apogee ONE.
Agreed - Most  Apogee Interfaces are considered the top  / best in class for iPad/ iPhone. (only surpassed by RME)  I would own one, but I find I get similar 24 bit I/O USB performance using Focusrite Scarlett series at half the cost of Apogee.

One major problem with Zoom G3 / G3X - the AD/DA converters are 24 bit, but the G3/G3X USB I/O is only 16 bit ;(

more details here:
Re: iPad as portable recording studio
https://www.vguitarforums.com/smf/index.php?topic=7831.msg55321#msg55321



IPad/iPhone 24 bit Audio / MIDI + FTP and more on Battery power
https://www.vguitarforums.com/smf/index.php?topic=10323.0


EDIT:

I finally located a gently used 2005 Digitech GNX3000 - and Surprise - its makes a fantastic iPad Audio Interface with clean preamp and full 24 bit Audio I/O and working 5pin MIDi Interface for iPad+CCK! 
https://www.vguitarforums.com/smf/index.php?topic=8291.msg80295#msg80295


rolandvg99

Atm I use the Behringer IS202 with my VG-99 and loopy HD. I use the AUX 3&4 input fed by a FIIO DAC from the VG SPDIF out. Due to some dodgy design flaws by Bejronger (and IOS7 audio hickups) I use the iPad output instead of the IS202 outputs. The Behringer works great as a hub for outboard gear and MIDI, but its preamp and DAC section is sub par.
To V or not to V: That is the question.

My little Soundcloud corner

Elantric

#35
The ipad will not slave to an external SPDIF Input - although many try
http://www.kvraudio.com/forum/viewtopic.php?t=359018&view=previous


My day gig i design Cinema Audio processors
www.uslinc.com)
and every one of our products with SPDIF or  AES/EBU Digital Audio input employs hardware Sample Rate Conversion (SRC) IC's (AKM AK4122).

These chips are trivial today and are $9/ea

Yet there remains a large populace and global mindset that hardware SRC's are too expensive and not worth the time to implement in USB audio interfaces for pros or consumers , since Sample rate conversion can be accomplished with higher precision non real real time using a software SRC running in Windows or OSX.

in 2014 - I cant find a single USB Class Compliant Audio Interface that includes a built in Real time SRC function to accept digital audio from other gear.   

And I find it just bone headed that we live with the paradigm of anytime you want to record an external device using Digital SPDIF, your entire DAW is now being clocked by the external device supplying the SPDIF signal. Forces you to pre-plan if you run 44.1kHz or 48kHz and not 96kHz / 192kHz before you record a single track - simply to accommodate the available SPDIF clock rate of a third party digital audio source.     
I was spoiled with my 1997 Sonorus STUDI/O that had a built in real time hardware Sample Rate Conversion on one of its optical SPDIF inputs.
http://web.archive.org/web/20140106150119/http://sonorus.com/


Too bad  old Roland M-1000 Digital Mixer is Not USB Class Compliant - else it could have been the perfect iPad Audio interface for VG-99 or other gear with a 24 bit SPDIF out
http://www.roland.com/products/en/M-1000/

     

DeRigueur

Quote from: Ringleader on January 07, 2014, 09:33:51 AM
I still think the best iPad audio interface for strictly a guitar player is the Zoom G3/G3X via USB and a CCK.

Will the GR-55 usb work like this as an iPad audio interface?
Fender GC-1 -- Boss SY-1000 -- Alto TS112A

Elantric

#37
QuoteWill the GR-55 usb work like this as an iPad audio interface?
No  - iPads require USB Audio Class Compliant hardware (which the VG-99 / GR-55 are not)

rolandvg99

#38
The VG-99 works with the CCK if the USB setting is set to "Standard" and not "Advanced", but it is useless as a playback device if one plan to change patches due to output muting. MIDI does not work in "Standard" mode either. Page 72, VG-99 user manual.
To V or not to V: That is the question.

My little Soundcloud corner

Elantric

#39
QuoteThe VG-99 works with the CCK if the USB setting is set to "Standard" and not "Advanced", but it is useless as a playback device if one plan to change patches due to output muting. MIDI does not work in "Standard" mode either. Page 72, VG-99 user manual.

True, but for VG-99, I understand its 16 bit Only for USB Audio when in "Standard Mode", and the hardwired Audio Mute (with a gap of silence for USB Audio playback) on every VG-99 patch change presents deal breakers for most.

rolandvg99

Correct Steve. 16-bit only, but beats going analog out to a cheap interface for recording. If one can't afford a claas compliant soundcard with a price tag above $100 this is still one of the better options for recording the VG to an iPad.
To V or not to V: That is the question.

My little Soundcloud corner

BackDAWman

Quote from: Ringleader on January 07, 2014, 09:33:51 AM
My best sounding interface is the Apogee ONE. It sounds great and has a dedicated output which I think also makes a significant difference as opposed to my Apogee JAM which uses the iPad headphone output. Actually surprised the iPad headphone out is 24 bit though. I would have never guessed that.

But, all things considered, I still think the best iPad audio interface for strictly a guitar player is the Zoom G3/G3X via USB and a CCK. iOS stompboxes still aren't really "there" yet and the Zoom gives you up to 8 great sounding stomp box effects in front of any amp model you use in the iPad. The univibe and tape delay effects are worth it alone. The univibe in JamUp sucks as it adds horrible latency.

And you get stereo 1/4"s outputs and an XLR out for going straight to the board, it is powered by a USB hub (batteries operation does not work when using as an iPad interface), has a tuner right on the floor, 24 bit converters (but not audio bus - see above) and it is CHEAP when you consider all you get when compare it to other options. I got mine for $75 and that is just ridiculous bang for buck. If they came out with one that was all 24 bit and offered bluetooth and more midi functionality, it would be game over.

So do you plug your guitar into the Zoom and via USB/CCK into the iPad. Forgive me if this sounds like a dumb question. How do you route your audio into BIAS and then back out and into the Zoom's effects?

If this is so that gives me an idea.....

I'd have an awesome amp simulator and access to the Zoom effects Cry Wah and Harmoniser which I love and use in a couple of our covers!

Elantric


Set the G3 Amp Modeling Off, control the USB Direct /DAW mix in config setting seen below 


The Zoom G3 / G3X requires a powered USB hub inserted between the iPad with USB camera Connection Kit (CCK)

However the iPad sees the Zoom G3/ G3X as a 16 bit interface - so the $40 Griffin Studio Connect  (also 16 bit) works a bit better IMHO, since it powers the iPad too.

http://www.sweetwater.com/store/detail/StudioCon?utm_source=Google&utm_medium=PPC&utm_campaign=none&device=c&network=g&matchtype=&gclid=CLHh2sy87bsCFUQ6QgodV20AhA


Ringleader

#43
Regarding the 16 bit thing, the converters in G3 are 24 bit so lower noise higher dynamic headroom, it is only 16 bit in the audio interface which you stated wasn't as crucial. The Griffin is 16 bit converters and 16 bit audio interface so G3 is better + up to 8 effects built in.

G3 effects only come before iPad amp sims, not after.
GTR > G3 effects > iPad apps > G3 outputs

Set 100% mix to DAW when using G3 effects so all signal goes to front of the iPad amp sim.

cooltouch

#44
Say Elantric, if you figure out how to get the Focusrite 2i4 to work right with your iPads, let us know, okay?  When I finally get my iPad, I'm gonna need a decent audio interface for it, and the 2i4 was at the top of my list. You mentioned the 18i6 and 18i20 as working fine with a wall wart, but geez that's all kinds of overkill for me.
Best,
Michael

Elantric

#45
QuoteSay Elantric, if you figure out how to get the Focusrite 2i4 to work right with your iPads, let us know, okay?
Read Here for details on how I got this working!
How to Use Focusrite Scarlett 2i4 + Fishman Tripleplay with iPad on Battery Power
https://www.vguitarforums.com/smf/index.php?topic=10323.0

Quoteit is only 16 bit in the audio interface which you stated wasn't as crucial.

Yikes! Point out where its implied I said anything like that. Any 24 bit reduction down to 16 bits Anywhere is always going to result in audio with 35-50 dB Less dynamic range, due to the much higher background noise floor.

Old timers can relate, today for my ears:

* iPad Guitar Audio Interfaces that use a 3.5mm TRRS 4 conductor Plug to connect to the iPad running Bias/ JamupPro XT offers all the fidelity of a 1967 Lloyds Cassette Recorder with No Dolby / No DBX Noise reduction, using a K-Mart telephone voicemail Tape.   - (yes i hear that much hiss )

* iPad Guitar Audio Interfaces that use a 24 bit A/D, but only a 16 Bit USB Audio Path to connect to the iPad running Bias/ JamupPro XT offers all the fidelity of a Aiwa FX-990  Cassette Recorder with  Dolby C, using Metal Tape.   - (Yes hiss is there, but much lower )

* iPad Guitar Audio Interfaces that use a 24 bit A/D, and 24Bit USB Audio Path to connect to the iPad running Bias/ JamupPro XT offers all the fidelity of modern stand alone DSP Amp Modelers . Its better than a GT-100, and reaching towards Kemper Profiler sonic bliss territory


http://www.analog.com/en/content/relationship_data_word_size_dynamic_range/fca.html






At this hour I can only recommend iPad / iPhone  Guitar Audio interfaces which provide 1Meg Ohm Instrument Input and full 24 bit PCM I/O

While there are many options, I currently achieve this with:

* Focusrite Scarlett 18i6 (No Powered USB Hub Needed)

* Presonus 1818VSL (Powered USB Hub Needed)

*  used 2005 Digitech GNX3000 - and Surprise - its makes a fantastic iPad Audio Interface with clean preamp and full 24 bit Audio I/O and working 5pin MIDi Interface for iPad+CCK! 
https://www.vguitarforums.com/smf/index.php?topic=8291.msg80295#msg80295


IPad/iPhone 24 bit Audio / MIDI + FTP and more on Battery power
https://www.vguitarforums.com/smf/index.php?topic=10323.0

Elantric

#46
QuoteSay Elantric, if you figure out how to get the Focusrite 2i4 to work right with your iPads, let us know, okay?
Will Do! Its a nice box!
I suspect there is an issue with momentary in rush current overload, which the Ipad dock port hardware senses and pops up the Accessory uses excessive power Error message. That happens anytime the initial USB connection sequence occurs in the wrong order, if you continue to re-attempt to connect things in the wrong order a few times in a row, the iPad's internal Dock Port USB UART's thermal protection will shutdown and disable the iPad dock port. This often requires the iPad to be completely powered down, wait a few minutes and then after re-power up, finally (if you are lucky to discover, use, and remember the correct iPad Dock / Powered USB Hub, USB Audio Interface connection sequence) the iPad finally shakes hands and allows external USB Audio connections. Its when you do things in the wrong sequence, it can take several minutes before things will ever work again - so remember this as a potential disaster at your live gig.   


Ringleader

#47
Quote from: Elantric on January 07, 2014, 09:44:08 PM
Yikes! Point out where its implied I said anything like that. Any 24 bit reduction down to 16 bits Anywhere is always going to result in audio with 50dB Less dynamic range, due to the much higher background noise floor.

Ha didn't mean to misunderstand, but getting to the bottom of this is why I asked about bit depth in the first place. I thought that since the A/D is 24 bit you would reduce the noise going in and then once the signal is digital it wasn't as crucial for the S/N ratio. And CDs are 16 bit and I wouldn't consider them "hissy."

If you want to offload some of the iPad processing for guitar effects, I still think the G3/G3X is great bang for buck as a utility and at the moment there is no 24bit throughout guitar processor that also acts as an audio interface for the iPad that I am aware of. Maybe at NAMM something will be released, and maybe the DigiTech RP360 will be 24 bit throughout.
http://www.thegearpage.net/board/showpost.php?p=16470442&postcount=29

DeRigueur

Anybody know what the specs are for the Rocksmith guitar cable?
Fender GC-1 -- Boss SY-1000 -- Alto TS112A

Elantric

Id Google it, and click Images see if a schematic pops up.