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PostPosted: Sat, Jun 01, 2019 5:50pm 
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Hack

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Dear Two Notes engineers,

I've recently got C.A.B M and find it simply amazing!

However, I have an issue that substantially limits its usability when used for home recording.

Here is the thing: TorpedoRemote Desktop (MAC in my case) is amazingly user friendly way to control the unit. However it REQUIRES USB connection to the device.
When C.A.B M and recording interface (Focusrite Scarlett 2i4) are both connected to the same MacBook Pro (different usb ports, no hubs) it creates severe usb noise. Disconnect the USB going to C.A.B M and voila - you've got dead silent chain.

Now, I tried iDefender3.0 External USB Ground Loop Eliminator ($50.00) with [!] external clean 5v (power bank) power injection which does reduce USB noise by approx. 80% but still leaves noticeable high pitch noise unfiltered... (it does not really matter where iDefender3.0 goes - either between Mac and Audio Interface or between Mac and C.A.B M - exactly same result - presumably you just need to break the usb ground loop here)

That is in idle state. Once you start fiddling with you ProTools/Logic/TorpedoRemote etc. controls - all the GPU/CPU/HDD noise bursts into the recorded signal...

I may try higher quality isolation devices that isolate both power AND data but It's going to be quite expensive solution (read: several hundred $) for the problem that should have been discovered during factory testing and should have been addressed before releasing a product to public in the first place...

What surprises me here is that C.A.B M does not need USB power to operate since it has its own power supply onboard at all times. So the Vbus and Ground of the microUSB connection could have been properly isolated in the schematics of the unit since its only remote control/SW update interface. I'm not quite sure if D- / D+ interferences/noises could be leaking into main signal chain of C.A.B M though.

Bottom line of the problem itself:
I find C.A.B M unsuitable for recording (usb noise) whenever it is connected via USB to the same PC/Mac to where the audio interface is connected.
Oh, yeah, and ground lift on the C.A.B M does not remedy the USB ground loop when lifted. It just creates additional XLR level (unearthed) noise when lifted.
Oh, and it does not matter what recording interface you use - I tested it with Focusrite 2i4 and Presonus Audiobox - exactly the same story.

Now if you could afford two different MACs - one to control C.A.B M and other to run the interface and recording software - there is no ground loop noise...

While I'm 99% sure software updates will not be able to fix USB ground loop issues of C.A.B M, I'm looking for proper workarounds to be able to use TorpedoRemote UI with C.A.B M without having to deal with USB ground loop noise.

One potential workaround for me is to allow TorpedoRemote (Desktop Mac/Pc versions) to control C.A.B M via Bluetooth.
It is an option for IPad, but I don't have one. Iphone app is not out yet (and even when it will be released it will be nowhere near Desktop or IPad versions in terms of usability simply because of IPhone screen size and abundance of C.A.B M controls to fit into it.)

===========
My setup:
Attachment:
File comment: Setup
Screen Shot 2019-06-01 at 6.32.01 PM.png
Screen Shot 2019-06-01 at 6.32.01 PM.png [ 577.38 KiB | Viewed 1666 times ]


There are no special steps to reproduce needed. Just hook C.A.B M either LINE or XLR out to Scarlett input, connect both Scarlett USB and C.A.B M USB to the same MAC;
Run TorpedoRemote software on Mac/PC.

To A/B test simply plug and unplug USB cable running to C.A.B M while listening trough direct monitoring on Scarlett or actually recording in your favorite recording software.

For the purity of experiment it does not matter whether or not something is plugged into C.A.B M input.
The issue is 100% reproducible w/o anything being plugged into C.A.B M input at all.
==============

So my questions to Two Notes engineers are:

1. Why TorpedoRemote (Desktop Mac) is not allowed to control C.A.B M via Bluetooth in the first place?
C.A.B M bluetooth is not even discoverable neither on iPhone nor Mac.

2. Are there any plans to add bluetooth control of C.A.B M to TorpedoRemote at least to remedy USB noise issue device has?

Will be waiting for you replies.


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PostPosted: Mon, Jun 03, 2019 2:58am 
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Plank Cranker Wanker
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Hi Supahfly,

it's a weird issue indeed. Of course we try with all our computers here and probably 10 different soundcards (most of them USB) and didn't encounter that issue.

Did anyone else here had a similar problem? That's the first report we get.

As a matter of fact, the USB power coming from your computer is NOT connected to the CAB M, we just use the DATA line and the ground. Are you using a laptop with no grounding by any chance? Do you use a separate PSU for your soundcards or are they bus powered?

Quote:
So my questions to Two Notes engineers are:

1. Why TorpedoRemote (Desktop Mac) is not allowed to control C.A.B M via Bluetooth in the first place?
C.A.B M bluetooth is not even discoverable neither on iPhone nor Mac.

2. Are there any plans to add bluetooth control of C.A.B M to TorpedoRemote at least to remedy USB noise issue device has?


The reason is simple: Bluetooth is a great control interface, but a TERRIBLE data transmission interface. The rates are so low that I decided not to provide that option so the user don't feel so frustrated with Remote.

But you are not the first to ask so we may offer that in the future, remember that you'll have to wait for cabinet or IR uploading. ;)

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PostPosted: Mon, Jun 03, 2019 10:01am 
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Hack

Joined: Sat, Jun 01, 2019 3:57pm
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Hi guillaume_pille,

Thank you for your quick response!

Quote:
Are you using a laptop with no grounding by any chance?

The MacBook Pro (2014) in question is using three-pronged AC cord which is supposed to provide ground through magSafe according to apple
https://support.apple.com/en-us/HT203207

Quote:
Do you use a separate PSU for your soundcards or are they bus powered?

Unfortunately both of the interfaces I have at the moment are bus powered w/o even an option for separate power source. (Focusrite Scarlett 2i4, and old Presonus Audiobox vsl 22)

Quote:
Bluetooth is a great control interface, but a TERRIBLE data transmission interface. The rates are so low that I decided not to provide that option so the user don't feel so frustrated with Remote.

I personally don't mind limiting BT operation mode to only CONTROL whatever is already on the unit.

My primary use for it is just to change the settings of C.A.B. M -
primarily - switching from cab to cab (already stored in unit memory) - like for guitar and bass and making minor tweaks in miking and reverb.

I don't mind USB-only connection to upload IRs or new Cabs into the unit as well as trying various cabs available in Store etc.
All these use cases are preliminary tone research steps. Something that never actually happens during a recording session - you already work with the cabs you know you like.

But switching from guitar preset to totally different bass preset including fine tuning of reverb and mics in between the takes happens quite a lot to me right in the middle of recording session.

And for now it is the following routine:
1. Plug USB to C.A.B M - select cab/ adjust tone
2. Unplug USB to C.A.B M
3. Record.
4. Switch to guitar.
5. Plug USB to C.A.B M - select cab/ adjust tone
6 Unplug USB to C.A.B M
7 Record.

And so on. Because of the USB noise.

I still have high hopes for full ADuM4160 based USB isolator that is to arrive in a few days. Will let ya'll know the outcome.


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PostPosted: Sun, Jun 09, 2019 1:14pm 
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Hack

Joined: Sat, Jun 01, 2019 3:57pm
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Ok, here is my update.

I finally managed to solve USB noise problem (presumably USB ground loop issue).

First I tried iDefender3.0 External USB Ground Loop Eliminator ($50.00) with clean 5v power injection which greatly improved audible noise but did not eliminate it.
Attachment:
Screen Shot 2019-06-09 at 1.59.37 PM.png
Screen Shot 2019-06-09 at 1.59.37 PM.png [ 575.68 KiB | Viewed 1139 times ]

==> Did not work for me.

What really solved my issue was this: USB Isolator ADuM4160 Inside up to 5000V DC Isolation and Protection ($38.00)
Attachment:
Screen Shot 2019-06-09 at 1.59.53 PM.png
Screen Shot 2019-06-09 at 1.59.53 PM.png [ 1.98 MiB | Viewed 1139 times ]

https://www.usbgear.com/USBG-M4160.html

According to spec this isolator is not suitable for modern recording interfaces due to lowered speed rates. (Although I tried to put it between interface and Mac and there were no apparent issues.)
But in my case I simply needed to break USB ground loop. Thus I keep it between C.A.B M and MAC.
This little device totally eliminated all audible noises I had with C.A.B M connected to the same MAC to where recording interface was connected.

Now, I had couple weird issues with it: for some reason this USB isolator does not like microUSB->USB cable that is included with C.A.B M. - it was disconnecting and re-connecting sporadically... I took another cable (from my PS4) and FINALLY - no issues. Stable connection. No noise.

Problem solved. Case closed.


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PostPosted: Sun, Jun 09, 2019 3:37pm 
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Hack

Joined: Sat, Oct 13, 2018 10:55am
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Out of curiosity: could it be the USB cable that was faulty all along? Did you try with PS4 cable but without the USB isolator?


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PostPosted: Sun, Jun 09, 2019 4:34pm 
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Hack

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No, when C.A.B M is connected with a different cable (that from PS4) w/o isolator it still has exactly the same noise.
It is ADuM4160 isolator that does the trick.


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