amsdenj

I can't think of any reason that an IR in Helix with Powercab in FRFR mode would sound different than the same IR in Powercab. The actual processing should be the same. Where IRs in Powercab are useful is if your modeler doesn't support IRs, doesn't have enough DSP space for the IR in the patch, or you want to save a block in something like HX Stomp. I haven't actually compared them though as I use IRs in Helix out of convenience, use amp+cab models in HX Stomp to save the block, and mostly use Powercab in FRFR mode. I have however used the speaker models in Powercab on occasion and found them pretty useful. They sound different, and different is ok. Sometimes when we're comparing things we spend too much time trying to make them sound the same, thinking one is bad if we can't get them the same. Instead we should celebrate their differences and use them to our advantage.

I can confirm that Helix Native 3.11 works fine for me on macOS 11.4. Logic's plugin manager shows it as validated and does list the version as 3.1.1, but I've seen that representation in other places too. It's likely just a display convention and they're the same thing. I'm guessing that you might need to check your Line6 login in Helix Native.

I too have had trouble with my old Focusrite Saffire Pro 40 interfaces in recent macOS versions. But what I have found is that the simple Firewire to Thunderbolt adapter Apple sells works fine even in Big Sur. I did have trouble getting the Saffire kernel extension to load. But that was because of other old kernel extensions that wouldn't load and needed to be deleted. I cleaned these all up and now its working fine. I have two of them and they are the heart of my studio. Its great that they keep on working. Regarding using Helix as an audio interface vs. something like the Saffire or Scarlett interfaces, it depends a bit on your workflow. I like having everything into Logic Pro X setup the same from project to project so there's no changing audio devices. This allows me to leave a lot of things setup and ready to record vocals, guitar, bass, mandolin, etc. without having to do anything but move mics and pick up instruments. One easy option with Helix floor is to use the SPD/IF output connected to the SPD/IF input on your audio interface if you have one. This allows you to use your audio interface, but go all digital from Helix, avoiding unnecessary conversions.

If you use HX Stomp with a preset containing no blocks as your audio I/O device into Helix Native, then the input/output meters in Helix Native should closely represent the actual input and output to HX Stomp. So if your guitar is pushing HX Stomp too hard, you should see high input levels into Helix Native. Then any patch you create using Helix Native should work the same in HX Stomp. That is, if the input into Helix Native isn't clipping, and after going through all your blocks, the output in Helix Native isn't clipping, then you shouldn't get any clipping with the same patch loaded into HX Stomp.

You can also leave Snapshot Bypass on for a particular block bypass if you run out of stomp switches and want to use a snapshot just to run on an effect. This actually takes two snapshots, one to turn the effect on and another to turn it off. But that’s ok. I use this for my Leslie block as I have already used the 10 stomp switches for other purposes.

Get the stereo out from Helix, not Powercab in this case. But generally stereo isn’t that useful in live gigging situations unless you’re a solo artist.

There have been a few pretty significant and useful updates to Logic Pro X recently, and some of the newer ones require features in the newer macOS. Updating can be a pain. My old MOTU FastTrack Pro MIDI hub no longer works in Big Sur. There's no kernel extension update from MOTU yet for MIDI devices. It's kind of the price of progress. I generally don't mind and prefer to keep things updated.

I have experienced some strange issues with Helix Native 3.10 on macOS Big Sur with Logic Pro X. In one plugin, the setlists were all blank while another plugin in the same project looked correct. Blocks that had bypass assigned to automation switches couldn't be controlled from the Helix Native plugin API. Automation switches were controlling bypass on the wrong blocks or multiple blocks. I was able to resolve all these issues by removing the plugin and adding it back. That indicates there may have been some state saved in the Logic Pro X plugin that became inconsistent with Helix Native. If you have any problems with Helix Native, try removing the plugin and adding it back.

The input 1/2 and returns probably have different impedance.

If you're monitoring through software monitoring in Logic, and you have certain plugins added to the track or the master track, you could be getting a lot of latency through the plugins. Try using Logic's low latency mode and see if that helps.

I just replaced the USB jack in my Apogee GiO. It wasn't that difficult. But I still think I'd prefer to have Line6 repair HX Stomp because of how compact it is.

Helix guitar input seems to have been designed to handle a typical double coil pickup played pretty hard. You can test this by using a Helix patch with no blocks and the output level set to 0dB. You'll see that the guitar played hard will push the output pretty close to 0dB. If you put a pedal between your guitar and Helix input, and crank that pedal level up well above the guitar level, you're going to clip the input and that's not going to sound good. However the same is not true for the same pedal block in Helix. Once you're into the digital domain, you can push the level of a distortion block pretty much any way you want and not worry about digital clipping as long as the total output stays under 0dB.

Maybe consider a Pod Go for this application - it has mostly the same effects and amp models but is much simpler. The other way around complexity is to provide a bunch of starter patches for typical Fender, Vox and Marshall amp setups. HX Stomp has the power, but with limited knobs, switches and blocks, it requires a lot more knowledge to use effectively.

@sounddog, the video you referenced does indeed work. But it has a few problems as I noted in the 2nd to last paragraph in the original approach. Controller assignments in Logic Pro aren't localized to the project - they are essentially user preferences that apply to all projects. So what works for one track in one project might not be appropriate for another track or another project. This is both a limitation and feature of Logic Pro depending on your perspective. Its a limitation if you want to use MIDI controllers for very different things in different projects. Its a feature if you want your MIDI controller to work the same way in all projects. You can do most anything you might want by editing the Logic Pro MIDI Environment, but it isn't easy. The second problem is that the when recording the audio track with parameter automation controlled by a controller assignment, often the automation parameter is not properly initialized at the start of the track. The automated parameter may pickup the value from the first MIDI message it receives and apply this change way back to the beginning of the track - usually not what you want. And of course there are the limits of 16 knobs and switches for parameter automation. As I pointed out above, there are ways to work around this, but it tends to be a bit complicated and unreliable.

You might also consider a Variax if pitch shifting is something you want to do a lot. Variax has a separate pickup for each string, so the pitch shift algorithm doesn’t have to detect the individual notes from the played chord. Also limit the effects you have going into the poly capo. The less complex the tone the easier it is for the algorithm to detect the individual notes. Keep the input into poly effects close to the dry guitar and put the effects after the poly block.