amsdenj

I have indeed read https://robrobinette.com/Tube_Guitar_Amp_Overdrive.htm many times.

It occurs to me that a lot of readers of this forum might not know what bias actually is and why they should care. Changing the Bias and Bias X controls on a Helix amp block might not do that much to the tone, depending on how hard the amp is pushed. Understanding what bias is might help you understand what these controls do. Here's a brief description of bias that might provide a context for understanding what it does in Helix. Tubes amplify by heating up a cathode that boils off free electrons. These electrons pass through a grid and are attracted to a positive plate, creating a current in the tube. A small change in voltage on the grid can effect a much larger change in voltage on the plate which is an amplifier. Now imagine an alternating input voltage on the grid. On the negative half of the input voltage, electrons will be repelled by the grid back to the cathode, reducing the current through the tube. On the positive half of the input voltage, electrons will be accelerated past the grid to the plate, increasing the current through the tube. This is how a tube amplifies an input signal. Now a tube has operating limits based on how it is designed - how hot the cathode can get, how big the plate is, how far away from the cathode it is, etc. If you keep increasing the negative voltage on the grid, eventually the electron flow will stop, and at that point increasing the input further results in no corresponding further decrease in the output. This is called cutoff. Its very sharp, and results in a lot of odd order harmonics. If you increase the positive voltage on the grid, it will attempt to push electrons faster and faster to the plate. But eventually the plate won't be able to consume any more of the electrons and the output won't continue to increase with the input. This is called saturation. Saturation distortion is more gradual, less sharp and generates even order harmonics. Bias is a voltage difference between the cathode and grid that establishes the operating point of the tube between saturation and cutoff. Normal bias sets the voltage so that the tube is operating over its linear region. Hot bias reduces the bias voltage, allowing more current to pass through the tube when there is no input - the quiescent current. This makes the tube tend to saturate earlier. Colder bias increases the bias voltage allowing less current to pass through the tube when there is no input, giving the tube more headroom, but increasing the chance that it will reach cutoff.

To avoid gain buildup, and any potential for digital clipping, I generally make sure any block I add is "unity gain". That means I set the level of the block so the overall level doesn't change much with the block on or off. This also helps level your patches, and ensures that each block is getting an input in its sweet spot - the input level it was designed to accept. Hopefully the 2.9 level meters will help with this. But you can use your ears to get pretty close, or a level meeter in your computer, or even a dB meter in your phone.

Best to provide a max and consistent signal to Powercab, and adjust the overall volume at the Powercab. That is, push tone, pull volume: use drive and master volume controls to set the amount and type of distortion, use channel volume to provide block unity gain and normalize levels across patches, run Helix into Powercab at full volume, and control the overall volume at the very end of the signal chain using Powercab volume. To achieve a boost, its best set the normal output at -3dB, and when you turn on the boost, set the output to 0dB. This ensures a boost will never drive anything downstream into clipping. General rule is to cut what you don't want rather than boost what you do want to preserve headroom.

You can use a rag slipped under the knob, wrapped around and pull up. Its safer than prying which can damage the pick guard.

I can't answer the detailed technical questions but can maybe provide some useful guidelines. Biased hot: Stronger overall output, more lows, not as much clean headroom, more saturation and less cutoff distortion, more even order harmonics, tubes wear out faster. Biased cold: Weaker, thin, harsh output, Lows aren't as strong, more clean headroom overall, more cutoff and less saturation distortion, more odd-order harmonics, and the tubes don't breakup as fast. I don't know what the range of the Bias control is, but I would expect 5 to be where the tubes are normally biassed, 0 is colder, 10 is hotter - but how hot/cold is unknown. The above applies to typical Fender, Vox and Marshall amps where the majority of the distortion is coming from the power tubes, and where negative feedback is lost (because the power tubes are clipping and have no more gain), and therefore damping factor be lower. For modern high gain amps where most to the distortion is coming from the preamp section, power tube bias can have a very different impact. A slightly colder bias might tighten up the amp, and improve the transient response. Hotter bias might result in less controlled tone and too much muddy bass. So biasing hotter for blues in small amps and biasing colder for metal in high-gain amps might be something to try. Bias excursion is caused by distorting power tubes causing increased grid current which charges the coupling capacitor between the phase inverter and power tube, which changes the bias of the power tubes. When the input stops, the coupling capacitor slowly discharges allowing the power tube bias to recover. This could make an amp that is biased hotter, become colder biased as it is pushed further into distortion, changing the color of the distortion. Maybe when the hotter biased power tubes are pushed to the edge of breakup there might be warmer even order harmonics, and better bass. As the tube is pushed harder the bias gets colder, there might be more odd order harmonics for more aggressive sounding distortion, and the bass might be reduced.

Glad you’re having success. The Powercab will do a pretty good job emulating a 1x12 closed back cabinet with the different speaker models. Use low cut to emulate the bass cut of an open back cabinet. This won’t fill the room the same way though as the reflections are different. But don’t expect to use a 4x12 stack cab model or IR in Helix and expect it to sound and feel like a 4x12. It might sound good, but will be different.

I have both because I really wanted stereo for long term use. The 212 is a lot heavier as you might expect and bigger, taking up a larger footprint on the stage. I play in a lot of small clubs, so stage space is a premium. I often have to turn the 212 on its side and/or stack it on top of the bass amp to minimize floor space. There’s more punch from the 212 because it has more power and more speaker surface area to move air. It sounds wonderful in the studio, but they’re not that different in a live situation since I’m using IEM’s in stereo anyway. Now the band is trying to go amp-less as much as possible to reduce setup and teardown time/work, reduce stage volume, and get better control of the FOH mix. So last few gigs I haven’t used either the 112+ or 212. I’d say if you’re use to a 1x12 traditional guitar amp, the 112+ is fine. If you’re doing a lot of ambience patches in close with your audience, then a 212 might be better.

Try turning off the IR in your modeler and use the speaker models in PowerCab. You might find that sounds more natural.

I think there may have been a problem with the USB connectors on some HX Stomps - mine broke within days and never left the house. I found the black plastic piece on the floor and glued it back in. Seems to be working fine for some time now. But I should get it repaired.

On MacOS Catalina, Helix Native(AU64) shows up in the Minishost Modular plugins list, but attempting to add the plugin doesn't do anything. Other AU64 plugins work, just not Helix Native.

That’s one way to look at it. In the absence of any other evidence, this is a good approach. Another explanation might be that evolution has two sides, a push and a pull, or a challenges and opportunities. These can create a feedback loop where one contributes to the other, accelerating the process - like guitar feedback. For humans, it might have been the evolution provided an opportunity through our upright posture and hands allowing us to farm, producing more food than we needed for our own survival. This abundance of food might have allowed the development of the human brain, which requires a lot of fuel. Organisms trend to be as smart as they can fuel their hungry brains. This excess wealth may have opened an opportunity for tribes, societies, religions, governments, etc. to exist which in turn provide an environment that supports raising our expensive young, with their primitive, but highly adaptable brains. Or it could have been the size of the whites of our eyes allowed us to communicate visually (you can tell where someone else is looking) and that give us an edge through cooperative hunting. Or... The world is a rich place to explore. Anyway, interesting discussion to keep us distracted. Note however, that this process of evolution rooted in challenge/opportunity apples pretty well to Helix upgrades!

A good set of studio monitors will reproduce Helix well in an appropriately sized room. And they can be used for lots of other things. I wouldn’t use a Powercab 212 as a studio monitor though. Although its a FRFR, any FRFR is optimized for a set of usage scenarios, and Powercab is optimized for guitar. I wouldn’t hesitate to use it for a keyboard amp, or for solo acoustic gigs. But I’d probably never use it for a stereo speaker or mixing.

Maybe this is overly simplistic, but it seems to me faith is the belief that what you know now will help you survive the chaotic uncertainty of the future. That's it's source of peace. I don't have a problem with that, what else can we do after all? However, I think its important to subject faith to constant scrutiny, that's how we learn, adapt, and improve our chances of survival. Exposure to diversity is a great way to accelerate learning. However, faith can also have another dimension, that of tribal identity ensuring access to shared resources and a common gene pool, another means of increasing the chances of survival. These two dimensions, and perhaps others can sometimes collide. 2.9 had better get here soon or we're going to start going off the rails!

I have not personally used my HX Stomp for gigging - it was intended as my backup and portable rig for rehearsals. However, the band has decided to go ampless the last few gigs to try to get better control of our stage volume and reduce our footprint. Just when I just got my Powercab 212 too! Anyway, the other guitar player in the band, and our bass player are both using HX Stomp the last three gigs. Its working great. I'd suggest not worrying too much about a lot of patch switching with HX Stomp. Keep things minimal. I created a patch for him that has three stop switches: distortion, phaser, chorus, delay and reverb are on all the time. This is all he needs for 95% of the songs. And it keeps it simple enough that the HX Stomp doesn't become a distraction.

Everything is empty from its own side. Things are how we perceive them and that is our unique experience of life. Best enjoyed because it is temporal in order to make room for other life. It is its own meaning, a tautology. Making it complicated is almost always to someone else's benefit. Interesting conversation, and a nice way to find distraction while waiting for 2.9.

Think of it as three levels of control: presets for individual songs, snapshots for specific sections within a song and stomp footswitches for controlling effects in a song section. Presets have the advantage that they can have completely different signal paths, blocks and parameters, as well as a set of snapshots. They have the disadvantage of having to maintain a lot of them, a brief pause in sound while the preset loads (so switch them between songs) and no ability to have reverb or delay tails across presets. Snapshots have the advantage of being able to instantly change up to 64 parameters in a patch with a single footswitch, no pause in sound and reverb and delay tails are preserved. Snapshots have the disadvantage of not being able to combine things from two different snapshots live (you can't have two snapshots on at the same time), and you can't change the signal path or blocks. Stomp footswitches have the advantage that you can as many as 8 things (bypass, parameter min/max values) on a single footswitch and any combination of up to 10 switches - controlling the stacking of effects - within a single patch or snapshot. This gives a tremendous amount of flexibility and combinations of tones on 10 switches, just like a traditional pedalboard. Use presets if you like to create a different sound for each song. Use snapshots if you like to control your tones in different sections of a song. Use stomp footswitches if you have your own sound, and want complete control of the combination of effects you want on at any time, for any song, or any section of a song. I pretty much use one preset for a whole gig. I have a few presets that are song specific because they require something odd that wouldn't be in by typical setup. I use snapshots in my goto preset for changing variax open tunings. And I use a combination of Helix and HX Effects together to give me the footswitches I need to control the effects I use most of the time. The beauty of Helix is that all these different operational setups are easily supported, allowing each of us to optimize our setup for our individual needs.

Maybe it's a matter of realistic expectations. Do the Variax models sound as good as their real counterparts? No, they don't. And there's some variability in different guitars that result from variability in the piezo pickups, how well the neck is attached to the body, quality of the setup, etc. So I'd never claim that I love to listen to the Variax models when playing by myself while practicing. Nor would I be too motivated to record with them. But gigging in a live band situation - nothing beats Variax, nothing. The flexibility of the models, tunings and MIDI control is just fantastic. And in that context, with a full band, playing in anger for an audience, I really doubt if anyone could tell the difference between a Variax model and the real thing. If you're Matt Schofield, you're not going to use a Variax. But if you're playing in club bands semi professionally, you can't beat a Variax. I have a 60 year old Les Paul, a very nice Strat Deluxe, a Tele and a Epi Sheraton Pro - all really fantastic guitars. For gigging, I always bring my JTV-69S as my main guitar, and rotate the others just because I love them and want to play them. The JTV really does all I need for gigs and always gets the most playing time. But that Tele... It's new to me, and I'm really loving it. That Tele quack really seems to speak to me. I haven't gigged with it yet, but will soon. I get that its always the new guitar that gets the attention. But this feels different to me.

What would work is block links instead of copy. In a patch, you would add a link to a block in another patch, not a copy. Then any changes to the target block would be see in all the blocks that like to it automatically. Helix doesn't support block links yet. Hopefully it will someday. In the absence of that, you have to redo the copy paste to propagate changes. That's a pain, but not that difficult with Helix Native and HX Edit open at the same time.

Rumor has it that 2.9 HX Stomp will have 8 blocks! This will really increase the utility of HX Stomp for me and make it a more viable option or backup for gigging. 8 blocks will allow me to add an always on compressor and Wah to my existing patches. Very wonderful news.

My HX Stomp got stomped on at rehearsal the other night and the top encoder knob shaft got bent. This caused the encoder to turn hard. I just bent it back with no problem, at least so far. It appears that these encoders are well attached to the chassis and can stand to be stepped on and bent a few times. I don't recommend it of course, but was happy that HX Stomp could withstand this potentially common issue.

You could also create template patches and "global block" sets in Helix Native, and use these with simple copy/paste to Helix, HX Effects and/or HX Stomp patches using HX Edit. This is just another way of saving the block parameters.

Excellent analysis. @codamedia, your contributions are always great, thanks. One more consideration might be pickup height. If all the guitars are setup the same, its possible pickup height is the issue. Try lowering the pickups to improve responsiveness and tone.

Testing a lot of IRs can be very tedious and unrewarding. A lot of them will sound pretty similar and you can go nuts trying to figure out which one you like best. What you need is some way of filtering things down to smaller sets of things that have discernible differences. Start with thinking about the tone you want based on your experience, preferences, song styles, type of guitar, preferred pickup, etc. All tone starts with the source. Then see what other players whose tone you like are using. Watch live concerts and see what mic they are using and where its placed. Next pick the kind of speaker you want, one that is generally known to be able to produce the kinds of tones you want. This can take some research to read about different speakers and how they sound, as well as look up speaker comparisons, especially those with audio so you can get familiar with how different speakers sound. Next pick the kind of mic you want based on what you're trying to get out of the speaker. If its loud rock, an SM-57 will work fine. If you want something warmer, go with an R121 or some other ribbon mic. If its clean jazz, probably any condenser mic will work. All the mics will sound different, even mics of the same type (dynamic, condenser, ribbon). But these three will have the biggest differences and will help zero in on what you're looking for. Finally consider mic placement. This has a big impact on tone and can give a lot of different tones even with the same speaker and mic. Closer mic'd will have more boomy low end because of proximity effect. Closer to the center will be brighter. Start with 1" and cap-edge and move from there. This approach should narrow down 1000s of IRs to 10 or so. Load these up and play through them at gig level. Pick one and stick with it for a while. Playing is much more fun that worrying about the perfect IR you might be missing.

I add an IR or Cab block to the patch. If I have a patch that uses the powercab speaker models, I bypass the IR or Cab block. If I need to go directly to the PA (no Powercab), I turn the IR or Cab block on. I don't like copying patches because its too hard to keep them all updated. I wish Helix allowed block links to blocks shared across patches.