Ilya-V

Make sure you set the 1/4" Outputs to 'Instrument', you'll have much better noise floor. The big volume control is digital and before the DACs, so don't be shy to turn it up because it doesn't add noise.

Thank you amsdenj, many people will be reading this thread with more accurate explanations than could be found before. Here is a link with what I think the best technical explanation of Bias Excursion, Grid Clipping, Blocking Distortion on the internet. https://robrobinette.com/Tube_Guitar_Amp_Overdrive.htm

I got my Helix this morning and I started the update procedure and the exact same thing happened,, "Boot Failure. Entered Update Mode!" and Line 6 Updater showed nothing,, my Helix was not detected in the Updater,,, even though it WAS detected when I started the update procedure to v2.82. I restarted the Helix and my PC several time to no avail. This was really nerve wracking, I thought I bricked my Helix without hearing how it sounds. The solution was change the USB port from the front of my PC to the back, and restart Line 6 Updater,, then it appeared and I continued the update normally. The strange thing is I started the update from the front USB ports.. but they stopped working in the middle of the update WTF~! The front USB ports working perfectly fine with everything I used them for up till now. Line 6 should really stress the importance of using the back USB ports of the PC while updating,, or fix their Updater software which definitely broken in that regard.

I've seen that video, but I'm looking for a more technical description of what the parameters change in terms of the emulated components. I've measured my amp (into a dummy load) with an oscilloscope and I can clearly see the same crossover distortion and bias excursion behavior in the Helix emulated amps as in the real amp. With sag control at maximum I can hear additional distortion besides the obvious volume drop, probably from the voltage drop on the anodes of the 12ax7's. Truly remarkable that Line 6 actually emulated that. Sag also behaves differently between amps and I can hear the speed of voltage drop differs between amps, so maybe it's not a series resistor but a fully emulated resistance+inductance of the secondary windings? On the spectrum analyzer I can see that Hum and Ripple behave harmonically (even harmonics of 60Hz) like an under-filtered (low capacitance) rectifier bridge. Again, I am amazed that it is emulated that accurately here. There is no doubt that the Helix simulation is component based, but the advanced amp parameters need to be clearly explained for they tech savvy folk too. I am interested to know what Bias, Bias-X, and Sag do component and voltage wise in the emulation, since they behave remarkably similar to a real tube amp I've measured.

Hi, first post. I would like to know what Bias and Bias X controls do in terms of component emulation, beyond the general 'feel' descriptions I can already find. I will elaborate the questions further; BIAS: My question is whether this control changes the cathode resistance and changes the negative voltage on the grid of the power tube? If so, what range does this control have in terms of effective bias idle wattage? ie; If the emulated tube wattage is 30W (6L6 for that matter),, does changing BIAS between 0 to 10 changes the idle current from 0W to 30W at idle (full class B to full Class A)? So BIAS value of 6-7 where most emulated class AB amps are set will result in 60%-70% of Tube wattage at idle, like real tube amps biased at? BIAS X: (Excursion I assume?) If that indeed excursion, my question is what component does this control emulate exactly? Does this change the voltage swing of the phase inverter, maybe the coupling capacitors size, or grid resistors size? https://www.ampbooks.com/mobile/amplifier-calculators/bias-excursion/ SAG Does this emulate the HV++, HV+ voltage drop with a resistors in series with the power supply when a large current is drawn? In a tube amp the secondary winding of the power transformer has significant resistance, so when the amp draws current, all the anode voltages of the amp drop or 'sag'. I've bought a Helix recently and these controls imo are very important part of the power amp emulation. I would appreciate the Helix much more if I actually knew what these controls do in terms of component emulation. I've also built and modded a few tube amps, hence the technical questions. Thank you.