Download crossover distortion

The Last Word On BiasingGeneralThere are only two things to worry about in biasing a guitar amp. The first and foremost is not to set the bias current so high as to exceed plate dissipation at any portion of the tubes operation, as indicated by that nice warm red glow of melting plates and the sound of a cash register ringing up a new set of tubes. The second is to not set the bias current so low as to sound bad, which generally means approaching or exceeding class B operation as indicated by the onset of heavy crossover distortion. Any point in between these two is fair game and is subject to personal taste. There is no single "correct" bias point.Biasing methodsThe negative grid voltage method: This method involves measuring the DC voltage on the grid of the output tubes, and setting it to a recommended value. Biasing by negative grid voltage is highly inaccurate because the same grid voltage can produce drastically different plate currents in different tubes of the same type. This method should be avoided.The crossover distortion method: Biasing by the crossover distortion method as indicated in the Pittman book and other literature is also extremely inaccurate because the point at which crossover distortion appears is very hard to detect and is subject to changes with load impedance, amount of negative feedback, and, in particular, with grid drive if the phase inverter is AC coupled to the output tube grids (as it is in almost all guitar amps). Following are additional reasons why this method should be avoided:When driven into the positive grid region at clipping, the output tube grid acts as a forward biased diode and clamps the positive peaks of the grid waveform to a point slightly above the cathode voltage. As the input signal level is increased, the clamping action forces the average value of the grid waveform downward, effectively increasing the average negative grid bias. This results in more crossover distortion, even if the amp is biased higher into class AB. Because of this clamping effect, the amount of crossover distortion that you are trying to "bias out" will change depending upon how far into clipping you set the grid drive. If you keep trying to eliminate the "notch", you will bias the amplifier too hot, and your tubes will be destroyed.This method gives no indication of the actual bias current or plate dissipation in the tubes, so you have no idea whether or not your amp is biased into a safe region of operation. If you have two class AB amplifiers, one with a plate voltage of 350V, the other with a plate voltage of 550V, and set them both using this method, the amplifier with the 350V plate voltage may be biased too cold, while the amp with the 550V plate voltage may be biased too hot. If you try to bias a push-pull class A amplifier using this method, you will end up biased right to the cold side

Passive crossover, a source of audible distortion of your sound, with a precise Active Crossover placed ahead of your power amps. The power amplifiers drive the woofer and tweeter directly with no passive components getting in the way. The result is nothing short of breathtaking. You’ll hear detail and color in your music you’ve never heard before. The sound stage opens wide in all dimensions, and you can picture every instrument as if it was in the room with you.One of the most important specs for an active crossover is phase coherence. This is the alignment in time of the high and low outputs. If these are out of phase, sounds that are at or near the crossover frequency will be significantly distorted, because both the woofer and tweeter are both driving at this frequency, and if the channels are out of phase they will each be creating slightly different sound, which creates distortion. This video shows how precisely our channel phases are aligned:

Came stock with these same GT6L6B's. I was able to register this morning to join the forum and can finally talk with someone with my same question. I just learned about biasing from Justins site awhile back and being new to tube amps just wanted to see where my '05 HRDx was biased to begin with. Turns out mine was at 77mv. My concern was that based on what I had read on Justins site about how a "cold bias" would sound, I thought mine might be low because Im hearing what seems to be crossover distortion...a sort of underlying rattle type sound on clean single low notes that dies out before the note itself does. But at 77mv I suspect maybe its not crossover distortion after all? 04-26-2008, 02:19 PM #23 Forum Member Re: Biassing GrooveTube 6L6B Originally Posted by dant But at 77mv I suspect maybe its not crossover distortion after all? Again, this number means nothing without the plate voltage. The mV measurement is half of the equation when figuring the percentage of max plate dissipation.For example, at 69% max plate dissipation, my mV reading is around 110mV. That's on a stock HRDlx power transformer.JLD, if you were to buy a 1/4" plug new and not wire anything to it, you'd have an open plug. It's basically forcing open the jack inside the amp.If you have an 8ohm speaker load running on the 4ohm tap, and the OT primary is 4K, you can use 6V6s. The HRD

Way they are. Set the switch to Lo, and hear how you now only get boom from the toms, but the room sound and cymbals stay unaffected.More than percussionThe dual band operation makes Transient Shaper useful for much more than drum and percussion sounds. Give a vocal track clarity and presence by adding some high frequency transients — add Punch with its frequency slider set to Hi. Or create a darker and more rounded sound that oozes with vintage vibe by instead turning down the Punch knob. Use it on piano, bass, guitar, electronic drums — Transient Shaper works on a wide range of sound types.The crossover frequency is user selectable, as is the Punch behavior (Fast or Slow). We also added an output distortion section called Clip.In shortDual band transient processing tool.Add or reduce punch and/or sustain from any sound.Affect either the whole frequency spectrum, only the high frequencies or only the low frequencies.User selectable crossover frequency.Clip section adds output distortion.

Faster heat dissipation. Drivers Magico Nano-Tec drivers exercise absolute control over voice coil movement by providing underhung voice coils in a magnetic circuit of tremendous power. Uncommonly large Neodymium ring magnets with 16 times the magnetic energy per unit volume of Ferrite form the motor system. An extra measure against asymmetry, the drivers deploy a matching magnet on top which enables distortion-free output up to 120 dB SPL at 1 meter. The new 6-inch midrange (x1) features a 3-inch voice coil to help maintain linear output all the way to 120 dB SPL at 1 meter. This results in unmeasurably low distortion throughout the driver’s operating range. The new 11-inch mid bass driver (x2) features a 4-inch voice coil with a N48H grade Neodymium ring magnet of unusual size: 120 mm diameter x 8 mm height, plus a second matching magnet on top for complete control of voice coil movement. The new 15-inch bass driver (x2) features a 5-inch voice coil with an uncommonly long 36 mm air gap that facilitates tremendous linear excursion, ±15 mm, at high sensitivity. The M9 drivers represent true state of the art and are the most advanced dynamic driver designs ever offered by Magico. Crossover The new Magico Analog Crossover (MXO) was designed in-house from our own platform to manage the crossover frequency between the 15-inch bass and 11-inch mid-bass drivers. At such a low frequency, a passive crossover would require huge inductors and capacitors which would incur substantial losses. The meticulous design of the MXO has fully balanced and discrete circuit topology with Linkwitz-Riley filters to deliver steep 24 dB per octave slopes at the crossover frequency of 120 Hz. Precision step attenuators provide 0.5 dB/step control of each output, using a proprietary technique to ensure purity in the signal path. Open architecture