Members daysofspeed Posted March 10, 2011 Members Share Posted March 10, 2011 Interesting article on phase inverters that was posted on another forum. Ive read it before but kind of forgotten about it. Thoguth id pass it on here: Here's the article. "The most important tube in your amp? The Phase inverter! Many people think that V1 (the first gain stage) is the most important tube in an amp. This is true in some cases but not in all cases. V1 (usually the preamp tube closest to the input jack) has the largest impact on your tone and gain but has less impact on your output distortion touch dynamics and output stage distortion than the phase inverter. The phase inverter is generally the preamp tube that is the most close to your output tubes in most amps. Let Link to comment Share on other sites More sharing options...
Members daysofspeed Posted March 10, 2011 Author Members Share Posted March 10, 2011 Continued: There are a lot of great NOS tubes. They have advantages in the tone and gain stage but they are not as available as production tubes made today. When you are on the road or on tour these are harder to find. In the case of the phase inverter we do not want to stock a bunch of Mullards or Telefunkens to burn up every output tube set change. There are great current production tubes that give us all we can ask for. Other great phase inverters to consider are the 5751, 12AY7, and 12AU7. The bottom line here is simple. The phase inverter is one of the most important tubes in your amp and the hardest worked tube in the preamp section of your amp. It is how this tube breaks down that provides your output stage distortion tone, character, and amp feel." Myles S. Rose www.guitaramplifierblueprinting.com Also posted by someone called eugenedunn Although all the common 9-pin twin triodes: 12AX7, 5751, 12AT7, 12AY7, 12AU7 are interchangeable electronically, the 12AT7 and 12AU7 are designed as driver tubes....that is, they have the high current handling capacity that Myles Rose stated.....That is what makes them ideally suited to be Reverb Drivers and Phase Inverters. The other tubes are primarily considered signal tubes so are more ideally suited for preamp and those types of uses. They also have the internal impedance and transconductance that make them best for handling low level preamp signals. I think you have to consider in total, what your particular amps circuitry was designed for when rolling tubes in & out. If your phase inverter circuit specifies a 12AX7, then by all means, swap away..... But if your phase inverter specifies a 12AT7, then it's likely the circuit was designed for the higher current capability of that specific tube type......SO EXCEPT FOR A 12AU7, ALL OTHER TWIN TRIODES MIGHT HAVE A SLIGHTLY DECREASED LIFESPAN IN THAT POSITION, because they're being subjected to higher currents than they'd normally encounter in signal circuit positions....... Interesting......... Link to comment Share on other sites More sharing options...
Members ambient Posted March 10, 2011 Members Share Posted March 10, 2011 Man what a horribly written article. TL;DR, phase inverter tubes matter to your tone. Swapping tubes will sound different. So what exactly does a phase inverter do? Invert phase I'd expect, but what for and why? Is he saying that output tube distortion is actually just the phase inverter distorting not the el34/el84/6l6/kt88s overdriving? Really? Link to comment Share on other sites More sharing options...
Members Yarmo Posted March 10, 2011 Members Share Posted March 10, 2011 I would trust Myles. Super guy and very helpful. Link to comment Share on other sites More sharing options...
Members ambient Posted March 10, 2011 Members Share Posted March 10, 2011 I would trust Myles.Super guy and very helpful. Probably right. But didn't explain much and for an article on phase inverters, he talked about them very little. Link to comment Share on other sites More sharing options...
Members spentron Posted March 10, 2011 Members Share Posted March 10, 2011 This doesn't make sense:In real life we rarely get to the point of pushing our output tubes to their limits. Our front end is going into distortion. Our phase inverter is breaking down too. Distorting the phase inverter (substantially) occurs at a higher level than output tube distortion. If you're not pushing the output tubes somewhat hard -- to the limits of what the phase inverter will drive them -- you're not pushing the inverter. This is about as basic as gets.It is true perhaps, it is an ignored and important tube in many amps. The stuff about "Channel switching amps. Many of these amps have so much Link to comment Share on other sites More sharing options...
Members smgbad Posted May 10, 2011 Members Share Posted May 10, 2011 Very useful and educational post. Thanks for putting it up. Link to comment Share on other sites More sharing options...
Members Dr.Picklebottom Posted May 10, 2011 Members Share Posted May 10, 2011 yep, good stuff. Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted May 10, 2011 Share Posted May 10, 2011 I would trust Myles. Super guy and very helpful. As would I. I have a great deal of respect for Myles. He definitely knows his stuff. Link to comment Share on other sites More sharing options...
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