Good to know that tubes do have other intrinsic distortion properties that make them sound different from transistors apart from just the high output impedance. Talking of distortion I remember an article in one of the IEEE Spectrum mags that talked about 2nd order distortion of tubes being different from those of transistors. They also had some actual measurement results (no cascading electron theory there) to show that tubes infact have different distortion spectra from transistors. I am looking for the article and will post it in this thread or perhaps in another new thread.
Although this article is geared more towards musician amps I wonder whats John Murphy's opinion about negative feedback used in SS amps for home use, to reduce the distortion and flatten out the FR and if at all it impacts sound. I have no idea about this aspect of amplification so any links on the subject would be greatly appreciated. Do you have John Murphy's e-mail (couldn't find it at the site)?
This is why I luv this hobby. Everyday you learn something new.
Thanks again Chu.
P.S. John's discussion about amplifier damping factor is quite interesting too. I always felt any damping factor over 10 (my tube amp has a DF of 8) is marketing hype and its good to know that John feels the same.
That'd be great Yogi. I know I oversimplified matters some when I focussed primarily upon output impedance and distortion. I had tried to allude to the other matters such as the variability aspect of tubes when I went on with that hypothetical DBT scenario with Mr. Beavers. I think though that I'd mentioned about tube characteristics being modelled in solid state on a pro level. We can see from this article that the guy has done expressly that for Carvin (nice people...nice guitars, nice to see stuff made in the USA too!). I think if we all cast off our subjective interpretation of things, and that includes scientists too, and do careful, probing research, reasonable explanations and a better understanding of matters come out. There's no reason, to my mind, why we have to dumb ourselves down. I like to think that the more useful information and knowledge we possess, the better the decisions that we'll each make for ourselves.
As the author states, they are treasured because of how they distort. Whether or not that can be simulated effectively with solid state electronics, is, in the guitar world, just as controversial as analog vs. digital in the audio geek world.
Sure, lots of kids will automatically go for a tube amp because their favorite guitar gob plays one. Heck, I'm no kid, but I have two, a small bore Fender and a Boogie. And I wouldn't trade 'em for anything. And one day, I am going to have a Marshall stack that is capable of shooting down enemy aircraft...but I digress.
Now, I don't know that I would totally accept the premise that anything that can be done with tubes (in terms of guitar amplification) can be done solid state. Players that are seriously neurotic about tone, guys like Eric Johnson, have nothing at all to gain from continuing to wrestle with vintage tube amps, other than they think they sound better. And take a listen to his tone. Its incredible. Could he do it solid state? While he would still sound like Eric Johnson, I really think something would be missing.
This is a very interesting article, to be sure, but the author makes it sound like the sound one hears on stage is always the sound of the stomp box, simply made louder. In many cases, thats really not true.
While there are many types of stomp boxes (overdrives, distortion, fuzz), what most serious players shoot for is something that will overdrive the input stage of his/her tube amp, thus allowing the output stage to go into clipping at a lower volume. The goal is to get the sound of an overdiven tube amp, at less than stadium filling volumes.
The classic Marshall sound of the sixties (non-Master Volume Plexi's for example) could only be had at full volume. Thats why Pete Townsend is said to be nearly deaf!
The Ibanez Tube Screamer is exactly that kind of pedal. Favored by Stevie Ray Vaughn, among others, its purpose in life was to kick up the signal going into the front of his Fenders, Marshalls, and Dumbles. The sound of the pedal itself is weak and anemic. It exists simply to push the amps over the edge so to speak.
The point is to get the sound of a cranked tube amp, with out having to crank it.
If you want to read some stuff on the subject, check out this link. I really don't think there is much voodoo there...just article after article about guitar amp tone.
Good point David I must have passed that by. I thought the point about duty cycle was interesting but this is even more interesting. Perhaps I should e-mail Mr. Murphy and ask him what in particular he was talking about.
Nice article DJ Now I am really confused. How do you know Mr Hamm didn't have any bais towards tubes? But then how do you know this other author didn't have bais towards transistors? The plot thickens? They both are presenting opposing views. I would, however, trust the JASE article more than the EE times article, being a physicist myself and knowing how hard its to get publications in a journal as opposed to getting it in a newsletter/periodical.
That he did, but according to my copy of "The Marshall Amp", a recent Guitar Player special edition, Pete was actually the reason that they did the first 100 watt head, as well as the 4x12 cab.
Per the article, Pete was always bitching at Jim that his amps were not loud enough. As for the cabs, Pete wanted a 8x12 cab, but his roadies revolted that it was too damn heavy, so Marshall did the next best thing, stacked 4x12 cabs.
There is actually a nice photo of Pete, dated 1966 (Windsor Jazz and Blues Festival) running the head stock of a Tele through the top cab of one of the very 1st Marshall stacks.
But he did eventually switch to Hi-Watts, and was most often associated with that brand.
OK, I will now return this thread to its intended purpose.