I do get the difference between even ordered harmonics for tube gear being preferred over the odd-ordered harmonics for solid state for sound quality itself. But 2-3% vs say 0.06%?

Here's one I found:

Antique Sound Lab MG-SI15DT Integrated Tube Amplifier - Single Ended, Pure Class A Operation

Rated Power: 5 Watts RMS Per Channel into 8 Ohms in Triode Mode, 15 Watts RMS Per Channel in Tetrode Mode

THD: < 2.5% at 5 Watts, S/N: 78 dB, MFR: 17 Hz - 28 kHz ±1 dB at Full Output, Size: 7 3/4" H x 19" W x 18 1/4" D, Weight: 25 Pounds, MSRP: $699 USA

An admittedly "entry level" tube component, for $700...

Another, more premium one:

http://www.stereophile.com/showarchives.cgi?687:6

See Fig. 3.

Again, Kevin, what power level, what kind of tube amp - class "A", "A/B"? I mention this because tube amps have extremely different distortion behavior than solid state ones. Since the 'knee' is so broad at the level where distortion starts to increase, you can 'measure' just about any distortion you like, depending on the power level. Tube amps have comparable distortion to solid state at levels below this 'knee', which occurs near full power. Also, as you probably know, tubes have almost no distortion components beyond the 3rd harmonic, which is musically related (the octave + a 5th) In addition, and this is not well known, the phase of the distortion components is not corrupted relative to the fundamental as it is in solid state: they are in their proper in-phase condition, unlike solid state, which corrupts the phase of what distortion it produces. This is one very big reason that even comparatively small levels of distortion in solid state amps sounds objectionable. Tube amps have a far 'richer' biasing into class "A/B" than solid state, which produces less distortion at the crossover point in a push-pull amp: this must be made up for by high levels of negative feedback in a solid state amp. Tube amps use _much_ less global negative feedback than solid state, and avoids TIM (transient intermodulation distortion) entirely, unlike solid state. And finally, tube amps have power supplies which can store easily an order of magnitude more energy than solid state by virtue of the higher power supply voltages utilized relative to the filter capacitance. It would be all but impossible for a solid state amp to have enough filter capacitance to compete with a tubed amp in this respect. This means that tube amps do not modulate their power supply nearly as much as a solid state one.

And, do you REALLY think that I would use an amplifier that had as much distortion as you say in my system, which is used for critical listening to master, edit and mix music? I don't think so.

You still did not give specifics as to the actual amplifier (s), that Stereophile et.al. measured, and under what circumstances they measured them.

I really don't care if you like tube amps or not. What I object to is throwing out blanket comdemnations about something you have not actually had _direct_ experience with, having only read it in a magazine somewhere. How would you feel if I told you that a particular component _you_ have can't possibly sound good or be of any use as an _accurate_ sound reporducer, and have as my only backup something I read. I really am surprised you are willing to throw out opinions on something you obviously don't care to research, much less care about.

I've heard good things about the Van-Alstine modded Dynaco ST-70, plan to get the mod for my ST when I have time to fool with it. ST-70s are all over eBay.

http://www.avahifi.com/
http://www.netaxs.com/~vkalia/st70-rebuild3.html

But I'm far from a 'tube guy', so ask around.

SH - Any info on ST-70 mods/upgrades?

EDIT - The only gripe I have with tubes in general is the power/$$$ ratio is pretty low, but if you're using high efficiency speakers (or I guess if you have a lot of $$$) a lot of that goes away. I liked the way the ST-70 sounded back when I had it hooked up, and honestly the only things I noticed in that time were (1) it looked REALLY cool and (2) it was a bit anemic compared to my m1.5t. Nothing earth shattering there, is there?

[This message has been edited by charlie (edited January 13, 2003).]

Kevin:

Again you are taking an extreme example. I actually have a single ended class"A" triode amp that I use for my tweeters, and I get .04% distortion from it at levels below the onset of clipping. A class "A" single ended triode amp has an _exetemely_ broad 'knee' of the onset of distortion. Below that 'knee' the distortion is _much_ less. With a single ended triode amp, you could measure 20% or more distortion if you pushed it hard enough. IT DEPENDS ON WHERE YOU MEASURE THE DISTORTION!

m-mmeyer:

I'm not from Arizona, but I've been there a few times

There are quite a few manufacturers of new tubed amps now. Sonic Frontiers got their start building them, and might still make them. There are also some good ones that don't cost a lot from companies like Asusa, SoundValves (Sound Values) and others. I'm sorry I don't have a lot of names handy, but you can probably turn up some names with a web search. Of course you can pay BIG bucks for a tube amp, and I do not think that those are worth the money, but they sure have purty brushed aluminum faceplates. There are plenty of manufacturers of vacuum tubes (the tubes themselves) also, most come from Russia and other former eastern bloc countries, but they make good stuff.

tubes work if your heat pump dies. tubes...didn't he star in jurassic park??

at the show...
1.) sunfire cinema 7 signature 400wpc @ 8 ohms

2.) linn klimax 500w monoblock

3.) spectron class d musicianII 500wpc

sahweeeeeeeeeeeeeet! no toob-tester required

Charlie:

I don't think the mods are being made for the ST-70 anymore. The original circuit was pretty simple, and had some comprimises, but the basic guts like the transformers were excellent.

Yes, you are quite correct - you shouldn't buy a tube amp for 'bang for the buck"! You have to be very careful about what they are connected to. Generally, speakers that need a lot of power, and / or have complex crossover networks are not a good candidate. On the other hand, tube amps shine with horn speakers, in fact they are almost mandatory for high efficiency horns that have corssovers much below 2Khz. It's all a matter of application. The amp that drives my tweeter horns (1,200Hz and above) has only 5 watts, but with sensitivities of 106db for _one_ watt, I am asking for much less than one watt, even at ear bleed levels.

Bosso:

I only need _10_ Good watts....

Actually now, there are a lot of solid state designs that don't use much if any negative feedback, i.e., the Japanese in the early 90's using negative feedback to get great measurement numbers but poor sound. And the backlash against that.

Never condemned tubes. Just not for me. I guess here's some questions: for a 7 channel system, and wanting to play movies, multichannel audio at 75 to 85 dB with enough headroom to not get any distortion from overloading the amp, how much would that run for a tube setup? And then how often do you have to replace tubes to make sure that no sound quality degredation is occurring?

All fair questions when comparing the two.



No, of course not. You like the sound that you get. But I don't even like the idea of distortion. Kind of like being a germ-a-phobe. I had Velodyne servo subs for 4 years, and now a Vandersteen sub with FFEC (feed forward error correction) for the past 2 years, both manufacturer's use mechanisms to minimize distortion, for a reasonable cost, without going long-throw or big driver area.


All I know, is that the Rotel 1066 doesn't have a tuner, but the 950 does...

Excuse me I must have stepped onto the wrong elevator, I was looking for the 950 vs Rotel 1066. But I guess that thread went down the tube......