• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

The attraction of vacuum tubes / valves.

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Quite apart from the sound, I think tube equipment is way more interesting to look at than solid state stuff. Anyway, what I was thinking of is... would tube stuff have as great a following if all tubes were in metal cans instead of glass, therefore you could not look inside them and see what is happening when they are going. Being such good entertainment for the eyes as well as the ears gives them an extra facet of attraction but I wonder how many people would have taken an interest in them if they weren't so great to stare into when they are going?
 
Tube attraction.

You are right. The tube is attractive with the glowing heater and the transparent see through tube. I am glad that they sound so good also. Circuit wise they are easier to figure out and use less components in many cases.
I must admit that if they were only as good as a good solid state amp I would have bypassed them. They do have the the hassles related to high ( lethal!) voltages . I have been ' shocked ' so many times. Even if one is careful , it does happen off and on.
For people who just buy boxes and use them , this should not be a problem.
Tubes are great. I love them !
Cheers.
 
Circlotron said:
Being such good entertainment for the eyes as well as the ears gives them an extra facet of attraction but I wonder how many people would have taken an interest in them if they weren't so great to stare into when they are going?

We are emotional beings so certainly aesthetics, nostalgia, etc. will play a role in our enjoyment of reproduced music and subsequently have an influence on what we ultimately end up with.

se
 
Ex-Moderator
Joined 2003
Caveman feelings

It has to glow. Transistors are extremely boring things to look at, and to date the only scope for sculpture seems to have been in the heatsinks. On the other hand, who can fail to be warmed by the sight of one's cat stretched out in front of a set of output valves?

An alternative secondary use is that the radiant heat and glow from a valve amplifier in subdued lighting makes your whisky look and taste nicer.
 
It's oo easy with tubes

Simple circuits sound good from the start.
You don't have to care about distortion too much with tubes
because their distortion is what makes them sound so good.

With transistors you have to try a thousant times and the
music seems harder when distortion reaches very low levels.
(maybe bad Cd recordings is the cause ?)

It's unfair.
Maybe I am wrong, do you think so?
 
leon said:
It's oo easy with tubes

Simple circuits sound good from the start.
You don't have to care about distortion too much with tubes
because their distortion is what makes them sound so good.

With transistors you have to try a thousant times and the
music seems harder when distortion reaches very low levels.
(maybe bad Cd recordings is the cause ?)

It's unfair.
Maybe I am wrong, do you think so?


All the above points are well made and I agree that the aesthetics are important - I love valves and that's why I am in this mad hobby.

Another point in favour of valves is the staggering abuse a valve can take and survive. E.g. being connected incorrectly!

Just look at a transistor/IC in the "wrong tone of voice" and it will lay down and :dead:

7N7
 
* High heat.

* Environmentally unfriendly -it takes energy to run an inefficient amp- fossil fuels, nuclear, what-have-you. All that heat is just waste of natural resources

* Unreliable- tubes age, burn out, go unbalanced, drift, break... sorry, that's why they're not used much anymore. If you haven't had to replace cathode resistors because a tube shorted or replace electrolytics that gave up the ghost from high voltages and high temperatures, then you just haven't built and used many tube amps.

* Poor deep bass. There just isn't enough iron in this world

* Questionable sonic benefits- highish distortion, poor power bandwidth.

So why do I use tubes for my amps, crossovers, and preamps? Same reason I would drive a '58 Austin Healy Sprite or a '57 T-Bird- it's fun, it's nostalgic, it's got a coolness about it. I don't pretend that I'm getting some mysterious "X" factor from using tubes for music reproduction (a lot of controlled subjective testing convinced me of that) any more so than I could pretend that the '57 T-Bird will outrace a current model Porsche. But the T-Bird will turn heads and the Porsche (at least out here in California) won't.
 
Rugged Valves

On the subject of doing stupid things with valves , I once (early project) powered on the amp and wondered why there was no B+ . After much head scratching , found a small strand of wire shorting the cathode of the EZ81 to the chassis ! It worked perfectly once the wire was removed , goes to show that some valves can survive a dead-short . In fact the EZ81 were tested after a years use and although having slight blackening inside the glass , tested as new .

316a
 
SY said:
* High heat.

* Environmentally unfriendly -it takes energy to run an inefficient amp- fossil fuels, nuclear, what-have-you. All that heat is just waste of natural resources

The interesting part about this is, even triode amplifiers on the happy side of class B, *even counting heater power*, can be 50% efficient, with maybe 1% distortion at max power - no global NFB yet.
Switch over to pentodes, and you get a tremendous amount more power - the higher distortion (maybe 3% at max.) and high Zo can be nulled with still far less NFB than used in SS.

And it doesn't stop here, oh no - because everyone in the SS forum is always talking about class A and AB amplifiers. Class A is 30% efficient at best, and is constantly burning the same 100, 200W at zero as it is for only 20, 50W output!

Heat is only percieved; mix the hot air streams with as much air as passes over a heatsink and the temperature is just as cozy. Power is power, no matter how you cut it.

Oops, that sounds like a rant. Meh, too lazy to rephrase it so it doesn't sound like one. :cool:

The overall point is, tubes are as inefficient as 'top' modern SS designs, but they're more exciting (whose heart doesn't skip a few beats after being subjected to 400V? ;) ) and are far more beautiful.

Tim
 
GRollins 11-28-2001 09:22 PM said:

Cons...the ones not open to argument:
Heat--set aside the operating class, the filaments produce heat. It's the nature of the beast. Good in the winter. Bad in the summer.
Low damping factor--this can be improved somewhat by using good transformers, but tube amps simply do not get the kind of damping factor that solid state amps can do, at least not without a zillion dB of negative feedback (which is part of how solid state amps get such high damping factors), but then you're throwing away one of the better aspects of tube design. (Note that there's no agreement as to how much damping factor is 'enough.' Some tube amps [almost always high powered ones] are quite good in the bass in spite of having low damping factors. Go figure.)
Tubes--you have to replace them at intervals. How long? Depends on hard they're biased.
Cons...the ones open to interpretation:
Weight & size--this one almost evens out. Both tubes and solid state need power transformers, but only tube amps need output transformers. (Unless you want to go OTL...I'm working on it as fast as I can. If you're in a hurry, go find a published design out on the web.) However, solid state amps need heatsinks, which brings things nearly to parity. (Note that tubes have built-in heatsinks.)
High voltage--yes, this can be a nuisance, dangerous, even. On the other hand, you're not going to stick your finger in there, are you? On the other, other hand, I've been hit with jolts numerous times, and am still here. It hurts. You cuss. You go on to the next thing. Just be careful, and when you're not careful...cuss quietly.
In between:
Distortion--tube amps distort, and so do solid state amps. Tube amps generally (there are exceptions) measure as having higher conventional distortion than solid state (just for reference, a good tube amp will measure less than 1% distortion without trouble). But...tube distortion is of lower order harmonics, which are easier on the ear (no one disputes this part). Tube detractors invariably seize upon this and declare that people who like tube equipment 'like euphonic distortion.' There's no easy answer here, just make a choice. Hint--go listen to live music and choose the circuit that sounds more like the concert hall. Music is the benchmark, not measurements.
Pros (note that tube detractors will bitch about some of these):
Sound quality--exquisite, if the circuit is done properly. Tubes image like there's no tomorrow, something that solid state amps can approach, but have never equalled. If you like imaging, tubes are for you. If it ranks lower on your priority list, then the battle is somewhat more evenly balanced.
They look cool--some people don't like the look of glowing filaments. Personally, I think they need their heads examined.
They automatically protect your speakers--this is the flip side of using transformers. Even if a tube flames out, the most you get is a quiet pifft through the speakers. When a transistor amp goes down, it can sometimes take drivers with it.
Tubes clip more gracefully--this is sometimes expressed as 'tubes sound more powerful than equivalent power solid state amps.' When a solid state amp clips, it generally sounds pretty rough. Most tube circuits clip so softly that people don't even realize that they've hit the wall.
I use both solid state and tubes in my system. I like both, for what each does best. But don't let folks kid you, what tubes do, they do really, really well.

Grey

http://www.diyaudio.com/forums/show...96&perpage=15&highlight=opposite&pagenumber=1
 
Saying "tubes are weak in bass" or "SE has poor bass" is generalized nonsense. You can measure the exact performance at 20Hz.
It's fairly simple to get a tube amp to be at only -1dB at 20Hz. And choosing p-p does nothing to insure bass response. In fact, there is more opportunity to lose response, due to additional coupling in the inverter, or inductance if using an interstage.
 
Valves

Agreed about the bass but remember SE output stages have poor damping (usually without feedback) , with some highly reactive bass-reflex speakers there could be trouble . Into a resistive load yes , but into a reactive load , in some cases NO !

316a
 
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