Tube amps! Why use them?

nascarmann · June 2002

This is something I know very little or next to nothing about. What are the pros and cons with tube amps? How do power ratings compare? Is 50wpc tube the same as 50wpc SS? It would seem to me the 50 wpc tube must punch harder? Will it? Someone jump in here and tell me about tubes? (madmax, BDT, Russmann, hoosier21 and the rest)

phuz · June 2002

From what I understand, tube amps have a warmer, richer sound. They also look cooler.

mantis · July 2002

I think tubes sound more natural on most speakers, not all of them but most.Tubes always sounded warmer to me as well.Good drive with lots of reserves.Also can calm down bright speakers.
Tubes you have to maintain, buying new tubes about once a year depending on how much you run them.They also sound better after they have been on for awhile.They need to be hot inorder to sound fantastic.
I wouldn't buy a amp just because it was tubes or not.Sound quality with your speakers"Mating"is how you buy an amp.
Solid state and tubes today are very good.Not as many tube amps on the market as solid state.
They do look cool don't they!

Aaron · July 2002

Disclaimer: I'm far from the expert here, but I have a bit of knowledge on the subject.

What are the pros and cons with tube amps?

pros:
- the "tube sound" (warmer, smoother, etc.)
- cool factor

cons:
- tubes wear out
- amp has to warm up to get optimal sound quality

How do power ratings compare? Is 50wpc tube the same as 50wpc SS?

No. I'm not sure that there is a magic conversion number. It's pretty rare that you'll see any tube amps above 100W, and if you do, they'll cost you a bundle. It seems like decently powerful tube amps run in the 30-50W range.

Aaron

gidrah · July 2002

Yes, tubes are warmer. Then again I've never heard an acoustical live show that I would characterize as "warm".

Tubes have are known to be able to drive difficult loads (ie. 2 ohm loads) and produce a soft-clipping. This is usually not detrimental and can be treated as "oh well, it's just not there". SS usually hard-clip. They continue to send the full force of music and wind-up blowing a speaker. Most of us will agree that most speakers are blown by inadequate amplifiers (they clip before the sound wave is completed) that have no dynamic range. My 100wt (x)rcvr blew a 175w speaker, while a 30w speaker didn't even distort. I've never heard of anybody blowing a speaker on tubes.

I've heard people say that X watts tubes is equal to 2 or 3 watts SS. This may be attributed to the extended dynamic range.

All speakers have a continuously changing impedence. Damn that nominable BS. Some vary more or less than others. This degree of variance can dictate the benefits of a quality amp. The greater the variance the more a tube or expensive SS amp is needed to compensate. Theoretically a speaker with a straight impedence would sound identical with any amplifier able to drive it to it's full potential (shear watttage).

Depending on your usage, some tubes can last a number of years. But I would suggest something that can be easily replaced. Don't buy something that can only be replaced with NOS. Electro-harmonix makes some splendid replacement tubes.

RuSsMaN · July 2002

Because we all know tubes are 'cool'

-R

Ron-P · July 2002

The Tubes are cool. Remember such great songs as; "She's a Beauty" and "Talk to You Later"?

Peace Out~:D

RuSsMaN · July 2002

I have the 45rpm single for each of those, pure GREATNESS.

Cheers,
Russ

hoosier21 · July 2002

I have the LP's, I have to get a turntable, I have 5 boxes of 12" wasting away.

HBombToo · July 2002

Nascarmann, I know a little about Tubes because my first job out of school was with Litton Industries as a Power Tube Engineer. What a tough,complicated and process oriented this OLD technology is... but proven and reliable if done right.

The reason we hear cleaner, warmer and lower noise by the tube is that a tube requires no bias voltage to amplify, "It is always ready". In a transistor we dope the wafer with either plus or minus dopants and the Bias, or voltage potential across the junction is what causes electron flow. As the sine wave crosses through 0 Volts within the bias region the semiconductor shuts off. So in an AB type amp or Push/Pull there is a brief moment in which nothing happens. "Distortion of the signal". Without getting into some really cookie stuff, in short, "HATS OFF TO OLD TECHNOLOGY".

HOPE THIS HELPS A LITTLE:)

RuSsMaN · July 2002

Dopants, Bias. Well, I'm totally clear on tubes now....

Dumb it up a little HBomb, peel the onion, break it on down....

Cheers,
Russ

HBombToo · July 2002

I have some meeting I have to go to but after work I'll drink a 6pack and jump back in...

TroyD · July 2002

Dopants and Bias......hey weren't they drafted by the Celtics a few years ago?

BDT

nascarmann · July 2002

I have some meeting I have to go to but after work I'll drink a 6pack and jump back in...

Yeah,

You got sum splanin to do

madmax · July 2002

Tubes?

Pros:
You can hear many more small sounds (detail) at the same time.
They sound better when you look at them.
They respond well to tweaks.
They scare off the normal Best Buy audiophile.
They warm the heart and the hands on a cold day.

Cons:
You have to wait 30 to 40 minutes before they really sound good.
They should be replaced after about 3000 hours.
The AC comes on more often.
You can hear the SS distortion clearly after a good listening session with tubes.

madmax

Aaron · July 2002

You're bringing back memories of my EE classes. No!!!

Aaron

jcaut · July 2002

Hey! I had a few of those EE classes myself! Aside from a dopant here and a bias there, I thought that was a pretty good explanation. Hmm.. Maybe I DO need a tube amp....

What about a class A, or non-switching SS amp? Is the purpose to emulate a "tube" sound? Don't tube amps generally have a low damping factor, making it difficult to produce tight, hard-hitting bass? Just curious. I could probably research that and come up with my own answer, but I'm lazy and figure it's easier to just ask.

Jason

HBombToo · July 2002

Do not turn your tubes OFF!!! Why? because thermal variations may cause a leak in the glass over time...
Power cycling a tube is good for the manufacturer but bad for the user.
A Tube has a cathode which becomes a source for electrons due to heat. Its called a thermionic emmitter. A substance such as Barium Oxide, to list only 1, on a sheet of say Nickle becomes a great cathode. As the potential from the grid, or multiple grids, is applied, from the input signal, electrons due to the EMF move in the direction of the +Plate. "High current low noise AMPS are a result." There are differences between quatrodes and pentodes as to the grid geometry but they all fundamentally work the same. The whole deal is... A tube is always ready when HOT, NO waite time, and the more we turn the tube on/off the more stress we put in the glass. If oxigen gets in the glass the tube is HISTORY or, say, the barium oxide is no longer an emmitter.

I just got off my hall pass in which many BEERS were consumed so please excuse my rampage.

Hbomb

LiquidSound · July 2002

Yumm..beer.
Yumm..tubes.

LiquidSound · July 2002

No idea of the sound quality, but wow.

nascarmann · July 2002

HBombToo

Your knowledge is amazing in this area. Could you try explaining this as if you were talking to..........oh lets say a 7 year old so I can keep up!

BDN

HBombToo · July 2002

LiquidSound, That is a great link! Soon, I hope that the traveling will stop and I can buy a house with my OWN man cave. My man cave will be called the Pentagon, with raised ceilings so that no 90 angles are in the room.
I will go with TUBES as long as the POOL don't bankrupt me.

madmax · July 2002

So lets say the advertised life of my tubes is 3000 hours. If I leave them on continuousely vs turning them on for 6 hours a day how long will they last? Will there be any benifit from leaving them on? Lets say the 3000 hour value is considering they will always be powered. That would be 125 days. At 6 hours per day that would be 500 days. What do you think the rating is based on, always powered or intermittant use?
madmax

LiquidSound · July 2002

I say the theater has priority. The pool can wait.
When you say 'raised ceilings' to get rid of 90 deg. corners, exactly what do you plan on modifying structurally?? Or are you building a room from scratch?

HBombToo · July 2002

Nascarmann... I don't know what to say because the last thing I intended was to write a useless post. I just wanted to share my experience... I guess the best thing that I could say about Tubes are in my opinion, for a PreAmps is, TUBES are the BEST. " No Distortion". (I was a tube engineer but that was a long time ago....)

HBomb

nascarmann · July 2002

Nascarmann... I don't know what to say because the last thing I intended was to write a useless post.

Was not saying it was useless. Just hard for my big heed and little mind to follow.....:D

nascarmann · July 2002

She-at! Have I offended someone esle?:(

ziplin · July 2002

Had old Audio Research D-100 Tube Amp, 100 watts Per channel. Eight tubes that glowed warmly in the dark. Sounded warm and seductive. Then came time to think about replaceing the Tubes ( about a year and a half of continueous use) Andy's vintage tube service in MN. offered new old stock tubes of a price tag of $700.00 for all. Broken hearted I realized the maintence of the Amp was much more than I could continue to keep up with.
Sure I miss the sound, beauty, and aura of the tubes, but to tell the truth I think a lot of todays solid state electronics have improved over the years to actually give tubes a bit of a run for the money.:)

HBombToo · July 2002

Nascarmann, No offense taken here bud, I just want to help when I can.

LiquidSound
I would hope to build the room from scratch. "I Hope". The wife likes the idea so maybe:)

A Tubes Life
When we rated the life of a tube it was under maximum load. The 2 mechanisms that are responsible for a tubes demise is a leak or the cathode shoots craps. If we leave them on not under load then the cathode is in a quiescent state and no loss of cathode material. As we turn the tube on and off the expansion/contraction of the glass can leed to a leak.

In our test units for some of the real high power stuff we never shut the modulators down, just let them glow nice and pretty like, and the tubes lasted for 4 or 5 times the rated life.

I think that ziplin makes a great point regarding Tubes vrs Semiconductors. The relatively new mosfet technologies really, really good stuff.

mantis · July 2002

this is a effin good post........I love the **** out of it.
Yeah man thats what I'm talking about!!!!!!!!!!!!!!!!!!!!
HBombToo,
Kepp it coming man ............I'm sucking it all up......my man!!
Leave that alone you sick F%%%S

nascarmann · July 2002

The relatively new mosfet technologies really, really good stuff.

HBombToo

The mosfet technology is good if you are not building a high powered amp.....and bipolar is still the technology used in most high end units. Cost is the biggest factor with the mosfet against bipolar....less engineering costs with the mosfet? Mosfet amps will not drive low impendence loads like bipolar amps will at high power levels......if you intend to drive speakers such as the SDA-SRS or 1.2's a mosfet amp would not be the right choice IMO.....they do not like low impendece loads......

Tube amps! Why use them?

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