The attraction of vacuum tubes / valves. - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th February 2003, 11:43 AM   #11
7N7 is offline 7N7  United Kingdom
diyAudio Member
 
7N7's Avatar
 
Join Date: Jan 2003
Location: England
Quote:
Originally posted by Bas Horneman
Hi 7N7,

Yep that's another reason I love tubes..ruggedness...

But when building my frontrow amp a 6X4WA died when I connected 540v to the heater instead of 6,3V.



Ooops.

Cheers,
Bas
Ha - ha!

I remember an E88CC that survived 330V on its grid!

7N7
__________________
Plug them in and light them up
  Reply With Quote
Old 19th February 2003, 12:09 PM   #12
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
* 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.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 19th February 2003, 12:28 PM   #13
316a is offline 316a  England
diyAudio Member
 
316a's Avatar
 
Join Date: Dec 2002
Location: West London
Default 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
  Reply With Quote
Old 19th February 2003, 04:10 PM   #14
Joel is offline Joel  United States
diyAudio Member
 
Joel's Avatar
 
Join Date: Oct 2002
Location: Brooklyn, NY
I have to disagree on the "glow factor". I love the looks of the old octal metal tubes. A black 6F5 is a thing of beauty.
  Reply With Quote
Old 19th February 2003, 04:20 PM   #15
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
Quote:
Originally posted by SY
* 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.

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
  Reply With Quote
Old 19th February 2003, 06:37 PM   #16
paulb is offline paulb  Canada
diyAudio Member
 
Join Date: Jun 2001
Location: Calgary
Quote:
Originally posted by GRollins 11-28-2001 09:22 PM

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

what are the pros and cons of valve amps?
  Reply With Quote
Old 19th February 2003, 07:27 PM   #17
Joel is offline Joel  United States
diyAudio Member
 
Joel's Avatar
 
Join Date: Oct 2002
Location: Brooklyn, NY
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.
  Reply With Quote
Old 19th February 2003, 07:44 PM   #18
316a is offline 316a  England
diyAudio Member
 
316a's Avatar
 
Join Date: Dec 2002
Location: West London
Default 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
  Reply With Quote
Old 19th February 2003, 08:10 PM   #19
diyAudio Member
 
Join Date: Oct 2002
Location: Amsterdam
My girlfriend calls them pepper and salt shakers !!
  Reply With Quote
Old 19th February 2003, 09:32 PM   #20
RIP
 
pedroskova's Avatar
 
Join Date: Dec 2002
Location: C'ville VA, USA
My choosing tubes is no different than my choosing analog over digital. I do own a few dozen CD's that I'll play thru headphones on my PC while working, but I still refuse to add a CD to my main system.

It's all about aesthetics...both visually and philosophically.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
CCS for tubes/valves: PCBs SY Tubes / Valves 345 8th September 2013 11:01 AM
GE JAN 6072A Valves (Tubes) mozfet Swap Meet 1 2nd August 2008 02:34 PM
Another CCS for tubes/valves: PCBs Doc B. Tubes / Valves 77 23rd January 2008 08:10 AM


New To Site? Need Help?

All times are GMT. The time now is 07:23 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2