The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    Output tube life expectancy in Triode vs. Ultralinear mode.

    Share

    Kentley

    Posts : 295
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Kentley on Wed Dec 30, 2015 5:06 pm

    Wondering if one might expect longer tube lifetimes in triode {in ST-120 and M-125} due to the halving of output in triode???

    peterh

    Posts : 641
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by peterh on Wed Dec 30, 2015 6:56 pm

    Kentley wrote:Wondering if one might expect longer tube lifetimes in triode {in ST-120 and M-125} due to the halving of output in triode???
    I don't think so. You still have the same current and power losses within the tubes.

    Kentley

    Posts : 295
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Kentley on Wed Dec 30, 2015 8:37 pm

    "I don't think so. You still have the same current and power losses within the tubes."

    That certainly makes sense. So much for wishful thinking.....Thanks, Peter.

    Tube Nube

    Posts : 603
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Tube Nube on Thu Dec 31, 2015 12:52 pm

    I don't like the sound of triode mode, myself. Perhaps its dependent on the type of music.

    Kentley

    Posts : 295
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Kentley on Fri Jan 01, 2016 11:50 am

    Tube Nube wrote:I don't like the sound of triode mode, myself. Perhaps its dependent on the type of music.


    Triode/Ultralinear preference is not only highly subjective, but also undoubtedly highly system-synergy related. Technically, as I've read, ultralinear is lower overall in distortion and wider in frequency response. That said, it isn't necessarily "better" in your system with your music pumping into your ears. Remember -- all music-reproduction eqiupment involves a complex series of compromises. Something as slight as a change in rectifier can change the entire soundscape. I'll shut up now. geek

    Tube Nube

    Posts : 603
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Tube Nube on Fri Jan 01, 2016 12:07 pm

    No, no, Thanks for that!

    The most notable thing I hear is the loss of output power--no problem there the volume knob cant resolve. Next, though, is the almost as obvious loss of detail. Muted fidelity, is how I'd characterize it.

    Though I do think that might help matters on my Carpenters record. I can't say why birds suddenly appear, but I can say that when those horns suddenly come in, too loud and brash, it's unpleasant.

    Ahhhh Karen Carpenter. What a voice. What a tragedy.

    Bob Latino
    Admin

    Posts : 2374
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Bob Latino on Fri Jan 01, 2016 12:27 pm

    In a tube amp that has both ultralinear and triode connections, tube life should be the same whether you use either mode of operation. Voltages on the screens and the plate will be basically unchanged and the bias point will be pretty much the same. If you want to get really picky then try measuring bias in your VTA amp in ultralinear mode and note the value. Now switch to triode mode and note that the bias will drop less than 1%. The B+ voltage is also basically the same no matter which mode you have the amp set in. Yes - ultralinear mode has noticeably more power but that is because it is a more efficient way to use the output tube as an amplifying device.

    About a year and a half ago I had a post on ultralinear output stages in tube amplifiers. This post also contains two links with some technical info on ultralinear, pentode and triode output stages. If you have not read the two links and this type of info is of interest to you, check out our forum post at the link below.

    History of the ultralinear amplifier

    Bob

    Kentley

    Posts : 295
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Kentley on Fri Jan 01, 2016 12:32 pm

    Karen in triode mode was a fine singer. However, in ultralinear she was, unbeknownst to many, a superb drummer. Go figure. scratch

    Seriously, tubenube's observations are perceptive. Here's what I've found just recently (trial-by-error, as usual). ST-120. Weber WS-1 SS recti.
    The increase in B+ is significant. Bias pots must be lowered quite a bit. With the extra "oomph" triode mode sounds more natural. Evrything is a give-and-take. BTW in my situation, the AC mains voltage is 116-118 VAC. That leaves me currently {har har} with a B+ pretty much in the middle of the range recommended by Bob of 370-410 (approx. 390). It's a complex world.....

    Bob just put his wisdom in the mix. His points are well-taken.

    Tube Nube

    Posts : 603
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Tube Nube on Fri Jan 01, 2016 2:36 pm

    Say, maybe that's something for me to try...

    bluemeanies

    Posts : 120
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by bluemeanies on Fri Jan 01, 2016 8:19 pm

    Kentley wrote:Karen in triode mode was a fine singer. However, in ultralinear she was, unbeknownst to many, a superb drummer. Go figure. scratch

    Seriously, tubenube's observations are perceptive. Here's what I've found just recently (trial-by-error, as usual). ST-120. Weber WS-1 SS recti.
    The increase in B+ is significant. Bias pots must be lowered quite a bit. With the extra "oomph" triode mode sounds more natural. Evrything is a give-and-take. BTW in my situation, the AC mains voltage is 116-118 VAC. That leaves me currently {har har} with a B+ pretty much in the middle of the range recommended by Bob of 370-410 (approx. 390). It's a complex world.....

    Bob just put his wisdom in the mix. His points are well-taken.

    Hi Kent...Happy New Year to you and your family...and to all here on the forum!
    Not exactly the subject matter here but it is part of the mix. I have been putting off for some time introducing 2more output tubes into my m125's...not for power but the extra "oomph" for my translation means an increase for mid-range and tweeter performance. I have heard that the introduction of the additional output tubes would only increase bass response.
    Personnly, I don't know but I think this week I will do some listening with a lot of observation...in triode mode....always.
    You can only push the envelop so far...sometimes I think we all get a little anal to think changing a tube here or there will make all a dramatic difference and we seem never to be content with the obvious..."it perfect as it is"..."don't fix what is not broken"...but then this why this hobby never peaks!

    Kentley

    Posts : 295
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Kentley on Sat Jan 02, 2016 9:21 am

    Thanks, Mr. Meanies. Greetings to you and yours.

    First, it is difficult to predict what potential one might unlock from adding the full complement of output tubes in your particular circumstance. By all means, go ahead and try it. You will not be wasting anything, as these new tubes would serve as backups and be used eventually.
    I'm sure you know that a doubling of power won't give you twice the volume. It might be a few db, just as it is when one switches from triode to ultralinear. The reason why the general wisdom is that the increased "beef" will influence bass more than mids and highs is simply that the vast majority of power is used to reproduce bass. Also, remember that, under reasonable listening conditions, you are undoubtedly using only a fraction of the potential of those M-125s.
    Knowing your specific listening environment through audiobill, I might suggest once again that you will get much more cleanliness in your mids (particularly) if you redefine your acoustic space. Get those speakers away from the outer walls! Or treat the walls so that they "disappear" from the equation! That will clean up your sound much more than any alterations you could make in electronics.
    Keep in touch. We do have much in common vis a vis our equipment and our listening rooms. And we're both OCD old farts. tongue

    Kentley

    Posts : 295
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Kentley on Sat Jan 02, 2016 10:54 am

    Bob, I just spent 45 minutes scanning the articles you posted on "Utralinear" mode, and, though my tech comprehension is fairly low, I gleaned enough to begin to understand how this all works and what it means to the listener. I see that ultralinear is an ingenious use of negative feedback to control a pentode so that it sometimes acts like a triode. A "best of both worlds" scenario.
    Becase, as you deftly summarize, UL is a more efficient way of using the same voltage to produce higher output, perhaps the opposite to my original theory might be true - that UL may actually be more conducive to long tube life than triode, not to mention less stressful on the entire circuit. Anyone care to comment?


    Last edited by Kentley on Sun Jan 03, 2016 8:42 am; edited 1 time in total

    sKiZo

    Posts : 1285
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by sKiZo on Sat Jan 02, 2016 2:19 pm

    I find that triode mode is quite tasty for laid back jazz and soft instrumental ...

    I've been known to roll with either when I'm feeling laid back and soft ... which ain't all that often ... ROCK ON!!

    PS ... If in triode, I actually prefer it at lower wall current using the bucker. Then again, UL may lose a bit of punch at 116vac, but it more than makes up for that in low bass definition ...

    In any case, nice to have the option available.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by deepee99 on Sat Jan 02, 2016 7:46 pm

    Tough call. I think it's a Ford-Chevy thing. And yes, it is nice to have the option. I use Pentode mostly and like it just fine for low-volume listening. Probably depends on your speakers and preamps and other inputs.

    Sponsored content

    Re: Output tube life expectancy in Triode vs. Ultralinear mode.

    Post by Sponsored content Today at 8:11 pm


      Current date/time is Mon Sep 26, 2016 8:11 pm