Over time, you will have to re-bias your tubes, how much and when depends on how much and how hard you use your tube amp! Eventually tubes need to be replaced, you can hear when the tubes are shot, at the end of their lifespan they make noise, called Tube Roar, sounds like noise!
scottyj
I like older Levinsons, I also heard Krells, and Krell makes tight bass, but I find them edgy and kind of harsh in the upper mids and highs! If one can afford them as subwoofer amps, that would be my way to use them!Originally Posted by Alex Lancaster
Steve: Remember when I said "snake oil
?, I have not heard anything better than M Levinson or Krell, even moneywise, I do not want to spend that money, so I´m happy with a Crown K2, a Sony N77ES, and an N80ES.
For my mids and highs I still like my old Crown D-150A and Crown Power Line-2,s! The D-150A and JBL 2441,s work well together, they just do.
Jus my opinion!
scottyj
Steve, the harmonics generated by an amplifier will be at multiples of the frequency being reproduced. If you look at an amplifier producing a 100Hz. sine wave on a spectrum analyzer, there will be (hopefully much lower) spikes at 200, 300, 400, 500 etc. In musical terms, the 2nd (200) is an octave above the fundamental, the third is approximately a fifth above that, the third a fourth above that, the fourth two octaves above the fundamental. Going higher the harmonics begin falling awkwardly in between notes on the musical scale, which is one reason why they begin sounding like fingernails on a blackboard.You are correct- a major reason we can easily identify different musical instruments playing the same note is that they contain very different amounts of the various harmonics, which creates their recognizable timbre.
A weighting system as proposed by Lynn Olson would certainly cast the performance of the typical tube circuit in a different light, one that might agree more with listening impressions. Perceptions vary so much between individuals, though. At trade shows I encounter systems that are bright, shrill, edgy, bleached out, distorted, you name it. The exhibitor will appear to be quite proud of the sound he's getting- if it was my room I'd shut the door until I could figure out what's wrong.
Johnny, tubes do wear out over time. Mostly it's a matter of the cathode, whose job is to shed electrons, being slowly poisoned by the impure vacuum inside the envelope which impairs its emission capability. A well made tube used properly in a circuit will usually last several thousand hours, sometimes tens of thousands for understressed small signal tubes. There may be measurable changes in performance throughout their life, but practically speaking they sound good until they don't, then it's time to change them.
Electrons are particular, they have mass, right? So when a tube has been through a heavy/long work cycle, the vacume gets contaminated with this "matter" or erosion of plate material?. Very cool stuff to know. As for the weighting issue: when I see specs discussed and read that there are good/bad things about an amps ability to reproduce even/odd harmonics, that is saying that the amps ability to faithfully reproduce individual components of the whole signal that, in turn, makes up and gives whatever was recorded, its unique sonic signature? So, in other words, timbre distortion!. If I am following this correctly, I can see how this could explain the love so many have for tube amps. I know my Bud, Mr. David Brink, has EVERYTHING a person could EVER want as far as gear is concerned ( and it wasn't handed to him!), and he swears by tubes. Not for any other reason than that they SOUND RIGHT. I am VERY intrigued. Every layer of understanding is exciting with it's newfound promise. No more numbers game(s)!. When Mr. Jack Sproul explained to me the tube/SS difference, he mentioned that when the first good SS amps came out, they were hated for the "dry", "lifeless" manner in which they reproduced music. I now strongly suspect this is due to the manner in which they translate the "WHOLE" signal!. Don't get me wrong, I'm not going to just dump my SS amps. I will consult with David and also welcome any suggestions for an amp in the moderately priced range. I can't wait to hear my 375's driven by a sweet little EL34 based amp now!. I am grateful to you Steve (and others) for lifting the vail of confusion concerning tube amps. I can see where it could/will lead to having to find recordings that were thoughtfully recorded with the whole chain i.e.= record/mix/mastered with the right type of gear in each step!. Please give me your thoughts as to my stated understanding of your explanations. I want to get this right. Thank you and best regards, Steve G
To me, comparing the virtues of SS vs Tube amps is analogous to comparing a photograph to a painting of the same scene. Some will prefer the photograph because it is a more accurate representation. Accepting the fact that at times a photograph may be brutally accurate, they prefer a photograph's detail and accuracy. To others, the painting is more pleasing to their eyes. Even though paintings may not be as true a depiction of the scene, the way the artist blends the strokes, the colors and hues, especially in the case of the impressionists, the artist creates a world that some feel is more beautiful (or relaxing or pleasant, etc) than the harshness of real life. To say one is better than the other is a matter of preference.
The painting on the left is a faithful reproduction of a red wall. The photo on the right is of a white(?) car, near Paris(?)....
Widget
The very heart of this discussion is a fact finding mission. Those that have made up their mind absolutely about one or the other cannot hope to gleen anything from it. What is good is that I've learned some really interesting points about tube amps that were begging to be answered. From one model to another in any brand and type of amplifier, there are differences, so I don't for one minute expect a blanket statement to be true about the difference between the two types alone too. I have been a staunch defender of the SS crowd for 25 years. I am skeptical about tube amps still somewhat. Here's the BIG BUT (pun intended): there are SO MANY people ,whos opinion I hold in high regard, that own and enjoy them that I am curious to the point that I will seek out a good one to try and make my own mind up with my ears. I can lie to others but my ears have NEVER lied to me. I am now armed with some baseline information in which to do so and I'm thankful. TTYL, Steve G
Steve, as I understand it the cathode of the tube (which boils off electrons which are then attracted by the high voltage potential of the plate and controlled by the potential of the grid) is slowly poisoned by contaminants within the envelope. Impurities which remain inside the tube from the imperfect vacuum established when the tube was manufactured deposit themselves on the cathode surface, impairing its ability to release electrons. The silvery substance visible in most tubes is the "getter", a substance designed to trap and hold most of the impurities when the tube is manufactured. Sometimes a slight vacuum leak can introduce gasses into the tube later on as well.
In a push pull tube output stage, even order harmonics are cancelled out, leaving the odd order harmonics to remain. This skewed balance is thought by some to result in a less accurate sound. Single ended circuits do not cancel any harmonics, so they remain in their natural proportion. So, the THD will measure higher but here is another case where measurements do not necessarily correlate with listening impressions. Another aspect of single ended circuits is that the primary of any interstage or output transformers carries the standing current of the preceding tube; the audio signal represents a small variation in this DC current, and a slight varying of the magnetization of the transformer core. With a push pull transformer, the alternating audio signal causes the magnetization of the core to collapse and reform in the other direction with every half cycle of signal, placing the smallest, most delicate audio signals in the transformer's most nonlinear region. I think this is the key to why single ended circuits seem to pass so much more fine detail without alteration.
Porschedpm, in your analogy were you intending a solid state amp to represent the more detailed and accurate rendering of a photograph, and a tube amp to represent the pleasant but less accurate painting? We'll have to agree to disagree if this is the case, at least if the tube amp is an ambitious DHT SE design.
Steve G,
If you want to hear a really good tube amp to help you in your SS vs. tube exploration, I would suggest Cary. Their better amps are really great, and unfortunately way out of my price range. Audio Research and Conrad Johnson also make many wonderful tube amps. You can listen to a modded Dynaco, but then you are heading in to the realm of personal preference as some are pretty good and others are more like the photo I posted above. Some of Cary's more affordable amps are unfortunately also in this category.
Widget
Steve,
You have certainly got some very fine responses.
Some years ago when I was an active member of our local audio club we had numerous debates and demonstrations on SS versus tubes with amps.
In one test on my earlier JBLs we compared a bunch of SS amps and some tube amps incl Quad 405, Phase linear, Playmaster series 111, a Mullard tube 30+30, Cary Single Ended 7 watt.
Out of that lot the Mostfet Playmaster was the prefered SS amp and the baby Cary of the tubes. Surprisingly they sounded similar in tonal character and overall quality.
On the face of such comparions its chalk and cheese and apples versus applies unless your can identify the optimum load conditons for a given design either SS ror tube and aside from basic topology differences this is why there is such wide spread opinion imho. Under real load conditions an amplifier will exhibit all sorts of odd behaviour in one way or another despending on the design as they are all compromises. And cheap or not so good designs of either often taint opinions for a lifetime and create almost religious cult followings in both camps.
For example some tube amps are far from a pure voltage source, and with a speaker that may have a low impediance (or reactive) and at higher frequencies they sound mellow or fat at low frequencies if they have a dip in impediance in the bass. This results larger amounts of 2nd harmonic distortion as a result...some audiophiles even venture to call this musicality as it tends to be pleasing to the ear.
However a good value amp tends to have even amplitude of harmonic distortions across all frequencies, where as SS amps tend to have rising distortion with frequencies over 1000hz or so as a result of loss of open loop gain and falling feedback at high frequencies (A/B amps here). The effect of this and the switching distortions that ocurr in the output stage that are looped via the feedback (for correction) with increasing harmonics give rise the harsh nature of the run of the mill SS amps.
SS amps with mild or little feedback that are designed to be linear to start with tend to sound better subjectively. These also tend to be more expensive.
Given all the above its easier to make a tube amp using the best known topology and thats class A in either Push Pull or Single Ended. They don't mind getting hot and notably Cary makes excellent Class A triode amps.
However, the Fet has similar properties to the Tube and when designed correctly a Fet amplifier can produce suprisingly impressive performance and notably the Aleph Passlabs is an excellent Single Ended amp which shares many qualities of both tube and SS amps and can range in power from 30-200 watts.
Another SS amplifer designed by the late JL Hood (who was a consultant to Toshiba and other semconductor manufacturers) was in fact a challenge to the Williamson Valve amplifier of the 60's and Hood claim he could not hear the difference. I have built this amp and have no reason to challenge this claim as it was subjectively superior to the modern day Cary 35+35 Push Pull Class A amp.
Steve, try as many amps as you can. In the end its a tasting exercise and how they all blend with you system, but stick with a good vintage of each type of amp.
regards
Ian
Ian, I will do just that! Refreshing to see this get back on track and go somewhere meaningful, Thanks again to ALL you Gentlemen.
My 2(where's the cents key?????) after my month or so of hybrid system (tubes on top ss on bottom), listening experience has been very positive. Cd's I considered unlistenable have become a joy to play again, much like the transition from metal/plastic horns to wood, not quite as dramatic but a definate improvemnt none the less. I find the sound much more detailed and yet not harsh like you get with excess top end sometimes. The midrange on good recording, wraps literally wraps around you. With 4" voice coils like in the 2235h's I found the bass on the weak side. Other speaker combo's are probalby better suited to use with small SE amps like the I'm using, a 10 watt single ended 6l6gc unit.
Kelly
I am looking at tube amps for the top end of my system (2395/375 combo/076). I have a feeling that the only reasonable way for me to go is SS on the bottom. I dare think that I could afford a powerful enough tube amp in a stereo/fullrange set-up. I've got to get some JBL electronic crossovers to start this testing with. looks like this summer is a good time to start. Thanks again for the input, Steve G
I use a Urei 525 on my set up. I works great, very flexible, unfortunately not the best looking component I've ever seen but who really cares as long as it works and that it does well.
Kelly
The San Francisco chapter of the AES has an interesting meeting coming up on a similar subject - analog vs. digital processes and recording:
March 2005 Meeting Notice
<TABLE cellSpacing=2 cellPadding=0 width=564 border=0><TBODY><TR><TD width="28%">Subject:</TD><TD width="72%">Old School/New School</TD></TR><TR><TD width="28%">Speaker:</TD><TD width="72%">Paul Stubblebine</TD></TR><TR><TD width="28%">Place:</TD><TD width="72%">Coast Recorders, 1340 Mission St, San Francisco, CA</TD></TR><TR><TD width="28%">Time and Date:</TD><TD width="72%">March 22, 2005, 6-10PM
</TD></TR></TBODY></TABLE>
Join us for a tasting of two approaches to music recording. In the
large room at Coast Recorders (a Bill Putnam-designed room) a band will
be set up to record. There will be two parallel recording chains: on
one hand a bunch of outmoded old tube mics, feeding a lot of
old-fashioned gear and a hopelessly out-of-date analog recorder. On the
other hand, a lot of sleek, modern, solid-state mics, into current mic
preamps and a digital workstation loaded with plugins. Hear for
yourself as we switch between the two. (Caveat: this is just for fun.
Please, no wagering.)
Address:
Coast Recorders
1340 Mission St, San Francisco, CA 94103
Tel (415)863-6009
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