Why Tubes Sound Better than SS

Tyson · « **on:** 26 Mar 2009, 07:40 pm »

OK, maybe blanket statements are bad, but it is a fact that many, many audiophiles eventually find there way into tubes, and very few ever completely leave it once they have.

From an engineering standpoint it would seem that SS would trounce tubes, because they generally measure much better. But we always come back to the "there's something magic" about the sound of tubes.

The consensus seems to be that tubes are "adding" distortion (harmonics), and that distortion is pleasing, so we like it. But, ultimately it is claimed that tube gear is "not accurate", despite sounding good.

I have a different interpretation. I think that harmonics that occur naturally in life are stripped out during the recording process, which kills the "life" of the recording, and that tube gear restores some of that stripped out life.

pardales · « **Reply #1 on:** 26 Mar 2009, 08:29 pm »

A very interesting notion.

rajacat · « **Reply #2 on:** 26 Mar 2009, 08:41 pm »

Perhaps SOTA measuring devices are missing something. For instance, is there a way to measure the holographic presentation qualities of an audio electronic device?

Tyson · « **Reply #3 on:** 26 Mar 2009, 08:46 pm »

Perhaps the SOTA devices are measuring the wrong things

cujobob · « **Reply #4 on:** 26 Mar 2009, 08:51 pm »

Tubes are not inferior to SS devices in all ways. In some ways, yes, but not all. I don't know why I prefer my tube equipment over my SS I've had (except the wonderful First Watt stuff)...but there's a reason that is definitely measureable, whether we know what it is, or not.

Tyson · « **Reply #5 on:** 26 Mar 2009, 09:09 pm »

Actually I was reading some very interesting things from Joe Rasumssen's pages that might point us in a good direction:

Quote

Let's change subject slightly and ask: Why are high voltage lines so thin? Because the higher the voltage, the less current is required. There are fewer losses at higher voltages and cables also will sag less and run much cooler. Typically HT lines can be as high as 500KV, half a million Volts.

True or false, voltage does not compress, current does? Yes! The current is the problem.

Is this why many of us love valve amps? Does valve amps have superior and more natural dynamics because they are high voltage and low current devices.

Believe me when I say that is much easier to mess up power supplies in transistor amps that it is in tube amps. Typically voltages in tube amps are up to ten times higher than transistor amps and that means up to one-tenth the current.

Also, because AC is converted to DC, in typical power supplies the peak current drawn out of the transformer can be 7-10 times higher than the current required by the amplifier. So if the speaker requires 5 Amps, then the peak current drawn in your power transformer can be 30 to 50 Amps. AC has gaps in the power delivery, the power supply's reservoir capacitors in-rush current has to compensate. Yes, current is the problem.

Current equals dynamic compression unless very close attention is paid to it. Tubes are less prone to compression.

JakeJ · « **Reply #6 on:** 26 Mar 2009, 09:18 pm »

One item that is measurable and has been discussed in the press is that tubes add even-order harmonics and solid-state add odd order harmonics. Those that have presented this data state that our ears prefer even-order harmonics as opposed to odd-order.

I do not profess to be an engineering expert but having seen the data it make sense and that's what my ears tell me.

JakeJ

whubbard · « **Reply #7 on:** 26 Mar 2009, 09:44 pm »

Erm....
Please, ladies and gentlemen, no arguments about tubes vs. solid-state, both have a place in our audio universe and I own both.

But I'll continue. Personally, I feel that it music is not meant to be sterile. All professional pianists can play the same music, but its what they add that makes their performances special, its the way they play the music. I feel like the tubes are just 'playing' the music, adding to it, without taking anything away.

-West

Thebiker · « **Reply #8 on:** 26 Mar 2009, 11:01 pm »

Which is better as a result of measurements is irrelevant to my ears. My ears prefer the sound of vacuum tubes, valves if you will. I, like most, have owned solid state and at that time, thought it was great stuff and my HT is still SS and its fine for that purpose. But then, I don't listen to music on my HT rig.

In the late 90's, I was given an old Scott 222C. I took it home, cleaned it up, re-tubed it and fell in love. I hadn't heard music so rich and organic since sitting in Boston's Symphony Hall listening to Segovia.
I tried to escape the tube addiction. I brought home various $$$ SS rigs for in-home demo. Threshold and Mac were just two of several. But the old Scott kicked them to the curb

. How could that be?

After much frustration, I surrendered and submitted to my ears demands

. A Manley followed me home and stayed. Then a Cary followed me home and stayed.

Yes, I am a tube-a-holic. There are two tube 2-channel systems in my home at all times.....any less could cause me to go into withdrawal and I just hate polka-dot elephants

.

Walt

TheChairGuy · « **Reply #9 on:** 26 Mar 2009, 11:14 pm »

Isn't it great that there now is a devoted circle where one can post 'Why Tubes Sound Better than SS' and not catch barbs from the flat earthers?

I once posted something akin to 'Why Vinyl Sounds Better than CD' on the Vinyl Circle and it was so nice to be able to say it in the safe confines of the Vinyl Circle.

John

ratso · « **Reply #10 on:** 26 Mar 2009, 11:19 pm »

i am a 'flat earther' i think. i hate all forms of audiphile 'snake oil', from speaker cables to 'burn in time'. but i love tubes. why? i dunno. i just do. they sound good. they look good. people come over to my house and look at my preamp and go "what the hell is that?" and i like that too.

hmen · « **Reply #11 on:** 26 Mar 2009, 11:47 pm »

I really don't care why or even if tubes sound better. I just know they sound better to me.

acresm22 · « **Reply #12 on:** 27 Mar 2009, 12:24 am »

I'll throw out another theory...and I preface it by saying I'm a full-on tube believer, having been in the "tube owners" (say that really fast several times) society for 15-plus years:

We like tubes amps because they have limited or shelved down reach at the frequency extremes, thus softening highs, rounding lows and spotlighting the midrange. We (many of us anyway) like single drivers for the same reason. The fascination with NOS dacs and the Sony PS1 also applies. It's not much more complicated than that.

Discuss....

zybar · « **Reply #13 on:** 27 Mar 2009, 12:28 am »

Quote from: hmen on 26 Mar 2009, 11:47 pm

I really don't care why or even if tubes sound better. I just know they sound better to me.

Especially those OTL types... aa

George

topround · « **Reply #14 on:** 27 Mar 2009, 12:31 am »

I was at a Linn dealer once.
A punk kid, who worked there asked me what I used. I said tubes.
He said he didn't like tubes, they were too liquid for him!
I was amazed

He was young and stupid, that was his defense in my book
I think tubes has to do with maturity and eventually learning what sounds right and real

I know I will be blasted for what I just said

so go ahead

let the beatings begin

ginger · « **Reply #15 on:** 27 Mar 2009, 03:00 am »

Well - for what it is worth here is my opinion.

1st and foremost a tube (the triode) is the most linear amplifying device invented by man.

All else follows from that.
A typical SS Amp (order of magnitude figures) will have an open loop gain of 100,000 with a feedback factor of 5,000 giving a closed loop gain of 20.
A typical tube amp will have an open loop gain of 50 with a feedback factor of 2.5 giving a closed loop gain of 20.

I'm talking about a combination of local and global feedback here.

Any feedback signal is time delayed and smears time coherency. The more stages the feedback is applied over the worse that problem.

Tube amps therefore tend to sound more "correct" in terms of pace rhythm and attack, they are just (for want of a better adjective) more fluid and "breathe" with the music.

This tends to influence things like stereo imaging or "sound stage" and ambience.

Higher amounts of feedback tend to counter soft compression effects and make clipping harder and more abrupt. In engineering terms we say the transfer function graph (signal voltage out vs signal voltage in) is less smooth with more abrupt corners near the limits. The more abrupt a change in the transfer function the more higher order harmonics are generated. Anyone who has studied musical theory will know that the second harmonic of (for example) a C note is a C one octave above and 3rd harmonic is still musically related BUT by the time you get to 7th, 9th , 11th harmonic the "note" produced is musically unrelated to the fundamental, we call this musically "quint". While 1% 2nd harmonic distortion is "euphonic", about 0.01% of 7th harmonic is seriously objectionable and just grates like fingernails on the blackboard.

The more feedback, the more harmonic multiplication, that is the harmonic distortion products which are in the feedback signal are subject to further harmonic distortions which are then fed back to produce even more.

There are other things at work as well BUT I believe that the level of feedback is the major difference in the sound between SS and tube amps and that teh time coherency is at least or more important than the harmonic distortion profiles.

I design tube amps with local feedback around each tube stage, seldom over 2 or more stages, never over 3 or more stages, and in particular don't use "global" (from output back to input stage) feedback at all.

Just one mans opinion, but an opinion based upon designing and building both SS and tube amps over many years (I've given up the SS Amps now).

Does that mean I don't use SS at all - NO, my tube amp designs use transistor current sources in the "tail" of triode tube differential amplifiers on the input, I often use MOSFET Source Followers with transistor current source loads to drive the output tubes etc. BUT all of the gain stages are tubes. Also I borrow ideas from modern SS amp design to implement things like balanced shunt feedback loops (local feedback around only 2 stages).

Cheers,
Ian

Zero · « **Reply #16 on:** 27 Mar 2009, 03:07 am »

Quote

I have a different interpretation. I think that harmonics that occur naturally in life are stripped out during the recording process, which kills the "life" of the recording, and that tube gear restores some of that stripped out life

I agree 100%. That said, there are a handful of solid state components I've come across that can do that 'tube' thing exceptionally well, to the point to where I do not finding myself missing the glowing glass.

JakeJ · « **Reply #17 on:** 27 Mar 2009, 03:14 am »

Quote from: whubbard on 26 Mar 2009, 09:44 pm

Erm....
Please, ladies and gentlemen, no arguments about tubes vs. solid-state, both have a place in our audio universe and I own both.

But I'll continue. Personally, I feel that it music is not meant to be sterile. All professional pianists can play the same music, but its what they add that makes their performances special, its the way they play the music. I feel like the tubes are just 'playing' the music, adding to it, without taking anything away.

-West

So far I don't see any arguing, West. Just opinions stated in a polite and well-mannered way. I welcome discussions like this.

My experience is similar to most here. SS doesn't quite get it right where tubes do...for me. However, last summer I acquired a BEL 1001 MkII and have a new outlook on what a SS amp can do. Preamps are another story in my audio journey.

Cheers,
JakeJ

JoshK · « **Reply #18 on:** 27 Mar 2009, 03:25 am »

I think I could write a book about this, well not really, but there are IMHO quite a few reasons that are comfound to make a lot of tube lovers. But let me point out a couple things...

While it is true that tube amps generally produce more 2nd harmonic distortion (H2), this need not be so and in fact many PP pentode/UL amps can produce just as much odd order as solid state amps. Single ended amps tend to produce more even order distortion, particularly H2. Most SS amps that we are familiar with are class a/b complementary (like PP) amps. They also tend to have lots of FB which lowers H2 and H3 which are the largest parts of THD but raises higher order distortion components for which our hearing is much more sensitive and are much less agreeable. So THD is worse than useless.

If we are to compare SS to tubes on measurements, people use THD because that is all anyone seems to know how to measure, but its doesn't relate to how we hear. Tubes are much more linear devices and don't necessarily need as much FB to function properly, most all SS devices need lots. There are exceptions of course. Nelson Pass has been the reigning champion of showing the DIY world how it is done. Lots of his amps have harmonic distortion profiles that match that of good tube designs but are typically an order of magnitude lower.

There is the fact that tube amps clip softly due to the output transformer. This isn't true for OTL designs that clip just as hard as SS amps. They also employ just as much FB typically. The FB exacerbates the time constant to blocking distortion. What this means is that when an amp clips it takes the driver a split second to recharge the capacitances between the driver and output stages. The more FB generally the more prolonged the effect is and the more readily you hear the clipping. Some of why lower FB tube amps sound better might simply be that when they clip, you don't often notice.

Then there is the fact that because of the output transformers in most tube amps, it is hard to use a great deal of feedback. This means that you have to design the amp to stand on its on two feet first before the feedback. This is generally good design practice for any amp, but not all designers do it. Feedback is all too often used as a crutch to make good numbers. This causes all the problems above. With tube amps it is easier to design the amp good to start with and you can't hide behind feedback.

Don't get me wrong. I am not poo-poo'ing feedback, just noting how it has downsides too if not used judiciously.

There might also be the case that tube amps limit hard before they clip, leading to a more compressed sound when distortion starts to rise.

SS amps that use a lot of feedback tend to not have their best distortion numbers until higher up around 10 watts. They can often times have higher distortion at 1 watt or even .1watt then they do at 10 watts. Since most of our listening is in the few watts and less area, amps with a lot less feedback can actually have less distortion for most listening, this is can be contrary to the stated specs.

These are just some points to consider. There are many exceptions to all the above examples. Pass's First Watt amps are a great example.

I still don't get OTL amps though. I've only heard hmen's and didn't compare to anything else, so I can't draw any conclusions from what I heard. However, in theory it just seems that they have all the disadvantages of tubes (the worse case of heat and inefficiency) and none of the upside (soft clipping, lower feedback (they have enormous amounts of feedback by design), lower harmonic distortion order, etc, etc). I am sure there are some that sound nice and I know very respectable and smart designers who swear by the topology, but I don't get it.

rydenfan · « **Reply #19 on:** 27 Mar 2009, 03:26 am »

IMO, I think that the blanket statements about tubes and solid state no longer really apply. I think the design/advancement of each has been quite astounding. There is plenty of tube gear that some would call "solid state like" and plenty of solid state gear that one could say "has tube like warmth or midrange." I know that over the last few months my eyes (and more importantly ears) have really been opened up to this. I have certainly heard solid state gear that I would call more musical than tube gear, and to me, ultimate musicality is paramount. I truly believe that the vast majority of the sound of a particular component is greater determined by the designer of the piece and the voicing they create than some of the nuts and bolts used. Just my $.02