Does a little tube distortion really matter?

[Ski Bum]

SS amps that have ultra low numbers have a different sound that some people may like, quick and good transient response

 

Note in the excerpt how the edge harmonics affect transients.  The tube amp may have subjectively superior transient response as a direct result of the amp's behavior.  A more well sorted amp may produce the source material more accurately, but the subjective results may be less stimulating.

 

 

 

Distortion? Not hearing it.

 

 

You're hearing it, although you may not recognize it as distortion per se.  (I've had Decware amps like yours on the bench, and saw copious amounts of 2nd through 5th harmonic even at low levels.)

Edited August 13, 2015 by Ski Bum

[minermark]

Distortion ?

What ?

Where ?

When ?

Maybe that is why the neighbors complain

 

After brief thought, My whole life is based on distortion, at this point, id have it no other way

[derrickdj1]

It is interesting that tube amps benefit from the overload mentioned in the article.  I can see why  low watt tube amps are utilized for so many 2 ch people.  Now looking again at the overloar so SS amps, they don't reach that point with Klipsch speaker because it does not take as many watts to get loud.  So, a descent sound can be appreciated but, without at much of the benefits as tube amps behavior?  This makes me wonder how much does a tube preamp contribute to the sound and what is the mechanism?

[Ski Bum]

It is interesting that tube amps benefit from the overload mentioned in the article.  I can see why  low watt tube amps are utilized for so many 2 ch people.  Now looking again at the overloar so SS amps, they don't reach that point with Klipsch speaker because it does not take as many watts to get loud.  So, a descent sound can be appreciated but, without at much of the benefits as tube amps behavior?  This makes me wonder how much does a tube preamp contribute to the sound and what is the mechanism?

Regarding ss power, too much is just enough, as you never want it to clip, ever.  Technically speaking, that "decent" sound as you describe it, attained from unclipped ss power, is more accurate.  But this thread is not about accuracy, it's about the glories of a little distortion.  Flea watt single ended, you do get some "benefit" from their (mis)behavior, at least up to the point you don't.  Gross clipping still sounds pretty gross.  Klipsch sensitivity allows even single digit power to suffice, which typically has us tube guys landing in a real audio happy spot: 75-85db average levels, with just enough headroom (or faux headroom as it may be).  That happens to coincide with human hearing's most sensitive range, which is advantageous for peering deep into the mix, yet never brutalizes your ears with truly high spl, hence marathon listening sans fatigue.    

 

Another point from the article, relevant to your last question, is that these benefits are realized specifically with tube amps connected to transducers.  A tube pre-amp, buffer, or line stage may or may not add any harmonic coloration, it all depends on the design goals.  It's pretty easy to pull of a squeaky clean tube line stage which would add nothing, or one that would embellish with some low order harmonics to add some meat to the bones.  I've tried this approach, paired w/ ss amps, and just don't find it as tubetastic as the amp/speaker approach.

Edited August 13, 2015 by Ski Bum

[oldtimer]

There have been some who swear by the tube pre/ss amp approach.  Your mileage may vary.  Excellent post ski bum.

[tube fanatic]

Fjd, thanks for posting that article.  The conclusions seem to lend credence to the often heard comment that "tube watts play louder than solid state watts."  And Ski Bum's statement, "Klipsch sensitivity allows even single digit power to suffice, which typically has us tube guys landing in a real audio happy spot: 75-85db average levels, with just enough headroom (or faux headroom as it may be).  That happens to coincide with human hearing's most sensitive range, which is advantageous for peering deep into the mix, yet never brutalizes your ears with truly high spl, hence marathon listening sans fatigue," coincides with my own experiences when I owned K-horns.  The levels cited are those at which I typically listened, and needing only 30 or 40 milliwatts/channel to achieve those levels sure made it easy to use the flea-power amps.  No one believed that I was driving them with so little!  I'd sure like to see the company capitalize on the power issue by mentioning that some listeners use very low power with their speakers.  The public has no clue about this.

 

Maynard

Edited August 13, 2015 by tube fanatic

[Ski Bum]

There have been some who swear by the tube pre/ss amp approach. Your mileage may vary. Excellent post ski bum.

If you think about it, the two approaches are doing quite different things. In the case of a tube pre, you're adding whatever the tube circuit's harmonic output to everything, the quiet passages, the crescendos, everything. With a tube amp coupled to a speaker the process is more dynamic (clean at low output, more harmonically embellished with higher output).

[oldtimer]

The public has no clue about this

 

Dude.  The public do not have stereo systems dedicated for music.  A clue would still mean nothing to them.   Now if you want to advocate a tube based surround home theater/music system...good luck with that...

[Fjd]

I posted this Nelson Pass quote in another thread.

 

 

To add to the Nelson Pass quotes, "IM distortion is the elephant on the dance floor.  Much of the time IM distortion simply forms a complex 'noise floor' which masks musical detail. At lower levels, it takes the life out of the music and makes it uninteresting, even irritating. It isn't as noticeable with very simple music, but it stands out with orchestral material as if the instruments were covered by a veil. At high distortion levels, the sound simply turns to mud, and we turn it down."

 

 

 

Given we now have this thread regarding certain aspects of tube distortion (e.g., harmonics), I thought the entire Nelson Pass article may be of some interest to readers since the article is written in a "plain English" style and a person does not need to be an electrical engineer to understand the points. 

 

I've included the link below and attached a pdf for those interested.

 

https://www.passdiy.com/project/articles/audio-distortion-and-feedback

distortion_feedback.pdf

Edited August 15, 2015 by Fjd

[Ski Bum]

I posted this Nelson Pass quote in another thread.

To add to the Nelson Pass quotes, "IM distortion is the elephant on the dance floor. Much of the time IM distortion simply forms a complex 'noise floor' which masks musical detail. At lower levels, it takes the life out of the music and makes it uninteresting, even irritating. It isn't as noticeable with very simple music, but it stands out with orchestral material as if the instruments were covered by a veil. At high distortion levels, the sound simply turns to mud, and we turn it down."

Given we now have this thread regarding certain aspects of tube distortion (e.g., harmonics), I thought the entire Nelson Pass article may be of some interest to readers since the article is written in a "plain English" style and a person does not need to be an electrical engineer to understand...]

Thanks for bringing this up, as I've been curious about this.

I'm not quite sure I fully agree with the interpretation of the I'M distortion as merely a "complex noise floor." It's the combination of 2nd and 3rd harmonics that is responsible for the synthesized bass, which is more tonal coloration than noise. Of course, as pointed out, most of the I'M products are dissonant, so my guess is that the truth lies somewhere in the middle.

Another thought, if that spray of I'M distortion is transient, only occurring during the highest peaks in the recording, what are the implications? At lower output levels, which is where we spend most of our time, where distortion may not exceed 2 percent or so, does this I'M mediated noise floor even get a chance to build up? Transient distortion is largely unrecognizable, provided the amp recovers from the clipping without further issue.

[Don Richard]

The entire article is from the Journal of The Audio Engineering Society, May 1973 and titled "Tubes Versus Transistors - Is There an Audible Difference" and was written by Russell O. Hamm of Sear Sound Studios in NY. https://archive.org/...dibleDifference

 

It is important to note that the AES article was written in the early 70s, approximately 7 years before the first MOSFET amplifiers were sold. The article's assessment of transistor distortion was for bipolar transistors, which control collector current by the amount of current into the base. MOSFETs are transconductance devices, where a static voltage into a high impedance gate controls source to drain current. Vacuum tubes are also transconductance devices. The circuitry used with MOSFETs is similar to tube amplifiers and so is the distortion spectrum. These days, saying , "Transistor amplifiers have higher order distortion components than tubes" is incorrect when various types of MOSFETs are used. 

 

Also, the distortion tests were run at overload. Normally, an amplifier of sufficient power is not operating in it's overload range. This will change when an amplifier that is too small is used. For example, if a person has a 5 watt amplifier hooked to their Cornwalls playing at a 1/4 watt, when a 13 dB peak comes through 5 watts will be required. This amplifier will be starting to over. If a peak greater than 13 dB comes through it won't be able to reproduce that peaks at all, and the sound will fall apart - for how long will depend on the amp's overload recovery ability. 

Edited August 18, 2015 by Don Richard

[artto]

Fjd, thanks for posting that article.  The conclusions seem to lend credence to the often heard comment that "tube watts play louder than solid state watts."  And Ski Bum's statement, "Klipsch sensitivity allows even single digit power to suffice, which typically has us tube guys landing in a real audio happy spot: 75-85db average levels, with just enough headroom (or faux headroom as it may be).  That happens to coincide with human hearing's most sensitive range, which is advantageous for peering deep into the mix, yet never brutalizes your ears with truly high spl, hence marathon listening sans fatigue," coincides with my own experiences when I owned K-horns.  The levels cited are those at which I typically listened, and needing only 30 or 40 milliwatts/channel to achieve those levels sure made it easy to use the flea-power amps.  No one believed that I was driving them with so little!  I'd sure like to see the company capitalize on the power issue by mentioning that some listeners use very low power with their speakers.  The public has no clue about this.

 

Maynard

 

But that's kind of the whole point. It really depends not only on the speaker sensitivity, it also depends on the program content, dynamic range, your personal listening level preference, for any particular kind of music, how large the room is, how absorptive it is, how many people are in the room (more absorption), etc. For me, the single digit amps were not quite enough with some music, and just couldn't cut it at all on some other stuff. But my room is a rather generous size and very well damped.

 

The bottom line (and fact of the matter) is tube amps have more distortion, noise and coloration than the best solid state amps. And now true direct digital feedback amps are exceeding the best linear analog amplifier . It's measurable. Some people like the result, some don't.

 

Musicians often use tube amps (or any particular amp/speaker combo) as part of "their sound".

 

I'm of the school that says get rid of all the noise and distortion, accuracy first. If you can do that, then you're welcome to muck it up however you please afterwards and still have a system that you know is capable of accuracy. That's the frame of reference. And the real reference is the original performance. But if you don't have any or limited experience with playing and recording live music, acoustical or amplified, your point of reference is limited to your personal preferences. If you like what you hear, great! But don't expect everyone or anyone to enjoy it as you do. It's really a rather personal thing.

[Don Richard]

I'm of the school that says get rid of all the noise and distortion, accuracy first. If you can do that, then you're welcome to muck it up however you please afterwards and still have a system that you know is capable of accuracy. That's the frame of reference. And the real reference is the original performance. But if you don't have any or limited experience with playing and recording live music, acoustical or amplified, your point of reference is limited to your personal preferences. If you like what you hear, great! But don't expect everyone or anyone to enjoy it as you do. It's really a rather personal thing.

 

This.

[Guest thesloth]

The bottom line (and fact of the matter) is tube amps have more distortion, noise and coloration than the best solid state amps.

 

I disagree.

 

Lets use operational amplifiers for example. The open loop gain is exceedingly high so feedback is used to keep gain to a usable level. Feedback increases bandwidth and lowers distortion and is what gives it the "superior" specification. You can design a tube amplifier with a lot of open loop gain and lower it with feedback too, the distortion will vanish to a very low number as well. So why don't tube designers do this? Because distortion below a certain point is basically pointless, some would even argue it is too sterile. Why have multiple stages and lots of gain just to negate it with feedback if the amplifier has low enough distortion to begin with, triodes are very linear.

[tube fanatic]

Don, it's nice to see you on here.  Regarding your comment, I'm a bit confused.  If playing your system at 1/4 watt, a 20 db peak would only require 25 watts.  Where does the 50 watt figure come in for a 13 db peak?  Also, other than full orchestral pieces, how often do we see even a 10 db peak?  Certainly not with most modern pop/rock/country stuff.  So, headroom may not be as much as a factor for many listeners.

Artto, I understand your point about getting rid of all the noise and distortion, but question whether it will make a difference in terms of the actual listening experience and pleasure (basically the old philosophy of "if it sounds good to the listener, it is good").  Referencing the original performance is only possible if one attended it, and the perception of that would vary with where one sat.  Then, there's the question of whether it is really possible to recreate an original performance in one's listening room.  Perhaps so with a small chamber ensemble, but a full orchestra in Carnegie Hall?       

And, as all expect, I agree with Sloth.  Amps should be designed so that the fewest number of bandaids have to be applied (whether tube or ss).  It's like the issue of TIM.  It's possible to minimize, or greatly reduce, that by eliminating global feedback (using a small amount of fb locally in each stage, if needed), and limiting bandwidth at the amp's input (why feed in frequencies which will only need to be filtered out before they reach the speaker).  I'm not convinced that an amp needs to have a bandwidth which goes from "dc to daylight" to sound good.  But, as with everything in audio, this is a purely personal and subjective conclusion.

Maynard  

[FloridaBoy]

Steve Deckert explains his take on why SETs sound so good on the Decware website. Basically that all instruments produce even order harmonics, except a couple of percussive instruments (like a xylophone) which produce very complex harmonics. Even order harmonics tend to reinforce the fundamental note, and odd order harmonics are detrimental to the fundamental note. SET amps also produce even order harmonics. You loose some of that with a PP, and solid state produces odd order harmonics!

 

I have no electronics training, and no musical talent and I have to rely on my ears. What I am hearing for the first time, is instruments that sound absolutely real and the notes and ensuing harmonics of each instrument sound true from attack to decay.

 

Here is the big difference between SS and tubes that I have noted: When I sat down for some critical listening with my SS hardware, I would find myself doing other things (very uninvolving). When my tubes are lit, I can't even get chores done as I find myself sitting down and enjoying music for hours on end.

 

Isn't that the point of this pursuit? Well, for me it is. Simple tube circuits and efficient speakers do it for me. 

[tube fanatic]

 

Steve Deckert explains his take on why SETs sound so good on the Decware website. Basically that all instruments produce even order harmonics, except a couple of percussive instruments (like a xylophone) which produce very complex harmonics. Even order harmonics tend to reinforce the fundamental note, and odd order harmonics are detrimental to the fundamental note. SET amps also produce even order harmonics. You loose some of that with a PP, and solid state produces odd order harmonics!

 

I have no electronics training, and no musical talent and I have to rely on my ears. What I am hearing for the first time, is instruments that sound absolutely real and the notes and ensuing harmonics of each instrument sound true from attack to decay.

 

Here is the big difference between SS and tubes that I have noted: When I sat down for some critical listening with my SS hardware, I would find myself doing other things (very uninvolving). When my tubes are lit, I can't even get chores done as I find myself sitting down and enjoying music for hours on end.

 

Isn't that the point of this pursuit? Well, for me it is. Simple tube circuits and efficient speakers do it for me. 

 

Non-technical audiophiles actually have an advantage over those with technical knowledge- they make decisions solely with their ears as Luv_sum_Horns pointed out.  And, I certainly agree that simple tube amps in combination with suitable speakers are the way to go.  I've had people tell me "that's the sound I want" too many times through the years to believe otherwise.

Maynard

[oldtimer]

Referencing the original performance is only possible if one attended it, and the perception of that would vary with where one sat. Then, there's the question of whether it is really possible to recreate an original performance in one's listening room. Perhaps so with a small chamber ensemble, but a full orchestra in Carnegie Hall?

 

Two forks in the road.  Artto's point about accuracy was in reference to the recording of the event.  Not about what you may have heard at the event crammed into a corner.  The best you can do is reproduce the recording as accurately as possible.  People with experience know what a piano or a violin etc sounds like in person.  If you go down the path of it's just not possible to reproduce the live sound down the chain then I can see where people justify screwing with everything to make it sound like they like it.  So pick your poison.  Obviously the person recording the event should make every effort possible to be true to the sound.  Search Mallette and his thoughts and experiments with recording. 

[Don Richard]

Don, it's nice to see you on here. Regarding your comment, I'm a bit confused. If playing your system at 1/4 watt, a 20 db peak would only require 25 watts. Where does the 50 watt figure come in for a 13 db peak?

 

It comes from a misplaced decimal point, lol. Should have been 5 watts, still at the upper end of the amp's linear operating range, nice catch.

 

The Dynamic Range Database identifies many non-classical works with a dynamic range in excess of 13 dB. Sometimes different issues of a recording have different dynamic ranges, usually with newer releases mastered for loudness. A person could work it another way, by choosing a version of a recording with less dynamic range to keep the sound cleaner with less efficient speakers or lower power equipment.

 

https://community.klipsch.com/index.php?/topic/143320-loudness-war-and-the-dynamic-range-dr-database-some-observations/?hl=%2Bdynamic+%2Brange+%2Bdatabase

Edited August 18, 2015 by Don Richard

[tube fanatic]

 

Don, it's nice to see you on here. Regarding your comment, I'm a bit confused. If playing your system at 1/4 watt, a 20 db peak would only require 25 watts. Where does the 50 watt figure come in for a 13 db peak?

 

It comes from a misplaced decimal point, lol. Should have been 5 watts, still at the upper end of the amp's linear operating range, nice catch.

 

The Dynamic Range Database identifies many non-classical works with a dynamic range in excess of 13 dB. Sometimes different issues of a recording have different dynamic ranges, usually with newer releases mastered for loudness. A person could work it another way, by choosing a version of a recording with less dynamic range to keep the sound cleaner with less efficient speakers or lower power equipment.

 

https://community.klipsch.com/index.php?/topic/143320-loudness-war-and-the-dynamic-range-dr-database-some-observations/?hl=%2Bdynamic+%2Brange+%2Bdatabase

 

I forgot about the DR database and glad you brought it up.  It is so easy to achieve very loud listening levels with the near-field systems that dynamic range isn't a problem for me or those who follow a similar model.  This, in spite of using what would be considered flea-power amps.  When playing selections with which I'm familiar, I'll set my listening level at the selection's loudest passage which ensures clean reproduction since the rest of the recording will require less power.

Maynard

 

Edited August 18, 2015 by tube fanatic