Tube amps! Why use them?

madmax

Originally posted by nascarmann


Man......what a site that must be.....

I'll agree with that one!

I only have a Marshall tube head because when I was looking at guitar equipment (which I knew absolutely nothing about) one of my friends told me this was a cool one to have. I must agree because the tone is awesome. I found one on ebay for less than most of the SS ones in the stores so I bought it. I still can't play but maybe some day. No, I don't deserve a tube head either. After getting into it I finally realized that a much cheaper combo amp would have been better suited to me. My friend was talking from his own experience (he plays professionally) and didn't mean for me to actually get one. I'm not sorry though because you can always re-sell the stuff if it doesn't work out. We took his and added a rectifier tube to it in place of the diodes. This was an awesome mod and I plan on doing it to mine just for the hell of it. It adds a little sag to the sound like the older Marshalls had.

This is what got me into the tube thing: I hooked the marshall up to one of the SDA's (playing quietly of course) and heard sounds I couldn't believe coming out. I just figured there was something to it. That is why I tried one of the Jolida stereo amps. This was absolutely the best stereo upgrade I have made in the past 10 years! Tubes are awesome!

I was thinking this thread was getting long enough to start annoying people.
madmax

CrazyHead

This was a good thread to catch up on...

Here's my take, I'll try to put some of the tube misunderstandings and mysticisms to bed here.

I used to feel that tubes were a waste of time because they add "distortion", were so expensive, and were just rich person' play things. Plus, they are old tech -- how can they be any good? So, I lived with various solid state amplifiers while I continuously read things about tubes, etc.

Then, about one year ago, I found a used JoLida 502A sitting on the floor of a local hi-fi shop. I saw the tubes and noticed it was in the "used" pile of gear, just sitting there collecting dust. I asked how much it was, I expected it to run at least a grand or two. Later I found out that the 502 originally sold for around $1200 when it was new. The price tag on the used one was an astonishing $280. Unheard of -- even on eBay these things regularly go for $700-$800. So I took it home and gave it a listen for a demo.

I am glad I did, because I immediately liked the sound. It was somehow cleaner and more robust.

I've modded my amp, replaced some caps, a handful of resistors, upgraded the wiring and such, and of course there's the joy of tube rolling (experimenting with different makes and vintage of tubes to change the sound). None of the tube changes are like EQ'ing things different. It's hard to explain, really... it's more of an aural type of change. Subtle ways in how the sounds are changed, their weight, the air between instruments, etc.

Tubes and solid-state equipment produce different types of distortion. Solid-state gear produces mostly what is known as odd-order harmonics. Tube gear, on the other hand, produces more of what is known as even-order harmonics. The details of which are fairly interesting and of an entirely different thread. But, it is certain that the human ear prefers even-ordered harmonics (even meaning that each multiple of the fundamental lands within our tuning scale, odd-ordered does not).

The general saying is that solid state can be harder to listen to than tube equipment due to this very issue. Harder in that it becomes more fatiguing, much quicker. Expensive SS gear uses lots of negative feedback to mask the distortion. Different tube circuits use negative feedback to reduce distortion as well. However, both amp types leave their own sonic signature and you can tell the difference.

The other issue revolves around clipping. A transistor is, more or less, a switch. It's on or off. When you reach a peak, and the transistor can go no further, it will simply shut off and clip the signal. This can happen at virtually any time as you increase the power demands on the amp. This clipping will result in added distortion, hardness to the sound, or an edgy feeling. It will become harder to listen to. Tubes, conversely, operate as a "valve" (hence the term fondly used in Europe, "valve amps"). A tube will distort, but not clip from what I understand. It will reach a peak but it will never simply flat-line at the extremes and burn the sound up. Tubes gracefully distort. The valve comparison comes from the idea of turning a valve, the more you turn the more current flows.

As for why tube gear generally sounds finer and more detailed... I believe this can be summed up very easily. Tube amps are about a thousand times simpler to design than a solid-state amp. If you've ever seen the guts of a tube amp, you'll know what I mean. A handful of resistors, caps, power transformers, and tubes are just about all it takes. You can build one yourself in an afternoon. Now, open up your big Marantz or Harman/Kardon receiver. You'll see boards and boards and hundreds of parts, caps, resistors, transistors, little traces, ribbon cables for controls, logic boards, ICs, DACs, the works! All sorts of things for that poor little audio signal to run through. Crosstalk and all! Yikes! Take a look at the RCA jacks in those receivers... from the jack right into a PCB trace that probably runs for 50 feet through all kinds of components before it finally hits the power.

So, you have a tube amp with about 50 pieces total. Then you have a solid-state amp with about 500 pieces total. Which is going to take the line-level input to the power in less time with less obstruction?

This, combined with the more even-ordered distortion that a tube amp provides, yields unbelievably good sound... the type of sound that makes everything sound more real, far cleaner, and more involving!

Like others have said... I find it hard to listen to solid-state amps anymore. Even the high-buck audiophile ones, as clean and analytical as they are, still sound edgy to me. Something is just "not quite right" about them.

Then there are the hybrid amps... the ones that use a tube pre-stage and solid-state power amplification. These are interesting beasts because they lace the sound with a little of both types of distortion. You get the bass control of solid state with some of the euphonics of tubes. A hybrid is also a simple circuit (not as simple as pure tube, however) and thus less signal obfuscation. They're also much less expensive to produce (you can find JoLida hybrids for around $350). A lot of people just dig the heck out of hybrid amps and swear by them. I have not heard one, personally, but I am sure they are as good as they claim!

So that's everything in a nutshell. I hope I've helped clear a few things up for some of you regarding the non-technical side of tubes amps. If I am wrong with anything, feel free to correct me. This is just the summation of what I've read over the last year.

Good listening, everone!

-crazyhead-

gidrah

Great read Crazyhead! Long time no see.

I've been contemplating a pair of Antique Sound Lab Wave 8s for a time now. I just need some more efficient speakers first.

madmax

Nothing wrong with any of that!
I also never thought of tubes as an upgrade. The first Jolida I got was going for $355. I bought it thinking it was a toy which would make for a cool discussion piece in my bedroom system so the waste of money was reasonable. That ended up costing me a lot because after a few months I realized these super powered solid state amps only annoyed me when I listened to them. It wasn't long until they were sitting there gathering dust and several new tube sets took their place. Lets face it, a $355 amp that replaced two $1400 mono blocks aint a bad deal! Now I have 3 used Jolida amps and two Manley mono blocks. They are cool to gather around when it gets cold outside as well!
madmax

HBombToo

Originally posted by CrazyHead
This was a good thread to catch up on...
Tubes and solid-state equipment produce different types of distortion. Solid-state gear produces mostly what is known as odd-order harmonics. Tube gear, on the other hand, produces more of what is known as even-order harmonics. The details of which are fairly interesting and of an entirely different thread. But, it is certain that the human ear prefers even-ordered harmonics (even meaning that each multiple of the fundamental lands within our tuning scale, odd-ordered does not).
-crazyhead-

I had totally forgot about this thread and am glad to see you revived it crazyhead. Thanks!

IMO this is the perfect thread to go a little deaper into even and odd harmonics and would really enjoy seeing a discussion because I would learn quite a bit. Whether or not in this thread please expand on this most interesting topic.

Regards
HBomb:)

madmax

I have no idea what causes a tube to output mostly even order distortion and transistors to output mostly odd order harmonics. That would be a good place to start. Maybe something to do with negative feedback being applied?
madmax

HBombToo

Hmmm... I guess I'm way off because I was thinking it may have something to do with the amplifier class.

Do Class ab amps suffer from even harmonics?

HBomb

madmax

Now I'm just talking here but I think class is not much of an issue BECAUSE all of the SS units and tube units I'm familiar with are all push pull (class AB). I'm wondering if it has something to do with voltage source rather than current source. (tubes are voltage source, I think? I'm not sure) Lets see, you can leave a ss amp with an open ouput but cannot short the output. Tube amps you can short the outputs but cannot leave them open without damage. So far I only have a bunch of useless facts. Someone should give us a hand here!
madmax

CrazyHead

Originally posted by HBombToo
Hmmm... I guess I'm way off because I was thinking it may have something to do with the amplifier class.

Do Class ab amps suffer from even harmonics?

HBomb

I absolutely would not say "suffer" is right at all! Even-ordered harmonic distortion is far, far more pleasing to the ear than odd-ordered distortion.

Let's face it, all amps distort virtually all the time. Distortion does not equal clipping! We can talk about temporality, resonance, etc. but it all comes down to the fact that there is always distortion present in an amplifier. Some have more at given volume levels than other, etc. That's why the infamous "THD" ratings should be taken with a grain of salt.

There are tube amps that have THD ratings that rival many solid state amplifiers. But what are they guaging that off of? What power level? Peak? I should think not.

For example, JoLida advertises the 502/302 series amps as having "less than 1% distortion at 50W, 28Hz - 15kHz". Okay, so if you read JUST THD numbers, you see an amp that introduces a near whopping 1% THD! Holy ****! But, as myself and madmax know, these amps sound blisteringly clean and refined. Madmax claims to have replaced $1400 monoblocks with a sub-$1000 JoLida integreated tube amp. Those monoblocks probably advertised 0.002% THD. Of course, did they say what the output was? 0.002% THD at idle current is probably absolutely reasonable. JoLida rated 1% at 50W output for the 302 -- that's full power for that amp, boys and girls! So, ignore THD figures because they don't mean jack.

To get back on track, some distortion is always inevitable. It's the type of distortion that an amplifier type inherently produces that paints the big picture in terms of listenability.

Even-ordered is what we much prefer to hear, this is why tube amps generally sound superior to their solid-state brothers.

-crazyhead-

TroyD

I am finding this thread incredibly illuminating, thanks guys.

If you could dumb it down for me a little, could someone explain the difference in even and odd ordered harmonics?


BDT

HBombToo

agreed BDT.

TroyD

Just a quick commentary, not wanting to derail this train, but it's kind of funny that in the 2 channel forum, you've got some discussions that are pretty cerebral on analog and tube gear. In the other forums we are screaming "EFF YOU, my dick is bigger than yours"

Just an observation

CrazyHead

Originally posted by TroyD
I am finding this thread incredibly illuminating, thanks guys.

If you could dumb it down for me a little, could someone explain the difference in even and odd ordered harmonics?


BDT

Right, here's some info I snagged from Deja (now Google Groups) about this very subject:

At least, assuming that "odd harmonic" and "even harmonic" refers to those
signals which are odd and even multiples, respectively, of the original
("fundamental") frequency. Suppose the fundamental is a 440 Hz "A". The
first two even multiples occur at 880 Hz and 1760 Hz - each "A" in
successive octaves. 6X the fundamental is 2640 Hz, very close to an
E (which is a fifth up from the 1760 Hz A6).

Now look at the odd multiples:

1X = 440 Hz (A4)
3X = 1320 Hz (close to E6)
5X = 2200 Hz (roughly a C sharp - ooops!)
7X = 3080 Hz (not quite an F sharp - oops again!)

And now, an even better thing... sonic samples for you to download and compare! This page has samples comparing 0.1%, 1%, 10%, and 30% THD across 2nd, 3rd, 4th, and 5th order harmonics.

http://www.pcabx.com/technical/nonlinear/index.htm

Myself, I cannot accurate discern between the original and 0.1% on my laptop with Grado SR-125 headphones. However, 10% is quite easy. Notice how the odd ordered harmonic distortion (3rd and 5th) make the music sound sort of edgy, with information loss in certain octaves. Compare to the even ordered (2nd and 4th) distortion which sounds reasonable, all the way to 30% (albeit very muddy and clearly problematic at 30%).


-crazyhead-

CrazyHead

Originally posted by TroyD
Just a quick commentary, not wanting to derail this train, but it's kind of funny that in the 2 channel forum, you've got some discussions that are pretty cerebral on analog and tube gear. In the other forums we are screaming "EFF YOU, my dick is bigger than yours"

Just an observation

Ahh, we wont derail anything.

I rarely read many other posts in the other areas of this forum so I cannot comment on the statements of others. But I am surprised you hear of that kind of behavior here. This is one of the better forums on-line, even if it does require a Polk serial number to join up.

2-channel people seem to be a different breed. I used to be into HT heavily. That's how I started. I had a big 15-inch sub, huge Polk tower speakers, big 5.1 receiver (big watts and tons of RCA jacks in back). Yeah, I was the king of the surround sound hill. Then I was given the "deal of the century" (according to, believe it or not, Mike Allen (sp?), the owner and amp designer of JoLida who knows my saga) with my $280 Jo 502A. Everything fell apart in my HT after that. I shed the sub, shed the surrounds, shed the receiver, lost the big towers and replaced them with a svelte pair of LSi9's. The sound is better, the music is more alive, movies are just as satisfying, and the tubes are way sexier to look at when the ladies are over (huge banks of green, orange, and red LEDs are not nearly as tactile, romantic, and involving as the deep orange glow of the fillaments inside the sealed glass tubes).

The amp is always a conversation starter as well. People invariably end up asking questions. Then they get their CD's from their car. Then they start ooh'ing and ahh'ing. Later we end up on eBay looking at amps for their own livingrooms.

-crazyhead-

madmax

Here is a less technical way to look at even and odd distortion. Correct me if I'm wrong.

Even order distortion is like playing two keys on a piano such as a "C" and an "E". Sounds very nice. You can play a "G" as well and it sounds great. Even if you intended to play a "C" only but accidentally played a "E" as well probably no one would notice it.

Odd order distortion is like playing a "C" at the same time you play a "D". (the key next to it). No matter how loud everything else is you will hear that the "C" and "D" were accidentally played at the same time because it sounds horible.

madmax

HBombToo

I really wish I knew how to read music... I'm an idiot when it comes to that stuff and should have got into it as a child but I was too head strong.

I had the oppertunity and let it slide. Shame on me.
I know numbers though and its all I have ta go on. So I'll keep pushing.

Thanks
HBomb

TroyD

Your a pretty intelligent dude, reading music is NOT that difficult.

BDT

HBombToo

Thanks BDT. Perhaps I'll give it a shot.
A guy I work with is very good at music... writes his own, has a band and you should see his recording studio. Pile of cash tied up in some really cool stuff. Maybe old dogs can learn new tricks? We'll see.

HBomb