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Differences between tube amps and solid-state amps - How do I know which one to get?

post #1 of 44
Thread Starter 

First of all, I am pretty much completely new to the whole amplifier sector of high-fidelity audio.

 

I've seen and heard tube amps at a local meet before, but I am confused as to how they differ from the more widely-used (from a consumer's point-of-view) solid-state amplifiers.

 

Q: Why is a solid-state amp called a 'solid-state' amp?

A: ?

 

 

Q: How do they sound different? (ie. what is the 'tube sound' that people speak of?)

A: Quote:

Originally Posted by firev1
 
Tube sound can be described as warm, smooth, musical and other esoteric terms. Their soundstage are also typically wider
...
SS amps when done right, are said to be totally revealing, transparent, resolving and sometimes, a black background(low noise)

 

 

How does one know if a tube amp is needed one or not?

A: Quote:

Originally Posted by Citan
 
There really is no reason to go with a tube amp if you are looking for the highest possible fidelity
Quote:
Originally Posted by firev1
 
[tube amps] have musicality which may compensate one way or the other for recording losses
...
Generally I would consider Tube amps if I at least own a 600 ohm DT880 ,HD650, AKG Q/K70X

 

 

Q:I've read that tube amps have more distortion than a solid state amp, is that true?

A: Yes

Quote:
Originally Posted by Citan
 
Tube amps will almost always add more distortion than a decent solid state amp
Quote:
Originally Posted by firev1
 
due to the supposed combination of bad phase response(on scopes) and Total Harmonic Distortion. THD wise, they have significant levers of 2nd and 3rd harmonics concerting with 4th and 5th harmonic distortion

 

 

Q: Some vacuum tubes feature a really cool-looking blue color. Why does it produce the blue color?

A: Quote:

 

Originally Posted by firev1
 
As for the light, its caused by electron flow if I'm not wrong but some DIYers also add LEDs in the tubes

 

 

Q: Is a "Magic Eye tube" an amplifier as well? I've seen videos of these on YouTube and they look fascinating.

A: ?

 

 

Q: What are the differences between a WOT and OTL amp?

A: Quote:

 

Originally Posted by firev1
 
OTL means output transformerless which summarizes everything. WOT probably means the reverse.

 

 

 

 

I had the opportunity to try my SRH940's with a Bottlehead Crack OTL amp at the last meet. When I asked Doc B of the Bottlehead Corp. if I could try the SRH940's with the Crack amp, he said sure, but the Crack wasn't really intended for a 32 ohm headphone. Despite this, the SRH940's actually sounded quite nice with the Crack.

 

Q: Again, I'm new to amps, but what does a headphone's impedance rating mean?

A: ?

 

 

Q: What does an amp's output impedance mean?

A: ?

 

 

Q: What does the sensitivity of a headphone mean?

A: ?

 

 

Q: How do these numbers affect one's decision to purchase an amp?

A: Quote:

 

Originally Posted by firev1
 
impedance matching is VERY important with tubes
...
You run the risk of damaging either the amp or headphones when using it outside it's design conditions. That being said a good low output impedance SS amp would Shurely pair well with your Shures [which are 32 ohms]

 

 

 

Q: The Bottlehead Smack WOT amp offers switchable output impedances, what is the advantage of this?

A: See answer from previous question. Having more output impedance options probably reduces the risk of damaging headphones if you own multiple pairs with different impedances.

 

 

Q: If I own a 32 ohm impedance headphone, would it be a better option to purchase a solid state amp, or a tube amp? I really like the appearance of tube amps because they look like vintage devices, but I don't know if I really need one or not.

A: Quote:

Originally Posted by firev1
 
I suggest SS for 32 ohms
...
That being said a good low output impedance SS amp would Shurely pair well with your Shures

 

 

 

Sorry for all of the questions, but hopefully this thread can help others in the future since they are questions a newcomer might ask.

 

Thanks for any help or insight you can provide! :)


Edited by miceblue - 2/10/12 at 2:43pm
post #2 of 44

Amps should be as transparent as possible, that is, all they should do is amplify the signal.  They shouldn't sound like anything, if it does, the amp is distorting the signal.  Tube amps will almost always add more distortion than a decent solid state amp.  There really is no reason to go with a tube amp if you are looking for the highest possible fidelity.    

post #3 of 44

Well tubes just sound better than solid state.




In my opinion. Only your ears will provide that answer.

post #4 of 44

     Quote:

Originally Posted by Citan View Post

Amps should be as transparent as possible, that is, all they should do is amplify the signal.  They shouldn't sound like anything, if it does, the amp is distorting the signal.  Tube amps will almost always add more distortion than a decent solid state amp.  There really is no reason to go with a tube amp if you are looking for the highest possible fidelity.    


Actually it really depends on what you are looking for, the SS route would give you the most transparent signal chain possible, but from the mic's soundfield capturing, something was already lost from the recording and being in a studio, you will never get that 'live' sound.

 

Sure you can go the EQ the heck with a SS amp for that 'live' sound but most of us, won't know which distortion(harmonic) we would like to add. Tube amps are great in that regard, they give a warmer sound and all, you pay the price for it though. 

 

Okay now on for the definitions

 

solid-state amp - amp using transistors or opamps, generally this breaks down into 2 groups, Discrete or integrated. discrete circuits use multiple transistors and what not to make the amplifying component, usually preferred by the high end community(Vioelectric v200). Integrated circuit amps make use of opamps for the amplification like JRC5532 or OPA627.

 

Tube sound can be described as warm, smooth, musical and other esoteric terms. Their soundstage are also typically wider due to the supposed combination of bad phase response(on scopes) and Total Harmonic Distortion. THD wise, they have significant levers of 2nd and 3rd harmonics concerting with 4th and 5th harmonic distortion to give that nice full sound.

 

In comparision, SS amps when done right, are said to be totally revealing, transparent, resolving and sometimes, a black background(low noise). However, maybe boring to some as the recording mic itself losses some of the delay, phase/ blah blah of the original singer. Thus many tend to compensate for it by using extensive EQ or preferably tube amps. SS amps are also relatively big on measurements and many of the high end amps measure typically well and also validated in hearing test(most important).

 

For the next question of SS vs Tube, its generally a preference and I prefer SS done right. I still like tubes and would like to build a Crack w Speedball sometime.

 

Anyways, its answered above, tubes generally have lots more distortion but have musicality which may compensate one way or the other for recording losses. Its more of a matter of preference, I prefer SS because I mix sometimes and thus need SS amp's accuracy. 

 

As for the light, its caused by electron flow if I'm not wrong but some DIYers also add LEDs in the tubes, looks lovely in the dark no?

 

I can't answer the next few questions.

 

OTL means output transformerless which summarizes everything. WOT probably means the reverse.

 

I don't have much experience in tube but impedance matching is VERY important with tubes, I suggest SS for 32 ohms. You run the risk of damaging either the amp or headphones when using it outside it's design conditions. That being said a good low output impedance SS amp would Shurely pair well with your Shures eg. Epiphany Acoustics Objective 2, Fiio E11, CmoyBB. With your headphones I would generally go with these as the Shures would benefit little from high power($$$) amping.

 

Generally I would consider Tube amps if I at least own a 600 ohm DT880 ,HD650, AKG Q/K70X


Edited by firev1 - 12/3/12 at 6:27pm
post #5 of 44
Quote:
Originally Posted by Paganini Alfredo View Post

Well tubes just sound better than solid state.
In my opinion. Only your ears will provide that answer.

Well, that's exactly the problem. It's not supposed to "improve"/change sound. See #2.

Quote:
Originally Posted by firev1 View Post

Quote:
Actually it really depends on what you are looking for, the SS route would give you the most transparent signal chain possible, but from the mic's soundfield capturing, something was already lost from the recording and being in a studio, you will never get that 'live' sound.
I don't know any serious engineer that listens with headphones connected to a tube amp in the studio.
Edited by xnor - 2/10/12 at 11:07am
post #6 of 44
Thread Starter 
Quote:
Originally Posted by Citan View Post

Amps should be as transparent as possible, that is, all they should do is amplify the signal.  They shouldn't sound like anything, if it does, the amp is distorting the signal.  Tube amps will almost always add more distortion than a decent solid state amp.  There really is no reason to go with a tube amp if you are looking for the highest possible fidelity.    

 


Quote:
Originally Posted by firev1 View Post

Actually it really depends on what you are looking for, the SS route would give you the most transparent signal chain possible, but from the mic's soundfield capturing, something was already lost from the recording and being in a studio, you will never get that 'live' sound.

 

Sure you can go the EQ the heck with a SS amp for that 'live' sound but most of us, won't know which distortion(harmonic) we would like to add. Tube amps are great in that regard, they give a warmer sound and all, you pay the price for it though. 

 

Okay now on for the definitions

 

solid-state amp - amp using transistors or opamps, generally this breaks down into 2 groups, Discreet or integrated. discreet circuits use multiple transistors and what not to make the amplifying component, usually preferred by the high end community(Vioelectric v200). Integrated circuit amps make use of opamps for the amplification like JRC5532 or OPA627.

 

 

 

 

 

Tube sound can be described as warm, smooth, musical and other esoteric terms. Their soundstage are also typically wider due to the supposed combination of bad phase response(on scopes) and Total Harmonic Distortion. THD wise, they have significant levers of 2nd and 3rd harmonics concerting with 4th and 5th harmonic distortion to give that nice full sound.

 

In comparision, SS amps when done right, are said to be totally revealing, transparent, resolving and sometimes, a black background(low noise). However, maybe boring to some as the recording mic itself losses some of the delay, phase/ blah blah of the original singer. Thus many tend to compensate for it by using extensive EQ or preferably tube amps. SS amps are also relatively big on measurements and many of the high end amps measure typically well and also validated in hearing test(most important).

 

For the next question of SS vs Tube, its generally a preference and I prefer SS done right. I still like tubes and would like to build a Crack w Speedball sometime.

 

Anyways, its answered above, tubes generally have lots more distortion but have musicality which may compensate one way or the other for recording losses. Its more of a matter of preference, I prefer SS because I mix sometimes and thus need SS amp's accuracy. 

 

As for the light, its caused by electron flow if I'm not wrong but some DIYers also add LEDs in the tubes, looks lovely in the dark no? It sure does look really neat! :D

 

I can't answer the next few questions.

 

OTL means output transformerless which summarizes everything. WOT probably means the reverse.

 

I don't have much experience in tube but impedance matching is VERY important with tubes, I suggest SS for 32 ohms. You run the risk of damaging either the amp or headphones when using it outside it's design conditions. That being said a good low output impedance SS amp would Shurely pair well with your Shures eg. Epiphany Acoustics Objective 2, Fiio E11, CmoyBB. With your headphones I would generally go with these as the Shures would benefit little from high power($$$) amping.

 

Generally I would consider Tube amps if I at least own a 600 ohm DT880 ,HD650, AKG Q/K70X

 

 

 

 

Thanks for your replies! That really helps a lot. 
 

 

post #7 of 44

    Quote:

Originally Posted by xnor View Post

I don't know any serious engineer that listens with headphones connected to a tube amp in the studio.


 

You misinterpreted me, I never said that tube specifically improves/gives an accurate sound, in fact I said the reverse. I just said that many fellow Head-Fier's or Hi-Fiers tend to go for the 'live' sound. But ultimately, what was the music recorded by? Yes, a mic. Will the recording ever take into account human hearing? Probably, but even so, the acoustics of the studio is heck different from a live and even in live recordings, mics tend to pick up the resonances that will feel out of place. Thus some go for Tube amps as it is EASIER to compensate with distortion than EQing/DSP with SS amps with high end audio. Alternatively they are just trying to enjoy the music the way they feel best. Will it be accurate, neutral? Sure as hell no. But compared to the SS system, will it sound more 'live'? Most probably. That being said, as someone who helps do mixing sometimes, I do appreciate solid states a lot more for their accuracy. Everyone plays with audio in different ways and there are no specific or 1 way to enjoy music.

 

Actually if you read the diyaudio newsletter, it will summarise everything I said since I do quote parts from it.

 

Anyways time to answer more questions, I may be wrong feel free to correct me. Most of it is a summary of previously written material.

 

On headphone impedance- The impedance(Z) rating on a headphone that determines electrical damping which in turn can correlate to mechanical resonances and power. Low Z typically means more current flow needed rather than voltage while High Z means higher output voltage is needed. Its more of a energy delivery mode

 

Output impedance of a amp- its the Z of a amp, typically tube amps have higher Z than SS. SS amps are best 0 ohm or near 0 but some manufacturers amps have large Z as a crude form of stabilising the amp.

 

Sensitivity- Amount of power needed for a given sound pressure level(SPL)

 

Why is impedance and sensitivity such a big deal? 

Basically they determine a few things the most important is of course, volume levels. This article and its source material provides the picture. Of course I'm going to summarise it. Note that with SS amps of high Z and tube amps, these numbers are usually almost worthless, which will be explained.

 

P = (Vmax * Vmax) / Headphone Impedance

Gives the peak power at a given headphone impedance for the voltage

dBSPL = Sensitivity(of headphone) in dB/mW + 10 * LOG ( Pmax of amp in mW)

this gives the peak SPL of a certain headphone that can be reached given the maximum power of an amp.

 

Of course why else knowing these are important? Its also because they will also determine what TYPE of amp to but. With high impedance phones with high sensitivity ala Beyerdynamic headphones, any mid range amp will do as they are easier to drive. Then the question arrives, which amps more difficult to find/pair with?

 

There are 2 types,

 

Those built for low impedance, very high sensitivity/Balanced Armature headphones/IEMs because one they typical require a very low noise floor(SNR) and require 0 ohm output impedance to sound good. These do not require much power though. Examples are the Sony XBA-4, Denon headphones and many other BA driver IEMs rated 16- 32 ohm. If of interest the ER-4s does not fall into the category despite being a BA due to its high impedance.

 

Built for low impedance, low sensitivity, which not only means that it is ridiculously hard to drive, also that typical tube amps with their low current reserves just don't stand a chance. Examples of such are Hifiman orthos especially HE-6, AKG K/Q70X.

 

So what do the more expensive amps have in common? Usually lower impedance values, higher current values and much lower noise floors. For those types mentioned SS is preferred though there are some tube amps which do the job(very expensive).

 

But why lower impedance headphones are harder to pair? It's because of electrical damping factor, to reduce amp distortion and increase linearity, reduce mechanical resonance of the headphone driver, lower amp output impedances are needed to pair with low impedance amps. This Benchmark article explains it all. An example of such an amp is also the highly acclaimed Violectric V200 amp which has a output impedance of a fantastic 0.06ohms. 

 

Violectric also explains it in detail so I don't have to,

Why is a high damping factor essential ?



When actuated, electro-dynamic systems respond with a counterforce. When the voice coil of a headphone has been displaced by the signal, an (error)-current will be induced when it swings back to its initial position. This current must be suppressed as far as possible, which is effected best if the amplifier's output impedance is the lowest possible. The damping factor describes nothing but the ratio between output impedance of an amplifier and a given load. Since there is no known technical specifications, we define the load (voice coil impedance) as 50 ohms. This results in an output impedance of <0.06 ohms in case of the HPA V200.

 

Damping factor is basically: Zin/Zout Note that 50ohms is also a typical value of an Ortho driver. According to nwavguy, a damping factor of at least 8 is desirable.


Edited by firev1 - 2/10/12 at 9:00pm
post #8 of 44
All of that is fine and dandy but I still don't get why a tube amp should contribute to make the sound more 'live' instead of 'sugarcoated'. If there were resonances in the concert hall or wherever and the mic picked them up then it's most probably on the recording too and especially with headphones, which don't have room acoustics, I'd like to hear those resonances instead of masking them with distortion, noise or whatnot.

Btw, if you have an SS amp and ever should feel the need for high output impedance / low damping factor simply add two resistors in series with the headphones.
post #9 of 44
Quote:
Originally Posted by firev1 View Post

In comparision, SS amps when done right, are said to be totally revealing, transparent, resolving and sometimes, a black background (low noise).


Exactly. This is by far the most important reason I use solid state. No black background = not hi-fi, in my opinion. 

Stunning to read how many well-regarded tube amps around here are noisy, when no music is playing.

 

 

 

 

Quote:
Generally I would consider Tube amps if I at least own a 600 ohm DT880 ,HD650, AKG Q/K70X

 

Hm, I don't.

I'm using SS amps for both my DT990/600 and T1 and they sound sweet biggrin.gif

post #10 of 44
Quote:
Originally Posted by xnor View Post

All of that is fine and dandy but I still don't get why a tube amp should contribute to make the sound more 'live' instead of 'sugarcoated'. If there were resonances in the concert hall or wherever and the mic picked them up then it's most probably on the recording too and especially with headphones, which don't have room acoustics, I'd like to hear those resonances instead of masking them with distortion, noise or whatnot.
Btw, if you have an SS amp and ever should feel the need for high output impedance / low damping factor simply add two resistors in series with the headphones.


Well objectively speaking tubes are also more than just high Z and low damping factor. The interesting thing is how their harmonic distortions concert with each other which is also one of the reasons they make good musical instruments(guitar amps). 'Live' or 'sugarcoated' it is ultimately up to the listener to choose where and how he would like to 'compensate' for mic losses and ultimately, whether the way he chose is worth it.

 

As for the high Z mod, I was aware of that early but as I have said, its more than just the distortion, is how and where distortion. I love the black SS background though but than again, I have not much experience with tubes, it has always been integrated receivers/SS headamps for me. 

post #11 of 44
Thread Starter 

Wow, thanks for the explanations! I'll have to read through them more carefully when I get the time. I've been pretty busy with school lately.

post #12 of 44

I've set two files simulate SS amp & tube amp.

Here's the thread:

http://www.head-fi.org/t/596966/could-you-here-the-difference

 

I didn't state which was which, because I want to know under blind test situation which would have more preferred.

 

 

But it still has not enough sample currently.

 

Perhaps you guys could help :).

post #13 of 44
Thread Starter 
Quote:
Originally Posted by killkli View Post

I've set two files simulate SS amp & tube amp.

Here's the thread:

http://www.head-fi.org/t/596966/could-you-here-the-difference

 

I didn't state which was which, because I want to know under blind test situation which would have more preferred.

 

 

But it still has not enough sample currently.

 

Perhaps you guys could help :).


Ooh, that's a cool test. I'll be sure to cast my vote when I get the chance. :)

 

post #14 of 44

Q: Why is a solid-state amp called a 'solid-state' amp?

 

Solid-State is a term used in electronics to describe electronics made entirely from solid materials, apposed to vacume's such as tube amps

http://en.wikipedia.org/wiki/Solid-state_(electronics)

post #15 of 44
Tube amplifiers provide additional sensory stimuli that reinforce the suggestion of a certain quality.  They generate heat, which one can feel, so a "warm" sound is expected.  They generate warm orange light, which also  reinforces the "warm" expectation.  Certain power tubes may also produce a faint etherial blue haze inside the glass, though these tubes are not typically used in headphone amps. Tubes also generate thermal noise due to their high operating temperatures and relatively high operating impedances, which may be interpreted as ambience, space, air, or other descriptors.  They are also well known as older technology, so there's a pseudo-nostalgic quality, which is often coupled with a general feeling of well-being and happiness.  Tubes are also strongly reputed to be more "musical", and more esoteric due to higher general cost.  That reputation provides the quality of elitism, which can reinforce a positive emotional reaction.  There's a lot of positive sensory and psychological reinforcement available from tube amps to support a positive sonic impression.
 
 
Solid state amps generate very little heat, and have really nothing to look at.  The also usually generate less noise, many being audibly dead silent.  They are comparatively low cost.  They provide very little in the way of sensory stimulus to support positive emotional responses surrounding a sonic impression.  Solid state amplifiers did pass through a brief period in their evolution where the did in fact sound quite inferior, likely because early transistor circuits were designed by old tube engineers who had difficulty embracing the concepts of current gain and low impedances.  Once those principles were  understood and device performance improved, the performance of solid state amplifiers surpassed tubes.  But the negative reputation was not so easily shaken off, and persists today.  Solid state amps offer very little in the way of sensory and psychological reinforcement of a positive sonic impression.  Their sonic impressions stand very much on their own.
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