solid state vs. tubes. Pros and Cons

[emack27]

I've listened to solid state my whole life and was just wondering what are the characteristics of tube amps. Do they sound bright or smooth compared to solid state? What type of speakers sound good with tube amps high effiency or low effiency?

[JoeE SP9]

To my ears there is more there there with tubes. I use solid state only for bass frequencies below 80hz. I have tried various SS amps and preamps over the years and always return to tubes.

[emack27]

OK so would it be fair to say that high efficient speakers sound good with tubes and low efficient speakers sound good with SS?

[jrhymeammo]

Are you considering a tube amp? How big is your room? I believe your speakers have efficency rate of 88-90dbs. As long as you str noy considering a tube amp with 6-10watt output you should be okay.

[emack27]

No, I'm not considering a tube amp. I like my amp just fine. I was just wondering.
BTW, Do you know when solid state amps were started to be manufactured over tubes?

[dean_martin]

OK so would it be fair to say that high efficient speakers sound good with tubes and low efficient speakers sound good with SS?

Actually, there's not a bright line rule on that, but it is more likely that high efficiency speakers will work better with lower watt tube amps. But there are some solid state designs from makers like Pass Labs and Sugden that run totally in class A that work better with high efficiency speakers. These amps are usually rated at 25-30 watts per channel.

When it comes to tubes, I think economics has more to do with this than anything else. You can get a 100wpc solid state amp for around $300 - 500USD that can drive something like a Dynaudio speaker (4 ohm, 84dB) while a 100wpc tube amp that can drive the same speaker might cost 10x more. Most entry-level tube designs are rated at 25-40wpc and need to drive a more efficient speaker. There are big bucks tube amps that can drive just about anything.

Then there are the extreme examples of low powered tube amps such as SET, 300B, and 845 designs that are rated at about 2.5 to 15 wpc. They make really high efficiency speakers for these that are often single driver designs in the 97dB to over 100dB efficiency range.

So, it usually works out the way you stated it, but it's not a rule. I think the rule can be stated more generally, i.e., lower powered amps (whether tube or solid state) sound/work better with more efficient speakers.

In describing sound characteristics I would have to say in my limited experience that tubes do sound smoother and I believe they sound more natural. You don't have to give up detail with tubes. In fact, I've been trying different tubes in my amp recently and I found a pair that really opens up the treble adding more detail and "air" in the high frequencies. Without balance such as midrange detail and bass weight, this would sound "bright". I'm trying to decide whether these tubes have too much treble emphasis but I don't think they are fatiguing. With my old solid state gear, music with lots of treble info like strings would become fatiguing. The best thing to do would be to take some of your favorite recordings to a dealer that carries tube equipment and audition. Interestingly, it seemed that until recently some tube amp manufacturers were trying to make their tube gear sound more like solid state. Find a dealer that carries brands that have the more traditional tube sound like Conrad-Johnson, Cary and Jolida. Heck, if you were going to get a tube amp that sounded like solid state you might as well get a solid state amp from Krell or Bryston.

Anyhow, I got my first home audio tube amp in November of last year. I've enjoyed the music, but I've also had fun learning about tube amps and trying different tubes.

[JoeE SP9]

OK so would it be fair to say that high efficient speakers sound good with tubes and low efficient speakers sound good with SS?

The only answer to that is no. You really have to give the different types a listen in your own room. You might like tubes with your speakers and you might not. I like tubes no matter what kind of speakers are in use.

[theaudiohobby]

I've listened to solid state my whole life and was just wondering what are the characteristics of tube amps. Do they sound bright or smooth compared to solid state? What type of speakers sound good with tube amps high effiency or low effiency?

I will be contrarian here, and say that tubes SS divide is more an expression of preference that any inherent sound qualities per se. For example, the last tube preamp that I had in my system sounded opaque and the last SET power amplifier that I heard at length was brighter sounding than my current SS amplifier. So far, I have heard a ground total of zero tube amplfiers that I prefer to my current SS amplifier.

Saying that, tube amplifiers especially those that are of the SET variety tend to be low powered <20Wch, therefore speakers with sensitivity >90dB/m are best. Also many especially those of the no feedback variety tend to have high output impedance, therefore a speaker with a resonably high impedance ~8ohms are advised, This is general rule of thumb as there are exceptions to rule, It not unheard of for folks to like specific speaker-amp interactions.

[ruadmaa]

BTW, Do you know when solid state amps were started to be manufactured over tubes?[/QUOTE]

It was in the late 50's early 60's. Actually the process tooks quite some time. At first many "hybrid" amps/tape recorders/record players etc. began to appear. These were devices that had both transistors and tubes. As transistor technology became better, more and more tubes were replaced with transistors until finally, there were no tubes at all. I had several reel to reel tape recorders that had both tubes and transistors. I also have a 1959 Seeberg jukebox that has one or two transistors and the balance tubes.

[E-Stat]

I've listened to solid state my whole life and was just wondering what are the characteristics of tube amps.

It would require a lengthy essay to fully answer your question as this topic has raged on for decades. Each has its own set of advantages and disadvantages. I confess my preference has changed as I have gotten older, (hopefully) wiser, and my musical tastes have evolved. Simply put, tubes and solid state differ in the way they distort the signal. The human auditory system also comes into play because we have different sensitivities to different kinds of distortion. Quantity alone is not a good measure of musical faithfulness. It has been proven long ago that the even order harmonic distortion produced by tube amps is far less audible than the higher order, odd harmonics generated by solid state amps. Tube amps distort right in the audible blind spot so to speak. Another problem with the metrics is that they are measured with steady state signals, not dynamic musical content.

When I started my journey back in the seventies, engineers found a way to reduce the amount of measured distortion by several orders of magnitude of what was found with tube amps. While a typical tube amp had one to two percent harmonic distortion, SS designs incorporating high levels of negative feedback got that down to 0.001%. Better, right? Not exactly. Under analysis, the concept of NF is the notion of changing what has already happened. Corrective feedback works well in moderation, but the extreme amounts used back then resulted in brutally hard sounding amps. Witness the early Crown designs (I owned one myself when I was 17). The IC-150 preamp was notorious for horrible sound despite wonderful measurements. Over time, engineers learned and the best of todays SS crop uses very minimal or no feedback whatsoever. The Pass Labs XA, GamuT, ASR Emitter, Parasound JC-1, Edge Signature, Dartzeel are just a few of many excellent examples.

In my early twenties, I purchased a Threshold Stasis amp highly regarded for its excellent bass and high end response. It used no overall NF. I valued tight, low end response and crystal clear extended high end. Limitations? It did not offer the same best-of-class midrange response of the vaunted Audio Research D-150 of that day. Huh? How do you NOT get good midrange? Reviewer Harry Pearson of The Absolute Sound stated decades ago that getting the midrange right was key to musical faithfulness. It took me nearly thirty years to fully understand what he meant. That is where tubes excel. Ultimately, your choice will be based upon not only factors of cost and practicality (where tubes are most unfriendly), but musical preferences. Today I use female voice or symphonic music for ultimate evaluations. If the amp cannot float a voice or allow me hear all the nuances of stringed and brass instruments, then I am not interested.

I have had the good fortune of knowing some reviewers such as John Cooledge and Harry Pearson of The Absolute Sound since 1976. That has afforded me both the unique exposure to equipment I would have never otherwise heard and benefitted from these highly knowledgeable in music mentors. I bought my current tube amps shortly after hearing their big brothers on HP's incredible system. You do not necessarily have to compromise power in tube amps as the VTL Wotans offer 600 watts in triode and 1250 watts tetrode. Albeit at a price. My more modest MB-450s put out 200 watts triode and 450 in tetrode. They get the emotional behind the music right. That is what is most important to me. Cost no object, I would have a pair of VTL Sigfrieds in a heartbeat.

IWhat type of speakers sound good with tube amps high effiency or low effiency?

Tube amps do not offer the high damping factors required by quite frankly, most speakers. As a result, the bass response is less tight and the frequency response can vary. Low powered tube amps are a great match for high efficiency horn speakers. High powered flavors excel with my full range electrostats which are naturally high impedance drivers.

Summation: solid state clearly provides more bang for your buck and the gap between the two has narrowed. I would be quite happy for example with the ASR Emitter amp and its battery powered four chassis flotilla. There is still, however, a magic with tubes that most solid state amps are unable to duplicate. You can do that to a great extent by using a tube preamp or by using front end components with tube line stages. With my vintage system, I use a tube output Manley DAC with the Pioneer PD-54 CD transport driving the Stasis directly (no preamp) into double New Advent speakers. While the Advents clearly benefit from the control of the SS amp, the tube line stage provides much of the tube magic.

rw

[JoeE SP9]

Nice way of putting it E-Stat. Tubes do get that all important midrange right. I have tried SS many times and I always come back to tubes for the midrange magic.

[Mike Anderson]

I really love super-tight, highly controlled bass. I like my integrated amp w/tube preamp and SS power section. Seems to offer the best of both worlds.

Someday, when I have the scratch, I might check out a pair of Manley 250 or 500 monoblocks to see what the tubes can do, but for now I'm very happy with the hybrid arrangement.

[JoeE SP9]

I wonder if the simpler circuits of tube amps contribute to that glorious sound. Could this be a case of "less is more"? Some of the better sounding SS gear I've heard has been Nelson Pass' single ended SS gear. That stuff is truly minimilist as far as SS circuitry goes.

[theaudiohobby]

It has been proven long ago that the even order harmonic distortion produced by tube amps is far less audible than the higher order, odd harmonics generated by solid state amps. Tube amps distort right in the audible blind spot so to speak. Another problem with the metrics is that they are measured with steady state signals, not dynamic musical content.

Tube amps as well as SS amps produce both even and odd order distortion, anybody who interested in verifying this should look at the measurements published at Soundstage.com or Stereophile.com. Certain circuit topologies produce relatively high amounts of 2nd order Harmonic distortion but that more of function of the circuit design rather than amplifying device. A measurement taken with dynamic content will not produce less distortion, steady state signals are used for simplicity.

[Feanor]

... There is still, however, a magic with tubes that most solid state amps are unable to duplicate. You can do that to a great extent by using a tube preamp or by using front end components with tube line stages. With my vintage system, I use a tube output Manley DAC with the Pioneer PD-54 CD transport driving the Stasis directly (no preamp) into double New Advent speakers. While the Advents clearly benefit from the control of the SS amp, the tube line stage provides much of the tube magic.

rw

How is it that putting a tube component in the circuit, say a preamp, can yield a tube sound even when that sound has been or will be filtered through a solid state component??

I just don't get that. On the face of it, the tubes have got to be adding something. Maybe 2nd order harmonic distortion that masks the even and/or higher order harmonics added by the s/s components???

[Geoffcin]

How is it that putting a tube component in the circuit, say a preamp, can yield a tube sound even when that sound has been or will be filtered through a solid state component??

I just don't get that. On the face of it, the tubes have got to be adding something. Maybe 2nd order harmonic distortion that masks the even and/or higher order harmonics added by the s/s components???

A lot of people like it on their ice cream, tastes better they say. Or salt, a lot of people like to salt their food no matter what it is. Think of those second order harmonics as syrup, or salt.

[JoeE SP9]

How is it that putting a tube component in the circuit, say a preamp, can yield a tube sound even when that sound has been or will be filtered through a solid state component??

I just don't get that. On the face of it, the tubes have got to be adding something. Maybe 2nd order harmonic distortion that masks the even and/or higher order harmonics added by the s/s components???

The one thing I'm certain tubes add is a smile to my face.

[Florian]

There is good SS, good Tubes, good Hybrids etc.... Single Ended, Direct Drive, OTL, Triode mode and Pentode mode....blah blah blah....there is not general advice.

:-) I would go for six 100wpc tube monoblocks with custom made 2ohm transformers.

[E-Stat]

Tube amps as well as SS amps produce both even and odd order distortion, anybody who interested in verifying this should look at the measurements published at Soundstage.com or Stereophile.com.

The relative amounts, however, are for the most part different. Again, the nature and spectra a tube amp's distortion falls within the the human auditory system's blind spot. Even small amounts of high order distortion is audible. It is only after forty years of solid state development that the best ones are beginning to fully challenge the best tube designs.

A measurement taken with dynamic content will not produce less distortion, steady state signals are used for simplicity.

THD measurements are averaged over time which does not show instantaneous peaks. The positively dreadful sounding Crown IC-150 measures only 0.001% THD under those conditions. The metric really doesn't relate to real world performance.

rw

[E-Stat]

How is it that putting a tube component in the circuit, say a preamp, can yield a tube sound even when that sound has been or will be filtered through a solid state component??

First of all, I did not say that adding an otherwise superfluous tube based gain stage would "improve" the sound. I have enjoyed improvements only when I replaced a solid state gain stage such a preamp with a tube design. All sins are cumulative. The more dirty panes of glass you look through will further obscure the view.

It for that reason that I don't use a preamp at all in either of my music systems. So long as you match gain and impedance, I've found that eliminating a gain stage altogether, whether tube or solid state, will improve resolution. I've yet to meet a perfect preamp at any price. That, by the way, is part of the magic of the ASR Emitter amps. While they are considered "integrated amps", in fact there is no separate line stage as commonly found. The input stage of the amp is of high enough gain and is battery powered to further drop the noise floor.

rw

[E-Stat]

Think of those second order harmonics as syrup, or salt.

And the odd order harmonics as vinegar.

rw

[Geoffcin]

And the odd order harmonics as vinegar.

rw

More like sand in your food. It doesn't take much to make you want to spit it out.

[Mwalsdor_cscc_edu]

Whenever you listen to a tube amp... that not all tube amps sound alike. Now you may be blown away when you hear your 1st tube amp. I was when I hooked up a Dynaco st70 to my Infinite Slopes and Rickie Lee Jones was suddenly in the room. That was enough for me but 15 years later I'm on tube amp number four. It kills the others [well, the VAC was special too] and I've heard numerous other tube designs in friends systems, show rooms or Audio get togethers. And like the others have mentioned, It important to find the right speaker for the amp your using. My combo is hardly ideal and it still makes magic to my ears. People tend to side with higher efficiency speakers with tubes because mega-watt tube amps can be expensive. Tubes are more like analog, whereas SS is more like digital. You should consider that tube amps require some fiddling with. Biasing and tube rolling. Trying different tubes is half the fun of tweaking the sound to your liking. SS is plug-n-play. Kinda boring. People will generalize that tubes are great in the middle registers but weak that the edges. My system has a nice top end extention and while my dual 6" drivers won't do deep bass the bass from the 45-based amp is some of the most musical I''ve heard. It really comes down to where your replay priorities are. No one component type can do all things well. So choose wisely.

[theaudiohobby]

The relative amounts, however, are for the most part different. Again, the nature and spectra a tube amp's distortion falls within the the human auditory system's blind spot. Even small amounts of high order distortion is audible. It is only after forty years of solid state development that the best ones are beginning to fully challenge the best tube designs.

The two diagrams below show the distortion spectrum @1KHz/10W of a typical SET and that of unbalanced SS, The main difference between these two graphs is that magnitude of distortion in one is considerably higher than the other. The SET amplifier has considerably higher distortion across the whole spectrum.

THD measurements are averaged over time which does not show instantaneous peaks. The positively dreadful sounding Crown IC-150 measures only 0.001% THD under those conditions. The metric really doesn't relate to real world performance.

rw

THD is irrelevant in the context of this discussion, as the distortion spectrum of any audio signal can be captured, And it is the distortion spectrum of the signal that is relevant here.

[E-Stat]

The two diagrams below show the distortion spectrum @1KHz/10W of a typical SET and that of unbalanced SS

Who said anything about single ended triodes? I use 450 watt tetrode amps.

THD is irrelevant in the context of this discussion, as the distortion spectrum of any audio signal can be captured, And it is the distortion spectrum of the signal that is relevant here.

I'll take the upper trace with the more linear spectra and far lower in relation high order harmonics.

rw