Solid state; when would you use tubes?

The Music Direct catalogue company say's best selling product they have ever sold has been $399 tube buffer which basically introduces a smal driver 12AX7 whereever you wan to "tube things up".I think this is kind of stupid because essentially when you hear the "warmth" (or "bloom" or "euphonics") of tubes you are esentially hearing a pleasant form of upper order distortion (as opposed to lower order distortion which is what we call "distortion").Some CD modifiers add tubes to the output stages of their work which I don't like idea of again because I want source to be as clean as possible.Maybe it is I am who am being stupid because I have this bias but I think tubes should have thier effect as part of an essential component either the pre-amp or or power amp.The advantage of tubes is they are warm and have timbre which ads to primarrily the midrange.Folks who want to emphasize this will normally pick a good two way monitor and use an EL34 tube in a power amp or integrated or power amp to get it's gretates effect.What tubes do badly is is conmtrol the frequency extremes of bass and trbile where GENERALLY solid state does a bter job.But you will read in reviews of some pre-amps and power amps them say it is a good piece because it in fact handles the bass tightly with conytroll and there is no frequency roll off at the extremes and treble is clear etc.One thing is that is nice about tube amplifiers is that when you overdrive them the distotion comes on more gradually than it does than with solid state designs (part of reason that tube power watts are percioved as being louder and as a rule of thumb making a tube amp eqaul in power to a solid state design that is rated as being twice as powefull).Didn't fully undertand it all myself but the designer of Pathos a beautifull looking and great sounding (with right speakers) hybrid amp combines a tubeline stage with a solid state output(power)stage to take advantage of both of what tubes and solid state do best.He said that tonally a tube pre(line) stage converts voltage beter than solid state but for the reason mentioned before bass control and and frequency roll off at extremes the solid state mosfet of today do beter job at output stage.Other than Pathos a really well regarded and highly reviewed hybrid is the Unison Company (another Italian Job).High percieved value for the dollar.

Now question is should you get a hybrid or a tube pre?But wait.of course thier are companies that make only tube gear so obviously not everyone assumes that the strategy above is best.Their are also all tube integrateds as well.Deopending on your tastes nd the quality of equipment you may want all tubes.Or as one time when first understanding this and talking to an audio dealer I told him that I thought I would do what "most" peopl do and get the sweetness from a tube pre and the control from a solid state design.But he was being provacative with me and said "why not get a solid state pre and a tube power amp?"In fact all things being equal you will get more of a tube signature on the sound by going with a tube amp (and SS pre) than you will the other way around.The reason that many folks get the tube pre and solid state power amp is that the tubes in pre's (driver tubes in all tube amp are same)are much longer lasting and cheaper than the output tubes cheaper than the power tubes are.The tubes in a pre are like part of the set up in an all tube power amp.A tube power amp will have a set of input (driver) tubes and another set of tubes which are the output tubes bigger,hoter,and neeeidn replacement about every 3,000 hours of play.Pre amp or driver tubes can last up to say 10K hours (bu I may be off with those numbers).Here's another neat thing about these pre- amp and driver tubes.You can find NOS (New Old Stock)tubes of U.S.,England,Germany,France etc from the 50's60's which have ,as a rule, much beter sound than the tubes made now in China ,Yougoslovia, or Russia (why the eastern block?because the west was farther ahead in miltary technology with IC's whereas the Eastern Block countries for a much loner times and still today rely on them for Military and industrial applications).Changing tubes or "tube rolling" with a pre or input set on a tube amp can be a lot of fun anm really improve the sound of tube gear.probvaly the best the country that made the best tubes was (of course)the Germans and thusly Siemans or Telefunkens can be much more expensive than US GE's and RCA's,or French Mazda's etc.One exception maybe the Brits with Mullards.The cost of output tubes is for most folks price prohibitive and they are very hard to find.One last thing about tube amps and tube integrateds is tube biasing.The output tubes of an amp will after a while go out of bias and require with many amps and one needs to either use a meter bought from Radio Shack and apply the meters point whjile adjusting a screw to add bias currecnt to get them to last longest (some say to sound better but I don't notice difference).Now many folks like me since one at maximum has to this each moth (and depending on how much you use amp much longer if listened to less).Some folks like me find this easy (one amp I had a Conrad Johnson did not require a meter it had little lights that would indicate proper bias when they went from on just at the point they went off).With a integrated amp I would want (and in fact have) an amp that is self biasing so I don't have to bother with it at all (pop the top would be a hassle) that's why most tube power amps have cages easy to rmove to protect kids and pets and many folks levae them of or they have no cage and assume you'll put the amp in safe shelf where Rugrats and Fido won't get hurt.I kind of miss biasing the amp but the EAR I have is easy I just have to think aboiut tube life and replacfe when necessarry and that can be donme at shop or some comsumers invest in a tube tester and do it themselves.So I guess self biasing power and integrated amps are easiset but there are those who say improperly designed autobiasing circuts rob power.So geting one of these or just a ube pre-amp (again prbaly the most popular use of tubes) is easiest.But don't decide until you've gone into a shop and listened to the equipment and have the biasing if needed expained and demonstrated.

Next as far as "what should I get" depends on your speakers.It's a different world now since many solid state designs that used to be harsh or cold are now made to sound more like tube gear.And tubes which used to have mushy bass and weak rolled off highs can now sound like they have iron fisted control with tight bass and alpine highs yet still deliver that m,idrange magic.But it is the interface with your speakers that will lae the difference.Solid ste is easier to choose because most brands that aren't bottom of the line garbage will be able to handle down to a 2 ohm load and remain stable (not distort,overheat,shutdown).Soem tube amps can with their ammount of power and design also handle a "difficult" load.Most speaker will have a nominal load between 8 ohms and 4 ohms.Speakers with an "easy load" will be 8 ohm nominal with a high senmsitivity.But as with almopst all Hifi statistics one alone can be misleading.I sold hifi for a number of years and had the best selkling import englands B&W.My favorite speaker in thier $300 to $12K line we had was the B&W 803 nautilus.I thought it delivered the best bang for the buck followed by the entry level of the best 800 series the 805 which were two way monitors.Now if you looked at the 803 with a 8 ohm load with a 90 db sensitivity.The higher the sensitivity the easier the speaker is to drive.In terms of loudness you needed to go from say 87db to 90 db to hear a speaker as louder.When you increase a speakers sensitivity by 3db it is like oublking the power of the amp going froma 50 watt to a 100 watt amp.Most speakers are either a 4ohm or 8ohm load with a senditvity of 84 to 89 db sensitive.Take a poluar sized tube power amp of 45 watts.I say popular because price.Generally speaking people say "You can't have to much power" which is kind of true but if a speaker if a small monitor which has a power rating of 100 watts RMS (continuous power) to put a 150 or 200 watt amp could be wastefull or even damage the speaker.But contrary to what most folks intuit having to LITLE power where with a low sensitivity speaker you take a small amp and bury the volume what happens is the distortion lights go on.And if the amp has them and they go from blinking to solid.You could see the swooping wave from on and ossciliscope go from "swops to being squred off.Tha's distorion heat and eventuallya loud "POP" and you get no more sound and a burnt smell in the room.But with too much power you have the speaker staring top sound bad earlier and you are less likely to blow them because you back off the volume.Now back to those B&W's.

Beacause of their size and drivers etc and it's load (closer to eight than 4 if not an easy 8 ohm load)they may be rated to say 89 db of sensitvity but I the audio saleman say it's a good match and you pout them on and fall in love wioth the sound of the tubes and this nice $2K monitor.Then you ask me what I think is the best speaker in the room.Well of course it's the $12k 801 which the biggest speaker in the place.But then you say which is the best BANG FOR THE BUCK??? and I say the little 805 is second but the best value is not the next speaker up the $4K 804 or the $8K 802 nor the biggest most expensive 801.I tell you it's the middle child the $5K 803 which delivers the midrange they all share but it has the deepest bass and biggest soundstage PER DOLLAR of all of them.Know you know the 45 watt $2K integrated amp I have showed you powereed up th small 805 monitors with 8ohm load and 89db sensitvity.Then you look at the specs of the 803N I say I am saving up for and see that the specs say "8 ohm load 90db sensitivity".So you assume it's so close to the monitor you could get the 45 watt amp and the $5K speaker.But you can't.Because the 803 states it is 90 db senstvity because iof it's size and design it has a nasty impedance dip that can go down to 1,5 ohms and would either damage the speaker (more likely) or the amp or both.I tell you that you need to spend $5K on a tube amp with 100 or 140 watts from same manufacturer toi be able to run the speaker safely.But as you have heard 100 to 200 TUBE watts is expensive (a solid state design could achieve this jump in power for much less money).And I would say that you can drive 80% or the speakers out there with 100 tube watts.200 tubes watts and you can drive just about anything.but some companies make 400,600 and up hugely expensive tube amps that will give the most demanding design or size speaker power with room to spare which is a good thing if it's a demanding speaker ina big room and you want "headroom" for sound quality and safety's sake.Maybe this last paragrapgh is too involved and makes it all sound more complex than it is guess I am just being thurough.An audiosaleman at a place that has tubes should be able to guide you and your freinds here on Audiogon with be as thurough as I am only they will probably understand the brevity of wit better than I do.Second to very last thing is tube types.Differeet driver and power tubes are out there.You might see and amp with the right price point with KT90's or 6L6's.But three popular power tubes are EL34's which are the midrange champs.6550's are a good all around tube and good in an amp where you have to replace because they are cheaper than others.I read somewhere that they have the most bass but I have always read that this is the domain of the third most popular tube the KT88 which have slightly better bass than others and the most dynam,ic "slam" or "speed".Some of the differences are subtle to some ears they are not.
In sum I think you need to take into account your spoeakers.The ones you have are they long term keepers?If your dedicated to them you'll have to make all of the decisions based on them their characteristics and your budget.If they are small to midsize speakers that are easy to drive you might want to get an tube integrated amp or tube pre and power amp (and like i said the tube police will not haul you off if hear tubes and want what they give but don't want to give up your nice McIntosh solid state pre with a tube amp to follow).You may find that because of the demands of the speaker or because of budget you neeed 200 or more of solid state power and just can't lay out $5K for a tube amp big enough to run them.So then you get a tube pre-amp have the lest problems (or if you like it "involvement" ) with your new foray in tubedom.Let a salesman you trust or the denizens of Audiogon or Audioasylum help you with reccomndations.I guess coming here you risk geting involved with manic,insomniac nutbags like me (I haven't even told you about the "flea powered" amp guys who restrict themselves to 20 speakers in marketplace of thousands because they need such high efficiency speakers because they like thre or 4 esorteric expensive SET ( single ended triode) amps that oput out 6 watts per channell.They are the lunatic fringe and proud of it since of course to them it's the best).But if you let a salesman in shop guide you you will be guided by his or her biases and here you have lot's of loonies to guide you have have had every combination and type of equipment before and you also can consider buying used versus new and of course in a shop you will be guided to the product on hand at retail prices.I shouldn't knock them because I have been one of them on and off since college in the erly 80's.So if it's tube sperates or just a tube pre it's really fun and they do sound great .So let us know your curent gear,budget and tastes and you'll be in goood hands from their.Hope you didn't want a quick and dirty answer and didn't mind Tube Audio 101.
G'luck
Chazzbo

I am looking for a more holistic answer, and less a solid state manifesto.

Chazzbo: I thought I was the only insomniac who wrote rambling minifestos. However even with your mind going at the speed of light which it doesn't by rules of nuerotransmision it can work at more than one thing at once and become a tad congested as if you apply too much power to a high efficiency speaker. All that being said you have outlined much of the conventional thinking about how to incorporate tubes into your system. Many of my audiogon buddies have been proponents of the sure footed, albeit no fun in finding small NOS signal tubes, SS preamp with a tube power amp. This yields the beauty of tubes without the combined distortion of using both Tube pres and Tube power. I personal use the more common complicated tube pre with 6 nine pin miniatures rolled to my heart's delight, with SS amps. You didn't mention that tube rolling can become an insane and expensive addiction by itself, I have more tubes than I will use in several lifetimes, sometimes called hoarding but really a sign of mania or obsession. That is what you call a tangent not manifesto BTW. The point I was attempting to make although I read your stream of thought rather quickly, is that the latest development is to go from a tube or non tubed source directly into a tube power amp. Only if you one source as do many I use a few. This avoids the problems of a pre altogether. The other option for those considering tubes is a moderately powered tube integrated which I own which is generally quite affordable and uses a classic topography of small input tubes, to drivers ,to power output tubes with the correct transformers along the way. I believe this has been around for decades and is called the Mullard Longtail configuration.
That last option can be very satisfying and does not limit your speakere choice to the exent SETs do. Mine drives VSA VR2s to listenable levels without excessive or audible distortion and they are 89db but hold their impedance with only a 6 inch midrange and a 6 inch woofer per, 2 tweeters but they draw almost nothing.
To answer your thread question the cliche is you use solid state-
A. If you prefer it's sound because tubes, which do not I repeat to not roll of highs tubes generally birighter sound desirable "sparkle." Your SS amp may in fact have greater roll off in the teble than tubes. OR
B.) When you cannot tolerate loose bass because most tube amps that are affordable anyway cannot deliver 100watts or more which is needed to control a bass heavy sound . So you do
C.) The classic biamp solution which has the benefits of both an amp or pair of monoblock tubes for the trble and misrange in a biwired speaker for the magical soundstage and beauty of tubes (depending on the one you choose EL34s as he said are great midrangey tubes even sweeter but less potent are EL84s ala Manley Stingrays et. al. and a potent SS amp to power the woofers/low end. There are tricks for doing this such that the volume output from both amps is equivalent. Do a search on forum topics and you'll find plenty of info, on how it can be done. If not here then search the AA site for FAQs and they have a detailed description for you.
To sum up You use tubes if you are manic and sleep poorly or when you really want musical involevement, deep and realistic sounding soundstage, and tonal timbrance that only tubes seem to deliver. But please make no mistake except with non refurbished or up non graded low power vintage- tube gear pre solid state era -i.e. pre early 60s -you will not get a"tubey" sound which people still think means dark, closed in, ill defined and rolled off sound. Use tubes when you hear them set up properly and like what you hear.
As a suggestion if you aren't using very demanding speakers try an inexpensive tube integrated just don't think it will play the crescendo of "Freebird" at 100db.

Chazzbo: I will forward what a tube buffer can really do which has more to do with its ability to act as a follower letting the impedance your source sees as virtually zero, thus giving the source all the power the source can providee and the power of the buffer, to manipulate the signal in an unencumbered state. The desesigner of REX speakers (see the latest 6 moons) is a friend and one one those Russian physics genius types who built one with a log or actually greater strength than the X-cans.He explained it to me. I too thought it meant using tubes to alter the sonics but it does so in a most indirect way they never serve as "active" tubes and don't supply any gain, they are passive, they are "buffers" only.

Biomimetic: If you are used to solid state and are curious you really do need to do yourself a gear favor and get up close and personal with an all tube based system for awhile. I was a complete solid state fanatic and for years vowed I would nenver go near that archaic technology, but now I am converted. Over the past two years I have assembled a second all tube based system around a CJ integreated, their CDP, a tube phono stage, and modest speakers and TT. I now listen to this system 90% of the time simply becuase I can listen to it at any level and I ALWAYS get pulled into the music without even trying. In fact I am listnieng to it as I write and am constantly distracted because this system, the total of which goes for about $5K, sounds so damn good. So mark me converted. Don't go partial on this, go whole hog and be happy.

FWIW, My first tube purchase was a tubed CDP (Cal Aria) in the mid 80's. BIG tonal improvement! My next tubes purchase was in a Pre-amp. Even bigger improvement. I upgraded to a Trans - DAC (Tubed combo). Similar tonal balance but with greater resolution. Several years later I purchased my first tube amp. Last year I purchased my first SS CDP since my original SONY 101 just to see what high quality CDP's can sound like w/tubes in the Pre & amp. Pretty good I'd say. Lacking a tad bit of air in the highs, but a very solid and musical sound (Wadia vs BAT).

In retrospect I think, at least for me, the pre-amp was the greatest single improvement and the amp was the second biggest improvement. I don't think one necessarily needs a tubed CDP or DAC any longer for high quality sound.

FWIW - YMMV.