For tube sound, which is more important: preamp or power amp?
Preamp for tubes, solid state for the power. It isn’t purest way to use tubes, but the cost of a high powered tube amp (100% amp) or a power amp is prohibitive for most buyers. I’ve always had solid state amps, but on a hunch I bought the Monoprice 50 watt hybrid and have been surprised just how much the tubes make in defining the instruments, voices, and widening the sound stage. It doesn’t hurt the output amp is clean. I do believe my next new amp will be the Rogue. It won’t break the bank, and it gets high raves for a hybrid amplifier. |
BTW I like all tube for classical and jazz, but for rock you gotta have that SS pre-amp in there to drive that bass.That's pretty subjective- I find that my tube amps can play bass better than any solid state amp on my system. I play a lot of rock too. My speakers go to 20Hz and are 16 ohms so tubes play them easily. On top of that, my amps are full power to 2Hz, so no hint of a rolloff at any frequency the speakers can play. |
I utilize my massively powerful 12 watts per side Firebottle amp into 99db Klipsch Heresy III speakers (which, I might add, is plenty of power for these speakers), helped along with 2 REL subs adding 250 watts to the party. I like tubes for jazz and classical, and I also like tubes for rock, mumblecore, EDM, reggae, test tones, screechy animal sounds, and Harry Shearer's podcasts. The Freya's ability to go passive or FET provides an instant "what if I bag the tubes" reference, and I have a second SS Mosfet amp hooked up to the Freya outputs for extension speakers (Concentric tweeter KEFs, and I stick those in the windows to play to my deck...works great) that I can use as a SS reference if I wish as they're in the room also (sort of hidden generally but can be pointed into the room). |
Avanti1960 mirrors my own findings. Tube power amp definitely makes a bigger imprint on the overall magic than a tube pre-amp. Not only that, it is much easier and less fussy for a solid state pre-amp to drive a tube power amp. Not so the other way around. Tube pre-amps, even good one with strong output, will choke if asked to drive SS amps with input impedances much lower than, say 50 kohm or so. That basically rules out half of the SS power amps out there. BTW I like all tube for classical and jazz, but for rock you gotta have that SS pre-amp in there to drive that bass. |
I have not auditioned any tube preamps, but purchased a pair of ARC Classic 120s from here last year. Prior to that I had a single Parasound HCA 2200ii and then a 2nd running them in mono. This took me to 750wpc SS with a very well respected pair of amps with all the specs for great bass and dynamics. I have 86db floor standers. The ARCs at 110 wpc outshined them in every aspect....including bass! The output level was higher, more dynamic and more detailed. The smoothness of the sound is where I think the lack of ear fatigue comes in. I'm only listening to vinyl. Fast-forward 9 months and I'm wondering about SS again so I just picked up a B&K 200.2 and it sounds fantastic. It reminds me a lot of the Parasound. I listened for a day and then reconnected the CL120s and it was the same transition as before. I think I got very lucky in my choice of tube amp for my first experience since they each have 8 6550s as output tubes. Newer amps have fewer with a higher output/tube and maybe thats why they are so strong....not real sure. I would love to compare my ARCs to another tube amp, but that's not in the plan for now. I encourage anyone who hasn't had a tube amp in their system to figure out a way to make it happen. |
My understanding is that one of the reasons that low feedback may be beneficial, is that the feedback is very slightly out of time with and that the human ear is extremely sensitive to this.Its not a timing issue so much as a matter of distortion generation (while suppressing feedback, it adds some of its own). But the ear is indeed quite sensitive to this, because the distortion generated are higher ordered harmonics and the ear uses those to sense sound pressure. Combine that with how music energy is distributed over frequencies and that's about as sensitive as it gets due to the Fletcher-Munson curve! I prefer zero feedback, but 20 db of feedback is easier to listen to than 10 db or so. There's a sort of 'in-between' hump where a moderate amount of feedback results in audible problems that lower or larger amounts don't have. You are correct that there is a bit of compromise with the use of feedback, and frankly most designers fail to get it right as there are more variables than the old school formulas suggest! |
atmasphere I am curious that you suggest that over 15db of feedback need not be detrimental. Perhaps I miss-understood. My understanding is that one of the reasons that low feedback may be beneficial, is that the feedback is very slightly out of time with and that the human ear is extremely sensitive to this. Like all things, I am sure that the selection of feedback is a compromise, as is everything concerning the design of an amplifier right down to the quality of components and build quality. Some things, I am sure, are just down to plain old fashion. |
Is it possible that one of the reasons that Valve amps sound so good is that they tend to use much lower amounts of feedback that most transistor amps?You can either run high amounts of feedback or very low amounts; in between (about 6db up to about 15db) its application can be really detrimental. Feedback, while suppressing distortion, also adds some of its own, and the type it adds (harmonics 5th and up) is pretty audible. Even though its a very small amount, its audible because the ear uses those harmonics to sense sound pressure, so it has to have a 130db range! Tubes (triodes in particular) are very linear so it is possible to build zero feedback tube amps much easier than it is to do so with solid state. So, quite often, yes, this is one reason tubes can sound better than transistors. |
charles1dad, I now find that even though I have Triode and feedback switching on my power amp, I nearly always keep the amp in triode mode with minimal feedback. The maker of the amplifier said that these days most of his amps are fixed in triode mode with low feedback. He suggested that if I ever wanted to upgrade that I should try one of his single ended pure triode models. He thought that triode amps can often drive speakers better than ultra linear anyway if they have well designed output transformers. For now, even thought I rarely use it, I still like the option the switch modes and change feedback. |
Regarding tube maintainance, one can select a power amp that is not so high powered and uses output tubes such as EL34 or el86. These sound good and do not break the bank when they need replacing. Of course the amp still needs to be well designed and have good output transformers. I am amazed just how powerful some low output valve amps can sound. If I could only chose to have a valve pre or power I would still chose a good valve pre first with the intention to change the power to tube later. |
I went all tube- pre, amp, phono - more than 30 years ago, when SS amps were harsh and consequently, I had lost interest in recorded music. Solved that problem! Amps and preamps are equally important. As many above have noted, there are many ways to skin a cat. I think tube maintenance issues are exagerated. Yes you have to change them every few years, and they cost a bit. It’s trivial compared to what most here have spent on gear. We all have had to nurture some trouble shooting skills, and occasionally, soldering. No big deal. You can make an argument for ss amps based on less heat and power useage, and sometimes these can be controlling factors; I live in Houston, there are times I am not inclined to run all those tubes - but I’m not convinced that class D amps will compare. the electric bill (power and a/c costs) is a relatively minor consideration when you’ve spent tens of thousands on gear and content. Tubes are more musical. I really see no reason to use a SS pre. |
Iscm, As the level of negative feedback (NFB) is increased the output impedance decreases and damping factor (DF) is increased. Depending on the speakers involved the additional NFB can be beneficial up to a certain point. Generally speaking I believe that the less NFB utilized he more natural and open the sound quality becomes so I understand your listening observations. Some speakers are intentionally designed to work very well with low and even zero NFB amplifiers. I use a DAC, line stage and power amplifier and all 3 of them are zero NFB designs. The result is a very organic, lively and emotionally engaging sonic character. Charles |
I have been using a Conrad Johnson PV9a pre into a Quad 306 Solid State to drive my B&W DM70’s. The speakers are a Hybrid Electrostatic that are not the easiest to drive, so I thought that this would be the best combination. In fact it sounded great and gave great pleasure. However just recently I got hold of an Art Audio Quintet power amp. This has taken the system up to a whole new level. The soundstage has opened up and the sound is much more dynamic. These particular power amps allow switching from Triode mode to Ultralinear plus feedback switching (.5 to 6 db I think). I now find that I prefer Triode mode and minimal feedback whatever music is being played. Is it possible that one of the reasons that Valve amps sound so good is that they tend to use much lower amounts of feedback that most transistor amps? I have noticed that the sound seems to open out as I select lower amounts of feedback. Anyhow, I am shocked as to how well these amps drive my B&W’s even in triode mode with just 15 watts. I would not want to go back to using a transistor power amp on my main system. If I did upgrade in the future, it may be to a single ended triode, but for now I am more than happy. |
I agree with mofimadness. The preamp will give u the tone u want; the power amp will amplify that sound. IMO, u can't have a power amp that's too powerful. Class A bias is the way to go, if u can swing it. 600-1200 watts is good, depending on your speaker efficiency. U want something u can weld with. No clipping; good tight bass. Tube preamps👍 Some tube preamps have a bit of tube rush. They require low noise matched tubes. If you're in to quiet classical music, they may not be for u. |
Very late to this party but an interesting read. Which is more important? I could not figure that out so I bought a Raven Integrated Reflection MK2 tube amp that right now generates around 65wpc. Having an integrated tube amp provides me everything that I want and I could not be happier with the power, performance and the sound. I also like that I am able to play with tubes. I have 4 power tubes. I have tried 6500's, Vintage GE, KT 88 and now KT 150's. You do get slightly different sound with each one. I also have 12aT7's, 12AU7's, and 6922's. I like the convenience of one component as opposed to two. It is a showcase piece and everyone who comes into my house wants to know what it is. |
| Post removed |
Since getting new speakers, I am going to retract what I said earlier. I said preamp , but mainly because I have always held the preamp as the most important electronic component. I have been experimenting with tube compliment in my amps and am struck by how revealing my speakers are of any changes made at the input and also how different output tubes sound. They both contribute to the flavor, so careful matching is the key.....sometimes it's just trial and error and has more to do with luck than care. So YMMV |
Getting the two amps to work together properly will be a bit of a challenge. Unless you use an active crossover, I think you will find that to a very difficult task. The problem with using an active crossover of course it that its not actually tailored to the speaker, and every one that I've heard has imposed its own signature, which is why I try to avoid them unless they are used in a subwoofer. |
Interesting that this topic should come up again just now...Here's a copy of a question I logged on to ask... "I'm using a Rogue Audio Cronus Magnum 2 biwired to Vandersteen model 2cs...I have a chance to pick up a Hafler DH200 cheap. Seeking opinions as to whether biamping with a solid state amp to the low end will be a net loss or gain...I'm guessing that it will tighten up the bass, but I'm worried that it will detract from the signature tube sound of the Cronus. Opinions?" My best (remembered) sound was a couple of decades ago with an earlier iteration of the Vandersteens, a CJ tube preamp and the DH200 with Musical Concepts mods. (Mid fi...I know) Anyway, I'm going to pick up the Hafler and try it again...I'm not expecting an improvement, but we'll see...I'll post the perceived results on this thread if that's OK... |
Also, looking the specs of most tube power amps it seems the S/N ratio isn't nearly as good as SS amps. The THD numbers aren't as good either with 1% at full power not uncommon. SS amps' specs look considerably better. Is this typical?The problem here is that the ear puts a different weighting on what harmonic distortion is present. IOW, it almost does not care about the 2nd harmonic, but cares quite a lot about the 7th and other higher ordered harmonics. So a tube amp tends to have lower orders to which the ear is less sensitive; solid state amps have more of the higher ordered harmonics than tube amps. The ear translates all distortions into tonality. So the 2nd contributes to 'warmth'; the higher orders contribute to brightness and hardness. Both are colorations! The bottom line here is that although solid state amps appear to have less distortion, the distortion that they do have is far more audible and objectionable to the human ear. This is why tubes are still around decades on after they were supposedly 'obsolete'. |
My solution is to bi-amp, using a SET for the tweeter/mids, and a Push Pull for the woofers. And I use a PS Audio SS pre-amp, but in passive mode most of the time, which keeps me all tube. Only when I really want to blast the Stravinsky, do I add some preamp transistor. This set up pleases me a great deal. |
Danoroo, Those specification numbers will reveal very little in regard to component sound quality. You must listen and judge by what you hear. Again I find myself agreeing with the wisdom of Jond. I once owned a Symphonic Line which is a highly regarded German SS amplifier. It had excellent specifications and very good sound. Well my 8 watt SET amplifier took my sound quality and listening enjoyment to a higher tier. The SET's measurements/specifications on paper would be reconsidered clearly inferior to the Symphonic Line. Numbers said one thing and the ears said another, the ears won decisively. Now its definitely possible you could prefer the SS amp over the SET . My point is that listening is required to make that judgement not test bench results. Charles |
@david-ten I run Dirac Live to clean up the anomalies you mentioned. Also, looking the specs of most tube power amps it seems the S/N ratio isn't nearly as good as SS amps. The THD numbers aren't as good either with 1% at full power not uncommon. SS amps' specs look considerably better. Is this typical? |
@danoroo A word of caution. You are trying to do two things at the same time. If this was just about your optimizing the performance of the Enzos, via a tubed amp, it would be one thing. Adding sub control via the preamp may lead to coherence and timing issues and perhaps slight sound signature differences. I don't know the level of control you have via your preamp and your subs.....If you have a high level of software control, then perhaps the integration will be easier to achieve. |
@ charles1dad This 845 SET amp can be driven by my Emotiva XSP-1 SS preamp? The reason I want to use that preamp is because of it's bass management capabilities. I would like to drive the Tekton Enzo 2.7s with a capable tube power amp while connecting subwoofers to the preamp. Since I have never used tubes in my system and have no idea what sound characteristics they offer, I would like to keep my initial foray as economical as possible until I'm certain this the presentation I want. I appreciate you guys taking time to educate a noob. Thanks. |
Danoroo, As I am sure you realize amplifier selection ultimately comes down to what type of sound character you want. Different topologies and designs have their own sound and presentation. Generally 100 watt tube amplifiers are push pull and very often class AB. The 3 amplifier examples I mentioned above are 1Lower powered 2 Pure class A rather than class A/B 3 Single end rather than push pull Either of these broad categories are capable of providing excellent sound quality. It truly depends on what "you" are seeking. You are fortunate in the sense that your Tektons allow the use of either type of amplifier. In absolute terms there’s no universal "best" choice. Every listener has some degree of bias (I certainly do) as far as what sounds best, it’s all subjectivity pure and simple. Its a shame that we can’t hear everything we are interested in before buying but that’s the reality in many situations, so reviews and word of mouth opinions are utilized. As Jond said you have multiple options available due to your speakers. I’ll say this, the Sophia Electric mono block 845 SET at that price is honestly a fantastic option to consider. Given my past experience of hearing many speakers and amplifiers I believe that the Tektons/845 mono block pairing would be quite special. Usually a good quality 845 SET amplifier new is going to cost 5 or 6 thousand(minimally) and definitely go up from there. These are no nonsense high voltage designs that require very robust output transformers, parts and power supplies. This can’t be done cheaply. Sophia Electric makes very good quality amplifiers. Best of luck, Charles |
@danoroo As Charles has stated those Sophia amps will have no trouble at all driving your speakers at 98db sensitivity they were designed to be driven by tubes. And you will find 22 tube watts to sound much more powerful than you might expect. I am driving 93db speakers with 17 tube watts as loud as I could stand to listen no problem. And thanks Charles it was pretty easy actually. Tube Amp category and sort price low to high, under $2K they really jumped out at me! Good luck danaroo and you really do have tons of options with such easy to drive speakers! |
Danoroo, Given the Tektons you have, here are 2 other options to consider. Dennis Had 12 watt SEP (KT 88 tube). Wolf Garcia has praised this amplifier a "few" times 😊😊. Coincident Dynamo MK II version, 8 watt SEP (el 34 tube). Yes they’re both lower power amplifiers but would mate well with your Tektons (Lores?) . Overall sound quality would be very good. I must say however the 845 Sophia Electric mono blocks at that price is a genuine bargain if it’s in good condition. Charles |
Hello Danoroo, I’m with Jond 100 % with the Sophia Electric 845 SET(not push pull) amplifier and especially at that price! With your Tektons sensitivity and easy to drive characteristics, high volume shouldn’t be an issue. More importantly sound "quality " will be upper tier IMHO. This is a well regarded manufacturer who utilizes good quality transformers and parts. In terms of true high level sound quality it’s very difficult to better this particular amplifier at this price, very difficult. Many tube power amplifiers have an autobias feature but for those that do not biasing tubes is a pretty simple task to perform. Charles |
@danoroo Are you running Paradigm Persona B's? If so are you sure you really need 100 tube watts? They list at 92db sensitivity and 8 ohms. Looking at used moderately powered tube amps in your price range listed here this jumped out at me: https://www.audiogon.com/listings/tube-tube-monoblocks-lots-of-positive-reviews-4-000-msrp-2017-11-1... No affiliation with the seller just looks like a lot of amp for the money from a well regarded company. Good luck and happy listening! |
My now "resting" preamp is a Kavent S33, which is a rebadged (not sure why) Vincent SA-91…it even says SA-91 on the circuit board. These are fully balanced aluminum clad heavy monsters with a couple of serious transformers mounted in a separate shielded side of the preamp…it’s a large seemingly overbuilt thing, and has a 10 db adjustment to get higher output if necessary, and that’s the setting I used. I note that fact because the Freya has a more normal output level and the passive and FET modes are a more typical line level that I can actually run to max with my SEP amp (clearly my speakers aren’t THAT efficient), but the Freya tube setting is much higher gain to provide lots of headroom into my rig. |
I now have my Freya, and at this early point I can say it’s pretty damn good. The passive and FET modes are very similar sounding in my early assessment, and the tube stage is nice and hot with more than enough gain to send my Fire Bottle amp into the red zone …I replaced the "input" tubes with new Tung Sols although the original "mystery" tubes (no writing on mine at all, but they do seem to be tubes) work OK…the Tung Sols are simply dead quiet little things and sound great. No noticeable hiss or hum in Tube mode unless you stick your ear right on the tweeter in which case you can tell the tubes are there…and all in all a great sounding preamp. My previous preamp was so good it's hard to tell if the Freya is really better, but I have 15 days to figure it out. |
Granted, YouTube isn't a reliable tool for judging sound but Tyco Dogg has some interesting tests with the Schiit Freya preamp switching between tubes and Jfets, and between different tube sets. Here's one of the series: https://youtu.be/1Slu3u0o4Aw I seemed to hear a difference in tube sets, but not so much between Tung-Sols and Jfet, which seems odd |
Danoroo, The pertinent question has been poised, what’s your budget range for the tube power amplifier you seek? A good quality 100 watt tube amplifier doesn’t have to be necessarily expensive but they won’t be "dirt cheap" either. Good quality engineering, implementation and parts/transformers/power supply do have a cost that’s worth it in the long-term perspective. Charles |
