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Post by AudioHTIT on Apr 30, 2015 17:11:21 GMT -5
Hope I am not going too off topic on this but regarding the tube sound - let's say you have an XMC-1 and make the switch from solid state to tubes. Would you have to run Dirac again? Since tubes do change the sound, would Dirac then compensate for that to make your system sound like it was before you changed to tubes? Interesting question. While I have seen some tube amps with slight variations in frequency response, I haven't seen seen a 'quality' amp that had enough variation in the audible spectrum that you'd want to compensate for it. Generally the sound of a tube amp is not attributed to variations in frequency response, therefor that function of Dirac shouldn't be affected enough to produce a different curve. I'd also doubt there would be any variations in the time domain, even though SS amps are typically much 'faster' (higher slew rate). I would speculate though for those who compensate their systems after running Dirac (more bass, etc), that the compensation might be different because the perception of what's 'missing' is different. As to the OPs question, most of my adult life I had a pair of Dyna 50W monoblocks. Though I bought them for my guitar (to use with JBL's), I tried them with most of the speakers I owned; various Magnepans, Beveridge Electrostats, and B&W's. They always worked well, but weren't satisfactory with the big Maggies or ESLs for more than casual listening, I used my Threshold 4000 (200W x 2 Class A) most of the time. About 10 years ago I got the VTL MB450's to drive the big Maggies, and essentially skipped over the mid-range power tube amps. These are either 450W a side in pentode, or 200W in triode, I prefer the extra umph of pentode mode, they have plenty of power using anyone's scale. Bottom line IMO, is that the match between speaker, amp, room and listening habits is so variable, that making generalizations about power and sound is almost impossible (but that doesn't mean we shouldn't try). I have also used one of the original Mac 275's and if your considering that, it would probably do a great job with many speakers in many rooms (though I'd probably pick something different with the B&W 802's you were previously considering). |
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Post by brubacca on Apr 30, 2015 17:26:24 GMT -5
I find it comical that we have gone from tube rolling to using tweaked microphone files for Dirac.
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Post by monkumonku on Apr 30, 2015 17:36:28 GMT -5
I find it comical that we have gone from tube rolling to using tweaked microphone files for Dirac. I think the first mic files were better than what are being produced now. Maybe someone can sell them for high prices by marking them as NOS. |
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Post by novisnick on Apr 30, 2015 17:41:22 GMT -5
What Distortion?  Sweet! |
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Post by novisnick on Apr 30, 2015 17:48:40 GMT -5
Rickie, I think any questions on the differences between tube and Solid state should be welcome here. I myself would like to learn from others as much as possible. The tube amps are beautiful and add a classy approach to a 2 channel listening environment. " tube amps are beautiful and add a classy approach to a 2 channel listening environment." And y'all call me the Monoblocks Snob!!!!! WELL!!!!!  |
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Post by snacker on Apr 30, 2015 17:55:41 GMT -5
I'm not sure exactly what it is with tube power amps that leads one to believe they are more powerful than their solid state counterparts, but I too think their is a difference. I was over my Emotiva buddy for life "snackers" place last night we finally got a chance to switch out his speakers from the 105db efficient Klipsch La Scala's to the 86db efficient Maggie MG12QR's. We were both interested in hearing how well the 50watt/channel Yaqin MC30-L tube amp would do with a planer speaker larger than my MMG's. We were not disappointed that little tube integrated amp seemed to take charge of the MG12QR's just as good as it does the MMG's. We also noticed that the sound of the two very different speakers were very close to each other in that space. With the La Scala's he couldn't use the amps remote control because just the slightest touch would increase the volume a lot. They were so efficient the volume rarely exceeded 2. With the Maggies the volume control is around 4, or 5. Not a thing was lacking and the tube amp didn't seem to be taxed at all. I agree with j 50 watts tube seemed to be more than enough to handle maggies. Had to put jmasterj to work yesterday, they got a little dusty.  |
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Post by audiobill on Apr 30, 2015 17:59:03 GMT -5
I find it comical that we have gone from tube rolling to using tweaked microphone files for Dirac. I sure wouldn't!!! |
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Post by ocezam on Jun 1, 2015 22:50:12 GMT -5
Watts are watts. There is no magical property with tubes that make them behave as if they were more powerful. Tube amps do clip softer than solid state. Significantly softer. If you don't have great ears, maybe you are clipping your tubes and therefore they seem more powerful.
Also, I am in my mid fifties and am enjoying my tubes, as I enjoyed the tubes I had before them. And the ones before that... Modern tube amps sound very good. It's not some kind of retro flashback.
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KeithL
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Post by KeithL on Jun 2, 2015 10:28:29 GMT -5
As someone already said, "power is power" - and the rated power is simply the rated power. Therefore, "75 clean watts" is going to be exactly the same whether it's coming out of a tube amp or a solid state amp. If we were to follow your "horsepower and torque" analogy, then the tube amp has neither more horsepower nor more torque. However, tube amps do have rather different distortion characteristics.... and this affects how they sound in several ways.... 1) Tube amps don't clip suddenly like virtually all solid state amps. If you overdrive a solid state amp, once you reach its limit, it will start sounding very bad very suddenly. In contrast, a tube amp will start sounding gradually worse and worse as you exceed its ratings. Since music is very dynamic, the average amount of power you use when playing music is typically 1/10 to 1/20 of the average power, with peaks only occurring a few percent of the time. This means that, with music, the peaks will start clipping long before you're anywhere near their actual maximum average output power. If you turn a solid state amp up too loud, it will start clipping the peaks very harshly, which will sound nasty. If you turn an equivalent tube amp up equally too loud, the occasional clipped peaks will be distorted, but the distortion will not be as obvious or as nasty. So, the tube amp and the solid state amp will start clipping at the same point but, if you keep turning them both up, the tube amp will let you go a lot further into clipping before it starts sounding really bad. 2) Solid state amps tend to have an overall distortion profile such that their distortion remains very low as you increase the power until you reach their limit, at which point the distortion rises very suddenly. In contrast, many tube amplifiers have what's called "a monotonic distortion curve". What that means is that the distortion rises gradually as they produce more power. (With some SET amps, the distortion actually rises linearly with power; with most pentode and ultralinear amps, while their distortion stays reasonably low at low power levels, it still rises more or less linearly at higher power levels until they reach clipping.) Now, interestingly, our human brains tend to interpret distortion as "loudness" (probably because it's annoying). Just think about how "loud" a cheap table radio seems to be able to play - because your brain interprets the annoying distortion it produces as "loudness". So, as you turn up that tube amp, not only does it really play louder, but the rise in distortion as it delivers that higher power makes it sound proportionally "even more louder". As you turn it up, the solid state amp delivers: 1 watt @ 0.01% THD, then 5 watts @ 0.02% THD, then 20 watts @ 0.05% THD In contrast, a typical SET 20 watt amp may deliver: 1 watt at 0.1% THD, then 5 watts @ 2% THD, then 20 watts at 10% THD You can think of the distortion almost like a "multiplier" on how loud it "sounds" - or like a "psychoacoustic dynamic range expander". A 75 watt solid state amp playing music at an average level of 20 watts will probably be clipping a few percent of the time - and will sound rather harsh. A 75 watts tube amp playing music at the same level will probably be clipping the same percentage of the time - but it will distort just enough to make it seem like it's playing louder, while still avoiding sounding harsh enough to be perceived as sounding really bad. 3) I should also mention that, fifty years ago, many companies under-rated their equipment more than is common today (so "a 50 watt amp" may really have been able to deliver 75 watts). This was true partly because some were simply rated very conservatively, but partly due to that gradual distortion characteristic I mentioned. (If a given amplifier could deliver 50 watts @ 1% THD, and 75 watts @ 10% THD, and you wanted to rate it at 1% THD, then your rating was "50 watts". However, it still had lots of headroom which it could use to deliver much louder peaks while only distorting them somewhat rather than clipping them outright.) Therefore, to be precise, with tube amps - as compared to solid state amps - there tends to be a "disconnect" between "how much clean power they can deliver" and "how loud they can play before they start outright clipping" - but that disconnect is really due to how they distort at various power levels and not to how much actual clean power they can deliver. I have been trying to expand my knowledge on Tube amps. Obviously a common question is "why is the rated power so low, and will they drive my speakers as good as X solid state." I am in the same boat, I'm a numbers guy. The other day I decided I was going to put it to the test and hooked the Olympicaiii up to our Mcintosh MC275 amp (2 channel 75 watt tube). My finding was that they sounded FANTASTIC and the lower end had a robust, full sound. The olympica prior were hooked up to a 5 channel 200 watt Mcintosh amp with only the two channel driven. The tubes didn't seem to get taxed at all. We also keep the ML Montis hooked up to our MC275 and they sound sublime without feeling taxed at all. So here is my question to someone who has previously jumped heavily into this question. Assuming the amps are in the same family. What is a general power rating from tube to solid state?. Ex: 75 watt tube = 200 watt solid state. Is this even an assumption that can be made? I'm looking for a general blanket statement. "Generally 75w tube amp will compare in power to a 200 watt solid state" Would you use 75Wx2 to power your high end, not very sensitive speakers? I have a general understanding on the distortion qualities of tubes being more gradual hence not sounding as harsh as solid state amps, and also the increase voltage making the tube seem more powerful. I interpret this as horsepower and torque working together. Let's discuss, and as always thanks for the insight! |
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Post by KeithL on Jun 2, 2015 11:09:26 GMT -5
Another thing worth mentioning is damping.
A typical dynamic woofer has a resonant frequency. The cone has mass, and the edge suspension, the spider, and the air in the cabinet (if it's a sealed model) all add up to act like a spring. If you take a speaker in its cabinet (don't connect the terminals to anything), and tap the woofer, it won't produce a nice sharp "thwup"; instead, it will produce the sharp thump you expect, but will continue to ring for a few tenths of a second, producing a tone that trails off over several seconds. (The mass and the spring act like what happens when you push a rocking chair - it moves when you push it, but it doesn't stop when you stop pushing, rather it keeps moving back and forth after you stop until it "uses up" the energy you imparted to it.) Bass reflex speakers are more complicated to explain because the air in the port is tuned to "counter resonate" to control this at specific frequencies.
In general, since this ringing is sound that is coming from the speaker when you aren't sending any signal to it, it's preferable to minimize or eliminate it. (The ringing is what makes a speaker sound "boomy" or "loose" - or to "boom at one frequency".) Now, there are two ways to reduce this ringing. The first way is simply to design a speaker that has less resonance. You can do this by putting a lot of stuffing in the cabinet (which adds mechanical drag to the motion of the cone), or by using materials in your suspension that use up energy as they move. You can also use special cabinet tunings to counteract it (which is what bass reflex cabinets do). The second way is electrical. A speaker is essentially an electric motor - when you put current through the voice coil, the resulting magnetic field pushes against the fixed field from the magnet, and "drives" the cone back and forth. However, every simple electric motor is also a generator. So, if you push on the cone, it moves the voice coil, and the voice coil moving in the magnetic field generates an electrical current - or at least tries to. Without going into the theory too deeply, if you short circuit a generator, it becomes very difficult to move.
Earlier I suggested that you tap on a woofer - while the speaker wasn't connected to anything. Now, short the terminals on the back of the speaker with a piece of wire and try it again. You'll find that it rings much less, and you get a much "sharper and cleaner" thump when you tap it. This is because, as the speaker moves, the voice coil is trying to generate current, and the wire you added is shorting out that current. Basically, you've just added "electrical dynamic braking" to your woofer.
This is precisely what damping factor does. When your amplifier sends a signal to the speaker, that signal produces current flow in the voice coil, which drives the cone. When the signal stops, the cone tries to keep moving, which causes it to try and send current back through the amplifier. The amplifier than shorts out this "back EMF", which applies a braking force to the speaker cone, and so keeps it from ringing (or makes it stop sooner). The higher the damping factor on your amplifier (and the more powerful the "motor assembly" on your speaker) the more effective this mechanism is.
Now - a bit of history.
Because of how they're designed, typical tube amplifiers have very LOW damping factors (between 5 and 10 is typical). This means that they DON'T do a very good job of applying electrical damping to a speaker. Therefore, speakers designed when tube amplifiers were the current technology (and modern speakers specifically designed to work well with tube amplifiers), are designed to not expect much electrical damping from the amplifier. They may include lots of mechanical damping, or they may compensate for the bass ringing by simply reducing their bass output a little bit so the total comes out right.
Now, modern solid state amplifiers tend to have very HIGH damping factors (between 100 and 1000 is typical) and, because of this, modern loudspeakers are optimized to work their best with lots of electrical damping. Modern woofers tend to be heavy, and have very powerful magnets, which means they have "very powerful motors". The high mass of the woofer means that it stores lots of energy, and "expects" the amplifier to control that energy by providing lots of electrical braking to control the motion of the cone.
The upshot of all this is that, if you connect a speaker designed for use with a tube amp to a modern solid state amplifier, it may end up being "overdamped". The amplifier is controlling the cone very tightly, while the speaker already has other measures in place to control it, with the result that it is "overcontrolled" - and you end up with thin sounding and anemic bass. And, if you connect a speaker designed for a modern amplifier to a tube amp, it tends to be "underdamped". The woofer basically has inadequate braking to control it (because the designers of the speaker assumed the amplifier would be providing that damping - but it isn't). The result is that the speaker sounds "thundery", with too much bass, but all at one frequency, and seems to flop around a lot.
Although I personally prefer to have the amplifier control the speaker with "an iron hand" rather than "trust" the speaker to control itself, it's not really so much a matter of "right and wrong" as of compatibility. However, it does mean that, if you plan to use a tube amp with a speaker not specifically designed to be used with one, you need to make sure you pick a combination that works well together, and you shouldn't expect that speaker to sound the same as it did when you heard it connected to a solid state amp. (Also, as a general statement, it means that, if you connect many modern speakers to a tube amp, you can expect "lots of not especially tight sounding bass that doesn't seem to go very low". )
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Post by 134lrs on Jun 4, 2015 7:42:40 GMT -5
I have VERY little experience with tubes but wanted see if you guys can confirm an opinion that a relative of mine has on the subject. I have heard that tubes perform on what I would describe as a bell curve. Basically he has said that Tube amps are a little rough at first but as the tubes age they seem to sound better and level out and finally, they start to drop off. He basically said they are like the brakes on a car. You may not notice that the performance of you brakes are fading until you replace the pads. This is why he has moved back to solid state. He said in his opinion, it is much more consistent.
I believe that sound is generally subjective. What sounds wonderful to me may not sound great at all to you. Would the above description be accurate?
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Post by pedrocols on Jun 4, 2015 8:26:54 GMT -5
I have VERY little experience with tubes but wanted see if you guys can confirm an opinion that a relative of mine has on the subject. I have heard that tubes perform on what I would describe as a bell curve. Basically he has said that Tube amps are a little rough at first but as the tubes age they seem to sound better and level out and finally, they start to drop off. He basically said they are like the brakes on a car. You may not notice that the performance of you brakes are fading until you replace the pads. This is why he has moved back to solid state. He said in his opinion, it is much more consistent. I believe that sound is generally subjective. What sounds wonderful to me may not sound great at all to you. Would the above description be accurate? Some people find LPs superior to CD or Flac files even with the pops and clicks. |
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Post by frisco on Jun 4, 2015 10:50:33 GMT -5
This is a very helpful discussion about amps. How about preamps--what is impact of a tube preamp when you are using a solid state amp, especially one with high damping.
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Post by 134lrs on Jun 4, 2015 10:53:44 GMT -5
I have VERY little experience with tubes but wanted see if you guys can confirm an opinion that a relative of mine has on the subject. I have heard that tubes perform on what I would describe as a bell curve. Basically he has said that Tube amps are a little rough at first but as the tubes age they seem to sound better and level out and finally, they start to drop off. He basically said they are like the brakes on a car. You may not notice that the performance of you brakes are fading until you replace the pads. This is why he has moved back to solid state. He said in his opinion, it is much more consistent. I believe that sound is generally subjective. What sounds wonderful to me may not sound great at all to you. Would the above description be accurate? Some people find LPs superior to CD or Flac files even with the pops and clicks. I understand this. I wasn't getting at what sounds better to who. I suppose rereading my post it may have sounded like an X vs. Y post. I was curious about if tubes perform in the described manner. Like I said, I have very little experience with tubes. I am however very interested in them and want to learn more from this thread. |
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Post by KeithL on Jun 4, 2015 13:51:06 GMT -5
I would say that's a fair statement. A brand new "fresh out of the box" tube will behave a certain way. Then, while running for the first few hours, some of the operating characteristics change a bit (for one thing, various gases "boil" off the surface of the cathode, which alters the surface characteristics of the cathode, and contaminates the vacuum a tiny bit). After a few hours this "levels off" and nothing changes significantly for most of the tube's "natural life". Then, as it nears the end of its life, changes again start to occur. How significant the changes are will depend on the particular tube and circuit that are involved (with certain circuits the electrical changes will cause the sound to change, while other circuits will prevent the electrical changes from being audible). Different designs also stress the tubes to very different degrees, and some tube types, and even some tube brands, "age" differently than others. Many modern tube power amps quote an "average tube life" of 5000 hours, while many owners of vintage tube preamps have literally never changed a tube in twenty years (and may never have to). I have VERY little experience with tubes but wanted see if you guys can confirm an opinion that a relative of mine has on the subject. I have heard that tubes perform on what I would describe as a bell curve. Basically he has said that Tube amps are a little rough at first but as the tubes age they seem to sound better and level out and finally, they start to drop off. He basically said they are like the brakes on a car. You may not notice that the performance of you brakes are fading until you replace the pads. This is why he has moved back to solid state. He said in his opinion, it is much more consistent. I believe that sound is generally subjective. What sounds wonderful to me may not sound great at all to you. Would the above description be accurate? |
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Post by pedrocols on Jun 4, 2015 13:52:05 GMT -5
Some people find LPs superior to CD or Flac files even with the pops and clicks. I understand this. I wasn't getting at what sounds better to who. I suppose rereading my post it may have sounded like an X vs. Y post. I was curious about if tubes perform in the described manner. Like I said, I have very little experience with tubes. I am however very interested in them and want to learn more from this thread. Yes. |
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Post by vneal on Jun 4, 2015 13:56:38 GMT -5
A watt is a watt is a watt.
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Post by KeithL on Jun 4, 2015 14:50:28 GMT -5
There are several factors that contribute to the way a tube power amp sounds...... Virtually all tube power amps have output transformers (all but a very few expensive and special ones). Output transformers tend to have several limitations: they tend to have less than perfectly flat frequency response, they tend to introduce phase shift, they tend to cause some other assorted types of distortion, and they tend to limit the damping factor (for a few reasons). Note that even small signal transformers have these limitations, but they tend to be less significant in small transformers; output transformers, because they have to handle lots of power and a wide range of frequencies, are a lot trickier. The tubes themselves also add some distortion - hopefully mostly the relatively benign second harmonic distortion that gives them their characteristic "sparkle" and "fluid midrange". In a normal design, the engineer would use feedback to minimize the distortion and frequency response issues, and increase the damping factor, but the phase shift of the transformer severely limits the amount of feedback that can be safely used. In contrast, a tube PREAMP is almost always capacitor coupled (and good coupling capacitors cause very few issues). This means that a tube preamp avoids most of the annoying issues caused by the necessity of using an output transformer. Also, since the circuitry in a preamp is running at relatively low "signal levels" rather than being asked to drive a heavy load (speakers), it inherently has less distortion in several other places throughout the circuitry. In fact, unlike a typical tube power amp, a good tube preamp can often have relatively low distortion - and be quite clean sounding, with just a tiny bit of pleasant "sparkle" and "fullness" added to the sound. To answer your question.... I would say that using a tube preamp with a solid state power amp is the perfect solution if you want "the best of both worlds". It is absolutely THE answer I recommend to people who are looking for "a little bit of tube sound" - but find that tube power amps add a little bit too much coloration to the sound - and remove a little too much heft from the wallet. The tube preamp will add a tiny bit of the coloration that we characterize as "good tube sound", and you can pick a preamp that offers just the sound you want; the solid state power amp will accurately amplify that tube sound and deliver it to your speakers, while still giving you the tight clean bass you just can't get from a tube amp (at least not with most speakers). Personally I find the low damping factor to be the single most significant "deal breaker" with tube power amps - other than the price. Note that there is a lot of variation in how tube preamps sound. Some sound almost indistinguishable from good solid state preamps, while others are deliberately designed to add lots of "tube coloration". The point is that, when you go this way, all you need to do is to find a good solid state power amp that is clean and accurate, them find a tube preamp that sounds exactly the way you want. (Rather than trying to find a combination of tube preamp and tube power amp that together add up to give you just the sound you want, you can simply find the preamp that sounds just the way you want it to, and combine it with a neutral power amp.) This is a very helpful discussion about amps. How about preamps--what is impact of a tube preamp when you are using a solid state amp, especially one with high damping. |
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Post by vcautokid on Jun 4, 2015 15:07:00 GMT -5
I agree, power IS power. Whether it is tubes, or solid state, nuclear, or coal.......
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Post by pedrocols on Jun 4, 2015 15:10:04 GMT -5
This is a very helpful discussion about amps. How about preamps--what is impact of a tube preamp when you are using a solid state amp, especially one with high damping. You can bypass the active preamp completely and go straight from source (DAC,CD player,etc..) with a passive preamp if the tube amp has high input impedance and sensitivity. I have tried both. I now use a tube amp and a passive preamp. What got me interested in tubes was listening to a tube preamp with solid state amp. I literally replaced my $4,000 tube preamp with a $60 DIY passive preamp. |
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