Thanks Atmasphere. Yes, I do see now what you were saying about a post-gain volume control affecting noise level. It attenuates the signal level, including the level of any noise in the signal.
Ssssh, is your tube preamp really that quiet?
Does anyone own, or know of, a tube preamp that is TRULY QUIET even when the volume is turned up? On my CAT tube preamp, there is always a certain amount of tube rush when the volume is up. This doesn't really bother me as it is not really audible when music is playing, BUT I'm sure the sound could be better IF this wasn't the case. Anyone have a totally quiet tube preamp?? No ssssh whatsoever!
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Why would a volume control (attenuator) after the gain stage affect the level of noise? Wouldn't that be true only of a volume control that is before the gain stage? Or have I somehow got this backwards in my head? I sense that I still have much to learn! You do have this backwards. Think about the volume control as a valve of sorts that lets the sound through the circuit. The circuit is going to make a fixed amount of noise. So if the volume control precedes the line stage it will have little effect on the noise of the line section. If it occurs after the line section the noise will be reduced as you reduce the setting of the control. The reason the latter is not done more often is that there is a price paid for having the volume control be the last thing the signal sees in the preamp- and that is that it can raise the output impedance substantially, and make the preamp highly susceptible to artifacts in the interconnect cable. So to allow the preamp to drive longer cables without artifact, and to be able to make bass easier into transistor amplifiers, most designers put the volume control at the input of the line section (which has the additional advantage of preventing overload of the line section by a strong input signal). Does this help your understanding? |
Hm.. To be true.. Realized after my last posting that I have not been quite fair to the Ref3.. The powerchord I use with my SS integrated is better and does make an obvious difference when it comes to create a darker background. The difference between the amps should be smaller to some grade than I experienced.. |
It is. Usually line stage noise is negligible unless you have speakers with high efficiency- 96 db or so and you may have to think about it. When loudspeakers get up to 104 or more, quite often the amplifier noise can be an issue too. With most line sections the position of the volume control has little to no effect on noise. But I do know of some where the volume control is post-gain stage (the Dude, for example); such line sections are affected by the volume control position. |
Err Ralph, when I started the thread, i was actually talking about both phono and line stages; however, it quickly became evident that the phono stage is more of a factor. BUT, I think that Tube Line stages seem to suffer from the same problems, perhaps less obviously so, but nonetheless not totally quiet at all volume levels with no input signal. Is that not a fact with all Tube Line stages as well? |
Tried out the Audio Research Reference 3 recently. The sound from drumheads, guitars, voices and liquid cymbals was wonderful! But eaven if the Ref3 is a great preamp famous for it's quietness compared to other tube preamps... there is some (eaven if it's little) grain in the soundpicture anyway. You must spend some good money on a powercleaner besides the mandatory good powercords I guess. Compared with the preamp in my SS Bladelius Thor III (which is not in the same priceclass), the Thor is much more quiet or black in the background and gives an impression of more 3D (but not detail!). And it's not a subtle difference! It's sad... The detailed, liquid sound from the Ref3 would be fantastic with a quiet background.. but maybe it's possible with a great powerfilter... I don't know.. I'm givin up the Ref3 and will try out a better dac-source for more soundstage, "blackness", clearer soundbodies, 3D and details instead. |
Hello Charles, the same thing happened to me although it was a different solid state preamp that I started with. We can get such good gain numbers with the use of stepup transformers that at normal listening levels, you can't hear the phono noise over that of the line section and amplifiers regardless of the loudspeaker. But I have yet to find a stepup transformer that conveys the music as well the tubes do running directly. Over the years we have experimented with semiconductors as well- super linear FETs and bipolar devices, and we have tried OP Amps as well. Try as I might, I can't get them to sound as musical as the tubes- I hear the same problems with the semiconductors in our stuff as I hear in the competition. So for the time being anyway, we are sticking with the tubes. They just work. |
Ralph, I discovered this some years ago when I owned a Symphonic Line SS amplifier and a tubed Audio Prism el 34 tubed amplifier. The S.Line amplifier was quieter in terms of external noise than the tube amp. Yet when comparing the same recordings via these two amps the tubes revealed nuance,subtle-inner detail and emotion that wasn't apparent with "quieter" amplifier. It was as if the noise floor of the tube amp became lower once there was signal propagation activation. I sold the Symphonic Line amplifier. Charles, |
A point that hasn't been mentioned yet is that our ears, or at least MY ears :-) are significantly more sensitive to high frequency hiss when it is firing into them from the side, rather than emanating from a direction that is closer to the one that is being faced (as it would be under normal listening conditions). FWIW I have never had a preamp in my system, tube or solid state, that was totally silent with my ear directly facing the tweeters from a distance of less than about 3 or 4 inches. That applies to both line-level and phono modes, and to any setting of the volume control, although the hiss level will of course increase somewhat in phono mode as the volume control setting approaches max. In my present system (solid state preamp), turning my head to face the tweeters, with my nose almost up against them, reduces that hiss level to being just about inaudible (except in phono mode with the volume control at or near max). As Rodman indicate earlier, though, some or most of that hiss may originate upstream, due to EMI/RFI pickup, ground loop effects, or source components. I know it is not being generated by the amp or its interconnects, because it disappears when the preamp is muted. 03-24-14: Charles1dadA couple of factors that may contribute to that in some cases, in addition to the performance characteristics of the particular equipment: 1)I've read a number of times in the past that the presence of very low level high frequency broadband noise can be subjectively perceived as an increase in ambience. That seems credible to me. 2)Just speculating, but perhaps a phenomenon can occur as a result of the addition of very low level high frequency noise to analog signals that is akin to the improvement in digital signal resolution which results from the addition of dither. Best regards, -- Al |
To all of those who are saying that their tube preamp is dead quiet, remember, we are not talking about normal use here. The OP is talking about his tube phono stage/line stage preamp, no signal, volume turned up, ear right next to the tweeter. In my first response I said my all tube preamp was very quiet, however, when turning the volume up and placing my ear within 2 inches of the tweeter, I can hear a hiss with no music playing. Of course this has nothing to do with listening to music, but this is what the topic of the post is about. Not tube line stages, or how it sounds from 8 feet away in between tracks, but 2 inches away with no signal. Try it, you may be surprised to find out that you do indeed have a hiss. Of course the hiss is meaningless, and has no bearing on enjoying music, but tubes do make noise. |
Phd, all active circuitry makes noise. Transformers are passive devices and don't make noise, but there is a price paid for their use as well. IOW there is no free lunch. IOW there is no curse :) I see the words 'dead silent' used a lot. I know that is not the case; as I mentioned before different people have different tolerances for noise. For those who think their all-tube system is dead silent on phono try this little test. Leave the tonearm on the tonearm rest. Set the source to phono and turn up the volume all the way. If you can then say that even with your ear pressed to the drivers of your loudspeakers that there is no hiss whatsoever then you have a good case for 'dead silent'. I think you will find though that you have no need to press your ear to the drivers- the noise will be quite evident. |
When I bought my Counterpoint SA1000, it was fairly quiet for a tube preamp, but over the years that my current, Golden Dragon matched 6922 which has been in the preamp for 22 yrs, has been exhibiting a slight whoosh which was not there let's say 4 or so years ago. However, any program material masks the background hash. Still, this tube sounds so good that I have never found another one to match it. At the rate it is going, maybe I will have to replace it in another 10 years. |
Trumweiller, please thank Ken from me. Ken's response was very illuminating and educational. I do agree that the noise from my CAT is quite minimal. I have rolled in tubes into both stages....NOS Mullards into the Line stage and NOS GE long plates into the phono stage Both sets were a nice upgrade to the stock Ei's. OTOH, the noise factor that we are discussing, has remained the same regardless of the tube used. As I stated earlier, the hiss ( noise) is NOT at all noticeable when music is playing. IF doing away with the noise ( or more of it, as I guess getting away from ALL of it isn't possible) also throws out the baby with the bath water....as Ken states; then I TOTALLY agree with Ken's decision to keep the current protocol. IMHO, the CAT preamps are STILL the best tube preamps that i have ever heard. Thanks again, Ken! |
Ralph, I had a Croft amp once designed for LOMC. It used parallel ECC88s and 24volt B+. It did have some tube hiss but worked well enough until any of the triode sections went microphonic. I tried swapping the psu for 2x12v lead acid batteries but it robbed the life out of it. On AC, it sounded great, notwithstanding the tube noise. |
I sent Ken Stevens this link so he could weigh in. Since heÂ’s not a member here, he asked me to post his response... "Thanks for sending this link to me. Let me attempt to illuminate this situation. The noise which ANY line stage produces at minimum volume is its natural noise level, determined by the noise threshold of the input device, be it tube or SS. I'm sure DaveyF can attest that his SL1 noise level is very tiny at minimum volume (and its about 6dB lower in current SL1s). When the volume control is raised, the line stage starts to amplify the noise from the input resistance. As the volume is raised, the input resistor becomes larger and the noise gets bigger, not because the amplifier's input device is getting noisier, but because a larger value input resistor simply produces more noise. At a certain resistance level of the VC the resistance noise of the VC equals the noise of the line stage itself, and above that point the noise becomes strictly dependent on the volume control level. No line stage of any type can produce a lower noise level once the noise of the VC itself becomes dominant. The SL1 line stage has a very low noise floor for ANY type of preamp, but once that VC starts going up there is nothing that ANY preamp can do to reduce the thermal noise of the VC (which is determined by the laws of physics). Therefore the only way that one can make a line stage quieter at gain is to lower the overall resistance of the VC. A 10k VC will have 1/5 the noise resistance of a 50k pot at any given attenuation level. Some preamps do indeed have low input impedance for this very reason, however these preamps are a tough load for most CD players, causing dynamic compression and introducing stress into the music. One of the biggest advantages of an active line stage is the fact that the higher input impedance vs a passive line stage allows the source to sound relaxed and dynamic. We aren't going to sacrifice one of the main advantages of an active line stage to reduce a noise which is basically inaudible in practice. Regarding phono stage input noise, this is different because ALL active phono input stages have noticeable noise when running a low output MC. The SL1 has the lowest input noise of any other tube phono stage, but there are some SS MC stages which are up to 6dB quieter, depending on particular input device. We refuse to use a SS input device because many of the benefits of a tube phono stage, including vibrancy, dynamic life, emotional expression, and timbral purity are compromised. In our current preamps we use an incredible MC transformer of our own design to improve the SN ratio by up to 17dB (in high gain mode) making it quieter than ANY SS or hybrid phono stage in the world. (Stereophile ran a test of the SL1 Renaissance which is online. Check out the incredible performance of the MC stage.) I hope this is helpful." Ken Stevens Convergent Audio Technology |
Interesting - my Veloce tubed preamp and phono stage are perfectly quiet no matter what the volume is turned up to. Prior to that, my VAC Renaissance preamp/phono stage was also dead quiet. The only time there was ANY noise whatsoever from either preamp was when a tube was starting to fail. Replace the tubes and back to the quiet! |
Very interesting thread because I hear the same ssssh sound from my tube preamp coming through my 102db efficient speakers. This noise is the same regardless of the preamp's volume setting. I have been able to reduce it substantially by turning the level controls down on the power amp. Changing out the tubes did nothing to eleviate this noise. The amp associated is a Class D switching amp. |
Ralph, thank you. I was beginning to believe that my tube phono section was faulty...same with the preamp. Particularly after reading some of the other posts on this thread. BUT, I kind of figured that some of these examples aren't all tube phono stages and IF they are, then the user isn't listening close to the speaker with the volume up and no music playing. I guess like everything in our hobby, there are trade-off's to be made. I'm still firmly in the tube camp though...particularly in the preamp stage. |
Manley Steelhead into Manley NeoClassic 250 monoblocks: dead quiet This is an example of a phono section that employs a semiconductor at its input, IOW, it is not all-tube. Ralph, is it possible to make a tubed phono section without a SUT that is noiseless? No. All circuits make noise (tube or solid state), the question is how much? You can get a tube phono section to be pretty quiet assuming the tubes are good (our phono section is good to about 0.2mV); anyone saying that their all-tube phono section is 'dead quiet', that sort of thing is not telling the whole story! If you are using a low output MC cartridge without a stepup transformer, there is going to be a limit as to how low output you can work with from the cartridge. For us that point is at about 0.2mV (0.2 millivolts), where if the preamp has good tubes in it, the phono noise will be below the surface noise of the LP. What I have found over the years is that everyone has different tolerance levels for noise. Some people are upset when they have the volume up way high, and then lift the arm off the record, and hear all this noise. But you know what? All phono sections that are all-tube are going to do that. If you run an SUT (its an option in our preamps) you can get the noise floor down to a point where it is near the same level as the line stage. That's pretty quiet! But if you turn the volume up real high, the noise is still there. What is happening is the transformer boosts the cartridge level so much that you just don't have to have the volume control up that high yet its playing at a very high level. So it makes the illusion that the phono section is silent. But no phono section is actually silent- they all make noise! |
I'm not sure that any high gain tube preamp and phono stage will sound completely quiet when the gain is turned up and there is no music playing. I have never heard such a piece. OTOH, I do agree that so long as the tube noise doesn't appear to be audible when music is playing, then there appears to be no problem and I also much prefer tubes over ss. However, I do wonder how much better the overall SQ, could and would be, IF no tube hiss was present whatsoever in the system. |
Are you saying that without an SUT, all tube phono preamps will solicit some tube hiss when the gain is turned up and no music is playing? Actually, all phono sections make noise. Tube units tend to make more, thus SUTs are more commonly used with tube phono sections. I personally find that tubes are more musical, so even though its harder to make them be quiet, I much prefer them to solid state phono sections. |
03-18-14: Charles1dad Thank you Charles. For the record, the hiss I heard was through the built in MC phono stage on my Cary preamp while listening to LP's. Just for fun, I just repeated this test through the line stage, volume up, no music playing. I could still hear a hiss when I put my ear right up to the tweeter. Again, I don't really know what purpose this serves. It seems like useless information to me, but there it is. Cheers, John |
Well I just put my ear right up to my speaker and sure enough I heard tube hiss from my Cary SLP-98P. I guess I'm not used to listening just for noise. I usually mute the preamp while changing sides on an LP. So I had to unmute it and put my ear right up next to the tweeter to hear the noise. It was inaudible more than a foot away. So yes, tubes are not as quiet as solid state, but I guess I always knew that. Tubes certainly sound better to me while the music is playing though. As long as I'm listening to music, and not listening for noise, I think I'll stay with tubes. |
I should add that I do crank my system up sometimes at very generous levels on quietly recorded acoustic Jazz trios, or with Shirley Horn for example:) There is never the slightest noise whatsoever between tracks or between discs. I have yet to try the built in phono stage, so that will be the better test. |
Ralph, that's interesting. I do use a fairly low output MC. However, I am hearing noise not when music is playing, BUT when it isn't. So, by lifting the arm of the record and increasing the gain, I do hear tube rush...which lead me to my OP. Are you saying that without an SUT, all tube phono preamps will solicit some tube hiss when the gain is turned up and no music is playing? BTW, in my case. the surface noise is louder than the dominant background noise....BUT I would think this still leads to a reduction in the "blackness" of the sound. |
No all-tube phono section is perfectly quiet. But a lot has to do with what cartridges it can work with and whether it has an SUT or not. If we use an SUT with our preamp the noise is not an issue with any cartridge. If no SUT then when you turn up the volume some hiss is audible. A surprising number of manufacturers that are otherwise all-tube will use a semiconductor as the first stage of gain. The real issue has to do with the surface noise on the LP. If the phono section is louder than the surface of the LP then you have a problem. If not, if the surface noise of the LP is the dominant background noise, you have no worries. |
In my instance, the tube noise is through my phono stage, however, the line stage also exhibits some noise. The tubes are rolled in NOS from Kevin at Upscale and are supposedly the lowest noise he stocks! They do sound great, BUT they are audible as the gain increases ( not as I stated with music playing). I'm really surprised that this isn't a factor with all tube preamps...particularly IF they include a phono stage and therefore are providing high gain. BTW, I used to own an ARC SP10Mk2 and the problem was even worse. Interesting that an SP16 is very quiet....perhaps that's due to the hybrid nature of the SP16?? |
I just purchased a Lector ZOE tube preamp. Dead quiet with stock tubes and I live in a high RFI area (one block from LAPD headquarters, 2 blocks from LA City Hall, cell repeaters within line of sight on the adjacent apt building). I had a lot of problems beforehand especially when playing vinyl and now my problems are gone. It also has a fantastic soundstage. |
When choosing tubes, for a pre or phono section; it's imperative to seek out those that are tested, and certified, for that purpose(Low Noise). Of course; your provider has to know how to properly screen valves. ie: Upscale Audio ( https://www.upscaleaudio.com/pages/Testing-Small-Signal- Tubes.html ) However; when you crank your volume to full, the pre might not only let you hear tube microphonics, but anything that interconnects, or empty inputs, may be picking up(ie: EMI/RFI). If there's a phono section ahead of it; it's noise is amplified/compounded. |
