Why some preamps does not play music? Cold?
I really dont think its possible to change that unlesss you DO change the preamp. I went through several until I found one that gave me what I was looking for ( great low end, excellent tone, great dynamics, and emotion and beauty) this was no easy task. It took a couple years and several hundred dollars to audition the 5 pre amps I choose from. (McIntosh, Prima Luna, BAT, Modwright, Manley Labs. Matt M |
mattmiller I didn't mean you, but was talking generally, for the future. I don't want dealers turn my thread into advertising platform as it i happening here every day. |
"Slow"... Hm... It is interesting... I’d say might be not exactly "slow", because it might have swing at the same time, but most likely wrong PRAT, that screws original melody, therefore depending on music played it varies from "Ok" to "bad". Hm.. Yep, thats probably it. In this case i guess there is no fix for that except for new preamp.((( |
Preamps can be system dependent and personal preference do apply as well as musical tastes, what sounds mediocre in one system may actually sound very good in another. You might want to start by trying different interconnects and or tubes. If in the end all else fails you might need to try another pre. Some preamps are more accurate then musical, maybe that's the case here. Preamps are very difficult to get right for manufacturers. |
dvavc, what's your tube preamp? Do you know the tubes in the preamp? You can tailor the sound by changing the tubes. |
P.S. Guys, this is pure technical question. I'm not asking which preamp does it all, so please no preamp recommendations!!! I just want to understand what is causing said phenomena, that is it.The reason a preamp may or may not be emotionally involving has usually to do with distortion. I'm not talking about a lot here either. Just a small amount of higher ordered harmonic distortion that is difficult to measure is easily heard by the human ear as brightness. This is because the human ear/brain system converts all forms of distortion into some sort of tonality. Higher ordered harmonics are an excellent example- and have a further complication with the human ear as the ear uses those harmonics to gauge how loud a sound is. So when they get messed with, the ear hears it as louder, harsher and brighter. Music is processed in the limbic centers of the brain. However, if the brain detects that there is something wrong somewhere, it has a tipping point wherein the music processing is transferred from the limbic centers to the cerebral cortex (where consciousness/intellect resides). When this happens, the emotional connection is lost. No more foot tapping, none of that feeling of wanting to dance. So what the designer of the electronics has to be aware of is what forms of distortion to which the brain is most sensitive, and avoid them through design. This is not really that hard if you understand engineering, what is hard is that you have to know the engineering and the physiology at the same time. One example of a design technique that causes a loss of emotional impact is the use of loop feedback in the circuit. Loop feedback, while overall suppressing distortion to a great degree, actually **adds** higher ordered harmonics to the signal. You already know the effect of that. But it does more- there are usually intermodulations at the point that the feedback is applied (the feedback node). These intermodulations may not have any musical relationship to the signal at all, at being at a low level, exist more as part of the noise floor of the preamp or amp. This has been known for the better part of 60 years (see Norman Crowhurst- he was writing about this in the 1950s). Now it happens that the ear has a masking principle- wherein the presence of a louder sound will mask the presence of a quieter sound (this is the basis of the encoding of mp3 files BTW). This is well-known. What is less well known is that there is an exception to the masking rule that has to do with hiss. This is likely evolutionary as wind and water make hissing sounds in the natural environment, and the inability to hear noises below the hiss might have profound survival aspects! So we can hear about 10-20 db into a natural hiss noise floor (the exact amount being a matter of the individual and also debate, but the 10db figure seems to be a solid). Now if the noise floor of the circuit is composed of harmonic and inharmonic (intermodulation) noise (as opposed to the hiss that arises from noise sources in the circuit unrelated to loop feedback), the result is that even though consciously we can't hear a lot of difference between the two noise floors, the unconscious portion of our brain (which is about 95% of the brain structure) can detect that something is wrong. When it does so, music processing is transfered to the cerebral cortex: the emotion connection is lost. Does that help with the understanding? Any questions? |
I, like Ralph, was going to cite distortion as the main culprit. I learned something new about how the brain processes music - limbic center vs. cerebral cortex. Thanks! Biasing the transistor or tube correctly is key to getting the correct sonics from the preamp. When switched on, the unit it cold & the bias is quite a bit off + it's still drifting. As the electronics warms up the bias establishes itself at the design point & also stabilizes i.e. stops drifting. This takes anywhere from 30-60 mins; sometimes/often more. For example, Wadia claims that their CDP sounds best after 72 hrs of continuous on. I can attest to this. After 72 hrs the entire tank-like unit is warm to the touch (vs. stone cold when 1st switched on). Tube amps too - most manuf say to not bother checking bias voltages for atleast 30 mins after turning unit on. Same deal with s.s. units. Besides stabilization of bias voltages & currents the 2nd aspect would be what the actual bias voltage & current is as set by the designer. Is the tube being run "low & hard" i.e. low bias voltage, high current OR the opposite - "high & soft" i.e. higher bias voltage, lower current. The bias point will tell in which region the device is operating in terms of output distortion, output impedance, gain, output noise. And, this will affect the sonics. Of course, there is no way to know this by simply popping off the top lid & peeking inside. A tete-a-tete conversation with the designer will reveal this info (& many manuf are cagey to reveal this proprietary info for a good reason). There are plenty of 6922 & 12AX7 tubes in the market but some preamps using them sound really good & others so blah... A 3rd possible reason is the quality of surrounding components - the resistors, signal capacitors, power supply capacitors, diode bridge rectifier, bypass caps, power supply snubber caps, grounding scheme, seperation of power supplies of the noisy output stage vs. the quieter input stage & the output impedance as higher output impedance has an interaction with the interconnect cable parasitic R, L, C + an interaction with the proceeding stage's input impedance that will affect sonics. For example, at one point a friend & I were messing around with a s.s. power amp's bridge rectifier circuit, power supply & bypass caps. Using a certain type of rectifier diodes + power supply caps + power supply bypass caps made the bass sound muddy compared to removing the bypass caps & using an even faster recovery Hexfred recitifier diode. All of these items affect sonics.... |
I appreciate the answers, didn’t even bargain for that deep level of technicality and psychiatry.))) I was hoping somebody just to say "go ahead re-solder this capacitor and everything will be OK". - that level of technicality) However, I’m afraid I didn’t express myself clearly enough and thereby mislead the public here). I have five preamps, but said issue persist only in one out of five. This one (tube pre), INHO is, the best (out of five) sounding preamp in terms of extensions, transparency, clarity etc. "Foot tapping" is also non-issue, i.e. plenty of that. However, as it most apparent on complex, avangarde jazz pieces (Kith Jarett, Jan Garbarek, Chick Corea etc.) it looses musical connection (?) It does it on any kind of music, but on regular music it is less obvious, because it still have enough "melody (?)" left to connect sounds into music(?). When switched to any other, out of 5 preamps, (cold, SS or whatever) which BTW, have less of extensions, clarity etc.,, the music comes back. So, the correct word is probably musicality not emotional engagement? I don’t really believe (for whatever it worth))) that any distortion has anything to do with this issue, cause like i said other preamps most likely have more distortions been not as clear and transparent as the one at issue.Just wanted to clarify the issue, to bring everybody onto the same page. |
All active preamps dvavc, have a colourations/distortion of their own, and all sound different to each other. None sound like the "mythical" "straight piece of wire". If you want to hear what your source sounds like without these active preamp colouration/distortions you should try to use your source into your poweramp via a passive preamp, the closest to a "straight piece of wire" sound. But for that to work it’s best the source output impedance should be low (1kohm/1000ohms or less) which most are. The passive pre should be a 10kohm passive, and the poweramp should be 33kohm or higher input impedance which most are. And interconnects from the passive pre to the poweramp should be 2mt or less and low capacitance (100pf per ft or less) which most good ones are. This then will give you the most uncoloured, dynamic way of hearing your source, you may not like it, but that is the sound of what your source is without any active preamp colourations/distortions changing the sources sound. If all parameters above meet the requirements try this. This is a $49 10kohm passive pre you can try, and even send back. And they have "B" stock as well. http://schiit.com/products/sys Cheers George |
If you want to hear what your source sounds like without these active preamp colouration/distortions you should try to use your source into your poweramp via a passive preamp, the closest to a "straight piece of wire" sound.I agree that all active preamps are colored to some degree or the other but I’m sorry I don’t agree with you that a passive pre is the proverbial "straight piece of wire". Very few setups that I’ve heard sound better with a passive pre; most of them sounded way better with an active pre (colored tho’ it might have been). There is one setup of a friend’s friend using a passive pre, Anthem power amp & small Magneplanar (not the 1.6 model, the one smaller than that, can’t remember the model #) that sounded oh-so-transparent. But it was simply superb for vocals, trios & small groups. Once you got some rock or blues or symphonic music going, everything just congested up. :( My brother’s set-up used a MFA passive pre that was built personally by Billington himself & used the ref-grade xformers. Super sound for many years that it gave him service. Then one day he was dissatisfied w/ the sonics & installed an active pre - OMG! even better sonics & he has not looked back....... |
However, as it most apparent on complex, avangarde jazz pieces (Kith Jarett, Jan Garbarek, Chick Corea etc.) it looses musical connection (?) It does it on any kind of music, but on regular music it is less obvious, because it still have enough "melody (?)" left to connect sounds into music(?). When switched to any other, out of 5 preamps, (cold, SS or whatever) which BTW, have less of extensions, clarity etc.,, the music comes back. So, the correct word is probably musicality not emotional engagement?Usually tubes have lower distortion (after all, they are quite linear). However, a lot depends on execution- and the tubes in the unit. You might have them tested for starters; a bad tube might do OK on simple material and might fall apart when things get complex. Other brands might work better too. Also there is the design of the line section itself- they are not all created equal and some are pretty bad- as George points out, they can be prone to colorations of their own (usually the distortions found in tube equipment are of the lower harmonics, which the ear converts to 'warmth'). But if there are design flaws all sorts of issues can crop up. I would start by getting the tubes tested! |
I tried different NIB tubes, both Sylvania though, while it did changed tonally, the issue complained about remained. I will try some other brand. However, it is 6sn7GTB therefore not to much choice to play with, unless try not GTB but that, as i understand, not recommended. Theoretically, are tubes in power supply might cause that? Guys, thanks for your time and thoughts. |
georgelofi, I thought we are all in understanding that "NO PREAMP RECOMMENDATION" on this thread. Moreover, if you read my responses you will learn that I already have 5 preamps, all of them are active, SS and tubes, but only one of them(tube) causing the issue which I’m trying to resolve here. This thread is not about "the best preamp". Moreover, been 20 years in this hobby I tried for a zillion times "strait wire" source to amp, as it was suggested here by many for many times, to be the best way. Guess what, i can’t stay that sound for more then 5minutes, because that sound is total chaos and mass, "all over", unbalanced and causes fatigue (in my ears at least) in 3 minutes. Once again, here, I’m trying to get an answer whether i can illuminate very specific issue in my otherwise favorite preamp. Thank you again for understanding. |
However, it is 6sn7GTB therefore not to much choice to play with, unless try not GTB but that, as i understand, not recommendedThere are plenty of 6SN7 types out there, and in a preamp I would expect that a GT, GTA or GTB could be used. You might want to check with the manufacturer on that. The big difference with the suffixes is how much voltage the tube can handle. 6SN7s, FWIW, are an excellent tube (the only bad ones being the modern Russian types) and so I would not expect that tube to be the issue, unless its microphonic or something like that. |
atmasfere: as a matter of fact, those Sylvania which i have currently installed are extremely microphonic. Are you suggesting it might cause the issue i'm talking about?yes! That very well could be your issue. Once I had a pair of 7308 tubes that were very microphonic & swapping them with a pair of non-microphonic 6922 made the sonics much better. While they lasted the Amperex 7308 very really superb. |
I don’t agree with you that a passive pre is the proverbial "straight piece of wire". I didn’t say it was, but it is closer than any active preamp can get. The only way to get closer is to go direct to poweramp with a source with one that has a digital domain volume control. But this way you have to use the digital domain volume control at or above 75% of full output,. If you don’t you start to what’s called "bit strip" that is loosing resolution from EG: 16bit to 14bit to 12bit. the lower you go below 75% of full volumme Cheers George |
