I did not say they result in increased noise floor. EVery component has a baseline noise floor. I was describing how the smallest voltage details rise from the thermal noise floor as the voltage division (as the wiper moves or the ladder is varying) result increases. In 99% of preamps on the market the line level signal from the source fisrt meets the passive volume control (potentiometer, TVC, ladder what have you) and then it hits the constant/fixed gain stage (6 dB, 12 dB, 18 dB whatever)
There IS NO GETTING AROUND thermal Johnson noise (that is)physically inherent in every resistor device in the known universe.
There is a sweet spot and it does have everything to do with optimizing the dynamic range and your overall system "sensitivity"
Dave Mitchell: The ARC devices use a digital potentiometer (a plastic case 5 volt IC) that depending on the digital (bit level) value switch in series internal resistors...it is identical in fundamental operation to stepped attenuators. Except in the IC the signal ALSO flows though active devices (multiplexors and buffers). Pick your poison.
|
A resistor ladder does nothing different than a potentiometer. It just does it more precisely (assuming high quality components and design.)
Think of it this way. A pot or ladder simply dumps part of the signal overboard. The earlier description of a preamp with no volume control being at full blast is correct.
Volume attenuation devices can also be placed at different spots in the gain stages of a preamp circuit. They do not automatically result in an increase in noise floor or a decrease in dynamic range. |
Wow; didn't expect so many great answers.
I really don't listen very loud, normally. Probably 90-95 db would be the norm (peaks at these levels).
Thanks!!!! |
Thanks Davemitchell, I finally understand the mystery of volume control settings and why there use to be a "sweet spot". |
Sugarbrie is correct. Your preamplifier's natural state would be to have the volume control all the way up. Any setting lower than that is attenuating the output from where it wants to be.
The position of the volume control is also meaningless. Where you end up is a function of the relationship between the source/signal you are listening to and the preamp's gain combined with amplifier and speaker sensitivity. Volume position can be radically different for each source. For example: if you have a low output MC phono cartridge (as I do) you may find that on some records you can "peg" your preamp's volume without getting as loud as you would like. And that is perfectly fine.
With older preamps that use a potentiometer for volume control, the higher up the pot, the better the sound because the pot is an impediment in the signal path and at higher settings you are listening to less of the pot. Many modern preamps (like the ARC SP16 mentioned) no longer have a pot in the signal path, but instead use a reistor network or ladder that provides nearly identical performance at any volume setting. |
If grey colored snot starts dripping out of your ears or nose, then your volume level is too high...your brain has just had a meltdown :-) |
Ryder,
I assume you mean 75-80 dB SPL with C weighting and ballistics set to slow. I find that a nice setting if I'm really listening, but I prefer 10 dB lower when I'm at my computer or reading.
A look at A weighting, a scale that attempts to incorporate hearing sensitity, shows that we perceive more at each end of the frequency spectrum, especially lower frequencies, as level is raised, yielding a better balanced sound. Many older receivers and some preamps had a loudness switch that contoured the sound as level was lowered to compensate for hearing sensitivity, usually on the basis of the Fletcher-Munson curves.
db |
You need to think of volume in reverse. If you bypassed the volume control you would get loud full blast unrestricted sound. A lot of people would assume no sound. When you have no sound coming out, the volume control is actually on full. All a volume control does is attenuates the output of the preamp.
Everything is system dependent. The person who wants to have crystal clear blasted rock and roll is not going to build the same system as the person who wants crystal clear jazz played softly as background music. |
I cannot turn the volume knob on my previous Plinius preamp past 10 o'clock or I'll destroy my ears(or burn something). I have the volume knob on my current ARC LS-16 preamp at 2 o'clock when I blast the system, well for just a short period of time of course.
Just use an SPL meter and measure the sound levels you're getting. Recommended is at 75-80db if I'm not mistaken. Listening at over 100db for prolonged hours is not recommended. |
it's more a dynamic range issue. While said tracking differences may be an issue, I have yet to hear any preamp suffer from this effect (ie enough channel imbalance to notice center fill shifting)..that would have to be one hideous potentiometer!!!!
when you rotate the vol knob from zero sound on up you are raising the smallest parts of the signal out of the noise floor. When you do this you are increasing the dynamic range; those subtle signals give rise to microdynamic expression... ( in preamps we are paying dearly for signal attenuation and very low noise floor, if you want neutrality...if you want coloration this-ish PLUS something else)... I firmly believe this is the essence of "sweet spot". It is system dependent as others have mentioned (amp, speaker sensitivity, overall system resolution)...
I notice that my sweet spot moves to the right for every pint consumed, YMMV. TGIF! |
There is no magic "o clock". All volume circuits would have to be identical in all gear. Actually, everyone would have to have identical systems.
At what volume your speakers perform best is a more likely determinant.
Same for your amplifier's output. |
Actually, the issue isn't channel separation in a volume control but rather tracking between the left and right channels. Mass production potentiometers tend to track more unevenly at lower settings. If your knob runs from 7 o'clock (vol all the way down) to 5 o'clock (vol all the way up), knob settings at 8 or 9 o'clock will probably have more imbalance in volume between left and right than an 11 o'clock or higher setting.
Many high end preamps use higher precision pots that help eliminate this problem, but you'll get a ability to control your volume more precisely if your typical listing settings are in the middle to upper range of the knob.
As long as you are not overdriving things (and you will hear distortion or an unreasonable volume if you are) there is no problem in having a volume knob set too high. |
Thanks Arthur; I just needed someone to say that :) |
No, there is no problem - other than a psychological one. :) Just turn it up and enjoy the music.
Incidentally, it is true that many volume controls have better channel separation at the top end of their range so you might even be better off with a low gain preamp!
Arthur |
