Why 2.1Vrms?

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#2
Early digital sources chose 2V RMS as the output standard, presumably in an attempt to preserve the wide dynamic range. This was in a world where people were more used to domestic line level being somewhere between 250mV and 600mV - there seemed to be no standard. The problem with this thinking is that 2V needs attenuating to go into a 300mV input so the dynamic range is immediately compromised.
 
#4
DF96 said:
Early digital sources chose 2V RMS as the output standard, presumably in an attempt to preserve the wide dynamic range. This was in a world where people were more used to domestic line level being somewhere between 250mV and 600mV - there seemed to be no standard. The problem with this thinking is that 2V needs attenuating to go into a 300mV input so the dynamic range is immediately compromised.
Click to expand...

This is why now preamps are not needed!!!

A Quote from the master Nelson Pass

Nelson Pass,
We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.
Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.


Cheers George
 
#5
George ...you are so wrong ... ( Pass also is wrong here )
The loss of dynamics and "mobile phone" sound in low listening levels is the issue with passive preamps ...impedance of in and out is also involved

If your conditions allow to play in moderate level all day you will be fine If you need 24/7 low listening level then the active preamp is a must

Key is the choice of gain less gain= less noise, now days preamps have far less gain to meet modern day sources

Noiseless preamp in comparison with a passive preamp simply doesn't exist so as always you have to give something to get something ...

Kind regards
Sakis
 
#7
Streten is correct here Sakis, so long as the source is around 2v and 200ohm output impedance or lower which most good ones are, the amp is 47kohm or higher input impedance, you can happily use a 10kohm passive pot.
Nelson is very correct in quoting.
"We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more. Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp."


Cheers George
 
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#8
My thinking is similar to DF96. The original CD standard was 16 bit which expands out 65536 (2 to the power 16). You could scale the required voltage output to any values you want but it seems logical to set a lower limit such that the smallest voltage level is not lost in noise. 2Vrms (say 6 volts pk/pk) means there are 32768 (65536/2) discrete levels available for voltages 'above' a notional zero point and 32768 for levels below, which give the smallest step change as 0.0000915 volts or 90uV. 65536 multiplied by 90uV brings us back to our chosen 6 volts pk/pk.

If we had said we wanted the output to be only 200 mv rms (or whatever) then the smallest levels would be lost in noise. I suspect it was all carefully considered at the time, and as with most things, a well chosen compromise was decided on.
 
#13
Possibly yes George , some of the very consumer amplifiers of the past like the Kenwood KA 5700 choose to go like that though they remember to increase the gain of the amp and design a transistor amplifier with input of above 100K

so its not a yes or no thing there is going to be variations opinions and use for many possibilities per amplifier

It remains though an issue ( NP and others may as well check search pages of the forum loads of members describing the problem the way i did ) that passive configurations is the cleanest available but will have in general bad dynamics in low listening levels always depending in the configuration and often even if impedance issues have been taken in mind ...

Regards
Sakis
 
#14
DF96 said:
Early digital sources chose 2V RMS as the output standard, presumably in an attempt to preserve the wide dynamic range. This was in a world where people were more used to domestic line level being somewhere between 250mV and 600mV - there seemed to be no standard. The problem with this thinking is that 2V needs attenuating to go into a 300mV input so the dynamic range is immediately compromised.
Click to expand...

I believe the intention was that the nominal level of a CD recording would be in the range of -12 dB FS to -20 dB FS. (I read that somewhere decades ago, but don't ask me where). The remaining 12 to 20 dB would then be headroom for short peaks. 2 V RMS for a full-scale sine wave then corresponds to 200 mV to 500 mV nominal level, similar to the nominal level of a 1980's cassette deck or a 5 mV nominal MM cartridge connected to a 100 times midband gain RIAA amplifier.

Unfortunately, in reality CDs were soon recorded as loud as possible and preferably even louder, especially on pop music. Hence the huge difference in volume between a CD and a 1980's cassette deck.
 
#15
While the most comfortable answer will be that listeners will find pleasure in both options The one will think its better to have dynamics and will not bother about distortion and noise And the other will think that the sound is clean and will not bother by any loss of dynamics .

Point is that opinions may vary as they like but here we are to discuss the technical side which should be based on reality and not affected on personal opinions.

Mr Np shares his opinion but produced the B1 especially made to match this problem So something doesn't match in the quote here ...
 
#16
MarcelvdG said:
I believe the intention was that the nominal level of a CD recording would be in the range of -12 dB FS to -20 dB FS. (I read that somewhere decades ago, but don't ask me where). The remaining 12 to 20 dB would then be headroom for short peaks.
Click to expand...


Would you mind explain more on "-12 dB FS to -20 dB FS"? What is FS? Is it Frequency of Sampling rate? And, why is there a remaining 12 to 20 dB headroom? Thanks.
 
#19
FS probably means Full Signal.
Sometimes referred to as 0dBfs, the maximum available from a digital source.

-12dBfs means 1/4 of the full signal, -20dB means 1/10th of the full signal.
One often finds that for music and audio signals that the average level is around 1/4 to 1/10 of the full signal, or stated the other way.
One finds that the peak signal is 4times to 10times the average signal.
 
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