Super-sensitive volume controls - remedy?

One of the bigger problems faced by preamplifier manufacturers is that when Sony and Phillips got together and created the Redbook specification, they really had no clue as to what they were up to.

As a result, they set the digital audio output spec at 4 volts! Why do I say they had no clue?? Because its obvious they never looked at amplifier specs, to find out that no amplifier ever made has needed 4 volts for full output.

There was also an assumption that no-one would ever want to listen to tape, tuner, phono or any other source other than digital. The result is that you have to knock the digital source signal down in order to use it. Passive can kinda sorta work in this regard but have problems, attenuators can kinda sorta work but have problems and active preamps can kinda sorta work but have problems.

If you want to get to the bottom of this, complain to whomever made your digital source! They need to set the output to something a little more reasonable- 2 volts would help and 1 volt (which was the old analog standard) would be great.

We've been building our volume controls in our preamps so that the first few steps are fairly close together to help get around this problem. We can also build our preamps so that the line section has no gain but still buffers the volume control and can still control the interconnect cable to eliminate cable artifacts. But this too is an imperfect solution. In a world where you have some amps with anywhere from 15 to 50 db of gain and speakers that are anywhere from 84 db to 104 db, there are going to be problems!!

Now, much more so than back the 1970s or 1980s, equipment matching is a serious issue.

I understand what you're getting at, Atmasphere, but even back in the 70's and 80's I don't recall using any source that required turning the volume pot up much past 12:00 on any amp I ever owned. Of course, I have forgotten a lot of things about those days! Maybe direct from a tape head?

I may be missing some important electronic principle or oversimplifying things, but it seems that the maximum gain of a preamp could be lowered while using more of the volume pot to accommodate a wider range of output voltages from the various sources.

As far as I remember the Redbook standard has always been 2v.
Just look at the first players from Sony/Marantz/Philips.
EG: Sony CDP-101 Marantz CD-73 etc.
They all have 2v output spec, which is all that's needed to drive the majority of poweramps from yesteryear or today into clipping.

All this gain with preamps today, is a left over from the days of vinyl with low gain phono, step ups, and head amps, when you needed some extra gain.

Today digital sources, including phono stages have 2v and over output and that's all needed with a passive pre or unity gain buffer to send an amplifier into full clipping, so why the extra gain??

I keep coming back to Nelson Pass's statement below.

"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

Thanks for pointing that out George. Funny thing though, we see 4 volts and more all the time, of course we get a lot of balanced line DACs and CDPs used with our stuff, which may explain the disparity.

Almarg - I bought the Rothwells to help achieve a more common volume control setting for CD to match with the Aria preamp's built-in phono stage. I tried the Rothwells on the preamp's CD input. This helped a lot to bring the CD closer to the phono's ideal listening level near the volume control's 12 o'clock setting but the result was disaster …. and out came the Rothwells.