Digital ouput and volume.....

Audiophiliac,

At full volume or fixed output SONOS passes the digital stream unmodified. While it makes little sense to any analog units, the ZP80 digital connection will pass a DTS or Dolby Digital stream through to a digital input.

When you lower the volume, the digital stream must be modified. This will destroy the DTS and Dolby Digital signal, because the bit stream is modified and is no longer a valid DTS or Dolby Digital stream. With enough processor power, the streams could be decoded and rebuilt with lower volume levels, but since this is a stereo audio device, there is no point in adding that expense.

For the stereo audio signal, since we have a fixed number of bits to play with, some of the bits must be thrown away as the volume is lowered. Gradually, as the volume is lowered, the lower level information will be lost.

Which digital amplifier are you using? I'm not familiar with any digital power amplifiers amplifiers that don't have some sort of input level control.

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In the analog world, lowering the volume is not so hard on the music. The lower level information is gradually buried in the noise as the volume level is decreased. In the digital domain, the least significant bits are simply dropped. It would be possible to ease the digital degredation by use of "dither", but I don't know if SONOS is using this method.

I have 3 ZP80, 2 ZP100 and 2 controllers. I use itunes and ripp to apple lossless. 😃

In one room i have PMC Gb1 floorstanding loudspeakers powered by Electrocompaniet AW60 power amp connected with Kimber XLR to Electrocompaniet DAC1. The DAC is connected cia MIT coax cable to a ZP80.

I am using the ZP80s digital volume control and THE SOUND IS VERY GOOD!!!

After this discussion above i was a little bit concerned if the sound quality is reduced in my setup. I called Electrocompaniets service department and they confirmed that a digital volume control before the dac will recalculate the signal, but still my setup after the ZP80 is very "clean". If i add a preamp, i will need another analouge cabel and this will also affect the sound they said!

[SIZE="5"]Should i add a preamp or not????[/size]

I am using the ZP80s digital volume control and THE SOUND IS VERY GOOD!!!

I have an audiophile setup and also use the ZP80 digital volume control. I agree that the sound is very good. Since it sounds good, I decided the convenience of using the volume control on the hand-held controller far outweighs any agonizing about some lost bits when attenuating the volume.

But this does not negate the use of a good preamp. There's a misconception that adding another device to the signal path will degrade the sound, when in fact it can enhance the sound tremendously.

I use a very high gain preamp. The result is a much more open sound across the entire audio range and rock solid bass response with an amazing harmonic richness. I use the analogue outputs (heresy, I know!) of the ZP80 because I find that the high gain, quality output of the preamp renders other factors (such as the use of an external DAC and expensive interconnects) insignificant.

Others will disagree with me, but I alone know the truth. 😉 Trust me. You won't be disappointed.

I just checked the Electrocompaniet website. Their model EC 4.8 preamp puts out 30 volts. I bet that sucker sounds pretty good. Give it try.

I suprised that there aren't DACs with built-in volume controls.

As a cheap experiment, you could always build yourself a simple passive volume control using high-quality potentiometers, and see whether that sounds better than the digital volume.

But then, truth be told, I'm not too hot on electronics: I could never figure out why pre-amps had any other parts than an input selector and a potentiometer. Obviously, this would offer no features like balance or tone adjustments, and you'd have to manually turn down the volume when changing inputs, but this would seem to be the simplest, cleanest, pre-amp possible. Yet I've never seen such a beast.

Perhaps someone here knows why that wouldn't work?

jojohohanon,

"Passive" preamps are available in the marketplace. (usually from "high end" $ource$) Incorporating a balance control and a crude tone control are possible too.

Before these passive preamps came to market, I would build them in little boxes. They can be great problem solvers, but they can also cause trouble.

Simple volume controls of this type, high end or not, can introduce noise and control position related frequency response errors. These devices are much more sensitive to cable capacitance than active devices.

Ah!

So all (most) of the electronics in a simple pre-amp (and there does seem to be alot of bulk to even the simplest ones) is to equalize/cancel environmental factors like cable capacitance? cool! learn something every (other) day.

Hrm. I would have thought inductance to be more important in longer runs, tho I will admit to not having considered the balanced case, and in either case, I had assumed both quite negligible.

Could you prehaps point (or explain inline) to some explanations about how potentiometers might introduce frequency response errors? I had just assumed that high-end ones at lease were effectively just resistors with tunable resistance, perhaps in discrete steps, which I must admit I don't see affecting freq. response, capacitance, or inductance.

but then, I have already admitted to a poor grasp of elecronics (P=UI is as far as I got, along with maybe U=RI -- and not even sure about the last one), so I'm likely making bad assumptions somewheres.

A volume control is simply a resistor with a fixed contact at each end and a moving contact attached to the knob. A line level signal is applied across the ends with the "low" end connected to ground. When the volume control is at minimum, the "wiper" is effectively connected to ground and there is no output signal. At maximum volume the wiper is connected directly to the line in.

At mid rotation there is resistance between the wiper and ground and to line in. Part of this resistance is effectively in series between the line in and the volume control output.

Meanwhile, the cable has some capacitance. At higher frequencies, the capacitor begins to act as a low resistance shunt to ground. This high frequency shunt, combined with the series restance of the mid rotation control, begins to roll off the highs.

At maximum volume the low impedance line in swamps the cable capacitance and the highs return.

But wait, there is another drama: Since it is not at a temperature of absolute zero, every resistor is actually a noise generator. The noise voltage increases with temperature and resistance.

Returning to our volume control, when we are at minimum, the output is connected to ground, there is very little resistance and a very low noise voltage. At maximum rotation the outrput is connected to the low impedance line in and the noise voltage is both absorbed by the line in and swamped by the large signal. At mid rotation, the output noise is passed to the follow-on device.

Hence, there is a point near mid rotation of our passive volume control that maximizes noise and minimizes the high frequency response.

These effects are very easy to measure and often are not so hard to hear.

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The following experiment does not work on well designed equipment or units with electronic volume controls.

Insert a shorting plug into a line level input and switch to this input. In a VERY quiet room, rotate the volume control through its entire range while listening close to the speakers or with headphones. Surprise!! there is an increase in noise as the control is rotated through its center range.

Equipment reviewers are well aware of this little quirk. That's why they measure noise and frequency response at a preamp's full volume. (but they forgot to tell you exactly why they do that -- the numbers look better)

I have now added a high end preamp, Electrocompaniet EC 4.7 MK2, with 16 volt outoput, balanced (XLR) signal.

Its a huuuuuge different in the power of the ZP80 signal and the EC 4.7 preamp signal. With ZP80 i used to play with 75% volume, With the preamp i only use 25%!

It sounds like the music got more POWER and more/deeper bass. 🙂

Yes, it's amazing what high gain at the input of a power amp gives you...sounds like you got a good preamp!

At full volume or fixed output SONOS passes the digital stream unmodified. While it makes little sense to any analog units, the ZP80 digital connection will pass a DTS or Dolby Digital stream through to a digital input.


Buzz, is this a fact? Can I stream a DTS/DD-soundtrack from a dvd with the Sonos ZP-80? That would be great! 🙂
I do have the Classé SSP-30 and the Sonos ZP-80. Can I really get the DTS/DD-soundtrack in a folder? How do I do that? I know how to rip and copy a dvd, do I have to use the audio.ts now instead of the video.ts?
When I have a good music-dvd what I do now is this: rip it to the HDD, then make a WAV out of it with "AudioRipper", then in iTunes I convert it to AAC 320kbps.
A bit complex, isn't it?
It would be great to have the full DTS/DD-soundtrack available with the Sonos and the Classé homecinema system.
I do understand that I have to fix the volume....

Gr. Paul.