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Volume controls, pre amps, power amps, analogue, digital, etc.

Yorkshire Mouth

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Well, I've read a few threads here, and I'm still not sure what's what.

I'd like to ask for the forum's expertise, both generally and specifically.

First, the general. My (current) understanding is that, all else being equal, in an analogue set up, volume should be controlled by the pre amp, and power amps left set to full. Some power amps have volume controls, and some of these have 'power amp mode' switches, and these bypass the attenuation in the volume control, effectively setting it to full.

The implication here is that, at anything other than full power on the power amp, there is some lowering of quality (however slight).

So firstly, is that correct?

Secondly, I understand DACs with digital volume controls, and by implication digital pre amps, should be set to full, as lowering it reduced the dynamic range in the digital signal (however slight).

So secondly, is that correct?

Thirdly, if both of the above are true, which does least 'damage'? Setting the amp to full, and using the volume control on the digital device, or vice versa?

Now the specific.

My set up will be a WiiM Ultra Digital Streaming Pre Amp, which has a digital volume control. It will feed a Topping PA5 II Power Amp.

The volume must be controlled by the Ultra, as it has a sub out; using the Ultras volume control is the only way to control the volume on your sub and mains simultaneously.

Options:

1 - Set the volume on the amp to full power, then set and adjust the volume on the Ultra as necessary.
2 - Set both as high as possible, reducing both equally to a useable level.
3 - Set the Ultra to maximum volume, set the amp to low. Play a very loud piece of music - the loudest I'll ever play. Turn the amp up until it hits the loudest I'll ever listen. Then turn down the Ultra, and leave the amp at that level all of the time.

Comments, suggestions, corrections, etc.?

Many thanks.
 
You would need your own measurements to find out exactly,but here's all the principles:

 
Interesting question, it does seem more complicated than it should be. I don't have an answer.

I do have a 4th option for consideration - any value in adding a passive volume control between WiiM and Sub/Amp?
That would allow the WiiM to sit at full output, while protecting your speakers from 'unexpected digital surges' (rare, but spoken about here)
 
Interesting question, it does seem more complicated than it should be. I don't have an answer.

I do have a 4th option for consideration - any value in adding a passive volume control between WiiM and Sub/Amp?
That would allow the WiiM to sit at full output, while protecting your speakers from 'unexpected digital surges' (rare, but spoken about here)

I have considered that. Unfortunately, that would introduce the issue of the comparative volume of the sub.
 
You would need your own measurements to find out exactly,but here's all the principles:


Quite comprehensive.

It suggests having more detailed knowledge of each component than I’m ever likely to have, and applying those measurements to calculations I’m ill-equipped to make.

So, any general advice?

A very basic reading. We appear to be looking at a pay-off, a balancing act, between distortion and SNR. I believe that both the DAC (presuming the Ultra lives up to previous WiiM kit), and PA5 (as measured by Amir), have, or will have, very low distortion, and SNR. I suspect - given my very limited understanding - that I’d have to behave in quite extreme ways to introduce audible distortion into this set up.

So SNR is likely to be more of an issue, and to maximise that, I’m probably better off keeping the Ultra’s output as high as possible.

Any merit in that approach, or have I misunderstood?

And finally, if I were to get this the wrong way around, how large are the differences likely to be?
 
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I have considered that. Unfortunately, that would introduce the issue of the comparative volume of the sub.
I install I fixed attenuator in front of my Buckeye amp, mostly for protection purposes, run the SMSL DAC at max and do volume adjustment at the Wiim Pro Plus which is typically at 80-90 for normal listening with the attenuator and Roon headroom adjustment in place. DAC output passes through a pair of powered JBL subs with balanced output with high pass filter to the Buckeye.
 
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Quite comprehensive.

It suggests having more detailed knowledge of each component than I’m ever likely to have, and applying those measurements to calculations I’m ill-equipped to make.

So, any general advice?

A very basic reading. We appear to be looking at a pay-off, a balancing act, between distortion and SNR. I believe that both the DAC (presuming the Ultra lives up to previous WiiM kit), and PA5 (as measured by Amir), have, or will have, very low distortion, and SNR. I suspect - given my very limited understanding - that I’d have to behave in quite extreme ways to introduce audible distortion into this set up.

So SNR is likely to be more of an issue, and to maximise that, I’m probably better off keeping the Ultra’s output as high as possible.

Any merit in that approach, or have I misunderstood?

And finally, if I were to get this the wrong way around, how large are the differences likely to be?
Given the measurements we have at hand I would worry only about safety issues so I would include a scheme that covers incidents like level shooting up to 0dB,etc.
Also I would check input/output impedance for a good ratio.
 
So, any general advice?
If you don't have any problems don't worry about it... ;)

The general rule is - Keep a hot signal throughout the chain for the best signal-to-noise ratio and attenuate at the latest opportunity to reduce the signal and noise together. But that's not always practical or convenient. Your preamp may have a remote control and your power amp may not, etc.

Lowering the volume in the digital domain lowers the resolution (you aren't using all of the bits) but as an "everyday volume control" it's OK because you can't hear the loss of quality unless you re-amplify... You generally don't want to be attenuating digitally when listening at full-maximum volume. (Something similar happens with analog attenuation and re-amplification.)

A very basic reading. We appear to be looking at a pay-off, a balancing act, between distortion and SNR.
Distortion isn't likely to be a problem unless something is Clipping. You won't clip your DAC unless you boost or EQ in the digital domain,* and most preamps (and other analog line-level signals) usually have tons of headroom so they are not likely to clip.




* The original digital data can also be clipped, but lowering the volume (digital or analog) won't fix that.
 
I use one of these for easy attenuation of my front L/R channels from my AVR. Two outputs, so you could use one for a sub.

I’ve not never missed seeing that before!

Great solution.

The issue would be, I suppose, this. That device, even if it’s a hugely audiophile, and statistically superb, would introduce at least a little extra noise and distortion, even if that were very low.

So that needs to be balanced against any distortion and noise introducing by having either the Ultra or PA5 II at less than full volume.
 
General advice?

To simplify it even further my suggestion is to turn power amp down to zero and all your preceding digital stages at max. Then play something loud and turn up the power amp to the loudest you want to listen to music. Then leave the amp set where it is, even tape the knob if you have little fingers about, and do your music level control somewhere else in the chain wherever is most convenient. If it's an even choice in convenience between control on the streamer or the DAC do it, as suggested above by DVDdoug, as late in the signal chain as possible so as to keep the signal hot.

Doing the above protects you from melting something with an accidental 0db signal, gives you good convenience, and will be close to the optimum you can achieve no matter how much maths you do.
 
I've done 1 & 3. Both work but I see no real reason here to consider anything than 1.
Digital volume hasn't been a problem for a decade. Noise and distortion are so low that they make no difference here, not even close, however you do this. So might as well do it "normally".
 
General advice. 1) always avoid overloading the input of a device; THEN 2), think about noise and the least significant bits of the bitstream.

When you turn down an analogue potentiometer, you reduce the incoming peaks, BUT you also attenuate the incoming noise. This can be very advantagous.

When DACs could only do "volume control" by reducing the bit depth, an analogue control after it was preferable. Now that volume control is done in the DSP part of the DAC chip using floating point maths and maximum bit depth, the arguments against DAC volume control go away (increased noise or reduced bit-depth). The risk is still that the DAC may accidentally jump to 100% (its default) and blow your speakers and hearing.

So, in general, try and keep the level as high as possible from the start of the chain onwards but ensure you don't overload each following device (leave some headroom). Attenuate at the last stage you can. Be aware of protection against a DAC blip. If you have sensible attenuators in your power amplifier, set the preceding chain has high as possible (avoiding overload) with the power amp pots set to 0 then slowly increase then until it's as loud as you want. Then leave those pots there and attenuate further down the chain.

To do all this, you need to know about the maximum output of each device in the chain and the sensitivity or peak level each input of the chain.
 
I fooled around with this when I was figuring out what I wanted and my system bits and pieces.

I had Bluesound Node, Naim 5i integrated, sub and a turntable.

Bluesound has a streamer and adjustable xo for a sub. Connecting sub to Naim would have been a weird move - from dsp to old school, not going to happen. Connecting tt to Naim was better as Bluesound analog input is not very good. Naim is not very good at low volume and Bluesound is pretty hot like all modern stuff.

So I compromised and set Naim volume to nice operating range. Connected tt to Bluesound as my tt is just a secondary source after all and with bog normal Ortofon 170€ cart. Now Bluesound controlled all the inputs, sub and volume. It has very good digital control and I could not perceive any ill effects even at low volume.

But this was out of momentary need, not something I'd consider otherwise, and Naim is very old school gear. You only have a preamp/streamer and a power amp, both very modern, so I don't see much to optimize here. For longer chain where you have to think about gains it's a different matter.
 
I've found the article Gain Staging Like a Pro from Sweetwater—especially the visuals near the end—to be very helpful in understanding how noise floor is increased or decreased based on where gain is being added in the audio chain. Obviously, other factors such as the SINAD quality of each device comes to play... as well as any places were the system itself is also doing DA/AD cycles or DSP alterations need to then be considered.

Prior to reading that article (and getting some kindly correction from a fellow ARS contributor), I was under the impression the best approach was to incrementally boost gain in a step-ladder fashion along the audio chain; where each component contributed "clean" moderate boosts to achieve the end volume.

 
Well, I've read a few threads here, and I'm still not sure what's what.

I'd like to ask for the forum's expertise, both generally and specifically.

First, the general. My (current) understanding is that, all else being equal, in an analogue set up, volume should be controlled by the pre amp, and power amps left set to full. Some power amps have volume controls, and some of these have 'power amp mode' switches, and these bypass the attenuation in the volume control, effectively setting it to full.

The implication here is that, at anything other than full power on the power amp, there is some lowering of quality (however slight).

So firstly, is that correct?

Secondly, I understand DACs with digital volume controls, and by implication digital pre amps, should be set to full, as lowering it reduced the dynamic range in the digital signal (however slight).

So secondly, is that correct?

Thirdly, if both of the above are true, which does least 'damage'? Setting the amp to full, and using the volume control on the digital device, or vice versa?

Now the specific.

My set up will be a WiiM Ultra Digital Streaming Pre Amp, which has a digital volume control. It will feed a Topping PA5 II Power Amp.

The volume must be controlled by the Ultra, as it has a sub out; using the Ultras volume control is the only way to control the volume on your sub and mains simultaneously.

Options:

1 - Set the volume on the amp to full power, then set and adjust the volume on the Ultra as necessary.
2 - Set both as high as possible, reducing both equally to a useable level.
3 - Set the Ultra to maximum volume, set the amp to low. Play a very loud piece of music - the loudest I'll ever play. Turn the amp up until it hits the loudest I'll ever listen. Then turn down the Ultra, and leave the amp at that level all of the time.

Comments, suggestions, corrections, etc.?

Many thanks.
I would do 3 if other people have access to the pre volume to protect your speakers. Otherwise 1. I doubt you will hear any difference anyway except maybe hiss level. And 3 is usually the best for his.
 
In my PC-DSP-based multichannel multichannel-DAC multi-amplifier multi-SP-driver audio setup, the "master volume" is controlled by the most upstream music player software JRiver MC32.

So, where can I control relative gains among L&R active-subwoofers (SWs), woofers (WOs), midrange-drivers (MDs), tweeters (TWs), super-tweeters (STs), all of them are directly and dedicatedly driven by separate amplifiers?

I can "do it" either or combination of;

1. VB-AUDIO MATRIX's Routing Grid cells,
2. DSP-EKIO's I/O control panels (actually I have 10-channel out),
3. multichannel DAC OKTO DAC8PRO's 8-channel output gain controller,
4. each of the four integrated amplifier (or four preamplifiers, if you like to do so) driving WOs, MDs, TWs and STs, as well as volume(gain) controller of SWs.

I usually keep 1. 2. and 3. in "untouchable" fixed gain; i.e. all 0 dB in 1., certain fixed above 0 dB gains in 2., and all -4 dB in 3., respectively.
(We should never change them "on-the-fly while listening to music" for safety concerns!)

Then why do I (should we) keep safe and flexible relative gain (tonality) control in analog domain (4. above)?? What would be the merits/pros and rationales with 4.?

You would please find the answers in detail in my recent post here;
The latest system setup of my DSP-based multichannel multi-SP-driver multi-amplifier fully active audio rig, including updated startup/ignition sequences and shutdown sequences: as of June 26, 2024: #931
In my post #931, I wrote as follows;
******************************************************
Here in this post, please let me emphasize again about the pros and merits of relative gain (i.e. tone) control not only in digital domain but also in analog domain using pre-amplifiers or integrated-amplifiers (in my setup). I recently wrote again in my post #56 on a remote thread like these;
Yes, as for safe and flexible tone controls (or I can say "relative gain controls among the multiple SP drivers"), my stance (policy) at least, is that we are encouraged to utilize the "best combination" of "DSP configuration in digital domain" and "analog domain tone controls using HiFi-grade preamplifiers and/or integrated amplifiers".

We need to note (and to respect for) that analog domain tone controls (relative gain controls among the multiple SP drivers) give no effect nor influence at all on the upstream DSP configuration (XO/EQ/Gain/Phase/Polarity/Group-Delay). I believe that this is a great merit of flexible tone controls in analog domain. We know well, on the other hand, in case if we would like to do the "tone/gain controls" only within DSP configurations, such DSP gain controls always affect more-or-less on "XO" "EQ" "phase" and "delay" of the DSP settings which will leads you to possible endless DSP tuning spirals every time; within DSP configurations, XO EQ Gain Phase and Delay are always not independent with each other, but they are always interdependent/on-interaction.

Just for your possible reference, my DSP-based multichannel multi-SP-driver multi-amplifier active system has flexible and safe analog level on-the-fly relative gain controls (in addition to upstream on-the-fly DSP gain controls) for L&R subwoofers, woofers, midrange-squawkers, tweeters, and super-tweeters, all independently and remotely. My post here shows you a typical example case for such safe and flexible on-the-fly analog-level tone controls. This my post would be also of your interest.

Of course, I know well that I (we) can also perform such relative gain control using DAC8PRO’s 8-channel output gain controllers. I do not like, however, to change the DAC8PRO’s output levels frequently on-the-fly (while listening to music) due to safety and inconvenience concerns; I like to keep DAC8PRO’s analog out gain level always at constant -4 dB which should remain to be usually “untouchable” in my case.

One of the very unique aspects/features of my multichannel audio rig is that I fully utilize four HiFi-grade “integrated amplifiers” plus L&R active subwoofers, each of them have its own gain (volume) controller for safe and flexible relative gain (tone) control in analog domain even on-the-fly i.e. while listening to music.

In this perspective, my posts #438 and #643 should also give you better understandings. Furthermore, my posts #317(remote thread), #313(remote thread) would be also of your reference and interest.

Fig03_WS00007533.JPG


Fig08_WS00007528.JPG

******************************************************

Edit: (10:45 AM July 13 2024 Japan Std. Time) _____I added two diagrams under the above Spoiler cover.
 
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