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Oppo 205 Volume Setting - Fixed vs Variable for 2ch Processing


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Hey all,

I've posted this here as it is relatated to the Oppo 205 but more so its 2ch Audio functions.  Hopefully there are some useres out there that can chime in. If it needs to be moved to another thread area please feel free.

 

The volume setting in the Oppo Audio Processing for 2ch is set at "fixed" which is 100 on it's  scale.  I have read that each step decrease is .05db and if you are experiencing clipping (which i am not) to lower it by 2-3db which at half steps will be down to 94 on the volume scale.
 

I further read a long article talking about its dynamic range and noise floor if plugging into a power amp where by you can safely run it down to 70 for example with no sound degradation, however, mine is plugged into my Integrated Amp so not sure if the relevance is the same.

I have found at volume fixed at 100 its considerably in your face and IMO a little bright, but when i lower the volume to 84 (to be exact) it seems to line level with my iPod doc and also pretty close to the Vinyl output volume, but more so things are sounding sweeter.  When i turn the amp up it still sounds really nice, but at 100 if i turn it up i find it fatiguing very quickly? 

note: my ipod doc is the project digital S and strips the file from the iPod so bypasses its DAC and uses its own or the Oppo's - whichever I choose.

 

By the details provided that means at volume level 84 in the oppo I am lowering the volume by 8db, it should not effect the dynamic range or noise floor any as its well with in range BUT given its plugged into an integrated amp NOT a power amp it also seems alot lower than suggested.

 

I've got the Oppo set to stereo down mix mode so its configured correctly for the 2ch audio out option and using the dedicated stereo RCA outs.

 

Am i losing anything in the music by doing this?

 

I know there are no steadfast rules with this stuff but i am interested in any other experiences with this.  i dont have a nother CD player to use as a comparison but its intriguing me that

1.) the volume at 100 is so much louder than all other componants plugged into the same amp and

2.) lowering the volume by 8db through the Oppo smoothes out any brightness etc even when i really crank the amp?

 

Has anyone else toyed with this option or experienced similar?

cheers.

 

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thanks mate!  This looks a great read and i'll read through this today - much appreciated.

 

Once the attenuators arrive are you happy to post your findings? If so that would also be great to read up on your outcome.

 

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The oppo 205 has an output standard  when set on 100 of 2Vrms at the RCA (unbalanced output)

You need to check the input spec of the amplifier you are using as some will have a 1vrms and can be severely overloaded.  

Cheapest suggestion  is to reduce the volume to cater, failing that you’ll need attenuators as one has already advised. 

 

https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-oppo-udp-205-uhd-player.3660/page-2

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Just read through the post, great read, i dont think my issue is as extreme as what you are experiencing, mine is probably more my fussiness and could be in part to the Sabre Dacs as they are "said" to have a brighter sound. Possibly lowering the Oppo volume reduces the push from the Oppo to my amp.  I checked the technical spec and there does not seem to be any mismatch between their output and inputs.

 

All that aside the attenuators seem a good thing, one question i have though, how is implementing the attenuator into a system different to reducing the volume on the Oppo?  If you add a -10 attenuator isnt that the same as making the volume on the Oppo 80? 
 

Is it because it allows the full range of the Oppo be used and then the attenuator acts as a gain control prior to the integrated amp as opposed to lowering things from the output of the Oppo?

 

Oppo have stated that there is plenty of headroom/dynamic range and noise floor wont be affected even at level 40. (see cut and paste below - purely aimed at power amp but i cannot see how the principle is any different for a power amp, pre amp or integrated amp)

 

I had Gatti Audio update my stereo capacitors on the unbalanced line, and to be fair prob havent given them much time to burn in (i know that is also a contentious issue) but none the less the attenuator has appeal from the view that the volume at 84 for example sounds a tad more sweet and soft as opposed to the in your face fixed volume of 100.

 

very keen to hear you go once the attenuators are in place!!

 

I also noticed you can buy the attenuators for the source or standard, due to space the source option might work well for me.  They should have no different effect on the performance which componant they are plugged into i'd think?

 

https://www.ebay.com.au/itm/Rothwell-RCA-In-Line-Attenuators-Pair-10dB-For-Source/292463759687?epid=1473142486&hash=item441832d147:g:eCoAAOSw0d1cBQ5x

 

Connecting the 205 Directly to a Power Amp -- Part 2

In my post above I talked about "impedance" considerations in connecting the Analog outs of the OPPO UDP-205 directly to a Power Amp -- no pre-amp in between. Now I want to talk about Volume.

A key difference in connecting directly to a Power Amp is that the Amp is not likely to offer Volume control -- or call it "Gain" control. That means you will be relying on the Analog output Volume control provided by the 205 itself.

Power Amps have different "Gain" characteristics, and if the Gain of the Amp is too large (and your speakers too "efficient") you will need to use a very low Volume setting in the OPPO to achieve a comfortable listening level. That raises the question whether a low Volume setting in the OPPO affects the audio quality. And if so, how low is TOO low?

For folks new to this, an important concept here is that the Volume control in a device like the OPPO does not "amplify" the output. The 205 is designed to put out a "full scale" signal. That is, the max Volume setting of the 205 (a Volume of 100 -- or the Output "FIXED" setting, which does the same thing) puts out the Analog audio signal the player is DESIGNED to put out. It's very BEST signal.

Instead, lowering Volume below 100 "attenuates" the full scale output -- lowering the output volume below that of the "best" signal. But how does that affect audio quality? Does it even make a noticeable difference? There are two considerations: Dynamic Range and Noise Floor.

The first takeaway here should be that Dynamic Range is not a problem in the 205. Here's how we get to that result.

The Analog output Volume control in the 205 is implemented at very high quality -- in the 32-bit DACs of the player. That is the Dynamic Range of the Volume control itself is 32-bit. But the max dynamic range of the content you can PLAY in the OPPO is 24-bit. That gives us 8 bits extra.

Each bit of precision is equivalent to 6dB. So that says you could lower Volume by -48dB below full scale and have ZERO effect on the Dynamic Range of the Analog output stage for the content this player can play.

But wait! There's more!

The Noise Floor of the 205 is -120dB below full scale. That is to say any portion of the content which is recorded -120dB, or lower, below full scale is going to be "in the noise".

The maximum potential Dynamic Range of a 24-bit digital audio stream is 144dB. So the lowest 24dB of that will be "masked" by the Noise Floor. What's left gives the maximum perceivable Dynamic Range of the Analog outs: 120dB.

Combining these two results says you could lower Volume a whopping -72dB and still have no effect on the perceived Dynamic Range (i.e., after amplification to a comfortable listening level through a high quality Amp).

----------------------------------------

So what's the problem? The PROBLEM is that -- and this is another key concept -- attenuating the output signal does NOT also lower the Noise Floor! So if you set volume -72dB down (a Volume setting of 28 in the OPPO), you will have lowered the signal you WANT to hear 72dB closer to the Noise Floor. Or to put it another way, you've raised the Noise Floor to -48dB!

When you put that Analog output signal through a high Gain Power Amp to get things back to a comfortable listening level that Noise Floor -- now only -48dB below the loudest portions of the content -- ALSO gets amplified. And may very well become noticeable, particularly in a quiet listening room.

So that raises the question of how high is too high for the Noise Floor? There's no pat answer for that. But as a straw man, let's suggest that for high quality listening you don't want the Noise Floor to be closer than -90dB below the loudest portions of the content.

As I said above, the Noise Floor of the 205 is -120dB below full scale. So that gives us 30dB of Volume control to play with!

In the 205, Volume is implemented as -1.0dB per step below Volume 100. So that says you should TARGET a setup where you can get a comfortable listening level without having to lower Volume in the 205 below Volume 70. Higher is better, but 70 is fine.

If you decide you prefer to be more or less conservative regarding this Noise Floor straw man, you can do the easy math to adjust that TARGET Volume to taste.

------------------------------------------

So what if the Gain in *YOUR* Power Amp is so high that Volume 70 in the OPPO wakes the neighbors and knocks plaster off the walls? Well that says that your Power Amp is not, by itself, a good "match" for the *DIRECT* output of the 205.

One solution, of course is to put a pre-amp between the OPPO and your Power Amp. The pre-amp provides Volume control and so you can leave the Analog output Volume of the OPPO at 100.

Another solution is to invest in some high quality "attenuators" which you will put, in-line, between the OPPO and the Power Amp, so that you can keep Volume in the OPPO at 70 or above (assuming our straw man example here) while achieving a comfortable listening level.

-------------------------------------------

Now does that meant the signal is going to turn to crap if you lower Volume below 70? Of course not. You may very well want to use lower Volumes when you are not doing "critical listening" for example -- perhaps late at night depending on the persnicketiness of the neighbors. In most such cases you will probably NOT notice a decrease in audio quality.

But if you TARGET a setup where you are commonly using, say, Volume 30 for critical listening then you are not using the hardware of the 205 to best advantage.

===================================

ETA: Things Change!

The Official 0922 firmware for the 205, released September 25, 2017 in the US, changed the way the Volume control works.

Rather than -1.0dB attenuation per step below Volume 100, as described above, it is now refined to -0.5dB attenuation per step.


See this post:


https://www.avsforum.com/forum/149-bl...l#post54896420

Thus to achieve -30dB attenuation (the straw man suggested in the math above), you would set Volume to 40, instead of the Volume 70 used in the math above.

That says that starting with this firmware, you can achieve the same level of safety margin regarding Noise Floor if you target a comfortable listening level of Volume 40 or higher -- instead of Volume 70 or higher as described above.

Edited by 08Boss302
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I think its a great chance to try something at a reletively low cost that may get the outcome needed.

 

I dont have the pre/power option so I think if i go down this path i'll grab the source end set i posted the link to above, they'll connect to the rear of the Oppo outputs and then i'll just run the RCA as normal into the back of the amp. 

The -10db will be adjusted at the source (oppo) using these as opposed to the -10db adjustment being made at the connection to the amp.  I doubt using any specific end of the line (output from oppo /input from amp) will make any difference to the outcome or sound but from a space point of view in my set up the oppo has more room out the back than the amp.

 

I'll wait for your update, i agree, reviews are solid and the theory is spot on.

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Oppo's digital attenuator will affect the signal considerably less than Rothwell attenuators, which are just a pair of resistors that form a voltage divider. That by definition will change the output impedance of the player.

 

The only thing that is better (in some ways) than a digital volume control is what Audio GD uses in their preamps (originally patented by Krell) - an output stage gain control rather than a signal attenuator. Also, George will tell you how his lightspeed attenuator is way better than anything else, which is somewhat true, but the implementation is not the easiest one. 

 

I always like to have an additional gain stage after the source.     

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Magic? ??

 

I mean - there is some trapped air as well and solder. Whatever else is there in addition to resistors, it will just make things worst. You do not want to put anything at that point of the signal path. 

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Here is a bit of reading about attenuators. https://www.electronics-tutorials.ws/attenuators/l-pad-attenuator.html

 

regarding buffers - there is a reason why you should use them and that is only if you have an impedance mismatch between the source and load. Using tube buffers in addition to achieving the impedance matting injects a spurious amount of distortion into the signal. If that  is you personal preference - sure - knock yourself out. I would just argue that what you are calling "a sonical improvement" is just your brain registering a difference. You do not have any quantifiable way of showing that the difference is actually an improvement, beyond your subjective opinion, of course. Buffers are a (un)necessary evil in my opinion. You might as well use an analogue equalizer and add a bit of hiss and crackling to your sonical soup.  

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I fully agree - the world is subjective. It only exists from the perspective of an observer. Music included. There is no wrong or right experience. There is, on the other hand, physics/mathematics that supports the reality of this universe and that fact cannot be changed by your personal belief or experience of that universe. 

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I fully agree with what you said. Maybe my ending was not clear in the previous post. Simply because of our subjective experience of the universe and the fact that we fully do not understand the physics of it, we cannot (by definition) experience or measure universe objectively in any way. No matter how hard we try - in fact, the harder we try the farther away we are  from the goal. Is the Schrodinger's cat alive or dead?  The shortcoming of the human condition is that we tend to turn towards a belief when we lack the understanding - we deeply fear the unknown, so we create mythology to escape that fear. The whole of our perception of this universe as an ocean of duality forces around us is the background picture for our myth and legends to describe this world and us in it. Better-worst duality is just one of many that we use. In reality - the better or worst do not exist - there is only us and the experience, nothing else. In a more profound level of experience, us disappears - we become one with the experience and the universe. That is the reason why we listen to music - we chase that selfless expression of reality.  

 

But now we digress from your  problem. 

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On 27/04/2019 at 7:50 AM, Wiredin said:

 

Can't agree with that. I use a couple of valve buffers....one positioned between the pre and power sections of my integrated amp and one between my Oppo 105 player and the integrated amp. With both of these devices are in the 'signal path' and the improvement (sonically) is quite obvious.

Just a question / something to try:

if you take these buffers away from the signal path, do you still have the issue with the Oppo signal being too strong?

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I would suggest that applying digital attenuation to a 16bit data stream is a bad idea, and probably the worst way to go about it. There simply isn't enough resolution in 16bits to allow for this, without introducing significant changes to the resulting signal. Staying "bit perfect" is a good idea, especially with 16 bits, when you consider that the least significant bit, which will get rounded up of off during any mathematical operation that results in an attenuated signal, is indeed insignificant at max level (it carries only 0.0015% of the amplitude value in 0dB samples), but carries 1.5% of the signal amplitude in -60dB samples. If you mess with that you will lose resolution at low level signals. Also, consider that digitally attenuating by -20dB reduces the mantissa length from 16 bits to 13 bits. You're throwing away 3 bits of resolution and you're never gonna get them back.

 

If you're dealing with 24bit data then things look a lot nicer, which IMO is one of the primary benefits of hi-res digital audio.

 

 

 

 

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Yes, I reckon that using a simple voltage divider made from matched, low-noise resistors will be sonically transparent, compared to applying digital attenuation.

 

The resistors will need to be chosen sensibly, so the load impedance for the source isn't lowered too much, and the source impedance for the amp doesn't go too high. Neither of them are overly critical, since sources are usually quite low impedance, and the input impedance of amps is usually quite high.

 

There is no impedance matching at audio frequencies between sources and amps BTW (referring to an earlier post in this thread), the impedances are always very different.

 

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I know that's what I'm doing. The software I use for digital playback (Audirvana) and my streamer clamp the digital volume at max all the way through, volume control is only possible at the amp, using the analog volume pot. I don't have an overload situation to contend with, thankfully.

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@Wiredin

Here are the specs from the Oppo website and the Nad website. It looks to me that the Oppo and NAD are perfectly compatible. I can only surmise your preference for a tube buffer is because of the "sound" it applies to the signal.

I would suggest you will get the lowest distortion by running the Oppo output at 100% straight into the NAD line input.

Using the digital volume control on on the Oppo or adding a tube buffer can only increase the level of distortion.

 

1297177871_ScreenShot2019-04-29at7_27_27am.png.4d82dee96f3574de9d1d845e2583c535.png888841941_ScreenShot2019-04-29at7_26_40am.png.280c0c7becd0a747f5a3a57ede8ba10e.png

 

 

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1 hour ago, Wiredin said:

 

Understand....thanks for the advice, Steffen. Cheers.

Mind you, digital vs analog attenuation is still small fry in the bigger scheme of things. I was just making this argument to counter the notion of digital attenuation being harmless to the signal – it's anything but.

 

However, before polishing asymptotes one needs to get the fundamentals right. For example, I wouldn't worry about digital vs analog volume control before putting some effort into room treatment and speaker placement.

 

In your particular case I would question why this attenuation is required in the first place. A stock standard player should not overdrive a stock standard amp. It seems to me that something is out of spec. Perhaps the tube buffer produces more that 1dB of gain? Perhaps the player or amp need to be checked? This might be worthwhile investigating.

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2 hours ago, Wiredin said:

Just to be clear on this, I'm using the analogue out (RCAs) on the Oppo 105 player, so when the signal leaves the player, it is already in the analogue domain. I'm told that it's best not to attenuate the signal coming from the Oppo (using the Oppo's volume control) because this can degrade fine detail. Not sure about that.

this was basically what my long cut and paste was about.  There is plenty of dynamic range and headroom in the Oppo which is why they stated there was plenty of flexibility in their volume control that would not affect the sound - certainly down to 80 or even 75 was no issue at all - according to their spec etc.

 

I am still keen to read your findings once the Rothwells are installed.

 

I put mine back to 100 and have found (embarrassingly) that my issue was simply me not liking the extra volume the digital side of my set up brings when compared to vinyl.  The volume dial needs not near as much a turn but the sound is actually not an issue, sure there is a little more brightness/harshness, but flicking between hdmi, the analog rca and also use the DAC I have now settled and left it at 100 with the slow phase linear setting on the filter choice. 

I let the player spin a disc for quite a few hours last week on repeat and am now pleased with the sound.  At neighbour annoying volume room acoustics play more a part in my thinking it was overly harsh - not the Oppo's fault.

 

still tho, the Rothwells may serve a a nice simple line level option for me which is also an option but only for that reason, not due to mismatch but more for my own liking to know where the volume dial sits with each application

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Interesting!

I agree that some equipment seems to suit a certain musical style more than another. 

 

Setting aside the personal preferences of vocals etc have the Rothwells corrected the clipping/mis match do you think? 

 

 

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I tried inline attenuators  about 10 years ago and they didn't last, I still have them in the discard box. They may improve some things but you are adding another connection and when removed its sounds better. 

With regards to the 205 its best run direct as pre/dac with volume above 70 for best sound. The only issue I've had is on some older DVD's like Fleetwood Mac The Dance does not have enough output to run volume louder than 100. Never had a problem with blue ray live concerts. Its time this Dvd was upgraded to Blueray with better sound output anyway.

If you are running into a preamp then read this by Bob AVsforum site(Pg10 Official OPPO UDP-205 UHD Blu-ray Player Owner's Thread) in fact this forum posts about Oppo 205 and has everything, worth reading the lot sometime.

Personally if you run a preamp I'd suggest what Bob says below is the best approach. I find the 205 volume control run between 70 and 100 has no influence on the sound quality. Do not add anything in the line between 205 and preamp. Mind you removing the preamp has a bigger effect on the sound, running direct to power amps. I've been running this way for 15 years and can't go back.

Try it sometime make sure you have set volume to variable and reduced it to 20 to start with. Launching this at 100 is very unnerving to ones body I know I've done it fortunately nothing broke except my heart. Robert

 

Quote

As mentioned in my post above regarding direct connection to a Power Amplifier, the "normal" way to wire Analog out of the OPPO is to connect to the inputs of a pre-amp -- which also includes the Analog inputs of an AVR since they always have a pre-amp in those.

When doing so, the USUAL Volume setting for the OPPO is the maximum value of 100 -- or setting Output Volume to FIXED, which does the same thing.

However, depending on the headroom designed into the inputs of your pre-amp, a Volume 100 output signal may possibly "clip" the inputs of the pre-amp in the loudest audio passages you play. The symptom would be a sense of "harshness" in the loudest audio passages, which cleans right up if you lower the OPPO's Volume a bit.

If you hear that, what you should do is test a selection of your loudest audio content and lower Volume on the OPPO just enough to insure you don't have clipping. It will usually only take a few steps reduction of Volume: -1dB to -3dB, meaning Volume 99 to 97. If you DON'T hear clipping in your loudest audio passages, that simply means your pre-amp has enough headroom designed in to prevent it, and you can leave Volume in the OPPO at 100.

Once you have found the Volume setting in the OPPO which insures against clipping of your loudest audio passages that is a "set and forget" setting. I.e., use that same Volume for everything you play. (Of course while using the Volume control in your pre-amp to achieve a comfortable listening level.)

NOTE 1: If you hear "harshness" which does *NOT* go away when you lower output Volume in the OPPO just a few steps, then that's some other problem. For example you may be overdriving your speakers or you may even have a damaged speaker.

 

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The oppo 105 and 205 consist of the ESS dac chips.

 

Here is something interesting what everyone knows.... but as you get into what the DAC chip is capable of in numbers 32bit etc   Look what happens to the presentation on what’s presented when you go from 16 to 32 bit control.  

 

What is also interesting this is all theory that’s proven by measurements. However there is one major difference.   The video doesn’t take into account of wear in the contact point of the resistive wiper on the analog control which is a major factor in degradation.   However digital control have no wear and tear, so take that with a grain of salt.

 

 

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Think you have it wrong!!! Why use wall switch? Its not the attenuators and you are going down the wrong road. Attenuators only reduce signal(resistance) to next component. Remove them and see if that changes things.

I keep my amps on all the time to save warmup. Never ever had a thump. I have 1200 watt x 2 sub amps  and 100 watt per speaker amps on mains thats 400 watts each speaker left and 400 right. Anyway keep playing.

Edited by Robocop
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  • 1 year later...

Hi Team,

 

Doing some searching here on the forum about using my Oppo 205 as a CD source and pre amp for my amps / electrostatic speaks.

 

I’m basically a noob at this stuff and didn’t under stand everything in this thread.

 

Can I use my Oppo 205 as a pre amp? Using the volume control / line level out?

 

Can the out our level be varied? 

 

Cheers.

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Guest DrSK

Yes. I've run a power amp directly from it and will again soon for multichannel HT rears and centre channel. It is better than most AV processors. It is sad how many people plug the 205 into an inferior AVR via HDMI. 

 

You need to check what input voltage your amp can accept. Oppo 205 puts out a maximum of 2VRMS from the RCA at maximum volume. 

 

To use the volume control you will need to configure the 205 so volume output is variable. You can also set the max to less than 100% if 2V is too high and set the start up volume. Note 50% won't be 1V as our hearing and volume controls don't work like that. 

 

To be safe, once volume is set to variable, set volume to 0, when first connecting, and slowly increase. 

 

Edit: As per a subsequent post. Check your amps input impedance is an OK match for the task. Mine was.

 

 

Edited by DrSK
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A word of caution when considering using your oppo 205 as a pre amp

 

ill post some comments from Bob at avsforum son the Oppo thread 

 

and as an example the input impedance of a musical fidelity 2 channel amp

 

 

75000ADF-A87D-44F3-A5E7-69065705D48C.png

31A85ACF-AC03-4DDC-813B-FCC0944C1814.png

7238BE40-38DD-4200-AC16-817F33E47CB9.png

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