Wiim Ultra output voltage

[Malte74]

Hi everyone!
I have a Wiim ultra with a couple of power amplifiers connected to it (one for the front and one for driving two large passive subwoofers). I have no issue with the output input matching, no hiss on idle and no distorsion from overdriving amplifier inputs but I'm curious which, in theory, should be the best output voltage between 1V or 2V.. I understand that lowering output to 1V cost some SNR but since I do most of my listening with the volume between 30-50 (50 is loud..) with 2V and 1V lets me use much more of the volume (50-75/80) I guess I can take some of the lost SNR back in that end?
Is there an argument for one being better than the other? When listening and comparing 2V might, just might, be a touch meatier and more dynamic while 1V might, just might, win on clarity and soundstage but since I have to adjust volume to what is close enough between the two everytime I switch is not exactly A/B so it's hard to tell. I know I should listen and choose what I prefer and that is what I'm doing (2V just because it changes volume quicker when using the tv remote in hmdi-mode) but I'm here to learn and I repeat the question: Is there some technical reason to why one of the options would be better, even If inaudibly so, than the other?
Regards/Martin

 

[hipoagumol]

As long as your amplifiers are ready to receive 2v input signals (if they are modern, they do, if they are vintage then maybe not) then 2V is the correct choice of out voltage for Ultra as it maximizes SNR earlier in the audio chain.
Copilot put in more technical wording:

At the output of the Ultra's DAC:

• 2 V gives you ~6 dB better signal‑to‑noise ratio than 1 V
• This is because the analog noise floor stays the same, but the signal is larger

This is why higher line levels became standard in hi‑fi over time (CD players settled on ~2 Vrms).

2 V reduces downstream gain requirements
With 2 V:

• Your power amps need less gain to reach the same loudness
• Less gain means less amplification of their own input noise and distortion

This is especially relevant with:

• Multiple power amps
• Long interconnects
• High‑sensitivity speakers or subs

So on paper, 2 V wins.

 

[Valentino]

What is the sensitivity of your amps? Check specs.
I always recommend setting the Ultra output voltage equal to or below the amp’s specified sensitivity. Thus the amp cannot clip, even with the ultra volume at 100%.
Worth noting that above 50% 1% change equals appx. 0.3 dB, so at 50% you’re at -15 dBFS.

 

[mlsstl]

The way I do.it is to use the output voltage that gives my loudest desired listening level at about 75% to 80% max volume. That leaves a bit more still available for softly recorded material and also leaves plenty of volume control range when I'm not listening at my max loudness. (I find it annoying when I hit my loudest desired level at 30% or 40%)

 

[Malte74]

The amps are apart audio champ 2. Specs say that on rca input it's 10Kohm 1V 0dbfs. They have weird gain controls. Even at 1V I can have them set to minimum and still get enough volume. The difference between minimum and maximum are pretty small. More importantly I hear no strange thing on 2V and gain on maximum. No hiss, nothing that resembles input overload-related distorsion.. It just works.
This is my usual problem and the reason I posten the question (it's been floating around some swedish forums for a while now..): One says this, someone else something else..
What is more important for sound quality? Being able to use more of the volume control or the 6dB loss in SNR? SNR is pretty good on a Wiim Ultra so are those 6dB:s even audible?
A bit strange that with the wiim set on 2V and the gain controls on the amp on full I get no deteriation in sound quality (I'm a relatively experienced listener).. It should distort like crazy but it just works, and works fine..

 

[Deleted member 29222]

...
A bit strange that with the wiim set on 2V and the gain controls on the amp on full I get no deteriation in sound quality (I'm a relatively experienced listener).. It should distort like crazy but it just works, and works fine..

This has been my experience as well.
As a side note, I noticed that when I decrease the output voltage of the Wim ultra, my subwoofer becomes more prominent in the mix. It acts almost like a loudness?

 

[hipoagumol]

According to specs this amp has input sensitivity 0.775v or 1v, I find diverse dara. So it is initially designed to give its maximum gain for that input level, hence you should feed it with signal <=0.775v)/1v
Reason you can't hear any clipping or distorsion is because that amp also has advanced protection circuitry (APC) that prevents clipping it by dynamically adjusting gain and reducing signal input peaks. More detail here
However the best signal quality you can get of it and also volume range at the output is to make it work as designed.
So my advise is then to adjust the wiim ultra output voltage to 0.8v-1v


Regards

 

[hipoagumol]

By the way I found the manual and there's a Led that lights when this APC feature is working. So In theory with ultra output set to 2v you would see it ON very often while with proper input voltage it should stay all the time OFF, meaning the protection is not acting on the input signal to adapt it, which is the ideal situation.

https://pa-systems.ru/media/catalog/item/1000/580/CHAMP-2.pdf

 

[Malte74]

Running 1V now.. Sounds equally good but normal listening now is in the 60/70-range instead of 40 something.
Are those 6dB:s of SNR something to worry about? One initial plan was to use 2V and compensate by having the gain controls low..but they make such a small difference.
I agree on the subwoofer out, I have to cut output by 2 to 3dB when using 1V but maybe the subwoofer out is unaffected by the voltage-setting?
"hipuagumol"
I have never once seen the apc led come on.. I've played yello and infected mushroom with the gain on full, volume 70 plus and 2V output and things were moving around in my 45m2 livingroom.. Just the green led.

 

[Valentino]

IIRC the Ultra’s noise level lies at something like -115 dB at 2 V, so no, you will not hear those 6 dB.

 

[rjp]

This has been my experience as well.
As a side note, I noticed that when I decrease the output voltage of the Wim ultra, my subwoofer becomes more prominent in the mix. It acts almost like a loudness?

That's because the adjustable output voltage only effects the line out, not the sub out.
So if you decrease your line out from 2v to 1v, you need to decrease your sub volume by 6dB to match.

 

[harkpabst]

That's because the adjustable output voltage only effects the line out, not the sub out.
So if you decrease your line out from 2v to 1v, you need to decrease your sub volume by 6dB to match.

Yes, and this is exactly how it should be. Selectable output voltages are available to match different input sensitivities of different power amplifiers.

In any case, the balance between mains and sub must be set up once and whenever somebody decides to change the output voltage for other reasons.

 

[cristoo]

Hi

If may jump in taking opportunity of this topic coz I am a bit lost how set up my amp properly with wiim ultra in terms of sensitivity.

I have smsl da-9 amp, according tech spec it has 250 mV/47 Ohm sensitivity.

I use Wiim’s volume control and keep smsl at fixed seething - at the moment approx 30 out of 70. I did some testing and 35 I also fine. The additional problem of mine is hiss in amp on volumes above 40 when use rca connection. It is only when connected wiim is powered, when power plug is out, the hiss is gone, also is not present on xlrs (but nothing is connected at the moment). But this is side problem.

Now at first when I was unaware of sensitivity issue I used 2v line out setting (standard/max) and with amp 35 volume setting I had to set volume on ultra in range 20-30 to have really loud playback. And I thought it was fine.

Than I read that I should match line out setting to amps sensitivity so I change it to minimum which is 200 mV. I reduced amp volume a bit to 30-32 and now I have to use ultras 90-100 volume scale to have proper volume but still is bit too low for headroom. I don’t want crank up amp to much because of this hiss but 35-38 on amp is still fine so it might be a solution.

I use also sub and don’t change its seeting (gain), but re-run RoomFit each time in play with above settings.

To sum it up : what seetings shoul i use for ultra line out to get best results and sound quality with my amp.


Best regards,

Kris

 

[hipoagumol]

The hiss is because your signal is so low at the input that is almost comparable to the noise, so when turning up the volume you can actually listen the noise that is mixed with your source signal . In other words you are working with very low SNR becuse of too low signal output from Ultra. Modern amplifiers like yours (actually all amps post CD era) are designed to work with 2V signal inputs.That's the standard, why would all modern sources (cd players, tuners, streamers) would produce 2V outputs if all modern amplifiers (which have 200-250mV sensitivity as yours) would saturate with it? Only 60s-70s amps you need to worry about of saturating amp with too "hot" inputs. And you'll hear it.
Actually to maximize SNR the higher the signal the earlier in the sound chain the better.
We should not to mix up input sensitivity with input overload. Input sensitivity is the minimum voltage for which your amp is still able to provide its nominal max power with the volume knob all way to max.
The only 'con' of feeding amp with 2V signal is that your amp knob would probably end up maybe between 9-10 o clock fot your normal listening levels. That is also no issue at all if your idea is to fix the amp level and control volume with the source (wiim) . If you aimed to control your volume with the amp then the problem would be it would be a bit 'too nervous' volume response and dificult for you to control actual sound pressure levels: little rotation would mean quite large volume changes. But since you will be using ultra's volume steps there is no issue on having your amp volume fixed to 30%-35%.
Some may claim that amp volume knob on its lower end may have channel imbalance issues and others, but again that will not be the case either with modern amps like yours as attenuation is not controled with carbon track potentionemer (that may cause those imbalance issues at low volumes) but with electronic chips. Actually your SMSL DA-9 uses chip NJW1194. This is a digitally controlled atenuator that would work with same precision in all volume range 0 to 100% (although you have a physical knob that will not act on the sound path directly as vintage potentiometers, will just tell the atenuator chip what attenuation to apply with its very precise electronics).

Then there is the possible issue with digital clipping on ultra (which is not depending on the output voltage).
There is no clear consensus/info on how wiim handles the sucesive gain stages (pre gain per input, roomfit if allowing boosts, peq/visual eq and final DAC potential ISP).
To be on the safe side the general advise of the community is to use volume limit setting in your ultra so as it compensates the maximum gain introduced by the sum roomfit and post equalization if you use them plus 2-3 dB. Volume limit in Ultra adds-3dB attenuation for each -5%.
To simplify my advise is use roomfit always in non boost mode and then check if you are using EQ or PEQ what is the maximum positive Gains filters/band you are adding. For example if you use the presets like Classical, Rock, Electronic, those usually won't go above 6-7dB positive boost on some freq bands. So you will be safe of digital clipping and ISP by setting volume limit 85% (-9dB).

 

[harkpabst]

No, I don't think that the hissing problem can be explained by the maximum output voltage of the WiiM Ultra set to 200 mVrms.

The actual output voltage with the volume control set to 90 and 0.2 V is almost identical to the actual.output voltage with volume control set to 30 and 2 V.

I agree that the hissing is the real issue to solve here, though.

 

[HansD-NL]

No, I don't think that the hissing problem can be explained by the maximum output voltage of the WiiM Ultra set to 200 mVrms.

The actual output voltage with the volume control set to 90 and 0.2 V is almost identical to the actual.output voltage with volume control set to 30 and 2 V.

I agree that the hissing is the real issue to solve here, though.

Yes also agree, that's the nut to crack. Where is it coming from. But I must say that hipoagumol messages are full of very useful en truthful info.

 

[cristoo]

I don’t really know where this hiss is coming from, on levels higher than 40/45 out of 70 is turns into cranks, so I try to avoid volume higher than 35/38 coz in that situation hiss is not audioable. But it had to be said that I do all eveluations it this problem with head by speaker, not in my listening position. By that i mean that this initial hiss is very subtle and one has te close to speaker to hear it but it is present.

Amp has only rca and xlr inputs, no digital. I tried to switch to balance input (nothing connected) - silence. Tried to check unbalanced input with ultra with power cord unplugged - silence. Ultra powered with on and standby mode - hiss.

To be added - I have really huge mess in terms of cable management so power cord for audio, tv, and different media boxes are mixed with speakers, hdmi and interconnect cables. At the moment I can’t do much about it unless i rearrange my room a bit.

I use ultra stock rca cables if it matters.

 

[hipoagumol]

No, I don't think that the hissing problem can be explained by the maximum output voltage of the WiiM Ultra set to 200 mVrms.

The actual output voltage with the volume control set to 90 and 0.2 V is almost identical to the actual.output voltage with volume control set to 30 and 2 V.

I agree that the hissing is the real issue to solve here, though.

It is explained! I think he is talking all the time of amplifier's volume, not Wiim's! Wiim's output SNR, and further chain SNR including cables, input stage of amp etc is maximized by using 2V and there is no analog clipping risk at the SMSL because it supports signal even higher than 2V without overload.
Every analog component—the Wiim’s output stage, the RCA cables, and the amplifier's input stage—has a baseline of electrical hiss and thermal noise. This noise floor is constant; it is always there, and its volume does not change based on the strength of the music signal you send through it. If you send a signal of max 2V instead of max 200mV, you are maximizing the gap between your music signal and that background noise (Maximize SNR)
@cristoo
When you turn up the SMSL volume beyond to compensate for the weak 200mV provided input, it amplifies the music, but it also amplifies the background noise of the RCA cables and the WiiM's output stage which is much similar to musical signal's amplitude if using 200mV output than using 2V and that's why you can hear it. The noise floor is much closer to your desired signal when using 200mV and I am pretty sure that is the reason you hear hiss. Beside that , according to later comments about cable mess there may may be also some inducted noise problem that worsen things .

Think of a recording yourself talking in a basket stadium. You playback that recording later at home and you hear a lot of noise of other people. Regardless if you play it louder you won't hear your voice clearer, the other people's voices are also amplified (SNR is poor) and the lauder you play you will hear your voice louder but you will also hear the other conversations that were happening around you clearly. The only way you can enhance your recording is if you talked much lauder when recording (stronger signal over noise). Then for the same playback level as previous test you would hear your voice much clearer and the other conversations won't disturb so much.
Your ultra controling volume + amp at fixed volume will work better with ultra's 2V outputt. If you don't believe read the dataset of the volume control chip it uses, this was given by Gemini:
"New Japan Radio explicitly benchmarks and specs the NJW1194 chip’s optimal performance metrics (such as its lowest Total Harmonic Distortion of 0.0015%) using an input signal of exactly 2Vrms.
Furthermore, the chip's maximum output voltage threshold before it clips is rated at 3.6Vrms minimum (typically closer to 4.2Vrms). "

 

[cristoo]

The hiss is audiable even when wiim is in standby so without music playing. I just have to turn up amp volume above
38/40 and I can hear. Above 45 there are cranks.

What I did: raised line out voltage - no change. Swapped different rca cables - no change. It is not new problem, I guess it was like from beginning i just got used to it but I don’t think it is normal. What I can do also is to connect spare smsl su-1 as external dac and check the hiss.

 

[hipoagumol]

@cristoo my advise test:
- set smsl amp volume to 0
- go back to 2V output on wiim ultra
- set ultra's volume limit to 85% (to have some headroom for eq and ISP)
- set ultra playback volume to 100% with wiim home app , remote or whatever
- play highly dynamic music
- Start turning up smsl's volume up to the maximum level your ears will ever like to cope with
- lower ultra's volume back to normal listening levels
Now you have it. Stick the smsl volume to that level forever ans just use ultra's volume controls .
You've been confused about sensitivity meaning.
Some Gemini explanations, English is not my mother tongue so the IA may convince you more than I do:
"A common source of confusion with modern amplifiers like the SMSL DA-9 is the published specification: Input Sensitivity: 250mV.
Many people mistake this for an overload limit, assuming that anything over 250mV will cause analog clipping. This is incorrect.
What Input Sensitivity actually means: It is the amount of voltage required to drive the amplifier to its maximum rated power output when the amplifier's internal volume knob is turned up to 100%.
The Reality: If you feed it a weak 200mV signal, you have to crank the SMSL’s volume high, which amplifies the baseline noise of the chip and the cables. If you feed it 2Vrms, you have a 20dB cleaner signal-to-noise ratio entering the amp, meaning the SMSL's internal volume doesn't have to work nearly as hard to achieve the same room volume."