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Would a passive volume controller degrade signal?

moniker42

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Nov 25, 2024
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I am using a WiiM Pro Plus to drive stereo speakers. It's nice but I would like to be able to control the volume using the Apple TV Remote. Of course the WiiM doesn't have an IR receiver, so I am thinking about buying a Omnitronic LH-125 IR Volume Controller and pairing the Apple TV Remote to that.

Having forked out for the extra-caramelised DAC and some acoustic treatment I wouldn't want to muddy the signal at the final stage… but what could go wrong with a passive volume controller? Does anyone know? Any advice appreciated.
 
A resistive passive controller has zero distortion and minimal noise, so is the most transparent 'preamp' possible. However, there are some caveats:- They have a variable output impedance that is well higher than an active preamp, so that limits the cable length from the preamp to the destination. In practice, with decent low capacitance cable, 5-7 metres is no problem, so may not be an issue. Secondly, they tend to be 10k or 20k input impedance, so lower than many active inputs, but again well within the driving capability of most modern sources, although may not be great with vintage valves.

In your case, I can't imagine any issues whatsoever.

S
 
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That's great, thanks. Cable is only 3m on both sides.
 
I am using a WiiM Pro Plus to drive stereo speakers. It's nice but I would like to be able to control the volume using the Apple TV Remote. Of course the WiiM doesn't have an IR receiver, so I am thinking about buying a Omnitronic LH-125 IR Volume Controller and pairing the Apple TV Remote to that.

Having forked out for the extra-caramelised DAC and some acoustic treatment I wouldn't want to muddy the signal at the final stage… but what could go wrong with a passive volume controller? Does anyone know? Any advice appreciated.

That RCA volume unit is exactly what I'm looking for but I can't seem to find it anywhere available for purchase from the states...:(
 
A resistive passive controller has zero distortion and minimal noise, so is the most transparent 'preamp' possible. However, there are some caveats:- They have a variable output impedance that is well higher than an active preamp, so that limits the cable length from the preamp to the destination. In practice, with decent low capacitance cable, 5-7 metres is no problem, so may not be an issue. Secondly, they tend to be 10k or 20k input impedance, so lower than many active inputs, but again well within the driving capability of most modern sources, although may not be great with vintage valves.

In your case, I can't imagine any issues whatsoever.

S
Would you say this goes for a passive, unpowered RCA knob as well? Such as this one: RCA Knob ? I would like to have one of these going from the sub out of my Bluesound ICON to my subwoofer amplifier. The sub amp is tucked away and I like to have control over the bass at my finger tips. The bluesound does not let you control sub out volume, only crossover frequencies.
 
IMG_9386.jpeg
 
Sorry about that. The link took me to a non u.s. site. So I went there and linked without looking. My Bad!!
 
Would you say this goes for a passive, unpowered RCA knob as well? Such as this one: RCA Knob ? I would like to have one of these going from the sub out of my Bluesound ICON to my subwoofer amplifier. The sub amp is tucked away and I like to have control over the bass at my finger tips. The bluesound does not let you control sub out volume, only crossover frequencies.
That's exactly a knob in a box, a perfect volume control subject to the limitations I mentioned above. As long cable lengths only affect higher frequencies, for a sub you could use almost any length of cable. Low capacitance, well screened cable like RG59 or RG6 will be fine, although they might be a bit stiff.

S
 
That's exactly a knob in a box, a perfect volume control subject to the limitations I mentioned above. As long cable lengths only affect higher frequencies, for a sub you could use almost any length of cable. Low capacitance, well screened cable like RG59 or RG6 will be fine, although they might be a bit stiff.

S
I’m not familiar with those cables you mentioned. Can you provide a link?

Also, what do you think of these? It’s a powered rca volume control with a remote.

I’d like to get the rca version but they ask which impedance and I have idea no clue which one to use. My best guess would be 50k because typically the passive rca units I mentioned above use a 50k potentiometer.
 


JSmith
 
Hello again, I still haven't hit the button on an Omnitronic LH-125 as I've been busy faffing with projector and speaker placements. It's also out of stock, but local sites say they'll have it in a few weeks.

Now thinking that it would be nicer to buy a Topping E50 so that there is a screen showing the volume, but $200 USD for volume control! RIP the budget
 
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