Sub out question

[Schroeder]

I have my Ultra going through my Denon receiver which I use for my HT system. I use the sub out from the Denon into the LFE input on my sub. I read that you can add 2 sources to the sub, receiver to the LFE input, and a stereo source to the L input. But that assumes the sources play independent of each other. The Ultra has the crossover, so I was wondering if I set the crossover, it would send the low frequencies to the sub and not to the Denon. Think there's any harm in trying it, or do I risk damaging the sub?

(cross posted on Steve Hoffman's forums)

 

[jkdjedi]

I have my Ultra going through my Denon receiver which I use for my HT system. I use the sub out from the Denon into the LFE input on my sub. I read that you can add 2 sources to the sub, receiver to the LFE input, and a stereo source to the L input. But that assumes the sources play independent of each other. The Ultra has the crossover, so I was wondering if I set the crossover, it would send the low frequencies to the sub and not to the Denon. Think there's any harm in trying it, or do I risk damaging the sub?

(cross posted on Steve Hoffman's forums)

I don't see how that could harm your sub? That's what it was designed to do in the first place.

 

[spicypadthai]

You will be fine. The LFE is a specific channel, the ".1" in home theater, and it's different from the low-level RCA input used to connect the Ultra to the sub. I used a REL sub for 10 years connected simultaneously to my AVR via high-level connections and LFE.

 

[harkpabst]

You will be fine. The LFE is a specific channel, the ".1" in home theater, and it's different from the low-level RCA input used to connect the Ultra to the sub. I used a REL sub for 10 years connected simultaneously to my AVR via high-level connections and LFE.

That's a different situation, though. The REL's high level inputs are completely isolated from the RCA inputs. The same goes e.g. for BK Electronics subwoofers.

In most cases where there are R + L RCA input and one of them is marked as the LFE input, it doesn't really matter which one you use. They behave just the same. Both inputs, L + R, should usually feed a summing amplifier to create a mono signal in case there are different signals reaching the left and right input. This ensures a degree of decoupling of both inputs, so it's probably OK to use the sub in this way.

@Schroeder, if you happen to own a multimeter you could try and measure the electrical resistance between the middle contact of the L and the R RCA socket. As long as the reading is 2 kOhms or above, it should be safe.

 

[spicypadthai]

That's a different situation, though. The REL's high level inputs are completely isolated from the RCA inputs. The same goes e.g. for BK Electronics subwoofers.

In most cases where there are R + L RCA input and one of them is marked as the LFE input, it doesn't really matter which one you use. They behave just the same. Both inputs, L + R, should usually feed a summing amplifier to create a mono signal in case there are different signals reaching the left and right input. This ensures a degree of decoupling of both inputs, so it's probably OK to use the sub in this way.

@Schroeder, if you happen to own a multimeter you could try and measure the electrical resistance between the middle contact of the L and the R RCA socket. As long as the reading is 2 kOhms or above, it should be safe.

True, I read the OP post as the sub having dedicated/specific LFE and low level inputs, vs. L + R with R also being LFE. If it was my sub, I'd try to confirm the proposed config with the manufacturer.

 

[harkpabst]

If it was my sub, I'd try to confirm the proposed config with the manufacturer.

That's an exceptionally good idea.

So far we don't even know the sub's brand.

 

[sNc]

I have a question that no one answered me earlier in another post, and it is important to me for the sake of peace of mind.

Is changing the output level from 2vrms to 1vrms, equivalent to only decreasing the volume by a specific value? Can maneuvering the output level, by decreasing it, may have any negative effect on the sound?

 

[harkpabst]

I have a question that no one answered me earlier in another post, and it is important to me for the sake of peace of mind.

Is changing the output level from 2vrms to 1vrms, equivalent to only decreasing the volume by a specific value? Can maneuvering the output level, by decreasing it, may have any negative effect on the sound?

The output voltage setting on your WiiM Ultra (if I remember correctly?) is not related to the subwoofer output level. It affects the analogue stereo line output, only.

The best value depends solely on the input sensitivity of the power amp or powered speaker (same thing, as there is still at least one power amp build into a powered speaker) you are using with your Ultra. Generally, you will wanat to be able to reach the maximum output power from the power amp with the WiiM Ultra's volume control at 100%. If full output power requires 2 V input voltage, this is what you will need as the ideal output voltage of the Ultra. If your power amp has a higher sensitivity, a higher gain (so a lower voltage to put out full power) you should reduce the output voltage of the WiiM Ultra to avoid clipping.

This is the most important aspect regarding the output voltage. You need to use the value that matches your equipment best.

A stronger signal is less prone to interferences, so using the highest possible output voltage might appear to be best at a first glance. But in reality it's far more important to understand the gain structure of your devices. Some people get the feeling of their amp being weak just because they have to increase the volume to something above 50%. This is wrong. Chose an output voltage that lets you reach the highest level you'll ever want with the volume control at 100% and you're done. This will result in the best possible sound.

 

[spicypadthai]

If your power amp has a higher sensitivity, a higher gain (so a lower voltage to put out full power) you should reduce the output voltage of the WiiM Ultra to avoid clipping.

This is the most important aspect regarding the output voltage. You need to use the value that matches your equipment best.

+1 to this. My (new) amp has two gain modes: fixed and variable. The sensitivity for fixed is 0.7 and variable is 0.5. I'm using it in fixed and controlling volume via the Ultra, so I have been toggling the output between 800 mVrms and 1 Vrms as I get more familiar with the amp. Having a little headroom for quieter recordings is generally a good idea. If it starts clipping, especially at much lower than max volume, then lower the output.

 

[harkpabst]

+1 to this. My (new) amp has two gain modes: fixed and variable. The sensitivity for fixed is 0.7 and variable is 0.5. I'm using it in fixed and controlling volume via the Ultra, so I have been toggling the output between 800 mVrms and 1 Vrms as I get more familiar with the amp. Having a little headroom for quieter recordings is generally a good idea. If it starts clipping, especially at much lower than max volume, then lower the output.

That would be my approach, exactly.

 

[sNc]

The output voltage setting on your WiiM Ultra (if I remember correctly?) is not related to the subwoofer output level. It affects the analogue stereo line output, only.

Ugh...sorry, I don't know how I missed that this is a topic about subwoofer. Somehow I saw "All things about WiiM Ultra" and tho this is general Wiim Ultra topic.

My Fosi V3 monos have 1.64Vrms with RCA

Thank you for the deeper explanation

 

[harkpabst]

My Fosi V3 monos have 1.64Vrms with RCA

I have mine set to the lower gain setting (25 dB instead of 31 dB) and the Ultra at 2 Volts max. Very satisfied with this setup (but never need the full power anyway).

 

[sNc]

I also have mine set to 25db. Did you ever have to crank the volume to 100% with 1vrms?

 

[harkpabst]

I didn't try 1 Vrms, because 2 V is the default and worked just fine. For background listening the volume usually between 30 and 40 with streaming sources, somewhat higher when just listening on my own.

If your speakers' sensitivity is rather high you might get away with 1 V, otherwise maybe not. With volume levels at 30% or higher the digital volume control should already be perfectly lossless, if this is your concern.

Just give it a try. You cannot break anything.

 

[sNc]

if this is your concern.

Yes. With 2V, I must use 70% limit and around 25% to 70% volume. I was wondering if such a low volume (25% with 70% max limit) is not worse than limiting output to 1V with higher volume

 

[spicypadthai]

Yes. With 2V, I must use 70% limit and around 25% to 70% volume. I was wondering if such a low volume (25%) is not worse than limiting output to 1V with higher volume

It depends on what you mean by "worse". If you are concerned about accidentally increasing the Ultra volume and damaging your speakers, then setting the output to 1 may make sense. But you won't be maximizing your amp which may or may not be a concern. Whether any of it is audible and if yes, whether it is better or worse are different questions. I prefer the output to be at least equal to the input sensitivity so there is some headroom on both sides. Setting the output lower may mean more noise if/when you turn up the volume but again, is it audible and do you care? My two cents: I'd stick with it at 2 unless it is clipping, but test and see what sounds best and best fits your usage.

 

[Cal_Cobra]

I have a Onkyo Dolby Atmos 5.2.4 home theater system and a dedicated stereo system. The home theater system has two sealed 12" active subs chained together. On the last sub, I have a RCA A/B switch box so I can share the same LFE sub input between either system. There are more expensive and robust options out there, but this is what I'm using now and it works fine. I have my subs, and stereo equipment and amplifier(s) connected to a Monster Power HTS5000 Mark II Reference PowerCenter switched line conditioner/surge suppressor, and the subs are turned off when not in use.

 

[jkdjedi]

The output voltage setting on your WiiM Ultra (if I remember correctly?) is not related to the subwoofer output level. It affects the analogue stereo line output, only.

The best value depends solely on the input sensitivity of the power amp or powered speaker (same thing, as there is still at least one power amp build into a powered speaker) you are using with your Ultra. Generally, you will wanat to be able to reach the maximum output power from the power amp with the WiiM Ultra's volume control at 100%. If full output power requires 2 V input voltage, this is what you will need as the ideal output voltage of the Ultra. If your power amp has a higher sensitivity, a higher gain (so a lower voltage to put out full power) you should reduce the output voltage of the WiiM Ultra to avoid clipping.

This is the most important aspect regarding the output voltage. You need to use the value that matches your equipment best.

A stronger signal is less prone to interferences, so using the highest possible output voltage might appear to be best at a first glance. But in reality it's far more important to understand the gain structure of your devices. Some people get the feeling of their amp being weak just because they have to increase the volume to something above 50%. This is wrong. Chose an output voltage that lets you reach the highest level you'll ever want with the volume control at 100% and you're done. This will result in the best possible sound.

I dropped mine to 1 vrms only for the warmer sound I got. And it's super rare I ever get to 50% volume on the amp, it's got some power. I also read it somewhere if there was any hint of distortion then for sure you'd want to drop that to 1 vrms or (lower) until that distortion was gone.