Struggling to get LFE through REW

[justinking58]

Afternoon all,

I'm hoping someone can help as I'm really struggling.

Essentially it seems my problem is I am not getting the right bass measurements when using REW. I'll post some graphs below which might explain, I though the trend would be much more flat rather than the steep upwards curve?

Is there a high pass filter being applied somewhere?

My equipment is, Dell Windows laptop, umik 1, Denon 3700 AVR, SVS Pb2000 Pro sub. Connected via HDMI. Using Java as I cant install Flexasio

Apologies for the dump of screen grabs, but hopefully they might show my problem better than me typing..

If I use the generator I am able to just play a 25hz tone and hear it from the sub. And all other sources such as YouTube and test tones also use the sub. Which is pointing me towards something within REW?

Thanks for any assistance

 

[John Mulcahy]

With Java drivers on Windows you can only send signals to left and right, your AV processor is applying the bass management filter in your left/right speaker setup. It is not redirecting to the sub, which is probably due to the surround mode you have selected.

 

[justinking58]

Hi John,

Thanks for the quick reply. I'm not sure I completely understand though.

Are you saying that with my set up I won't manage to get the sub sweep done? I assumed L/R/L&R would have included the sub?

I have tried various sound modes on the AVR but I might have missed the correct one

 

[John Mulcahy]

Whether content is redirected to the sub depends on the processor surround mode, REW has no influence on it.

 

[justinking58]

OK thanks.

I can definitely hear the sub, and can get it working on its own using the Generator at a low frequency.

When I check levels using the subwoofer though, I think most of the sound is coming from the L&R

Unless I'm misunderstanding, my laptop / java set up just won't work?

 

[John Mulcahy]

The set up should be fine, there is nothing wrong with using the Java drivers. Focus on the processor mode. If none of the processor modes redirect to the sub (which seems unlikely if you say you hear signals from it) you could use an analog connection from the laptop's headphone output.

 

[justinking58]

Ok bit of an update this morning, I have disconnected the mains and running the sweeps. All sound coming from the subwoofer. I'm still getting very little at low frequencies?

This is with a Bass sweep playing from youtube and RTA running..

 

[JStewart]

Have you checked that windows sound enhancements are off for the mic?

 

[justinking58]

No but that's an excellent suggestion. I'll check.

Interesting I did hook up my old sx120 subwoofer and got very similar results which is very odd..

 

[justinking58]

 

[justinking58]

Have you checked that windows sound enhancements are off for the mic?

View attachment 44366

That was exactly the issue! Thank you

 

[John Mulcahy]

There seems to be a growing trend for laptops and PCs to apply noise cancellation processing to stereo microphone inputs, suppressing the content that is common to both channels. With a UMIK the signal is the same on both channels, so it is all common content. A report earlier this week (thank you, Ken!) on an ASUS laptop showed levels down by almost 90 dB across the range until the "AI noise-cancelling microphone" feature was turned off for the UMIK input.