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[mmg18]

Hello,

I am currently evaluating JRiver. I want to use it for its convolution engine with DLNA. I created filters using DRCDesigner, but when I enable convolution in JRiver DSPStudio, the result is much more quiet than when I disable it. It's at least a 12dB difference, maybe more. Is this normal or is there a problem with my filter?

[mattkhan]

it depends on your filter, i.e. if the target curve is far away from the measurement then that can mean a lot of attenuation is baked in. However jriver also recommends the "normalise filter volume" checkbox which cuts another 6dB off, I'm not sure why it is recommended but it's better (IMO) to normalise gain in your filter instead as you can do it accurately.

[mmg18]

Thanks for your reply. I'll try with normalization off.

Could it be because I recorded the sweep to soft? I remember DRCDesigner saying the sweep was recorded at -15dB.

[Trumpetguy]

My Audiolense filter eats more than 25dB, and as far as I have found, this is quite normal.

[JimH]

There is a long thread on convolution here.  Please try a search.

[mmg18]

I tried searching, both on google and on the forum. I found a lot on convolution, but nothing on volume issues. If you could point me in the right direction I'd be most grateful.

[mattkhan]

Thanks for your reply. I'll try with normalization off.

Could it be because I recorded the sweep to soft? I remember DRCDesigner saying the sweep was recorded at -15dB.

No, the gain lost in the filter is the difference between the target and the measurement. The absolute SPL is irrelevant (excluding any snr concerns). Losing 25dB in a filter does not sound normal to me btw. Mine is typically a few (maybe 5ish?) dB.

[Trumpetguy]

No, the gain lost in the filter is the difference between the target and the measurement. The absolute SPL is irrelevant (excluding any snr concerns). Losing 25dB in a filter does not sound normal to me btw. Mine is typically a few (maybe 5ish?) dB.

You are quite right, it's not 25dB lost. I confused it with the target level in my old setup (pre bass traps), which ended up at -25dB.
My current rig shows on average - left channel in the image - I'd say a 10dB reduction. I have set Audiolense to boost max 9dB, so that figures.

This is more in line with OP's concern. And 10dB is noticeable and even with normalized filter I need to turn the (Internal) volume up to get same level as without convolution. I have never really measured how much.

(BTW this is a 7.1 setup, and the left main has an 40Hz XO to the two subs.)

[mmg18]

it depends on your filter, i.e. if the target curve is far away from the measurement then that can mean a lot of attenuation is baked in. However jriver also recommends the "normalise filter volume" checkbox which cuts another 6dB off, I'm not sure why it is recommended but it's better (IMO) to normalise gain in your filter instead as you can do it accurately.

I tried turning off the filter volume normalization. Can't say it changed much volume-wise, but it did cause distortion in loud tracks. Wouldn't recommend turning it off...

[mattkhan]

I tried turning off the filter volume normalization. Can't say it changed much volume-wise, but it did cause distortion in loud tracks. Wouldn't recommend turning it off...

this implies your filter is regularly above 0dB, I recommend you look at the filter and see what it is doing (and attentuating by just enough instead of a fixed 6dB)

[mmg18]

this implies your filter is regularly above 0dB, I recommend you look at the filter and see what it is doing (and attentuating by just enough instead of a fixed 6dB)

Ok thanks. What is the best way to inspect the filter? I just have a .wav file. I'm using DRCDesigner, which doesn't allow me to visualise the filter.

[mattkhan]

you may be able to import it into REW or HolmImpulse (or other similar measurement software)

[mmg18]

you may be able to import it into REW or HolmImpulse (or other similar measurement software)

Interesting, I didn't know this was possible. I had to convert the filter to 16-bit PCM first, then I was able to import it in REW. In the image below the top graph is my filter and the bottom graph is the measurement itself. Looking at the filter I see 2 possible reasons for the volume issue:
1. Frequencies below 50Hz are boosted by about 15dB. There is no need for this since I don't use a subwoofer and my speakers (CM10) can't play those frequencies.
2. There is a 15dB dip at 20kHz. No idea why it's there.

Does anyone know how I can fix this using DRC or DRCDesigner? DRC has so many parameters I don't know which to change...

[mattkhan]

it looks like you need to set a lower limit to the correction (and an upper limit and also use a shorter window as that correction is pretty spiky). Unfortunately I'm not familiar with DRCDesigner so can't comment on how to do that. There is a fairly active thread on diya on DRC that might be a good place to ask - http://www.diyaudio.com/forums/full-range/275730-convolution-based-alternative-electrical-loudspeaker-correction-networks.html

in the meantime you could add a high pass in a PEQ block after the convolver

[mmg18]

Thanks!