Gain loss from filter generation

peelbone

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Hi all!

Here is a new question for the forum.
ive made a filter based on the standard time allignment filter with only change to the max correction boost from 6db to 10 db.
This is the result:
56524


Should i lower the output on my subs prior to the measurement? so i dont get -15 db output from the filter...
I got no headroom on my setup with this filter...

How can i make the timealignement without changing the frequency responce?

i would love to just do timealignment only on my setup.
 

juicehifi

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You do not get -15 dB output from the filters here. Look at the correction filters to examine gain loss. I’m m guessing around 7-8 dB here.
 

peelbone

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Okej you are probaly right.
the problem here is that i need to set headroom of atleast -3db in roon so the signal wont clipp during playback.
At this point i have practicaly lowered the expected volume with -10db wich is a bit much for me.

is there an option not to lower db and still get timealign?
 

juicehifi

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You could try the Audiolense convolver. It rund for free in ca 3 months. In Audiolense convolver you can take monitor for digital clipping and even amplified the signal if you want to. Often you cannset the volume to +3-4 dB without getting any clipping.
 

peelbone

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What is Audiolense convolver?

i can still use roon?
 

Omid

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This tripped me for a while too. My understanding is that your rate limiting step is not how high your frequency curve goes but how low it dips. You could crank up your sub even more, it wouldn't make your loss any worse (AL would just dial down your sub, but not the mains).

Imagine you're playing a signal at full volume (0dBFS). Your main speaker speaker would dip down at ~260Hz (based on the filtered curve you posted). If you simply boosted 260Hz, you'd have a signal above 0dBFS, which would clip. There is no way to have a flat response curve, unless you lower the whole signal down to match the dip.

If I've understood correctly how AL works, when you say 10dB boost, AL lowers the whole signal by up to 10db (7-8 dB in your case), and then boosts the dips to get a reasonable flat response, without clipping. Try dialing a 30dB boost in AL, you'll see the replay volume won't come out that different, because AL judges that it only needs 7-8 dB to give you a flat curve.

In short, you can't have your cake and eat it too: impose a target that implies signal attenuation, use an imperfect speaker with highs and lows, and expect an unattenuated flat response.

You can mitigate the problem by making sure your DAC voltage output at 0dBFS matches exactly your amp or pre-amps' input sensitivity. Ideally, you have an amp with high gain and/or a speaker that's sensitive so the loss of 7-8dB still allows you to play as loud as you wish.
 
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juicehifi

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^^ Audiolense is a convolver. It appears as a sound card in Roon, so yes, the two can be used together.
 

peelbone

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This tripped me for a while too. My understanding is that your rate limiting step is not how high your frequency curve goes but how low it dips. You could crank up your sub even more, it wouldn't make your loss any worse (AL would just dial down your sub, but not the mains).

Imagine you're playing a signal at full volume (0dBFS). Your main speaker speaker would dip down at ~260Hz (based on the filtered curve you posted). If you simply boosted 260Hz, you'd have a signal above 0dBFS, which would clip. There is no way to have a flat response curve, unless you lower the whole signal down to match the dip.

If I've understood correctly how AL works, when you say 10dB boost, AL lowers the whole signal by up to 10db (7-8 dB in your case), and then boosts the dips to get a reasonable flat response, without clipping. Try dialing a 30dB boost in AL, you'll see the replay volume won't come out that different, because AL judges that it only needs 7-8 dB to give you a flat curve.

In short, you can't have your cake and eat it too: impose a target that implies signal attenuation, use an imperfect speaker with highs and lows, and expect an unattenuated flat response.

You can mitigate the problem by making sure your DAC voltage output at 0dBFS matches exactly your amp or pre-amps' input sensitivity. Ideally, you have an amp with high gain and/or a speaker that's sensitive so the loss of 7-8dB still allows you to play as loud as you wish.

Okej!
This is good info!
My dac has several gain settings: -6db (1,7 vrms) -3db (2,4vrms) 0db(4,1vrms) +3db(4,8vrms) +6db(6,8vrms).

My preamp has sensitivity 2.0 v so i guess -3db is best for it with out AL XO filters.
So if Al XO filter makes my gain 7-8db lower + headroom in Roon -3db i can safely switch output on my dac to + 6db?
 

peelbone

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Thanks alot =)
 

Badbruno

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Okej!
This is good info!
My dac has several gain settings: -6db (1,7 vrms) -3db (2,4vrms) 0db(4,1vrms) +3db(4,8vrms) +6db(6,8vrms).

My preamp has sensitivity 2.0 v so i guess -3db is best for it with out AL XO filters.
So if Al XO filter makes my gain 7-8db lower + headroom in Roon -3db i can safely switch output on my dac to + 6db?
Why not set your gains up at the Std 0 db across the board. If you have a multi meter you could set it such that preamp and amp gives you max gain without clipping .. then you won’t be leaving head room on the table
 
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