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post #1 of 5 Old 12-04-2019, 07:53 AM - Thread Starter
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subwoofer - crossover - delay ?

I have 2 separate systems for HT and music. In my HT system the receiver handles the subwoofer delay/phase. I am trying to find a way to integrate my subwoofer into my 2 channel preamp.

Sub-woofer is a IB powered by a behringer ep4000

1. I presume I can use the distance setting in my integra to adjust my phase/delay on the sub? I am using it to crossover the low end to the sub now and have a fbq 2496 to equalize it

2. for my 2 channel preamp I am trying to find out how to add it in. My plan was continue to use the XLR outs to power the main speakers via its power amp. and use the rca outputs to the sub. I was thinking of getting a minidsp so i can add the low pass crossover for the subs. the plan is to use the sub to compliment the low frequencies since I dont wnat to crossover the mains as they can go pretty low on their own.

Do i need to worry about delaying the mains to match the sub if my crossover is below 50hz? I see that the minidsp has a delay but that is just for the sub and I cant use it to delay the mains unless I put it in between the preamp and the main channel power amp?

I was trying to avoid an additional layer of AD-DA conversion

Can I just use the minidsp to adjust the phase of the sub and ignore any time delay that might be needed? My subs are about 5 feet further away from the MLP than my 2 main speakers.

Is there a good guide on how to use REW or any other application to check phase?
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post #2 of 5 Old 12-04-2019, 07:17 PM
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Polarity, delay, phase and PEQ are 4 different things.

If the subs are closer to the listener than the speakers, then you only need to add delay to the subs.
If they are further away than the speakers, then the speakers will need to be delayed, which will impact sound quality since you'll have to drop out of direct-mode or analog-direct mode.

and if they are the same distance away, then no delay should be required (unless you want to play with that to avoid room-mode nulls in some rare-r cases.)

The polarity of the subs and speakers should match. i.e. all drivers push out and the same time, and pull in at the same time.

REW cannot auto-suggest phase correction, but it can chart it.
You'd have to use rephase for that, and probably not all the miniDSP models support that? (and the Behringer's definitely don't since they lack FIR, i.e. IIR only.)

If you don't set the subwoofers LPF to match the natural rolloff (or HPF) of the speakers, then you'll have overlapping double-bass. Which may or may not be a problem.

If you had bought the DCX instead of the FBQ or DEQ, you'd be able to do HPF's (to 20hz), but it's too late for that now.
The miniDSP is better anyways...
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post #3 of 5 Old 12-05-2019, 08:24 AM - Thread Starter
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Quote:
Originally Posted by BassThatHz View Post
Polarity, delay, phase and PEQ are 4 different things.

If the subs are closer to the listener than the speakers, then you only need to add delay to the subs.
If they are further away than the speakers, then the speakers will need to be delayed, which will impact sound quality since you'll have to drop out of direct-mode or analog-direct mode.

and if they are the same distance away, then no delay should be required (unless you want to play with that to avoid room-mode nulls in some rare-r cases.)

The polarity of the subs and speakers should match. i.e. all drivers push out and the same time, and pull in at the same time.

REW cannot auto-suggest phase correction, but it can chart it.
You'd have to use rephase for that, and probably not all the miniDSP models support that? (and the Behringer's definitely don't since they lack FIR, i.e. IIR only.)

If you don't set the subwoofers LPF to match the natural rolloff (or HPF) of the speakers, then you'll have overlapping double-bass. Which may or may not be a problem.

If you had bought the DCX instead of the FBQ or DEQ, you'd be able to do HPF's (to 20hz), but it's too late for that now.
The miniDSP is better anyways...
thank you. i will look up rephase as I am not aware of this

"REW cannot auto-suggest phase correction, but it can chart it" what fuction of REW do i need to research to be able to see this? i assume once i get this i play with delay a little and rechart untill it matches?

My subs are a little further away than the speakers. I was reluctant to add the minidsp in the loop between the preamp and the poweramp for the main speakers. I asume that the AD-DA conversion would further color/distort the sound and was trying to avoid that in the main speakers that would defeat the point of a high quality DAC for my source flac music. Am I wrong in this though process?
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post #4 of 5 Old 12-05-2019, 09:03 AM
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Quote:
Originally Posted by thejck View Post
thank you. i will look up rephase as I am not aware of this



"REW cannot auto-suggest phase correction, but it can chart it" what fuction of REW do i need to research to be able to see this? i assume once i get this i play with delay a little and rechart untill it matches?



My subs are a little further away than the speakers. I was reluctant to add the minidsp in the loop between the preamp and the poweramp for the main speakers. I asume that the AD-DA conversion would further color/distort the sound and was trying to avoid that in the main speakers that would defeat the point of a high quality DAC for my source flac music. Am I wrong in this though process?


The 2x4 hd is the only minidsp that uses FIR filters btw.

If your subs are relatively close to same distance, I’t try running without delay first before complicating the system.

Chris
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post #5 of 5 Old 12-05-2019, 07:57 PM
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Quote:
Originally Posted by thejck View Post
My subs are a little further away than the speakers.
That's a problem for analog systems.

Quote:
Originally Posted by thejck View Post
what fuction of REW do i need to research to be able to see this?
The phase chart is the first tab in REW.
Phase coherence will also show in the impulse tab.
Room modes / nulls show up in the FR and waterfall decay tab.

Quote:
Originally Posted by thejck View Post
I was reluctant to add the minidsp in the loop between the preamp and the poweramp for the main speakers. I asume that the AD-DA conversion would further color/distort the sound and was trying to avoid that in the main speakers that would defeat the point of a high quality DAC for my source flac music. Am I wrong in this though process?
I won't say that it won't or can't, but it will be very small, if audible at-all.
All you can do is try it.

If you get the Emotiva XSP-1, each analog output is always-on and discretely-powered to avoid exactly this sort of thing, it's an all-analog fully-balanced fully-differential design.

Fully-differential systems cost twice as much to make because there is two of everything, which is then used to cancel the common mode noise, from end-to-end.

Their reference line is basically two DAC's, two pre-amps and two amps PER channel. i.e. 4 of them for stereo.

The common mode noise is rejected at each stage of the separates end-to-end.

Two input op-amps PER channel, two synchronized volume controls PER channel, four wires PER channel, and two output op-amps PER channel.

Cheaper systems deferentially sum the XLR at the input and re-calculate it at the output, which is a cheaper/crappier design. Or worse, disregard half the signal completely!
This is why the XSP-1 is so special and highly regarded for SQ.

That's why I bought one.

It's also flat from 1hz to 96khz, or better. I've measured it!

I can tell you that if you find the XSP-1 in any way distorted, it isn't the XSP-1's fault, it's something else in your system. It easily hangs with the best Classe, Bryston, Krell or McIntosh, and DAC components etc... if not beats them.

Worth buying if you are concerned about such things...

Last edited by BassThatHz; 12-05-2019 at 08:09 PM.
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