Can anyone help with Alignment?

[Robbie010]

A little update.

The new tweeters arrived and were installed yesterday, I decided to re-work each of the driver EQ's and crossovers, as the Lpads had an effect. I now have decent extension above 12khz and have started to integrate the subwoofer but I'm still really struggling with alignment.

I can't really do anything about the 33hz room peak, wondering whether I should add a PEQ to knock it down some.

It looks like I need to do some work at the 80hz and 1.2khz crossover to deal with the dips.

 

[levimax]

I can't really do anything about the 33hz room peak, wondering whether I should add a PEQ to knock it down some.

Yes, minimum phase cuts of LF peaks is one of the best uses of DSP. It will correct both amplitude and phase and cure audible issues.

 

[dualazmak]

I believe the Fq-SPL curve in your above post #241 was measured at your listening position, right?

I can't really do anything about the 33hz room peak, wondering whether I should add a PEQ to knock it down some.

It looks like I need to do some work at the 80hz and 1.2khz crossover to deal with the dips.

What would be the reason/cause of the 490 kHz dip? Just a simple room mode?

 

[Robbie010]

I believe the Fq-SPL curve in your above post #241 was measured at your listening position, right?


What would be the reason/cause of the 490 kHz dip? Just a simple room mode?

Yes, very astute.

I’m not quite sure what causes the 490hz dip, it must be a room reflection. .

.

 

[dualazmak]

I’m not quite sure what causes the 490hz dip, it must be a room reflection. .

If it would be really so, I suggest you trying suitable and enough sound absorbing material(s)/treatment(s) on the wall (windows) behind the SPs and/or behind your listening position, prior to your possible efforts on DSP-EQ-ing the 490 Hz dip.

If you presently do not have, additional sound absorbing carpet(s) and/or thin mattress on the floor may be also worthwhile to be tried, I guess.

My post here #687 would be of your reference and interest in this perspective, I assume;
- Not only the precision (0.1 msec level) time alignment over all the SP drivers but also SP facing directions and sound-deadening space behind the SPs plus behind our listening position would be critically important for effective (perfect?) disappearance of speakers: #687

 

[Robbie010]

Thanks gents.

I have done some shopping today and will try some basic acoustic absorption panels as suggested.

I also spent a few hours re-working the sub. After doing some basic measurements earlier today I realised that that the sub was just reinforcing the room mode and I needed to cut to the speakers and just let the sub do low bass.

Here are todays results:

Getting there slowly.

 

[dualazmak]

Looks much better, at least in Fq-SPL response!
What is your subjective listening impressions now using typical reference music tracks like these ones?

 

[dualazmak]

My another suggestion for you, only if you are capable thereof, is to move your listening position (sofa?) a little bit forward towards the SPs to make the "vertex angle at listening position" of the "isosceles triangle" more than at least 37 degree.

In your diagram, presently the angle is about 25 degree, right?

 

[3ll3d00d]

Thanks gents.

I have done some shopping today and will try some basic acoustic absorption panels as suggested.

I also spent a few hours re-working the sub. After doing some basic measurements earlier today I realised that that the sub was just reinforcing the room mode and I needed to cut to the speakers and just let the sub do low bass.

Here are todays results:

View attachment 485537

Getting there slowly.

Is that a measurement of the L+R combined measured via one sweep? If yes the subwoofer level may measure 6dB higher than reality and the combined response will be similarly unnatural.

 

[Robbie010]

Is that a measurement of the L+R combined measured via one sweep? If yes the subwoofer level may measure 6dB higher than reality and the combined response will be similarly unnatural.

Yes, both speakers driven, one slightly longer sweep at 256k, measured at the seating position.

I assume this is a result of the room boundary effect?

 

[3ll3d00d]

Yes, both speakers driven, one slightly longer sweep at 256k, measured at the seating position.

I assume this is a result of the room boundary effect?

What is "this" in the above?

You want to measure l and r separately and overlay them

 

[Robbie010]

What is "this" in the above?

You want to measure l and r separately and overlay them

I’m referring to your comment that the subwoofer may measure +6db higher than reality, would this be due to the boundary effect?

Also, what does that mean in terms of the frequency response i.e. should I correct this effect by increasing the subwoofer output by 6db??

 

[3ll3d00d]

I’m referring to your comment that the subwoofer may measure +6db higher than reality, would this be due to the boundary effect?

No it's because an L+R sweep with a mono sub will send the same signal twice to the sub hence +6dB because double voltage

 

[Robbie010]

I’ll need to get my head around this……. It’s already hurting my brain…..

The subwoofer is connected to the left channel amplifier.

The left and right channel outputs are “linked” in the DSP Crossover, however, nothing is connected to the right channel amplifier.

Should I un-link the left/right subwoofer output?

That way the subwoofer will only receiver the left channel signal?

However, that would mean that the subwoofer would not receive any signal from the right channel, so when I try and run separate left / right channel sweeps in REW the sub would only play with the left channel!??

 

[Flaesh]

The link simply saves the user from entering settings into the linked channel.

 

[3ll3d00d]

I don't recall what dsp you are using nor do I understand what you mean by separate l and r amps in the context of an active speaker with a mono sub? Is it described in some earlier post?

But anyway I just mean run a sweep of the L channel and then run a sweep of the R channel. That's all.

 

[dualazmak]

The link simply saves the user from entering settings into the linked channel.

Sorry, but at least I myself cannot understand what you mean...
Which link(s) do you mean for what?

 

[Keith_W]

I don't recall what dsp you are using nor do I understand what you mean by separate l and r amps in the context of an active speaker with a mono sub? Is it described in some earlier post?

https://www.audiosciencereview.com/...anyone-help-with-alignment.66272/post-2414927

I don't understand what you are trying to do either, @Robbie010. This is how you should connect your channels:

For the subwoofer, get your software to sum the L and R channels (mono).

 

[Robbie010]

Good evening all!

I'm back at it now after a week working away, just picking up on this subwoofer connection query. I thought I would try and plot-out how I have the setup connected so that it makes sense when discussing:

So, currently the subwoofer is simply connected to input/output 1 of the left channel amplifier.

As mentioned previously, within the Crossover / DSP software I have the Left and Right channels Linked in pairs (1&2, 3&4, 5&6, 7&8), so that any changes to one channel are automatically applied to the other.

Each output channel has an input channel applied to it - 1, 3, 5 & 7 are Channel A (Left), 2, 4, 6 & 8 are Channel B (Right).

It seems I need to sum the signal of Output Channel 1 & 2 to the subwoofer.

Am I correct in thinking that I can do this by simply selecting both Input A & B at Output 1?

 

[Keith_W]

Yes, that's the general idea. But whether you can actually do that or not depends on how your software is configured.