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Help to align Genelec 8341's with standard pair of subwoofers

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Sparky

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half a metre. Can't really go back any more than that.
 
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It's ok. It's just my room and I have to accept it. No point in dwelling on something I have no control over.

Moving on........:D
 

abdo123

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The phenomenon that is causing these dips and peaks is called Speaker Boundary interference response (or SBIR). basically at the low frequencies the speaker is omnidirectional and is radiating towards the back wall, the sound reflects from the backwall and arrives back at the listening position at the opposite phase and cancels the frequency. It can also arrive with indentical phase and cause a peak instead.

EsAdcJ0IVcvB4TjEg_NC1-qYQrOyvGvbZVvOTvFyvQMEY-c04jgkOtm7eeXKq_nYgHhrZmGDVkbyyTCN6Eafg4iutsrvsQYMjjTWT3P8OIcsSXa8omk16tnhj7tqbuoVjm2AoMHsXCSf3_U_Iw7esZjKTEtGxTiSFY_UPpB2y9uu0yg

1625587683266.png



at 1/4 wavelength you get a null, at 1/2 wavelength you get a peak, and so forth.

seems to match up quite nicely with your results. this effect can be minimized with bass traps (absorption panels) behind the speakers or by pushing the speakers further into the wall (preferably even in-wall mount them).

Note: same thing happens with the listening position, but it's called LBIR instead. people try to 'stack' the nulls of the SBIR with the peaks of LBIR. it can work to your advantage.
 
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The phenomenon that is causing these dips and peaks is called Speaker Boundary interference response (or SBIR). basically at the low frequencies the speaker is omnidirectional and is radiating towards the back wall, the sound reflects from the backwall and arrives back at the listening position at the opposite phase and cancels the frequency. It can also arrive with indentical phase and cause a peak instead.

EsAdcJ0IVcvB4TjEg_NC1-qYQrOyvGvbZVvOTvFyvQMEY-c04jgkOtm7eeXKq_nYgHhrZmGDVkbyyTCN6Eafg4iutsrvsQYMjjTWT3P8OIcsSXa8omk16tnhj7tqbuoVjm2AoMHsXCSf3_U_Iw7esZjKTEtGxTiSFY_UPpB2y9uu0yg

View attachment 139484


at 1/4 wavelength you get a null, at 1/2 wavelength you get a peak, and so forth.

seems to match up quite nicely with your results. this effect can be minimized with bass traps (absorption panels) behind the speakers or by pushing the speakers further into the wall (preferably even in-wall mount them).

Note: same thing happens with the listening position, but it's called LBIR instead. people try to 'stack' the nulls of the SBIR with the peaks of LBIR. it can work to your advantage.

That's really interesting and relevant info and it, like you say, matches up quite well to my scenario.
Unfortunately for me, I can't move my speakers enough to be able to cancel it out.
It is what it is I suppose. I've seen much worse frequency responses than mine!
 
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I'm having issues level matching my mains to my subs but thunder and lightning has stopped play here so I'll have to leave it here for now.

Ill post back soon.
 

abdo123

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I'm having issues level matching my mains to my subs but thunder and lightning has stopped play here so I'll have to leave it here for now.

Ill post back soon.

don't level match them, gain match them :).

otherwise either the subwoofers or the mains will be overdriven.
 
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don't level match them, gain match them :).

otherwise either the subwoofers or the mains will be overdriven.

I don't understand the difference? :D

I'll explain what I did and maybe you can pick it apart?

Before running GLM, I set my SHD to -30 volume as I feel that would be a good 75db starting point.

I then ran GLM as full range and as independent speakers.
I saved the calibration.
I then ran an SPL calibration and set it to 75db and confirmed it.
Uploaded the results to my speakers and removed GLM from the system.

I set up SHD routing as was suggested on page one.
Set all sliders to zero and ensured no crossovers or PEQ was active.

I then set up my umik1 with REW.

I then tested SPL using my umik1 and REW and it was down at 69db.

I checked the subwoofer SPL and that was down quite a bit too!
Bear in mind, I've had these two subs for years and have previously set their individual levels with the gain dial on the rear.

I'm not sure what happened but it isn't right.

Can't do anything with it right now though. :(
 

abdo123

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I don't understand the difference? :D

I'll explain what I did and maybe you can pick it apart?

Before running GLM, I set my SHD to -30 volume as I feel that would be a good 75db starting point.

I then ran GLM as full range and as independent speakers.
I saved the calibration.
I then ran an SPL calibration and set it to 75db and confirmed it.
Uploaded the results to my speakers and removed GLM from the system.

I set up SHD routing as was suggested on page one.
Set all sliders to zero and ensured no crossovers or PEQ was active.

I then set up my umik1 with REW.

I then tested SPL using my umik1 and REW and it was down at 69db.

I checked the subwoofer SPL and that was down quite a bit too!
Bear in mind, I've had these two subs for years and have previously set their individual levels with the gain dial on the rear.

I'm not sure what happened but it isn't right.

Can't do anything with it right now though. :(


I would start by getting everything restored to defaults, and then try to get the speakers to generate 75 dB @-30 dbfs (I'm sure one of the sliders on the back do that or via GLM). Use pink noise @ -30 dBFS (80Hz to 20KHz) for the calibration via the generator function. Make sure that the VU meters on the outputs in the MiniDSP show -30 dBFS as well during this procedure (it's actually -22 dBFS in REW generator for me on the 2*4 HD).

then what you would want to do is match the gain of the speakers to the gain of the subwoofers. Start by doing an SPL sweep on one of the Genelecs, then pick up one of the subwoofers and temporarily swap locations with the genelecs, keep doing sweeps and fidling with the gain knob of the subwoofer till you get the same exact curve as the genelecs (same dB / loudness).

when everything is gain matched do the alignment, then do Dirac calibration. and voila! reference quality system.
 
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I would start by getting everything restored to defaults, and then try to get the speakers to generate 75 dB @-30 dbfs (I'm sure one of the sliders on the back do that or via GLM). Use pink noise @ -30 dBFS (80Hz to 20KHz) for the calibration via the generator function. Make sure that the VU meters on the outputs in the MiniDSP show -30 dBFS as well during this procedure (it's actually -22 dBFS in REW generator for me on the 2*4 HD).

then what you would want to do is match the gain of the speakers to the gain of the subwoofers. Start by doing an SPL sweep on one of the Genelecs, then pick up one of the subwoofers and temporarily swap locations with the genelecs, keep doing sweeps and fidling with the gain knob of the subwoofer till you get the same exact curve as the genelecs (same dB / loudness).

when everything is gain matched do the alignment, then do Dirac calibration. and voila! reference quality system.

Thank you abdo! :)

I hate having to ask on these forums as I'm sure you're all sick of us inexperienced guys constantly asking questions!

Next time I'm able to have another go at it (I've a wife and two kids), I'll follow your instructions and see where it leads me. :)

Thanks again mate.
 
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Just a quick question.

The image below is a measurement taken of both my mains playing together.
Why does it look so awful? Huge peaks and dips everywhere whereas the individual speaker measurements look fairly good.
Is this what I'm hearing or is it not accurate?
This is a single point, full range measurement taken at the MLP.

I thought the GLM software is supposed to fix things like this?

Using the alignment tool in REW, I was able to flatten it out quite significantly but is this something I should be doing?

2021-07-06 (2).png
 

richard12511

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Just a quick question.

The image below is a measurement taken of both my mains playing together.
Why does it look so awful? Huge peaks and dips everywhere whereas the individual speaker measurements look fairly good.
Is this what I'm hearing or is it not accurate?
This is a single point, full range measurement taken at the MLP.

I thought the GLM software is supposed to fix things like this?

Using the alignment tool in REW, I was able to flatten it out quite significantly but is this something I should be doing?

View attachment 139581

You may have a phase alignment issue around the crossover. I’m not at my computer at the moment, but Google “REW phase alignment tool”. There are YouTube videos showing how to do it. Watch a couple of those. Basically, you measure sub(pair) and left or right speaker with sweep, then tell REW where your crossover is by clicking on the line in the graph. REW will then give you a delay in ms to add to the miniDSP that will phase align your two subs to the monitor you chose at the crossover frequency.
 
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You may have a phase alignment issue around the crossover. I’m not at my computer at the moment, but Google “REW phase alignment tool”. There are YouTube videos showing how to do it. Watch a couple of those. Basically, you measure sub(pair) and left or right speaker with sweep, then tell REW where your crossover is by clicking on the line in the graph. REW will then give you a delay in ms to add to the miniDSP that will phase align your two subs to the monitor you chose at the crossover frequency.

Hi Richard.

Thank you. I'll do just that.

I wish all this wasn't so complicated. I'll get there in the end though.

Mike.
 
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That is the one big benefit of the otherwise-overpriced GLM subs. They eliminate all complications(for stereo configurations, at least).

So very true.

Good business strategy to be fair, give you a product which gets you 80% of the way there and offer an (expensive) item to complete the package....:(
 
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Ok guys.

I think I need an idiots guide on how to do this correctly.
I will post what I think I need to do and hopefully, somebody who has the knowledge, time and inclination to help me will follow it up. :(

1. Set my volume within the SHD to a level I feel is suitable at 75db (I usually set it to -20 ) giving me 20db of headroom before the SHD reaches zero on the volume display.
2. Ensure the routing within the SHD is set correctly and that there are no filters applied.
3. Reduce the levels slightly on the output volume sliders to around -5db below zero to allow me to increase the output volume individually for each driver with headroom to spare.
4. Run the GLM software - Set to full range - Individual measurements - confirm calibration - set volume level to 75db - store to speakers.
5. Pack away GLM and mic then fire up REW with Umik1.
6. Measure Left and Right mains individually full range using one of the speakers as a reference.
7. Cry at the crap response.
8. Gain match my subs (I always set them to be 10db above my mains to allow for headroom to adjust for EQ.
9. Measure my subs individually 0-120hz
10. Ensure the subs sum well together (which they do).

That's as far as I've got at the moment.

I don't know how to select the best crossover?
One sub is next to the couch at MLP and one is up front near the right speaker. Does this even matter as they are playing as one together.
My room is NOT symmetrical.
My right speaker is in a corner my left is more in the open but both are close to a wall.
I'm confused about this FDW window that I can't get my head around.
Any guidance for a total NOOB would be great!!

Sorry for all the questions!
 

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Any guidance for a total NOOB would be great!!

Sorry for all the questions!

So, I haven't used a miniDSP and I can't answer your questions about specific steps in their UI. However, you're aware they have a bunch of step by step tutorials on their site right?

eg: single sub with REW/Dirac, dual sub with Multi-Sub Optimizer

I would consider GLM a separate optional step entirely, as REW/Dirac will just see the GLM-corrected response and as far as it's concerned that's just the speaker's normal response.
 
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So, I haven't used a miniDSP and I can't answer your questions about specific steps in their UI. However, you're aware they have a bunch of step by step tutorials on their site right?

eg: single sub with REW/Dirac, dual sub with Multi-Sub Optimizer

I would consider GLM a separate optional step entirely, as REW/Dirac will just see the GLM-corrected response and as far as it's concerned that's just the speaker's normal response.

Hi.

I'll check that out. Thank you.

I'm not intending to use DIRAC as I want to keep things as simple as possible. DIRAC came "free" with the SHD otherwise, I wouldn't have paid for it to be honest.
Used DIRAC before and wasn't a fan of it.
 

Sancus

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I'm not intending to use DIRAC as I want to keep things as simple as possible. DIRAC came "free" with the SHD otherwise, I wouldn't have paid for it to be honest.
Used DIRAC before and wasn't a fan of it.

In both cases the Dirac step is after everything else so you can just ignore it then.
 

abdo123

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@Sparky

We can't see the messiness of the combined response of the two mains if we don't see the response of the speakers separately.

I would also take GLM out of the equation, completely. If you don't need to use it to set the gain of the speakers then just don't use it at all. the response of the subwoofers NEEDS to be corrected. GLM doesn't do that.

Go through the steps i mentioned, If something isn't clear for you then feel free to ask questions. Because right now I feel like you're just going in circles and wasting your time. If you're uncertain about crossover frequency just do 120Hz then.

Also don't put the gain of the subwoofers 10 dB louder, no reason for that at all keep all 4 matched.
 

abdo123

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I'm not intending to use DIRAC as I want to keep things as simple as possible. DIRAC came "free" with the SHD otherwise, I wouldn't have paid for it to be honest.
Used DIRAC before and wasn't a fan of it.

Then I would sell the MiniDSP SHD and the subwoofers you have and buy Genelec subwoofers, as without Dirac there is no correction applied to the subwoofers.

That's really the only way to keep things simple if you don't want to use Dirac.
 
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