Need some help for my room correction

[pjug]

I think it will be a bit hard to make so (WAF - Picture of the current positionning of my right speaker - the left one is on the other side of the piano).
But it is very interesting and I enjoy to learn about that. To apply as soon as I live in a bigger place

Maybe the photo is deceiving, but it looks like you could move the speaker away from the wall without much effect on the use of the room..

 

[Max]

SBIR is physics. It's determined by the distance that the speakers are from the front wall. Plugging the ports may help a little with the port tuning freq.

Great, I will make a try.
I've just looked for my previous measurements (with and without the dedicated foam addons) but it seems I deleted them... I hope I'll able to measure it again soon.

 

[AdamG]

This is going to sound wrong in so many ways. Pull it out a little bit at a time. Maybe an inch and leave it a few days. It the Wife does not notice. Move it another inch. Just keep creeping it out until it sounds better.

Lovely decor BTW, they are nice looking stands and kinda multifunctional.

 

[Hipper]

You can always move speakers out to a listening position and then back when not in use.

 

[abdo123]

I think it will be a bit hard to make so (WAF - Picture of the current positionning of my right speaker - the left one is on the other side of the piano).
But it is very interesting and I enjoy to learn about that. To apply as soon as I live in a bigger place

Can’t you just hang a pannel behind it?

 

[Max]

Maybe the photo is deceiving, but it looks like you could move the speaker away from the wall without much effect on the use of the room..

You're totally right! Because it is ... the right speaker (little joke). In pratice, the positionning of the left one is more tricky because almost on the way.

But I could move them without any problem just for the time of my listening sessions. If so, would it solve the SBIF issue ?
Actually, in my previous measurement (those I deleted ...), I also tested and measured the speakers a big step away from the wall (1.5m I guess) and there were almost no difference in the bass bump area (0-300Hz). But I didn't look above.

 

[Max]

Can’t you just hang a pannel behind it?

Indeed, I could - even just for the time of the listening session.

 

[abdo123]

You're totally right! Because it is ... the right speaker (little joke). In pratice, the positionning of the left one is more tricky because almost on the way.

But I could move them without any problem just for the time of my listening sessions. If so, would it solve the SBIF issue ?
Actually, in my previous measurement (those I deleted ...), I also tested and measured the speakers a big step away from the wall (1.5m I guess) and there were almost no difference in the bass bump area (0-300Hz). But I didn't look above.

That’s impossible. Are you sure?

 

[Max]

Pull it out a little bit at a time. Maybe an inch and leave it a few days. It the Wife does not notice. Move it another inch. Just keep creeping it out until it sounds better.

I love this way of doing! I'll do it and test step by step

Lovely decor BTW, they are nice looking stands and kinda multifunctional.

Oh, thanks. Homemade. They fitted perfectly to my previous speakers, but it is still fine with the new ones and I have now a small extra place to tilt the speakers

 

[Max]

That’s impossible. Are you sure?

I am actually almost quite sure about that because I remember I was myself very surprised by this outcome. Definitively, I have to make this measure again. And before, I could first use a simulation tool like the "Room simulation" of REW. Do you think it could be useful?

 

[alex-z]

Are we looking at the same graphs? I saw 20dB elevated low frequencies in a clump which indicates proximity to boundaries. Or did I miss the "after" graphs?

The peaks and nulls are definitely caused by room issues. But the sharp rolloff after 40Hz gives me good reason to suspect the port tuning coincides with a room mode. Cutting 10-20dB from the entire bass region will likely sound unnatural, but making a small cut to fix the port tuning bump should be fine.

 

[alex-z]

Indeed, no subwoofer used. I don't have any for the moment but I had wondered about it a while ago, so why not in the future and maybe in a near future. So, you recommend to add a sub and cross at 80Hz. Why not adding a sub without crossing? I thought there was some benefits to multiply source of bass frequencies in the room (to reduce the resonances related to the room).

Because if you add the subwoofer without the crossover, you aren't solving any of the issues that a subwoofer is intended to fix.

Speakers would still be playing low, and adding distortion.

You have too much bass already, you want less of it, but hitting a lower frequency.

Multiple subwoofers throughout the room is an effective way to reduce room mode issues. With speakers, where the room modes aren't a problem may have bad imaging, bad wife acceptance, non-symmetry, etc. Subs have more placement flexibility because they only play 1-2 octaves of bandwidth.

 

[Max]

You have too much bass already, you want less of it, but hitting a lower

I thought adding a subwoofer without crossing could already kill the room modes and so, kill the bass bump (then just adding a small EQ in low frequencies to compensate this added LF energy). Even if I suppose positionning one sub only to kill several modes should really be a hard task, to not say a lottery.

Setting up a crossfit seems a bit complex and maybe out of my budget (buying a sub is ok but buying a multichannel dac should be too much). Anyway I keep in mind these good advices

 

[alex-z]

I thought adding a subwoofer without crossing could already kill the room modes and so, kill the bass bump (then just adding a small EQ in low frequencies to compensate this added LF energy). Even if I suppose positionning one sub only to kill several modes should really be a hard task, to not say a lottery.

Setting up a crossfit seems a bit complex and maybe out of my budget (buying a sub is ok but buying a multichannel dac should be too much). Anyway I keep in mind these good advices

Most subs have a crossover built-in that you can use.

If you add the subwoofer without a crossover, some room modes may improve, but others may worsen. You remain at the mercy of your speaker positioning, rather than simply being able to move the subwoofer and obtain a better response.

Additionally, having the crossover reduces the distortion of your speakers. Not just in low frequencies, but also mid-range, due to intermodulation distortion.

You are already beyond "small EQ". Rather than adding weight to a sinking ship and requiring a bigger fix, adding subwoofer(s) is a proper solution. All the best setups run multi-sub these days, as physical acoustic treatment like mineral wool is not cost effective in the 20-80Hz region.

 

[Max]

Most subs have a crossover built-in that you can use.

Oh, I knew the crossover at the input of the sub (to shape the signal to drive the sub) and I've indeed seen output plugs; but I believed it was just the duplicated signal of the input one (so, the fullrange signal). If I get it well, this output may also be the complementary of the crossover (that is to say the fullrange signal minus the low frequencies) to address the main amplifier for the speakers. Am I right?

If so, indeed, it seems easy to set up. But if so, are there some possible unexpected degradations of the signal to the main speakers? In terms of THD or SNR. Even if I would be surprised if these possible degradations had more impact on the listening than my room modes.

Thanks again for your answers

 

[alex-z]

The output from the sub is no longer full-range, everything below the crossover setting stays with the sub. Usually a second order slope (12dB per octave).

There are both low and high level crossovers, depending on what sub you buy. I use low level when possible, no sense having the speaker amp waste power on frequencies that the speakers won't be playing anyway.

I am sure there is some measurable reduction in SNR, but nothing audible. The crossover distortion will be hidden in the distortion of the subwoofer itself, even extremely good models exceed 1% THD at high volume. Although given the limits of human hearing, 1% THD at 80Hz is irrelevant.

 

[Max]

The output from the sub is no longer full-range, everything below the crossover setting stays with the sub. Usually a second order slope (12dB per octave).

Perfectly clear, understood.

I am sure there is some measurable reduction in SNR, but nothing audible. The crossover distortion will be hidden in the distortion of the subwoofer itself, even extremely good models exceed 1% THD at high volume. Although given the limits of human hearing, 1% THD at 80Hz is irrelevant.

I thought more about the degradation of the signal of the output (to the main speakers). But I suppose your explanation is still fully valid. Now, I have to take a look at the subwoofers .... and to balance with WAF .

Thanks again for all these advices. A lot of things to try .

 

[ernestcarl]

(NB: I've tried to tune the phase, too, with the Paragraphic Phase EQ, but the phase is too messy and I've never succeeded to get good results, so I give up)

Try the second tab called "Filters Linearization" and play with the numbers -- it may significantly reduce the number of filters needed in the paragraphic phase EQ.

Exporting the impulse file (65536 taps, the right sample rate) and uploading into the convolver

Maybe that's a bit too many taps. Try 16,384 if your EQ'ing down low in the bass. The correction would be "fuzzier" the lower you go, but that extra bit of precision may not be so important down there anyways... I only use 2048 taps now primarily for phase correction and and still am getting as good an "alignment" as possible -- with the "textbook" step responses now as well.

All other PEQs duties are simply relegated to another EQ program elsewhere. Figuring out how to best fiddle with the time domain, esp. with multichannel setups manually can be a rather complicated undertaking. I would relegate it as something that can be done much, much later if bored out of your mind.

But you have to learn how to use frequency dependent windowing (FDW) to clean and smooth out the phase responses. In an untreated living room -- and with multi-way speakers -- I know it can get pretty messy there... It's in the first button beside "dB SPL 83" of REW. As well as export (may be better from average data) the phase and/or excess phase into rePhase.

... Sometimes the phase can look wonky because of the unavoidable room and placement -- after some EQ it goes back to looking normal -- don't exactly know why this happens, but I suffer from something similar and the phenomenon is very measurable and repeatable.

See the anomaly of the HF:

It's very odd, but it is also very consistent/repeatable. Only after applying my HF shelving EQ's seems to do the trick (match with the opposite channel) for whatever reason.

 

[Max]

Try the second tab called "Filters Linearization" and play with the numbers -- it may significantly reduce the number of filters needed in the paragraphic phase EQ.

Actually, I tried to use the "Filters Linearization" several times. I thought it would have been simple because I know the specifications of the filter of the speakers. But it never worked

 

[Max]

But you have to learn how to use frequency dependent windowing (FDW) to clean and smooth out the phase responses. In an untreated living room -- and with multi-way speakers -- I know it can get pretty messy there...

I had indeed problems to work with the FDW in REW. I followed a tuto to make the MMM measurements and to shape the measures but I wasn't totally sure about my doing. If you could suggest a link that describes and explains this part, it would be great. I could maybe make another try