Correcting below Schroeder, different target level

[markstein]

I think this is about as good as I can get it with speaker positioning alone. Var smoothing. The 125-300Hz region is a disaster but I think it must be the asymmetry of the room, considering the right side is much worse than the left. The side wall next to the left speaker is where I have my record shelves, which is likely helping with the first order reflections there, whereas the right side has nothing really in the way of absorptive or diffusing material. Will do some sweeps and see where I get with it.

The 100-300Hz region is the most difficult in most small domestic listening rooms - at least in my room which is very similar to your setup. There simply is no space to place the speakers 2m front the front wall. This is where a cardioid speaker could be really beneficial...

Another thought: when moving your speakers to optimize SBIR, do not forget that the same SBIR effect also applies for your listening position Moving your sofa has an effect as well.

 

[Good Vibes]

Measure their response close to the wall and you’ll see for yourself. In my experience, it brought life back into the sound that had been sucked out of it. My speakers are also rear ported and I had thought having them close to the wall would distort the sound or ruin sound staging, but I must say that I don’t pick up on any issues and the overall sound seems fuller and more complete.

 

[kyuu]

Thanks for the tips. I have not tried a position with the speakers very close to the rear wall as that's generally been taboo in my experience. They have rear facing ports and are already pretty bass-heavy so I didn't bother.

Ports should be fine as long as you leave a space roughly the diameter of the port (so usually a couple inches). You will get more room gain in the bass, but if you are doing room correction then you can knock those peaks back down and it essentially be free system headroom. Putting the speakers closer to the wall will shift the SBIR cancellations up in frequency and reduce their amplitude. I always like to defer to Genelec's diagrams on this topic:

 

[Keith_W]

Surely they meant distance < 0.6m.

 

[kyuu]

Huh, I never noticed that apparent typo before.

 

[-Matt-]

Surely they meant distance < 0.6m.

Huh, I never noticed that apparent typo before.

You can read that as saying...
If your speaker is more than 0.6m from the wall it can cause those dips (i.e. reduce the level of these frequencies).

(I did also find that quite confusing for a while when I first saw it).

 

[radialMelt]

Experimented a little more last night. Pushing the speakers super close to the back wall, as expected, boosted the entire bass region so that with some correction, the nulls around 125Hz and 200Hz were effectively negated. That said, a new, very significant null shows up around 250Hz which is more noticeable to my ear than the one at 200Hz. Not sure if I'm actually finding improvements here or just trading compromises. I will experiment some more this evening.

I also took some sweeps (5 per channel, averaged) to take a stab at correcting the phase in rePhase. It's so messed up I don't think I'll get anywhere with it, hah! Thankfully even without correction its all still very listenable.

Thanks for the advice all

 

[sigbergaudio]

You can read that as saying...
If your speaker is more than 0.6m from the wall it can cause those dips (i.e. reduce the level of these frequencies).

(I did also find that quite confusing for a while when I first saw it).

I think what they're trying to say is that if you place your speakers further away from the wall, the overall bass level will be reduced (due to reduced boundary effect).

 

[markstein]

My understanding: If you move your speakers >0.6m from the back wall, you are reducing bass level by huge dips caused by SBIR. The dips in upper bass/ lower midrange are less deep (and noticeable?) due to increasing directivity ar these frequencies (at least with large baffle speakers).
Makes perfect sense to me.

 

[raindance]

Experimented a little more last night. Pushing the speakers super close to the back wall, as expected, boosted the entire bass region so that with some correction, the nulls around 125Hz and 200Hz were effectively negated. That said, a new, very significant null shows up around 250Hz which is more noticeable to my ear than the one at 200Hz. Not sure if I'm actually finding improvements here or just trading compromises. I will experiment some more this evening.

I also took some sweeps (5 per channel, averaged) to take a stab at correcting the phase in rePhase. It's so messed up I don't think I'll get anywhere with it, hah! Thankfully even without correction its all still very listenable.

Thanks for the advice all

You can place absorption behind the speakers to attenuate this dip because it is higher in frequency and easier to treat than low bass.

 

[radialMelt]

You can place absorption behind the speakers to attenuate this dip because it is higher in frequency and easier to treat than low bass.

Yeah, that is what I would do in any other room like my studio for example. But sadly I don't have such an option in this particular room. You'd still want a good 30cm deep panel there to be effective. I just don't have the space (or the aesthetic tolerance.)

 

[raindance]

Aesthetic tolerance = accept compromised results. You just can't have your cake and eat it too. You just have to decide what acceptable looks like. In my case I also have an acoustically asymmetrical space and I have to accept that there are a few suck outs I just can't fix, but fortunately the result of both speakers compromises combined gives me a fair result. Oh, plus sub of course.

 

[radialMelt]

Aesthetic tolerance = accept compromised results. You just can't have your cake and eat it too. You just have to decide what acceptable looks like. In my case I also have an acoustically asymmetrical space and I have to accept that there are a few suck outs I just can't fix, but fortunately the result of both speakers compromises combined gives me a fair result. Oh, plus sub of course.

Agreed, I thought I'd made it clear that I am aware that I won't be able to get anywhere near "good" results if I'm not willing to re-arrange or treat the room. I'm not that naive

Originally the post was about handling the transition between a corrected bass region with a target level that differs from the target level of the upper, uncorrected region. We've gone off course to general advice territory, which is a-ok for me. Lots to learn here!

 

[raindance]

Agreed, I thought I'd made it clear that I am aware that I won't be able to get anywhere near "good" results if I'm not willing to re-arrange or treat the room. I'm not that naive

Originally the post was about handling the transition between a corrected bass region with a target level that differs from the target level of the upper, uncorrected region. We've gone off course to general advice territory, which is a-ok for me. Lots to learn here!

Yeah. Sorry. I tried the road you're going down years ago but used a sub that could go quite high and fixed a few nulls using that, pushed it's volume a bit and accepted the mains as they were above the sub frequency. But "high" was 150Hz. I suppose you could also try similar using mid bass woofers - Hsu used to make some - they're for this exact purpose.

I do think the active idea suggested earlier, feeding equalized audio to the bass drivers via a separate amp, could be good, but you'll probably need to also pass the tweeters through an EQ channel on order to match the delay introduced. But this will allow you to do at least some of the boost you require in the corrected range.

 

[radialMelt]

Ran a bunch more experiments this time focusing more on the distance to the rear wall as opposed to distance between speakers. Things change a little but no major "eureka" moments. I also took out some batting I'd shoved in the ports. This is MMM technique, 45 averages, var smoothing.

Still the same chaos between 100-300Hz. I've corrected (w/ PEQ in my miniDSP) up to about 1.4kHz and it's certainly helped with the overall presentation. It may not be accurate but its still very enjoyable to listen to.

 

[DWPress]

Sometimes you just get what you get after optimizing everything you can. It really doesn't look that terrible and you've made improvements, I've seen worse, as long as it sounds good to you. The back of the brain says "it can be better" because your eyes see all those peaks and dips. If the bass isn't boomy at 60hz and the bright upper frequencies are to your taste then live with it for awhile and enjoy your favorite music, after a few different sessions you may note where improvements can be made and revisit your EQ attempts.

 

[kyuu]

View attachment 499038

Still the same chaos between 100-300Hz. I've corrected (w/ PEQ in my miniDSP) up to about 1.4kHz and it's certainly helped with the overall presentation. It may not be accurate but its still very enjoyable to listen to.

I'm unclear: is that measurement with or without the PEQ applied? If the latter, then that's really not bad at all. Most of the deviations above the 100Hz are pretty high Q and so likely not very audible. A bit bright for my tastes but without correction it's difficult or impossible to get a really flat in-room response below 1kHz. If it sounds good to you then I wouldn't worry over much about what your eyes are seeing on the graph.

 

[radialMelt]

Apologies, those measurements are without PEQ applied. I had been experimenting with speaker positioning in attempt to improve on my previous measurements. I've not taken a measurement after applying PEQ yet.

 

[markstein]

Ran a bunch more experiments this time focusing more on the distance to the rear wall as opposed to distance between speakers. Things change a little but no major "eureka" moments. I also took out some batting I'd shoved in the ports. This is MMM technique, 45 averages, var smoothing.

View attachment 499038

Still the same chaos between 100-300Hz. I've corrected (w/ PEQ in my miniDSP) up to about 1.4kHz and it's certainly helped with the overall presentation. It may not be accurate but its still very enjoyable to listen to.

Looks pretty good.

I would try some PEQ to get the red peak between 100 and 200 Hz down a bit, as well as those heavy resonances at approx. 62 Hz and 80 Hz.

Leave everything above 400-500 Hz as-is, I.e. do not apply any correction above that range.

 

[DWPress]

In my earlier comment I hadn't realized that was without EQ so even better and compare that to your early posts! Take out the blue peak at 60Hz down to red level and maybe try a filter at 1k to take out that 5db peak that shows on both speakers but it might be cabinet resonance. Now is the time to measure them together from your LP - note that the 2 channels often are opposite each other on some of the nastier peaks. See how they sum together before doing any further drastic EQ separately on L & R channels.