Room challenge and DSP

[RayDunzl]

Illustrating FR from a different spot with IR is not really a good example.

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Did I do that?

 

[Krunok]

?

Did I do that?

That's how I got it. He was asking about FR from another saptial point and you showed 2 IR responses, which are showing response in time domain. Maybe if you explain in more detail what was your idea..

 

[Fluffy]

I was asking specifically about reflected sound. Say you have some hard surface that gives a delayed secondary peak and you somehow use DSP to correct that. that correction would only apply at one spot in the room, wouldn't it? At a different spot in the room the reflection would arrive at a different time and won't be cancelled out.

 

[Krunok]

I was asking specifically about reflected sound. Say you have some hard surface that gives a delayed secondary peak and you somehow use DSP to correct that. that correction would only apply at one spot in the room, wouldn't it? At a different spot in the room the reflection would arrive at a different time and won't be cancelled out.

Reflective surfaces won't be that much of a problem if your speaker has smooth off-axis response.

And yes, that kind of a correction is location specific. It get's more usefull if you average the response over your litening area instead of making single spot measurements.

Typically most of your corrections would be in the range below Schroeder frequency (app 300Hz in "normal" rooms) to correct for room modes. Corrections above that range mostly would be to adjust to your favorite listening curve and, to some extent, to specific absorption characteristics of your room in the MF and HF range. But once again, be aware that with DSP you cannot rectify non-linear off-axis response of your speakers - that should be done by design.

 

[Fluffy]

I have never tried to use room correction for a couple of reasons. First of all, currently I have active monitors at nearfield distance (about 1m) when sitting by the computer, so I don't really see much point. The second is that when I listen to music I sometimes like to move around and not sit "with my head in a vice" (as Paul Mcgown likes to say).

Is room correction relevant to those two situations?

 

[mitchco]

As @Krunok mentions, it depends. Some DSP products are better than others. Some use multiple multiple analysis measurements, some use a single measurement but a different algorithm (using superposition) to not fill in all of the dips, but rather halfway...

In the case of the DSP software I use, both the frequency and timing response stays more or less the same across a 6 ft x 2 ft area that represents my couch. I took 14 measurements within that area and overlaid them in REW. Documented in my sig. So no, if the speaker has smooth on and off axis response, it is not just for point in space. I use constant directivity speakers and I can move anywhere on my 3 seat six foot couch some 3 meters away from the speakers in an equilateral triangle and both the frequency and timing response stays more or less the same. No head in vice here.

In your situation, the first step is to use a calibrated measurement mic and REW to see what kind of response you are getting.

 

[Ron Texas]

@ahofer your home is beautiful and you have lovely furniture, but you need to rearrange things if you want more than casual background sound. Those speakers need to be in front of where you sit, not behind. The way things are right now, EQ is premature. One speaker is close to a side wall the other is far away. That doesn't make for good imaging. My guess is place them on either side of the fireplace, rotate the couch a bit to get in front of them and hope nobody else complains. Next step is get a calibrated microphone like a UMIC-1 and learn how to use REW. You don't need any additional hardware because once the necessary EQ is determined it can be applied in many software players. For example JRiver has a built in parametric equalizer.

As an alternative to room treatments you may be able to acquire woven items to hang on the walls and some nice drapes for the windows. I have one of those benches, by the way.

 

[ahofer]

@ahofer your home is beautiful and you have lovely furniture, but you need to rearrange things if you want more than casual background sound. Those speakers need to be in front of where you sit, not behind. The way things are right now, EQ is premature. One speaker is close to a side wall the other is far away. That doesn't make for good imaging. My guess is place them on either side of the fireplace, rotate the couch a bit to get in front of them and hope nobody else complains. Next step is get a calibrated microphone like a UMIC-1 and learn how to use REW. You don't need any additional hardware because once the necessary EQ is determined it can be applied in many software players. For example JRiver has a built in parametric equalizer.

As an alternative to room treatments you may be able to acquire woven items to hang on the walls and some nice drapes for the windows. I have one of those benches, by the way.

Thanks. Just a clarification, I sit in the mission chair to listen: in front. The rest.....yeah.

 

[Ron Texas]

Thanks. Just a clarification, I sit in the mission chair to listen: in front. The rest.....yeah.

It's a lovely chair, but too far away from the speakers for the equilateral triangle. I can't really tell you how to set up that room, but I can say it took me over a year in a new place to understand the room I had available both in terms of aesthetics and acoustics.

 

[Krunok]

I have never tried to use room correction for a couple of reasons. First of all, currently I have active monitors at nearfield distance (about 1m) when sitting by the computer, so I don't really see much point. The second is that when I listen to music I sometimes like to move around and not sit "with my head in a vice" (as Paul Mcgown likes to say).

Is room correction relevant to those two situations?

In my case, although I optimised it for a sofa where I usually listen to music, FR actually got better in other points in the room as well, compared to what it was before correction.

 

[digicidal]

I'm with @Ron Texas on this one (re. putting them on opposite sides of the fireplace). But I feel your pain... I've got a similar nightmare in my family room (though it's mostly TV watching and the room correction helps).

I'd probably go with much longer (but cheaper) cables - and just move them onto the corners of the area rug and then listen from your chair opposite. That way you've got a long way for wall reflections, carpet is covering floor bounce... and the couches on both sides are damping other strays. Pain to do every time, but you'd only do that when you were purposefully listening... for simple ambiance they'd be fine backed up against the wall IMO.

To be honest, I'd probably move the whole setup into a room where they could benefit more from corner reinforcement and balance - even if I had to listen in bed all the time. However, you obviously want to listen in that room, and with that layout... so I'd say DSP is pretty much your only viable route. Especially since significant treatments aren't really possible unless they're movable - even if you got decorator panels that didn't look bad in that room, you can't hang them on a window/door. And they would ruin the aesthetic of that beautiful room/house.

 

[Sleach]

https://www.thomann.de/gb/antelope_discrete_4_synergy_core.htm

Not sure if this is the right spot for this question, but could a unit like this be used as a USB DAC for some DSP? At least by applying some parametric EQs?

 

[GrimSurfer]

There are some recognizable bass bumps, but it also a space that rings a bit when you clap.

Listening to music I find the high end a bit harsh. What can be attributed to the JBL horn tweeter and the room is obviously harder to know. We’ve thought about a curtain by the left speaker, but we are very fond of the sun and large view from those glass doors, if not the cold they bring in winter.

Ringing wouldn't surprise me in that room, though it is quite lovely. Lots of flat sheet rock and glass mean lots of potential for ringing.

First, heavy curtains on the windows and sliding glass doors. The floor to ceiling glass is like a sound mirror and the coved window probably isn't much different.

Second, buy a big piece of deeply framed art for the wall opposite the sliding glass doors. Fill the cavity behind the moderately stretched canvas with rigid Fiberglas. It will damp the mid and high frequencies.

Third, move the sound system to the opposite wall. It will at least be firing down the hallway and will face the sofa. Avoid having the speakers face the glass doors... they'll act like a mirror and completely screw the sound as it hits your ears from behind... with an obnoxious time delay.

Fourth, art backed with rigid Fiberglas where your system currently is, along with the heavy curtains will break the MF and HF corner reflection.

Sounds like a lot but the only thing you're moving is the sound system. The rest is purchasing some stuff. Assuming you're married, let the missus/partner loose with whatever pleases her... provided the curtains are heavy and the mounting of the art allows at least 1" rigid glas to fit behind it. If you're wife/partner is into photography, showcase the work.

With the obvious room challenges at least mitigated, run REW or some other room correction sw. Adjust speakers and levels accordingly.

The sound should be made to fit the room, not the other way around unless you're designing a build.

Hope this helps!

 

[watchnerd]

So here is my system in my weekend place. The two attached photos show the system and living area, and then turn back and show where I was taking the photo (standing on the window seat).

As you can see, nothing but reflective surfaces, including an angled, high, hardwood ceiling. And very few options for system placement. I generally sit in that Morris Chair where I get a decent image *over* the couch. Still, left speaker is next to a window.

I’m considering getting a DSP front end to tackle some of the room effects. Looking at MiniDSP and RME. Having never used DSP before, what do forum members recommend?

I’m also extremely fond of the living area as it is, so I’ve been reluctant to look at room treatments. Hopefully you see why.

Eventually those JBL L830s will be replaced with another pair of Harbeths. They make a good, clean image but don’t have the timbral accuracy or image scale of my Harbeths in my NYC apt.

I appreciate any advice you might have to offer.

PS, yes that is fairly expensive audiophile cable I bought in a moment of weakness in 1993. Don’t hurt me. I just keep using it.

Why don't you just sit nearfield?

Not all the problems, but a lot of them, will go away.

 

[ahofer]

Incidentally, I’ve made a speaker change to Revel F228be (bought used). They sound great to me, from all over the room. The bass definitely is different in different places, and there’s much more of it in general with these speakers.

I slide them out when setting in to listen to make more of a triangle. As suggested above, the tweeter and midrange are now elevated further above the couch I’m facing.

Still trying to socialize the idea of having them on either side of the fireplace, but it’s not going well. It also means we have to change our customary evening positions(!!).

At any rate, I’m more convinced now than before that these even dispersion speakers can sound good in a variety of placements.

 

[ahofer]

PPS, and I've run REW and created convolutions for pushed-in and pulled-out positions. The improvement pushed in is huge. Discussed in another thread.