John Sayers' Recording Studio Design Forum Archive

But in the meantime, I was curious how the new speaker setup would perform so I did a few quick tests and here's the MDAT from that... It completely took away that huge 350hz problem...although it did seem to add a few dips further up the scale, but nothing HUGE like that 350hz deal that was going on. I listened to some tracks while placing myself at 55" to the ear from the front wall...and the first thing I noticed was, in the new orientation, the stereo soundfield seemed different, much wider. Sounds that were panned hard seemed almost as if they were coming at me directly from the side...quite amazing actually. Also, there was a noticeable bump in the low end as well...it sounded a bit fuller and a bit more balanced than before I think.

Yup! That's pretty much what I expected!

Having the correct geometry makes a big difference. The new dips at the higher frequency are also what I wanted to see, since they are far less important than dips lower in the low end, and much lower magnitude. With the smoother response, we have now also clearly exposed the front wall effect (baffle step response): there's an obvious rise now clearly visible in the low end, starting at about 350 Hz. That's normal, and is due to having the speakers close to the front wall, which is now automatically compensating for the inherent power imbalance that comes from enclosing a speaker in a small box. The internal circuitry of the speaker is already trying to compensate for that, but the front wall does a much better job, so you'll need to use the bass roll-off controls to correct that. Basically, that will remove some of the compensation that is being applied by the cross-over circuitry, but that you no longer need. Adjust the "LF Contour" controls on your speakers to about -4 dB and see how it looks then. You'll need to re-adjust once you get the sub in, but for know do a quick test with just the speaker controls.

One more thing: Adjust the HF contour down a bit as well: your very high end is just a fraction too hyped right now, so try puling that down to -1 dB, then test with REW (and with your ears!)

in the new orientation, the stereo soundfield seemed different, much wider. Sounds that were panned hard seemed almost as if they were coming at me directly from the side...quite amazing actually

Yup! You now have a proper "stereo stage"! It sounds like it might be a bit too wide, but we can fiddle with that after you get the sub in and get the rest of your issues sorted out.

Also, there was a noticeable bump in the low end as well...it sounded a bit fuller and a bit more balanced than before I think.

Yup. That's the baffle step response issue I mentioned above. It was there before, partly, but was messed up and masked by the other artifacts. Now you can see it (and hear it), because we have cleaned up those artifacts with the changes in geometry.

In other words, before, your speakers were lying to you: now they are telling the truth. Or rather, the way the speakers were set up in the room was causing a combination of issue that "colored" the sound, and distorted the spectrum. But now those artifacts are greatly reduced, and you are hearing things much closer to the way you should be hearing them.

You should also now be haring the bass more immersive, tighter, and cleaner, and you should be hearing the "phantom center" speaker on things that are panned spot on the middle. If you close your eyes and listen carefully, it should sound like there is another speaker directly in front of you, in the middle, and some of the sounds are coming from that: probably the snare, vocals, and some instruments. If you are getting that, tight bass, and a clean stereo sound stage, then you probably have things about as well set up as you can expect, with that desk in the room, and for that size of room. You might be able to tweak things a bit better still, by moving the speakers around just slightly then listening / testing again, but my guess is you probably wont get a huge difference from that: we already got you the huge difference by correcting the geometry!

So set up the sub as I described above, get it adjusted to play well with the mains, and do another test so we can get back to the remaining big question, about the rear wall treatment, and getting your very low end tamed! I'm betting that the modal issue at 50 Hz, is going to blossom into a real beauty, once you get the sub going... and there will also be some other monsters hiding down there, that we'll need to tame...

Thanks again for all the help!

That's what we are here for!


- Stuart -

Hi Stuart! Sorry it's been a few days here, had some things come up...but I finally got the sub in and took a measurement but had some questions. First, here's the MDAT file...

https://www.dropbox.com/s/lrdm29psn4l8e ... .mdat?dl=0


Now, I had several options on my SUB6 as to crossover points and what not. I did what you said and tried the phase both normal and inverted and you were right, the "normal" on mine had a huge dip in it. So I put it to inverted and the big dip went away in favor of some much smaller bumps! I tried playing with the phase knob, to try different phases, but "0" seemed about the best as you thought.

Another feature of the SUB6 is that ONLY when the sub is active, it can crossover the mains at either 75 or 100hz. I tried this both ways and no matter what I tried this seemed to introduce a very large dip at around 100hz, so I left it on "defeat" which allows the mains to play full range with or without the sub. However, I wonder if I was doing something wrong there...if that should be crossed over while the sub is being used?

I set the low pass for the sub to just under 100hz, if I had to guess I'd say it was about 95hz or so...and I set the level to about -16.

Looking at the MDAT file, and comparing it with the last BOTH mains file, it actually looked pretty good to me...in terms of relative smoothness in the low end. When listening to different tracks I found some interesting things. Everything sounded MUCH better to me. The low end sounded fuller without being overbearing in the listening position. It was interesting too that it didn't seem to add much volume to the back of the room where alot of the bass was collecting before about 2ft. off the rear wall. This surprised me ALOT. I thought for sure that the sub would make that area much worse...but it really didn't. I even took some measurements with the sub on and off back there with my handheld SPL meter. The difference with the sub on/off was maybe about 5db on the meter. However, the sub made a big difference in the rest of the room...for example the center of the room wasn't as void of bass as before, and the listening position was more forgiving on the bass as well (less change over movement). Pretty much every track I listened to gained "something" with the sub on. It's like parts of the music were missing before...maybe missing isn't the right word...everything just felt fuller, without making things muddy or real bass heavy. I know from the graph it's still too loud, but I wanted to send this first graph to you so you could look at it and see if I should make any changes to the crossover points or anything before I move on?

What are your thoughts on this?

Thanks!!

Brian

Hello Stuart! Didn't want to be pushed to the next page...check out my post above when you get a chance!

First, here's the MDAT file...

That looks quite reasonable, actually.

Another feature of the SUB6 is that ONLY when the sub is active, it can crossover the mains at either 75 or 100hz. I tried this both ways and no matter what I tried this seemed to introduce a very large dip at around 100hz,

Did you also try that in conjunction with the "phase" setting? There might be a combination of settings that works.

Also, don't forget to try moving the speaker around a bit: often you can find better response like that. If you don't have much space to move it left-right-forward-backward, then try moving it up to: stack books under it, for example. And play with all of the controls in each position, as well.

so I left it on "defeat" which allows the mains to play full range with or without the sub. However, I wonder if I was doing something wrong there...if that should be crossed over while the sub is being used?

Normally it should be crossed over, so that you don't have three sound sources all trying to reproduce the same frequencies, but if you are getting good response like that, then you should be OK.

I set the low pass for the sub to just under 100hz, if I had to guess I'd say it was about 95hz or so...and I set the level to about -16.

That sounds about right. I often see recommendations to shoot for 80 Hz, but I do often find that 90-something gives better results in small rooms.

Looking at the MDAT file, and comparing it with the last BOTH mains file, it actually looked pretty good to me...in terms of relative smoothness in the low end. When listening to different tracks I found some interesting things. Everything sounded MUCH better to me. The low end sounded fuller without being overbearing in the listening position.

Yep! Then you have achieved the Holy Grail of studio tuning! That's the way it is supposed to be: clear, tight bass without overwhelming.

It was interesting too that it didn't seem to add much volume to the back of the room where alot of the bass was collecting before about 2ft. off the rear wall. This surprised me ALOT.

Right. Because the sub isn't increasing the volume for any specific frequency: it is just adding more frequencies to the available range. And since most music doesn't have several bass guitars going at once, there's normally only a very few frequencies playing down there.

It's like parts of the music were missing before...maybe missing isn't the right word...everything just felt fuller, without making things muddy or real bass heavy.

Congratulations! It looks like you have found a good combination of sub positions and settings, and also treatment. There's still some room for improvement, but what you have is pretty good.

I know from the graph it's still too loud, but I wanted to send this first graph to you so you could look at it and see if I should make any changes to the crossover points or anything before I move on?

I would bring your sub volume down by maybe 3 dB, and see how that looks/sounds. Also, if your mains have the option to roll-off the highs, try bringing that down by maybe 2 dB.

But overall, it's looking good.

- Stuart -