Problems @ 94, 114, 320, 784Hz

Hello to all, I just found a great (I hope) tool to measure my room acoustics and: I found some problems @ 94, 114, 320, 784Hz. This the studio, but its more empty now ! http://www.johnlsayers.com/phpBB2/files/1_481.jpg I mixed already some songs and these are nearly exactly the frequency it is very, very hard to realize any soundchanges when tuning frequencies with an equalizer during the mix .. Has anyboda tips for me how to get rid of these mega-dips in the frequency spectrum ? Thanks !

liax,

liax1975 wrote:

I mixed already some songs and these are nearly exactly the frequency it is very, very hard to realize any soundchanges when tuning frequencies with an equalizer during the mix ..

I am having trouble understanding this statement. Are you saying it's hard to hear the difference with and without an EQ? Are you hearing problems in your mixes - i.e., are they not translating?

Has anyboda tips for me how to get rid of these mega-dips in the frequency spectrum ?

If your graph is a true representation of the sound at your mix position, you're in pretty good shape. From 20 Hz and up, the response is more or less ±5-6 dB, which is very good. The two dips you see are likely caused by loudspeaker / ear / boundary distances and not modes (they're too high in frequency). Give us your room dimensions and we can get a better idea. Otherwise, I'm willing to bet that if you move the microphone a matter of inches, the dips will move / disappear. In which case, you might try to figure out which surfaces are the offending ones and treat them with some 2"-4" panels, which should be plenty to address reflections in the 300-800 Hz range. Besides that, I would venture to guess that actually hearing these dips would only be possible if someone hit the notes (roughly a quarter-tone flat E4 and almost exactly G5 for 320 and 784 Hz, respectively) perfectly. Otherwise, the bandwidth of the ear should compensate well at these frequencies. Again, give us an idea of the dimensions of the room, loudspeaker and mix position locations, and a little bit better description of the problem(s) you're having and we'll be able to help you more. :)

liax1975 wrote:

Has anyboda tips for me how to get rid of these mega-dips in the frequency spectrum ?

Yes, you need bass traps. The more you have, the closer you'll get to a flat response. It's that simple. --Ethan

Ethan Winer wrote:

liax1975 wrote:

Has anyboda tips for me how to get rid of these mega-dips in the frequency spectrum ?

Yes, you need bass traps. The more you have, the closer you'll get to a flat response. It's that simple. --Ethan

Unless you already have boatloads of them that you haven't told us about. :)

It could be even simpler - maybe his speakers are out of phase.

John, Could be. Check out the pics under the "Do It Yourself" section on his "Gallerie" page: http://www.liax.de/A_03-Pics.asp Looks to me like he's already got a ton of bass control - slat absorbers, etc. I think the shiny façade on the front wall might be fabric over fuzz. Liax, can you confirm? If so, then the 300-800 Hz stuff is anomalous, I'm betting. Best I can tell, it should be a good-sounding room...

I see a couple of problems. First is the soffit mount construction. There is a part missing below the speaker. The idea is to continue the baffle to 1ft above floor level. I do it by adding a plywood/mdf to the back of the front studs below the speaker and add insulation between the studs. This keeps the baffle going, adds a port at the floor/wall join back into the cavity under the speaker which is a bass trap. The insulation stops reflections off the back of the console coming back to bite you. Second - the gap between the slots is too great, they are tuned too high. they are ineffective as slots and because the angle isn't great they don't really create a RFZ. It's a pity you didn't fil the rear wall hanger sections with bigger hangers - you had the space. Here's Warren's front showing what I mean. cheers john

Thanks for the answers. 1.) "..........First is the soffit mount construction. There is a part missing below the speaker. .." Damn .. Hmm .. I have only small space for hangers below the speakers, so i placed some small ones below the speakers .. Would it also be possible now to build two "boxes" to put them in front of the suffit mount on the floor (or 1 feet above) or would it be better to place a MDF plank there (remember the small hangers, don´t know if they catch really bassfrequencies ?) ? If a box, how should it look like ? 2.) "..........Second - the gap between the slots is too great ... " This is something I like to change soon, maybe with MDF ? If I understood right, it should look like this : http://www.johnlsayers.com/Studio/Image ... ooth_4.jpg ?! 3.) "...........It's a pity you didn't fil the rear wall hanger sections with bigger hangers ......" The section behind me is not very high ... But I can still add some hangers !! Should I put the complete rear wall full with hangers ? or only some more in the corners ? Again, thanks for the answers. Hope to get the room a little bit more perfect then i am satisfied !!

You've got it ;) The slots you posted are Bruce's - he used a sheet of veneered mdf or ply (I'm not sure which) which he then cut down into strips and mounted them randomly - it's a nice look. cheers john

Cool, will try this week. Is anywhere a description or explanation concerning bass hangers, width, height, absorption and so on ? Can´t find it here .. ?!?

I found it .. http://www.saecollege.de/reference_material/index.html

Just one thing concerning these hangers. It sais, they should be 12 inches width and (for bass hangers) approx 70 inches heigth .. but I have no 70 inches space in the height behind me .. may it be good to give them more width, so that i got the same square feets as 12 x 70 ?

lovecow wrote:

Unless you already have boatloads of them that you haven't told us about. :)

As a matter of fact I do have boatloads of bass traps. :) --Ethan

Your living room looks like a warehouse full of them ;-) http://www.realtraps.com/cust_ht5.jpg

Ethan Winer wrote:

lovecow wrote:

Unless you already have boatloads of them that you haven't told us about. :)

As a matter of fact I do have boatloads of bass traps. :) --Ethan

I was addressing liax with that post. Should have been obvious...???

lovecow wrote:

I was addressing liax with that post. Should have been obvious...???

Yes, I knew that. But if the shoe fits, I wear it. I was just funnin' ya Jeff. --Ethan

liax1975 wrote:

Your living room looks like a warehouse full of them ;-)

LOL, but who cares what it looks like? It's the best sounding room you'll likely ever hear outside of a big budget studio like John Sayers designs. --Ethan