The disappearing reverb problem

Discussion in 'Mixing & Editing' started by td, Mar 10, 2002.

  1. td

    td Guest

    Hello neighbors,
    It seems of late I've been having a problem accurately gauging the intensity of the reverb in my mixes. I recently set up a new workstation that changes the geometry of my room a bit and have just started the first round of mixes for a new project. Usually I don't use lot's of reverb, but this project is based around the Native American flute and requires full, lush 'verbs on some of the material. OK, the problem is what I'm hearing in my room sounds great ..... full with nice tails, but when I play the mixes elsewhere the verb is over the top & doesn't correlate with my monitoring. I'm using an TC M3000 via SPDIF i/o & a Sony DPS V-77 via analog, so the reverb quality is pretty decent.

    The room is far from optimal ..... it's small and dead - 11 x 14 x 7.5, the freq balance I can judge pretty well, but can't judge the verb accurately to save my life. I'm monitoring on KRK V8's off of a Lucid ADA8824 D/A.

    Anyone ever experience this or have any thoughts??

    Thanks,
    Tony
     
  2. knightfly

    knightfly Active Member

    Joined:
    Jan 18, 2002
    If your 'verb sounds right in a dead room, it would almost have to be over the top in a reasonably reverberant room. When listening to playback in the normal room, you're getting all the reverb you put on "tape", plus whatever the charactaristic of the listening room adds to the mix. This is why mixes aren't usually done in an anechoic chamber. You might try some other "native american" flute CD's in your mix room, paying close attention to how sparse and dry the 'verb sounds, then try to dupe that sound with your own mixes. Or, is there any way to get rid of some of the absorption in your room without causing other problems?

    If those are the exact dimensions, there doesn't seem to be a problem with the Bonello Distribution of your room other than no modes below 40 hZ, so it could be just too much absorption. Have you measured the RT60 of the room? Is there a carpet or drapes that could come out? 12 extra bodies listening while you mix?

    As low as your membership # is, I don't want to carry coals to newcastle - however, I also don't want you to miss out in the event you haven't considered it, so here goes - click on the following link, and then click on the "files area" -

    link removed

    they have some very useful tools near the bottom of the page for calculating room modes, diffusors, RT60, etc. - I have used a couple of them and they work pretty well. They also have a chart of absorptions for common materials. From all these, you should be able to nail down pretty closely what your room needs in order to give you neutral results. If you already know all this, sorry for talking down - if you don't, you're welcome... Steve
     
  3. Two things come to my mind:

    If there's any problem with phase cancellation of your monitoring you'll perceive less reverb effect as you mix. :confused:

    You didn't mention on what or where you've taken your mixes to listen, but make sure a buddy's boom box or stereo system isn't employing those "spatial enhancer" modes, which would definitely over-state a reverb effect. :w:
     
  4. realdynamix

    realdynamix Well-Known Member

    Joined:
    Feb 23, 2001
    I am sure you did this, check your mix in mono. Short delays, like below 20ms, of dry early-echo can cause cancelations of center channel information that is using the verb. Most of these very early pre-verb dry echos are very short, less then 5 ms.
    Just a thought,
    --Rick
     
  5. RandomGuest

    RandomGuest Guest

    Joined:
    Feb 10, 2001
    Use some headphones?

    Then get round to cheering that room up and making it suck out less of the speakers 'life'.

    :)
     
  6. RandomGuest

    RandomGuest Guest

    Joined:
    Feb 10, 2001
    I don't know, J. If I had to pick one area in which headphones are most suspect, it would probably be evaluating reverb. Maybe it's just me.
     
  7. RandomGuest

    RandomGuest Guest

    Joined:
    Feb 10, 2001
    To be honest I rarley ever use them at mixdown, that said I just bought a pair.. so I should try em out today!

    BTW I find the M3000 subtle and 'disapearing' anyway! Kinda hard to hear sometimes.. I suppose thats good right? :)
     
  8. Bob Olhsson

    Bob Olhsson Distinguished Member

    Joined:
    Feb 13, 2001
    Location:
    Nashville TN
    Home Page:
    I've always found I didn't use enough reverb in a dead control room or on headphones.

    Beware that a lot of electronic reverb units simply send out of phase mono reverb to their "stereo" (right...) outputs. Others such as lexicon shift the pitch flat as you add predaly.

    You can use tons of reverb from a real plate or chamber and love it however even tiny amounts of most digital reverbs will suck. I haven't played with the new Sony and Yamaha products yet. Reverb is an area where quality has really gone downhill over the past 30 years.
     
  9. td

    td Guest

    I guess it's just more shitty room traits rearing their ugly heads. I measured the room again - 14'3" x 11'4" x 7'. I have 2 inch foam on about 80% of the ceiling to keep the mid/ high freq reflections from bouncing back to the microphones, the floor is carpeted, the backwall behind the monitors is 2" foam, & I have 2 Auralex T-fusors on each side wall in the middle of the room, plus alot of instruments around the room.

    Really I just need to build a real room at some point, but I'm not there yet ($$). Is it possible to get this room anywhere decent shape acoustically ( afraid I already know the answer :) ) ?? Where to start?

    Knightfly, thanks for the link ....... I wasn't aware of that site and it seems I should be.

    I know everything is wired properly - my speakers are in phase and stereo imaging is nice.

    I'm going to be sending this project to a mastering engineer fairly soon so it'll be interesting to get his take on it.

    Thanks for your help
    Tony
     
  10. Everything you said is so true!

    May I add, I like to check my verbs on small speakers and also in mono. If you hear it clearly there's too much, if muting it almost make no change there ain't enough...

    The little speaker in a Studer B-67 or A-80 is the best for that! :( :confused:

    Good luck! :w:
     
  11. knightfly

    knightfly Active Member

    Joined:
    Jan 18, 2002
    Tony, I just ran your new dimensions on a simple spreadsheet I wrote about 10 years ago (does axial modes only + bar graph) and your room by itself will have several mode coincidences, at 80, 160, 240, 320 - a couple of those could really excite an acoustic guitar, or even a piano. The spreadsheet that's available at studiotips.com doesn't think your room is all that bad as far as Bonello distribution, although the modes I mentioned do show up. According to F. Alton Everest, we should strive for axial modes that don't coincide, are at least 4-5 hZ apart, and not more than about 20 hZ apart. Barring that, hopefully the other two sets of modes will fill in gaps.

    If you don't already have a copy of Everest's Master Handbook of Acoustics, it will be the best money you can spend to help your existing room all you can. Amazon.com sells it for $24.46.

    If possible, try this: walk into your room, clap your hands really sharp (no mics up) and listen to the decay. Then remove all the instruments and try again. Is the carpet fastened down? sounds like you have enough absorption without it.

    I have a similar mode problem with my old room, which in the short term is acquiring a new end wall, shortening it from 35.5 feet to 20 feet. (The other resulting space can be for instrument storage, workbench, duping, etc.)With a width of 11.5 feet and a ceiling height of 8.2 feet, the axial modes get really well spread except for one spot down around 40 hZ, which will be a good place for a bass trap experiment. I'd be interested to know how/what you do for your room - If you like, you can email me at knight001@compuserve.com, or just post back here... Steve
     

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