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Gear / Technical Help => Ask The Tapers => Topic started by: Do.com on February 23, 2005, 02:25:08 PM
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I have a set of DPA 4061s wired to a SP Battery Box. I plan to try them out tonight for a loud rock show on the Stacks, so pretty loud. What shuodl I set the rolloff to? My choices are:
16
69
95
107
160
195
888
Shuold also specify that I'm going line-in on a Sharp MD. Yeah yeah I know, but my NJB3 is on the way. Thanks in advance experts!
Clint
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I use no rolloff, personally
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i use 95 hz when i tape dmb from about the first 10 rows running at853s > battery box > ad-20 > d8
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95 should be fine, you can always add a but more lowend, but taing it out can be a problem. Better safe than sorry.
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95 should be fine, you can always add a but more lowend, but taing it out can be a problem. Better safe than sorry.
really? I've always thought the opposite. ???
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DPA's 4061 are omni, that means no proximity effect..I wouldn't roll off........
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95 should be fine, you can always add a but more lowend, but taing it out can be a problem. Better safe than sorry.
really? I've always thought the opposite. ???
i agree with you pfife. ime it's always better to REMOVE something than to ADD.
marc
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the only thing I've ever worried about w/ not using roll-off is that I might overload the mics, and ruin the recording. If it does overdrive the mics, I can run a filter or something in post (if needed) - that way, I can compare changes and determine which is best, as well.
That being said, I've never used rolloff, and never felt that I should have. That's just me tho.
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as someone whos used the 4061's for many shows taking 95hz off at the stack is no problem belive me those things suck in every little bit of bass in the room for something like a thrash metal band ive gone a shigh as 195hz at the stack, but 95hz is the number you will use at most hard rock shows within 30' of stacks.
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The MD line-in used by this taper has an impedance of 20 kOhms. So the frequencies listed are
off by a factor 1/2. That means the "195" setting will result in a -3 dB point at 98 Hz - a suitable filter for the 4061s.
One argument in favor of removing excess bass right at the mics, is to avoid having the bass eat up major portions of your available dynamic range. If you keep the excess bass during the recording and remove it during post production, you'll end up with a signal with (much?) less dynamic range.
FWIW - JMTOT
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the only thing I've ever worried about w/ not using roll-off is that I might overload the mics, and ruin the recording. If it does overdrive the mics, I can run a filter or something in post (if needed) - that way, I can compare changes and determine which is best, as well.
That being said, I've never used rolloff, and never felt that I should have. That's just me tho.
The bass cuts we're talking about here are not really helping the mics. The bass cuts are located on the output of the batteryboxes. I.e the full bass hits the mics and they have to convert the energy to electrical signals. But with them bass cuts engaged, the mics are asked to deliver less current into the recorder -- meaning you do get a small benefit from a lighter load.
Jon
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so a rolloff is not like basically taking a frequency and lowering it, or taking a range of frequencies and lowering it?
What's the difference between running a 95hz rolloff, and taking the same recording and running an EQ over it lowering the 95hz the same volume as the roll-off would?
+t for being a fountain of information of things I don't understand at all...
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Jon is incredible.
:) +t
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so a rolloff is not like basically taking a frequency and lowering it, or taking a range of frequencies and lowering it?
What's the difference between running a 95hz rolloff, and taking the same recording and running an EQ over it lowering the 95hz the same volume as the roll-off would?
+t for being a fountain of information of things I don't understand at all...
Not sure were you are coming from in the first sentences above. In this context I view the terms "basscut", "bass rolloff" & "high pass" as the same thing. Batteryboxes typically implement the filter using a single capacitor on the signal output port. The capacitor prevents bass energy from escaping the batterybox while at the same time it passes higher frequencies. The transition from block to pass is gradual as in 6 dB per octave. So the highpass affects an entire band of frequencies: the band from 0 Hz and up to the filter knee (where the signal by def is only 3 dB down).
Activating the filter does not lighten the job (much) for the mics sitting at the front of the battery box.
Now, say the PA stack can't deliver truly deep bass. So the sound guys boost the 70 to 90 Hz range by 12 dB to give the impression of a solid low end. You're at the rear of the hall with omni mics and get the full boundary effect (ref PZM mics) from floor and sidewall. So your 4061 sees the 70 to 90 Hz band 24 dB (12 from boost + 12 from boundaries) stronger than the "natural" flat level (where the midrange and highs live).
You run without filter. You glance at your levels at think "wow - hot levels tonight". You turn the record dial down to accomodate the 24 dB bass hump without "over" lights coming on. What you might not keep in mind is that the mids and highs peak at -24 dB.
So you come home. You EQ out the excess 24 dB of bass and are left with a properly balanced recording with peaks at - 24 dB FS. I.e you are left with a recording equal to if you ran the batterybox with it's bass filter turned on AND the record levels such that peaks were at -24 dB FS. If this was a 16 bit system you would be making a 12 (11?) bit recording. You will probably "normalize" this to get the peaks at 0 dB FS but is't still and forever after, a 12 bits recording.
This was an example. Possibly exaggerated to show what the differences are and some of their consequences.
Questions to ponder are
1) would it be equally bad if it was the highs that were boosted 24 dB?
2) what did they do wrt to boost (EQ) in the analog world when recording onto LPs & cassettes.
Jon
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Has anyone cracked open one of the SP boxes and checked cap values to confirm that all their numbers are based on 10k input impedance? Just curious.
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Thanks Brad, I am starting to feel like a moron here... But finally someone agrees with me. And believe me, I have had some bass distortion problems in the past, and if someone here really knows a nice CLEAN way to remove it, then please let me know. I consider myself pretty knowledgeable in the ways of mastering. It is super damned easy to bring bass up to listenable levels, but it is very hard to remove BAD bass without fucking u pthe rest of the recording... IMHO...
as someone whos used the 4061's for many shows taking 95hz off at the stack is no problem belive me those things suck in every little bit of bass in the room for something like a thrash metal band ive gone a shigh as 195hz at the stack, but 95hz is the number you will use at most hard rock shows within 30' of stacks.
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Has anyone cracked open one of the SP boxes and checked cap values to confirm that all their numbers are based on 10k input impedance? Just curious.
Yes :-). Only one sample though.