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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: Nick Graham on April 07, 2005, 03:38:20 PM

Title: Simple, silly M248 Question...
Post by: Nick Graham on April 07, 2005, 03:38:20 PM
Okay...I know this is total n00b territory, but for some reason I'm having a brain freeze.

What would be the necessary factors for using the HPF (high pass filter) and LPF (low pass filter), i.e. boomy room = LPF? Bright PA and room = HPF? Or is it the other way around?

Title: Re: Simple, silly M248 Question...
Post by: Brian on April 07, 2005, 03:39:21 PM
other way around

high pass = low cut

low pass = high cut
Title: Re: Simple, silly M248 Question...
Post by: mhibbs on April 08, 2005, 03:48:56 PM
Actually, I've always understood it to be this way...

HF+ = On is actually a HIGH BOOST circuit designed to bring the highs up when you are further away from the source (to compensate for HF loss)

LF- = On is a bass rolloff.


Title: Re: Simple, silly M248 Question...
Post by: goose on April 08, 2005, 03:50:51 PM
Actually, I've always understood it to be this way...

HF+ = On is actually a HIGH BOOST circuit designed to bring the highs up when you are further away from the source (to compensate for HF loss)

LF- = On is a bass rolloff.

me too - and they work quite well
Title: Re: Simple, silly M248 Question...
Post by: Tim on April 08, 2005, 03:54:19 PM
mitch is correct
Title: Re: Simple, silly M248 Question...
Post by: Nick Graham on April 08, 2005, 04:24:53 PM
Ahhh....so I was correct.

Imagine that, first time for everything....
Title: Re: Simple, silly M248 Question...
Post by: mhibbs on April 11, 2005, 11:08:44 AM
Not exactly right Nick. 

Boomy room...yes, turn LF- on.

Bright room....don't turn HF+ on.  It's a boost not a cut, so it will actually make the tape brighter.  HF+ is good when you are further away from the source, or really in any situation where you want to bring the highs up some.  I use the HF+ in clubs a lot.

Mitch
Title: Re: Simple, silly M248 Question...
Post by: Brian on April 11, 2005, 11:22:56 PM
well that makes sense because a microphone preamp with a HF cut makes no sense ;)
Title: Re: Simple, silly M248 Question...
Post by: mhibbs on April 12, 2005, 05:02:33 PM
well that makes sense because a microphone preamp with a HF cut makes no sense ;)

Yeah exactly....what the hell would you use it for?  Tape screaming children?
Title: Re: Simple, silly M248 Question...
Post by: Jammin72 on April 15, 2005, 03:54:21 PM
You might use it for recording a show where the engineer has everything so freakin' bright, distorted, and loud that your ears are about to bleed.  You'd be suprised what dropping everything above 15K can accomplish in a room!
Title: Re: Simple, silly M248 Question...
Post by: Professor chaos on May 01, 2005, 08:33:52 PM
which bass roll off is better the one in the mics or the one in the m248?
Title: Re: Simple, silly M248 Question...
Post by: fsulloway on May 02, 2005, 03:17:05 PM
other way around

high pass = low cut



I believe this is correct for a V3 however.
Title: Re: Simple, silly M248 Question...
Post by: Brian on May 02, 2005, 04:14:04 PM
other way around

high pass = low cut



I believe this is correct for a V3 however.

i misunderstood the original post and it was pointed out to me later in this thread.

high pass = low cut   everywhere in the audio field.
Title: Re: Simple, silly M248 Question...
Post by: Tim on May 02, 2005, 06:04:09 PM
which bass roll off is better the one in the mics or the one in the m248?

try em both and see

do they have the same rolloff point and slope?
Title: Re: Simple, silly M248 Question...
Post by: heath on May 03, 2005, 07:50:05 AM
which bass roll off is better the one in the mics or the one in the m248?

try em both and see

do they have the same rolloff point and slope?


it also depends on the what microphone we are talking about...

the easiest way to find out is to listen to them both, as Tim already mentioned.
Title: Re: Simple, silly M248 Question...
Post by: Todd R on May 03, 2005, 10:33:17 AM
it also depends on the what microphone we are talking about...

the easiest way to find out is to listen to them both, as Tim already mentioned.

I don't know, to me, this is the better, but more involved way.  To make accurate judgements, I'd want to listen to at least a couple of different environments (separate shows) using both the mic rolloff and the preamp rolloff.  So you'd probably turn at least a couple of your show recordings into experiments.  Better way of finding out exactly what you like, but not as easy as looking up some specs.

In general, I'd say for our purposes, you want a rolloff point somewhere in the 50-100Hz range.  Maybe as much as 125hz, but if you get up into the 200+hz range, it is going to be too severe.  As to rolloff slope, -6db per octave is best.  This might well lead you to use the preamp since mics often have rolloff slopes of -12db per octave or even -18db per octave.  I don't know about the m248, but I find it unlikely that Doug would have designed taping gear with such severe rolloff slopes.
Title: Re: Simple, silly M248 Question...
Post by: Tim on May 03, 2005, 11:40:37 AM
yep, the rolloff on the u89s sounded great... the rolloff on the 391's is pretty wretched sounding. it all depends on the mic...