#1681744 - 06/09/05 07:46 PM
HPF in the recording chain
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jbr
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The KSM44, Grace101 and finally the Digi002Rack all have HPF's on them.
With that recording chain, and when required, does it matter which one's used?
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#1681745 - 06/09/05 09:29 PM
Re: HPF in the recording chain
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where02190
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Yup. the further down the chain you HP the further the unwanted information(read acoustic energy) travels before you put the brakes on. If you HP at the mic, the signal out of the mic is what is used throughout. If you HP going into the 002, you then have all this low end energy that's driving the pre that you're gonna essentially toss out, and your resultant input level to the 002 can be significantly lower. HP at the mic, and you will end up driving the mic pre a bit harder, since you lost that LF energy, and get a better S/N ratio and better signal level into the DAW.
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Hope this is helpful. NP Recording Studios Analog approach to digital recording.
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#1681746 - 06/10/05 07:38 AM
Re: HPF in the recording chain
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miroslav
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While Nick has a very good perspective...
…and I agree, that IF you ARE going to use a filter, do it at the beginning. 
But there is another school of thought.
Putting aside those instances when you are recording on a very resonant surface (like a typical wood floor in a house), and you do not want that low-end "foot bumping" to find it's way into the signal...
...why the heck else might you need to use the HPF...???
If the source you are recording is mostly a mid-to-high frequency source...well...there ain't gonna' be much LF energy there to begin with anyway, to push the pre all that much.
BUT…there might be just enough LF there, that it gives that particular source a bit more of its identifiable character...and so…you really might not want to roll that off with the HPF...IMO.
Also...if the source has a bit more LF...and THAT really DOES do a lot to identify its character...then you most certainly would NOT want to roll it off with the HPF...IMO.
I'm not saying that there are NOT any situations where your would use the HPF...sure there are, and in those situations…do like Nick said.
But I'm just suggesting that you should first consider WHY you would even want to use the HPF on any particular source...rather than just have it always turned on with every mic all the time.
Personally...I rarely HPF any source...and I also rarely PAD at the mic.
With a good mic and a good pre...it's not really necessary to do that...unless of course, you have that very first scenario...a resonant floor that allows all kinds of LF noise to travel up the mic stand and into the mic.
But...that is also easily cured with a good shock mount...before you ever reach for the HPF.
However…if your mic and/or pre are easily taxed by stronger signals…well…then you are just fixing something that isn’t working right to begin with.
On a hard surface....nothing is going to resonate it's way up the mic stand...unless maybe someone is using a jackhammer next door! 
My studio is all solid cement flooring...so I can jump up and down next to the mic...and none of those bumps get into the signal.
Another reason why people reach for the HPF...is due to extreme close-mic techniques.
Back those mics off a bit, and let the source breathe some!
Me...I like to use mics and pres as "wide open" as possible...and I hardly ever EQ, and/or compress going in. 
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#1681747 - 06/10/05 09:53 AM
Re: HPF in the recording chain
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jbr
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Great info guys!
Yeah, the resonant floor is the main reason for my thinking to use the HPF. I also thought that if the source has little/none LF, why not use the HPF anyways to keep clear any LF room resonants and to keep the LF open for mixing instruments with LF. I read somewhere for tracking drums, to flip the hpf switch for everything except kick because the kick is where you want the LF to be felt/heard. Does that make sense?
Thanks
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#1681748 - 06/10/05 10:09 AM
Re: HPF in the recording chain
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gaotu
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I'm in the same boat as JBR, I have 3 mics that have rolloffs on them, 2 pre's that do, and then of course there's EQing later. Last night was the first time I've ever used a HP during recording in the chain. And I found it useful then because they guy's guitar cab was putting off some weird low-end rattle that was not good, but cutting the bass on the head changed the tone in an unfavorable way. The HPF on the mic (421) worked for that situation.
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#1681749 - 06/10/05 11:18 AM
Re: HPF in the recording chain
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miroslav
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Originally posted by gaotu:
Last night was the first time I've ever used a HP during recording in the chain. And I found it useful then because they guy's guitar cab was putting off some weird low-end rattle that was not good, but cutting the bass on the head changed the tone in an unfavorable way.
Another thing with "lesser" mics...is that their frequency response may be limited...or their internal electronics easily overpowered...then you HPF and PAD...but again...that's a mic problem.
Also...a source that has little LF to begin with will not emit too much LF for it to reflect/resonate with then room . and then back into the mic.
I would suggest you always give things a close listen before you cut/boost equalization.
And...it's always easier/better to roll off some frequencies when mixing...then to try and add them because you don't have them to begin with.
On my drum kit...M/S overheads and spot on Snare and Kick...I don't HPF or Pad.
In the mix...the 4 kit tracks are nice and chunky...but if I need then to cut through a bit...I just pull back some of the LF...rather than having to add HF.
I like having the chunk there to begin with...'cuz whenever I didn't have it...it always sounded like shit if I tried to add it after the fact.
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miroslav - miroslavmusic.com"Just because it happened to you, it doesn't mean it's important."
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#1681750 - 06/10/05 11:51 AM
Re: HPF in the recording chain
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gaotu
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Yea, I definitely don't HPF my drum mics... haven't yet anyway and I do like the "chunk" that's theret. It's much easier just to roll off or decrease LF after the fact rather than adding (especially since I try to adhere to the rule of thumb that you shouldn't have more the 12 db combined added EQ across an entire mix). Especially since a lot of drummers have those "brighter" higher-tuned toms that need the low end to sound full.
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#1681751 - 06/10/05 01:16 PM
Re: HPF in the recording chain
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Chris Cavell
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I generally hi-pass at the mic if and only if needed.
Whether or not the filter within the mic provides any benefit to a filter at the pre depends entirely upon the mic.
Some mics filter passively at the output, in which case their is no real advantage over a filter at the pre.
Others filter b/w the element and the impedance conversion portion of the circuit. These have the advantage of preventing distortion within the microphone circuitry if the power of the low frequencies is great enough to cause undue distortion (very rare with full range instruments). However, some purists feel filtering at this stage negatively impacts the signal in other ways at it's most critical section of circuitry.
Still other mics (this is extremely rare) employ a method of bandwidth limiting the internal electronics. This is by far the best method, but incredibly expensive to engineer in such a way that implimentation on a broad scale is feasible. This type of filter, by virtue of limiting the bandwidth of the electronics of the mic, improve the linear characteristics of the electronics in addition to solving the issues that lead you to turn on the filter in the first place.
Cheers,
Chris
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#1681752 - 06/10/05 01:54 PM
Re: HPF in the recording chain
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miroslav
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Chris
When you say:
"I generally low pass at the mic if and only if needed."
Do you mean that you always DO use the HPF...or was that a typo...and you ment to say:
"I generally high pass at the mic if and only if needed."
???
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miroslav - miroslavmusic.com"Just because it happened to you, it doesn't mean it's important."
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#1681753 - 06/10/05 02:31 PM
Re: HPF in the recording chain
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Chris Cavell
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You caught it miro...definitely a typo. Meant to say high-pass...i'll go back and fix it.
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#1681755 - 06/12/05 09:46 AM
Re: HPF in the recording chain
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where02190
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Sorry I didn't give a 2 cents worth in my first post.
One should definitely conside they why youa re hping. About the only thing I hp is a hat mic or a vocal in a scenario that I know I will want the hp in on the vocal (a 414 being a good example.) Other than the afore mentioned hat mic (which never gets used anyway) I NEVER HP drums, especially overheads, where I capture the essense of the entire kit.
I take the same approach to eqing when tracking, I don't. I take the time to get the right sound from the instrument, tuning, mic placement and choice, preamp selection, and subscribe to the less is more approach, putting the minimal amount of electronics between source and destination.
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Hope this is helpful. NP Recording Studios Analog approach to digital recording.
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