Hiss from live concert halls

Posted: Fri Mar 09, 2007 7:49 pm

I'm wondering if there is any way to eliminate the high-freq hiss that is picked up when recording in live concert halls. There may be no way considering my set-up: 2 dynamic cardiod mics placed X stereo running into a Boss Br-864 (portable digital 8track recorder). I currently use the "hiss reduction" function in Adobe Audition to eliminate most of it... this function generally works well, but it does reduce some of the quality of the original wav file. I record live recitals at my school as a service to the students and myself, and this is the best I can do so far... under these circumstances, is there any suggestions to help me reduce the amount of ambient room noise (hiss) picked up during recording?

Thank you.

Posted: Fri Mar 09, 2007 9:54 pm

The hiss is likely due to the high gain you are having to apply to those dynamic mics and the probably low quality of the amplification circuit, not due to ambient noise from the room. The only solution I see is getting yourself a pair of condenser mics.

Posted: Fri Mar 09, 2007 11:59 pm

... or by trying a very clean, low noise, high gain mic amp built for dynamic and ribbon mics, ie the AEA TRP.

Posted: Sat Mar 10, 2007 3:49 am

Quote:

is there any suggestions to help me reduce the amount of ambient room noise (hiss)

ambient room noise and hiss are usually two different things. If you can hear a hiss in the room itself then then try and find the source of the hiss and see if you can do anything to reduce it. If you cannot control the noise at the venue, you don't have any option other than resorting to noise reduction in post production, which, as you correctly observed, takes away much more than just noise. If you find that the "hiss" is not there in the hall itself, but has somehow found its way into your recording, then i guess you have your gear to blame Smile

i think we believe here that technique is far more important than gear, but in your case, sadly, i think the bottleneck is in the gear itself.

how are you using "2 dynamic cardiod mics placed X stereo" with a br-864 which has only one microphone input? Presumably you are using the guitar input (which has different impedance and gain specs and is bound to sound different from the mic input), for the second mic?

the zoom h4 is the cheapest thing i can think of that might serve your purpose better than your current gear, tho' it certainly is not going to be a quiet as something a little more upmarket... If you have more than $500 to put into this or you can hire/borrow something better, just ask, and there'll be a few suggestions here...

respect,

Posted: Sat Mar 10, 2007 8:19 am

Hmm. I think rfreez is right on the money with a bit of gear upgrade might be the best and perhaps only way forward. Only problem is that it is addictive, once you have tried some really good gear you will find it very difficult to go back.

As for the Zoom, I am in no way certain. There has been a number of reports on rather mediocre performance on that unit when it comes to hiss. Take this as second hand knowledge, and if you plan to buy, do a thorough test yourself.

Personally I am at the stage that I am happy with what I have, a Sound Devices 722 plus various mics depending on occasion, Sennheiser MKH30+MKH40 or Schoeps MSTC64 beeing current top choices. Told you though, it is addictive.

Gunnar

Posted: Sat Mar 10, 2007 2:47 pm

Thanks for all the comments... there's a lot I've got to learn still!

rFreez: I agree... I'm very limited in my resources. I do use the Guitar input with a XLR->1/4 cable along with the mic input on the BR864... over time and lots of practice I've managed to balance the 2 inputs so they are within 1 decibel of each other. I have 2 condenser mics, however they are very different from each other, so I don't use them together. My 2 dynamics are Peavey diamond series (PVM 22) so they match good. Since I'm still a student, affording something other then what I have probably won't work... however, being on a budget, perhaps I can still upgrade at least my transducers (dynamic -> condenser)?

Thanks.

PS-hopefully my vocabulary is correct... I'm still new at learning most of this stuff.

Posted: Sat Mar 10, 2007 7:39 pm

Don't try to eliminate it with software. REDUCE it enough to eliminate the distraction, but not so much that it impacts the source material.

I prefer Noise Reduction in Audition over the Hiss Reduction. Lots of control with the NR. It will take a while to learn the tricks, but it's worth taking the time to figure it out.

Posted: Mon Mar 12, 2007 8:37 am

zemlin wrote:

Don't try to eliminate it with software. REDUCE it enough to eliminate the distraction, but not so much that it impacts the source material.

I prefer Noise Reduction in Audition over the Hiss Reduction. Lots of control with the NR. It will take a while to learn the tricks, but it's worth taking the time to figure it out.

I agree.

In fact, in the past 8 years, I have used noise reduction maybe 2 times. And I've worked in some VERY noisy (crappy) halls. As Karl states - reduce the distraction, don't try to eliminate the noise.

Noise reduction, in general, sounds very artificial and the artifacts that it imparts on the signal are simply unacceptable.

The hiss problem you're speaking of is definitely an equipment issue.

The differing input impedences (even with the converter) poses a problem as a different sound (regardless of gain) is getting recorded on each channel.

I would suggest getting some kind of inexpensive solid-state recorder with 2 microphone inputs and using your dynamics. Yes, you will have some hiss still as the preamps will have to be cranked and inexpensive pres are generally noisy pres.

Eventually, like others have indicated here, you will want to upgrade to better mics, better pres, better medium, better converters, better..........

Well, welcome to a very addictive passion!

Posted: Wed Mar 14, 2007 3:17 am

zemlin wrote:

Don't try to eliminate it with software. REDUCE it enough to eliminate the distraction, but not so much that it impacts the source material.

This is a very important point, well put Zemlin. I find that many people (especially novices) get so focused on removing the problem that they forget to check what's left of the actual signal. Throwing out the baby with the bathwater!

Also, Ardroth: I would suggest checking whether or not the average listener actually notices your existing hiss problem. Here's why...

I have often got totally hung up about some hiss or whine or similar that I have no control over, only to find that I'm the only person who notices it. Given the opportunity I'll do whatever I can to prevent it, of course, but these days I'm better at judging what the average listener will pick and what they won't. Being able to dismiss those unsolvable problems with the understanding that "the average listener will never notice" makes the job of recording a live concert much more satisfying. Smile

I don't mean that to sound like a cop-out, but if I got hung up over every technical imperfection that was beyond my control (or budget) I would've given up recording many years ago, out of sheer dissatisfaction.

An equipment upgrade would definitely be worthwhile for you, that is beyond a doubt. In the meantime, don't let a bit of hiss stop you from honing your skills and enjoying the thrill of capturing and reproducing a live event. Most people buy recordings for the music, not the specs.

Posted: Wed Mar 14, 2007 8:34 am

Very interesting posts all around. I was just thinking about this the other day (noise/hiss), and it occured to me that it's gotten so little attention anymore, due to great mics, pre's, lots of gain, etc.

I was doing a live remote broadcast, (with next to NO EQ on any of my important mics, except for a little low-end rolloff) and it hit me at the time that I no longer had to worry about noise in the signal chain, only noise at the source: Air handlers, heat/steam vents, people breathing, etc. What a difference the last 25 years has made, technology-wise.

I too will use a de-hisser only sparingly nowadays, and it's often only when I'm working with an old archive recording, usually analog. Otherwise, I'm finding I can actually REDUCE some of the top end on recordings that have been multi-mic'd with lots and lots of wonderful, bright, crisp and shiny condensers.

of course, getting down with a few warm ribbon mics wakes you up to that quite quickly! Wink

Posted: Wed Mar 14, 2007 8:42 am

JoeH wrote:

of course, getting down with a few warm ribbon mics wakes you up to that quite quickly! Wink

I don't know...I get some hiss on ribbons when the source isn't that "loud" and I have to crank the gain...

Posted: Wed Mar 14, 2007 9:02 am

I put that in a weird context....I mean that a lot Condensers used together can add up to a lot of top end, which contrasted to ribbon mics, can certainly be a BIG difference, once you've heard the diff for yourself.

But I agree, it's easy enough to get hiss out of a ribbon mic, even with a good preamp. The R84 is wonderful, but it's easy to overdo it and get some unexpected hissssss..... Sorry for the awkward context.

Posted: Tue Mar 27, 2007 12:02 pm

Ardroth,

I checked a few specs and the PVM 22 has a sensitivity of c. 4mv/Pa, i.e. c. -48dB re 1V/Pa. A typical condenser mic will have a sensitivity of 12-16mV/Pa, i.e. -38.5 to -36dB so that upgrade should improve your signal to noise ratio by 10 to 12 dB.

Beware hower that real consdenser mics tend to need phantom power (or some other kind of external supply) and you won't get that from a guitar input. There is a kind of condenser called an eletret which doesn't require phantom power but I wouldn't bet on that being any more sensitive than the dynamics you already have.

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