Reducing hiss from mic recordings

[unseenreal]

Hi guys, great forum! I've had a look around the forum and found some very good stuff regards md recording but I still have a question someone might be able to help with...

I have just bought a Sony NHF800 Hi-MD recorder and an Audio Technica ATR25 stereo mic. I've spent a few hours today trying things out but seem to have a problem with hiss. I was previously using a MZ-R700 with an inexpensive direct plug in mono mic with reasonable results at least for capturing song ideas. I was hoping that the combination of PCM recording and a better (albeit still budget) mic would give m a big improvement in quality. However, although I have significantly more clarity from the recordings, I can't seem to get a decent level without introducing a lot of hiss.

In AGC mode the hiss is quite pronounced but the recording level is OK. In Manual mode, there is less hiss but it's still present and the recording level (when played back) is low. I've tried changing the mic sensitivity from high to low but that just reduces the overall level.

I've read on this forum that it may be necessary to use an external preamp and record from line-in to get rid of hiss or could it be that I need to spend a lot more on my mic or get a mic with a much higher output? BTW, I tried a new battery in the mic in case it was low, no difference. I bought the ATR25 to get an idea of what was possible before spending £200+ on a pro stereo mic setup (e.g. Rode NT4 or AT 822/825) or a matched pair (e.g. Rode NT5, ES1a). I'm quite willing to do this but want to be sure that I will get good results.

For me the beauty of MD is the simplicity of recording in comparison with say a DAW or PC. All I want to do is get reasonably good recordings of my acoustic guitar and vocals and other small acoustic groups. I don't particularly want to have to carry around loads of gear to get the results I want. Any thoughts or advice gratefully received.

UPDATE: Before posting this I thought I'd better double-check my facts so did a couple more recordings with different settings. The best recording I have got is with MIC Sens Low and AGC on. The result was *very* quiet (I plugged the MD into my stereo with headphones and at full volume the sound level was OK) but significantly the sound was quite natural (taking account of the quality level of the mic) and the hiss level nearly acceptable. I guess I wasn't hitting any AGC thresholds as it was finger picked acoustic guitar and fairly quiet vocals. The mic was about 1m away from me on a table top with small table top stand. If anyone's interested, I could do post some side by side recordings of different settings, but then you'd have to listen to my singing!!!

[A440]

These are very odd results. You should indeed get improved quality. And you shouldn't be getting a low level with the mic plugged in to mic-in unless you have it very far away from you.

First question: are you plugging into the red Mic-in jack, and not the white Line-in jack? Are you getting "Microphone Recording" on the display?

The ATR25 mic has a sensitivity of -50dB, which is less than the one I usually use, the Sound Professionals BMC-2. It is also directional, so it needs to be pointed right at you. Both of those factors could lead to quieter recordings, I suppose. And the hiss you're getting is probably the AGC boosting the level a lot to get it up to audibility because it's getting a quiet signal. Recording music, it's usually better to use Manual volume to stop the AGC from making audible changes during the recording.

But I'm guessing something is malfunctioning. Could be the mic, could be the unit. I mean, here's someone who used the ATR25 to record lighting a fire.

http://freesound.iua.upf.edu/samplesViewSingle.php?id=12809

There's also an ATR25 sample (recorded into a video camera) from this page, a link originally posted here by King Ghidora

http://www.pana3ccduser.com/showthread.php?t=4667

Try another mic, even your mono mic, into the mic jack with the mic seting on High Sensitivity. It should sound more or less as it did on your R700 with similar settings. If it doesn't, something may be wrong with the mic jack on that unit. Or if you're getting a good level with the mono mic, then it's the ATR25.

Edited October 29, 2006 by A440

[unseenreal]

Thanks A440, I'll try out your suggestions and post back my results (if I can find some time today). I'm definately using the mic input BTW.

[King Ghidora]

Is it possible you are picking up interference from something? All mics are not created equal when it comes to picking up interference from things like flourescent lights and various electromagnetic fields. You might want to try a sample recording outside and away from anything electric just to rule out electrical interference. The differences in cables makes a big difference in how much interference a mic might pick up. I'd want to rule this out first if I was having a problem.

Next I would check to make sure your plug was fitting properly into the MD mic jack. It could be a manufacturing defect causing your mic not to connect properly.

[unseenreal]

Thanks for your advice KG, sorry it's taken so long to get back with a reply. I've been on a bit of a journey of discovery. I think the simple fact is that the output from the ATR25 was too low and the mic preamp background noise therefore became much more noticeable. Unless of course the one I got was particularly low on output, I don't know.

Anyway, I borrowed a Shure SM58 and made up a short cable to go from XLR to 3.5mm stereo jack (wired in mono) and tried it out. Wow what a difference, background noise almost gone, surprisingly good recording of acoustic guitar and vocals with the mic on a tabletop stand about 2 feet away. So then I tried my AKG C1000S condenser mic with 9V battery, however far too quiet, almost inaudible. So after a bit more pondering and internet trawling (I had a look at variuos mic preamps (from home made to expensive) and some mixers and some hard disc recorders) I ended up taking back the ATR25 to the marvelous Digital Village in Southampton, UK and getting a brilliant little Tapco Mix 60 mixer fo a mere £46. What a great piece of equipment, the sound quality is excellent and means I can get top quality recording on the NHF800 through line in. I can even attach an effects unit through the aux out/in loop to add some reverb if required.

If you are trying to get a good quality recording of live music or speech and don't mind a small amount of external equpment, this is a good solution. Here's a picture [attachmentid=2079].

Obviously not for covert recorording but excellent for capturing rehearsals etc. I would go so far as to say that I see no particular reason why you couldn't end up with a semi pro demo with this equipment. And that's what I intend to do!!!

[Recede]

any suggestions for covert recording?

[King Ghidora]

Small mics from either Sound Professionals or Giant Squid and a battery box should make recording in stealth mode work quite well.

[A440]

Small mics from either Sound Professionals or Giant Squid and a battery box should make recording in stealth mode work quite well.

I use Sound Professionals BMC-2 (with clips), tiny mics on thin wires, smaller than your pinky nail. Get them with clips, which are essential.

http://www.soundprofessionals.com/cgi-bin/gold/item/SP-BMC-2

Check ebay for them, too--sometimes Sound Pros knocks off a few dollars and sells them directly there.

For a battery module I use the Microphone Madness Miniature Classic:

http://www.microphonemadness.com/products/mmcbmminminc.htm

You can hear what they sound like in the Gallery (Live Recordings) under my album.

The Giant Squid sound samples have always made me turn away from them. King G, have you used Giant Squids? Do the actual mics, as opposed to the Giant Squid samples, not have that horrible exaggerated midrange and lack of bass I hear in their B-52's and Blue Notes samples?

Edited November 12, 2006 by A440

[Recede]

I use Sound Professionals BMC-2 (with clips), tiny mics on thin wires, smaller than your pinky nail. Get them with clips, which are essential.

http://www.soundprofessionals.com/cgi-bin/gold/item/SP-BMC-2

Check ebay for them, too--sometimes Sound Pros knocks off a few dollars and sells them directly there.

For a battery module I use the Microphone Madness Miniature Classic:

http://www.microphonemadness.com/products/mmcbmminminc.htm

You can hear what they sound like in the Gallery (Live Recordings) under my album.

The Giant Squid sound samples have always made me turn away from them. King G, have you used Giant Squids? Do the actual mics, as opposed to the Giant Squid samples, not have that horrible exaggerated midrange and lack of bass I hear in their B-52's and Blue Notes samples?

i just ordered a pair after i heard how good your recordings were. however atm i have CSB's which have a supplied battery box but the recordings in Line-in are still a significantly weak signal and i have a couple gigs i want to record in the next couple of days (not enough time for Sound Pros to arrive [Australia]) so if i was able to find a battery box somewhere instore before then would i be able to put a battery box inbetween the battery box and line-in input and expect a gain in volume? or would i have to go preamp? OH and the CSB mics dont even have much volume in mic-in without the connection to the battery box (if volume at all im not sure if without connection to the battery box if it cuts out the whole signal[weird setup with the battery box]) Thankyou.

Edited November 12, 2006 by Recede

[A440]

That's strange. The Core Sounds should be better, if anything, than the BMC-2--they're certainly more expensive.

Do you have the line-in gain up around 20? Maybe you got very low-sensitivity ones? Or could there be something wrong with the battery box? Are the batteries fresh?

You should email Core Sound and ask about the low level. I had Core Sound budget cardioids for a while, and I didn't like the cardioid sound (lacked bass), but they were low-sensitivity and I still got plenty of signal.

I don't think a second battery box would help, and you're going to end up with a jumble of wires and boxes that you're trying to stealth into the show. The battery box sends power TO the mics, not into the unit, so you could also try mic-battery-box--Mic-in and see if that gives you enough (or too much) signal, or just mic alone into mic-in. Under Rec Settings you should be able to switch Mic Sensitivity to high (though I don't know what unit you have), which affects the mic jack. Test it with your home stereo.

You can get my whole setup for the cost of a preamp, and it sounds good with very pocket-sized equipment, so I think it's a better arrangement than adding another box.

Edited November 12, 2006 by A440

[Recede]

Do you have the line-in gain up around 20? Maybe you got very low-sensitivity ones? Or could there be something wrong with the battery box? Are the batteries fresh?

You should email Core Sound and ask about the low level. I had Core Sound budget cardioids for a while, and I didn't like the cardioid sound (lacked bass), but they were low-sensitivity and I still got plenty of signal.

I don't think a second battery box would help, and you're going to end up with a jumble of wires and boxes that you're trying to stealth into the show. The battery box sends power TO the mics, not into the unit, so you could also try mic-battery-box--Mic-in and see if that gives you enough (or too much) signal, or just mic alone into mic-in. Under Rec Settings you should be able to switch Mic Sensitivity to high (though I don't know what unit you have), which affects the mic jack. Test it with your home stereo.

You can get my whole setup for the cost of a preamp, and it sounds good with very pocket-sized equipment, so I think it's a better arrangement than adding another box.

Yes although 20 is too weak through Line-In i have to max it out to 30 so when i amplify there isnt such a significant noise issue. Yep i just bought new batteries.

I emailed them this

> hi i have a sony NH700 hi-MD and i found that i am unable to record with

> your CSB's(with the battery box) through line-in, also if i do not plug

the

> battery box to the mics when i use mic-in i also receive no sound. is this

> suppose to happen?

>

> If i get another battery box and plug it between the battery box and

line-in

> would i then be able to use line-in? thankyou.

response was

The battery box is required to power the CSBs.

The battery box is not a microphone pre-amp -- it only powers the

microphones.

If you NH-700 doesn't have a microphone pre-amp input, it is unsuitable for

recording from microphones unless you are recording an exceedingly loud

sound source. We strongly recommend that you get a recorder that is

designed to accept signals from microphones.

You could also buy a microphone pre-amp, but a good one will cost more than

a new MD recorder. We can't recommend the inexpensive microphone pre-amps.

Feel free to ask more questions.

........................................end of email

With the low cost ones they can be powered without the battery box through mic-in so the battery box would amplify the signal? thats the way i interpreted as CSB's need the battery box outright. yes mic-in works fine with battery box although i havent tested it with loud sound sources without the battery box so im not sure if it records just on a very low level or not. i think mine starts automatically on high sensitivity will have to try low sensitivity sometime(suggested for loud source recordings?).

yea i purchased your arrangement because of the lack of noise issues through line in (removing noise after a recording seems to distort the recording a bit weird) and it seems significantly louder without amplification.

the concert im going to will have three consecutive shows, i only need one decent recording, i would just go mic-in but the artist varies abit between songs but then line-in gives a weak signal, when amplified sounds fine sometimes a bit bassy

but has the noise issue. i will also be directly in front of the stage for all 3 if i dont get a decent recording on the first 2.

Thankyou for your help.

Edited November 12, 2006 by Recede

[King Ghidora]

The Giant Squid sound samples have always made me turn away from them. King G, have you used Giant Squids? Do the actual mics, as opposed to the Giant Squid samples, not have that horrible exaggerated midrange and lack of bass I hear in their B-52's and Blue Notes samples?

I have a single GS omni lav that I use for recording audio for my video projects. I know what you mean about the lack of bass in their samples. But I have seen a lot of people who are serious about recording swear by GS omni lav's and a battery box. It seems like I heard some samples that made me think they were better than the samples on the GS web site. You just never know about samples from a concert though because it's very hard to know what the original sounded like.

I was basically repeating advice that I've heard on boards for quite a while. I know I am very happy with my omni lav for voice recording. But of course the requirements for recording voice and music are very different. I actually prefer some roll off in the bass range for voice because it makes the voice easier to understand in a recording. I don't have a battery box. I use a single point Nady stereo mic for recording music. I haven't done any stealth recording in quite a while. When I did I used a Sony ECM-MS907 which is definitely weak in the bass range. But it was a highly recommended mic when I bought it.

I do think my GS lav is weak in the bass department but not so much too strong in the mid range. But again I have heard lots of people swear by them for stealth recording. They certainly are small enough for the job and they aren't susecptible to problems with not being pointed exactly at the source. I really like my GS but again I use it for a different purpose.

[A440]

It seems that the CSB mics need more power than my BMC-2. There are all kinds of mics, and some need more power; indeed, some mics need a whole separate power supply. From what he's saying, it seems you should run those mics through the mic jack and forget about Line-in.

Unfortunately, the mic preamp may overload if there's a lot of bass. Try testing at home with your stereo turned way up--does the recording through mic-in distort?

For your immediate recording, I suggest:

1) First night (or, if you can test it with an opening act and listen between sets): CSB-->Battery Box-->Mic-in with LOW sensitivity. High sensitivity is really for unamplified sounds like speech. Use Manual Level and keep it at 15/30 to 18/30--watch the meter if you can.

Good recording? Then read no further and have fun recording the remaining shows.

2) Distortion caused by big bass? Go to an electronics parts store--Radio Shack in the US, Maplin in England, I don't know what Australia has--and get a headphone volume control, just a volume knob on a cord with a stereo minijack on one end and a stereo plug on the other. My avatar is the Radio Shack version; Maplin has something that looks different called the VC-1. Shouldn't cost more than $10 US.

The volume control is what electronics geeks call an attenuator: it attenuates (cuts) the signal going through it.

Mic-->Battery box-->Attenuator-->Mic-In.

Turn the volume knob on the attenuator all the way UP (maximum) and it should still cut the signal enough to limit bass distortion. It may add a little noise, but nowhere near as much as amplifying a too-quiet signal. You also might want to make Manual Volume a little bit higher.

Using the attenuator limits the power going out to the mics from the MD unit's mic jack, but that shouldn't be a problem for you since your mics are getting their power from the battery box. I used to go mic-attenuator-Mic-in, and there's probably a recording or two in my album done that way, but the mic--battery module--Line-in gets better results. I still keep an attenuator around in case my battery module loses power.

3) If for some reason that doesn't work, on Night 3 just make a line-in recording at 30. At least you know you'll get somewhat usable audio.

Edited November 13, 2006 by A440

[Recede]

Thankyou, my battery box also has a switchable bass filter. also it works fine with the stereo but its hard to replicate the subs at the events and you pretty much have to guess it. i really appreciate the help

Edited November 13, 2006 by Recede