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Hiss: Mic Pre, A/D, D/A? MD-N707

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Hi all, it's my first post and my hope to use my MZ-N707 for field recordings brought me here to the forums, It's been great reading about the tweaks and tips. I've been reading stuff on this topic and I've ever so grateful for all the great advice, but I'm yet to find a definate answer to my questions.. huh.gif

Ok, I've been trying to do some very simple tests on the recorded sound quality of my minidisc, but I've yet to figure out the 'bottle neck' for my recorded material, I get considerable amount of hiss (maybe most people wouldn't mind it I guess, but I find it really annoying) when using mic in and 'line out' (headphones). :sad:

Basically I'd like to get the best sound quality when transferring material recorded by mic to minidisc and then onto my Mac. I am aware that SonicStage is out of the question which means that USB is out of the question.

So since I'll be using analog & possibly optical I got a few questions on the quality of my N707:

- What do you think is the main source of hiss? (I understand that it could be pretty much anything, but I'm using 'good' equipment with no auto rec vol etc.) As in what point of the (component) chain is there most noise added?

- Is there any point using external mic pre (with optical out? [is there any such pre? blink.gif]) for recording or are the components that transfer recorded data onto the actual disc too poor to really have any advantage from such pre?

- Will a rack minidisc player with optical out change the quality dramatically when transferring material from MD or does the 'hiss' happen before it actually is saved on the MD or before its been send to the optical out?

- I really wouldn't want to buy a separa pre or rack minidisc player so is there any other way to improve the quality of the recording that is being saved onto the MD and then send to my Mac? What kind of solutions have you been using and found useful?

Thanks in advance, I really appreciate all the suggestions.

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pjburnhill -

The 'hiss' is most definitely coming from the mic pre-amp in your MD unit. I have exactly the same problem.

I'm using the same mic (Sony ECM 907) with my Sharp MS722 unit, and the unusable noise-floor is present even before I plug the mic in.

The problem is, because the output of the mic is so quiet, you have to turn up the input gain on the MD unit, and that brings up the noise.

You have to buy a suitable mic pre-amp (try FEL mic amps if you're in the UK) to boost the signal before it gets to the MD unit, thus making you turn down the input gain, and resulting in less 'hiss'. FEL do a 3.5mm pre-amp designed for MD use and costs £105. They claim a 20dB boost. I'm planning on buying one as soon as I get my shiny new Hi-MD unit.

Trust me - the hiss is coming from your MD unit's mic pre-amp. Once you correct that, things will be fine.

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I have had many a poor recording from too much hiss. My investigation led me to a combination of loud self noise microphones, and even louder internal pre-amps.

Even when recording without anything plugged in you will get a certain amount of noise. This is generated by the electronics inside your recorder (I have noticed that when compairing the Sony to the Sharp, the Sharp is much quieter).

So what can you do about all this?

1. Keep your current equipment, and remove the hiss with some post software editing. I usually keep a template of my recorders noise print on file, and use that to remove the hiss from some of my recordings.

Keep in mind that removing the hiss also removes some other sounds, and depending on what you recorded it could make it sound worse.

2. By-pass the internal pre-amp by feeding the mic signal into the line in. This will result in almost no pre-amp noise at all. However, You will need to power the microphone with an external pre-amp or a simple power supply.

Note when using the much cheaper power supply only, you'll need a loud environment to record in.

Let us know how you solved this problem?

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Thanks guys,

I guess the problem is the mic pre and I could use noise reduction in Sound Forge or other software. I'm just not too keen on goin through hours of recording especially, like you said if you have to change the noise reduction parameters on different material.

Also that FEL mic pre looks promising, though still quite pricey. I've been looking into other mic pre options one being making it myself.

Here's one option http://www.geocities.com/ferocious_1999/md...micpreamp2.html

Any other cheap portable mic pre choices?

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pjburnhill -

Reactive's 2nd suggestion is a good one. If you go in at line-level then there will be no pre-amp noise because you won't be using it. You'd obviously need to get a box that'll turn your mic into line-level.

Avoid getting into noise-reduction if you can help it. Although handy, NR can produce artifacts and often make the recording sound worse than it originally did. As a professional sound engineer (I spend my days recording and mixing voices and other material for TV and radio), I can state through experience that it is far better to get things right at the recording stage, than have to fiddle with de-noisers. I once had to noise-reduce, noise-gate and EQ a 5-minute party political broadcast where the party leader spoke non-stop. Why? Because the location sound guy didn't think the loud air-con noise would be a problem...So, get the recording as good as you can get it.

The noise you are getting is coming from the pre-amp. Plain and simple. Boost the source level, take down the mic gain (or even better go line-in) and your recordings will sound nice.

Portable minidisc units are aimed at domestic users, so they don't have high-quality Focusrite pre-amps built into them (that'd probably make them less portable too!). Instead you have to deal with what Sony/Sharp build themselves, which are noisy pre-amps, but that shouldn't deter enthusiast like us from getting top-quality recordings. Check out the various pre-amps and boosters available, and you'll have no excuse for 'hissy' recordings!

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Cheers 722Forever, that's really helpful. As you said, I really wouldn't like to get into NR, if I can help it and I can. :smile:

One question though, won't the 'headphones' output add quite a bit noise as well so should I try to run all recorded material to my computer trough desk minidisc unit's optical out if I can find one? Or have you experienced this problem with 'headphones' output at all?

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The headphone output is a dual mode output. You should be able to go into the menu system of your recorder and change the output from audio to line. Then your headphone jack will be functioning as a line-out. smile.gif Cool eh!!

Sharp was one step ahead of sony on this one, you simply turn up the volume past 28 and it magically becomes a line out signal (unaffected by tone controls).

Good luck, now go and record with some of most portable high tech equipment ever made.

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Glad to see I'm not alone in concerns about "hiss" on mic recordings. I've only recently begun using MD (Sony MZ NH1) for recording music exam candidates performances, some of whom sing/play very quietly!

I initially purchased an MS 909A mic, good quality on reasonable sound levels, too much hiss on very quiet passages. So I tried and have subsequently bought a mic that many users of this forum would consider "unsuitable", I suspect, the Audio-Technica ATR 25. It is officially a "Video" mic but so far has proved absolutely ideal for the purpose for which I need it. Its only drawback is the very short connecting lead, about 8 inches, but I also bought a "headphone extension lead" which allows the mic to function at a greater distance from the recorder. I'm almost certainly going to fit at least one of the spare clamp filters which came with the NH1 to this extended mic cable to attempt to prevent any unwanted breakthroughs, but, so far so good.


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Lot's of good advice here. Let me throw in a a little more, as I've done a lot of MD recording of live music where quality was important.

First, there -are- a lot of issues with your built-in preamp. It is fairly noisy, overloads pretty easy, has limited frequency response, and doesn't match up to the quality of an external preamp. However, just adding an external preamp doesn't solve all your problems. You now have to deal with an extra box, power issues, cords, more level setting, etc.

Here are some hints to make the most of your unit as-is:

1) forget whatever noise you hear with nothing plugged in. Unterminated mic-preamps will pick up all sorts of electrical noise that goes away with a mic plugged in.

2) make sure you are setting the preamp gain to the lowest possible level to get a decent recording level. Since we desperately want to avoid digital clipping, you should be pretty conservative about the level setting anyway.

3) never, ever use the automatic gain (aka auto level) for mic recordings. It produces all sorts of artifacts (popping, "breathing", clipping, etc.).

4) get a better microphone. The Audio Technical A-T 822/824 are nice stereo condensor mics made especially for use with portable recorders and camcorders. They are self-powered, easy to position, fit a regular mic stand, and provide a good level signal to your MD unit.

5) forget noise reduction software or hardware. Reduce noise at the source, don't try to remove it later. All noise reduction methods are a compromise and are not suitable for most digital recording methods (unless you're recording in a physically noisy environment and need to remove that noise during editing).

Alternatively, you can get into the area of using an external mic preamp. Sound Professionals makes one just for use with portable devices. A more budget minded, but less portable, solution is M-Audio's Audio Buddy mic pre. It is about $99 retail, has two decent preamps, phantom power for professional condensor microphones, and a selectable output level (-10db or +4db, -10 being the choice for your MD unit or any consumer gear). Also, with that in hand, you can buy a pair of inexpensive condensor mics that will shame your little Sony microphone. Oktava's MC1202 is a great choice and are often on sale for under $120 a pair.

Hope this helps some, and good luck. Half the fun is trying to get the most out of what you have, so start with that.


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All good advice ProAudioGuy.

I totally agree with the last bit - experiment with what you've got. I've been using a little Sony ECM907 mic for a couple of years with my Sharp MS722 recorder. Last week I treated myself to a Hi-MD (Sony NH900) and a little pre-amp unit. I'm itching to get out and experiment with it, but have very little time at the moment!

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