Mic Upgrade Versus Preamplifier

[Von Recklinhausen]

Hi at the live recording forum:

I have recently initiated in live recording. I am specially interested in recording very quiet classical music and ambient sounds (bird-singing, water sounds, etc). My current equipmet is a Sony MZ NH1 minidisc and a Microphone Madness microphone (MM-BSM-1). I am quite satisfied with the recordings I have made until now, but I find that in ambient sound recordings I get an inherent noise or self-noise quite disturbing (at least for me). In the MM microphone specifications is indicated a signal to noise ratio of 58 dB, 1khz at 1 pa.

In an attempt to reduce the self noise, I comtemplate two possibilities:

1. A more silent microphone, that is, with a S/N ratio of 65 dB or greater, such as the Microphone Madness "Sennheiser driven" omnis stereo microphones or the Sound Professional SP-CMC-8 or BMC-10.

2. A pre-amplifier, such as the Reactive Sounds Boost Box or some equivalent model from Sound Professionals.

The Boost Box specification is S/N ratio 92 dBv EIN 1.0 v. At this point my first doubt arises: I understand that the combination of my actual microphone (S/N ratio 58 dB) with the Boost Box will raise the "total" S/N ratio to 92. Is that right?

Second question: What of the two possibilities will provide more silent recordings?

More questions, if allowed: Do you recommend me any other microphone with similar or greater S/N ratio, or any other way to get silent recordings?

That is a lot of questions, I know, but if you are so kind to help me to find the right answer I'll be very grateful.

[A440]

Can't answer all of your questions, but most of your noise is likely coming from the MD's own preamp. An outboard preamp through Line-in, bypassing the mic preamp, should provide a great improvement even with your current mics.

[greenmachine]

The Boost Box specification is S/N ratio 92 dBv EIN 1.0 v. At this point my first doubt arises: I understand that the combination of my actual microphone (S/N ratio 58 dB) with the Boost Box will raise the "total" S/N ratio to 92. Is that right?

No, the quietest preamp won't improve a noisy microphone, you would still have a S/N of only 58 dB. A chain is only as strong as its weakest link.

Second question: What of the two possibilities will provide more silent recordings?

Most propably the first one, i don't know about the truth of the rumor how noisy internal MD preamps really are, if it's really worth to use a quieter, external preamp, but if you want to be on the safe side...

If the microphone's noisefloor is higher than the preamp's n. depends on the microphone's sensitivity, impedance and propably many other factors. But most propably it is.

More questions, if allowed: Do you recommend me any other microphone with similar or greater S/N ratio, or any other way to get silent recordings?

I'm afraid i can't, but i can recommend you a microphone discussion group with lots of experts instead:

http://groups.yahoo.com/group/micbuilders/

Edited June 19, 2005 by greenmachine

[dex Otaku]

In an attempt to reduce the self noise, I comtemplate two possibilities:

1. A more silent microphone, that is, with  a S/N ratio of 65 dB or greater, such as the Microphone Madness "Sennheiser driven" omnis stereo microphones or the Sound Professional SP-CMC-8 or BMC-10.

S/N is not the end-all-be-all. A microphone with a higher sensitivity rating and/or a lower self-noise figure would likely benefit you more than one with a higher S/N.

2. A pre-amplifier, such as the Reactive Sounds Boost Box or some equivalent model from Sound Professionals.

This is probably your best bet.

Second question: What of the two possibilities will provide more silent recordings?

A better preamp would be my first bet.

More questions, if allowed: Do you recommend me any other microphone with similar or greater S/N ratio, or any other way to get silent recordings?

Like I said, sensitivity and self-noise ratings are just as if not more important than dynamic range and S/N ratio.

If you're really interested in increasing the dynamic range of your recordings:

* Get balanced microphones and cabling

* Use mics that are properly biased if they need power [not with just 1.5V or something, but full 12-48V phantom power]

* Use a low-noise, high-gain mic preamp with balanced inputs

and lastly

* Consider using an external A/D convertor

[A440]

i don't know about the truth of the rumor how noisy internal MD preamps really are

←

They're noisy. Here's 10 seconds of birds recorded with mic via mic-in (high sens, AGC) followed by 10 seconds with Boost Box preamp at max gain through line-in.

http://forums.minidisc.org/index.php?act=m...&cmd=si&img=706

[Von Recklinhausen]

S/N is not the end-all-be-all.  A microphone with a higher sensitivity rating and/or a lower self-noise figure would likely benefit you more than one with a higher S/N.

This is probably your best bet. 

←

Thanks, dex, but I thought that S/N ratio was a measure of the micro's self-noise. What's exactly the difference?

[Von Recklinhausen]

They're noisy. Here's  10 seconds of birds recorded with mic via mic-in (high sens, AGC) followed by 10 seconds with Boost Box preamp at max gain through line-in.

http://forums.minidisc.org/index.php?act=m...&cmd=si&img=706

←

What a wonderful example! that's exactly what I referred as disturbing self-noise, and the improvement with the Boost Box is surprising. I think that the Low Cost Core Sound Binaurals are equivalent in specifications to the Microphone Madness MM-BSM-1, so I supposse the results of combining the MMs with the pre-amp would be similar. Thanks.

[greenmachine]

They're noisy. Here's  10 seconds of birds recorded with mic via mic-in (high sens, AGC) followed by 10 seconds with Boost Box preamp at max gain through line-in.

http://forums.minidisc.org/index.php?act=m...&cmd=si&img=706

←

Very interesting, thank you. Unfortunately you can't compare it directly in your provided sample. It's true that the noise is lower for the second part, but at the same time is the signal (birds). It shows that the boost box has less gain at the max. setting than the MD preamp at high sens. setting. If you boost the second part to a comparable volume via software, there is not much difference in the signal to noise ratio (as expected).

The noise in the second part sounds somewhat brighter than the noise in the first part (almost like white noise to pink noise), but volumewise it's virtually the same in the end. If this difference in the noise characteristic comes from the preamp itself or the (under-)powering of the microphones is hard to tell.

Here's an edited sample for direct comparison (boosted the second part by 8 dB in Audition):

http://forums.minidisc.org/gallery/1119229..._60_3688677.wav

[The Low Volta]

It's true that the noise is lower for the second part, but at the same time is the signal (birds) ...The noise in the second part sounds somewhat brighter than the noise in the first part (almost like white noise to pink noise), but volumewise it's virtually the same in the end.

I must agree with greenmachine here... when I listened to the sample, I just increased playback volume for the last 10 sec so the birds sounded equally loud but the noise level increased with that, so I too noticed very little difference in noise (volumewise)... (and greenmachine's adjustment shows that pretty good)

strange, as I always thought an external pre-amp would make such a big difference

...perhaps we could ask Mr.Soul who has got the Boostbox to record a continuous low volume signal (or the same track played through the same speakers at the same low level twice) once with and once without the extenal pre-amp so we could get a clearer sample to compare (at least we could make sure that the incoming signal was just as loud/quiet...so we can use that to precicely match the levels of both recordings and compare noise). Or is this a bad idea?

greetings, Volta

[dex Otaku]

Thanks, dex, but I thought that S/N ratio was a measure of the micro's self-noise. What's exactly the difference?

←

http://en.wikipedia.org/wiki/Audio_system_measurements

http://www.dpamicrophones.com/page.php?PID=35

[Microphone University's "How to read Microphone Specs", very useful]

[greenmachine]

...perhaps we could ask Mr.Soul who has got the Boostbox to record a continuous low volume signal (or the same track played through the same speakers at the same low level twice) once with and once without the extenal pre-amp so we could get a clearer sample to compare (at least we could make sure that the incoming signal was just as loud/quiet...so we can use that to precicely match the levels of both recordings and compare noise). Or is this a bad idea?

←

A good idea, but i think it's unfair to compare it when the mics are powered differently [9v from the boostbox vs. the low volta(ge) from the md preamp] - on the other hand, it seems not to make such a huge difference in the end.

[dex Otaku]

A good idea, but i think it's unfair to compare it when the mics are powered differently [9v from the boostbox vs. the low volta(ge) from the md preamp] - on the other hand, it seems not to make such a huge difference in the end.

←

The difference is in the max SPL the mic can transduce. If you're recording low-level sounds, there is no benefit to higher bias voltage that I'm aware of.

[The Low Volta]

The difference is in the max SPL the mic can transduce.  If you're recording low-level sounds, there is no benefit to higher bias voltage that I'm aware of.

←

I believe I read somewhere that the frequency responce also benefits from being fed a decent voltage...but don't kill me if this is utter gabble, as I only vaguely remember it and I'm not very wise in the way of mics and audio

besides, if Mr. Soul has a battery box as well, he could do:

- mic->batt box->mic in (=MD pre-amp + 9V)

- mic->boost box->line in (=external pre-amp + 9V)

if this makes sense (and doesn't introduce extra noise by adding a battery box) all we need is Mr.Soul and we have ourselves a test

Volta

[greenmachine]

- mic->batt box->mic in (=MD pre-amp + 9V)

- mic->boost box->line in (=external pre-amp + 9V)

I suggest this to be included in the test as well to see if there is any benefit of a higher bias voltage for low-level sounds:

- mic->mic in

[greenmachine]

I just did a comparison between the internal mic preamp of my mz-r909 and my self-made low noise preamp (which i originally built for my Creative Nomad Jukekox 3). I am amazed how similar they sound (except for a slight channel balance difference of approx. 1dB)! The noisefloor is virtually the same in this test, so i conclude it's the microphone's self-noise what we hear here. I've been careful not to introduce additional noise. Looks like you have to have microphones with much lower self-noise to be able to hear the noise generated by the preamp.

How i did the test:

Level 30/30 for both mic-in (low sens.) and line-in, recorded in SP (i'm not a 'HI-MDer' yet, heh).

1st part: mic->battery box->mic-in

2nd part:mic->external preamp->line-in.

Transferred digitally. First part amplified by 18 dB, second part by 15 dB in Audition to roughly match loudness. I couldn't test the mics directly to mic-in, since they are modified and require a reversed voltage to operate.

Test sample:

http://forums.minidisc.org/gallery/1119229..._60_1503080.wav

Nevertheless, i'd still like to see some tests with the popular 'boost box' or other external preamps.

Edited June 20, 2005 by greenmachine

[The Low Volta]

Nevertheless, i'd still like to see some tests with the popular 'boost box' or other external preamps.

I have PM'ed mrsoul and he wants to do the test, but he hasn't got a battery box any more, so it will be 'mic->mic in' vs 'mic->boostbox->line in'

[A440]

I'd like to hear what mrsoul comes up with, but in the meantime I booked the birds for another recording session.

According to the Reactive Sounds website, the Boost Box at zero gain is the equivalent of a battery box.

The first link is the raw recordings.

http://forums.minidisc.org/index.php?act=m...&cmd=si&img=724

On the second one, I did a quick-and-dirty Amplify in Audacity to make the four segments more or less equivalent.

http://forums.minidisc.org/index.php?act=m...&cmd=si&img=725

[greenmachine]

Thank you very much again.

What i can hear is that the noise in high/low sensitivity mode seems to be approx. the same after amplifying, the BoB at zero gain seems to add lots of noise - unlike a 'real BaB' and the BoB at max. gain through line-in seems to have a 'brighter' sound than the internal preamp.

It's really hard to compare the noise levels in these samples though because of the inconsistent, unpredictable soundsources: The birds don't sing equally loud all the time and there's quite some of (traffic-?) noise in the background.

If you could reapeat the test in your living room with closed windows and doors, (re-)playing a specified music sample through your Hi-Fi system at a low volume, it would be wonderful.

*BaB=Battery Box

*BoB=Boost Box

BTW, why can't we upload FLAC files?

[greenmachine]

Small diaphragm microphones tend to have higher self noise than their larger brothers in general. Maybe you should consider larger diaphragm mics for recording quiet sounds if you can live with their other limitations.

http://www.dpamicrophones.com/page.php?PID=28

[mrsoul]

Ok, my 2 TEST samples are now in the Gallery.

TEST Gallery Samples

These were both PCM with manual recording at 30/30 with the Boost at Max and the Mic Sens set to Low.

I never record LIVE music with the Boost Box going 30/30 or Max gain so I don't know if this TEST really shows the benefit of the Boost Box. I usually set around 21/30 line input and use less than half of the gain on the Boost Box and I have never heard the amount of noise you get with Max Gain and 30/30 on the Boost Box. It sounds almost the same to me on both samples. What do you think? Oh well, more later.

[ozpeter]

Not long ago I did some tests using a CD as a source into the line in and then the mic in. The CD player has a digital level control enabling me to attenuate it enough to record into the mic input. Having recorded a bit of the same track each time, I then paused the CD player to enable me to record just noise. Although I did my best to make the two recordings at comparable levels, I normalised them in the PC afterwards to ensure that the signal part was identical, enabling the noise to be compared. Trouble is, I forget what the result was, although the NH900 mic input appeared to be no disaster. I guess I must either find the previous post here again, or repeat the test.

I've also got another possible route for evaluation, which is the Sennheiser mic preamp I use with Sennheiser MKH series mics - seriously expensive and about as low noise as you can get. That can output at either line level or mic level, so that might make the basis for an interesting experiment.

[Edit - I've now found the info and the result was that "Peak noise level on the mic input is about -62dB, compared with -72dB on the line input".]

Edited June 22, 2005 by ozpeter

[greenmachine]

Thank you, mrsoul.

Again, the BoB's noise sounds brighter and thus slightly louder in the upper frequency range than the iMP's noise. In the lower freq. range it's virtually the same. For direct comparison, i've boosted the iMP's recording by 2.3 dB and chose a suitable selection. Because of this difference, i'd be interested which one of these two preamps sounds more neutral. Does the BoB sound bright or does the RH10's iMP sound dull? Or is this difference only in the noise figure? In my test there was no such more or less significant difference. A short test with louder, treble-rich music would be helpful.

Attachment: The short selection for direct comparison, 1st part BoB, 2nd part iMP:

http://forums.minidisc.org/gallery/1119229...3_60_184127.wav

*iMP=internal microphone preamplifier

BTW, where does the low frequency rumble come from? Did you have a washing machine running in the next room?

Edited June 22, 2005 by greenmachine

[AllanH]

Hi - as usual I'm late in on this thread.

I've been recording nautural sounds & birds for about a year now using HiMD so maybe my comments will help.

I too found my early recordings too noisy - I was using Sony ECM909, 959, 999 electrets. I've use a preamp (FEL, www.felmicamps.co.uk) and that helps, but the biggest single improvement was a switch to a Rode NT4 mic. This instantly gave me clearer, cleaner recordings.

There a few points to watch out for though:

- the mic is very sensitive to movement and wind noise. A well-damped mount and windshield are essential for outdoor use except in perfectly still conditions. A low frequency roll-off filter (high pass) is also useful.

- the mic comes with an unbalanced lead, but this contains a pad resistor which reduces the signal level a bit. I've made up a lead which unbalances the signal from the mic but does not include the pad resistor. This keeps the high signal level the mic produces and reduces the need for later amplification.

The NT4 is fine for ambient sounds - streams waves etc. But if you want to record birdsong without noise, things get more serious. The bird recording fraternity largely uses Sennheiser MHK series mics because of their low noise, but ME series mics are also used. These are good for 'soundscapes'. If you want clear, quiet recordings of individual birds singing and you cant get close to them, you will need a microphone in a parabolic reflector. Several ways of doing this, but the most portable/lightweight is a Telinga. You might like to try: www. wildlife-sound.org

Problem with much of this kit is that it works against the lightweight ethos of MD. Microphones often need a phantom power supply, use bulky XLR connectors, Mid-Side stereo recordings need a decoder box to allow headphone monitoring, you might use an external pre-amp ADC - it all builds up. Sooner or later you start wondering about a specialist preamp (SQN?) and maybe a different recorder (Fostex, Sound Devices) - be careful about being sucked in!

(Bulky XLRs aren't all bad - I had my mic, windshield and tripod blown over a seawall while recording waves. Luckily everything back to me was connected with locking XLRs and I simply hauled the rig back up again using the mic cable. Would have lost the lot with 3.5mm mini-jacks.)

Regards

AllanH

[mrsoul]

BTW, where does the low frequency rumble come from? Did you have a washing machine running in the next room?

←

No, I turned off everything in my house before the test and put the cat in the yard. I even turned off the central A/C in my house. That is a sacrifice in South Carolina in the middle of June, let me tell you! Is it possible you were hearing the cello from the source CD? I can try with just some vocals or electronic source later. Thanks for the remix.

I did find the Bob to be brighter in the higher freqs as well.

[greenmachine]

Is it possible you were hearing the cello from the source CD?

I don't think so, sounds more like a passing-by train from one mile distance. Propably it's only low frequency noise from the mics.

http://forums.minidisc.org/gallery/1119229...3_60_219693.wav

[dex Otaku]

i'd be interested which one of these two preamps sounds more neutral. Does the BoB sound bright or does the RH10's iMP sound dull? Or is this difference only in the noise figure? In my test there was no such more or less significant difference. A short test with louder, treble-rich music would be helpful.

Suggestion, keeping in mind that the playback system becomes the reference when doing this:

Situate the mic in front of your stereo speaker.

Play a sweeptone, recording with the iMP [i love your acronyms!].

Do the same, recording with the BoB. You now have a point of reference [the stereo system] with a single test signal [the sweep], a single mic, and a basis for comparison between the preamps.

You might want to put to mic in front of the tweeter, btw.

[dex Otaku]

I don't think so, sounds more like a passing-by train from one mile distance. Propably it's only low frequency noise from the mics.

http://forums.minidisc.org/gallery/1119229...3_60_219693.wav

←

It's possible that it actually was a passing train. I have made recordings with the Sony ECM-MS907, out in the country, where train sounds that I wasn't aware of myself at the time are audible in the noisefloor, especially in the lowest octave. [Train tracks would have been at least 3 miles away, by the way.]

[greenmachine]

Suggestion, keeping in mind that the playback system becomes the reference when doing this:

Situate the mic in front of your stereo speaker.

Play a sweeptone, recording with the iMP [i love your acronyms!].

Do the same, recording with the BoB.  You now have a point of reference [the stereo system] with a single test signal [the sweep], a single mic, and a basis for comparison between the preamps.

You might want to put to mic in front of the tweeter, btw.

←

If anyone wants to do this, but doesn't know how to generate a sweeptone, here's one, 0.02-20kHz:

http://forums.minidisc.org/gallery/1119771..._60_259636.flac

Edited June 26, 2005 by greenmachine

[mrsoul]

It's possible that it actually was a passing train.  I have made recordings with the Sony ECM-MS907, out in the country, where train sounds that I wasn't aware of myself at the time are audible in the noisefloor, especially in the lowest octave.  [Train tracks would have been at least 3 miles away, by the way.]

←

That is very possible. My house is about 500 feet from the Southern Railroad line. There is a patch of woods and a 2 lane road between my street and the tracks. It's still an active line. Maybe I didn't notice. I will take another listen. But there was nothing, not even a ceiling fan moving in my house. You can however hear the clock in my living room above the fireplace...

[Keith]

Well guys, I've been following this topic with interest, not least because I want to solve similar problems. However, I'm not sure where this all leads. I think the conclusions are:

1. The internal preamp isn't as bad as everyone first thought. So maybe buying an external preamp won't provide all the benefits I'm looking for.

2. For recording quiet sounds, the first step should be to maximise the signal going into the mic (e.g. get closer). The recording level can then be kept low which minimises noise from the preamp.

3. If this doesn't work, try a better mic with lower self-noise before shelling out for an additional preamp.

What do you think? Happy to be shot down - as long as I can learn how to make better recordings.

Keith

[greenmachine]

4. Never use the BoB at or close to zero gain.

[Reactive]

Hi Guys,

It's probably no surprise to hear that I have been following this thread for a while. I felt it important to keep in the shadows until all comments good and bad had been put forth.

The Boost box was designed out of necessity. My own personal recording experiences often left me feeling frustrated at the equipment limitations. Limitations such as:

1. Internal pre-amp noise

2. Internal pre-amp overloading in loud recording environments.

3. The lack of a reliable clipping aid to prevent pre-amp overload in dark locations.

4. The lack of proper power to the microphone elements, as the MD recorders output power was far too low.

5. The lack of an on the fly adjustable gain.

Basically I required an all-in-one solution. The Boost box was born. Nothing else like it on the market, does what it says and does it well.

I am intrigued at the experiements that you have conducted on the internal noise, and I will run my own to see if I get the same results.

I will conclude with this, internal equipment noise is the most costly, most difficult thing to reduce, without creating a $1000 pre-amp. You can only ever get it down to a manageable level. I can create a very good recording at Max gain with the Boost box, and without having to further amplify in post software editing. Every 6bd of amplfication doubles the noise floor, and I try to avoid this at all costs.

Thanks for your very detailed comments in the previous posts

Gerry

www.reactivesounds.com

[Von Recklinhausen]

I'm sorry I have been outside during some days. It seems that the best solution for getting quiet recordings would be a better microphone such as the Rode NT4, as Allan H says. Any other suggestions about a "better microphone"?

[A440]

For small, stealthy mics, the wonderful ambient recordings at

www.quietamerican.com

are made with mics from Sonic Studios.

http://www.sonicstudios.com/

Others I have seen recommended--but not used due to budget constraints--are DPA.

http://www.dpamicrophones.com/

[clyborne]

I'm happy to report that there is no need to use an external preamp to get very, very good, low noise, high gain performance out of the Sony HiMD built-in mic pre. In tests I've been running using both the Rolls PB224 and the Art Phantom II portable phantom power supplies ($70 and $45) to enable the use of low noise, condenser mics, the EIN rating of the Sony mic is no worse than -118 dBu-- you'd have to spend a lot to get an external pre that's better. The trick turned out to be compatibility with the PIP circuit and these two phantom power modules can cope with it (many others I tested cannot). The preamp chip used by Sony has very low noise, it was a matter of getting around the PIP conflict.

Below is a link to a QuickTime Movie that has 2 Rode NT1-A mics with 5.5dB(A) self noise first run through a Sound Devices 722 pre/recorder and then through the Rolls and Art phantom modules to the Sony NH-900's 3.5mm stereo mic input.

http://www.uwm.edu/~type/Mic%20Preamps/Por...rtv01SorIMA.mov

You can hear for yourself that the noise produced by both the $2200 pre/recorder and the lowly NH-900 pre/recorder is on par with the self noise of this extremely quiet mic. The good news, of course, is that recordists on a budget are no longer restricted to using PIP mics. With the addition of a phantom supply module to your HiMD recorder, you can try some of the many, new (phantom-powered) condenser mics that have come out in recent years. The Studio Project C-4 mics, for example, look interesting at 3 oz's each, with cardioid and omni capsules and 16dB(A) self noise. (The mentioned mic with 58dB S-N has 36dB(A) self noise in comparison.) The Rode NT1-A's are definitely an amazing match for HiMD recordists who want to bring home recordings from quiet settings. Note that the Sony mic pre has 5dB more gain than the 722's pre so even lower sensitivity mics (safely anything >10mv/Pa?) should work very well too. Almost all PIP compatible mics have fairly high self noise (and low output) but if your condenser mic(s) happens to also run on 48volts phantom, it will probbaly show as much improvement running through one of these portable phantom power supplies as through a $800 external preamp. In the test, a Rode NT4, acquired 13dB more gain after liberation from PIP compromise with a Rolls PB224 or Art Phantom II.

The two portable supplies perform identically. The Rolls outputs only 48 volts and the Art has 12 volts as well. The Rolls has a nicer battery slot, but is a tad bigger. You can use a standard 2-xlr female->stereo mini plug unbalanced adapter cable to get from the box to the mic input.

The phantom supplies might also liberate older MD's DATs.etc. Feel free to send reports to me at the email address in the movie. Rob D.

= = =

Hi at the live recording forum:

I have recently initiated in live recording. I am specially interested in recording very quiet classical music and ambient sounds (bird-singing, water sounds, etc). My current equipmet is a Sony MZ NH1 minidisc and a Microphone Madness microphone (MM-BSM-1). I am quite satisfied with the recordings I have made until now, but I find that in ambient sound recordings I get an inherent noise or self-noise quite disturbing (at least for me). In the MM microphone specifications is indicated a signal to noise ratio of 58 dB, 1khz at 1 pa.

In an attempt to reduce the self noise, I comtemplate two possibilities:

1. A more silent microphone, that is, with  a S/N ratio of 65 dB or greater, such as the Microphone Madness "Sennheiser driven" omnis stereo microphones or the Sound Professional SP-CMC-8 or BMC-10.

2. A pre-amplifier, such as the Reactive Sounds Boost Box or some equivalent model from Sound Professionals.

The Boost Box specification is S/N ratio 92 dBv EIN 1.0 v. At this point my first doubt arises: I understand that the combination of my actual microphone (S/N ratio 58 dB) with the Boost Box will raise the "total" S/N ratio to 92. Is that right?

Second question: What of the two possibilities will provide more silent recordings?

More questions, if allowed: Do you recommend me any other microphone with similar or greater S/N ratio, or any other way to get silent recordings?

That is a lot of questions, I know, but if you are so kind to help me to find the right answer I'll be very grateful.

←

[greenmachine]

This is very good news indeed, i always supposed the internal preamp to be of very high quality. Thank you for confirming it in this meaningful test.

[Gweeble]

This is very good news indeed, i always supposed the internal preamp to be of very high quality. Thank you for confirming it in this meaningful test.

←

Hi Clyborne, Greenmachine et al ~

I assume what you are talking about is that there is a compatability issue between the HiMD recorder and an external phantom-power supply, since the recorder is already sending out a phantom voltage, which a phantom-voltage generating power-supply wouldn't normally have to deal with. Normally a phantom supply would have simply a mic input to look into, without an incoming voltage at that connection.

Am I following you?

What is PIP, the Sony term, Plug-In-Power?

Thanks for the great discussion, It's cool that you guys with test gear are interested and have the time and tech ability to experiment, and the community spirit to share this with us. Love your attention to detail. Appreciations extolled!

(The results are also great too!)

Gweeble

[clyborne]

Its a pleasure to help if I can. Thanks for your kind comments.

That's correct about the phantom conflict. I do not fully understand the nature of the conflcit between most portable phantom power supplies with the HiMD (and other) mic preamp "Power In Plug" (PIP) circuits. The bad result is a loud fizz and line hum. I've asked on a few lists, but no one has figured out why these two units work and others (even expensive ones) do not. I came across the discovery while trying to determine what the EIN (Equivalent Input Noise) of the NH-900 HiMD mic preamp is by trying to get a low noise mic to work with it. I was surprised as any one with the result! Klas Standberg (Telinga Microphones) has been stressing for years on the naturerecordist list that consumer grade mic pre chips have good specs but that something could be preventing them from working correctly. We owe Klas thanks.

Another curious thing is that what ever is causing the PIP/phantom supply conflict might be related to the poor performance of some PIP "compatible" mics when used as recommended. The Rode NT-4 mic gaining 13dB of output when used with an Art/Rolls over 9 volt PIP is one example. If I owned a mic that had phantom power capability and an HiMD recorder, I'd drop $45 to try the phantom supply unit in a heartbreak. They're small enough so that you can "velcro" the HiMD recorder to it and still have a one palm recorder. Maybe one of the industrious MD accessory businesses out there will make a smaller unit soon!

I do tests because one really can't believe everything dealers and manufs claim about their products. Its ridiculous, when you think about it, that no one tried what I tried before. I too spent a lot of money on pres instead of on better mics because I accepted the myth that one needs an external pre with consumer grade mic pres to get low noise performance with lesser expensive recorders. It is not that hard to borrow gear from each other and run simple comparison tests. _When_ manufs bother to provde manufs provide specs, they are an indication. What matters to us is how the components perform in combination, "mics with pre" in the field with high gain-- they way you use it, etc. I'm very curious to hear from folks who have older MD and DAT pres. Do they get the huge improvement in mic preamp performance with an Art or Rolls ?

Seems to me that a recordist who is thinking about upgrading can rethink her/his mic options because that's where the noise limitation is now that the PIP circuit can be worked-around. There's a lot of field testing to be done on the large crop of low noise condenser mics out there. If you go to the usual HiMD accessory stores, you'll see a slew of mics with 22 to 41dB(A) self noise; there should be some lower noise options on their shelves.

Perhaps Sony, Edirol etc. will address/fix the limitations of PIP if we apply some pressure like we did on the .wav conversion issue. Sony is now looking at HiMD as a professional replacement for DAT. I've not studied the history of PIP, but, as I recall, it was a stop-gap solution to cut down on recorder bulk. PIP performs with much lower quality than what most digital recordists know is possible these days. Low noise, inexpensive condenser mics did not exist when PIP was introduced. Rob D.

Hi Clyborne, Greenmachine et al ~

I assume what you are talking about is that there is a compatability issue between the HiMD recorder and an external phantom-power supply, since the recorder is already sending out a phantom voltage, which a phantom-voltage generating power-supply wouldn't normally have to deal with.  Normally a phantom supply would have simply a mic input to look into, without an incoming voltage at that connection. 

Am I following you?

What is PIP, the Sony term, Plug-In-Power?

Thanks for the great discussion, It's cool that you guys with test gear are interested and have the time and tech ability to experiment, and the community spirit to share this with us. Love your attention to detail.  Appreciations extolled!

(The results are also great too!)

Gweeble

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[greenmachine]

That's correct about the phantom conflict. I do not fully understand the nature of the conflcit between most portable phantom power supplies with the HiMD (and other) mic preamp  "Power In Plug" (PIP) circuits. The bad result is a loud fizz and line hum. I've asked on a few lists, but no one has figured out why these two units work and others (even  expensive ones) do not.

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I think a condenser for each channel, connected in series in between could be the solution for blocking DC voltage coming from the MD to enter the phantom power supply and causing conflicts. What do you think?

[clyborne]

Unfortunately, I tried 33-100uf caps to block the PIP voltage but it didn't remove the fizz and line hum from the Denecke PS-2 unit for example. My best guess is the noise is from the switching power supply and the Art and Rolls use higher switching frequencies. The amount of noise may also be affected by the current load from the mic-- another reason we need to run tests on more condenser mics. Understandng what is happening, though, might help in making arguments to Sony/others for a better/more compatible future mic input design. Rob D.

I think a condenser for each channel, connected in series in between could be the solution for blocking DC voltage coming from the MD to enter the phantom power supply and causing conflicts. What do you think?

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