Zoom Gear & Home Recording Forum

Introduction

Most of this has been posted here and there before, but I thought a summary might now be handy.

Should I be reading this?

Much of the following advice assumes you will download your H2 recordings to a PC for post-processing. If you are using it simply to record and play back via its headphone/line output, you may find some of the built in functions more worthwhile. ISome advice on settings is also perhaps more applicable to wave format recordings than mp3 recordings, where the processing that goes on to compress and decompress the audio can introduce other considerations in some circumstances.

Overview

The Zoom H2 is the audio equivalent of a point and shoot digital camera. Such cameras normally have provision for digital zoom and colour effects like black-and-white or sepia, but nobody in their right mind uses that stuff if they have access to Photoshop software or the like. It's much better to process copies of the images in the PC than irrevocably in the camera. Likewise, the H2 has digital level control (functional equivalent of digital zoom) and limiters etc (comparable with sepia effects) which are best avoided if you will have the opportunity later to apply such changes to the recording in your PC at your leisure and non-destructively.

The key feature of the H2 is its twin stereo mics. Consider what you would have to take out with you as an alternative - two stereo mics, mixer with four mic preamps, multichannel recorder or a laptop with firewire audio interface, and associated cables. Make the most of the built in mics and you'll get the most from the H2.

Analog recording level control

This is the switch on the side marked H M L (High, Medium, Low).

Tests using wave format recordings have shown that there is no audible difference between the H and M settings, if you raise the level of a low-level recording you made using the M setting by 10dB in the PC later on. Noise levels are identical. The H setting risks overloading and distortion in the analog preamp if there is an unexpected loud event. Therefore, you may find that you only ever need to use the M and L settings to record from the built in mics - forget about H. However, the L setting introduces about 6dB more noise than the M setting and should only be used if you are convinced that overload will occur with the M setting. M seems to cover most situations apart from loud amplified music. With that advice in mind, do some tests of your own and see what works best for you.

Digital recording level control

The record level control (0 - 127) should always be set to 100. This control simply changes the level in the digital domain and you can do that in the PC afterwards just as effectively - and at that point you'll know what the recorded levels were. Raising the recording level in the H2 above 100 risks digital overloads unnecessarily. Lowering the level in the H2 below 100 will not prevent analog overloads - all you will do will be to reduce the level of the already-distorted audio. (If recording very loud amplified music, L100 might result in both analog and digital overload - you might find that using a setting below 100 in that kind of situation could give a better result by at least removing the digital distortion component, though you'd still hear quieter analog distortion - I'd suggest doing your own tests).

Rec Mode settings

Tests have been unable to show any useful outcome from using 24 bit wave recording mode settings in the H2. The analog stage noise levels, while perfectly acceptable for making recordings from the built in mics and from line-in sources, are above the 16 bit noise floor. Using 24 bits to record significantly increases file sizes for no proven benefit, with this recorder.

Using higher than 44.1kHz settings can provide extended frequency response but whether the resulting larger file sizes are worth the benefits should be considered. (However, there is evidence that the chipset in the H2 is optimised for 48kHz recording - you might want to try that yourself and judge the benefits).

High frequency cutoff at about 16kHz in mp3 recordings even at 320kbps can be seen in tests but this may not be a significant problem with most sound sources. If space on the memory card is not a problem, don't use mp3 settings - you can easily convert from wave format to mp3 in your PC later.

Making long recordings (over 2Gb)

The file size limit on the H2 is about 2Gb - how long a recording that provides depends on the recording format you are using. There's some guidance at http://www.zoom.co.jp/english/products/h2/sd.html which might help you work out what's you'd get into 2Gb. When the H2 reaches that limit, it will think for a while - maybe around 20 seconds - then it will create a new file (or files, in 4tr surround mode) and carry on. You'll lose that 20 seconds of audio. If you really need very long recording times without stopping, and you don't need 4tr surround, consider using mp3 format at the higher bitrate settings, which should avoid the whole problem.

AGC/Comp settings

AGC, limiters and compressors in the H2 all appear to work in the digital domain. They will not help in avoiding analog clipping in the preamp. It is recommended not to use them in the H2 as the mangling of the sound that results cannot be undone afterwards. If you want a compressed or limited sound, use one of the many built in or freeware effects in your PC audio editing software after recording, and save the result as a copy, thus preserving the integrity of the original recording in case you change your mind later. To even out the level of spoken word recordings in your PC, try "Levelator" freeware software.

Using the built in mics

Be aware that you can't use the 4 channel surround mode for mp3 recording, but the H2 will automatically switch in and out of wave format for 4 channel if you normally have mp3 selected for recording in other modes.

If you have space on the memory card, you might consider using the 4 channel surround recording mode in preference to the 2 channel surround mode, as it permits you complete freedom afterwards to remix the front and rear mic files. That gives you remarkable flexibility in creating the sound image.

Using external mics

Noise levels when using external mics have been found by most users to be higher than expected. If you have a minidisc recorder, you'll probably get better results from that. If you are thinking of buying an external mic to go with the H2, take the H2 to the store to test compatibility. And expect to pay more than you paid for the H2!

Using line level sources

The sensitivity of the line input socket seems slightly higher than it should be. You cannot control it from the H2 in the analogue domain. If the device you have connected to the H2 has no means of controlling the level it outputs from its line-out socket, see if the level from any headphone socket it may have can be controlled, and connect that to the H2 line in - you will probably get perfectly good results that way. As a line-in recorder the H2 seems at least as good as a minidisc recorder, and of course subsequent file transfer is much simpler and quicker.

Auto-record

Be aware that this is a one-shot process - once the H2 has started recording and then stopped, it will not start again. It's basically intended to allow a musician wanting to record their own performance to set up the H2, get in position at their instrument, and then have the H2 record from the start of the performance.

Monitoring

Monitoring of the built-in mics or external inputs can be switched on permanently in the menu, enabling you to judge the effect of changing menu options before recording - normally you cannot enter the menus when in record-pause mode. You could use the H2 as a mic outputting to another recording device in this mode. But monitoring will continue during playback. This could be a nuisance sometimes, or handy if you want to hear what's happening around you while listening on headphones. Note that if you connect to an amp and speakers while monitoring is on, you could get feedback.

L/R Posi

If you don't have that option you need to download and install the latest firmware from http://www.zoom.co.jp/english/download/software/h2.php - basically it allows you to set the left/right soundscape correctly when you record with the rear mics facing the performers.

File operations

Almost everything in the file menu would be more quickly accomplished in the PC later but if you are on location and you want to delete unwanted files, you'll be glad to be able to do this in the H2 itself. Normalising and converting to mp3 in the H2 seems to take a long time - if you can, do that in the PC.

Playback

Playback operations are pretty straightforward - the only unexpected thing is that to play back a four-channel file, you need to have the four channel surround mic pattern selected on the front of the recorder - then it will access the dedicated four-channel folder for playback as well as recording. The way the fast-forward and rewind keys operate depends on the file type in use and whether you are paused or actually playing - investigate what happens if you hold down the buttons.

Transferring files to the PC

The USB port on the H2 is USB2 but "full speed" - slow! - rather than "high speed", which is true USB2. You will probably get a quicker transfer by removing the memory card from the H2 and putting it into a USB2 high-speed card reader instead.

USB Audio interface

I've found that the H2 doesn't work well as an audio interface if connected via a USB hub. If you have problems, try connecting it direct to your PC.

Memory cards

The manual says that cards up to 4Gb can be used but cards of 8Gb are now listed as working with the H2 on their site at http://www.zoom.co.jp/english/products/h2/index.php - keep an eye on that site for updates. But bear in mind that the maximum filesize the H2 can record without a break is 2Gb. You may also need an SDHC compatible card reader for your PC if you use cards of 4Gb or more.

Be aware that the H2 settings are stored on the memory card and will be lost if you format the card, or use a new card with the H2. You will then need to skim through the menus setting things back the way you like them, although if you accept most of the advice above you will find the default values are about right. You can copy the settings from the sys folder on the card if you want a backup.

Enjoy your H2!

If your expectations are realistic, you'll find the H2 is a great little device for the things that it's good at - chiefly as a surround mic for the price of a stereo mic, with a built-in recorder thrown in free. Please do add your own hints and tips to this thread - and correct me if you think I'm wrong on any point!

For those technically inclined, here are the initial measurements on my H2, 'out of the box', when it arrived today...

First - the Line Input.

The Line Input impedance is approximately 14K ohms. The inputs saturate at a voltage of about 0.57 V RMS, or -2.7dBu, -2.7dBm, -5dBV

It is interesting that the line input overloads at exactly the same point as when the Digital gain setting is set to 100 and 0dB displays on the VU display. My guess is that line-in goes straight into the AD converter. When I buzz the circuitry I will be able to check this out.

The spectra when my H2 is fed with a 404 Hz sine wave from a function generator (3% distortion, so you can see the harmonics at 808Hz, 1212Hz, and etc) can be found at URLs
http://TrevorMarshall.com/temp/Line_441_16_0dB_100.gif and
http://TrevorMarshall.com/temp/Line_96_24_0db_100.gif

I only have SoundForge to do the FFT, so it is not as pretty as some of the other FFTs scattered around the net, but it will do.

I am surprised how clean the recorded signal is. I will try two-tone and other more complex tests later, after I get rid of the power supply noise.


Next - the External MIC input - High Sensitivity (H) selected

The input impedance is 1800 ohms. It is intended for low impedance microphones. The input impedance did not change significantly when I switched the MIC Power on or off.

I plugged in an ARCHOS stereo electret lapel microphone (my favorite lapel) and it was moving the VU meter to almost the same levels as the internal microphones. An old Sony stereo lapel mic was the same level as the internal microphones at about 12 inches. The H2 seems to like the high-output recorder-powered electret condenser microphones.

When switched to H, the ext mic input overloads at 12 mV RMS, and, surprisingly, the top half of the sinusoid clips well before the bottom half. H2 engineers need to trim their analog design a little. Asymmetric clipping is a no-no for professional, or even prosumer, applications.

I advanced the digital gain to 104 so that the ext mic input and the digital indicator bar-graph reached clipping and 0dB simultaneously. The spectrum can be found at URL
http://TrevorMarshall.com/temp/EXTMIC_96_24_0db_104.gif

The dynamic range is excellent, with less sampling artifacts (above 20KHz) than the Line input exhibited.

The trick to getting good performance out of the external microphone input is to recognize the low impedance and make sure you use a high output microphone (my lapel mics were rated at about -35dB re 1V/Pa. The Rode SVM is rated at -44dB re 1V/Pa, probably accounting for its lower signal to noise ratio when used with this input. I hesitate to suggest this, but the external microphone input seemed to be well matched to Karaoke with my AKG MB4000C microphones

Here is the spectrum with the EXT MIC socket, with the microphone sensitivity switch set to M and LO-cut enabled
http://TrevorMarshall.com/temp/EXTMIC_9 ... db_104.gif

And here it is with the mic sensitivity switched to L and LO-cut.
0dB input was 0.23 V RMS, -10.5 dBu, -10.5 dBm, -12.8 dBV
http://TrevorMarshall.com/temp/EXTMIC_9 ... db_100.gif

OK. I am very happy at this point. I can use this machine. It is very nice indeed. I will take a look at the innards and the power supply noise when I get some spare time, maybe later this week. My Firmware is 1.10

Trouble is, if I connect the Rode SVM to the mic input socket with the mic's power off and record on H 100, the level meter on subsequent playback in Audition is sitting around the -50dB mark. Turn the mic on and that -50dB noise floor is still there. Plug in a plugin power lavalier (make unknown!), there's still the same noise floor. Plug in an unterminated lead and the noise is there, short it out and the noise is there. I don't see how you are getting excellent dynamic range results with that noise going on, as even if I found a mic with a big enough output to deflect the meters to maximum the noise floor would still be at -50dB. When the input is on "L" you might have a fighting chance of working with an acceptable noise floor (meters around -75dB) but then the mic would have to be outputting at close to line level to get the meters towards peak. I'm mystified.

Peter,
I have now posted all 3 FFTs from L, M, and H settings for the EXT MIC on my H2. It is possible that I have a later H2 version, my S/N is around 24000, but I am seeing excellent signal to noise ratios on any of L, M, or H, if you can drive the input to 0dB on the bar-graph, with the digital gain at 100.

I am normalizing at the input, rather than the output, as you have done, and am getting results which are in line with what I would expect from this class of recorder.

I might add that the performance of the analog circuits, once they go into overload, is woeful, and to be avoided at all cost. There is bad design in the saturation region. I also agree with your observations about the Limiters. Haven't figured out what use they might be, as everything is better done in post-production, IMO.

ps: Have you tried switching your H2 to 'monitor' in the menus? That way the headphones and VU meters are on all the time, and it is easier to adjust stuff..

Well, I do wonder whether they've made a modification... my S/N is circa 14000.

Here is a short 44.1/16 wave file created by connecting an unterminated lead to the mic input on H, 100, no low cut or anything like that. Do you hear that hiss on yours? I realise that an unterminated lead isn't usually a good way to test, but this hiss is more or less what I get under any circumstances.

http://www.fileden.com/files/2007/9/22/ ... TE-000.wav

Peter,
Your noise floor is similar to mine. But the peak signal is way above this. You need to be driving up towards 0dB to get a good signal to noise ratio.

SoundForge gives the RMS power in your sample at -68 dB. The key is to drive that input to an RMS power of 0dB

-68dB is a good low level for RMS noise. And once it is A-weighted it will drop even lower.

Peter, as a datapoint, I applied a filter (using SoundForge) which was roughly A-weighted, from the graphs at
http://en.wikipedia.org/wiki/A-weighting

I compared the RMS power (reported by SoundForge) in 20 secs of unequalized unterminated noise sample (96/24) and then the same statistic after applying the filter roughly equivalent to an A-curve.
On the H setting I got -66dB -> -72dB
On the M setting -66dB -> -81dB
On the L setting -65dB -> -90dB

The difference is because a lot of the noise floor in the H2 is at low frequencies, where it can't be heard as clearly. You can clearly see the change in the weighted data as the gain of the input stage is changed.

...and you'll be listening to any input or mic signal even during playback of a previous recording. :-/

Just one of the many indiosyncracies of the H2 and H4.

I've tried to measure the s/n ratios of both Zooms purely in the analog domain by measuring what comes out of the line output for any given input signal (or a terminated input with no signal appplied). While this shows a respectable 80+ dB from the H4's line input to the line output, I wasn't able to do the same measurement with the H2 because its line output has a consistent noise level of around -40 dBV at output level "100".

Ralf

Thanks, Trevor, at least my Audition and your Sound Forge agree on the RMS value of that noise sample, and Zoom are not going to besieged by people wanting their hardware upgraded to match the latest version! Clearly your hardware is the same as mine.

Well, I'll just repeat that if you are familiar with Sony's MD recorders, you won't like the H2 mic input. To my mind, it's best to judge subjective signal to noise performance with very little signal. I can record a quietly ticking clock with the Rode SVM mic into a Sony HiMD recorder and hear no noticeable background noise unless I greatly amplify the recording. I can do the same with the H2's built in mics. But connecting the SVM (or any other mics I have here which will directly connect) to the H2 results in a recording where the ticking clock is barely audible beneath the H2 mic input noise. For loud rock music, you might get away with it, but for anything less, it's going to be a disappointment.

This file - http://www.fileden.com/files/2007/9/22/ ... 20test.wav - is of the quietly ticking clock, amplified considerably after recording, though you'll still need headphones to hear it properly. Before going into the quiet room with the clock, I recorded a 440Hz tone on each equipment combination, and normalised the recordings using that recorded tone later. Therefore the actual sound of the clock should be at about the same level in each case. What the recording demonstrates is the ability of the recording equipment to resolve the sound of the clock above the self-noise of the equipment - or not. The clock was separated from the mic by the length of a sheet of A4 paper in each case.

First you hear the Rode SVM mic with the Sony RH-1 Hi-MD recorder. Second, the H2 in standalone mode (rear mics) - the noise is subjectively louder and is of a different quality but the clock can still clearly be heard. Lastly, the Rode SVM into the H2 mic input (on H) - the clock is barely audible above the hiss.

This is a severe test, and the Rode/RH-1 combination could set you back the price of almost three H2's, but I'm afraid that minidisc is bound to be what all handheld recorders get compared with, and it's what people with existing plugin powered stereo mics have probably been using - to my mind it's the format they are often seeking to replace.

Good observation, certainly true in my case. I've got an H-4, Edirol R-09 and a RH-1. When I want the best results from my PIP mics, I take the RH-1 along. R-09 sits in the fiddle case (better to have something than nothing at all times), the H-2 would serve that purpose as well from what I am reading.

Nice test Ozpeter ! I just repeated it with my MZ-NH700 and the microphone modules sold by Greenmachine. I added one test based on a tip by him ... using the MZ-NH700 as pre-amp for the line-in of the H2.
However based on my ears I can't choose between a MD recording and MD as pre-amp for the H2. Both recordings sound better than the greenmachine modules on the mic-in of the H2 or the internal mics (rear) recording of the H2.

Just checking, you plugged the mic into the MZ and ran line out from the MZ into the H2?

Peter,
Unfortunately I cannot tell anything about the noise floors after they have been normalized. How many dB quieter is the HiMD? Can you please give us a 20 second snippet of its noise floor?

Is the 'PAD' button on your SVM on or off?

There is no doubt that the input of the H2 is not sensitive enough to pick up quiet noises from your SVM, the question is whether the HiMD will overload when you apply the maximum sound pressure level that the SVM will take: 130dB. The data sheet says the SVM has a dynamic range of 115 dBA and that will be stretching the dynamic range of any input I am sure the H2 will overload too. Getting maximum dynamic range from a microphone is always a juggling act.

The H2 is clearly not suitable for the out put of SVM, at low signal levels, but it does match my lapel electrets, which will keep me happy If I need to record low level sounds, I have a tiny preamp I built into an Altoids tin which has a very low noise input, much lower than the H2, and a built-in analog limiter:) But that's cheating, I know

Could you be convinced to provide the schematic? I'd gladly host it.

Ralf

Yes, put the minidisc on rec-pause. Plug the mic in the minidisc player and connect the headphone connection to the H2, volume highest. In this case I have put the minidisc on manual recording level 20/30 and mic sens low. Make the connection to the line-in of the H2. It is a creative idea from 'greenmachine' ... I don't know how it compares to a 'real' pre-amp.

Nice idea! I just happen to have an MZ-N707 as well as a Nady CM-2S.

I bought the H2 (and the minidisc and mic a while ago) to record my own gigs. Mostly folk or music that's similar. Setup with a "preamp" nearby would be a pain but doable.

I wonder if that would offer better sound than the internal mics of the H2. Less portable but sometimes that's not the end of the world.

Of course there are better mics than the Nady CM-2S so I wonder if it's worth the effort. Any opinions?

I do own some other mics, including some decent small diaphragm condensers. But they require phantom power. I also own 2 Studio Projects preamps, I could get a Y cable and send them to the line in of the H2 - but then it's starting to get crazy - hooking all that up to the small H2. But hey, it might just be the way to go! (there was a time when I was bringing an Edirol UA-25 and a laptop with those mics and calling that portable)

Which mics would you audophile/techies go to the trouble using with external preamps instead of the internal mics of the H2?

I'm using my H2 (and H4) with Beringer B2's and a stereo set of small diaphragm condensers connected through a small Beringer Eurorack mixer, all fed through a 12 V to 230 V inverter in the rear of my car for recording soundscapes.

Results are far better than those with the built-in microphones. Especially with soundscapes, the larger mic separation makes for a much wider, more spacious stereo image.

Ralf