Malcolm Stewart

The actual microphone capsule, within the dotted lines on the left of your diagram, requires power to work the FET amplifier. (A FET (Field Effect Transistor) is used because it has the best characteristics for these types of microphone which have a very high impedance - i.e. take very little current.) This power is supplied via the 10kohm load resistor, although I wouldn't describe it as a "load" resistor in this application. The 1 microfarad capacitor stops the DC voltage from the supply upsetting the amplifier (triangle with "Output" as label), and passes the alternating signal from your microphone to the amplifier's input. If you've got little experience in this area, please do try to stop electrostatic voltages from damaging the electrical components when you're assembling things. For example, try not to wear nylon clothing, and if possible have all your components on a conducting metal surface e.g. aluminium foil, on which your forearms can rest. Also, do make sure that your soldering iron is electrically SAFE. I'd advise Googling for "ESD" and "static safe working". e.g. http://en.wikipedia.org/wiki/Electrostatic_sensitive_device http://www.hakko.com/english/static/pages/esd.html Damage from static discharge may be instantaneous, or it may weaken the component, and problems will arise later. Hope I haven't worried you, but a few basic precautions should help you have it working first time.

I'm here because of buying and using several Minidisc recorders over the years. However, last February after some research, I bought a solid state Sony PCM-D50, and can't see myself ever using Minidisc again. Most of my recording is in daylight where the easily seen display of the PCM-D50 is a huge bonus. My two later Minidiscs displays are useless in anything like daylight, and the display on my NH900 has failed. The other advantage is that I no longer have to use Sony's Sonic Stage to upload my files to my PC. Obviously when not using the excellent built-in microphones on the PCM-D50, my techniques are very similar to using Minidisc, so where is the best place to post?

My set-up uses two Yoga lapel style mikes inside wind-reducing Rycote furry covers mounted each side of my baseball cap, and very close to my real ears. From each mike there's a short mono lead to a combiner socket which I clip to my shirt or jacket. The stereo output from this is plugged into an inline socket connected to the ex-earphone lead. To refresh my memory, I've opened the inline socket attached to the lead from the cheap head/earphones, and there's 3 wires. There's a common earth, and colour coded enamelled signal leads. These are only insulated by the heat soluble enamel, hence the compact size. I can plug the gold-plated stereo connector directly into my Minidisc or into the battery box, as preferred. (As this lead is carrying DC to power the mikes, I guess it's more susceptible to noise from minor corrosion or tarnish, and the gold plating is a bonus.) Hope I've made it clear. NOTE: I've now moved from Minidisc to a Sony PCM-D50 solid state recorder. It's bigger than Minidisc, but I can see the screen easily, it's intuitive to use, and since getting it, I've not used my Minidisc recorders at all. There's simply no contest. (It's what the Minidisc interface should have been!)

I'm in the UK, and I've often found that the most cost effective route for buying the slim cable for microphones etc. is to buy cheap iPod style earphones, and then to cannibalise them simply to get the gold plated plugs and slim cable - not available elsewhere. I made a dummy head mic set-up some time ago, using my own head; and going from ordinary plated plugs to gold plated types acquired from earphones dropped the handling noise quite noticeably.

Thanks - I've posted a similar note in the Hi-MD forums.

Went to check my NH900 last night and found that its display is dead. At first I thought it was simply a dead battery, but plugging in my RM-MC40ELK showed that the unit was working apart from the display. Just wondering whether this is a common fault, and whether it's worth asking Sony to repair it. Fortunately, I have other Hi-MD units (MZ-RH10 & MZ-RH1) but the MZ-NH900 was the only one with a display visible in normal daylight, where I tend to do my bird & dummy head recordings. A Google search suggests that there are a few old units still waiting on dealers' shelves, so I think I'll go down that route.

Went to check my MH900 last night and found that its display is dead. At first I thought it was simply a dead battery, but plugging in my RM-MC40ELK showed that the unit was working apart from the display. Just wondering whether this is a common fault, and whether it's worth asking Sony to repair it. Fortunately, I have other Hi-MD units (MZ-RH10 & MZ-RH1) but the MZ-NH900 was the only one with a display visible in half-decent daylight.

You should be OK. The microphones I used in reply #286 (above) were bought as mono lapel mikes, with an omni response. The stereo aspect shouldn't make much difference. I bring my two leads together into a stereo plug where it goes into the battery box. HTH

At last, some time after making my battery box, I've used it "in anger" for the first time, and it didn't disappoint. I went to the NDF in south Birmingham (UK) last weekend, and recorded some of the percussion demos from a seat about 20-30 feet away from the stage. I used a pair of Yoga omnis, with the output of the battery box feeding directly in to the Line input of my RH1. I was in luck. When I checked what I thought was the best track for peak level, I found that it peaked just 0.6dB below max level. I'm very pleased with how the resulting CD sounds on my HiFi system, and am surprised at how clean it is compared to many of my CDs.

Hi Mike, Maplin do a range of affordable microphones, and if you can visit one of their stores, I think you'll find one of them has the lapel clips that you are looking for - albeit in a kit with a microphone. HTH Malcolm Milton Keynes

Congratulations - these things happen! I remember making up a simple microphone extension lead, and checking at every stage; so how did I get left and right reversed! Let's hope your recordings go well.

When I was making my battery box and binaural stereo microphone set-up, I bought cheap stereo earphones (from Maplins) and cannibalised them so that I could get gold plated stereo plugs and lightweight cable at a sensible price. With the voltage supplied to the mike capsules, the low noise gold plated connection made a big difference in handling noise. The screening may not be good enough for use in a building where mains fields exist, but in the countryside it's fine, and environmental noise from distant motorway traffic, aeroplanes, and helicopters is my main problem.

For fishstyc I was going to make the same point. Occasionally, the noise level has been so low that the automatic Track marker has kicked in. Can't remember which Hi-MD recorder I was using. (On the contrary I have found it quite difficult doing wild-life recordings of, say, birds, very difficult without picking up distant road noise, aeroplanes etc.)

Thanks for the clarification. I've never used any of the equalisers so completely forgot what impact they could have on the ear-phone output. As for me, I'm now asymmetrically deaf so feed the output of my MD players into a SoundProfessionals headbanger amplifier with an attenuator lowering the input of the left channel. Works quite well (apart from the increase in bulk and cabling!), and I can probably hear better stereo via 'phones than naturally with distorting hearing aid. Years ago, my hearing was good enough for me to sit on a HiFi listening panel! Not anymore. (And it's hereditary, not induced by rock concerts etc.)

I've knocked up a battery box (as per this thread) and using the same small omni microphones, all I've noticed is how clean the recordings are, albeit at a lower level than via the mic input, naturally. (RH-10 and RH-1) Connecting the battery box output to the mic-input is OK. The 9V only goes to the mics themselves, and the output is isolated. There's no amplification in the battery box. Whether the electronics in the mic gives a little more gain with the higher voltage, I've no idea. Extra bass often comes from having the mic closer to the sound source - something which a higher dynamic range may encourage. I suggest you just get the parts and give it a go. I'm sure you won't be disappointed. If you then find that you are concerned about the frequency response, there are plenty of tools available for dealing with that when you've uploaded to your PC.

Would you like to elaborate a bit on why you consider a proper <Line Out> to be important. The headphone output isn't that far away, or am I making some wrong assumptions? (I've found the OLED display on my RH10 quite useless in normal daylight, but as you indicate, quite good for playback.) Cheers,

I'm in the UK and use Yoga mics (electret omni tiepin types at about £10 each - a pair for dummy head stereo) from Maplins for most of my recordings. I haven't noticed any noise problems so far, even when I raise the level on quiet recordings. (NH900 & RH10 recorders) I'm not claiming that Yoga are in the same league as the professional kit, but I'm sure they'll be fine for starters.

Very interesting report - did the musicians believe that your kit would do them justice?!! Could this lack of bass be due to the mic being a directional type. Omnis normally are a bit better for deep bass, I think. It's good to hear that you like the mic as I'm thinking I might get one for use with my camcorder.

I'm mainly in to live recording of birdsong, some church bells, dummy head stereo, and some minor music events. I have the NH900 (for use in bright daylight, display is useless in dim lighting), the RH10 - lovely display in the dark (but bought to safeguard the playing of my HiMD discs should the NH900 fail when it looked as though Sony were dumping Minidisc) and now the RH1. Along the line I bought the RM-MC40ELK direct from the US/Japan (only to find it on sale, separately, in the UK and at much the same price!). I like the RH1, but that uses the new LiIon battery (and there's a separate thread on this). I do struggle at times remembering how to get the desired Menu option on the machine/RM I'm using at the time, and then there's the problem that not all RMs deliver a full featured range of options. All in all, I consider that Sony's marketing is superb and somewhat cynical. They've sold me 3 HiMD machines whereas if the decent features were all in one machine, I would have bought two at the most.

I'm in the UK and don't normally think of buying from "too cheap to believe" ebay sources, but the price differential between Sony Spares in the UK (£28 + postage) and the ~£10 (inc postage) from China seemed to be worth looking at. I ordered mine in two lots. 1st lot of 2 cells arrived within 7 days, and the 2nd. lot of 1 cell within 8 days. The cells carry a recyclable label (not prsent on the original in my RH1 unit), and came without the plastic case. Otherwise they charged OK, and seem to have plenty of life in them. (I'll report here if they turn out to be junk.) So I've ended up with 3 spare cells for around what I would have spent on 1 from Sony UK, plus a few Chinese postage stamps.

Thanks for your comments. Haven't seen an NH-1 since before I bought my NH-900, but I'm afraid you've now got me confused in the sentence above.

Well as you can see from my signature, I bought my RH1 yesterday, and from my local Sony Centre in Central Milton Keynes. They may have the display model left. As others have said, it's certainly aimed more at recording on the fly. Shortly after opening my patio door this am, I thought I heard a woodpecker hammering away in the trees. I'd already set it to manual recording, and I now have a clear recording of my "woodpecker" at work. (Will have to check whether I'm correct.) It's great to be able to record straight off, and to have a dated recording. Very useful for wildlife etc. My black model isn't quite the same as that illustrated in the posted review. The markings for the -12db are now in roughly the correct position. Can't say the spectrum analyser helps much, but some may find it of help. I do like seeing levels on playback - just as my old Panasonic MD units performed. I expected to be able to use the same drivers as for my RH10 & NH900 - not so, on my Win98SE machine. I had to go through loading Sonicstage 3.4, and on my machine (with the latest McAfee anti-virus in use) that took an absolute age, and in places where Sony hadn't expected any delay, I thought my PC had frozen. Anyway, eventually it was all up and working, and I haven't lost any library tracks. Headphone Output levels - these are now more or less the same for European and other models - 4.5mw and 5mw. Packaging... I simply couldn't believe how heavy the box was! (>1.2kg for a 110g unit.) I fully expected to find an old fashioned iron and copper mains adapter, but no, the weight was from the separate copies of the instruction manual in each of 6 languages. Is this really environmentally friendly? Even if the paper is recycled? Must get out and capture some more wildlife.

I've done it on my RH10, and it's quite straightforward. All the items are supplied, and the instructions are clear. No idea whether it made any difference as I did it before doing any recordings. (If the ferrite cores really were "tiny" I guess they'd be inside the RH1's case! They're actually quite sizeable, but at least on the RH10, aren't needed when doing field recording with electret microphones.)

Beware!! I don't know where SoundProfessionals got their detailed spec sheet from, but in key areas such as battery type(s!!!), it doesn't agree with what I downloaded from this site for the RH1. My understanding is that the RH1 takes ONLY a Lithium rechargeable cell (3.7V LIP-4WM), and that it doesn't permit an "AA" cell outrider. My local Sony Centre had a black RH1 in stock last week but no (spare) batteries for it. I'm still trying to source LIP-4WMs at a sensible price in the UK. A year ago they were around £35. I've seen them at around £10 (incl postage) via ebay from China, but obviously I'd prefer to find them in the UK.

I'd always tend to record FM radio at a fixed level, set high but so that distortion or clipping doesn't occur, but I think it could depend on how you intend to listen to the result. If you want background music and the source level is varying, using ACG might just give you a more useful result. I do find the AGC on Sony's Minidisc recorders is quite powerful, and noise pumping quickly becomes obvious. Equally, I've found that recording manually and a little down from max level, and then using the "Amplify" function in Audacity, I can bring levels up after the recording session, without (too) obviously raising the noise level. Recently I've recorded some recitals where the spoken introduction between pieces was at a very low level (no PA amplification versus amplified instruments), and 20-30dB gain in Audacity was useful to make the intros audible! (Here, quality definitely wasn't an issue!!) HTH