michele Posted February 7, 2005 Report Share Posted February 7, 2005 Hi guys,first time on this community ... I'm new at MiniDisc pleasures so I think I'll enjoy it!I'm sure a lot of you can help me with this problem. I got an horrible hum noise when recording my band rehearsal with the Minidisc using the AC adapter. I've read in the manual that is possible to experience this noise if one touch the cable when recording but no one touches anything and even the cables (mic and AC adapter) are separate.On the other side, when using just the power of the battery everything is quiet and wonderful sounding!The MiniDisc is a Sony MZ-RH700 and the mic is a Sound Professional BMC-2 mini binaural.Thanks for the help! Quote Link to comment Share on other sites More sharing options...
Mr Sim Posted February 7, 2005 Report Share Posted February 7, 2005 the problem is AC power itself AC stand for alternating current this means that each of the plugs on the AC (going in to the wall socket) adaptor continually alternates from positive to negative. Though a bit of electromagnetic physics creats its own electric freqency and that is what causes the noise you hear.You said that you were recording your band so you might also want to note that if you are using distortion pedals on any of your guitars and are use AC power you will find that you will be experiencing the same problem. PUT A 9 VOLT INeven though AC adaptors convert to DC the AC frequncy carries through.there is no real way to avoid this problem and continue to use AC power.you'll either have to continue using your battery or find a DC transformer and plug your recorder into a large battery such a 12 volt car battery (MAKE SHURE YOU ARE USING A 12V TO 3V TRANSFORMER). If you are using a PA use your "line in/opt" if you are pluging a guitar straight into you recorder use the "mic plug". Quote Link to comment Share on other sites More sharing options...
A440 Posted February 8, 2005 Report Share Posted February 8, 2005 The battery life on the MDs is pretty remarkable. I regularly record 3-hour shows on Hi-SP with one Duracell and it still reads full, or down one bar, afterward. Since I do use a fresh battery for every show, I change them more often than they run out. A single Duracell will also last all the way through a 1GB, 90-minute PCM recording and then some. Bring two or three batteries to your rehearsal and don't worry about AC. If you want to get fancy about it, get one of the new Energizer 2500 maH chargers and 4 batteries, which will get you through an entire day. Quote Link to comment Share on other sites More sharing options...
michele Posted February 8, 2005 Author Report Share Posted February 8, 2005 Thanks guys, I appreciate your replies. P.S. Mr Sim, excuse me ... I'm such a newbie but ...you mean one can plug an instrument (my bass for example) straight into the MD unit and record it?!!! Quote Link to comment Share on other sites More sharing options...
dex Otaku Posted February 8, 2005 Report Share Posted February 8, 2005 The hum is not just because of the power.The hum is because Sony distribute cheap, unfiltered, unregulated POS power supplies with their equipment. They could spend the extra $0.05 on the parts needed to give perfectly clean DC, but that would up the cost of building the PSUs.there is no real way to avoid this problem and continue to use AC power.This is absolute rot. A properly filtered power supply will put out perfectly flat DC. All you need is a power supply that works properly, and the problem will be solved. The biggest problem with replacing MD and HiMD PSUs is the connector. Concerning battery life, I'll repeat the same story I've given before:I use cheap AA alkalines, no-name batteries that come in boxes of 40 for about $12CAD. In my NH700, using a 1GB HiMD blank, I recorded in excess of 5 hours of audio [from a mic powered by the HiMD] at HiSP, and still had enough battery power to last for at least a couple of days of heavy use for playback.RE: plugging an instrument in; yes, you can plug instruments in and record direct. This will meet mixed results depending on what the instrument is and how much juice its pickup produce, but you can try plugging straight in to the mic or lline-in and see what kind of levels you get. In most cases the mic input will be closer to the impedance of the instrument and will probably work better. If you're coming out of an amp, use the line-in. Quote Link to comment Share on other sites More sharing options...
michele Posted February 8, 2005 Author Report Share Posted February 8, 2005 So I can plug my bass straight into my MZ-NH700 ... fantastic! Just hope it (the MiniDisc) doesn't explode!! I'll try it ASAP ... first I think I have to buy some "1/4 plug jack-to-mini stereo plug" device (?) (well, I don't know how to say it ... I'm italian). As far as the pick-up juice I think (hope) that using the bass in passive mode will work.Other suggestions? You're cool, guys! Quote Link to comment Share on other sites More sharing options...
dex Otaku Posted February 8, 2005 Report Share Posted February 8, 2005 So I can plug my bass straight into my MZ-NH700 ... fantastic! Just hope it (the MiniDisc) doesn't explode!! I'll try it ASAP ... first I think I have to buy some "1/4 plug jack-to-mini stereo plug" device (?) (well, I don't know how to say it ... I'm italian). As far as the pick-up juice I think (hope) that using the bass in passive mode will work.Other suggestions? You're cool, guys! ←Suggestion: if you're going to plug 1/4" cables into your MD or HiMD, use an adapter CABLE, not a plug. Music shops that sell instruments and amps will most likely have these. Reason?Thing of a 1/4" plug on the end of its cable, plugged into an adapter, plugged into your recorder. And think about the weight and strain that puts on your recorder. Quote Link to comment Share on other sites More sharing options...
craftech Posted February 9, 2005 Report Share Posted February 9, 2005 (edited) Dex is 100% correct. Sony used a cheap power supply for these units. I have heard the hum when using AC power myself on my NH900. It varies depending upon the mic you use. My "cheap" mics hum noticeably, but my more expensive mics do not when using AC.With batteries none of the mics are a problem. I also opened the unit after I got it (arguably a bad habit of mine) and I can tell you with confidence that there will be no "previously owned" units in the future available on Ebay that anyone in their right mind will want. Unlike the units (MZ-R50, MZ-R35, etc) of a few years ago, these units are built like most of today's consumer electronics. That is, to self destruct in 1-3 years with moderate use.John Edited February 10, 2005 by craftech Quote Link to comment Share on other sites More sharing options...
craftech Posted February 10, 2005 Report Share Posted February 10, 2005 (edited) Michele,A "regulated" power supply should work much better. Here is one from Radio Shack that comes with various size plugs. One of them will fit your MD. If it doesn't work you have 30 days to return it.http://www.radioshack.com/product.asp?cata...D1662&hp=searchThis one is of higher quality, but larger:http://www.partsexpress.com/pe/showdetl.cf...tnumber=120-536This one is of MUCH higher quality, but you have to assemble it and use another 28volt AC PSU to drive it:http://www.partsexpress.com/pe/showdetl.cf...tnumber=320-216John Edited February 10, 2005 by craftech Quote Link to comment Share on other sites More sharing options...
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