mmilovan Posted March 19, 2005 Report Share Posted March 19, 2005 Connection of electret , battery powered capsules to HiMD....?Just got from old friend of mine some electret clip-on microphones, these are old, almost vintage mics marked only "ECM 1025, Japan, AO1 (or AOI), impedance 600 Ohm" in metal shield. They are battery powered, with one cell battery LR44W (1.55 V) for each capsule.So, my question is, can I connect these mics to mic-in of my HiMD - I've noticed that metal case from each capsule is connected to "+" battery source, as well as ground of 3.5 jack? Is it safe? Is there some kind of protection, condenser or something in front of mic-in preamp unit of my HiMD?Many thanks. Quote Link to comment Share on other sites More sharing options...
jadeclaw Posted March 20, 2005 Report Share Posted March 20, 2005 I don't see a problem, as the power source of the microphone is isolated from the audio line with an inline capacitor. Quote Link to comment Share on other sites More sharing options...
mmilovan Posted March 22, 2005 Author Report Share Posted March 22, 2005 (edited) So, line-in and mic-in inputs on our HiMD have capacitor right after theirs jacks, right - did I understand it correctly? Edited March 22, 2005 by mmilovan Quote Link to comment Share on other sites More sharing options...
dex Otaku Posted March 22, 2005 Report Share Posted March 22, 2005 Usually the mics themselves are decoupled if they don't require the power. i.e. the capacitor is in the mic itself, between its power supply and the recorder. Quote Link to comment Share on other sites More sharing options...
mmilovan Posted March 22, 2005 Author Report Share Posted March 22, 2005 (edited) Unfortunately, this model of mine are not decoupled, what I discovered by open it. There is only mic electret capsule connected to small battery, cable cord and nothing else. Really don't know if condenser exist in big mono jack of original mic.Is there a way to discover condenser in this mic system? So it is the main reason why I asked this question, no capacitor in my mic clip-on unit I can trace with my limited electrical knowledge.Still, did SONY constructed some system to prevent damage?Big thanks for all yours answers.MilanUsually the mics themselves are decoupled if they don't require the power. i.e. the capacitor is in the mic itself, between its power supply and the recorder.← Edited March 22, 2005 by mmilovan Quote Link to comment Share on other sites More sharing options...
dex Otaku Posted March 22, 2005 Report Share Posted March 22, 2005 You've got me wondering now. On one hand, I've used several different self-powered mics with MDs before without having any problems.On the other hand, looking at the schematics for the NH700, I can't see any sign of any decoupling between the mic power and the actual inputs. The mic power is provided on the ground sleeve from what I can see, and I also don't see decoupling there.I'm not really an electronics expert, though. I can read the diagrams, but it's possible that the preamp inputs are decoupled themselves, and they don't bother showing it on the IC diagrams.In any case, I seriously doubt your mic would blow the input on the recorder. I've used cheap lapel mics from radio shack, expensive lapel mics from Sony's broadcast division, &c. and never had problems. If you're seriously in doubt, try hooking a multimeter to the mic with its power turned on - connections across the tip and sleeve of the connector, with the multimeter set to read low DC voltage. If the bias is getting as far as that connection it should be measurable. Quote Link to comment Share on other sites More sharing options...
mmilovan Posted March 22, 2005 Author Report Share Posted March 22, 2005 Now, I am confused, because there is 1.55V on those mic connector... and "+" is connceted to the ground of the connector... Don't know what to do... You've got me wondering now. On one hand, I've used several different self-powered mics with MDs before without having any problems.On the other hand, looking at the schematics for the NH700, I can't see any sign of any decoupling between the mic power and the actual inputs. The mic power is provided on the ground sleeve from what I can see, and I also don't see decoupling there.I'm not really an electronics expert, though. I can read the diagrams, but it's possible that the preamp inputs are decoupled themselves, and they don't bother showing it on the IC diagrams.In any case, I seriously doubt your mic would blow the input on the recorder. I've used cheap lapel mics from radio shack, expensive lapel mics from Sony's broadcast division, &c. and never had problems. If you're seriously in doubt, try hooking a multimeter to the mic with its power turned on - connections across the tip and sleeve of the connector, with the multimeter set to read low DC voltage. If the bias is getting as far as that connection it should be measurable.← Quote Link to comment Share on other sites More sharing options...
Artstar Posted March 23, 2005 Report Share Posted March 23, 2005 Now, I am confused, because there is 1.55V on those mic connector... and "+" is connceted to the ground of the connector... Don't know what to do...Relax dude ... you're only talking about 1.55V being fed so there's definitely no risk in it at all.Although it is unusual that they would have the + feed going to ground, but that could very well be their idea of decoupling (it is another way to do it, as unusual as it may seem). In which case, just plug it in. I'm 100% sure it will be fine. Don't forget, after all, even Sony sell battery-powered tie-clip mics etc so it's fair to say that they wouldn't be inclined to risk their own product like that. Quote Link to comment Share on other sites More sharing options...
mmilovan Posted March 23, 2005 Author Report Share Posted March 23, 2005 Many thanks you beautiful people... Quote Link to comment Share on other sites More sharing options...
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