jdisdle

I think there is a greater dynamic range using line in. I would like confirmation of this though. Some battery boxes mentioned on this forum, have a small 9 volt battery that may not be available in the UK. I don't know if they all have a pre-amp either. You will need one with the NH600. Circuit diagrams for mic. pre-amps can be found on the web, at ePanarama.com if you are handy with a soldering iron, I have just built one but as yet have not given it a real test.

I recently bought a MZ NH700. Mainly to use along side a video camera for coach touring holidays. The manual record feature is fine. But there are times when you have to hit record quickly, and AGC can distort the start of the recording. Especially from the mic. input as I found on my now broken MZ R700. These forums have made me think of recording via the line in. Circuits for mic. pre-amps can be found on the web, and I have used one that powers an electret mic. insert from a PP3 9volt battery. The gain is 11db or 23db switched. Recording a train passing slowly through point work causes the video camera AGC to pump. Wrecking the audio. There is no manual rec. on this camera. That`s why I used this as a test. Results from the NH700 using either the pre-amp/line in at 23db, or a powered Sony MS907 plugged to mic. in with AGC at normal, produced a very good recording. This was from about 20ft from the track. Looking at the waveforms in Cool Edit show that although the spikes on both the NH700 recordings are a little off the scale the AGC is not pumping. I used SS 3.2 to download tracks. The technical bit.. Have I wasted my time with the pre-amp? Is the AGC on a minidisk superior to a video camera? I have read that the Line in AGC has a greater dynamic range. Is this true? Your replied will be appreciated.

Have you tried using the Sony 719 in plug in Power mode? It may help. I also suspect the 719 has a sensitivity of –72db. Look for a more sensitive mic. around –68 to –54db should do, or get closer to the speaker.

Quote Huh? How can you afford that? Do you use unpowered dynamic microphones or self-powered electrets? Why do you think the 'plug in power' / bias voltage would make your recordings noisy? Greenmachine. A stereo pot £1.50, one stereo 3.5m jack socket and plug @ 99p each, two small capacitors 40p and make a small metal box. I use self powered electrets. Not expensive maybe more bulky. But better quality. Probably not necessary with the NH700, because there are several choices of input level control. Plug in power is about 2.8volts DC. load resistors are built into the minidisk, and connect directly to the electret capsule. DC flowing through the volume control will cause the track to wear and become noisy. Look at any amplifier circuit, and there will be a DC blocking capacitor at one of the volume control connections.

I am in the UK, and only thinking about the possibilities of the headphone volume control. Mainly for it`s size. Does anyone know if it`s a volume control as in having three connections. And wired across the live side of the mic. it`s centre going to the minidisk in put. I built my own, and used it over the two year life of my Sony MZ R700. You need a capacitor wired from the centre to the minidisk in on both channels to stop the DC/plug in power from making the tracks noisy. The cheap way is an in line variable resistor. Probably acting as a tone control.

You say the buzz occurs when next to these devices. How near is next? Is pick up from the mic. or the minidisk itself? PC`s and Microwaves have fans. Fans are noisy. Is this what you are hearing rather than mains hum? You would have to be within a foot of the TV to pick up buzz. What's so special about recording next to these infernal devices???

TV`s PC`s, Microwaves and all electrical equipment can emit interference when working. Hum can be picked up from mains cables if you are close enough. A mic. in a plastic case, plugged into a Minidisk also with a plastic case is not a good idea in this situation. A metal bodied mic. with proper screening would help. John.