Messages

1

Reel to Reel Tape Machines / Re: Nagra IV-S and Sennheiser MKH 110

« on: November 03, 2008, 05:24:48 AM »

Here's some battery box plans you might compare with yours.
http://taperssection.com/index.php/topic,72994.0.html

cheers : )

2

Reel to Reel Tape Machines / Re: Nagra IV-S and Sennheiser MKH 110

« on: November 03, 2008, 05:24:05 AM »

Really interesting mic you have bibio. I googled it when I saw your post. That thing must really get down there! I have to wonder if the 110 can be powered with  8v or must be powered with 8v. I have some Sennheissers and Audio Technicas that can be powered with 6v but they can also be powered with 48v too. If this is the case with your MKH's you shouldn't have to block the power coming from your Nagra. Just a thought.
Another thing you might try is to run the battery box into the line in rather than the mic in. I do that all the time with the flash recorders I use.

I'm not really planning on using it as an infrasonic mic, but maybe one day... besides, I can't imagine the nagra I have will extend that low. Nagra made the IV-SJ for jobs like that, which was indeed the recorder used with the MKH 110 by recordists needing the infrasonic range.

The manual for the MKH 110 says it can run on 8v +/-1v, so I should stick to that.

If I run into the line, how will I get the gain? The box I have built is only a power supply.

3

Reel to Reel Tape Machines / Re: Nagra IV-S and Sennheiser MKH 110

« on: November 03, 2008, 05:20:53 AM »

Others please jump in here, but wouldn't you just need to increase the size of the series DC blocking capacitor to extend the low frequency response?
Any capacitor by definition will block the DC, but the larger it is the lower the roll off point will be. It represents a 6dB per octave filter with the termination impedance of the microphone input.

I've been told the same thing, so yes, I should try that. Another issue that I've just realised is that I'm planning on using the dynamic mic settings on the nagra, one is 50 ohms and the other 200 ohms. The MKH 110 manual states that an amplifier can be used whose impedance is >2kohms. So I need to raise the impedance considerably, I have been told this will affect the frequency response of the mic.

Any comments on this folks?

4

Reel to Reel Tape Machines / Nagra IV-S and Sennheiser MKH 110

« on: November 02, 2008, 11:34:06 AM »

I recently bought the MKH 110 and have had to build a special battery box to power the mic as it runs on 8v. Part of the circuit has a 220N capacitor on the audio out to isolate the DC on the cable from the mic pre. However, this causes a low frequency roll off that starts too high making the mic bass-light, and in its prime, it is anything but with a frequency response going down to 1Hz. It also causes a pinch/boost at 250Hz.

If I take the 220N out of the circuit, it stops the bass roll off but now there is a voltage going to the amp. I haven't tested this with my nagra as it is too precious. I tested the circuit, sans 220N, with my behringer desk which seemed fine. I've been told that if the amp contains a DC blocking capacitor there will be no need for the 220N.

Does anybody know if the Nagra IV-S mic pre contains a DC blocking capacitor? Also, if it doesn't, will my circuit cause any harm if I don't isolate the DC voltage from the amp?

There is also a possibility that the mic's extended low end may cause saturation if there is no roll off at all as those low infra-sonic frequencies may cause problems, so perhaps a capacitor will be needed but does anyone know what capacitor will help with the roll off?

Please bear in mind that I know nothing about electronics, so be gentle with me!