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Gear / Technical Help => Recording Gear => Topic started by: lordbelial on October 17, 2005, 04:11:45 PM

Title: Sony MD N707 Impedance?
Post by: lordbelial on October 17, 2005, 04:11:45 PM: Hi there,

I've an extra MD N707 for stealth recording. I want to loan this unit to a friend of mine who's going to record some little band shows.

I'll loan him the mD unit and the low cost binaural mics from SP, SP-BMC-2, and I have to build a battery box for this purpose.

There's no problem in the building of the battery box, I've been working on the prototype and it works ok, but I need to know the value of the impedance for the line-in and the mic-in imputs of the MD unit. Just because I have to calculte which capacitors should I use to build a fixed roll-off (very bassy venues in my city...)

So, someone knows this data?

I think it goes 4,7 Kohm for the mic in and 47 kohm for the line in, but I want to be sure of this. I want to build a bass rolloff as approximate as I could.

Thanks and Best Regards to everyone.
Title: Re: Sony MD N707 Impedance?
Post by: Weazel on October 17, 2005, 05:59:28 PM: md = mic in =10 kohm line in = 20 kohm

http://burak.relyon.ca/live/battbox.html

calculates it for you
Title: Re: Sony MD N707 Impedance?
Post by: lordbelial on October 18, 2005, 03:11:03 AM: Quote from: Weazel on October 17, 2005, 05:59:28 PM
md = mic in =10 kohm line in = 20 kohm

http://burak.relyon.ca/live/battbox.html

calculates it for you

That impedance is for the SHARP MD models. I really don't know if the values are the same for both vendors, SONY and SHARP, but, if they're not the same values, the capacitors changes A LOT!

For example, for an impedance of 20 Kohm (line in sharp md) we've got a capacitor value of 0.5 uF aprox. But with an impedance of 47 Kohm, the one I guess the Sony MD has got, the capacitor value is about 0.2 uF aprox.

the real problem with impedances goes for higher settings of roll off. If I would like to have a roll off of 195 hz for example...

Line in impedance of 20 Kohm, I would need 40 nF aprox
Line in impedance of 47 Kohm, I would need 17 nF aprox!!!

If my impedance is 47 Kohm, my bass rolloff will be between 65 and 95 Hz if calculated wrong, and not in the 195 Hz range...

BUT! Thanks for the effort! Very very appreciated to see you guys lending me a hand!
Title: Re: Sony MD N707 Impedance?
Post by: Weazel on October 18, 2005, 07:24:30 AM: i think the impedance goes for all md units.
47 kohm is only for DAT recorders i believe

else look on this formum many tapers there with md's

http://forums.minidisc.org/
Title: Re: Sony MD N707 Impedance?
Post by: lordbelial on October 18, 2005, 10:07:26 AM: It seems like i was right, Just taking a look to dynamic audio website...

(http://webpages.charter.net/dlzpayne/images/da120s2.JPG)

You can see...

Sony mic in - 4.7 Kohm
Sony line in - 47 Kohm
Title: Re: Sony MD N707 Impedance?
Post by: Weazel on October 18, 2005, 04:27:38 PM: heh never knew that. so all battery boxxes with selectable rolloff give flase impedance to some recorders exept this one of course.