Input impedance

[blackarrow]

Hi,

does anyone know the impedance (k ohms) for both line and mic inputs of the RH10 and RH1 units?

I need it to make a custom battery box with a selectable bass reduction filter.

Thank you.

Marco

[Strungup]

Hi,

does anyone know the impedance (k ohms) for both line and mic inputs of the RH10 and RH1 units?

I need it to make a custom battery box with a selectable bass reduction filter.

Thank you.

Marco

Well the Line out is regulated at 194mv , at an Impedance load of 10k ohms , the Minimum input level for the Mic is about 14mv and line minimum is 49 mv .

I would say the line in is probably about 10 to 15 kohms , while the mic input is somehwere around 1 meg , ( with the sensitivity of the mic in it would very much suggest a Hi impedance input ) use a Varister instead of a Block resistor , on a breadboard ( experiment board )

start with seeting it up for a 50kohm Impedance and work you way up ( sensitivity increases as Impedance increases)

If your input doesnt see a High output but gets the proper impedance you wont have as much noise ( white noise or hiss) if your input sees an impedance that is to low you will get a lot of noise raising the impedance load value and balancing Ouput/Impedance will yeild a good custom design.

Just my two cents.

[blackarrow]

Well the Line out is regulated at 194mv , at an Impedance load of 10k ohms , the Minimum input level for the Mic is about 14mv and line minimum is 49 mv .

I would say the line in is probably about 10 to 15 kohms , while the mic input is somehwere around 1 meg , ( with the sensitivity of the mic in it would very much suggest a Hi impedance input ) use a Varister instead of a Block resistor , on a breadboard ( experiment board )

start with seeting it up for a 50kohm Impedance and work you way up ( sensitivity increases as Impedance increases)

If your input doesnt see a High output but gets the proper impedance you wont have as much noise ( white noise or hiss) if your input sees an impedance that is to low you will get a lot of noise raising the impedance load value and balancing Ouput/Impedance will yeild a good custom design.

Just my two cents.

Thank you for your help.

I also own a sharp mt888 (european version of the mt770) and the unit manual says that it has an impedance of 10k ohms for mic-in and 20k ohms for line-in. With this information is easy to calculate the value of the capacitor necessary to get a well known bass roll-off frequency. Is 1M ohms of impedance for the sony mic-in perhaps too high?

Marco

Edited June 26, 2007 by blackarrow

[Strungup]

That is why I said start with a 50k base , you can work up or down from there , quite easily

But the Sharp mic inputs are quite noisy , I has a Sharp portable , liked the controls and the AUVI amp but the mic input was deplorable (and you just stated why , it has a 10kohm imp load on the input , ) again the higher the impedance the better the signal transfer.

Most good acoustic guitar preamps will have OVER 1Meg impedance and the Piezo crystal elements need that ( soundboard transducers have a Mic level output , unless coupled to a preamp, ) with the Hi imp , The noise floor gets pushed way down away from the signal.

here is a website you might wanna check out

http://www.soundonsound.com/sos/Jan03/arti...nceworkshop.asp

you will notice that they stay in the 600 ohm and speak of impedances of 1 or 2 kohms, but that is dealing with older type standard mic elements , and what your dealing with is condenser mis with circuitry either built in , added to or both . What is brought out is the need to Get impedances to cooperate.

Look at the specs for any mixing board , Behringer , Mackie , Tasco , Soundcraft , You have mics that are 250 ohms load, and mic inputs that are anywhere from 10 k , to 50 k , and in a couple of cases well over that .

then look at the noise levels in each mixer , and again examine the imp load input . there will be a correlation

Here is one of the preamps I have ( and often use as aMic pre , )

http://www.kksound.com/pdf/purepreamp_manual.pdf

you will notice it has a 1Meg input impedance

Edited June 26, 2007 by Guitarfxr

[blackarrow]

Guitarfxr, thank you for these great information.

Marco

[Strungup]

Guitarfxr, thank you for these great information.

Marco

Let me know how the project turns out