Topic: fixing the impedance

[udovdh]

Hello,

What is the best way to fix the impedance that my mics see to say 47K? (independent from the recorder line in impedance)
On micbuilders I read about doing this by using a transistor on the batterybox and put it in between the signal path.
This sounds interesting but selection of the transistor for noise and distortion specs is not my kind of art.
Do people here have ideas or suggestions for fixing the impedance?

Udo

[udovdh]

The best way is to use what is called a buffer amp. What is the issue for your mics? a matching transformer might be a simpler option for you but your looking at $200 for a pair of good transformers Poolyconditioned has some transformers lying around from the AT preamps he is using to make battery boxes out of you might want to talk to him.

Stuff needs to be (very) small and not too expensive. Maybe even lo-tech, as it is currently. So it is either an opamp or a transistor?
Issue is slightly different tonal response of the mic plus bbox combo, impedance closer to manufacturers recommended specs thus guaranteeed performance, etc

[udovdh]

What mics do you have? lets see if I can help you also what recorder are you using?

The best way is to use what is called a buffer amp. What is the issue for your mics? a matching transformer might be a simpler option for you but your looking at $200 for a pair of good transformers Poolyconditioned has some transformers lying around from the AT preamps he is using to make battery boxes out of you might want to talk to him.

Stuff needs to be (very) small and not too expensive. Maybe even lo-tech, as it is currently. So it is either an opamp or a transistor?
Issue is slightly different tonal response of the mic plus bbox combo, impedance closer to manufacturers recommended specs thus guaranteeed performance, etc

Recorder can be the MT (5K3 line in impedance? was 47K at the Sony).
Mics are the Sennheisers in the mic area. They need 15K terminating impedance at least.
They work OK with less.
Current setup is the ultra-simple 2-wire batterybox which has given me solid performance.
In what way does this matter?

[udovdh]

In short: I do not need amplification.
So I do not need a pre-amp.
Stuff nees to be (very) small.
A buffering op-amp might fix stuff?
Suggestions?

[udovdh]

Yah tell me what mics you have and what recorder you are using and what you want to record loud music or speech.
A buffer amp is only one solution even if I build you a buffer amp it will be about the same size as my preamp you still need to power it with a 9 volt battery.

Mostly louder stuff.
MM-HLSC-1 and a MT.
Bbox with 9V battery generally works well.
Solution needs to be small as can be. 1 dual opamp with some resistors?

[udovdh]

So if what you have works well what is the problem you just need a bit more boost from time to time? I do not understand the impedance issue that you say you have. Why do you feel you have an impedance issue? with your set up as it is now

I don't need a boost. The recorder can do that, or I play with teh bbox resistors.
The mic needs to see a minimum impedance.
Currently it sees a lower impedance.
That needs to be fixed for optimal performance.

[Javier Cinakowski]

I have the Sennheiser MKE40's (mic madness) and Church's STC9000 Preamp.  The Church preamp has 10K input imdenance. The Senns supposedly need 15K impedance or greater.  I am concerned as well that I am not getting the best performance for my mics.  Also the line input on the Hi-MDs are 20K.  The output on the preamp is 10K.  I am concerned that is a problem too.   Do I need to get a new preamp?  Should I get a preamp that has 15K input and 20out?  While I am at it should get my mics converted to 3-wire?  (mke40's and mke2's)

[udovdh]

The slightly lower impedance is not a big issue but the performance will not be as designed by the manufacturer.

[Javier Cinakowski]

I was just concerned that I am not matching impedance and the quaility could be better.  I have not had any problems, but just want to get it right. 

[Javier Cinakowski]

Why would I be better with a 3-wire?  Im not sure I am convinced there are benefits to three-wire? 

Would the 3 wire be good for both the mke40's and mke2's?  I would make the upgrade if it would improve performance in any way.

I ripped the belt-clip of of my stc-9000 so it is not in mint condition.  I am assuming that you would not want to take back a non-mint unit.  Or can you just add the 3-wire to my current preamp?

[Javier Cinakowski]

My microphones have not distorted.  I have recorded very loud concerts.  I would however like more low-end in my recordings, but I think the lack of bass is from the microphones frequency responce(roll-off at 100hz ) and not a 2 wire problem.   Microphone Madness claims these mics to have 138 max SPL with 3v PIP.

[udovdh]

Distorted bass at 4 feet of the stacks?

[Javier Cinakowski]

Distorted bass at 4 feet of the stacks?

Who/What are you talking about?

. Low end response is the hardest part of making a cardioid mic, if you want put your self on the church audio mic loner thread for my cardioid mic you will then have the opportunity to hear a good quality cardioid mic. Not that your mics suck but I think the bottom end of my mics is very good. If you listen to the sample recording I have made on a real stereo there is very good bottom end in the recording. I have not heard any recordings from the mics you have yet I am sure they are great, It would be impossible for me to say if my mics are better I guess that’s why I put them on the loaner program so others could hear them and compare them to what they have.
 

Chris Church

My microphones have not distorted.  I have recorded very loud concerts.  I would however like more low-end in my recordings, but I think the lack of bass is from the microphones frequency responce(roll-off at 100hz ) and not a 2 wire problem.

I will sign up for the loaner program and do a head to head compairison with the mke40's and the Church Audio mics.  Thanks for all of your help Chris, you are the man!!!  T+

[udovdh]

Distorted bass at 4 feet of the stacks?

Who/What are you talking about?

Recording loud volumes at close distance of the speakers?

[Javier Cinakowski]

Chris, who did you piss off?  You are getting T-'s like crazy.