Bench Multimeter for Mic Preamp design

Ronnie4416 · 3rd November 2010, 12:21 PM

Any recommendation how many digits of resolution (4.5, 5.5, 6.5 etc.) and sensitivity (1mV, 100µV, 1µV etc.) is needed for mic preamp design?

davygrvy · 6th November 2010, 04:33 PM

Off-hand, the theoretical noise floor of a microphone is at -139dBu. But what really is it you want to measure?

http://rupertneve.com/company/notes/...nce-and-noise/

Ronnie4416 · 9th November 2010, 05:09 AM

I want to measure microphone (dynamic & condenser type) output level, audio signal and DC bias of a mic preamp.
I'm choosing between Agilent U3402A 5 1/2 digit Dual Display at $600 and Agilent 34401A 6 1/2 digit at $1,072.

Agilent Technologies Test Equipment - U3402A - Multimeters - Bench - Allied Electronics
Agilent Technologies Test Equipment - 34401A - Multimeters - Bench - Allied Electronics

slam · 11th November 2010, 08:26 AM

I heard that many of the U-series equipment are rebranded products from asia. So you may want to take that into consideration.

The HP 34401a is blue blood Agilent and has been the standard for a long time. You can't go wrong with it if you can afford it.

A used HP 3457 is far cheaper and its performance is in the same class of HP 34401a.

Ronnie4416 · 25th March 2011, 05:48 AM

A better option is 34410A since you can datalog to computer via USB interface but expensive by $200 compared to 34401A.

34401A is equipped with GPIB and RS-232 thus need to have a GPIB or RS-232 to USB adapter to interface to a PC.

Rundmaus · 25th March 2011, 06:42 AM

I think an oscilloscope will be far more useful in (pre)amp design than a multimeter...

Greetings,
Andreas

cliffforrest · 25th March 2011, 07:49 AM

Quote:

Originally Posted by Rundmaus

I think an oscilloscope will be far more useful in (pre)amp design than a multimeter...

Greetings,
Andreas

Agreed!

Get a used Tek 7000 series with a differential plug-in. you can then measure uV on top of a lot of common mode offset and noise.

DMM will read nonsence here and you'll have no choice but believe it!

Ronnie4416 · 25th March 2011, 08:28 AM

I already have a Tek TDS2012B scope. Right now I'm using a Fluke 179 (6,000 count) multimeter, will this suffice?

cliffforrest · 25th March 2011, 12:10 PM

Quote:

Originally Posted by Ronnie4416

I already have a Tek TDS2012B scope. Right now I'm using a Fluke 179 (6,000 count) multimeter, will this suffice?

That is not much use for low level measurements! 2mV/cm max sensitivity and very high bandwidth.

As previously asked - what do you want to measure?

audiomik · 11:58 AM

Re: "Right now I'm using a Fluke 179"
this is OK for AC voltages in power circuits but only has a specified AC Voltage bandwidth up to 500Hz - so not much good for Audio....
Fluke spec sheet: http://assets.fluke.com/datasheets/2155a.pdf

Let us know what you want to measure and further assistance can be given, as said before!
Mik

3rd November 2010, 12:21 PM	#1
Ronnie4416 diyAudio Member Join Date: Oct 2010 Location: Pampanga, Philippines	Bench Multimeter for Mic Preamp design Any recommendation how many digits of resolution (4.5, 5.5, 6.5 etc.) and sensitivity (1mV, 100µV, 1µV etc.) is needed for mic preamp design?

6th November 2010, 04:33 PM	#2
davygrvy diyAudio Member Join Date: Mar 2007 Location: Richmond, CA Blog Entries: 1	Off-hand, the theoretical noise floor of a microphone is at -139dBu. But what really is it you want to measure? http://rupertneve.com/company/notes/...nce-and-noise/ __________________ Think out of the box

26th March 2011, 11:54 AM	#10
audiomik diyAudio Member Join Date: Apr 2010 Location: Bath, UK	Re: "Right now I'm using a Fluke 179" this is OK for AC voltages in power circuits but only has a specified AC Voltage bandwidth up to 500Hz - so not much good for Audio.... Fluke spec sheet: http://assets.fluke.com/datasheets/2155a.pdf Let us know what you want to measure and further assistance can be given, as said before! Mik Last edited by audiomik; 26th March 2011 at 11:58 AM. Reason: add request for more information

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9th November 2010, 05:09 AM	#3
Ronnie4416 diyAudio Member Join Date: Oct 2010 Location: Pampanga, Philippines	I want to measure microphone (dynamic & condenser type) output level, audio signal and DC bias of a mic preamp. I'm choosing between Agilent U3402A 5 1/2 digit Dual Display at $600 and Agilent 34401A 6 1/2 digit at $1,072. Agilent Technologies Test Equipment - U3402A - Multimeters - Bench - Allied Electronics Agilent Technologies Test Equipment - 34401A - Multimeters - Bench - Allied Electronics

11th November 2010, 08:26 AM	#4
slam diyAudio Member Join Date: Jan 2005 Location: CA	I heard that many of the U-series equipment are rebranded products from asia. So you may want to take that into consideration. The HP 34401a is blue blood Agilent and has been the standard for a long time. You can't go wrong with it if you can afford it. A used HP 3457 is far cheaper and its performance is in the same class of HP 34401a.

25th March 2011, 05:48 AM	#5
Ronnie4416 diyAudio Member Join Date: Oct 2010 Location: Pampanga, Philippines	A better option is 34410A since you can datalog to computer via USB interface but expensive by $200 compared to 34401A. 34401A is equipped with GPIB and RS-232 thus need to have a GPIB or RS-232 to USB adapter to interface to a PC.

25th March 2011, 06:42 AM	#6
Rundmaus diyAudio Member Join Date: Aug 2005	I think an oscilloscope will be far more useful in (pre)amp design than a multimeter... Greetings, Andreas

25th March 2011, 08:28 AM	#8
Ronnie4416 diyAudio Member Join Date: Oct 2010 Location: Pampanga, Philippines	I already have a Tek TDS2012B scope. Right now I'm using a Fluke 179 (6,000 count) multimeter, will this suffice?

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