Microphone pre-amp phantom supply - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th June 2015, 09:11 AM   #1
akis is offline akis  United Kingdom
diyAudio Member
 
Join Date: Jul 2008
Default Microphone pre-amp phantom supply

My son has asked me to build for him a mic pre-amp.

I have read this on the subject.
http://www.thatcorp.com/datashts/AES...ic_Preamps.pdf

I have been simulating a circuit that I believe produces the right audio levels and has enough headroom to classify as "professional audio". I attach it here.

What I am now after is the phantom power generation and any issues that might be lurking. Has anyone got any suggestions?
Attached Images
File Type: jpg mic-preamp.jpg (100.6 KB, 109 views)
  Reply With Quote
Old 6th June 2015, 11:20 AM   #2
DUG is offline DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
You could try a couple of these:

NMA2412SC Murata Power Solutions Inc | 811-1468-5-ND | DigiKey

Followed by one of these low drop out regulators:

PMIC - Voltage Regulators - Linear (LDO) | Integrated Circuits (ICs) | DigiKey
__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 6th June 2015, 12:48 PM   #3
diyAudio Member
 
JonSnell Electronic's Avatar
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
Send a message via Skype™ to JonSnell Electronic
A 48V supply is not essential, 12V will power a microphone quite happily.
__________________
Support for Flying Mole, Allen & Heath, Valve amps, older designs & 2CVs. www.jonsnell.co.uk
  Reply With Quote
Old 6th June 2015, 01:23 PM   #4
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
Quote:
Originally Posted by JonSnell Electronic View Post
A 48V supply is not essential, 12V will power a microphone quite happily.
That depends on the microphone, but many indeed work fine with 12 V and reduced resistors.

Attached is the schematic of the 48 V phantom supply that I use for my homemade battery powered stereo microphone preamplifier. The upper RCRCRC filter supplies the left channel and the lower the right channel. To compensate for the resistance in the RCRCRC filter, I reduced the resistors between supply and pin 2 of the input/supply and pin 3 of the input to 5.49 kohm each.

The inductor I used is an inductor with ferrite all around it (closed magnetic circuit) that is actually intended for loudspeaker crossover filters. It is from the brand Intertechnik and is marked "5014 Körper 0134 L=1,5 mH R=0,250 ohm diameter=0,85". The resistor and electrolytic capacitor at the bottom left are 330 ohm and 47 uF, with the original values the current peak at start-up got too large.

One thing you may have to protect your circuit against, is latch-up of the input op-amps. If for whatever reason the phantom supply comes up or goes down very quickly, the op-amp inputs may temporarily be driven beyond their supplies. That might induce destructive latch-up. Although most ICs are designed not to go into latch-up easily, I would add some small Schottky clamping diodes (BAT85 or similar) just to be sure.
Attached Images
File Type: jpg fantoom.jpg (183.3 KB, 102 views)

Last edited by MarcelvdG; 6th June 2015 at 01:33 PM.
  Reply With Quote
Old 6th June 2015, 09:06 PM   #5
akis is offline akis  United Kingdom
diyAudio Member
 
Join Date: Jul 2008
Many thanks.

I have looked into it a bit more and the design depends on what you have available. For example if you have a transformer you may try a voltage doubler. In my case I have +/-12V DC supplies and the only reasonable ways to get 48V DC are (a) a charge pump/voltage quadrupler or (b) a DC DC flyback like the LM2577/LM2588 (the latter being expensive).

Looking on ebay there are some such DC-DC modules quite cheap so I have got 2 of them to try out.
  Reply With Quote
Old 6th June 2015, 09:16 PM   #6
diyAudio Member
 
grhughes's Avatar
 
Join Date: Mar 2005
Location: Cubicle Sweet Cubicle, Springfield, Missouri, USA
Here is a Power One linear supply on ebay that is already built. This is what I use in my mixer. Power One HB 48 0 5 A Open Frame Linear DC Power Supply 48V 0 5A | eBay
Ray
__________________
" "The fool doth think he is wise, but the wise man knows himself to be nothing but a fool." Will Shakespeare
  Reply With Quote
Old 6th June 2015, 09:23 PM   #7
diyAudio Member
 
grhughes's Avatar
 
Join Date: Mar 2005
Location: Cubicle Sweet Cubicle, Springfield, Missouri, USA
Here;s the same model even cheaper. http://www.ebay.com/itm/POWER-ONE-HB...item259cb066fb
__________________
" "The fool doth think he is wise, but the wise man knows himself to be nothing but a fool." Will Shakespeare
  Reply With Quote
Old 29th July 2015, 09:51 PM   #8
Jsixis is offline Jsixis  United States
diyAudio Member
 
Join Date: Feb 2011
Location: Columbus Ohio
Universal Preamp/ Mixer
48V Phantom Feed Supply for Microphones

perfect projects lots of more on that website
__________________
I know nothing, so learning is really awesome.
  Reply With Quote
Old 30th July 2015, 05:03 PM   #9
Ketje is offline Ketje  Belgium
diyAudio Member
 
Ketje's Avatar
 
Join Date: Dec 2012
Location: Flanders
The first problem is, where do I get a high voltage for the phantom.
Separate transfo or SMPS or ...
Normaly there is a power source for the +-12V (transfo+rectifier).
From the same transfo it is easy to also get the voltage for the phantom circuit.
Mona
Attached Images
File Type: jpg NP&3x.jpg (29.2 KB, 30 views)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Phantom power preamp for microphone liquidfuzz Instruments and Amps 3 14th January 2015 01:25 PM
DIY Microphone circuit w/phantom power?? krienert PA Systems 16 19th January 2012 08:46 PM
Using INA217 for Microphone Pre-amp nyk Analog Line Level 1 8th December 2011 12:50 PM
Balanced+Phantom powered Guitar Pre-amp RonNovy Instruments and Amps 2 22nd May 2008 08:32 PM
Power Supply For Pre/ Head Phone & Phantom... (PCB) Ayne Power Supplies 0 28th April 2007 04:10 PM


New To Site? Need Help?

All times are GMT. The time now is 10:52 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright ©1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2