[Liutmod]

Hello to all. I am searching for a battery preamplifier schematic optimized for Shure SM57 (or other dynamic microphones)
I need this preamp for "on the fly" recording
Many thanks in advance

[Khron]

Well that's a pretty vague project outline.

What kind of batteries are you planning to use (18650's, LiPo cells, NiMH, AA's, C/D cells)? How many of them, or how large are you thinking the whole thing should be?

[Liutmod]

I'm planning to use a 9 Volt battery or eventually two

[Khron]

Any budget limitations?

Just thinking that, if it's a single mic that you need, Tascam have this tiny SD-card recorder thingie that you just plug into the mic's XLR and you're done.

https://www.tascam.eu/en/dr-10x.html

[Khron]

http://sound.whsites.net/project66.htm

[Liutmod]

Do you know how it sounds this preamplifier?
I have found many other project on the net, but I'd like to realize something ...  tested 

[Khron]

It's the same basic design as you'll find in loads of mixers, anywhere from Behringer to Yamaha to Mackie to Soundcraft to Allen & Heath.

I doubt it has much of a "sound" - not more than an SM57 itself, anyway

[Strawtles]

I think the sm57 is a great microphone, but it is only my opinion

[squarewave]

For a simple battery powered mic pre there are quite a few options.

The simplest would probably be to just use an op amp. Or maybe two - one for gain and one for the line driver and another 20dB of gain. Like an API pre but run on +-9V.

Another option would be to use an older discrete single supply circuit. There is a fairly standard circuit for that found in a lot of older gear like Neve consoles and Studer tape machines. It uses 2-3 transistors. Here's a stripped down version of one from a ReVox reel-to-reel recovery amplifier that only uses 2 transistors:



But this is designed for 24V so things would have to be adjusted a little to get it to run on one 9V battery. And you still need a line driver circuit which is at least another transistor. This circuit has the potential to use very low power (last for days on one 9V battery) and to be very quiet because the circuit can be matched to the mic.

[Liutmod]

don't you have a final circuit ?

[Khron]

No offense, but this forum is called "GroupDIY", not "Group-have-someone-else-do-it-for-you"...

don't you have a final circuit ?

[squarewave]

don't you have a final circuit ?

Not really. Most mic pres run on +-15V or +24V and have phantom. So your requirements are a little unusual. It's very possible to make a perfectly functional mic pre with no phantom power that runs on 9V. It's just not something I've seen before. If you use two 9V batteries to make +-9V, there probably are lots of options but I still don't have a final circuit in mind. It sounds like what you really want is a PCB ready to go. So just google "mic preamp PCB". Of course there's a lot of nonsense on the web so you might try also narrowing the search down to an IC that is specifically for a mic pre. For example, google "ina217 pcb" or "that 1510 pcb" ("that" is actually the name of a company that makes audio related ICs).

[Pip]

Think 5532 chip. Do a search for schematics. See below.



https://www.banggood.com/DC-9-24V-AC-8-16V-NE5532-Audio-OP-AMP-Microphone-Preamps-Pre-Amplifier-Board-p-1119466.html?akmClientCountry=America&cur_warehouse=CN

[PRR]

> I am searching for a battery preamplifier schematic optimized for Shure SM57 (or other dynamic microphones) I need this preamp for "on the fly" recording

There is SO much you are not telling us. You will continue to get random suggestions until you tell better.

What are you going into? A radio network? Presto disk-lathe or a mike input on a pocket recorder, or a line input, or? ? ?

How much gain do you really need? If you are going to a mike input, you don't need much gain at all.

How close is the SM57 to this preamp, and how adverse is the environment? If the SM57 is within a few feet of the preamp you do not need balance input; if hundreds of feet of cable anywhere around utility power, you need careful balancing.

This has been built several times, it works, is clean up to reasonable limits. It was "noise free" in a large practice room with lots of fluorescent lights, usually some blower rumble, and 50 foot unbalanced medium-Z mike lines.

[Liutmod]

I want to connect it to a line input of a small recorder for bypassing his mic preamp
Do you think this single transistor can give me enough gain?

[radardoug]

Why dont you use the mike preamp in the recorder? What kind of recorder?

[RuudNL]

Do you think this single transistor can give me enough gain?

It depends on the input sensitivity of the line input.
(That can be anything between 40 mV and 1 V.)

[Strawtles]

Is it possible this can help you?

[okgb]

This almost seems like a troll, Do  allot , of research and see if there is something common to what people are saying and you'll probably learn something in the process.  If you're willing to accept simple circuits, then try a few and find out what works for you.
If you're trying to be cheap it maybe frustrating if you're in a hurry. No free lunches but you can always find a deal [ if you look long enough ] then come back and share your findings!

[Liutmod]

I have found this schematic with a single germanium transistor (I own).  Do you think that removing the 100k Ohm resistor it works with a 9 Volt battery?

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