Disease8

First of all HI! And thanks for the great posts and info on this forum its already helped me so much in giving me inspiration to learn about electronics, been a sound engineer for a while and this side of things needs more attention...

I just build my first mic (yay) its just a small tweeter from a hi fi speaker I cannibalized with the + and - attached to the - and + of an xlr lol.. Pretty easy first project and sounds bad but was good to do. At first I had problem with buzzing but just tied the shield wire surrounding the two in the XLR (Ground or earth right?) to the metal body of the speaker stopping the buzzing...

Next thing I want to do is make my own horrible sounding preamp from the bits and pieces I have lying around.. I say horrid because I only have the low quality components taken out of normal consumer stuff that was getting chucked out, and this is all leading to me hopefully doing the Royer mod on my AKD A51 so want to start really simple before I invest in hi quality caps.

Please could anyone show me a schematic or tell me roughly how to make a very simple pre amp for dynamics (no phantom power this time maybe soon). I have resistors and mainly electrolytic caps but I think there are some different types of caps in the hi fi circuit I ripped out. There are some ceramic ones and some that look like bits of wax. Are these smooth "blob" ones that are mainly dark brown and dark green better than electrolytic ones?

Any help, guidance and support would be much appreciated in my early days of electronics!
Thanks Dom...


jdbakker

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #1 on: February 14, 2010, 08:30:44 AM »
You could do worse than hooking the mike up unbalanced and using Rod Elliott's Project #13:



JDB.

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #2 on: February 14, 2010, 08:42:31 AM »
Hi there thanks for the reply but I think this is even too complex for me.. Is there something much more simple? Like just a transistor, few caps and resistors and maybe a mains power supply? I have a couple of transformers ripped out of consumer tape deck and hi fi system.. I was looking at this simple preamp http://www.reconnsworld.com/audio_simplepreamp.html..

This looks easy, but could I simplify it for dynamic mics only? Maybe ad mains power?
Look forward to your responses (literally trying to make it now)...

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #3 on: February 14, 2010, 08:46:29 AM »
Could I somehow reverse this circuit: http://sci-toys.com/scitoys/scitoys/computers/solderless/amplifier.html
So its a preamp? This looks like a much easier beginner circuit maybe if you have an idea to adapt this?....

jdbakker

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #4 on: February 14, 2010, 08:46:45 AM »
http://www.reconnsworld.com/audio_simplepreamp.html..

This looks easy, but could I simplify it for dynamic mics only?

Leave out R1.

JDB.

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #5 on: February 14, 2010, 08:53:37 AM »
http://www.reconnsworld.com/audio_simplepreamp.html..

This looks easy, but could I simplify it for dynamic mics only?

Leave out R1.

JDB.

Wicked thanks man... Wow just leaving one resistor really makes a difference! Shall I use a 9 volt power supply, or is there a very simple way for me to use AC mains power? I'm in UK so 240v...


[silent:arts]

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #6 on: February 14, 2010, 09:05:13 AM »
you can use a wall-wart, or any another external PSU.

with this:
Hi there thanks for the reply but I think this is even too complex for me.. Is there something much more simple? Like just a transistor, few caps and resistors and maybe a mains power supply?...
I would leave my hands off the mains for now ...

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #7 on: February 14, 2010, 09:29:23 AM »
you can use a wall-wart, or any another external PSU.

with this:
Hi there thanks for the reply but I think this is even too complex for me.. Is there something much more simple? Like just a transistor, few caps and resistors and maybe a mains power supply?...
I would leave my hands off the mains for now ...

ok cool I think that is good advice... so how would I hook up a normal 9v power supply to this circuit? I don't think I have a male power plug to wire onto circuit... Just wrap the wire around it?


12volts

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #8 on: February 14, 2010, 09:39:47 AM »
I might alienate myself forever on this forum .... but I think the original post is a wind up.
Sorry folks if I am wrong.

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #9 on: February 14, 2010, 10:05:40 AM »
I might alienate myself forever on this forum .... but I think the original post is a wind up.
Sorry folks if I am wrong.
Why would you say that? people won't want to help me if you say that? Had enough trouble trying to get help on homerecording.com...


Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #10 on: February 14, 2010, 10:13:44 AM »
how do I tell what uf polyester caps are? The electrolytic ones say on the side but poly's don't. Maybe just stick to Electrolytic or will there be a massive difference in sound quality if I use poly's? I know I said I don't mind about sound quality but if its easy then why not, I got lots of poly's and electro's, having trouble finding right uf though 0.1 uf.... Does it matter what voltage they are?
Sorry for so many questions.

Mark Burnley

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #11 on: February 14, 2010, 10:16:50 AM »
0.1uF can be written 100nF or just "100n"

...or 0u1

Or even "104" meaning 10 with 4 "0's" or 100000 pF

what make polys??

Mark
O_O tape is life O_O

Mark Burnley

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #12 on: February 14, 2010, 10:19:53 AM »
...I think Zebra50 had a schem from a well known british component seller/holiday camp that used a single op-amp and input transformer. I built a few channels for a miniature front end for a portable MD recorder years ago.

Didn't sound too bad IIRC?

Mark

EDIT>

Original Post

schem from xaudia
« Last Edit: February 14, 2010, 10:25:05 AM by Mark Burnley »
O_O tape is life O_O

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #13 on: February 14, 2010, 10:26:00 AM »
No brand just green or orange blobs.. They say things like: 2A104J

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #14 on: February 14, 2010, 10:29:45 AM »
The electrolytic caps are Acom, yec, capxom...etc
Only a couple that are 0.1uf maybe I could use slightly higher value like 3.3uf?

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #15 on: February 14, 2010, 10:33:38 AM »
...I think Zebra50 had a schem from a well known british component seller/holiday camp that used a single op-amp and input transformer. I built a few channels for a miniature front end for a portable MD recorder years ago.

Didn't sound too bad IIRC?

Mark

EDIT>

Original Post

schem from xaudia

wow ok so if I look out for some opamps on the circuit boards I'm dissecting it could make it very easy

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #16 on: February 14, 2010, 10:51:34 AM »
ok one more question about the transistor...

is the only type of transistor that will work? 2N3904?
Most of the transistors I have seem to say C945 P 21E, a big one that says A928A Y-151, R1003 C201...etc

sorry again for so many questions and thanks again for the help so far... Got the resistors and caps (I think) just trying to find a transistor.. Also would like to use a pot I have to control gain and maybe add an LED but not important...
« Last Edit: February 14, 2010, 10:53:31 AM by Disease8 »

Sleeper

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #17 on: February 14, 2010, 11:20:42 AM »
you can use alternate transistors.
what you need to do is look up the following things.
1: NPN  and PNP transistors.   this will give you the information you need to read the schematic.
2: look up 2n3904 transistor datasheet.  is the transistor an NPN or a PNP - I know but I'm not going to tell you.
3: look up the datasheet for the transistor you want to substitute. make sure it is the same type.
4: as you read the datasheets a bit more carefully you will see similarities and differences in specifications.
once you have that information, come back and ask an informed question at the forum and you'll get an informed answer because the people here can bring that.

Disease8

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #18 on: February 14, 2010, 12:06:28 PM »
you can use alternate transistors.
what you need to do is look up the following things.
1: NPN  and PNP transistors.   this will give you the information you need to read the schematic.
2: look up 2n3904 transistor datasheet.  is the transistor an NPN or a PNP - I know but I'm not going to tell you.
3: look up the datasheet for the transistor you want to substitute. make sure it is the same type.
4: as you read the datasheets a bit more carefully you will see similarities and differences in specifications.
once you have that information, come back and ask an informed question at the forum and you'll get an informed answer because the people here can bring that.


Cooool man.. Learning about this is amazing! Ok so the 2N3904 is NPN... I have a transistor that I carved out of a tape deck C1815 which I found out is also NPN and is made by Unisonic Technologies...

This link is the 2N3904:

http://docs.google.com/viewer?a=v&q=cache:PYrwWGT6hh4J:www.datasheetcatalog.org/datasheet/stmicroelectronics/8850.pdf+2n3904+transistor+datasheet&hl=en&gl=uk&pid=bl&srcid=ADGEESgvF2ORvzFpvIdMYrUPuArBIq9bvGYHt50SUV70za8rD3aoY7zSbJyRbFZAfetyYYZpJAs60l_p9peb6XoMnHYuMWs8VMg7uJZ-uN_tnUHv8-QF4kk1PqI9s3trgCVKFdN2xtoR&sig=AHIEtbSGZNz7mM2MblAAke2NwG32m1YWPw

and this is the C1815:

http://doc.chipfind.ru/utc/c1815.htm

Seems it could be nice no? Its specifically for amplifying audio... do all the specs have to match?

zebra50

Re: total noob want to build SIMPLEST mic preamp sound quality not issue
« Reply #19 on: February 14, 2010, 01:09:10 PM »
...I think Zebra50 had a schem from a well known british component seller/holiday camp that used a single op-amp and input transformer. I built a few channels for a miniature front end for a portable MD recorder years ago.

Didn't sound too bad IIRC?

Mark

EDIT>

Original Post

schem from xaudia

OMG! It's Captain Kraplin! That brings back a few memories. We've all come a long way since July 2004 (although Mark and I are still here, so maybe not that far!)  :D Well done for finding both the thread and the relocated schematics (after moving server twice!)

That circuit sounds OK for what it is. I seem to recall I made a lot of changes that didn't really change it a lot. I still have one kicking round in a bok for when I need to plug a mic level thing into a random line input.
Ribbon microphone services
http://www.xaudia.com
Microphone blog


 

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