Total Newbie forum?

I know this is a bit cheeky and I only have just this week decided to start DIY'g
I can just about solder (years ago) and I eventually want to buy old mic preamps and rack them up myself
So as this is a new start - any chance of a total newbie and I mean "absolutely total" newbie forum in the future.
The main problem I have at the moment is trying to understand in total laymans terms - how to get from a UK 240v mains plug into a device (obviously a PSU) that can deliver power to two or more modules...
I have looked at Group DIY - but am still totally mystified..
I won't bother asking the questions here - any mileage in the idea of a newbie forum?

Hi UK!

PLEASE ASK THE QUESTIONS! That's how we learn and the guys are always helpful. Except for that Doc Holliday asshole :wink:

cheers,
kent

Yes, no one hear knows everything (well...). Everyone here learns from other people and everyone helps other people learn, so don't be afraind to ask.

Seth

http://doc-holiday.8m.com/

don't think its the the same "doc", but this is pretty funny

[quote author="jrmintz"]Yes, no one hear knows everything (well...).
Seth[/quote]

Well sometimes i wonder if that can really be true about PRR :wink: :shock:

To Uk just ask your questions. As this is a new start of the forum the search function won't be a good source for answers so fire away your questions. In the future when the forum here gets filled with knowledge (as the old forum was) the search function is a very important tool.

As for the psu. Normally a psu consists of two things. One is the main transformer which transforms the incoming mains voltage (in your case the 240V) to a much smaller voltage. It depends on the type of transformer how much this voltage is. Also it depends on the type of the transformer how much current it can deliver at this voltage.
The second part is mostly a small pcb containg a bridge rectifier, some voltage regulators and filter caps. The voltage regulators ensure a regulated voltage.
What psu you need for your mic preamps depends on the preamps itself. What voltage do they need ? Bipolar ? Normal choices are single ended 24V or bipolar +-15V or +-18V.
I always think that it's better to build a little overpowered psu since you have enough "headroom" and it will run cooler. And a more powerful transformer often costs only some $/pounds/euro/whatever more.

Often a pic says more then words so:

Here is a pic of a power supply together with a (torodial) transfromer. (to be exact with this pic the power supply is integrated on the main pcb)



There are also psus with onboard mounted transformers.



Flo

Thank you very much
This is starting to make sense now...
Do you mind if I take this really slowly (it may build up into one of those threads like Harvey's big mic threads)

So if I take a step backwards....
Please bear with me I would really like to know this stuff, and learning by examples is a lot easier (in your very late 30s) than studying design books.
Please feel free to comment on any item - even if it is to tell me I am out of order for being really a total newbie.

I need a mic preamp to get the level of a mic input up to the level that I can get onto tape/hard disk
To do this I feed an electrical box a mic level audio feed and some power... and out the other other end comes a line level audio feed that I can record with.
The electrical box (I assume this is the mic preamp) can not only boost my audio signal to the line level but also colour it. (make it darker/lighter/duller?sharper) (I can hear that).

I figure the best way to get into the DIY stuff I want to do is to buy a ready made electronics box (mic preamp) - feed it power and then go from there.

So I have decided I wouldn't mind buying a cheap mic preamp to start with.. and would probably decide on a Telefunken V672 (they are quite cheap) - and I would like to build a big rack of different module types.

So I will have the mic preamp - I can read a bit of German and had a look at this schematic
http://www.gyraf.dk/schematics/Neu_476.gif
(I know that the 476 is just the Neumann version of the 676 - I have done some homework!!)
By the looks of it the way of getting power and audio in and audio out of this thing is via the pins at the back of the mic preamp

So - my first question is....
Playing safe at the moment (no AC power) - how do I rig up some batteries to power the thing.. (Once I am happy on how to do this I will go onto AC power - a bit further down the line)
Over to you guys - or is this too basic? (back monday)

Yes your basic idea of a mic preamp is right. It takes a mic level input from the mic and ampflifies to line level which can go to other gear or a recorder or computer or whatever.
But a normal mic preamp also has some other features. Most if not all mic preamps have the ability to supply mics with 48V phantom power. This is needed for condenser mics as those need also power to work. And that is normally supplied through the mic preamp. Which also means that the power supply in your mic preamp needs to create the 48V in addition to the working voltage for your mic preamp.
Other features of mic preamps are phase reverse switches and pads. The G9, one of the projects here (and an incredible one !) also offers for example a high-pass filter.
Of course the sound of a mic preamp is based on it's design and the components. There are mic preamps that color the sound (like Neve) and some others are designed to be as clean and transparent as possible.

My first DIY project was to build a mic preamp. I choosed the Taos mic preamp and the green mic preamp (another popular project here). Both are very easo to make and feature cheap components (no expensive transformers and tubes). But of course you can buy a mic preamp module and rack it yourself.
Looking at the schematic of the Neumann V476 it needs a single ended 24V power supply. You can use the power supply for the neve projects as those also need 24V.
You can find it here:
http://www.vintagedesign.halmstad.net/diy/psu.pdf

As i don't have any experience with battery powering mic preamps i can't give you a solution but i guess one of the more experienced members here will step in (just a clarification i am still a beginner at this stuff and don't know nearly as much as our "gurus" here).
But i would start at using a power supply. Makes more sense i think than battery powering (that is if you don't plan on field recording).

One piece of advice (and an important one):
Whenever you work with main voltages (or ever higher voltages as found in most tube projects) be really sure to disconnect the power plug before working on the unit. I always use a portable wall socket (not sure if that's the right english word for it) and place it right in front of me besides the unit i am working. This way i can always be sure that the power really is disconnected.

Flo

Hey 03878,

One of the finest attributes of TT is that everyone is treated equal, regardless of their experience. Feel free to ask what you want, there are people here from all kinds of backgrounds.

Justin

UK, check out Eddie Ciletti's site (www.tangible-technology.com). He's got some interesting info on mic pre's and power supply.

Welcome!

Definately check out the Green Pre. It is a great simple pre that sounds good! And just jump in and start asking questions as they come up.

Joel