Rookie with a few concerns

Hello!
I am a complete noob when it comes to diy gear, and pretty much to electronics in general. But it has got me very interested and curious.

I thought I'd start with a mic preamp, specifically a neve clone from audiomaintenance or sound skulptur, haven't really decided yet so if you have any input regarding that it's also much appreciated!

Anyway, to my question: I have just bought a  fairly expensive audio interface, and I'm a little worried that something in the build process could go wrong and the preamp ultimately would damage my interface, or microphone for that matter.

Is this a concern I should have, or is it pretty straight forward and safe?  I guess the phantom power is my biggest concern, and that it would somehow go through to my interface.

Thanks in advance!

paint by numbers kits,  pretty straight forward, nothing to hard.  Shouldn't be any real issue.

As always I recommend starting with cables to get your soldering feet went.
Next move into building passive circuits like a passive DI.  this will help in trouble shooting and more soldering skills.
Then move into doing basic repairs.
last move into building gear.

Probably the safest option is to build a mic pre with input and output transformers. That way there is little or no chance of unexpected dc voltages exiting the output or input and damaging other gear.

Cheers

Ian

I say get stuck in ,whats the worst your gonna do ? you can use a cheap dynamic to test things out in any case .
Practise soldering first on scrap boards ,desolder ,resolder ,do get high quality solder ,the proper leaded stuff don't mind the RoHs bulls**t . Solder sucker,wick and flux paste are also handy to have , temp controlled iron of the correct wattage as well.

Not really. If the audio interface is vaguely new it should have proper input protection to handle spikes and probably 48V indefinitely but generally, it is considered a bad move to apply 48V to one of the audio interface ins/outs. But if you already knew that, then I think you'll be ok.

However, generally speaking, it is somewhat important to have an understanding of the relationship between voltage, current and power. For example, if you put 9V across an 8 ohm resistor, you will get 9V / 8 ohms = 1.125 amps current. Power is then 1.125 amps * 9V = 10.125 watts. One of those standard little resistors is usually rated for 0.25 watts. Power in this case is going to be dissipated entirely as heat. So that little resistor is going to get very hot. It might even smoke. Smoking electronics is bad.

But just to be sure, test everything with cheap gear.

pucho812 said:

paint by numbers kits,  pretty straight forward, nothing to hard.  Shouldn't be any real issue.

As always I recommend starting with cables to get your soldering feet went.
Next move into building passive circuits like a passive DI.  this will help in trouble shooting and more soldering skills.
Then move into doing basic repairs.
last move into building gear.

Click to expand...

Thanks for the tips! Yeah I should probably improve my soldering a bit before doing something "for real". I've wired a guitar from the ground up which turned out ok, but that's about all I've done solder-wise. I was thinking of doing the DIYRE SB2 passive summing mixer, so maybe I'll start with that!

ruffrecords said:

Probably the safest option is to build a mic pre with input and output transformers. That way there is little or no chance of unexpected dc voltages exiting the output or input and damaging other gear.

Cheers

Ian

Click to expand...

Ah thank you, that's good to know! The kits I've been looking at include transformers on both input and output, so maybe I can feel a bit more calm. I should probably read up on how transformers work cause I really have no idea, except that they can sound great 

Tubetec said:

I say get stuck in ,whats the worst your gonna do ? you can use a cheap dynamic to test things out in any case .
Practise soldering first on scrap boards ,desolder ,resolder ,do get high quality solder ,the proper leaded stuff don't mind the RoHs bulls**t . Solder sucker,wick and flux paste are also handy to have , temp controlled iron of the correct wattage as well.

Click to expand...

Yeah I think I'll just do that and see how it goes! Luckily the kits aren't that expensive, so if I try it out with a cheap mic and an old interface, maybe worst case scenario is that I have a non-working preamp.

I'm gonna follow your advice and get some lead solder and a controlled iron. The iron I have now is fixed temp, really clunky and hard to use.  I'm a little confused about what is regarded high quality solder though. There are so many choises... I found some on Amazon consisting of 2% copper, 60% tin, 38% lead and 2% flux. Does that sound okay?

squarewave said:

Not really. If the audio interface is vaguely new it should have proper input protection to handle spikes and probably 48V indefinitely but generally, it is considered a bad move to apply 48V to one of the audio interface ins/outs. But if you already knew that, then I think you'll be ok.

However, generally speaking, it is somewhat important to have an understanding of the relationship between voltage, current and power. For example, if you put 9V across an 8 ohm resistor, you will get 9V / 8 ohms = 1.125 amps current. Power is then 1.125 amps * 9V = 10.125 watts. One of those standard little resistors is usually rated for 0.25 watts. Power in this case is going to be dissipated entirely as heat. So that little resistor is going to get very hot. It might even smoke. Smoking electronics is bad.

But just to be sure, test everything with cheap gear.

Click to expand...

It's a UAD Apollo 16 mk2 so it's pretty new. I guess it should have some kind of procetion then, which is reassuring. I'm aware it's a bad move to apply phantom power to the interface ins/outs, I was just worried that I would wire something wrong leading to phantom power there instead of to the mic and damage the interface. Maybe I'm over thinking the whole thing

I know rather little about voltage/current/power/impedance so I really appreciate that little lesson! I'll read up some more on the subject before getting my hands dirty for sure!


Again, thank you all so much for the great answers! Good to know there's a community with so many helpful people here. I have a feeling electronics and the DIY thing is gong to become a new addiction of mine.. Unless I screw up royally somewhere along the way  :

Try and find a reputable brand of solder ,Ersin multicore is great ,Kester comes highly recomended also ,but there are many others too.  60/40 tin lead is the usual ,sometimes small amounts of copper are added to prolong the tip of the iron ,sometimes a small proportion of silver is added too ,your flux runs down the middle of the solder wire ,this helps the solder  to flow and keeps it from turning to crud .               

The passive mixer sounds like a good plan ,I think you can't really do any damage with that even if its wired wrong . Big clunky iron isnt going to be much good for smaller stuff    ,and theres a good chance you could damage a smaller board with this.  Dwell time on the work piece  is hard to get down  when your starting out  ,having the right stuff will make life much easier . Do also ventilate or filter the smoke from the solder as you work ,it contains lead vapour after all  .

I've used 63/37 Kester for many many years and no complaints.  I can't recall which variation I use re. the rosin core...need to look at the roll next time at the workshop.

Eutectic solder is a "magic answer" for both newbies and Old Pharts as well.

Bri

Kester Solder 63/37 Rosin Core44  is what I use....

Seems nice....

Easy to work with///

Another vote for Kester 63 / 37

For some reason I started out with Alpha Metals brand solder and have just stuck with it.  Currently have 63/37 .032" and 63/37 .015" on my bench

Joel K said:

Is this a concern I should have, or is it pretty straight forward and safe?  I guess the phantom power is my biggest concern, and that it would somehow go through to my interface.

Click to expand...

Well Being totally honest if you have that concern it's because you still don't have the knowledge to understand how phantom power works and how to measure it and you also still don't understand signal flow, so you are far from ready for this build.

Like Pucho sugested you should start with some cables.
Then try some guitar fx pedals or DI boxes, those are simple circuits and great to learn.