$5 Microphone Preamp - Sounds Better Than $1500 One?

Off-Topic
1

So, in search for an affordable but decent sounding mic pre-amp online, I stumbled across this article:
http://www.record-producer.com/learn.cfm?a=3080

Which describes a home-made pre-amp that can be built very cheaply. In their testing, it supposedly sounded better than another one that costs $1500.

I am very interested in building this myself, but I think I need a little help/clarification. I have soldered a couple of things before (mainly video game controller modifications), but I don’t have a lot of experience with reading circuit-diagrams.

I have printed out the schematic (http://www.record-producer.com/i/ina217-large.gif) , however in their description they say that you don’t even need to use all the parts there. I have crossed off the parts that it says you don’t need in my printout (the four diodes, R3, and A2). However I am not entirely sure how this will actually look when I get all the parts. Will I just need the one female XLR connector and the whole circuit will be soldered onto that? Or will I need another end for output?

Also, what is the Op-amp “INA217”? Are op-amps a generic part I can get at radio shack, or is the INA217 a specific part I need to get somewhere?
Also I see a lot of ground points, what do I connect those to? I’m assuming solder them all to a wire, and then connect that wire to the pin 1 on the XLR connector?

I just wanna make sure I’m well prepared before I do this so it goes smoothly instead of me wasting 6 hours in frustration because I did it wrong :)

I’m not sure if I’m going to make this a mess of wires, or get a little breadboard. I might just do wires & put it in a little project box. Not sure yet, although I don’t really care as long as it works. But if the 1st one goes well, I’m going to make a second, nicer one, for my girlfriend.

Any help is appreciated :)

2

So… where do you buy this INA217???

3

Save your bikkies for pro gear. You’ll never regret it. Modern tube hybrids are fantastic. If you shop around you can get a great deal, maybe even around $USD800. Excellent item worth aiming for with a long term goal - especially for vocal recording.

4

I seriously cannot spend that kind of money. I would have trouble even justifying $100 right now. Supporting a family with only my (not so great) income is not exactly conducive to getting awesome hardware. I’m amping it right now through a mixer which works reasonably well, but I’m going to build this thing if I can find the parts. :)

5

that’s why he said long term goal… ;)

6

Thanks man! Do you know what the difference between the “595-INA217AIP” and the “INA217AIPG4” is? I guess I will get two of the 595-INA217AIP :)

7

Fawk. I’ll call Radioshack first before I try to find an online retailer

8

I tried to order some “free samples” directly from TI, which failed. Anyway, I found a retailer and ordered a couple. Wish me luck! I will post pictures & story when I’m done :)

9

…is that some magic tube amp modelling processor? if so, I’m game… ozone’s tube simulation makes me all warm inside… and it’s software… so I presume it’s possible to do similar things on ICs. The only big issue I see with ICs is how much volume you can get.

10

I really don’t care about uber high quality at this point, I just want something cheap that will cleanly get my mic up to an acceptable level to plug straight into my soundcard.

If I’m able to make it though, I can build you one :)

11

I want a cheap pre-amp as is… I was going to look into using a computer speaker amplifier actually. There are some that are really high quality, and you can pick them up for like $5 at second hand stores. I figure, I might have to spend $20 to get an amp that doesn’t colour the sound too much, but I will eventually find what I’m looking for. In fact, the computer speakers sitting on my desk at work right now are a small set of KOSS speakers that would probably do just what I want. All I really need is something that will lower the noise floor on whatever it is I’m recording… my laptop has horrible line noise.

Also, just occurred to me, to get the best quality out of a cheap amp like this, try to find a regulated DC power supply… it will completely flatten the DC wave and keep it at a constant voltage, removing noise that can interfere with recording.

If I end up “making” an amp like this, and it works nice, I’ll post my results on the forum.

12

Maybe you should get a usb soundcard for your laptop?

13

Ok. I got my INA217’s in the mail today. Off to radio shack sometime this week to get the rest of my parts and I’ll start soldering this weekend :)

14

$$$$$ :P

15

Took me long enough but I finally got a chance to get down to radio shack and get the rest of my parts. It cost a little more than I expected to because I had trouble finding the exact resistors that I need.

Fortunately there was an old guy that worked there that knew how to read circuit diagrams and was able to ask some of my questions about where to solder things based on the circuit diagram. It’s all still a bit overwhelming, but I’ll try my best & get started this weekend. Will post a progress update next week

16

I bet all the parts are sitting in a desk drawer somewhere, not being used. IO, if you want, send those parts my way, and I’ll put em together for myself :P … I’ll pay you what you payed for them, plus shipping ;)

17

I have a PAiA tube preamp kit sitting in a box in my basement. I got 90% of the way through it and got confused. In 2005.