Preamp Schematics

  • Thread starter Thread starter Reggaesoldier
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OneArmedScissor said:
Very interesting...I love how virtually everthing audio and music related has a DIY alternative to buying it built for you. :)

So, exactly how difficult would this INA217 be to put together for someone who has never done anything like this before? I could use some extra pres, no matter how good, for the hell of it.

EDIT: Well, I requested the INA217AIDWT and INA217AIP. It says one of them ships October 23rd, and the other a little after. I hope I can do this, but if not, atleast it's free lol.
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It should be no problem putting together, the hardest bit is always making it look nice when it's finished :)

This is probably a good start if you're not used to this sort of thing:

http://recording.org/users/kev/kdmp.htm
 
now this seems like it could be a fun little project
 
I just use the little Rat Shak "IC experimenter" boards to assemble these. The only thing you want to watch is keeping the leads to the gain-setting pins short and don't run them close to the output lead. These boards can take two chips, but I just use one chip per board and use the other connections to keep the signal and power grounds separate. Also, I don't use the servo option, just run pin 5 (ref) to ground and put a nice cap on the output to take care of the offset voltage.
 
Out of curiousity, how many of you guys have registered at the Prodigy site and how many are staying anonymous lurkers?

:cool:
 
Sorry to resurrect an old dead thread, but I got one of those INA217 samples from Texas Instruments in. It is just one tiny little black chip thing. How big is all of it together? I was under the impression that you get both of the INA217 samples they had, and then put them together somehow, but am I right in thinking that? The other one isn't supposed to come in until November! :eek:
 
OneArmedScissor said:
Sorry to resurrect an old dead thread, but I got one of those INA217 samples from Texas Instruments in. It is just one tiny little black chip thing. How big is all of it together? I was under the impression that you get both of the INA217 samples they had, and then put them together somehow, but am I right in thinking that? The other one isn't supposed to come in until November! :eek:
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You ordered the same chip - just in 2 different packages. The one you have is the guts for a mic pre - now comes the part where you have to round up the other parts, make a printed circuit board (or direct wire it), get a box to put it in and knobs, switches, connectors etc. This is not a thing you want to do if you've never built a project from scratch.

Attached is the mic pre schematic from the 1na217 spec sheet. As you can see, you need another op amp (OPA137), various capacitors, resistors and diodes, switch, potentiometer and connectors, and+/- 15V and+48V regulated power supplies.

Unfortunately, getting the IC op amp chip was the least of your worries. You really need to buy a kit if you've never done this before.
 

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And I would add that this circuit very possibly has never been actually built, tested and used physically - only designed and tested by some EE at TI with software, and in fact may be found to have problems in actual use, so there is no guarantee it would even work correctly if you did build it.
 
I read somewhere (forgot where?) that using the servo as shown really screws up the sound. It's way better to loose the servo and just use an ele cap or some metal films in parallel.
 
Oh good grief lol. I specifically asked if this was hard to do earlier on in this thread and I was told it wasn't lmao.
 
one of the hardest things with diy mic pre's is building the bipolar power supply. which is a bit of a pain if one wants to build a few.
i'll just point you to a few that are interesting.
as well as the jensen site there are many other pre schematics. look for jlm audio who have a neve pre schematic if i remember.
also a good first pre is one at linear technologies web site.
search for the LT1115 pdf. in a few pages is a mic pre schematic. but youll need a bipolar power supply.
the reason i like this particular one is one can sub different single op amps
other than the LT1115 and do test recordings and hear how each sounds and do noise analysis useing an audio editor by recording blank tracks.
also it means one is not tied into a proprietary op amp.
there are many alternatives to the LT1115 op amp.
i tried and liked op37 style single op amps and they are one of my favorites.
make a great front end. only prob is they like juice. and consume more milliamps than some other op amps.
if you try the LT1115 schematic - just remember as always to use low noise metal film resistors. eg : dale for example. there are many others. yageo is another if i remember and low tc capacitors.
another reason i like the LT1115 approach is one can experiment with lowering the value of the feedback resistor. and take the output of this little circuit into a line mixer to feed a sound card input. and thus the line mixer with its volume control can control the level going to the sound card.
i would advise however for safety reasons if one has never done diy befor ,
to at a minimum take an electronics course to ensure (eg; adult college)
you do diy in safety. and i would stronly advise newbies to this to stay away from circuit schematics that draw lots of current or that use high voltages.
once again for safety reasons.
peace.
 
Soldering Iron Beginner

crazydoc said:
Unfortunately, getting the IC op amp chip was the least of your worries. You really need to buy a kit if you've never done this before.
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I have never done anything like this before i.e. building anything with a soldering iron but I am intrigued. Maybe a kit would be the best way to go for a beginner.

Does anyone know of any good sounding DIY preamp kits?

John
 
JohnnyMan said:
I have never done anything like this before i.e. building anything with a soldering iron but I am intrigued. Maybe a kit would be the best way to go for a beginner.

Does anyone know of any good sounding DIY preamp kits?

John
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Go here
http://paia.com/toc.htm
find something you like, and order the kit. I've never built one, but I've heard only good things about them - quality, instructions, support. They're not going to be top of the line pro equipment, but will have a use, are cheap, and will get you started in DIY with lots of support.
 
Hi Manning! :)

Funny I didn't realize you were here, but you have more post than me!
 
I would mind "getting my feet wet" with some type of DIY project involving a soldering iron but I don’t want something that I’ll regret having later (as DJL pointed out). I am definitely in the mood for upgrading my current equipment. I already have a thread started about replacing tubes in preamps http://www.homerecording.com/bbs/showthread.php?t=134059.
I have also read many posts about how great the DMP-3 is so I am currently leaning towards purchasing one of those.

I read an article in the September 2003 issue of Recording magazine by Paul Dorsey (page 50) on upgrading the components of an Octava 012 mic. I have two and thought it would be nice to improve them but the author warns you that it’s not for the beginner and I don’t to screw up those mics.

I rather fancy the idea of taking a factory built device and improving it components to dramatically improve the sound of the device.

Building a device from a kit that walks you through everything is also appealing. Especially if it’s written for a beginner and that I have a very small chance to screwing it up.
 
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