Is there aDIY mic pre equivalent of the Chip Amp?

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santiu

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Hey, so i came across this link while reading the "Pre Amps, what are they good for? Absolutely..." thread:
http://www.record-producer.com/learn.cfm?a=3062

It got me thinking. Is there a well recognized DIY chip based mic pre out there that's sort of the recording enthusiasts equivalent to the ChipAmp for audiophiles (maybe using the INA217 he used, or maybe some other IC)?
 
Check out Five Fish Studios . . .

By the way I don't see what is special about the ChipAmp. It looks extraordinary simple . . . sometimes simple can be good, but I think I could build that on perfboard, so I'm not sure why I would buy the kit.
 
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I use the INA217 for many of my DIY preamps, They are really easy to work with and Offer very good sound quality....And because of the ease of use a PCB design is usually really easy to come up with, I just designed a 4ch
INA217 preamp with an onboard Regulated PSU and Phantom power and the PCB is only about 6in x 3in , I"m still working out the bugs but so far it seems very promising.....

Cheers


PS: the Green Pre is also a Good preamp , It was my first DIY preamp but I feel I like the sound of my INA217 preamps more then the Green Preamps and the INA217"s are easier to build and have Far less components.....

:D
 
cnix said:
http://www.seventhcircleaudio.com/
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are you referring to the T15 model? That looks to be their only super simple topology circuit. Haven't been able to find many reviews on it, but the few I have come across seem favorable. At only $79, i'm might not be able to resist trying one.

The Five Fish Studios kit looks nice too. (mshilarious, i only linked to that ChipAmp kit for reference, many people build without PCBs due to their simplicity)

Minion said:
I use the INA217 for many of my DIY preamps, They are really easy to work with and Offer very good sound quality...
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Minion, Do you just follow the suggested circuit in the datasheet? Or is there a preferred circuit layout people like to use?

thanks for the suggestions guys :D
 
Seems I remember a good bit of talk about these over at GS.

Charlie
 
santiu said:
The Five Fish Studios kit looks nice too. (mshilarious, i only linked to that ChipAmp kit for reference, many people build without PCBs due to their simplicity)
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I'm just saying none of these recommended kits are the mic pre equivalent of the ChipAmp. For a decent mic pre, you need a good two-sided power supply, a phantom supply, a reasonable meter of some type, input and output protection, some of these designs use servos to avoid coupling caps, etc--and a case!

The mic pre equivalent of the ChipAmp would be something like a single OPA2134 strapped to 2 9V batteries, +18V phantom, a single clip LED, a gain pot, coupling caps, and a step-up output transformer to make up for the relative lack of headroom and gain. That's a good pre within its limitations, excellent for portable use, but for a professional studio product, that won't really cut it.

I don't think I would even consider driving my mains with ChipAmps, that's all. Given the cost of output transformers vs. the cost of a real power amp, it might even be cheaper to buy (although I didn't read enough to know if ChipAmp had to have trafos, it seems that they were using them). I have a 6 channel power amp that would completely destroy ChipAmp, and I scored it for $275 on the Bay. DIY is fun and all, but let's be serious about make vs. buy decisions.

For preamps, it is rather different. All the extra-cheap pres mostly throw in tubes for garbage, or add silly features that aren't helpful. The cheapest good rackmount IC pre I know of is the Rane.
 
mshilarious said:
For preamps, it is rather different. All the extra-cheap pres mostly throw in tubes for garbage, or add silly features that aren't helpful. The cheapest good rackmount IC pre I know of is the Rane.
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Hi mshilarious. What about the DMP3? Wouldn't this also be in the same league as the Rane MS-1b? I've been really impressed with mine so far!
 
Minion, Do you just follow the suggested circuit in the datasheet? Or is there a preferred circuit layout people like to use?
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I generally use the INA217 datasheet Mic preamp curcuit with a few changes,
Depending on the Preamp I am building I will sometimes add the Dc Servo curcuit But I have also Cap coupled the output of the INA217 without the servo and still gotten good results....I will sometimes also add a Dual Opamp configured as a Ballanced Line driver at the output of the Ina217 to create a ballanced output but with my Unballanced recording equipment I find it isn"t nescessary..I also sometimes drop the Hot plugging protection curcuit because I never Hot plug my Mics...

You can design a Basic Ina217 preamp onto a pretty small PCB ,Probably less than 2in Square per channel....

Cheers
 
LOL. I've got a kaboodle of parts including THAT pre chips from when I was gonna build something.
 
santiu said:
Hey, so i came across this link while reading the "Pre Amps, what are they good for? Absolutely..." thread:
http://www.record-producer.com/learn.cfm?a=3062

It got me thinking. Is there a well recognized DIY chip based mic pre out there that's sort of the recording enthusiasts equivalent to the ChipAmp for audiophiles (maybe using the INA217 he used, or maybe some other IC)?
Click to expand...

That $5 pre-amp is running on batteries (cleanest DC source there is). If you had to use a power supply, the cost would rise at least $50-75 more. A decent case (with labor) would add at least another $20-40.

The guts of many projects never really cost much (except transformers), but the cost to package it (like a more expensive pre-amp) adds much more to the cost (even in high volume production).

So, the article and test are pretty misleading since virtually all pre-amps from $50 - 500 use the same IC pre-amp chip.

The second part is that there is very little chance that you can tell any pre-amp judging a single track since the better pre-amps don't impart nasty stackup artifacts in multi-track recordings. You really have to hear a pre-amp with at least 8 tracks to know what it will add. I used a Behringer board once that was OK at the start of the recording. At 20 tracks it showed how crappy it really sounded. It stacked this really nasaly sound in the mix. What a nightmare.
 
You can actually build a Regulated PSU for these Mic preamp for less than probably $20 , Just a couple LM7815/7915 or LM317/337 Regulators for the IC and then another LM317 for the Phantom power, a Small Bridge rectifier , Maybe 4 1000uF caps and maybe 4 100uf caps and a couple 10uF caps and a Handfull of Resistors and a few 1N4007 diodes and of cource a small transformer and a Piece of PCB material....(all this stuff actually costs less than about $10 if you know were to get parts)

I picked up a Dozzen small Transformers (15v 0v 15v) for about $5 on e-bay and they are perfect for small Preamp PSU projects.....

My Latest 4ch INA217 project probably cost about $30 includeing the PSU ,Chassis ,XLR Jacks ,RCA Jacks , Pots and Preamp PCB and Parts....Many of the parts were slavaged and the Chassis was taken from an Old Midi controller thingy but most of the components were new......

Cheers
 
dickiefunk said:
Hi mshilarious. What about the DMP3? Wouldn't this also be in the same league as the Rane MS-1b? I've been really impressed with mine so far!
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I suppose, but I stipulated rackmount. I also prefer internal power supplies, when you have a rack full of gear wallwarts are just a hassle.
 
i was wondering about these diy preamps. do you need any expeirence in these or can you just jump in and make one of the cheaper seems to me easier ones?
 
gdavi1 said:
i was wondering about these diy preamps. do you need any expeirence in these or can you just jump in and make one of the cheaper seems to me easier ones?
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Well you could fit what I know about electronics on the back of a postage stamp but I've built some decent gear (including three different mic pres). There are some really great, well documented projects out there with PCBs and even parts kits available. The full kits from 7th circle and JLM et al are good and probably easiest of all but they are pricey.

Make a guitar pedal or two and once you're confident with your soldering I say go for it.

Group DIY is a great resource although a difficult forum to get signed up at (you can still read everything there though).

http://www.prodigy-pro.com/forum/
 
Where's the best place to get the INA217s, guys? Mouser seems to be out. :)

I'm thinking about using this chip for a senior level electronics project so I can GRADUATE! :D Probably only to go back for my Masters degree because that will hopefully mean a better home studio! lol Anyway...

Any help in sourcing a couple of INA217s would be great.

Thanks!

Brandon
 
NeveSSL said:
Where's the best place to get the INA217s, guys? Mouser seems to be out. :)

I'm thinking about using this chip for a senior level electronics project so I can GRADUATE! :D Probably only to go back for my Masters degree because that will hopefully mean a better home studio! lol Anyway...

Any help in sourcing a couple of INA217s would be great.

Thanks!

Brandon
Click to expand...

Digikey has some stock . . . maybe your senior-level project should be "how to source parts" :p
 
You can also probably get them from Texas Instruments ,They sent me 12 in free samples , If you sign up there they might send you a few as free samples and if they do they are usually delivered to your door within 2 days...

You might also look at the THAT1510 as it is a Pin for pin replacement for the INA217 but has slightly better Performance/Noise specs....

I wouldn"t consider an INA217 preamp project a senior level electronics project ,it is more of a beginner project but I guess it gets more advanced if you use the DC servo and Ballanced line driver and Hot plugging protection....


Good luck
 
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