I think I already have a rail splitter built up from another project, its got 2 biggish caps on it but I can make it fit. What I have right now is opa134, I do have 2 x 2.2 uF electrolytic caps. uhh.. toggle I just have standard on and off?
I just measured the voltage from my soundcard.. its only at 2.3V.. why is it so low? I thought it was supposed to be at 5?
This is my "powersupply" http://headwize.com/images2/cmoy2_5.gif
I just measured the voltage from my soundcard.. its only at 2.3V.. why is it so low? I thought it was supposed to be at 5?
This is my "powersupply" http://headwize.com/images2/cmoy2_5.gif
alright, I dont think there is any cheap way to do audio =P . I will have to go buy more components. Can someone just confirm that I can use linkwitz preamp schematic, and double it up for a stereo? also can I just use my opa134 instead of the opamp he uses?
thanks
so basically this sketch x 2? wired to 1 stereo ouput.
thanks
so basically this sketch x 2? wired to 1 stereo ouput.
I already mentioned that you can order a sample from TI.
When I first learned how to make this, I was looking at three things: the first was SL's schematic, the second was the opamp datasheet (for pinouts), and the third was the TLE diagram here (noise-reduction version).
There are pictures in both the AnandTech and diyAudio threads. None of the builds are truly optimized as of yet so I would not recommend duplicating them, but you can certainly get an idea of how to do it on your own.
The last pic in the diyA thread is for a two-9V battery single channel build in an Altoids tin. You'll note that the decoupling caps were added to the top side of the board. The wire length between supply pin and cap lead is minimized this way, and removal is very easy. Installation is moderately difficult. Putting the supply cap underneath the board with one lead each in the same holes as the supply pins is very easy, but removal can be annoying. Wire length is higher compared to top-side installation, but you reduce hole usage which can become an issue.
The last pics in the AnandTech thread are for a wall-supplied dual channel capable build, also in tin size. Note that neither build uses the exact same parts as described in the parts list. The only major difference that you should not emulate is the use of a 22uF input cap on the latter build; roll-off is dangerously low.
As for the 3.5mm line-in, you can use a stereo 3.5mm male to dual RCA male cable. Most of these are pretty cheap, though, so be careful if your environment is very noisy.
When I first learned how to make this, I was looking at three things: the first was SL's schematic, the second was the opamp datasheet (for pinouts), and the third was the TLE diagram here (noise-reduction version).
There are pictures in both the AnandTech and diyAudio threads. None of the builds are truly optimized as of yet so I would not recommend duplicating them, but you can certainly get an idea of how to do it on your own.
The last pic in the diyA thread is for a two-9V battery single channel build in an Altoids tin. You'll note that the decoupling caps were added to the top side of the board. The wire length between supply pin and cap lead is minimized this way, and removal is very easy. Installation is moderately difficult. Putting the supply cap underneath the board with one lead each in the same holes as the supply pins is very easy, but removal can be annoying. Wire length is higher compared to top-side installation, but you reduce hole usage which can become an issue.
The last pics in the AnandTech thread are for a wall-supplied dual channel capable build, also in tin size. Note that neither build uses the exact same parts as described in the parts list. The only major difference that you should not emulate is the use of a 22uF input cap on the latter build; roll-off is dangerously low.
As for the 3.5mm line-in, you can use a stereo 3.5mm male to dual RCA male cable. Most of these are pretty cheap, though, so be careful if your environment is very noisy.
i'll need the 2 channels, im planning binaural recordings later. my rush is because I have a concert I want to test this out on... friday!
oh.. the opa2134 aren't for sample.. and they dont have them in stock. will the TLC2202CP work? http://www.ti.com/lit/gpn/tlc2202
oh.. the opa2134 aren't for sample.. and they dont have them in stock. will the TLC2202CP work? http://www.ti.com/lit/gpn/tlc2202
I just looked at linkwitz http://www.linkwitzlab.com/images/photos/mic-amp.jpg .. and he has no rail splitter.. virtual ground and everything you were mentioning. lol. now im really lost to where that would go.
ugh. seems like i lost the edit button.. wierd. anyways. I was looking at this. http://www.swarthmore.edu/NatSci/echeeve1/Ref/SingleSupply/SingleSupply.html and I think I get how to use the virtual ground.. So I run 18V through the chip, take 18 as a positive and 9 as the virtual ground and connect the rest like the linkswtiz diagram!
nukaidee said:
Hi
Just use the linkwitz design and replicate the other channel for stereo by using the unused opamp. You will most likely change 1 resistor to set the gain higher because 100dB SPL = 40 mV is too low for recording live stuff... unless it's hiphop house techno jungle bass at a DJ GIG.
Forget the rail splitter doesn't get anything just complexity/confusion for u. Sorry but 454 seems to have OCD on them for his stuff.
Why can't one use a NE5534 or 5532 ? It has slightly lower noise than OPA2134 etc. Additionally it's cheaper and easier to find as DIP or SMD version. We are also using low value resistors and so it's higher input current shouldn't matter. DC current consumption is about the same for both chips.
Any simple single chip smps implementation to generate -9V from the battery ? That will take care of the ground issue and need only one battery . Or how about a small smps for +/- 9 V from D sized cells ? Should last a long time.
Edit: Negative rail using a NE555 at
http://freecircuitdiagram.com/2008/...rovides-negative-supply-from-single-positive-
supply/
Any simple single chip smps implementation to generate -9V from the battery ? That will take care of the ground issue and need only one battery . Or how about a small smps for +/- 9 V from D sized cells ? Should last a long time.
Edit: Negative rail using a NE555 at
http://freecircuitdiagram.com/2008/...rovides-negative-supply-from-single-positive-
supply/
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ashok said:
Hi
Good thoughts
I'm sure Linkwitz considered the NE parts, as they were the workhorses for many years.
SMPS and LN lowlevel preamps used in tandem is a EMI/conducted noise nightmare waiting to happen. Don't do it unless as a last resort and then you have to do a lot work to get it right. Besides there are much better choices than a 555 for that.
The best choice if you really need to save 1 battery is biasing the opamp at 1/2 Vcc and using a few more big caps for DC block and bypassing.
keep it simple just add another 9V battery.
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