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-   -   Power supply for my "DIY" RIAA (http://www.diyaudio.com/forums/analogue-source/158586-power-supply-my-diy-riaa.html)

runethechamp 13th January 2010 11:54 PM

Power supply for my "DIY" RIAA
 
So in anticipation of a record player arriving at my door, I have decided to kind of make my own RIAA step. I picked up the phono board from an older Yamaha CX-830 preamp, and I figured I could try to make a power supply for it and see if I could at least make it work, or maybe I could even make it sound good.

What I need is a +18 0 -18 supply and I'm guessing it doesn't need to be very powerful, but from what I've read it needs to be quiet. Are there any good DIY designs out there, either here or other places. I'm considering one of Rod Elliott's designs. Does anyone here have experiences with those?

Thanks

andyr 14th January 2010 10:23 AM

Quote:

Originally Posted by runethechamp (Post 2046759)

What I need is a +18 0 -18 supply and I'm guessing it doesn't need to be very powerful, but from what I've read it needs to be quiet. Are there any good DIY designs out there, either here or other places. I'm considering one of Rod Elliott's designs. Does anyone here have experiences with those?

Thanks

If you want +/- 18v, why not use 2x9v transistor batteries for '+' and 2 for '-'? If this works, you can then make a better-sounding battery power supply by using 3x6v SLAs for '+' and 3 for '-'. That'll be "beefy" enough to last quite a long time, I would think.

Regards,

Andy

runethechamp 14th January 2010 04:19 PM

Thanks for the tip, but I'm not going the battery route, not yet at least. Any other suggestions?

leadbelly 14th January 2010 04:24 PM

IMHO you should just make yourself a +/- 18VDC power supply using LM7818 and LM7918 fixed regulators. You will find many threads here knocking fixed regulators like those as inferior to discrete or adjustable versions, but since you are implementing a consumer grade preamp board, you are unlikely to hear a difference.

runethechamp 14th January 2010 04:28 PM

Quote:

Originally Posted by leadbelly (Post 2047592)
IMHO you should just make yourself a +/- 18VDC power supply using LM7818 and LM7918 fixed regulators. You will find many threads here knocking fixed regulators like those as inferior to discrete or adjustable versions, but since you are implementing a consumer grade preamp board, you are unlikely to hear a difference.

Yeah, my first option was to do that using Rod Elliott's design. Just wanted to see if there were any other designs out there that would be easier and/or better. Not that his design is very complicated at all, but it's always good with a second opinion.

runethechamp 15th January 2010 07:31 PM

So what kind of board should I use to assemble all my parts on? I've never done anything like this before so I figured I should ask. I won't be etching my own, so what other solutions are out there?

ra7 15th January 2010 08:03 PM

I would advise against going the 7xxx regulator route (or the lm317). In my brief experience, these regulators completely wreck the sound. Simply awful sound.

I built the Le Pacific RIAA which has a very low parts count and is more sensitive to the PS than perhaps other designs.

Get a simple CRC supply, or one of the cap multipliers on Rod Elliot's pages. If you want to go one better, build a shunt reg.

There is a group buy for DCB1 boards (check in the group buy section), many people are using those as a shunt reg. It is ideal for your application and will be very hard to beat in terms of sound.

runethechamp 15th January 2010 08:21 PM

Quote:

Originally Posted by ra7 (Post 2049134)
There is a group buy for DCB1 boards (check in the group buy section), many people are using those as a shunt reg. It is ideal for your application and will be very hard to beat in terms of sound.

Thanks for the tip.

Can you give me a quick rundown of that project so I don't have to wade through 80 pages of it? I don't even know what a shunt reg is yet, but I'm not so worried about that :D

ra7 15th January 2010 08:47 PM

:)

It took me a good few months to get the hang of it.

Basically, it is a constant current source feeding a mosfet which shunts a large portion of current to ground, and the load sees only a small portion of it, thus achieving good regulation.

The group buy is for PCBs for a direct coupled B1 buffer, which is a unity gain active buffer/volume control, designed by Nelson Pass. You can find the original article on passdiy.com

Salas, another member here, added direct coupling and a shunt reg to the original B1 buffer. The shunt reg part of the PCB can be easily adopted as a PS in other designs.

If you don't want to get this deep so soon, just build a CRC supply. Again look at firstwatt amplifier power supplies, found at firstwatt.com

runethechamp 15th January 2010 09:09 PM

Hey, thanks for the info. But when you say that the shunt reg part of the PCB can be adopted to be used as a power supply, it's already too complicated for me.

Checked out the firstwatt site and couldn't immediately locate any pages just for power supplies there. I'll look around a bit more and see what I can figure out.


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