Easy DIY RIAA-preamp wanted.

kmj · 17th March 2004, 02:11 PM

Hi, I am in need of a preamp for my old turnable.

It seems that the guys at HK neglected to put a phonoamp in my reciever......

so instead of buying one i thought that i perhaps could start up a new hobby and build one myself. But since there are so many schematics out there i thought that you guys could recommend one thats quite easy to build and with complete schematics for powersupply and amp-stage....

anyone got any suggestions?

imput sencitivity and impedance of the existing amp is 200mV and 47kOhm

Keld · 17th March 2004, 03:18 PM

Quote:

Originally posted by kmj
recommend one thats quite easy to build and with complete schematics for powersupply and amp-stage....

anyone got any suggestions?

http://www.hagtech.com/bugle.html

jackinnj · 17th March 2004, 03:28 PM

national has an RIAA phono amp based upon the LM833 chip on their website -- look it up on the LM833 product descriptor.

i was quite pleased with the results (but you could use a quieter chip if you so desire.) i looked for the PCB layout on my drive, but must have erased it.

kmj · 17th March 2004, 03:37 PM

thanks, but there was only the partial schematic.....

im not looking to buy a kit, only the parts and solder them together and put it all in a chassi (to make short summation )

much cheaper that way, and a kit feels like cheating......

kmj · 17th March 2004, 03:38 PM

national???

coffin · 17th March 2004, 03:55 PM

http://www.national.com/pf/LM/LM833.html#Datasheet

and this:

Check Out MY El Cheapo Phono Preamp!

kmj · 17th March 2004, 04:17 PM

thank you, coffin.

The el cheapo seems to be what im looking for.

could a PCB transformer be used instead of a torrodial?

how would a powersupply look in that case?

jackinnj · 17th March 2004, 07:06 PM

Quote:

Originally posted by kmj
thank you, coffin.

The el cheapo seems to be what im looking for.

could a PCB transformer be used instead of a torrodial?

how would a powersupply look in that case?

I use a small PCB transformer -- be careful to keep the a.c. line inputs away from the phono inputs. for the power supply I use a pair of LM317's and a pair of LM337's -- for the + and - rails.
the first regulator is set to 19 volts, the second to 15 volts -- the two regulators in series seem to prevent "turn-on" thump.

kmj · 17th March 2004, 07:37 PM

A friend of mine used this as a 15V supply....

with these:
U1,2: http://www.elfa.se/elfa/produkter/se/2021125.htm

trafo sec 2x15V: http://www.elfa.se/elfa/produkter/se/2014310.htm

could i use that and make it 2x12V instead using this:
http://www.elfa.se/elfa/produkter/se/7026.htm

just push the little brittish flag to change language on ELFA

Keld · 17th March 2004, 10:13 PM

Quote:

Originally posted by kmj
thanks, but there was only the partial schematic.....

The hole schematic is in the "User manual"

17th March 2004, 02:11 PM	#1
kmj diyAudio Member Join Date: Feb 2004 Location: Falkenberg	Easy DIY RIAA-preamp wanted. Hi, I am in need of a preamp for my old turnable. It seems that the guys at HK neglected to put a phonoamp in my reciever...... so instead of buying one i thought that i perhaps could start up a new hobby and build one myself. But since there are so many schematics out there i thought that you guys could recommend one thats quite easy to build and with complete schematics for powersupply and amp-stage.... anyone got any suggestions? imput sencitivity and impedance of the existing amp is 200mV and 47kOhm

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17th March 2004, 03:28 PM	#3
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	national has an RIAA phono amp based upon the LM833 chip on their website -- look it up on the LM833 product descriptor. i was quite pleased with the results (but you could use a quieter chip if you so desire.) i looked for the PCB layout on my drive, but must have erased it.

17th March 2004, 03:37 PM	#4
kmj diyAudio Member Join Date: Feb 2004 Location: Falkenberg	thanks, but there was only the partial schematic..... im not looking to buy a kit, only the parts and solder them together and put it all in a chassi (to make short summation ) much cheaper that way, and a kit feels like cheating......

17th March 2004, 03:38 PM	#5
kmj diyAudio Member Join Date: Feb 2004 Location: Falkenberg	national???

17th March 2004, 03:55 PM	#6
coffin diyAudio Member Join Date: Oct 2002 Location: Taiwan	http://www.national.com/pf/LM/LM833.html#Datasheet and this: Check Out MY El Cheapo Phono Preamp!

17th March 2004, 04:17 PM	#7
kmj diyAudio Member Join Date: Feb 2004 Location: Falkenberg	thank you, coffin. The el cheapo seems to be what im looking for. could a PCB transformer be used instead of a torrodial? how would a powersupply look in that case?

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