Easy DIY RIAA-preamp wanted.

[kmj]

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]

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]

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]

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]

national???

 

[coffin]

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

and this:

http://www.diyaudio.com/forums/showthread.php?threadid=25813

 

[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?

 

[jackinnj]

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]

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]

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

The hole schematic is in the "User manual"

 

[maylar]

I'm going to use this one: (1 channel of 2 shown)

An externally hosted image should be here but it was not working when we last tested it.

edit: Oops - just noticed pins 2 + 3 are reversed. Sorry.

 

[coffin]

Regulator

Hi
Try this.

cheers

Coffin

 

[jcx]

for a first diy project you might want to avoid line power (esp european 230 VAC)

a pair of 9V alkaline batteries should last several days cont powering just 2 op amps

in the US i know many "wall wart" linear supplies are isolated from line/gnd so 2 "12 VDC" @ < US$ 5 ea could be a simple +/- 12 V supply

too many multi output supplies are switchers nowadays but some linears with +/-12 can be found for less than you can buy the parts - additional local RC filtering internal to your box could clean them up some

RC modelers use NiCd packs that are relatively cheap and I belive that NiCd can be indefinitely "trickle charged" so if your average use duty cycle is low enough this is a very simple and high quality option (the "on" switch disconnects the charger and connects the op amps)

 

[kmj]

Keld:
HOW could i miss it😕


now i've got a lot to choose from. But thanks alot everyone!