LM833 any good?

[carlosfm]

Re: jfet phonostage power supply

Hi Carlos,
Could you post a schematic of the power supply you used with the phono stage.

Thank you,
Ray Simmons

I'm using batteries.
3 x 12V/4Ah SLA in series.

 

[thalis]

I suspected this, Carlos ;-)

Raysimmons, if you would like to do it solid state, I believe you can get good results with a classic LM317 circuitry for instance.
Note that if you would like to have a MC phono, you can add another similar SK170 stage in the input with a gain of some x10 (in which case bear in mind that you get an inverting output) – the noise can be still acceptable, well below the disk surface one, without having to parallel fets.
Regards.
Thalis

 

[carlosfm]

I suspected this, Carlos ;-)

Raysimmons, if you would like to do it solid state, I believe you can get good results with a classic LM317 circuitry for instance.

That's right.
Ray, take a look here:
http://myweb.tiscali.co.uk/nuukspot/decdun/gainclonepre2.html

If you join the unregulated PSU schematic (RCRC) with the PSU circuit on-board on the preamp schematic, from input to the C3 cap, you have an LM317 regulated PSU, which you can use here.

 

[RAYSIMMONS]

Thank you ,
Carlos and Thalis I will try both implementations(battery and solid state) this weekend.

 

[AudioEngineer]

Another Q

Would it be better to put a buffer before and after a vol pot?
Rather than just after?

Adding extra op amp stages only add more noise and distortion in the circuit. Only use them if you feel it is justified. You would only need a buffer before the volume control if the output stage just before the volume control is unable to drive the load of the volume pot with the desired low distortion figures. Since National show in their datasheet the Gainclone ICs can use a 10K pot for the input there wouldn't be any need for a buffer stage after the pot. I think its more important you use a 10K pot rather than a higher value one as a high value pot could cause a high frequency roll off. If you are wanting to provide a low source input to the amplifier stage then use a 5k pot and make sure the stage before the pot can drive it with the desired distortion figures, and if necessary put a buffer before the pot.

 

[mondogenerator]

I have used both 833 and 5532 in rectifier circuits feeding a LP for RMS to DC conversion.

For some reasons i don't understand, the 833 was better for the rectifier stage, very stable, where the 5532 oscillated slightly around zero volts.