MC Riaa preamp help/opinions please

[duderduderini]

Thanks to all for advice.. i added some more filtration and wired according to audioexpress article re motorboating. Since this is a prototype i at least have prooved its possible but.. need to work on hum, get a regulated ps and figure out riaa.. apart from that everything is dandy!!!!
To EC.. i mistook your id for ec designs who has made a dac for cd player.. i apologise.
If anyone can enlighten me on how to figure riaa then feel free as i think bobs original octal phono amp has now been added to such that it doesnt seem to work well anymore (the sound is shall we say devoid of any bass)
Thanks to all of you
Nick

[EC8010]

Originally posted by duderduderini
To EC.. I mistook your id for ec designs who has made a dac for cd player.. I apologise.

No worries.

PS Do Australians really say that, or is it just another cultural myth?

[duderduderini]

Thanks EC
What are we meant to say?
Nick

[duderduderini]

I would say a lot do actually. Generally its "no worries mate" but any abbreviation will suffice.
I hope this lesson in the intricacies of the australian myth encourages you to visit EC.. just bring lots of 500V caps and non inductive wirewound resistors when you do.... oh and transformers
Regards
Nick

[EC8010]

Yes, I had heard that you are short on transformer winders. Of course, you can always recycle mains transformers if the laminations haven't been varnish impregnated. First unstack the core. The mains winding is always the inner winding, so count the secondary turns as they come off to find the voltage to turns ratio, measure the wire diameter to find the current density, and then you can rewind for any voltage.

Non-inductive W/W only seem to be readily available in the USA, and 500V electrolytics are fragile things.

I'd quite like to visit Australia and New Zealand but the long haul flight puts me off.

[Sheldon]

Originally posted by duderduderini
Thanks to all for advice.. i added some more filtration and wired according to audioexpress article re motorboating. Since this is a prototype i at least have prooved its possible but.. need to work on hum, get a regulated ps and figure out riaa.. apart from that everything is dandy!!!!
To EC.. i mistook your id for ec designs who has made a dac for cd player.. i apologise.
If anyone can enlighten me on how to figure riaa then feel free as i think bobs original octal phono amp has now been added to such that it doesnt seem to work well anymore (the sound is shall we say devoid of any bass)
Thanks to all of you
Nick

You can check your RIAA values with this calculator: http://www.hagtech.com/equalization.html You'll need to parallel the Rp of the tube with the plate resistor and add that to the RIAA series resistor, then plug those values into the calculator. The first section in your schematic is the 2122 pole, and the second is the 50/500 Hz turnover. You don't have a treble zero at 50kHz, but you could add one. This should let you know if the values are in the ballpark.

Sheldon