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lt cdr data 20th April 2005 09:39 AM

shucks...
 
no-one has replied yet to my first post.

I will phrase it again..

I want to use lt1028 with a passive riaa for an mc phonostage design, but want to use a dual opamp for the output stage.

I am a bit new to this, so could some wiser person please inform, and yes I have done a lot of reading, its all a bit of a muddle...

what are the requirements for the first opamp in a phonostage i.e. is noise the most important?

and I really need recommendations for dual opamps for the 2nd stage, the 2nd will be an output stage with gain, so presumably we need
something load tolerant.


as a by the by some extra info I could do with..

noise...voltage for mc, load resistor, feedback resistor, this I am fairly ok with.

riaa...pros cons of passive v active, which filter you should place where for a split riaa

overloading, explanation needed.

bandwidth of chips

anything else?

all this info in an easy to digest form is REALLY hard to come by, any help greatly appreciated, thanks, John.

SY 20th April 2005 10:52 AM

Step one- what cartridge is anticipated? Step two- direct in or via transformer?

Low noise is definitely the major requirement of the first stage, but which opamp is optimal in that regard depends on the source impedance of what's driving it. I don't have the National Semiconductor applications book on me at the moment, but I'm sure it's up at their website- they have some great app notes on the relationship between current noise, voltage noise, and source impedance. Very worthwhile reading.

scott wurcer 22nd April 2005 12:56 AM

Quote:

Originally posted by SY
Step one- what cartridge is anticipated? Step two- direct in or via transformer?

Low noise is definitely the major requirement of the first stage, but which opamp is optimal in that regard depends on the source impedance of what's driving it. I don't have the National Semiconductor applications book on me at the moment, but I'm sure it's up at their website- they have some great app notes on the relationship between current noise, voltage noise, and source impedance. Very worthwhile reading.


That would be AN-104 (free download), if you go looking for the book there is only a reprint that sells for $15 or so.


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