Anyone built the phono pre from LM4562/LME49720 datasheet?

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Tolu

Tolu

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Joined 2007
I am talking about this schematic!
 

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ahaja

ahaja

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Joined 2004
>Tolu
Yes, exactly.
I changed the gain to 45dB.
Pre stage (MC LO) in front of this schematic gives me 25-40dB (variable - dip switch). Is very quiet. Yoy can also add Neumann time constant.

I tried a few years ago Bugle preamp. Sounds soft compared to this from datasheet LME49720. And is more, more noisy - I left it because I coudn't enjoy with MC LO.

K
 
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Artie

Member
Joined 2007
I hope no one minds if I revive this topic, but its right in line with my question. (Two questions, actually.)

1. I don't really understand why this is called a "passive EQ", since it obviously has two major active components in it. What am I missing here?

2. The same data sheet also has two other RIAA circuits. What are the advantages of one over the other?

These same three RIAA circuits are contained in several of the National LME series IC's data sheets.

Thanks all.
Artie
 
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spgjmf

Member
Joined 2008
I just finished a lm4562 riaa preamp...love it. simple and sounds smooth and even. nothing jumps out, well balanced I think. gave up for now on the simple jfet designs, could not get matched fets working...I wanted to listen to records, so went the easy way with opamps...

Jeff
 

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ahaja

ahaja

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Joined 2004
Hola

Sorry, but I've lost my eagle files, so I draw it from memory :).
It looks sth like this.
I added var gain for MC LO and for MM carts. I wanted to do preamp for many different carts ... and it plays very good. No matter if I listen Ortofon SPU with Replicant styli or cheap Goldring or another Ortofon MM series.

Krzysztof
 

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FdW

FdW

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Joined 2009
Yes, I did (build the NS AN version), but I changed the gain to match the ADC exactly, and I also changed the input configuration to balanced. Before I did make the final build a balanced and a unbalanced version was build and compared, we (me and my friends) (using a pair of Sumo 10M class a mono blocks, Carver Amazing Platinum loudspeakers, Thorens 160b, SME 3009, Shure V15VxMR) found the balanced version sounded ‘faster’ and ‘cleaner’. Have a look at this thread for pictures of the finished product: http://www.diyaudio.com/forums/digital-line-level/35621-diy-adcs-4.html, it also has a sample audio file.

Regards,
Frans.
 
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defec

Member
Joined 2004
Hi, I built the RIAA circuit in the LM4562 data sheet and the output isn't enough for my system. Can anyone tell me what resistors to change to raise it etc? I think it's the first 150ohm resistor but I'm not sure if the second 150ohm also needs replacing and how to arrive and what value to use. I'm using moving magnet carts but my preamp is unity gain so I need a bit extra I guess to get it to the other source levels.

Tolu posted the schematic on post #4 of this thread. Any help is greatly appreciated.
 
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