RIAA passive filter values.

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kodabmx

kodabmx

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Joined 2011
I'm thinking of building the reference RIAA design from page one of the datasheet for the LME49720.
I have the following filter parts available.

I don't see any problem with substituting the following filter instead, but I thought I'd ask the community.

Anyone think this op amp will have any issue with the slightly lower Z?

Thanks.

EDIT: C4 and R10 were in the original design I used with tubes, and I know they can be omitted.
 

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jackinnj

jackinnj

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tech-diy.com
I love the passive RIAA, but one thing to be aware of is that peak signals, particularly on the outer grooves of a recording tend to be "hot". The illustration below is from a Shure whitepaper on trackability but illustrates how much energy you have to deal with.

So, don't skimp on the rail voltages if you want decent headroom.

LME49720 and LM4562 are (or were) identical devices. The max rail voltages in the datasheets for some reason are different.
 

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kodabmx

kodabmx

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Joined 2011
Ok. Here's my preliminary design. I will power it from 2 9V batteries initially.

Out of curiosity, How would I transition this to a single ended power supply and a rail-to-rail output? I know the LME49720 won't work, but how about an AD823ANZ? I assume I just need input and output coupling caps?

Thanks.
 

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kodabmx

kodabmx

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Joined 2011
PRR said:
Why not???

No ordinary op-amp has a dedicated ground pin; that went out of style in 1963. All opamps can be run single-supply.

But you need more than in/out caps....
Click to expand...

Because from what I have read the rail to rail op amps can swing their output below ground.
"The AD823 is a dual precision, 16 MHz, JFET input op amp
that can operate from a single supply of 3.0 V to 36 V"

in any case, it was just an exercise. No real reason not to use dual voltages. Unless you wanted to run it from a single 9V :)
 
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PRR

PRR

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Joined 2003
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kodabmx said:
...from what I have read the rail to rail op amps can swing their output below ground....
Click to expand...

:eek:

At TA = 25°C, +VS = +5 V, RL = 2 kΩ to 2.5 V, unless otherwise noted.
OUTPUT CHARACTERISTICS
Output Voltage Swing
IL = ±100 μA - 0.025 to 4.975 V
IL = ±2 mA - 0.08 to 4.92 V
IL = ±10 mA - 0.25 to 4.75 V

Some milliVolts *above* ground/V-.

Ah:
"It has true single-supply capability with an input voltage range extending below ground in single-supply mode."
 
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SyncTronX

SyncTronX

Member
Joined 2008
Do we know if the op has identifed the type of cartridge?
Such as a Moving Coil (MC) or Moving Magnet (MM) cartridge,
each with different requirement's I'm told?

I didn't see any mention of cartridge in the thread, that is why I ask.

Isn't it possible to taylor a design to a cartridge type and a specific
cartridge? Do we have to consider anything of the various cutting head
types when they made LPs and if there are any issues outstanding?

I assume that is device is only one LMC49720 using the "a" half

and the "b" half for one channel?


Cheers
 
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