Simplistic NJFET RIAA

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OK,
I am winding up things chassis-wise. Here are a couple of teaser photos. I will post some more in a few days.

First learning experience: I had a bolt through the toroid trafo that touched the chassis. (I've never used a toroid before.) Had a 20 volt difference between circuit ground and safety ground. I'll get a nylon bolt.

Dumb question: where can I hook an indicator LED without messing up the circuits? The resistors I have in the raw PS drop less than a volt.

Thanks. More to come.
Doug

Nice case work. Hook the LED across a rectification filter cap with a protection resistor good for 1mA so it shines mildly. (Vcap-VFled)/R=ILED
 
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Hi Salas,
Can you post it your best riaa for my shure V15 III, with dedicated shunt regulatore schematic?
Many thanks a Merry Christmas.
Mario

That's a 3.5mV cartridge so use the HighMC/MM from post #4945 pdf guide with an R2 value of 47R for 41.5dB gain. Folded version in this circuit is not optimal for MM level due to various technical reasons.
 
Seasons Greetings

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Hi Salas

I am now starting to focus on the 48dB build update.

I will convert it into a folded cascode input but would like to keep the riaa untouched because it is so good as is.

The problem is first stage load resistor that in the "normal" version is a 3k3r and in the folded should be 2k2.

One solution would be to increase riaa 47k with a 1k1r but I am not sure....

Can the folded cascode be moded to acomodate a 3k3r load resistor ?

I will use the specified 35v shunt because I have enough headroom.... Mains in Switzerland are more like 230vac than 220vac :)
 
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Certainly better to fix the Riaa bridge resistor value if needed than to unsettle the load resistor. Has impact on the input stage current balance.
Mains around 230VAC here too. Most of the time a bit over even.
 

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Onasis was calling her a "microphonist" whenever he wanted to make her furious according to an old well-groomed guy that he claimed was original Olympic Airways top flight attendant I chatted once with. :D

Haha - what an insult!! ;) ("microphonist"!) If she hadn't been trying to get him to marry her, I guess she could've called him a "tramp steamer owner"! :D

Regards ... and have a great NY,

Andy
 
diyAudio Chief Moderator
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Onasis was a cheeky materialist that loved to challenge established values of his time.
His beloved singer was Kokotas. He even gifted a custom Lambo Miura to him. Kokotas was a mean driver, he even competed in circuit events. So you get the picture. The paradox is not why Onasis was mocking, but why many greats were flocking after him.;)

onassis-kokotas.jpg
 
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Hi Salas

I am not sure about what value should I use for R11 on the folded.

Inittially you posted 1k6 for 8mA Idss on the buffer, then you updated the choice to 1k5 if Idss was 7,5mA.

But in the building guide you have 1k8 for 8mA idss.

I am using 8.5mA devices.... what should be the best choice ?
 
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Which ever leaves you with double the voltage across the buffer of what the second stage's load resistor to ground voltage is. The 300 Ohm span you noticed among some designs has to do with their specific test idss and/or one of those had a cascode fet extra.