Simplistic NJFET RIAA

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Joined 2006
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Revamped the riaa filter.... replaced the 15n teflons by some small ICL, the russian polystyrenes (47n) replaced by the obbligato... simplified the resistors and now it really sings.

BTW, the russian polytyrenes are very good for bypassing "plain" mkp on the output and on the BiB vref.
 
diyAudio Chief Moderator
Joined 2002
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Only workable scheme is MM phono + pre-pre stage from the PDF versions. With those you can select direct to phono or through pre-pre. This is not a loop feedback phono so to can just set a loop gain switch for MM/MC with exactly the same PSU and 1st stage set-up. I.e. not behaving like a discrete op-amp.
 
Salas,
how to switch between MC or MM cartridges. Any switchable option for gain reduction ?

I suggest any switch at the cartridge signal input will degrade the sound (compared to if it wasn't there). So if your gain is MM only (40dB), it's best to use a head amp or SUT before the phono stage.

However, if your gain is up around 55dB (as my phono stage is), this will be able to handle most LOMCs and also MMs ... you just have to turn your preamp volume control up more, for LOMCs. (I use both my 0.28mV Benz LP and my 4mV Grado Reference Reference1 with my 55db phono stage.)

Regards,

Andy
 
I did something like that for a friend (long ago)... my build had two pairs of inputs, one for high output MC ~ MM and another for very low output MC.

I used a sut instead of the prepre

AIUI, having the 2 pairs of input RCAs (for HOMM & LOMC) means that the extra circuitry for the LOMC interacts with the circuit for the HOMM ... which is undesirable?

Sure, you may not have heard much of a difference - but, to do the comparison properly, you need to have 2 separate, almost identical phono stages inputting to your preamp ... one for the HOMM directly (without the extra gain stage for the LOMC), the other with the parallel LOMC inputs.


Regards,

Andy
 
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Dual inputs. one for MM and one for MC.
Then switch in the output of the MC pre-pre to the input of the MM.

Very few would have the need for a quickly swappable MC MM.
They may have two decks set up with alternative MC/MM. Two inputs would better suit this.

If one had only one deck and an arm that happened to suit both MM & MC, then a quickly swappable input is not required. A single input would suit this re-arrangement of the deck.
 
HF performance at the shunting current is important.

If a 510 would take the heat then provided it can be stabilised then it is likely to perform better.

But so much around the circuits interact with other components and parameters that I cannot predict which combinations will perform at HF.

I think it is the HF performance of these Salas Regs that gives them the good results that we hear.