Simplistic NJFET RIAA

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nicoch46 said:


my supravox don't do :) thorsten L. project....

No drooping & beaming HF? Its a rather large bicone fullrange, isn't it?

Anyway, was talking in a general scenario, I don't know more about any system specifics and individual room sound, If I really haven't measured and experienced it. The loading thing is always open to change for best overall match. When you make it, you will find its best balance for your specifics. Never afraid to change parts quality and loading conditions or gain to hit equilibrium. Waiting for your results. Best of luck with new TT, carts, & tweaks!:)
 
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Surely very natural sounding choices, I just think that the upper harmonics spread that I get with high value resistor loading on the Denon might be complimentary to your speakers, more than mine. So this might explain our different loading choices.
 
need try your phono....

with supex 80ohm ,(better cartrige) at 23.5k sound more worm-balanced but the soundstage remember the dl160 at 3k,a little not expanded ..need to try new RL tomorrow

I prefer the dl-160 at 3k for HF balance , but at 23,5k for big soundstage with a little HF evidence


difference :
FR>boxy=vinyl>cd
 
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I just saw your project

Hi Salas,
Nifty project. I may put one together for my Ortofon 540 and Thorens TD-126 MKIII.

May I ask if the 5 dB lift between 10 and 20 KHz is the Denon cartridge, preamp or test record? That would be very noticeable I would think.

-Chris
 
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Hi, thanx.

That last octave bump is common to MC with very few exceptions that they push it an octave higher, alas with a somewhat droopy response.
Its the tip mass - record surface resonance. There are bumpier than that! Not that noticeable given the lossy nature of many vinyl recordings and our ears. Plus power response of tweeters not usually strong. Get the VTA ok not to push it if with MC.
With MM the tip mass is higher, and the compliance higher normally, so other things usually mask it from prominence. Since your cartridge is MM with 200-400pF recommended load, I would urge you to avoid the above versions that produce 300-400pF Miller. Think that your cable may be 100-150 or 200pF additionally. Make the MM cascode version that I attach, with suitable gain, suitable overload margin, and very low Cinput. You may not attach at all the 100pF typically shown and start listening with just your cable capacitance, adding some Siver Mica for comparison. I have concluded that is the best sequence with MM. Or simulate what its inductance does with 47k and measure your cable pF to add. Then you know what you will need. You will not want to drive anything less than 30K line input or add a JFET buffer (better avoid if over 30k).
 

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Hi Salas,
Duh!! Brain fart on my part.

My cartridges are all replaceable stylus and high output. Someone did ask me recently about an MC preamp, so I mixed them in my mind. I haven't a clue what my acquaintance is using for a cartridge, or table for that manner. I think your circuit will solve his problem.

I would be driving an MM stage, or installing a buffer and run into a high level input.

Anyway, looks like a nice little circuit. Maybe not the best but probably better than a lot of things out there.

-Chris
 
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OK then. Here is your buffered version. From MM cartridge to line in. Can deliver up to 10mA to load. Lowest recommended is 20k with Cout 3.3uF. Make it 6.8uF for 10k load.

P.S. Don't drive an MM stage with 200-300mV that my 36dB stage and your cartridge will do. Sounds terrific for the little effort. A no brainer.;)
 

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Hi Salas,
This circuit will be amplifying a real MC cartridge, thank you. Your buffer is about as simple as it gets. I imagine that will drive most inputs with little trouble.

Don't drive an MM stage with 200-300mV that my 36dB stage and your cartridge will do.
Nope. Didn't intend to. The Ortofon drives a MM input just fine, but this opens a possibility to use a preamp with no phono input.

Thank you very much Salas.

-Chris
 
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You will need 61dB for 0.2mV MC, 55db for 0.5mV MC, 40dB for 2-2.5mV high output MC like Denon 110-160 or Benz Micro MC Silver or Benz Ace Blue, 36dB cascode for 3.5mV MM.
All the versions are covered in the thread, and all are capable of driving a line stage. I recommend to avoid the extra buffer stage if the line input load has impedance (Z) over 10X the 2nd JFET's Drain resistor. Keep it simple.
Of course if it is made for a 3rd party, then the buffer is adequate since you will not always know with what is going to be connected, or future changes. The 2 stages sound great if the output is under 300mV and the load right. The added buffer will cloud it just a wee bit, but it will save the day by keeping the distortion very low and the drive strong in any adverse situation.
 

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Re: Currently under test

salas said:
Plays very well with a finely tuned balance between full detail and no hardness at all. It is surprisingly dynamic even with low out MC (0.25mV). No noise. The local R-C decoupling of the first stage B+ for each channel is very audible. Focuses it. Batteries in general are good for noise but relatively Hi Z. Without the 10.000uF on their poles and the local JFET decoupling they create wide band interactions. I used 3X 12V 1.5Ah rechargeable batteries in series. I used Russian Silver Mica, Russian Polystyrene, Panasonic Electrolytics, & common metal film resistors. The 100R gate stoppers are Kiwame and optional. The output caps are Mundorf Supreme Silver/Oil. They were chosen as 0.68uF to create -10dB @ 5Hz to battle record warp. This is when they feed the 50K input resistance of the following Salas 6V6 line stage.

The black thing attached is the schematic. It will turn white when you click.:clown:

Hi Salas

I followed this link http://www.diyaudio.com/forums/showthread.php?postid=1628754#post1628754
and found your wonderfull work.

I will implement this with a PSU using superregs instead of batteries !

What should be the minimun voltage to feed your design ?

I am using a Benz ACE Medium output (Clear body)... should I make some adjustments or your design is good for this cart?

Please be pacient with me (I am no electronics wizz)... but in time I will surelly build this RIAA stage.

Best regards

Ricardo