Simplistic NJFET RIAA

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#3,302
I like that 10.79V. Now, is there one that will bring right channel over 10V? Because it looks that we can not match to the 9.4V right as a reference with those you got in hand. Keep exchanging on the right, we are heading somewhere good. Try No6 on right, as you are.
 
#3,304
Great! Leave them in. Now Ricardo will have a base. 3.3K sharp R1 load resistor for each channel. Its very important, because it reflects the output impedance of first stage. Now if you give it a listen, I expect it to be more focused. For the time being if you feel it is on the soft side too, take the extra caps out of C3's base value, it will pick up in the high mids and treble, until you will do your precise values and maybe resistor types fix with Ricardo. Let me know if it got better.
 
#3,307
Salas said:
Great! Leave them in. Now Ricardo will have a base. 3.3K sharp R1 load resistor for each channel. Its very important, because it reflects the output impedance of first stage. Now if you give it a listen, I expect it to be more focused. For the time being if you feel it is on the soft side too, take the extra caps out of C3's base value, it will pick up in the high mids and treble, until you will do your precise values and maybe resistor types fix with Ricardo. Let me know if it got better.
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Ok now Left channel 10.97V Right channel 11.14V. Taked out the extra caps of C3's now only 1 cap 15n6. Changed R1 trimmers in both channels for fixed resistor Xicon carbon film 3K3. Let me tonight to hear, tomorrow I will let you know.
 
#3,308
#3,310
Salas said:
Ricardo, Merlin, what is the spec precision of those LCR meters? Also was the non matched ''6k8'' 6.k9 or 6k79?
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Mine LCR can be adjusted with a pot, so when connect togheter + & - I adjust to get exactly 0.00 ohms, other way is check a very good resistor of a tigh tolerance 0.025% or 0.0025% I remember that I have one Vishay like this but now I don't know where is, is not a S102K was another cheaper sell in England I don't remember the series but was also bulk metal foil.

Non matched is: R4 Left channel 6k80 - Right channel 6k79
 
#3,312
Now you are really entering the fun part.

I started by fidling with C3 (16n) to get rid of some high freq proeminence, than I tampered with C2 (47n) to get more bass but found that I could easily loose "snap".

After that I found that lowering R4 (6k8) I could get loads of mid detail (around 1000kHz)

When I lowered R3, I discovered I could get much more overall body and presence.

After a very long period of trial and error experiments I put all the formulae in a spreadsheet and now I can really predict a good result based on the real values measured with a dependable LCR. (Math and spreadsheets are my core speciality) 🙂

With your actual values I would certainly bypass R3 with some 1Mx values ... That will bring loads of presence increasing bass and trebble a lot so I would keep C3 at 16n (under 16n the sound will become edgy).

But you need to increase C2 (between 450p 470p) so you do not loose "snap".

Let me know how it sounds after this.
 
#3,313
PS... It was that long period of trial and error that I changed my avatar to the actual Franz idea of an adult suffering from sound agression 🙂

Now I am listening to an humble P3 with DL160 sounding like a real piano.
 
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#3,314
Checking against some reference resistors, say in 3 value scales would show. But they normally are more tolerant for capacitors. Do you have a capacitor measured on some expensive and calibrated bridge so to check? So after that will know exactly what we are after when calculating tight.
 
#3,315
RCruz said:
After a very long period of trial and error experiments I put all the formulae in a spreadsheet and now I can really predict a good result based on the real values measured with a dependable LCR. (Math and spreadsheets are my core speciality) 🙂
Click to expand...

So you made a spreadsheet especially for the Simplistic based on subjective trimming of the Riaa values? Amazing.:hypno2: That's a lot of work. And it works for all sensitivity ccts? What about when changing VTA or preamp? Does it still work better?
 
#3,318
Salas said:
Checking against some reference resistors, say in 3 value scales would show. But they normally are more tolerant for capacitors. Do you have a capacitor measured on some expensive and calibrated bridge so to check? So after that will know exactly what we are after when calculating tight.
Click to expand...

Well to be sure better send the LCR to Farnell or Applus or other company to calibrate or better to buy a real proffesional machine like this:

DIGIMESS|RLC300|MULTIMETER, DIGITAL, LCR, 0.1% | Farnell España

An externally hosted image should be here but it was not working when we last tested it.


Well as said my mother "dream don't cost money"

But for me the measurement is a 1st approach, I decided do the final tuning by hear like mine friend Ricardo do😉
 
#3,319
Salas said:
So you made a spreadsheet especially for the Simplistic based on subjective trimming of the Riaa values? Amazing.:hypno2: That's a lot of work. And it works for all sensitivity ccts? What about when changing VTA or preamp? Does it still work better?
Click to expand...

There is still room for improvement but now I can predict the effect of very slight changes in the riaa eq components without the need for long listening periods.

IMO the correct values are much more important than the quality of the components (A finetuned riaa with silmic sounds much more spacious than a poorly tuned one with fullon BG build). For example you can easily loose mid freq detail just by an error of 40ohm on R4(6k8r) and you can loose bass snap by an error of 50p on C2 (47n))

VTA changes are more effective now.... I did not have the oportunity to try another preamp but I have now the same degree of sumptuousness in all my three different gain builds.
 
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