Sorry to disturb again Nick, I do a mistake writing mi 2SK170BL njfet stash, I have:
2 x 8.16
1 x 8.71
1 x 8.80
1 x 8.88
1 x 8.98
Wich Idss for Q5?
2 x 8.16
1 x 8.71
1 x 8.80
1 x 8.88
1 x 8.98
Wich Idss for Q5?
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For Q5 whatever from your 6-7mA ones will do fine. Use the 8.80 & 8.71 for 2nd stage since you haven't got exact pair, their gain should be the same although they will bias a bit differently.
You could not do differently anyway, and they will work. Stop the confirm, confirm and start the build, build. 😉
Now I'm testing with 15.33nF RIAA cap, first impressions is the sound is more equilibrated over all audible bandwith.
I also found that bypassing the output caps can make a big difference.
I would not bypass expensive caps like the good Mundorfs or Duellunds but all other MKP deserve this attention.
After long experiments with small valued Auricaps, FT-3, polystirenes and SM I found that the obligatos like small obligatos.
In this case 4u7 // .047u did the magic.
In the shunts, the low cost Audyn is bypassed by a small 10pF SM. This opens up the sound producing much more explicit highs and tighter well defined lows.
These Audyns are very close to the Mundorfs MKP and respond as well to the bypassing act.
I would not bypass expensive caps like the good Mundorfs or Duellunds but all other MKP deserve this attention.
After long experiments with small valued Auricaps, FT-3, polystirenes and SM I found that the obligatos like small obligatos.
In this case 4u7 // .047u did the magic.
In the shunts, the low cost Audyn is bypassed by a small 10pF SM. This opens up the sound producing much more explicit highs and tighter well defined lows.
These Audyns are very close to the Mundorfs MKP and respond as well to the bypassing act.
Attachments
What cap are you using ?
I found that a full SM combination brings more detail and snap but needs adjustments to get the high bass up a notch.
Using Tin Foil polystyrenes produces a bigger fuller, nicer presence but somehow lacks the high freq bite.
no, no foil is connected to casing. works very well with green rusky pio's (paint removed a bit), little harder to measure mbm and k73-k75
It looks like such a simulation cannot be fully accurate, since, at least, it doesn't take into account stray capacitance in the circuit. Which is one more reason for listening tests being indispensable.
This is not intended to be accurate.
It represents the possible deviations (errors) from perfect riaa setup.
I compared the results against proven Salas setup.
In this case (48dB) C2 is 15.33nF and R1 is 47kr.
I just wanted to show what error each component might introduce and how.
I am not suggesting anyone should deviate from Salas schematic but I agree that sometimes it is important to tune these components by ear and this graph gives a visual idea of what to expect.
Lowering the 15n cap introduces a rise in responce from 1000Hz onwards.
(A very small change "10pF" can be clearly heard)
Lowering the 47kr produces much dramatic effects in the power band.
It represents the possible deviations (errors) from perfect riaa setup.
I compared the results against proven Salas setup.
In this case (48dB) C2 is 15.33nF and R1 is 47kr.
I just wanted to show what error each component might introduce and how.
I am not suggesting anyone should deviate from Salas schematic but I agree that sometimes it is important to tune these components by ear and this graph gives a visual idea of what to expect.
Lowering the 15n cap introduces a rise in responce from 1000Hz onwards.
(A very small change "10pF" can be clearly heard)
Lowering the 47kr produces much dramatic effects in the power band.
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I come back to R9 100R + C5 470uF & the mids come back so wasn't RIAA cap problem, I have 1Meg in parallel with 47K could you similuate the best C3 RIAA cap value for my phono preamp?
Thanks in advance Ricardo
Thanks in advance Ricardo
Hi Merlin
For C3 I believe you are talking about the 15.33nF cap right ?
Acording to Salas revised pdf, for 43~48dB you should use 15.33nF
For higher gain, you can use 15.10nF.
I am using those values and tuned the results on the shunts vref and output caps... but I am not using special caps there so the results are different and depend on the rest of the components choices.
The most important components are R4 and C2 that form the 500.5Hz turn point.
I can run your setup in my simulator but I need to know all the values of the resistors and caps you are using on the passive riaa filter.
For C3 I believe you are talking about the 15.33nF cap right ?
Acording to Salas revised pdf, for 43~48dB you should use 15.33nF
For higher gain, you can use 15.10nF.
I am using those values and tuned the results on the shunts vref and output caps... but I am not using special caps there so the results are different and depend on the rest of the components choices.
The most important components are R4 and C2 that form the 500.5Hz turn point.
I can run your setup in my simulator but I need to know all the values of the resistors and caps you are using on the passive riaa filter.
Yes, I'm refering to this schematic, I'm using the same values except R3 47K bypassed with 1Meg, I have exactly 47nF what happens if I increase or reduce the value? could you post the simulation?
