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Old 11th December 2011, 09:22 PM   #3391
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Thanks Frans, Your circuit is what i was dreaming about : simple and very good. Honestly, i am not a good PSU designer so this help is much appreciated.
Rüdiger, a transconductance balanced Paradise Lost with J-Fets is easy. You can parallel more for less noise if you wish. The transimpedance gives me a bit of headache. I think AC coupling is no problem. Does anyone have a better idea ?
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Old 11th December 2011, 09:25 PM   #3392
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Default Starless (Sampler´s Version)

Hi Joachim

I have some questions about Your Starless design (Sampler´s version) and would really apreciate your input.

I sent you a PM in order to avoid off topic conversations here
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Old 11th December 2011, 09:25 PM   #3393
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Rüdiger, this is a rough skcetch. Values may change. I trust on MiiB to find the right conditions.
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Old 11th December 2011, 09:36 PM   #3394
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Ricardo, i see you have attatched the circuit already-
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Old 11th December 2011, 09:55 PM   #3395
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Ricardo, i do not know if i invented that stage but i have not seen that before. Q1, Q2, Q15
can not be without Q9, Q16, Q10 because that establishes zero volt DC at the cartridge when Idss are matched. You can see the same principle in the simple EUVL I/U converter.
I casoded the input Fets with floating Fets of higher Ugs for better performance. The mirrors allow DC coupling into the RIAA but need a conventional plus-minus supply. EUVLs arrangement allows a floating supply with some advantages but needs a big elcaps to couple out. The mirrors output impedance supplies current into the RIAA that then shapes the frequency response by shunting more and more current to ground when frequency goes up. That also has the curious effect that distortion goes lower when frequency go up. This is the opposite of NFB around and OPamp and may be the single most important reason a circuit like this sounds different. The output is a Salas DC B1 buffer that has a cap in front. 10nF give a slight subsonic filter under 25Hz. You can experiment with bigger caps. I think Sampler´s new version has a 49nF. That depends how good your turntable is down there. If you have a miss match of compliance and arm mass or some rumble the subsonic filter may sound better. There is no resistor at the input because the cartridge load alone does the job. You could put a 100Ohm from input to ground to avoid switch on transients when you switch the cartridge with the stgae under juice.
Well, actually the RIIA made active with an Opamp assures at least that the distortion does not rise much in treble but it definitely does not go down with frequency.

Last edited by Joachim Gerhard; 11th December 2011 at 09:59 PM.
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Old 11th December 2011, 10:11 PM   #3396
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Thank you so much for the lightspeed answer.

I see I was not completely wrong in my assumptions and you made it pefectly clear now.

I must digest this and try to understand the connections between the cart and Q1 Q2 and Q15... after that it will be a blast
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Old 11th December 2011, 10:24 PM   #3397
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Ricardo, you understood it pretty well. The cartridge simple modulates the source of the Fet against ground.



That is very similar then a BJT common base stage. This is a common gate stage instead that allows DC coupling.
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Old 11th December 2011, 10:27 PM   #3398
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Common gate - Wikipedia, the free encyclopedia
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Old 11th December 2011, 10:39 PM   #3399
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Internet is a marvel and life is good.

I must rest now because tomorrow I will take my kid to school early in the morning
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Old 11th December 2011, 10:41 PM   #3400
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Take care.
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