Mpp - Page 767

Algar_emi · 11th November 2012, 02:34 PM

Finally had time to start to assemble my Paradise preamp boards. Both shunt supplies section are working fine. I tested them using a simulated preamp load, and was able to check my pre-reg and rc-filer small pcb as a complete circuit. That confirmed that the pre-reg pcb is ok, and with the specified parts, the RC filter drop resistor gives me 26.5V at the input of the preamp insuring that the shunt heatsink is not too hot. I'll continue the assembly of the preamp.

Joachim Gerhard · 11th November 2012, 02:37 PM

That looks great !

mkoerner · 11th November 2012, 03:57 PM

And would even look better in the Builder Thread ?!

Algar_emi · 11th November 2012, 05:21 PM

What is the recommended IDSS value for the 2SK170 used in the circuit?

Joachim Gerhard · 11th November 2012, 05:24 PM

Around 8mA. It can be higher. That value gives the range where the JFet works in class A
( aprox. ), so 8mA give you 80V dynamic range into 10kOhm, that is ample.
Into 1kOhm that transfers into 8V, still enough.

FdW · 11th November 2012, 09:02 PM

Quote:

Originally Posted by Algar_emi

Finally had time to start to assemble my Paradise preamp boards. Both shunt supplies section are working fine. I tested them using a simulated preamp load, and was able to check my pre-reg and rc-filer small pcb as a complete circuit. That confirmed that the pre-reg pcb is ok, and with the specified parts, the RC filter drop resistor gives me 26.5V at the input of the preamp insuring that the shunt heatsink is not too hot. I'll continue the assembly of the preamp.

Very nice

very nice, high five - YouTube

Algar_emi · 11th November 2012, 09:40 PM

Installed all the preamp parts, all matched per sections. Here my readings, I'll check the RIAA curve accuracy this evening. Since everything is well balanced, I guest it is working fine.

Supplies +/-18V, 150ma ea

TP3= +14.5V TP5, 6= +16.36V
TP4= -14.5V TP9,10= -16.36V

Each Gain Cell transistor, each emitter resistor V=115mv (3.5ma each)

Vin = 0mv (adjusted with R1)

Vout: DC offset keeps changing around +/-25mv

Gain: 61.4dB at 1Khz
Vout max: 30Vpk-pk

Joachim Gerhard · 11th November 2012, 10:31 PM

That looks good. DC offset will go down after a while i think.

Joachim Gerhard · 11th November 2012, 11:28 PM

I added a line input to my smallest preamp called " Das unbeschriebene Blatt" ( The Blank Page ). It has DIN A4 proportions. The cables go in from the top.

Joachim Gerhard · 11th November 2012, 11:30 PM

In the backround you see a phono stage
called " Stille " ( Silence ) i prepare for the Vienna Klangbilder show.

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11th November 2012, 02:37 PM	#7662
Joachim Gerhard diyAudio Member Join Date: Mar 2009	That looks great !

11th November 2012, 03:57 PM	#7663
mkoerner diyAudio Member Join Date: Jul 2012 Location: The home of Porsche, Daimler, Bosch etc	And would even look better in the Builder Thread ?!

11th November 2012, 05:21 PM	#7664
Algar_emi diyAudio Member Join Date: Oct 2002 Location: Canada, Qc	What is the recommended IDSS value for the 2SK170 used in the circuit?

11th November 2012, 05:24 PM	#7665
Joachim Gerhard diyAudio Member Join Date: Mar 2009	Around 8mA. It can be higher. That value gives the range where the JFet works in class A ( aprox. ), so 8mA give you 80V dynamic range into 10kOhm, that is ample. Into 1kOhm that transfers into 8V, still enough.

11th November 2012, 09:40 PM	#7667
Algar_emi diyAudio Member Join Date: Oct 2002 Location: Canada, Qc	Installed all the preamp parts, all matched per sections. Here my readings, I'll check the RIAA curve accuracy this evening. Since everything is well balanced, I guest it is working fine. Supplies +/-18V, 150ma ea TP3= +14.5V TP5, 6= +16.36V TP4= -14.5V TP9,10= -16.36V Each Gain Cell transistor, each emitter resistor V=115mv (3.5ma each) Vin = 0mv (adjusted with R1) Vout: DC offset keeps changing around +/-25mv Gain: 61.4dB at 1Khz Vout max: 30Vpk-pk

11th November 2012, 10:31 PM	#7668
Joachim Gerhard diyAudio Member Join Date: Mar 2009	That looks good. DC offset will go down after a while i think.

11th November 2012, 11:30 PM	#7670
Joachim Gerhard diyAudio Member Join Date: Mar 2009	In the backround you see a phono stage called " Stille " ( Silence ) i prepare for the Vienna Klangbilder show.