Same beta class is more than enough. Just make sure you trim the pot to cancel the input current. It can be done down to 20nA.
Thank you. I think that HPS-4.0 pcb PT holes are not wide enaugh for TO-126 transistor leads.
Does anybody know the types, distributor and catalogue number of the smaller PCB heatsinks used in HPS 4,0 and 4.2 phono preamps?I have decided to do a PCB for the raw power supply (rather than using perf board and wiring). See the attached pictures.
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Please give me an advice!
I don't have enough knoledges about transistor but I have about 70 pcs of 2sa1038s pink marked-I suppose for lowest noise , beta= 520-all of them and I need advice for building a folded cascode with massive paralleled transistors on input and a d3a tube on the output.
Is there a good reason to make the input stage an emiter follower or even a two cascaded emitter followers as tektronix active probes for high frequency if I couple on collector resitance with the tube as in the James D variant?
audio-talk :: View topic - j-FET / Triode Phono front-end
I don't understand if miller effect is as lower as in a normal folded cascode with a npn input and the output on emitter.
If I make a sziklay compound transistor with multiple 2sa1038 and some mje340 so that I could couple on emitter and have huge gm too is that ok in terms of miller effect or phase recovery?
Instead of using 2sa1038 at lower currents I could use mje350 which I have a bunch as manufactured by ASI gold plated pins which I understood that stand pretty good on noie specs.
If inverting topology and using something like hiraga input on emitter and loading the cascode on collector will be better for mc lo cartridges?I read almost the entire topic and I couldn't found a true solid position.
I don't have another good option for lowest noise but these pnp transitors I own and I would like to find a good use for them .I made a 14 tubes preamp for phono and for mc cartridges tubes are not enough.I can't get the money for expensive input transformers so I want to walk solid state only for mc.For mm I will use the tube entry in pentode conection which is fine enough.
I don't have enough knoledges about transistor but I have about 70 pcs of 2sa1038s pink marked-I suppose for lowest noise , beta= 520-all of them and I need advice for building a folded cascode with massive paralleled transistors on input and a d3a tube on the output.
Is there a good reason to make the input stage an emiter follower or even a two cascaded emitter followers as tektronix active probes for high frequency if I couple on collector resitance with the tube as in the James D variant?
audio-talk :: View topic - j-FET / Triode Phono front-end
I don't understand if miller effect is as lower as in a normal folded cascode with a npn input and the output on emitter.
If I make a sziklay compound transistor with multiple 2sa1038 and some mje340 so that I could couple on emitter and have huge gm too is that ok in terms of miller effect or phase recovery?
Instead of using 2sa1038 at lower currents I could use mje350 which I have a bunch as manufactured by ASI gold plated pins which I understood that stand pretty good on noie specs.
If inverting topology and using something like hiraga input on emitter and loading the cascode on collector will be better for mc lo cartridges?I read almost the entire topic and I couldn't found a true solid position.
I don't have another good option for lowest noise but these pnp transitors I own and I would like to find a good use for them .I made a 14 tubes preamp for phono and for mc cartridges tubes are not enough.I can't get the money for expensive input transformers so I want to walk solid state only for mc.For mm I will use the tube entry in pentode conection which is fine enough.
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Try to ltspice your design?
Another MC option, Why not try using Doug Self's MC phono stage. It uses LN PNP bjt's such as Hitachi 2SA1038-84-85. They used it again in the the Elektor 2012 pre-amp. It is a simple ckt to make.
Preamp 2012 (110650-2) - ELEKTOR.com | Electronics: Microcontrollers Embedded Audio Digital Analogue Test Measurement
I have my eye on making a modified HPS 5.1 as Andrew has started doing in simulation.
http://hifisonix.com/wordpress/wp-content/uploads/2010/10/RIAA-Equalization-Amplifiers-Part-One1.pdf
Another MC option, Why not try using Doug Self's MC phono stage. It uses LN PNP bjt's such as Hitachi 2SA1038-84-85. They used it again in the the Elektor 2012 pre-amp. It is a simple ckt to make.
Preamp 2012 (110650-2) - ELEKTOR.com | Electronics: Microcontrollers Embedded Audio Digital Analogue Test Measurement
I have my eye on making a modified HPS 5.1 as Andrew has started doing in simulation.
http://hifisonix.com/wordpress/wp-content/uploads/2010/10/RIAA-Equalization-Amplifiers-Part-One1.pdf
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