2SK170 Hybride idea IRF610, 100 mA out

[lineup]

Hi

Here is a FET - Bipolar - MOSFET hybride idea.
A powerful and very high performance preamplifier.
Yet very much KEEP IT SIMPLE

3 transistors only = JFET input, BJT VAS, MOSFET output.

This version uses 2SK170 input and IRF610 follower stage.

Following my Lineup philosophy of using separate voltage supply for each stage.
Something I have in common with a few other Hifi designers,
like eg. the eminent Mr. John Curl.

Any improvements suggestions and questions are welcome.
The simulated distortion shows nice falling harmonics at or below the -100dB level.
Worst sim test so far: 10 Vrms (+-14.1422 Volt peak ) into 2 kohm.
Neither does the distortion at 7 Vrms ( 10 Vpeak ) into 500 ohm show no problems.

Upper - 3 dB bandwidth is trimmed to 1 MHz ( 1000 kHz ).
Close to same frequency shows for -45 degrees phase.

Lineup
-------------------------------------

I assume that those want to try this amplifier knows
- how to make good CCS sources ( search forum )
- how to make 3 good voltage supplies, one for each stage ( search forum )

[jjanderson]

Thats an super idea! you can feel that when you look at the responses of your post
I dont understand why you want to use the 2sk170 thist transistor isnt cheap and isnt easy to get, i think also that different power supplies for each stage isnt practical and dont give you a better result.
When you belive that, you belive in silver cables for 1000$ and CD ionisators for 300$ too.
There are alot good opamps like the NE5532... this opamp sounds better then 99% of the selfmade preamps.
Have fun!

[nelsonvandal]

I can't understand how anyone can regard NE5532 as good sounding. It sounds decent, not more than that. It has a kind of "harmless" but dull sound. Even the boring OPA2132 sounds more exciting. I'd be surprised if any monolithic opamp could give a circuit such as this a match.

BTW, in Sweden a 2SK170 is about 1 USD. Expensive?

[tschrama]

Originally posted by lineup
Hi

Here is a FET - Bipolar - MOSFET hybride idea.
A powerful and very high performance preamplifier.
Yet very much KEEP IT SIMPLE

3 transistors only = JFET input, BJT VAS, MOSFET output.

This version uses 2SK170 input and IRF610 follower stage.

Following my Lineup philosophy of using separate voltage supply for each stage.
Something I have in common with a few other Hifi designers,
like eg. the eminent Mr. John Curl.

Any improvements suggestions and questions are welcome.
The simulated distortion shows nice falling harmonics at or below the -100dB level.
Worst sim test so far: 10 Vrms (+-14.1422 Volt peak ) into 2 kohm.
Neither does the distortion at 7 Vrms ( 10 Vpeak ) into 500 ohm show no problems.

Upper - 3 dB bandwidth is trimmed to 1 MHz ( 1000 kHz ).
Close to same frequency shows for -45 degrees phase.

Lineup
-------------------------------------

I assume that those want to try this amplifier knows
- how to make good CCS sources ( search forum )
- how to make 3 good voltage supplies, one for each stage ( search forum )

Nice ... looks like the Threshold NS-10 has married a low noise SK170 and a Psslabs IRF610.. should work excelent if you ask me...... and would be a nice headphone amplifier too!

[Mooly]

Hello Lineup,
Your circuit has that "it looks right" feel to it You know- that inexplicable thing. I am sure it would sound great too !!!

[jjanderson]

Yes i am shure too, i often **** on my amp that even sonds much better

[h_a]

Hi Lineup!

Nice to see you posting nice little amps here!

However I do have a few questions: different rails are used to be able to run the outputs close to the rail, but your third rail of 41.5V seems to be useless here as it only drives a voltage divider?

The 50V for the frontend are also far higher than needed to run the output to the rail - but no harm. By the way did you check power dissipation for the K170? Seems only a GR could fit here.

As component values are missing I cannot say for sure, but it seems that you may get rid of the input coupling cap (if you want that is).

Of course you can also plug an Aleph Current source into it and get rid of the output cap as well ;-)

All the best and happy building, Hannes