Integrated No NFB Son of Follower

[VladimirK]

Here is almost completed integrated amp, which unifies No NFB headphone amp/preamp with the Modified Follower. As expected, sounds exellently.
Output "cap" is a ring-like cluster of 1000uF low-ESR caps (SamWha WL) with 100uF polypropylene shunt (Solen).
Current was decreased to 2A, since with 60V power rail power dissipation goes to high for a single transistor.

[Bigun]

Looks very nice Vldimirk.

I suspect you must own a heatsink company

[VladimirK]

Originally Posted by Bigun

Looks very nice Vldimirk.

I suspect you must own a heatsink company

Some years ago I was inspired by Nelson Pass for building Zen4 and Zen9, then I wanted more and more power from them, and this has ended up by ordering of 6 big custom made (machined) heatsinks. Since that time, only Zen9 (4,8A current, disconnected CS modulation) is living still, another two pairs of heatsinks have travelled to follower-based designs.

[VladimirK]

Now the Son of Follower is being breaking in. Pass's style has touched a bit this creation.
I would also like to mention, that VT9 and VT10 can be easily replaced by more obtanible MOSFETs, since output impedance of the driver stage is nearly 2 Ohms (it is possibly a record value). I used to connect the driver stage directly to loudspeakers, and sound was quite listenable.

[Bigun]

Originally Posted by VladimirK

Pass's style has touched a bit this creation.

Indeed, I noticed also the front panel design

[miklos]

A possible PCB for the power amp.
The board is not include the large capacitors and two resistors: C6,7, 11, and 12, the resistors R20, 23 and R1 the potentiometer.
The size is 17.8x4.5 cm (7x1.8 inch).

[VladimirK]

Since getting HF transistors is not an easy task, I would propose using K1530 as VT9, VT10. At this, R15 and C4 could be decreased for preserving the passband of the amp.
Also, now I can state that the Low-ESR SamWha WL 1000uFx63V, in the cluster arrangement, give very good result for the output cap. Of course, one could test also Nichikon KZ or Elna Silmic II, for instance. With 100uF polypropylene shunt, sound easily competes and outperforms that of a good tube SE amp, at all frequencies.

[daudio25]

And the minimum voltage is? Since 120w disipation kind a on a high side

[Bigun]

Vladimirk,

You know, it's kind of strange to see that you are from a city world famous for the quality of it's vacuum tubes, yet you are a solid state guy ?

[VladimirK]

Originally Posted by Bigun

Vladimirk,
You know, it's kind of strange to see that you are from a city world famous for the quality of it's vacuum tubes, yet you are a solid state guy ?

My amp building activity is not aimed against tubes, simply I believe that HF transistors and tube-like simple SS schematics could do the job even better (sound-wise). But, for achieving this, one should observe few design principles. One of them - make the regions with alternating currents as compact as possible, for precluding parasitic interactions, induced noices and post-effects. Shunt PS and follower-like solutions are very good for this.
Many "perfect" schematics with very low THD do not sound good, since the sound is sensitive to many usually unaccounted things.