TSSA - The Simplest Symmetrical Amplifier

[Lazy Cat]

🙂

 

[JZatopa]

Have you built it? How does it sound?

 

[Bigun]

F5 😀

 

[Lazy Cat]

FA 😀

P.S. F5 with input BJT-s. 😉

 

[Lazy Cat]

Have you built it? How does it sound?

As I was informed Mr. Nelson Pass built it. Everything what comes from him sounds perfect.

 

[AKSA]

Andrej,

I really like your simplification of the SSA. Very elegant.

Hugh

 

[sonnya]

Place those diodes on top of the mosfets (top diode on bottom mosfet and bottom diode ...).

 

[Lazy Cat]

Hi Aksa 😉

Thanks, the credit goes to NP F5. Still it is also very close to basic SSA, somehow logical step to a really low parts count, still maintaining input BJT-s and to have bias/offset setting. I couldn't resist to draw it ... 🙂

Regards, Andrej

 

[Lazy Cat]

Place those diodes on top of the mosfets (top diode on bottom mosfet and bottom diode ...).

You mean thermally? 🙄

Electrically diodes provide bias conditions for input BJT-s and thus for the whole amp. Output bias should be class-A. 😉

 

[buzzforb]

Might have to try this one. See how the bjt compares to jfet.

 

[sonnya]

I Will build it tomorrow and run it on an analyzer

 

[Lazy Cat]

Sonnya you're the Man!

 

[AndrewT]

I thought Sonnya is/was female.

 

[juma]

...P.S. F5 with input BJT-s. 😉

I entertained that idea and I liked it, but I did it in a different manner... 😀
Off course, using Laterals exclude the need for thermal compensation.

1. Basic idea (post #8231):
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-165.html#post2227201

2. Working amp (post #6):
Radjanje F5 clone - diyaudio.rs

 

[sonnya]

Male - i cannot multitaske

 

[sonnya]

For some reason, the last time we cleaned out in the old component stock we have thrown out all TO-92 bjt!!!!

So i am building it today with KSC3503 and KSA1381. I think the would be a good substitute besides from the gain. But driven from a Low z source it should not be an issue

 

[Lazy Cat]

For some reason, the last time we cleaned out in the old component stock we have thrown out all TO-92 bjt!!!!

 

[Lazy Cat]

Male - i cannot multitaske

natural talent 😉

 

[sonnya]

Schematic explains itself. 😉

1K trimmer is replaced by a 2k2 fixed and in the negative part 1k + 2k trimmer.

RC top and bottom is set to 2.2k=> more OLG.

BC550 and 560 is replaced by KSC3503 and KSA1381.

at 24V it will settle to about 1.2 - 1.4 amp.

for an equal current in the mosfet an vgs difference on the 10n20 and 10p20 from exicon of about ~1V. This will lead to and offset. Maybe a diode in series with one of the collector resistors will help a lot!?.

I have attached the measurements.

 

[sonnya]

The amp.