SX-Amp and NX-Amp

[Bonsai]

Yes, I will post a circuit up tomorrow.

 

[thimios]

Yes, I will post a circuit up tomorrow.

Thanks ,waiting for this.

 

[thimios]

just before......fire!

Poor man's sx-amplifier,or sx-ampl.with what i have😱
i will never use lead free solder again🙁
BTW it's on my plan testing this with one pair out biased in class A

 

[pinnocchio]

Nice job thimios! Hope you like the sound of it

Ciao!
Do

 

[thimios]

Nice job thimios! Hope you like the sound of it

Ciao!
Do

Thanks pinnocchio.
Here is the completed channel.

 

[Bonsai]

Very nice! I like the Sankens! They will work fine in this circuit.

 

[thimios]

Very nice! I like the Sankens! They will work fine in this circuit.

Thanks Bonsai ,i believe a small modification at the bias circuit is necessary .
It can't go down from 660mV from one emitter to other emitter(output transistors).
PS just now i see that the recommended current is 1.5A

 

[Bonsai]

Yes, I will post a circuit up tomorrow.

I will post it up later this week. Too busy at the moment!

 

[thimios]

I will post it up later this week. Too busy at the moment!

Ok,never mind.
We can wait🙂

 

[thimios]

sx

Today is a listening test day.
Power supply: +/-20V D.C
33000UF/Rail
EI transformer
Biased at 1.5A
One pair OUT.
Offset=0 mV absolutely stable.
From this first test it is clear,this is a very good sounding amplifier,deep bass,clear high .
Congratulations Bonsai good job!
PS measurement test some days later.
Thimios.

 

[Bonsai]

That's great thimios - glad you like the sound - that's the most important thing!

 

[wahyu hening yukie]

my first move. the poor boy sx boards

 

[thimios]

my first move. the poor boy sx boards

Good luck!🙂

 

[thimios]

sx in test bed

Here are some photos from first listening test.

 

[wahyu hening yukie]

thank thimios.but my parts its not new at all. it replace on my ex project. hard to find on local store ksc3053 pair tr.so i use c4793/ a1837 for vas tr has cob about 20 pf.

 

[wahyu hening yukie]

Here is the single sided sx-Amp (15 Watt Class A CFA) PCB layout in Gerber format I promised a few days ago.

I have not built this version (only the THP version)

So, please feel free to take a look.

The circuit is the same as for the one in the write-up on my website except that I have replaced C2 with a through hole electrolytic device and J2 is removed. Further, all the semiconductors are now through hole.

The overlay and circuit diagram are attached as .jpg

NOTE: THIS LAYOUT INCORPORATES THE UPDATED RESISTOR VALUES FOR R28, R29 AND R36 AND R37.


I don't know how to turn this into a .pdf file - anyone got any ideas? This will mean people can etch their own boards.


The write on this amplifier is on my website - here is a link for your convenience: Ovation sx-Amplifier: A 15 W class A Amplifier

Happy building!

hi mr bonsai. i get confuse about cap 2 10uf around tr 3.bc547. its different on single side and double layer schematic. why? regards

 

[wahyu hening yukie]

my sx amp in progres. still confused about 10uf on tr3 ce

 

[Bonsai]

That's C2 - it simply decouples Q3 collector to emitter so that at HF its still a low impedance.

Q3 is the bias generator.

Note the sx-Amplifier bias generator doe not work like an ordinary Vbe multiplier - its actually measuring the voltage across the out devices emitter degen resistors and then controlling the base voltage across the output devices.

😎

 

[wahyu hening yukie]

thanks mr bonsai for fast reply. so which schematic i must to built? , because on double layer schematic C2 its gone.thanks

 

[Bonsai]

Hmmm. How dis I miss that.

Please fit it per the single sided layout.

My DSTHP has the cap fitted. Il have to check the Gerbers - might be the circuit diagram that is missing it.