Amp Camp Amp - ACA

[TonyTecson]

2sk170 works fine on 24 volts.....

 

[umut1001]

That’s a good idea. I do have removable inut caps on mine so as to insert a smaller cap to create a “PLLXO”. Much higher quality part as well.

dave

Yes i just wondered if i can use bipolar or film capacitors instead of output and input electrolytic polar capacitors(i remember somebody tells film caps can not be used for dc blocking)

 

[Stanislav]

All capacitors block DC as long as they are in series with the signal.
And have the appropriate voltage rating.
Cap value determines how high above 0 Hz they start conducting AC.

Worth reading some basic electronics theory.

 

[planet10]

... film capacitors instead of output and input electrolytic polar capacitors...

Elcos are usually used because of size and cost. Price a 20kµF poly cap.

But they do work better.

We did a small Class A EL84PP amp with no elcos, it made a significant improvement. PS caps in a tube amp do not need to be as large (but higher voltage).

dave

 

[umut1001]

I have ero 4.7uf 40v mkt1826 capacitors so i can use 2 of them in the input by soldering one on and other under pcb and can use instead of 10uF input caps. I do not remember where i saw it that someone said only polar caps should be used on some circuits

 

[TonyTecson]

in my 48v ACA i used 2.2ufd input cap, bass is so fabulous i promise....

 

[umut1001]

Wow 48v Aca ! Schematic same ? Thanks

 

[ranshdow]

Hi, I'm sure this question has been asked and answered in some form already, so apologies. Also I have zero formal electronics training, so hopefully the forum will humor me. :

The standard wiring diagram for an ACA v1.8 has speaker + out (red) connected to ps ground. Does this mean that the output of the ACA as wired reverses the polarity, thus inverting (correcting) the phase back to non-inverted when speaker + out (red) is connected to the red terminals of the speakers?

 

[Mooly]

Yes, the ACA is inverting of overall phase and so the reversed speaker plug colours are purely to give overall non inversion of phase when it is connected conventionally i.e by a user who goes off the colours as indicating correct polarity.

 

[ranshdow]

Awesome. Thank you Mooly!

 

[Mooly]

You're welcome

 

[TonyTecson]

Wow 48v Aca ! Schematic same ? Thanks

basically the same, but addressed the 40v limitation of the 2sk170...

 

[TonyTecson]

the 2sk117 has a 50 volt rating, so can be used, will try that sometime too...

 

[indra1]

Jfets will have higher gate leakage at higher Vds, best to avoid whenever possible.

 

[TonyTecson]

ok, i am already scared off....

 

[TonyTecson]

i have a previous build running on 24vdc and will move to 36vdc supplies, i will just replace the jefts to 2sk117.....

 

[Zen Mod]

covered early in the thread .....

 

[TonyTecson]

sorry, too lazy to read from the start....

 

[umut1001]

i have a previous build running on 24vdc and will move to 36vdc supplies, i will just replace the jefts to 2sk117.....

I have 2sk209gr in stock so i can parallel and build them with 48v

 

[Zen Mod]

why?

simple RC or R-zener-C isn't elegant enough, to keep original JFet?