Leben CS300x feedback loop cap

[Glass_painter]

cs300x

Hello All,

I still can not figure it out...

I know that without the additional bass networks in the FB loop the 100 uf is not needed. how come adding one more network in series requires this cap?

What am I missing here?

Thanks.

Glass_painter

 

[DF96]

Switching clicks. You always need to keep DC away from signal switches which might be used with the equipment switched on.

 

[Glass_painter]

if I understand correctly, if I choose one setting (+5db for instance) and wire it permanently (omit the selector switch) I can short the 100Uf cap.

Is that the case?

Thanks,

Glass_painter

 

[DF96]

Yes, apart from a small bias shift in the first stage (which is unlikely to do any harm).

 

[Glass_painter]

Great, thanks for the information.

What damage do you think will happened if you click the very small dc voltage in the FB circuit with the selector and the cap shorted?

 

[costis_n]

A very big click on your loudspeakers, because You will be disconnecting - reconnecting the feedback of the amplifier. I do not know if it will kill your woofers or your tweeters. I think the woofers, but i am not sure.

 

[Glass_painter]

Great, thank you all.

 

[Glass_painter]

cs300x

Hello All,

I would like to build this amp utilizing ecl86 instead of the the 12ax7 and el84 the design calls for originally. Based on all I was find on the net should be no problem although the power will be lower then the original.

What do you think?

In addition, I am considering removing the NF electrolytic cap and re arraigning the bass boost filters in such a way that it will always be in the loop and the selector will decide which network is shorted - thus taken out of the loop WITHOUT disconnecting the loop.

This way, the NF loop is never cut off and reconnected only the resistance and capacitance in the loop changes with the selector.

What do you think?

Thanks,

Glass_painter

 

[Glass_painter]

Bump, anyone?

 

[costis_n]

If you draw the switching circuit it will be clearer.

 

[Glass_painter]

Leben cs300x

I will try

 

[Glass_painter]

Look at the FB network, This is what I was referring to.

 

[costis_n]

Moving the switch while the amp is operating, will short the 15K resistor, making a DC "step" thump. Not as bad as previously maybe, and depends on your speakers if you kill something or not.

Good idea aboutthe ECL86, it should work (with reduced voltage)

 

[Glass_painter]

Great, thanks for the info.