Aleph 2 Help

[hifileslie]

I purchased my Aleph 2 monoblocs based on KK PCBs as kits about 10 years ago. I immediately built one , but have only now started on the 2nd. I have just noticed that when I built the first one I did not fit R27 ( 221ohm) which, I think is R15 on the original circuit ( highlighted on attachments). I am almost certain that I did not fit R27 based on the advice of the kit seller, but I can not remember the reason given. So some advice please:

What is the function of R27 and what is the impact of not fitting it?
Is it now recommended not to fit it to the KK boards?

 

[Zen Mod]

that transistor is practically overcurrent limiter for lower half of amp , and without said resistor - it's nonfunctional

if you are having some salt between ears , you don't need it

if you're lacking in salt between ears , even that protection isn't enough

 

[hifileslie]

Thank you for replying?
Do you recommend fitting R27?

 

[Zen Mod]

nothing wrong if you put it in place

 

[hifileslie]

If I decide not to have current limiting and do not fit R27 can I leave Q4( current limiting transistor ) and the 150 ohm resistor that forms the voltage divider with R27 still connected on the PCB without any detrimental effect on the amp?

 

[Zen Mod]

yup

that way transistor is closed , same as not present at all

 

[hifileslie]

Thank you

 

[Nelson Pass]

Some people do think that the existence of a transistor protection circuit spoils the cows milk...

 

[hifileslie]

Nelson, Thank you for taking the time to respond. I have decided not to retrofit R27 ( R15 in original circuit ) and leave the over current circuit disabled.

 

[ne5532]

I think it's better to remove this resistance after confirming that the amplifier is stable.

 

[hifileslie]

It is playing music very well without the resistor, but I will test it for a longer period to ensure all is well.

 

[Nelson Pass]

No big deal. Protection in the original circuit is for consumers who are not
able to avoid shorting the output. Fearless DIYers are exempt.