SC200 AMPLFIER LOW VOLTAGE SUPPLY 25-0-25 V AC AND COMPONENT CHANGES

Hi I am currently building the SC200 power amplifier. A lower AC voltage of 30-0-30 transformer can be used by reducing Q7 collector resistor to 15kohms and reduce the 2 collector resistor of Q6 to 4.7koms as detailed in the magazine. I have a slightly lower voltage transformer 25-0-25 V AC. Will the component changes work with my lower voltage transformer or will I need to reduce the resistances further and change any others??.
Can anyone help.

Thanks
Heath

Appreciated. Fully knowledgeable. Great Job!

Hi Rajiv Kumar with reference to my SC200 post above I am not sure what you are referring to with your comment above.I am asking if the resistance component changes to the SC200 amplifier will work on lower power supply voltage of 20-0-25 V AC.
RegardsHeath 

Hi Rajiv Kumar with reference to my SC200 post above I am not sure what you are referring to with your comment above.I am asking if the resistance component changes to the SC200 amplifier will work on lower power supply voltage of 20-0-25 V AC.
RegardsHeath

It appears to be a spam post unfortunately, I'll get it looked at. Unfortunately, much as we would like to,  EPE itself cannot guarantee help with component or design modifications, because we could never investigate or guarantee the outcome.Alan W

Ok why not provide an email for the developers so that subscribers who are building this project can get support and get there technical questions About the project  answered.
Regards
Heath

Hi Heath,

An Email address is provided in the magazine Editorial page where technical
queries may be sent. Also please see EPE Contact details.

I'm sure you will understand that providing unlimited 1:1 technical
support for something complex like the SC200 amplifier isn’t trivial or even viable,
due to the expectations of receiving timely personal attention to all kinds of highly
technical questions worlwide.Your post asks whether your power supply modifications will work: we
would never say ‘they might in theory’ because the magazine ends up ‘owning’
the problem of redesigning a circuit. Since we haven't built or tested the mods
ourselves, we couldn’t guarantee the results, and construction is beyond our
control anyway, but doubtless we would be held responsible if any problems arose
subsequently.
It’s for these reasons that we state we cannot help with custom
modifications, but other constructors may offer some advice or ideas in the
forum. We will always try to help where we can, but I'm hoping some other
readers might chip in with their own suggestions as well.Meantime I will forward your enquiry to SC to see if I can get an answer.
Alan W / EPE

Hi Alan thanks for your reply. I do understand providing unlimted technical support is not practical and i am not  asking you provide unlimited technical support. The question I asked directly related to the resistance changes specified in the article and as a result the voltage supply range the amplifier would work sucessfully given these resistance changes. My question is a fairly basic one i think. Minimum and max supply voltage range with and without the circuit resistance specified in the article would be very usefull for people building this amplifier to know.
RegardsHeath

This just arrived from the designer which I hope is of help.I suggest scaling the components to suit the lower supply voltages to avoid
problems.
I expect DC supply rails of around +/-35V from a 25-0-25 transformer. So the
22k resistor should be reduced to 13k and the 6.8k resistors to 3.9k.
Nicholas Vinen
Editor
SILICON CHIP MAGAZINE