lm3886 one channel is born

[ampimp]

Hi
Well the first channel of my lm3886 is up and running . it is inverting and using 10k on input and 220 feedback resistors composit carbon nothing special. the decoupling caps 0.1 uF are wima as is the 220 pf between the inputs. i have 1800uF 40v rifa peg225 Electrolytics for smoothing Low esr and very large ripple current rating wich are electricaly only approx 40 mm to the chip.Oh i nearly forgot the 10uf on input all i know is it is blue and squareish and of film type. rectifier not seen in piccys is 35 amp 200v the type molded into an aluminium block again genral purpose and the last is the torroid taked from an old nad 320bee i have removed some windings to get my dc to 28 volt per rail as before it was 42.5 off load and that was too risky.
I made the board with a dremmel and a craft nife and layed out the board to make it a easy as possible to do with the tools i have . the psu is wired with the wire taken from the transformer also the speaker connections i twisted the 1.2mm enameld copper wire together then covered in heatshrink sleeving . Here are a few piccys sorry for the quality .oh the sound well that will require another thread three words pop into my head sing dance foot tap feel good that is not just me it seems to effect anyone who listens to it like that . ill be back v soon with completed amp

[AndrewT]

Originally Posted by ampimp

i have removed some windings to get my dc to 28 volt per rail as before it was 42.5 off load and that was too risky.

your range of mains supply voltage is 216Vac to 254Vac.
What is the PSU voltage when mains is at 254Vac?

[ampimp]

Originally Posted by AndrewT

your range of mains supply voltage is 216Vac to 254Vac.
What is the PSU voltage when mains is at 254Vac?

Hi Andrew
I have measured the mains supply at different times of the Day and night .
Most of the time it is at 249-250 Vac i have seen it at approx 225 vac.
When the mains is at approx 250 i have 26.5 vdc with amplifier on but not playing.The next project will be a variable regulated supply so i can try out different voltages and listen to there effect on sound. I did read in one of nelsons articals that differences between the +- dc supply rails can lead to finding a sweet spot. another thought around the same would be to have say three preset rail voltages i can choose from to get a different sound.Ie higher voltage harder sound, lower voltage softer sound.
It is just an idea so may not happen . Im still reading and learning and i will be building one of the very popular projects That you mentioned to me Mongrel symasym aksa and the likes.
Thankyou for the guidance so far Andrew you have been a massive help.
Best Regards Ian

[AndrewT]

[QUOTE=ampimp;2347139........... the mains supply ...............
Most of the time it is at 249-250 Vac[/QUOTE]If your supply is as high as that most of the time then your distribution transformer is set to the wrong tapping for your property. Or perhaps, your voltmeter is reading wrong.

Contact your supplier and ask them to come and check your supply voltage and if necessary ask them to monitor the voltage throughout a continuous period of a few days.

[ampimp]

Well that is me and the whole estate. The meter i use is a fluke 75 and it was recently calibrated. I will check with another meter just to be sure i doubt the electricity company will even listen

[ampimp]

Regards Ian