30 volt running with a snaps
- Thread starter daVros
- Start date
martin clark
pinko bodger
It's straightforward with only a little bit of maths. The classic equation for LM317 output voltage is:
Vout = 1.25v*(1 + R2/R1) +Iadj*(R2)
- where, in Naim's implementation R1 = 220R and R2 = (3k3 + 680) since the two are connected in series. So, ignoring the Iadj value since the current down the adj. pin is fairly small, you need to alter the values to get the multiplier (1+R2/R1) up to about 24.
The easiest way would be to put a new resistor in parallel with the 220R resistor to drag its composite value down to 170ohm. This means about 790ohm, or use the nearest, larger preferred value (810R). Better still, fit a 1K multi-turn trim pot connected as a variable resistor across the 220R and you will be able to trim the output as fine as you like. Just start with the pot set for max. resistance and wind it down from there, metering the output voltage as it increases.
Vout = 1.25v*(1 + R2/R1) +Iadj*(R2)
- where, in Naim's implementation R1 = 220R and R2 = (3k3 + 680) since the two are connected in series. So, ignoring the Iadj value since the current down the adj. pin is fairly small, you need to alter the values to get the multiplier (1+R2/R1) up to about 24.
The easiest way would be to put a new resistor in parallel with the 220R resistor to drag its composite value down to 170ohm. This means about 790ohm, or use the nearest, larger preferred value (810R). Better still, fit a 1K multi-turn trim pot connected as a variable resistor across the 220R and you will be able to trim the output as fine as you like. Just start with the pot set for max. resistance and wind it down from there, metering the output voltage as it increases.
martin clark
pinko bodger
Glad it worked; so, what do you hear, if anything...?
Martin
I'm getting more of everything, really. Bass has more punch, imaging is noticeably stronger and the treble is more detailed .
Obviously, I'll have to wait a while for it to settle properly, but I was grinning
from ear to ear yesterday within half an hour of powering it all up again.
I can't wait to crank it up properly this afternoon!
I'm getting more of everything, really. Bass has more punch, imaging is noticeably stronger and the treble is more detailed .
Obviously, I'll have to wait a while for it to settle properly, but I was grinning
from ear to ear yesterday within half an hour of powering it all up again.I can't wait to crank it up properly this afternoon!