WESTRAK AMP NA 500 WATTS @ 8 OHMS LOAD

[tony]

not required yung 1.5k, a  VAS current of say 5mA will cause a drop of 7.5 volts, sunog ang output trannies mo kung nagkataon.....

hindi well defined yung VAS mo since you have 2 x 5k trimmers as load of the input LTP.....i suggest make one fixed if you want to adjust the output offset from there.....

these resistors should have been fixed and metal film types....offset adjustment can be done in many ways......ginawa ko rin yan sa tigersaurus, pero sa tutoo lang "tirang daya" yan.....

using the 2SC5200 with its high beta and low beta droop at high current, i am wondering why you use triple darlington at all....

Ah, sure bang may 1.5K dun sa emitter ng bias Servo? Kung meron man di ba mataas yung 1.5K?
Tanong lang bro, di kasi ako mapalagay dun.
 

[tony]

jbmobile, have you tried to measure your rails at full blast? gaano ang iginabagsak ng voltahe? from 99 to 75 volts ba?

kasi to calculate power, the rail voltage at full power must be taken into account, not the idle rails......

[jbmobile]

@sir tony we've measured  +/-61vdc  rail drop at full power @8ohm load ...will update about the biasing scheme later..thanks for pointing out the weakness of the diff stage..only an adaptation of the westrack design,haven't done fixing the load resistors..will wait for another valuable inputs from the masters out there..again many thanks sir tony..

[jiggins20]

taas naman ng pgbagsak.....hindi ba maganda gamitin sir tony ang triple darlington output...

[tony]

taas naman ng pgbagsak.....hindi ba maganda gamitin sir tony ang triple darlington output...

yung Pioneer Spec2, from 91 volts to 72 volts, full power....

at 61 volts, then most likely power developed is about 150 watts....this tells you how the power transformer can be made bigger.......

triple darlington is good if your VAS runs about 5mA current, pero kung mataas naman ang Hfe ng driver at output then pwedeng simpleng darlington lang, more so if you run your VAS at say 10mA or more......

[jbmobile]

sorry po +/-81VDC voltage drop..nagkamali type kanina.measurement was taken on site sa gig. .saka sa latest update ay ginawang 10k values ng 5.6k resistors at sa trimmers na din..VAS resistor ay ibinalik sa 390 ung 200 ohm,pati na din 100ohm/2W to 1k,2W.ganun din sa biasing cuircit,maliban sa 1k trimmer...

[jbmobile]

tama kau sir tony..our first attemp to uprate with trimmers at the diff stage proved to be finicky to adjust..and before i forgot,,1k5 resistor at the emmiter of the biasing tranny is not supposed to be there.. sorry mga sis,my mistake again..

[tony]

sorry po +/-81VDC voltage drop..nagkamali type kanina.measurement was taken on site sa gig. .saka sa latest update ay ginawang 10k values ng 5.6k resistors at sa trimmers na din..VAS resistor ay ibinalik sa 390 ung 200 ohm,pati na din 100ohm/2W to 1k,2W.ganun din sa biasing cuircit,maliban sa 1k trimmer...

sounds more reasonable, power is about 300watts at 8ohms.....a big drop in rail voltage means that your power traffo will heat up more than if the drop was smaller...

[jiggins20]

sir tony paano po imeasure current ng vas?

[Disabled]

gawin na tong sticky

[tony]

sir tony paano po imeasure current ng vas?

good question, i was hoping somebody would ask.....+1 for you..

to measure the VAS current, measure the voltage drop across the resistor at its emitter or any part of its circuit in series with the VAS....it then becomes a simple ohms law computation....

[tony]

gawin na tong sticky

calling Ate Shey, please make this thread sticky....

[Disabled]

UP!


How about mag mods tayo for home use?
parang audiophile approach kung baga

[Disabled]

eekk nag momods na ako ngayon sa input stage
kaunting galaw lang eh may lalabas na 100mv

[Disabled]

help,paano po ba sukatin ung bias at ilan po dapat???

[danny]

may na ipost na si sir tony ng about biasing
nde ko lang matandaan kung dito sa thread na ito
are you talking about the idling current?
you can get that across the emitter resisitor
measure the voltage there and do the math
our simple ohms law 

[Disabled]

di pala pde paghalu haluin ng ibat ibang transistors ung sa triple darlington stage
gumagalaw kaagad ung DC out kapag mismatch..

[tony]

help,paano po ba sukatin ung bias at ilan po dapat???

post mo yung schematic para meron tayong point of refference sa discussion.....

[jiggins20]

subs....

[Disabled]

post mo yung schematic para meron tayong point of refference sa discussion.....

ung sa page 26 po..