Hi anybody, A couple of questions to whomever might know....
1. Fetzilla 1.4uH inductor with 10R 1 watt paralled internal resistor, does it make a difference if I put the resistor under instead of inside the inductor?
2. On the pcb board in the position of the three trippots is a small printed star, hence I assume that the trimpot screw is positioned with the screw side the same side as the star.
3. For initial positioning, I assume I set both trimpots to middle position, hence 250r for both p1 and p3 and 1 k for p2.
4. With my build speed probably will not need to know this for some time, but has anybody written instructions on how to set bias and adjust offset. on which resistors would I take measurements for these and what values?
Apologize for beginning questions but this is learning curve hobby for me. Looking forward to getting this Fetzilla up and running. still stuffing the boards but have resistors and diodes in place now....
Cheers, John
1. Fetzilla 1.4uH inductor with 10R 1 watt paralled internal resistor, does it make a difference if I put the resistor under instead of inside the inductor?
2. On the pcb board in the position of the three trippots is a small printed star, hence I assume that the trimpot screw is positioned with the screw side the same side as the star.
3. For initial positioning, I assume I set both trimpots to middle position, hence 250r for both p1 and p3 and 1 k for p2.
4. With my build speed probably will not need to know this for some time, but has anybody written instructions on how to set bias and adjust offset. on which resistors would I take measurements for these and what values?
Apologize for beginning questions but this is learning curve hobby for me. Looking forward to getting this Fetzilla up and running. still stuffing the boards but have resistors and diodes in place now....
Cheers, John
thanks meanman, that is really good documentation in the first post.
Still does it make a difference if I put the resistor inside the coil and will it work equally as well as if it is underneath. thanks, John
ps. glad things are progressing on the group buy... looking forward.
On this board, now have all resistors pots and diodes soldered! making progress.
Still does it make a difference if I put the resistor inside the coil and will it work equally as well as if it is underneath. thanks, John
ps. glad things are progressing on the group buy... looking forward.
On this board, now have all resistors pots and diodes soldered! making progress.
Some say it will others say it don't.I've put mine inside too.
Made the parcels ready to ship now I've to find the time to go to germany for shipping much cheaper there.
Great, we appreciate all the work on the group buy, the fetzilla from the group buy it will be for a friend of mine. I squeezed the resistor inside last night and seems to fit well so that is done on both channels.
after reading the post, Just to make sure I got this right on adjustments.
Step one: To set Quiceint to 370 MA, I use P1 to measure across 0.1 source resistors and adjust for 40 ma or 37 ma on both resistors. (p18 and p17)
Step two: to set the voltage across the bootstrap resistor R12 to 24-26 volts (P3) I simply measure both sides of the resistor and should get 24 volts.
Step three: Then offset which measure simply between speaker terminals plus and ground and should be plus or minus 10 m. short imput to ground for this.
There was something about "Adjusting r12 to set T3 vds at approximately 8 volts" in the thread which I do not quite understand. it it correct to understand thatn when r12 when it is adjusted in step two ato give 24/26 voltes, this should give about 8 volts to T3 and I measure between the Drain and source of t3. if not, does this mean I may have to change R12 to a different value if I do not get 8 volts to T3?
all is soldered on pcbs except transisitors and am awaiting on diode which supplier did not send in original package to put everything together and adjust.
Many thanks if someone could reconfirm this is the correct way to adjust.
thanks, John
Step one: To set Quiceint to 370 MA, I use P1 to measure across 0.1 source resistors and adjust for 40 ma or 37 ma on both resistors. (p18 and p17)
Step two: to set the voltage across the bootstrap resistor R12 to 24-26 volts (P3) I simply measure both sides of the resistor and should get 24 volts.
Step three: Then offset which measure simply between speaker terminals plus and ground and should be plus or minus 10 m. short imput to ground for this.
There was something about "Adjusting r12 to set T3 vds at approximately 8 volts" in the thread which I do not quite understand. it it correct to understand thatn when r12 when it is adjusted in step two ato give 24/26 voltes, this should give about 8 volts to T3 and I measure between the Drain and source of t3. if not, does this mean I may have to change R12 to a different value if I do not get 8 volts to T3?
all is soldered on pcbs except transisitors and am awaiting on diode which supplier did not send in original package to put everything together and adjust.
Many thanks if someone could reconfirm this is the correct way to adjust.
thanks, John
John,this isn't clear for me too.Didn't check this myself maybe do it someday to know.
John,do you already have FetZilla boards?
John,do you already have FetZilla boards?
THANKS MM. I HAVE THE BOARDS FROM A MEMBER WHOM WANTED TO SELL HIS, I STILL WANT THE ONES FROM THE GROUP BUY THOUGH WHICH YOU DID. JUST MISSING A DIODE TO PUT IN AND HOOK UP TOGETHER.
I THINK YOURS WORKED WITHOUT THE t3 VDS AT 8 VOLTS SO i WILL TRY THE THREE ADJUSTMENTS AS WRITTEN IN THE BUILD GUIDE AND SEE WHAT I GET. BEST, JOHN
I THINK YOURS WORKED WITHOUT THE t3 VDS AT 8 VOLTS SO i WILL TRY THE THREE ADJUSTMENTS AS WRITTEN IN THE BUILD GUIDE AND SEE WHAT I GET. BEST, JOHN
Attention Fetzilla builders.
I have just listed 2 pairs of transformers that are ideal for Fetzilla's. One pair is Avel Y236504 that were used in Aksa's for a long time. And the other pair is Triad 160VA 2x24V that I used in my own Fetzilla, when I had it operating.
http://www.diyaudio.com/forums/swap-meet/237693-fs-avel-y23604-160va-2x25v.html#post3527230
http://www.diyaudio.com/forums/swap...agnetics-160va-2x24v-toroids.html#post3527232
I have just listed 2 pairs of transformers that are ideal for Fetzilla's. One pair is Avel Y236504 that were used in Aksa's for a long time. And the other pair is Triad 160VA 2x24V that I used in my own Fetzilla, when I had it operating.
http://www.diyaudio.com/forums/swap-meet/237693-fs-avel-y23604-160va-2x25v.html#post3527230
http://www.diyaudio.com/forums/swap...agnetics-160va-2x24v-toroids.html#post3527232
Thanks Steve, useful information for trafo buyers in US.......
MM,
Never measured, but I would assume a Zout around 0.3R, giving a DF around 26 with 8R speakers. BTW, this is not very useful for audio amps, it's a curiousity only, although I've found that a high DF means a lot of global feedback which leads to poor decay when playing notes, rather like playing a piano without using the sustain pedal.
Most people don't enjoy music like this; they prefer notes merging with the next, for some reason it gives a more satisfying midrange and bass sound.
I try to get DF less than 40.
Cheers,
Hugh
MM,
Never measured, but I would assume a Zout around 0.3R, giving a DF around 26 with 8R speakers. BTW, this is not very useful for audio amps, it's a curiousity only, although I've found that a high DF means a lot of global feedback which leads to poor decay when playing notes, rather like playing a piano without using the sustain pedal.
Most people don't enjoy music like this; they prefer notes merging with the next, for some reason it gives a more satisfying midrange and bass sound.
I try to get DF less than 40.
Cheers,
Hugh
As I can say for certainty is that the FetZilla has very controled bass.The FetZilla doesn't need high DF.As I'm no electronic engineer I've to believe what other people say but I've my personal experience.If you hear the Fetzilla I would think ,no I don't need high DF.The easiest way to get controled bass is a high DF but it influence sound right?
But when you've a well tought design you can have a rock steady and controled amp with less DF.The fetZilla is prove of this.Just my 2 cents!
But when you've a well tought design you can have a rock steady and controled amp with less DF.The fetZilla is prove of this.Just my 2 cents!
Troubles,put together my brothers fetZilla and the trouble has started.The first 0,1R between the psu caps on the positive side began to smoke.I couln't measure(across R17-18) the other channel it shows nothing on my multimeter not even over R12.