Hi guys
I need some help, why source resistors on the MOSFETs fukushima 0,47ohm are gone in my F5C after 2 months in one chanel?
I am running the amp at 32VDC. all other parts are ok. Any idea, do I need to increase power of source resistors or their value?
I need some help, why source resistors on the MOSFETs fukushima 0,47ohm are gone in my F5C after 2 months in one chanel?
I am running the amp at 32VDC. all other parts are ok. Any idea, do I need to increase power of source resistors or their value?
One BOM specifies 3W wire wound non-inductive if you are using the "TO220" resistor the may need a heatsink to handle the heat if high biased... do you have a voltage drop across the resistor?
regards, Elwood
regards, Elwood
I wouldn't use eBay resistors on an F5. Get something proper. Caddock, Mills and even Ohmite are better bets. In very desperate situation you could use two or three metal film resistors in parallel.
The MPC74 were from ebay, I will never buy resistors from e-bay.
can i use Dale .5R 3W CP-3 that i have on stock or should i buy 598-SLPX223M050H9P3 from mouser.
I saw in more occasion that people use two 1R 5W resistor for this job, should I also go this way? My amp is biased at 2A (1A per mosfet) per rail at 32VDC, I must to decrease a litle because off the heat 1,6A per rail will be ok. http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1427.html#post3980432
1A of bias through each 0r47 Source Resistor is equivalent to 0.47W. That is only 9.4% of rating.
A 5W 0r47 resistor has a current rating of 3.26A. 2pair output stage allows for a continuous total output rating of 6.52A, (9.2Apk)
These resistors will tolerate an overload of +50% to +100% in the short term.
I would expect 5W Source Resistors to easily manage music and audio reproduction at normal listening levels.
I have been impressed with the quality of Ohmite parts using them for restoration work.
In the meantime, these resistors are important to the resulting sound in the F5, no matter what any empiricist says.
Based on the findings of Simon7000 and others, it's better to use a) paralleled resistors, or B) high quality resistors and in both cases over-rate the wattage considerably. In this case, especially if the amp will run into class B at any point, or get clipped. Simon7000 did a rigorous test for distortion in resistors, fyi.
Imo, 5 watts is nice - there are Caddock and Vishay parts that are rated much higher (with heatsinks) that have been reported as best by some F5 builders.
_-_-
Based on the findings of Simon7000 and others, it's better to use a) paralleled resistors, or B) high quality resistors and in both cases over-rate the wattage considerably. In this case, especially if the amp will run into class B at any point, or get clipped. Simon7000 did a rigorous test for distortion in resistors, fyi.
Imo, 5 watts is nice - there are Caddock and Vishay parts that are rated much higher (with heatsinks) that have been reported as best by some F5 builders.
_-_-
hi guys! please i need to chose betwen
Mills mra05
or
Vishay / Dale RW74UR470FB12 (Mil Type)
or
Panasonic ERX-3SJR47
i think i will bias at 1.5A to canal (0.705V on resistor source)
please is there anyone there who has had the opportunity to experiment with sonic effects on the different resistors?
Thanks
Antonio
Mills mra05
or
Vishay / Dale RW74UR470FB12 (Mil Type)
or
Panasonic ERX-3SJR47
i think i will bias at 1.5A to canal (0.705V on resistor source)
please is there anyone there who has had the opportunity to experiment with sonic effects on the different resistors?
Thanks
Antonio
Use the ones you want to use in the project. They are all functionally and objectively identical.
If I had to choose, I'd select those that were the nicest color with the PCB...
If I had to choose, I'd select those that were the nicest color with the PCB...