I improved the biasing by replacing a transistor and mounting it to the top of one of the mosfets.
Video:
YouTube - HK Citation 12 modified to use power mosfets
Video:
YouTube - HK Citation 12 modified to use power mosfets
Hi,
You are very fast in building amp! How do you like the sound? Will you try also the complementary version? I didn't start mine yet because I am busy with an another amp.
Regarding the bias of my quasi complementary version, I set it 150 ma when amp is cold and I have around 100 ma when amp is warm. (I used IRFP240).
You are very fast in building amp! How do you like the sound? Will you try also the complementary version? I didn't start mine yet because I am busy with an another amp.
Regarding the bias of my quasi complementary version, I set it 150 ma when amp is cold and I have around 100 ma when amp is warm. (I used IRFP240).
It sounds pretty good.
I just did a power output test, into a 1.95ohm load, it pushes 15-16V at clipping which is around 115-130W.
I used two IRFP450's but will change to laterals when they arrive.
I don't really like P channel fets.
I just did a power output test, into a 1.95ohm load, it pushes 15-16V at clipping which is around 115-130W.
I used two IRFP450's but will change to laterals when they arrive.
I don't really like P channel fets.
ok laterals did not work in this design, with a dummyload it kinda worked but i was only able to get 57W into a 3.9 ohm load, with a speaker it dident work at all, oscillation, huge dc offset and loud humming.
Need to find some other design to be able to use the laterals.
Need to find some other design to be able to use the laterals.
Turns out they do work if the gate resistors are increased to 2.2k, tho i also added some 680pF caps to the gates and source resistors and lowered the bias even further than it was before.
Theres still a hint of a very high frequency left though but its down in the millivolts range.
Theres still a hint of a very high frequency left though but its down in the millivolts range.
Im thinking of trying out complementary mosfets in my citation 12 clone.
Is the 2SK1058 and 2SJ162 any good ? I found a deal with two of each on ebay for 14 bucks + 2 bucks shipping.
Is the 2SK1058 and 2SJ162 any good ? I found a deal with two of each on ebay for 14 bucks + 2 bucks shipping.
Hi Tekko,
Today I tested comp. version (240 & 9240 Irfp) in SPICE, THD was low- looks good. How is reality with turn-on thump>? Mr.Pass spoke about it in his article.
Today I tested comp. version (240 & 9240 Irfp) in SPICE, THD was low- looks good. How is reality with turn-on thump>? Mr.Pass spoke about it in his article.
I have a design similar to the Pass Citation 12, but more like the IR application note - take ilimzn's advice and use IRF240/IRF9140 as complementary pair.
They sound pretty good !!! Even the wife noticed the difference.
They sound pretty good !!! Even the wife noticed the difference.
Due to the lack of interest in this thread i've been thinking that maybe it doesent belong in the pass section anymore since its no longer a harman kardon/pass design after my changes.
Perhaps this thread would fit better in the solid state section ?
What do you think ?
Anyways i upgraded the amp by adding a second pair of output fets, output power only increased by approx 10 watts though.
Perhaps this thread would fit better in the solid state section ?
What do you think ?
Anyways i upgraded the amp by adding a second pair of output fets, output power only increased by approx 10 watts though.
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