That's why I said "to me...."
I don't understand why you've started this thread. To **** off people in the Pass Labs forum? Clearly you don't intend to spend time to understand if anything is wrong with the amp. You didn't even build it yourself... and then you compare it to a commercial class D amp.
While I personally don't enjoy the sound of Class D, I'm willing to believe that they can sound good if done right. However, I'm not willing to believe that the F4 sounds "bad" in comparison. It may not sound as good to you, but it certainly doesn't sound bad.
Nelson, to be hones I wondered about that too. is it OK if I dropped it and omitted only Q204 and the parts around the Zener from the original schematic? http://www.diyaudio.com/forums/atta...4350155-f4-power-amplifier-pass-ba1-front.jpg
continuing a conversation with you is clearly wasting my time. you seem to be excessively biased, while most of the people realized that this is not meant to **** anyone. if I'm not posting pics or measurements the very next second someone is asking me to might maybe mean that I have more important things to do at the moment?
I think the outputstage is an F4, there seem to be SK170 and J74 on the right side and the source resistors seem to have 0,47 Ohm.
you dropped the correct parts for biasing, it is done by the F4 components....TL431
and the output semiconductors are marked with different colours so they could be complementary.. but mr push pull can look!
at the input of the outputstage is 47k and 1k at the j-fet input (last picture)
or are my eyes bad...?
you dropped the correct parts for biasing, it is done by the F4 components....TL431
and the output semiconductors are marked with different colours so they could be complementary.. but mr push pull can look!
at the input of the outputstage is 47k and 1k at the j-fet input (last picture)
or are my eyes bad...?
Last edited:
Clearly. What irks me is that you start a thread by saying that the F4 is beaten "hands down" by a commercial class D amp without so much as admitting that there may be something wrong with the F4 clone (a poor one at that). I'm not asking for any measurements, but only your admission that there may be something wrong with it.
If it's an F4 OS, then you don't need any of the parts around the zener or
Q204 for that matter.
Mr P-P,
hope you don't mind me saying, but the heatsinks of the amp seem to be assembled with scrap parts.
The L-angles that hold the output devices appear to be attached to the heatsink contraption by a single bolt in the center.
With such a slip-up, there's likely a range of issues with the build.
DIY isn't about expensive cases, more to do with attention to detail.
(checking JFETs for authenticity is very easy, the little ones in particular)
I wrote about the "heatsink" issue myself, but after 3 hours of service the temp of the transistors reaches about 65 deg Celsius. they're attaced using 3 bolts each.
how do you tell fake J109's? that would really help.
Last edited:
well - without gong too much in possible issues ( except already mentioned that every discrete OP , which used BA FE is , needs elaborate PSU reg ) I can say just one thing - my F4 specimen , known as Papa's Koan , is blameless as much one power amp can be blameless ;
if paired with proper speakers - it will sound exactly as gain stage in front of it .
accent is on "if paired with proper speakers" .
no-one can expect miracles from 25W/8R amp .
name of the game is FW , not 75-th W
so - we are speaking apples and oranges here - 78 posts and counting ........
if paired with proper speakers - it will sound exactly as gain stage in front of it .
accent is on "if paired with proper speakers" .
no-one can expect miracles from 25W/8R amp .
name of the game is FW , not 75-th W
so - we are speaking apples and oranges here - 78 posts and counting ........
- Status
- Not open for further replies.