Thank you guys. I am learning some good stuff here.
It looks like the Burning Amp Complementary output stage boards from the store would be a convenient way to experiment with adding pairs...since they have mosfets, source and gate resistors on them and nothing else. Just hook this board up the the F5 board sans mosfets and bias.
It looks like the Burning Amp Complementary output stage boards from the store would be a convenient way to experiment with adding pairs...since they have mosfets, source and gate resistors on them and nothing else. Just hook this board up the the F5 board sans mosfets and bias.
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Sorry Itsmee,
but I think you got it wrong. Common drain connection means that input and output have the drain as a common node i.e. input on the gate, output on the source. Such a connection is also known as source follower.
And that's not the case with F5.
In F5 output stage the input is on the gates but the output is taken from the drains which makes it common source topology.
It's all nicely explained in F5 manual (pages 7 & 8) :
http://www.firstwatt.com/pdf/prod_f5_man.pdf
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I knew it was incorrect before I posted.
I wasn't trying to be technically correct, only trying to point out the difference between the two; typing source follower and common source probably wouldn't have made it clear to a newbie.
Maybe I should have typed 'The BA2 output board presents its source to the load,where as the F5 presents drain to the load'
I wasn't trying to be technically correct, only trying to point out the difference between the two; typing source follower and common source probably wouldn't have made it clear to a newbie.
Maybe I should have typed 'The BA2 output board presents its source to the load,where as the F5 presents drain to the load'
You may wish to read the comments made by Spencer on his website FET Audio | Hi-End Audio Projects
Upon adding more Mosfets "Sound wise, it is more powerful than the F5 original due to higher current output and more pairs of mosfet is used. Overall the sound is smoother and warmer than F5. Nelson said this amp sound more relax!"
Upon increasing rail voltage to 32V "The conclusion is that the distortion is lower at 32V and higher at 22V supply. With no surprise, this set sound the best after adding the Solen 1mH coil in the power supply (CLC) filter."
Upon adding more Mosfets "Sound wise, it is more powerful than the F5 original due to higher current output and more pairs of mosfet is used. Overall the sound is smoother and warmer than F5. Nelson said this amp sound more relax!"
Upon increasing rail voltage to 32V "The conclusion is that the distortion is lower at 32V and higher at 22V supply. With no surprise, this set sound the best after adding the Solen 1mH coil in the power supply (CLC) filter."
Hikari1 has mentioned that imaging and focus are more important than bass and drive, so there's possibility that he can hear this capacitance issue (or probably matching issue).
It is a trade-off, mostly affected by taste. And F5 doesn't have drive issue as much as single ended Alephs so the extra drive benefit may be less important than the micro detail audible differences, even tho this micro difference can only be heard by those with sensitive ears imo.
Although I haven't compared the single pair version vs. multiple pair version at same overall bias yet I am thinking that a lot of the "more relaxed, more powerful, smoother" reaction to the multiple pair versions of the F5 come from more bias. It's not really fair to compare a single pair F5 biased at 1.3A to a multiple pair F5 biased at 2.5A and say the differences are because of the addition of mosfets...
I was more interested in understanding the differences between single and multiple pair at same bias, which you guys have explained well.
But I guess that's the point...more pairs usually equals more bias.
My single pair F5 is biased at 1.8A now...I wonder how much more bias I could get out of it w/multiple pairs. The heat being more evenly distributed over multiple mosfets might let me reach 2.5A...if not, and I can only get to say 1.9A then I have increased the number of mosfets (and added the potential downsides you guys have mentioned) for little to no increase in bias.
I guess we shall see. Trying to get ahold of matched pairs of 2SK1530-Y + 2SJ201-Y now...
I was more interested in understanding the differences between single and multiple pair at same bias, which you guys have explained well.
But I guess that's the point...more pairs usually equals more bias.
My single pair F5 is biased at 1.8A now...I wonder how much more bias I could get out of it w/multiple pairs. The heat being more evenly distributed over multiple mosfets might let me reach 2.5A...if not, and I can only get to say 1.9A then I have increased the number of mosfets (and added the potential downsides you guys have mentioned) for little to no increase in bias.
I guess we shall see. Trying to get ahold of matched pairs of 2SK1530-Y + 2SJ201-Y now...
That's good info. I have the 5U case from the store. I'd be happy with 2.5A.
Is it wise to remove the limiters like in the F5T? I don't know how much current a dual pair at 2.5 will push, I think the current limiting kicks in at 10A. I would rather keep it but bumping up against the current limiter all the time would not be wise I think. Probably lead to smoking the amp.
I knew someone would say this. I have heard a few single driver designs...some have been interesting but all have been bass shy. Iam sure some of the larger horns sound good but they wont fit in my room. Some of the better ones have an almost planar like smoothness where all the sound is really unified...and to tell you the truth I didnt really like it. It was interesting but it seemed more of a novelty to me. Perhaps I am just used to regular speakers.
Possibly Zu Audio, Cathedrals, or to do it for maximum bang for the buck, Audio Nirvana 15" (you won't be disappointed).
There are other options too.
If you keep looking I guarantee you will find something that will impress you.
Ps. Also check out Nelson's Open Baffle design with the 15" slot loaded firing down at the floor and fullrange on top.
There are other options too.
If you keep looking I guarantee you will find something that will impress you.
Ps. Also check out Nelson's Open Baffle design with the 15" slot loaded firing down at the floor and fullrange on top.
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