Would any experienced builder please confirm that I don't have to populate R4, R5, R6, R7 and K1 relay If I will use regulator pcb without protection / control board
I have another piece of good news for you.
A test team member has his proto fired up and working.
So the PCBs should be OK, thanks to Dave's immaculate work.
I shall release them next weel to the forum so that you can pre-order.
As you can see he is not using the current limiting circuit.
He is also on a special mission to test other output devices other than 2SK1530/2SJ201.
Distortion measurements next week if he can find time.
Herzlichen Dank Uwe.
The schematics of the standard circuit will be released once it has been tested.
I am busy arranging that right now.
Greg, please kindly get in touch by email.
Patrick
What are output power to distortion characteristics of the F5X when or as compared with the bog standard F5? Are these Identical to Nelson Pass' F5 Manual 1% 1khz;25Watts or obviously dramatically improved, especially at higher power such as 25W? I saw something about 2nd, 3rd harmonic distortion at -100 and -120db but at what output. Is the standard and/or cascoded front end F5X suitable to drive Quads' (at 25-40W p/ch) with low distortion?
..Thank you!
..Thank you!
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I may be an overly ambitious neophyte, but I really want to build my own balanced amplifier. I have some DIY electronics experience (more breadboard and Arduino experimentation than soldering and circuit board work at this stage). I was going to build an F5T (and may yet someday), but I really want a balanced topology to compliment my otherwise balanced audio system.
In reading Nelson's article about the various F5 versions, I couldn't help but be directed to your work here, which is awesome.
I figure a balanced amp will be challenging enough to be educational and satisfying enough to keep me engaged... but I don't want a project that is so difficult (or poorly documented) that it outpaces my ability (and thus causes me to give up on it after hitting too many unanswered questions or dead-ends in the build notes). This project seems to be one of the better-documented ones out there. So perhaps there is hope.
So I guess I'm looking for advice. Would I be biting off more than I could chew with a build like this? Should I start with a basic F5 or F5T and "work up to" something like the F5X?
Lastly, I suppose availability of the requisite parts and chassis becomes relevant. You mentioned the previous GB for the chassis and matched components was the "last-time" ... so I suppose I shouldn't hold my breath that such a thing will be forthcoming in 2020 or 2021?
Thanks again for all the information and detailed plans and guides. I'm learning a lot just reading the forums.
Oh, and... Happy New Year!
That's fair. Thanks for the candor.
What stereo amplifier design would you recommend for beginners? Something like the Pass Amp Camp #1?
What stereo amplifier design would you recommend for beginners? Something like the Pass Amp Camp #1?
LM3886. Many kits around for very little money.
If that is too easy for you then :
UDNeSS, or You don't need Semisouth's
Patrick
If that is too easy for you then :
UDNeSS, or You don't need Semisouth's
Patrick
The whole point about a fully differential amplifier like F5X is not about power, but about distortion spectrum.
With the same number of output devices, you can also build a single ended amplifier with the same output power.
But the latter will most certainly have higher even harmonics content.
Assuming of course your device matching is good.
To understand why a fully differential JFET front end has such low distortion, I suggest you read the excellent website of Pavel Macura :
Distortion in JFET input stage circuits
Patrick
With the same number of output devices, you can also build a single ended amplifier with the same output power.
But the latter will most certainly have higher even harmonics content.
Assuming of course your device matching is good.
To understand why a fully differential JFET front end has such low distortion, I suggest you read the excellent website of Pavel Macura :
Distortion in JFET input stage circuits
Patrick
That question was answered 8 years ago in the same thread !
F5X -- the EUVL Approach
THD -104dB. H2 20dB lower than H3. H4 <<-140dB; H5 -125dB.
Patrick
F5X -- the EUVL Approach
THD -104dB. H2 20dB lower than H3. H4 <<-140dB; H5 -125dB.
Patrick
I also need to use the search function, like everyone else.
Start with the build thread for the documents in the public domain.
F5X -- the EUVL Approach - The Build Thread
Patrick
Start with the build thread for the documents in the public domain.
F5X -- the EUVL Approach - The Build Thread
Patrick
thanks for the link to the other thread.
Just a last question:
original F5 is with irfp140/9240 higher transconductance
F5X is with 2SK1530 - 2sj 200, that have lower transconductance and lower VGS resulting in lower Open loop gain of the amp, how do you cope with it? less negative feedback?
Pass used 2SK1530 - 2sj 200 type mosfets in a "F5" amp called F7 he had to add positive current feedback to compensate for the lower open loop gain...
Just a last question:
original F5 is with irfp140/9240 higher transconductance
F5X is with 2SK1530 - 2sj 200, that have lower transconductance and lower VGS resulting in lower Open loop gain of the amp, how do you cope with it? less negative feedback?
Pass used 2SK1530 - 2sj 200 type mosfets in a "F5" amp called F7 he had to add positive current feedback to compensate for the lower open loop gain...
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