Finally something to show (off with)...
PCB is for the DiyAudio F6 circuit (IRFP240 version).
And as you can see, major inspiration from the DiyAudio F6 pcb!
Although, I threw in the Hitachis to see what they can do (pins 2 and 3 cross connected).
Only basic tests so far, but does not look too bad...
All tests with the Hitachis. Gate resistors 220R, otherwise they will oscillate.
Frequency response:
5kHz square wave, red input, blue output:
20kHz square wave, red input, blue output:
20kHz 1W 8R, guess which is input and which is output...
🙂
PCB is for the DiyAudio F6 circuit (IRFP240 version).
And as you can see, major inspiration from the DiyAudio F6 pcb!
Although, I threw in the Hitachis to see what they can do (pins 2 and 3 cross connected).
Only basic tests so far, but does not look too bad...
All tests with the Hitachis. Gate resistors 220R, otherwise they will oscillate.
Frequency response:
5kHz square wave, red input, blue output:
20kHz square wave, red input, blue output:
20kHz 1W 8R, guess which is input and which is output...
🙂
damn ooking good looking !
besides pretty decent workmanship , I see you were smart enough to choose tried iron
besides pretty decent workmanship , I see you were smart enough to choose tried iron
Hi there folks - 2 questions if someone can help?
The Jfets I've got for the front end are loosely matched, K170's at Idss of 8.2 and 8.6, and the J74's are 7.7 and 7.9. How do I go about calculating the correct amount of degeneration to apply to the K170's to more closely match them?
Secondly, there's a great article that was written about this exact process by one of the members of Diyaudio (Juma? Evul? I don't remember...), that wen't into some fairly intricate detail around matching the curves of the devices as well. Does anyone know the document I'm talking about and where I could find it? It might prevent me asking any further questions...
Thanks!
The Jfets I've got for the front end are loosely matched, K170's at Idss of 8.2 and 8.6, and the J74's are 7.7 and 7.9. How do I go about calculating the correct amount of degeneration to apply to the K170's to more closely match them?
Secondly, there's a great article that was written about this exact process by one of the members of Diyaudio (Juma? Evul? I don't remember...), that wen't into some fairly intricate detail around matching the curves of the devices as well. Does anyone know the document I'm talking about and where I could find it? It might prevent me asking any further questions...
Thanks!
though , if you include 22R trimpot between sources (wiper goes to xformer) , that's pretty good to go
Thank you ZM. I'll go and do some digging through that thread.
I had thought to try and get to a mathematical solution for degeneration as I haven't a distortion analyser to 'tune' the H2/H3 to the lowest level (or to the 'best' mix to my hearing).
My next though is to just throw them in and fix my mind to be happy with the result instead of fixing the parts 😀
I had thought to try and get to a mathematical solution for degeneration as I haven't a distortion analyser to 'tune' the H2/H3 to the lowest level (or to the 'best' mix to my hearing).
My next though is to just throw them in and fix my mind to be happy with the result instead of fixing the parts 😀
Actually - it wouldn't be too hard to check empirically as to what the degeneration resistor values would be on the PCB. Given the local stores dont have 22K trimpots on hand (and clearly, neither do I!) that might be the best way forward...
eh? What? I can't hear you!
trimpot - 22R , as 22 Ohms
K means KiloOhms
slight difference it is ....... around 1000 times
K means KiloOhms
slight difference it is ....... around 1000 times
I'm not as funny as I think i am apparently!
I was trying to make light of me not seeing that and then not hearing the amp...
Perhaps I need to use more emoticons (and by that stage of the evening perhaps less good whisk(e)y.)
I was trying to make light of me not seeing that and then not hearing the amp...
Perhaps I need to use more emoticons (and by that stage of the evening perhaps less good whisk(e)y.)
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Still lots to do to fine tune everything,
but already got that
(1kHz/1W/8R)
from this http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-605.html#post4303131
...which is nice... 🙂
but already got that
(1kHz/1W/8R)
from this http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-605.html#post4303131
...which is nice... 🙂
Still lots to do to fine tune everything,
but already got that
(1kHz/1W/8R)
from this http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-605.html#post4303131
...which is nice... 🙂
Is is set to dominant 3rd?
I would not say "set" for a dominant 3rd.
But at the moment is has quite strong 3rd. Next task is to find the cause and see if I can do something about it.
I like the low 2nd harmonic though...
