I have been asked again by PM about my reply in post #6.
a) Please post your question here in the future. People do not expect perfect English. And for me no excuse either.
b) People who knows me knows that I do not have time to nurse every project from a to z.
And epecially those I have not built or am not building.
If I give you an idea, and you cannot take the idea and realise it on your own, then I propose you find something else to build.
My sincere apologies for being rude, but I'd rather be honest.
c) If you wish to build a preamp based on the F5 topology, you may have a look at these threads :
http://www.diyaudio.com/forums/pass-labs/171827-f5-preamp-simulation-shoot-out.html
http://www.diyaudio.com/forums/pass-labs/125893-preamp-ideas-f5.html#post1555551
http://www.diyaudio.com/forums/pass-labs/244106-lsk-pre-baf-2013-a.html
If you have questions, please post it directly at those threads, so that people who have built those circuits can help you.
I myself have not built any of them, as I mostly only build balanced circuits.
Thank you for your interest in any case,
Patrick
a) Please post your question here in the future. People do not expect perfect English. And for me no excuse either.
b) People who knows me knows that I do not have time to nurse every project from a to z.
And epecially those I have not built or am not building.
If I give you an idea, and you cannot take the idea and realise it on your own, then I propose you find something else to build.
My sincere apologies for being rude, but I'd rather be honest.
c) If you wish to build a preamp based on the F5 topology, you may have a look at these threads :
http://www.diyaudio.com/forums/pass-labs/171827-f5-preamp-simulation-shoot-out.html
http://www.diyaudio.com/forums/pass-labs/125893-preamp-ideas-f5.html#post1555551
http://www.diyaudio.com/forums/pass-labs/244106-lsk-pre-baf-2013-a.html
If you have questions, please post it directly at those threads, so that people who have built those circuits can help you.
I myself have not built any of them, as I mostly only build balanced circuits.
Thank you for your interest in any case,
Patrick
I ordered a few pairs from this seller after reading this, received them today. Measured 2 of the 170GR and they look very genuine to me 🙂
Attachments
Most probably, but I already have 2 outstanding projects to finish so this will likely be a winter project for me, but thanks for your design in advance 🙂.
BTW, I have some 2SK2013 and 2SJ313, are they good alternatives for the output device?
In principle yes, but they have lower Vgs.
So apart from having to lower the JFET drain resistor values, you will have less negative feedback (about 5dB).
Patrick
So apart from having to lower the JFET drain resistor values, you will have less negative feedback (about 5dB).
Patrick
Yes, and in principle you can adapt the circuit to your headphone impedance.
The limits are :
1) Vds for the JFETs (absolute max. +/-24V)
2) Dissipation of the JFETs (I would not go over 150~200mW)
3) Dissipation of the MOSFETs (limited by the heatink)
4) Dissipation of the 500R feedback resistor (+/-24V output sinewave would mean 0.4W).
I assume you would not turn it on too loud to kill your headphone. 🙂
Patrick
The limits are :
1) Vds for the JFETs (absolute max. +/-24V)
2) Dissipation of the JFETs (I would not go over 150~200mW)
3) Dissipation of the MOSFETs (limited by the heatink)
4) Dissipation of the 500R feedback resistor (+/-24V output sinewave would mean 0.4W).
I assume you would not turn it on too loud to kill your headphone. 🙂
Patrick
Patrick, My JFETs Just arrived this morning from 'alweit'.
The two closest pairs Idss values are 7.81 for one pair and 7.82 for the other pair.
And I swapped out the 15V transformer on my supply to a 12V, so now my rails are approx +/- 14.8V under load.
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For 7.8mA Idss, you can use the drain resistor values as is (820R // 5k trimmer).
You can either use a simple cap multiplier, or 7812/7912 as regulator.
Capacitance Multiplier Power Supply Filter
(Fig. 3, replace BD139/140 by BC550/560, TIP35/36 by D44/45H11.)
To use the Nazar regulator in pot #60 you need more voltage headroom, so 15Vac secondaries 30VA per channel minimum.
Patrick
You can either use a simple cap multiplier, or 7812/7912 as regulator.
Capacitance Multiplier Power Supply Filter
(Fig. 3, replace BD139/140 by BC550/560, TIP35/36 by D44/45H11.)
To use the Nazar regulator in pot #60 you need more voltage headroom, so 15Vac secondaries 30VA per channel minimum.
Patrick
Thanks Patrick. I've already built the supply using Rods version of a capacitance multiplier and it seems to be working well with virtually no ripple when viewed on my scope.
By the way, why do you suggest '(Fig. 3, replace BD139/140 by BC550/560, TIP35/36 by D44/45H11.)'?
By the way, why do you suggest '(Fig. 3, replace BD139/140 by BC550/560, TIP35/36 by D44/45H11.)'?
1) You do not need the current / power. He was using it for power amps.
2) The ones I name have higher bandwidth, higher hfe, and lower noise.
Patrick
2) The ones I name have higher bandwidth, higher hfe, and lower noise.
Patrick
I figured I'd make it as described so I could reuse it in some other higher power project if required. But the lower noise is interesting. I'll use it as is for the time being, and if I like the prototype amp, I may follow your advice and build a more modest supply for my final version.
PS. thanks for your help and really prompt replies. Really appreciated.... particularly as my knowledge is somewhat limited.....at least it means I'm always learning.
PS. thanks for your help and really prompt replies. Really appreciated.... particularly as my knowledge is somewhat limited.....at least it means I'm always learning.