Another beautiful looking head amp, Aatto! What are you using for a heat sink? Are you keeping the bottom wide open for ventilation? Any additional noise from having the SMPS in the case? I also would love to hear your take on the sonic differences between your ZVN4306 build versus this one with the IRF10. Gathering ideas for my eventual desktop build...
Thanks
for heat sink i use a 100x35mm heat sink i bought from ebay, and the bottom piece have some ventilation openings by the heat sink and by the board itself since JFETS and specially the resistors tends to run warm, i do not have a build with ZVN4306 at the moment to do a side by side comparison but it has the same character since I use the same BF862 JFETs, it maybe my imagination but i think IRF10 build is a little louder, the only thing i noticed is that the input 10uF Silmic II caps can emphasis some low mid freqs on certain records ( depends on the record ) not on everything, which is not that noticeable but it's there, it's not annoying enough to push me to switch it back to WIMAs.
as for using SMPS, the amp is dead silent, no noise no hiss or hum coming out of the cans when nothing is playing. going for laptop power supply was the best idea, they are dirt cheap, i got mine for 8$ with free shipping.
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You now know the secret of a dead silent PSU: start with SMPS at wallplug, go to cap Mx, follow with CRCRC.
I have a new SE Class A preamp design that just finished tweaking and testing last night. It is capable of 40vpp to drive the most difficult unity gain power amps. The distortion levels and profiles are amazing and made possible by using a SMPS and cap Mx CRCRC PSU. I added a DC step up after a 12v SMPS to get 45v to 48v needed.
AKSA's Lender Preamp with 40Vpp Output
Look at this measured FFT - and this is running from a wallplug. Look at the absence of any peaks near line mains 60Hz/120Hz/180Hz. Noise floor is limited by sound interface (Focusrite Solo 2G).
Here is 20v p-p into 7k load:
Here it is driving a more typical level of 4vpp into 3.4kohmmload:
Who says you need a lot of transistors to achieve almost no distortion. Certainly 6 actives here works quite admirably.
Here is stereo preamp with step up, cap Mx, CRCRC. This is an all BJT design except for the constant current source which is a depletion mode n channel mosfet BSP129 (on left). On right is a DZT5401 PNP capable of 600mA.
I have a new SE Class A preamp design that just finished tweaking and testing last night. It is capable of 40vpp to drive the most difficult unity gain power amps. The distortion levels and profiles are amazing and made possible by using a SMPS and cap Mx CRCRC PSU. I added a DC step up after a 12v SMPS to get 45v to 48v needed.
AKSA's Lender Preamp with 40Vpp Output
Look at this measured FFT - and this is running from a wallplug. Look at the absence of any peaks near line mains 60Hz/120Hz/180Hz. Noise floor is limited by sound interface (Focusrite Solo 2G).
Here is 20v p-p into 7k load:
Here it is driving a more typical level of 4vpp into 3.4kohmmload:
Who says you need a lot of transistors to achieve almost no distortion. Certainly 6 actives here works quite admirably.
Here is stereo preamp with step up, cap Mx, CRCRC. This is an all BJT design except for the constant current source which is a depletion mode n channel mosfet BSP129 (on left). On right is a DZT5401 PNP capable of 600mA.
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i m building an Pass A3 clone, and i was thinking to use my Cavalli EHHA clone as a preamp but this looks very interesting. let us know.
thanks
A.
Hey drpro. I like your case and especially the dual headphone jacks (I really dislike adapters). Your M50s look almost as well worn as mine. I need to replace my earpads...how do you like the velours? Earlier tonight I actually finally got around to doing the removable cable mod on my pair. I mostly listen to headphones on the go, and now I can finally walk around without the heavy coiled cable slapping me around. 
I really enjoy the M50 bass with the PCA.
I really enjoy the M50 bass with the PCA.Attachments
Hi,
Quick question - the circuit diagram one page 1 shows the Vcc as 16V. Having purchased the pcb+smd soldered on from xrk I put together the remaining pieces on the board and now wanted to give it a quick test with some normal 9V carbon/zin batteries I found in the house. The voltage would be around 18V. Is that OK? I have used 25V caps for the power supply filters but not sure of the active devices etc and do not want to spoil the pcb.
Thanks.
Quick question - the circuit diagram one page 1 shows the Vcc as 16V. Having purchased the pcb+smd soldered on from xrk I put together the remaining pieces on the board and now wanted to give it a quick test with some normal 9V carbon/zin batteries I found in the house. The voltage would be around 18V. Is that OK? I have used 25V caps for the power supply filters but not sure of the active devices etc and do not want to spoil the pcb.
Thanks.
Those Nichicon 2200uF 16v rated caps work well with 9v alkaline batteries. It's just slightly over the rating and quickly plummets below 16v with some use. I have not had any problems. Don't worry about it.