All PCBs were 1oz copper (35u thick).
Is there a bipolar 4.3 mentioned on my web site? I seem to remember that 4.2 was the last bipolar version, 4.2 schematic and Gerbers are available on my web site.
Which one to build? Is HPS6.1 better than 4.2? I have BF862 fets and also low noise bipolars. There is no dimensions information in your 4.2 gerber file.
There is no "better", there are only requirements and preferences. 4.2 is extremely low voltage noise (0.28nV/rtHz), has 5-10pA/rtHz (or larger, depending on the transistors you are using) input current noise, up to 100nA DC input current (after nulling, due to the thermal drift) and is rather power hungry (runs pretty hot). 6.1 has higher noise (0.4nV/rtHz), virtually zero input current noise (can be used with low output MM cartridges or high output MC cartridges), virtually zero DC input current and can be fed from batteries. Make your choice depending on your cartridge and preferences. Myself I am currently using 6.1 with a Benzo Micro low output MC cartridge.
Board size is 10.5 x 3.2 inches.
3.5mV is not a low output MM. Barring some possible exceptions, one should NOT use a bipolar amp with MMs. The noise current and the high impedance of the MMs are generating plenty of noise, to largely exceed the amplifier very low voltage noise. For MMs use 6.1, for low output MCs you can use either 6.1 or 4.2.
Yes, everything is 1oz. If something helps with dissipating heat that's the ground plane, and the copper thickness id pretty much irrelevant. Thick copper traces are useful for high currents. Does not apply here.
Above, it is 6.2 that has 0.4nV/rtHz (6.1 is about 0.33nV/rtHz), 6.2 can be fed from batteries (6.1 still needs a stiff raw power supply, as much as 4.2), and it is 6.2 I am currently using, sorry for the confusion.
Ovidiu,
At the time you considered the HPS5.1 to be the finest of your phono amp designs. With the advent of your more recent iterations and more time to listen/reflect upon the previous ones, which do you now consider to be your favourite and why?
Regards,
HPS 6.1 implemented an active load (current source) in the low noise gain stage and a new servo. As a result, the PSRR increased dramatically, power supply low noise buffers are no longer required. The construction is about half the size of HPS 5.1.
HPS 6.2 builds on the HPS 6.1 topology, but lowers the low noise gain stage bias current at levels compatible with battery supplies; as a result, it runs cool (all others are running rather hot) and the output DC fluctuations of thermal origins are no longer an issue. All these against a slight noise penalty of under 0.1nV/rtHz (compared to HPS 5.1 and HPS 6.1).
HPS 6.2 builds on the HPS 6.1 topology, but lowers the low noise gain stage bias current at levels compatible with battery supplies; as a result, it runs cool (all others are running rather hot) and the output DC fluctuations of thermal origins are no longer an issue. All these against a slight noise penalty of under 0.1nV/rtHz (compared to HPS 5.1 and HPS 6.1).
Hi Ovidiu,
Hope all is well
Wondering how this design got past DRC at jlcpcb.
I am looking at this HPS6.2-5 layout, I see a top/via-pad trace clearance of 2.5mil @~ 3312,3037 mil, but your area fill clearance on the bottom around that pad is 10 mil
U301,401 pin 14
Obviously it works, good to know they are fine with that clearance.
Another thing, you are specifying a X?R class 2 dielectric for C216/316, which is in the signal path, Isn't that a audio snobbery no-no?
Take care
Rick
Hope all is well
Wondering how this design got past DRC at jlcpcb.
I am looking at this HPS6.2-5 layout, I see a top/via-pad trace clearance of 2.5mil @~ 3312,3037 mil, but your area fill clearance on the bottom around that pad is 10 mil
U301,401 pin 14
Obviously it works, good to know they are fine with that clearance.
Another thing, you are specifying a X?R class 2 dielectric for C216/316, which is in the signal path, Isn't that a audio snobbery no-no?
Take care
Rick
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