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Joachim Gerhard Filter Buffer for ES9022

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Yep. Its more apparent on some tracks than others. Listening for short bursts back and forth also makes it hard to pick up the differences. Listen for a few minutes though and every time you're switching back to the buffer.

Now I have to make the dac and filter into a new chassis, the plank-of-wood chassis ain't gonna work with mains voltages to the Tx!

Fran
 
I built a shunt to run my filter - but I'm curious: what is everyone else using?


Fran

I am using this super reg to power the buffer.

B924B58E-1B06-4E67-A554-AABE5A0CA967-56446-000031DF5BAC7AC1_zpsc06cacf5.jpg
 
The active circuit is a cascoded JFET follower.
The follower JFET (BF862 upper) is cascoded and see a constant Vds pretty independent of output voltage.
The lower is a cascoded current source.
As such, the circuit has good PSRR.

For my "kitchen radio" (otherwise known as Sisters' Series), I just use 7815 / 7915.
For a slight upgrade a LT1763/LT1964 on 78xx/79xx pin compatible PCBs.
Or the XEN miniature Cap multiplier.

:)

Even if you wish to use a shunt, your CCS current does not need to be more than 35mA.
A boostered TL431 would do.


Patrick
 
I just realised that the current values quoted in post #469, 470, & 476 were not well defined.

According to our record, the JFETs that Fran has have Idss of around 14mA.
So thet figure of 28mA he was referring to in post #469 was for one PCB, or two single-ended channels.

And I was misled by the phase he used "on each leg".
So the numbers I gave in post#470 and in #476 were for one channel.

Thus, for 2 single-ended channels, or one PCB, the max current consumption can be about 50mA.
If you then choose to use a shunt regulator, the current source should be delivering minimum 60mA.
(Some of you will of course argue that even 55mA is sufficient.) ;)


Sorry for causing any confusion,
Patrick
 
EUVL - you are 100% correct, that is for 2 channels. 28mA for each polarity.


I thought I'd throw up a pic of my almost finished build. I'm using EUVLs 9022 dac (run on batteries) and the filter run from the salas shunt (the old hypnotise B1 boards butchered a bit). The other bits are for charging the batteries.

I had a bad mistake. When I reassembled everything I had no sound and DC offset from the DAC. I fried the 9022 - easier to do than you think with the batteries. After some advice and instructions from EUVL (thanks again!) I managed to remove the dead 9022 and replace it.

All is good, and I can tell you it sounds great with a shigaclone transport.


Fran
 

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