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Joachim Gerhard Filter Buffer for ES9022

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#607
voxxonline said:
Guys as I understand you advise using power supply regulator with buffer ?
Click to expand...

As I understand it, the XEN team advises to use batteries with the buffer.
But also, since batteries are not everybody's cup of tea, you can use the low impedance, low noise power supply regulator of your choice. For best results, use a bipolar supply for each channel.



Another question about source impedance before the buffer: What source output impedance is recommended (or ok) before the buffer?

I really thought about this for some time now, but with my limited knowledge, I´m not coming anywhere anymore. So any help is appreciated.

The 9022/9023, for which the buffer is build, should have an output impedance in the range of 220-240 Ohms, which is, (I guess) average for a home audio source. So basically, could it be integrated after any audio source with reasonably low output impedance?

To be more specific: I am thinking about how to integrate the filter-buffer with my SEN I/V stage for the BIII DAC. I´m using the SEN single ended at the moment, but I am working on a balanced setup right now. I used transformers for unbalancing the signal in the past (via Sowter 3575 with 10k:10k windings) so I would like to use them again with the balanced SEN.

I first thought about using the buffer after the transformer, to buffer its high impedance of the secondaries. But then I´m not sure if the passive filter part of the buffer would still be functional. So: would it work?
I´m sorry if this is maybe a dumb question but I didn´t study electronics, feel free to educate me.

Another possibility would be to use the Lundahl LL 1527 transformers for unbalancing, which I have lying around. They have a "static primary and secondary resistance" of around 50 Ohm. So much lower than the sowter 3575. Consequently, it should work with the filter buffer, but I´m not sure if the SEN can drive such low impedance properly (I´m using Riv=180 Ohm at the SEN).

A third possibility would be to use two filter buffers (four channels, one for each phase) before the transformers on the balanced signal. But this doubles the complexity, and would leave an unbuffered signal after the sowter transformer...

So, I like bandwidth limiting (and consequently the idea of a filter), it makes longterm listening more enjoyable in my experience. And I know the transformers provide some bandwidth limiting of their own, but I guess it would be nice if I could properly implement an active buffer with them, to not loose the "drive and slam" that the SEN I/V stage brought back to my system.
 
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#608
This filter in particular is designed for the ES9022, which has Zout in the order of 240R.
You can of course used it for something similar, such as PCM5102.

For anything else, such as SEN, I would not use the filter as is for a Zout of higher than 1k.
If your Zout is higher, you can redeisgn the filter accordingly, or add a buffer in between.

This is only meant to explain how to make it work.
It does not imply by any means that it is the optimal solution.

I don't use transformers. So no comment on those.


Patrick
 
#609
Thank you Patrick,

I did dome more reasearch now. I guess the best way for me to use it - with line transformer - and the combined knowledge of diyaudio 🙂
->SEN with 240R and 4.7 nF Riv/Civ termination (or slightly different, doesn´t matter so much apparently)
-> Two Filter-Buffers PCBs for balanced operation. Presents low impedance source to
-> 10k/10k unbalancing transformers with a constant load on secondaries by
-> potentiometer (don´t know which impedance yet)
-> buffer to poweramp

Any objections? I´ll see how this works out....
 
#614
kumori said:
As I understand it, the XEN team advises to use batteries with the buffer.
But also, since batteries are not everybody's cup of tea, you can use the low impedance, low noise power supply regulator of your choice. For best results, use a bipolar supply for each channel.
Click to expand...

I'm going to use two Sigma 25 +15v supplies. Wired up correctly you can get +/-15v and 0v that go to the buffers +Vs, --Vs, and 0v points.

Are you sure two bipolar supplies are required? I would think if you were going balanced you'd need two supplies. Maybe I'm misunderstanding your answer.
 
#615
Mull3t said:
I'm going to use two Sigma 25 +15v supplies. Wired up correctly you can get +/-15v and 0v that go to the buffers +Vs, --Vs, and 0v points.

Are you sure two bipolar supplies are required? I would think if you were going balanced you'd need two supplies. Maybe I'm misunderstanding your answer.
Click to expand...

Ok, I guess this should also work. You can only use one supply with -15v/0v/+15v and connect to the designated points.

For the two supplys (I might need some help here, my memory is not that good anymore), I read somewhere in this thread, that it might be beneficial to supply every channel (there are two on the pcb) with its own supply (two times -15v/0V/+15v, one for every channel).

There is a 220uF/10R input filter at each supply line. If i understood it correctly, it is ok to remove the 10R resistor and attach the mono-supplies to the pad of the former 10R. However, I did not do this and can say nothing about whether it is worth a second supply.


Then use 180R. No need to change to 240R.
Click to expand...

Alright then, thank you.
 
#618
#619
On top side I find a diff... are the two 0 and 100R just moved to the right or did they also change place?
 

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