Advice needed with a discrete JFET differential to SE input buffer

Hi,

I am trying to do a discrete differential to SE input buffer for my active crossover. After good experience with J113 based buffers, I found this design (CD53_CFP_DiscreteOutputStage.jpg) somewhere on google picture search and adopted it. Two things I would like to improve:

1. Active load for the LTP input. I tried to replace R9/R12 with a current mirror, but had no luck. Could not get a working sinus signal
2. Simple solution to get rid of the output cap C1.

I would be happy for any suggestions.

Regards,
Michael
 

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  • Concept_HDAM_CD53.asc
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That depends on what you want to achieve.
In the original version of the XCEN, the circuit is much simpler.
The XCEN -- Balanced to Single Ended Converter

But it does drift some mV with temperature, for me too much.
So as explained in the pdf document, things are added to ensure good thermal tracking.

Of course you can also use a servo, if you count an opamp as one component.
O just accept the few mV offset drift.


Cheers,
Patrick
 
Absolutely, the THD figures really look good. Below 0.00x. Hmm, I wanted to move over to SMD since good through-hole parts become more and more obsolete. I might give it a shot 🙂 Is there any reason you use MOSFETs instead of BJTs?

Michael
 
> Is there any reason you use MOSFETs instead of BJTs?
Look at the values of R22/C1.

If you download the pictures of the original XCEN 2018, it can be a good basis for your PCB deisgn.
Only a couple of minor changes necessary.
Pretty sure you can manage.


Patrick
 
Finally I got the PCBs, that Patrick sent to me up and running. What should I say: This is clearly an improvement over all Opamp based circuits I tried so far. A highly transparent component, with clarity and a lot of more detail.

Thank you very much Patrick 🙂
 

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  • XCEN-SE_Crossover.jpg
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