Zen -> Cen -> Sen, evolution of a minimalistic IV Converter

I have pcm1794 based dac using OPA1611 /12
It Is better than NE5534 / 32 but would like very much to see your Implementation with Sen

Thanks for the update.
On my side I completed the integration of your modified SEN based on 2SK2145 with a PCM1792A and it works very well.
Those JFET are still available so I have one question for you, why not pursuing in this way with JFETs available?
 
It is not very complex, I use the SEN principle & schematics and replace the original JFET by 2SK2145 with 2x SK2145 JFET in parallel to accommodate the current delivered by the PCM1794.
It is in the end equivalent to 4x JFET as each 2SK2145 include 2x JFET.
I am using a mono configuration and summing the output of the DAC so the output current is x2 on my side but with a stereo configuration and only 7.8mApp output current, most likely one 2SK2145 is enough per branch (no need to put 2 in parallel).
I have been sorting all the 2SK2145 I have to couple them in the best way. I am using a heatsink to thermally couple them.
 
With 7.8mApp current, I would be using 16mA bias at least.
That already means 2x 2SK2145BL in parallel.
But 2SK2145BL, even with 9V across it, dissipates close to 100mW per FET.
Too close to max. allowable dissipation for me.
Which means 4x 2SK2145GR in parallel, with matched Idss.

At least that is what I would do.
But of course you have it working with 2x //.
Which is what counts.


Cheers,
Patrick
 
After 9 years and 2000+ posts, people are still asking for PCBs.

The bad news is that we have none left, and cannot provide JFET sets.
The good news is that we are working on something new along the line of this :
Zen -> Cen -> Sen, evolution of a minimalistic IV Converter

When proven successful, we shall publish in a new thread.


Thank you for your interest,
Patrick

Patrick,

That’s great, thanks for the heads up!

Cheers,

Greg
 
With 7.8mApp current, I would be using 16mA bias at least.
That already means 2x 2SK2145BL in parallel.
But 2SK2145BL, even with 9V across it, dissipates close to 100mW per FET.
Too close to max. allowable dissipation for me.
Which means 4x 2SK2145GR in parallel, with matched Idss.

At least that is what I would do.
But of course you have it working with 2x //.
Which is what counts.


Cheers,
Patrick


Anybody have SEN circuit with 2SK2145 ? It have Y, GR and BL models.Which one is ideal to make SEN ?

I plan to use it for balanced PCM1704 DAC.

Thank you.
 
Help to use SEN converter

Thank you for the information. I plan to use them like on the picture. Do i have to add any other stage or change to something in that case?

Best Regards
Z
 

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The SEN IV has an output impedance of 2.8k ( = Riv ).
If you wish to use it to drive a lowish impedance load, you should add extra buffers.

The THAT 1240 has different effective Zin at the +Vin and -Vin pins.
The values are relatively low compared with that of the SEN IV Zout.
The loading of the SEN IV output will of course not only be visible at the THAT1240 output.
It will also be noticeable at the balanced output.
I can only suggest you simulate in spice first before choosing your solutions.

The newer current-mirror IV converter does have a follower output stage and hence lower Zout (~6R).
A Simple Discrete Current-Mirror IV Converter, à la AD844

As far as I can tell, your XLR pin assignments are not according to industry standard.

I have to admit I do not quite understand why you want to go to the complexity of SEN IV.
And then use a opamp converter downstream.
You might as well just use an opamp IV.


Wishing you success,
Patrick
 
I can only suggest you simulate in spice first before choosing your solutions.

I have to admit I do not quite understand why you want to go to the complexity of SEN IV.

I don't know simulate of DACs. I have this type dac connections by 4 Pcs PCM1704 and looking to how can i use it with SEN converter. I don't want to complexity but search to use them together. I planed to use SEN converter couse of better sound quality from the opamp converters.
 
If I can be forgiven for being honest, I advice you to consider some other IV circuits.

The SEN IV has certain limitations that requires understanding of electronic circuitry.
If my answer in post#2152 does not make much sense to you, then I am afraid that you will not be happy with the results in the end.
It is also likely that you might encounter oscillations from your 4x individual floating power supplies.

Maybe the Zen I/V from Nelson Pass is a better solution for you.
At least it uses fixed rails, though it also has the same the problem with the THAT1240.
Zen I/V Converter | Pass DIY

See also :
https://www.by-rutgers.nl/PDFiles/Mature IV-converter.pdf


Cheers,
Patrick
 
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If I can be forgiven for being honest, I advice you to consider some other IV circuits.

The SEN IV has certain limitations that requires understanding of electronic circuitry.
If my answer in post#2152 does not make much sense to you, then I am afraid that you will not be happy with the results in the end.
It is also likely that you might encounter oscillations from your 4x individual floating power supplies.

Maybe the Zen I/V from Nelson Pass is a better solution for you.
At least it uses fixed rails, though it also has the same the problem with the THAT1240.
Zen I/V Converter | Pass DIY

See also :
https://www.by-rutgers.nl/PDFiles/Mature IV-converter.pdf


Cheers,
Patrick
I don't have to use THAT 1240 it just optional. So there is no way to use SEN converter with this dac connection without understanding electronic circuitry... I bought 16 Pcs mathced 2sk170bl but seems to i have to look for another options.
 
After 10 years, I have yet another PM asking me about power supplies for the SEN IV.

As have been mentioned here many times, you need floating power supply for each SEN.
They must be independent of each other and have np connection to Gnd.
If you have two channel single ended (RCA out), you will need two separate supplies.
If you have two channel balanced (XLR), you will need 4 separate supplies.
These supplies will swing with the output signal.
The best solution for floating supplies are batteries.
There are many working examples posted in this thread.

Please post your question here instead of sending me PMs.


Thanks,
Patrick
 
Hi,

I got my matched 2SK170BL jfets. I decided to make more easy PCM1704 Dac circuit after talk with Patrick. So that will be standard application circuit which attached. I will replace OPA627 directley with SEN I/V converter then OPA2134 post filter come after SEN am i right?

I wonder also matching values between 0.02 - 0.07 differences will be any problem? Like 9.39 vs 9.32.

Best Regards
Thank you
 

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At the beginning I have to say that I am a noob. My English is also poor, but google translate helps me:)
I read the thread but for the above reasons I have no knowledge and skills to do what I planned.
I need help to adapt the CEN to the DAC TDA1541A.
I saw several solutions (e.g. D1) and now I use an analog stage on opamps.
I know that I need to compensate offset on I-out in the TDA with potentiometers.
The DAC I have has the option of mounting pull-up(bias) resistors (R25, R33 in the picture) 2k5 which "inject" 2mA to these outputs. After using them I had a 30mV offset. It's not good as far as I understand. Could someone show me a solution that will work and adjust the CEN to the TDA1541 DAC?
Thanks a lot:)
 

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