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

[NicMac]

Originally Posted by EUVL

Seems that there are quite a few 9018 owners out there not entirely happy with their own IVs.

Yes, and I'm sure that a SEN layout stackable with the TPA Buffalo would make a recipe for success. Unfortunately, I'm not capable of doing this......
Nic

[EUVL]

There are many many nice sounding R2R DACs, like PCM63, PCM56, AD1865, PCM1704, ....
Why use Sigma Delta ?




Patrick

PS If it has to be simple then WM8741 or ES9022 is very hard to beat.
And we are planning to try PCM5102 later (this winter).

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[samoloko]

Originally Posted by EUVL

BTW, we got a CEN BJT (4 transistors, 3 PSUs) working.
Thermal coupling is crucial.
Quite a bit noisier than CEN or SEN (JFET).


Patrick

more noise but cap free - did you compare how sounds to SEN / CEN
maybe a schematic with more BJT and Rload will be less noiser
BTW what Is measured noise In real compared to simulation at post 95

[EUVL]

> more noise but cap free

If you have read and understood the article, you would agree the cap has a different role here than in e.g. Zen IV or D1.
Any distortion due to the cap has a lot less influence, if any at all.

> did you compare how sounds to SEN / CEN

Yes, but I will not make comments of my circuits against ones not from me.
Except only to say that my own default circuit for PCM1704 is still SEN.

> what Is measured noise In real compared to simulation at post 95

The actual noise measurements can be seen at the start of the thread.
-100dBV using 2x NiMH batteries 8.4V each, no filtering caps other than those in the circuit.
No exotic regulators either.

We also listen with headphones to compare one to another.


Patrick

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[samoloko]

Patrick

no I have not read article but thanks

what Is your default circuit for pcm1704

I was asking If you have measured noise of CEN with BJT opposed to simulation at post 95

[EUVL]

Default circuit for PCM1704 is SEN with R_iv = 2.2k.
Yes, you should read the article , especially if you want to adapt the circuit for your specific needs.

No, we have not measured the noise of CEN BJT.
I don't have access to Jan Didden's Audio Precision every evening.
But we have listened with headphone and compared to SEN, which we have measured.


Patrick

[Alexium]

Originally Posted by EUVL

There are many many nice sounding R2R DACs, like PCM63, PCM56, AD1865, PCM1704

Have you listened to them? Can you hear the difference between R-2R and delta-sigma?
What's the best value/price R-2R, in your opinion?

[EUVL]

I have a sample ES9018 here lying around, I have many versions of ES9022.
I also know 2 persons who have built both 9018 with D1 and 9022, and prefer the 9022 when properly done.
We also had various other DACs before, like AK4396, ...
So yes, I have listened to top range Sigma Delta's.

Our current SEN / CEN protos run on an AD1865. Many of R2Rs are no longer available. Very difficult to manufacture.
PCM1704 is expensive. If you do not want to over-sample (we do OS), then PCM56 is still affordable.

The cost of the DAC in the total cost of a built is less << 10%, and it is SQ deciding.
So I do not save money on them.


Just my personal choice,
Patrick

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[EUVL]

Someone mentioned that SEN / CEN is still with a cap, even though I explained in the article why it is unimportant here compared to ZEN or D1.
And he mentioned that most discrete IVs for ES9018 also have a cap.

If you really want to have no cap at the expensive of complication and higher distortion, I shall publish my folded cascode IV in due course (earliest October). That has 8 JFETs for 1 single ended channel, including one for a DC servo. here is an earlier proto in SMD

Zen I/V Converter

The one I posted at the beginning of the ZEN IV thread based on JC's BT is a good starting point.

Zen I/V Converter


Patrick

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[Calvin]

Hi,

what Cap are You talking about?

jauu
Calvin