The new Nonoz II DAC page !!!

[fedde]

Hi guys!

The Nonoz II DAC page is finished. This is my newest non-oversampling project. It's quite affordable and easy to build...

So have a look at:
http://home.student.utwente.nl/f.s.b...io/nonoz2.html

Have fun!

Fedde

[king30]

Fedde,
Some questions on the T4-6T Transformer.

1. Could you post a schematic on how it was applied in your application. I looked at Marc's page but your DAC's at the digital input seem a little different.

2. Whats the purpose of the transformer. Along with cleaning the signal, does it strengthen the signal it at all.

3. Can it be purchased in small quantities 1-2. The quote on the mini-circuits page is for 10-49.

Thanks...Lee

[jean-paul]

The answer on question 2 can be found here:

http://members.brabant.chello.nl/~m....tml/inprec.htm

The schematic on Fedde page is without transformer. Probably Fedde forgot to draw it because the PCB with the transformer is my design . I included the transformer for several reasons as found on this forum and on Marc Heijligers page. Just do a search on digital transformer and you'll find all details and reasons for using them.

The DAC really performs better with a good transformer. Problem is to find a good one. This step-up one can be obtained from Guido Tent ( the man from the XO clocks, he is a member of this forum too ).

I also made some DAC's with Lundahl LL1566 which is not as bad as many say on this forum. Well, it is better than no transformer at all

[Elso Kwak]

Originally posted by jean-paul
The answer on question 2 can be found here:

http://members.brabant.chello.nl/~m....tml/inprec.htm

The schematic on Fedde page is without transformer. Probably Fedde forgot to draw it because the PCB with the transformer is my design . I included the transformer for several reasons as found on this forum and on Marc Heijligers page. Just do a search on digital transformer and you'll find all details and reasons for using them.

The DAC really performs better with a good transformer. Problem is to find a good one. This one can be obtained from Guido Tent ( the man from the XO clocks, he is a member of this forum too ).

I also made some DAC's with Lundahl LL1566 which is not as bad as many say on this forum. Well, it is better than no transformer at all

Hi jean-Paul,
If I remember correctly Fred told us the transformer should be in the transport and the 74HCU04/ 74HC86 at the DAC end of the transmission line preventing the CS8412 spitting back into the cable. Of course my interface with AD8561 would also work.

[king30]

I am using Scott dixons DAC. Could I just lift the connections to RXP and RXN and insert the transformer or does it require additional modifications? my digital input looks the same as feddes below...Lee

[king30]

or maybe something along the lines of this setup.
http://beggingdogrecords.tripod.com/DAC.html

[jean-paul]

Originally posted by Elso Kwak

Hi jean-Paul,
If I remember correctly Fred told us the transformer should be in the transport and the 74HCU04/ 74HC86 at the DAC end of the transmission line preventing the CS8412 spitting back into the cable. Of course my interface with AD8561 would also work.

Mmm, I don't know what should be done by whom but sometimes it can be refreshing to build something and find out yourself. Which I did with some types of transformers and I found out this typical transformer is implemented very well in the Heijligers DAC. Maybe your interface works good too but it is more complex and from what I read things can go wrong too. I like this simple interface because it is simple AND better than coupling like the datasheet says. No more, no less. I want to add that I prefer transformers at both sides of the line.

Lee, the transformer described can not be used in the way your link shows. Just look at the Heijligers DAC's schematic for optimal results. I used the Lundahl LL1566 ( which is a 1:1 transformer unlike the Minicircuits type ) directly on the RXP and RXN pins with a 75 Ohm resistor at the secondary windings. I only can advise you to try out yourself. Never forget to use a cap in the primary of the used transformer and keep wiring short.

[Pedja]

Hello Fedde,

Looks fine.

One notice though.

I checked that 3.3nF value of shunt caps at the output and found their value too tall if used with 1.5k resistors. They roll-off already at 20kHz some 1.5dB (30degs phase shift). Add natural non-os’s 3.5dB roll-off and you’re at 5dB. Take note on this if it is not what you intended. I still can hear 1dB roll-off at 20kHz and I think you’re younger than I

Pedja

[jean-paul]

You were too fast for me Pedja as I noticed the same

3.3 nF is OK with the 1 k resistors in a 5V supply setup. Despite all positive comments about 6V and even 8V supplies I quit experiments with this some time ago as results were disappointing with 8V ( and 1k69 for I/V ) with my TDA's. It distorted clearly with bass signals. Scott pointed out to me that not all TDA1543 can handle 8V. He handpicks the ones he uses in his DAC's. Respect for doing so !

Since then I only used 5V, 3 x 1 k and no caps in the first DAC and 3.3 nF in the current ones. Only this evening I soldered a 6V regulator in to check again if it is better or not. I recalculated the resistors for I/V and Vref to make things according the datasheet as pointed out by Rbroer in this thread:

it dosnt work!!!(TDA1543)

Since my stock of Styroflex is running out I used leftover 2.2 nF caps for filtering. Did not have the opportunity to listen to it unfortunately as other things had to be done.

[king30]

Jean-Paul,
Do you mean something like this...Thanks Lee