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Old 10th March 2003, 10:11 PM   #11
vuki is online now vuki  Croatia
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Hi Phil,

you can't drive it differentialy using just 74hcu04. You'll also need 74hc86 wired as diff. driver.
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Old 10th March 2003, 10:19 PM   #12
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Vuki,

I have found out that the 74hc86 is a quad 2-input exclusive-or gate. Please can you give me some help as to how to wire it to give the desired effect (i.e. differentially driving the CS 8412)?

Thanks
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Old 10th March 2003, 10:23 PM   #13
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Default Fred's Way/Circuit

Quote:
Originally posted by PhilW
Vuki,

I have found out that the 74hc86 is a quad 2-input exclusive-or gate. Please can you give me some help as to how to wire it to give the desired effect (i.e. differentially driving the CS 8412)?

Thanks
Hi Philw,
Just look here.
http://www.diyaudio.com/forums/showt...0851#post90851
And the Pass DAC D1 for the idea with the 74HC86.
/ not using SPDIF anymore.....
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Old 10th March 2003, 11:03 PM   #14
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Smile SPDIF Interface

Hi tiroth,
I received the following feedback from Mike:
"
I finally tried your AD8561 SPDIF interface (just the receiver part of the circuit) in my TDA1543 non-oversampling (NOS) DAC and it worked great. There was quite an improvement in sound quality over having the SPDIF input connected through two caps directly to the CS8412. The CS8412 connects to four TDA1543s. The interface also solved a digital lock problem I had with my TDA1543 NOS DAC. Before adding your AD8561 SPDIF interface, I almost always had to wait 15 to 30 minutes for the DAC to warm up before it would lock on to the digital out from my transport. I'm also using Wildmonkeysect's loopfilter on the CS8412. I guess Jocko was right about the CS8412's Schmitt-trigger input dumping noise back into the SPDIF cable.
THANKS for the help.
"

So I believe it can work.

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Old 11th March 2003, 09:51 AM   #15
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Unhappy Using 74hc86 to drive 8412 differentially

>Just look here.
>http://www.diyaudio.com/forums/show...90851#post90851
>And the Pass DAC D1 for the idea with the 74HC86.


I looked, but as far as I can see the Pass DAC D1 uses a transformer coupled into the 8412 by two capacitors. The 74hc86 in the diagram is used for something completely different.

I am still no further on with the 74hc86 - how do we wire it to drive differentially please?
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Old 11th March 2003, 11:47 AM   #16
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Cool Freds Interface

Hi Philw,
Attached what I think is the interface Fred meant.
You must use the 74HCU04 (Unbuffered).
It would be interesting to hear how it performs with 74VHCU04 and 74VHC86.
Elso/not using SPDIF interface anymore
/ Why am I doing this?
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File Type: gif f-interface-sm.gif (16.6 KB, 1517 views)
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Old 11th March 2003, 12:09 PM   #17
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When we are at it, i have a queation:

What kind of capacitor is best used in these digital transmissions.
Should i use poly, tantalum, ceramic or others for the 47nF?
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Old 11th March 2003, 12:22 PM   #18
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Why not use a decent 75 Ohm pulse transformer at the input of CS8412 ?
The results with a transformer are very good and it is a simple solution compared to the electronics I see in your schematic. I tried 2 real "digital" transformer-types and they offer a clear improvement over direct coupling. Apart from the quality of the transformer not much can go wrong.

The only problem is finding decent transformers, I know

Wombat, I did some experiments with capaitors at the input of the Crystal and filmtypes ( MKP, MKT etc ) are not beneficial in this application. Best results were with Kemet X5R ceramics.
I once tried a Wima 100 nF MKT and there was audible distortion introduced. I did not care for any measurements as I wanted to listen so I changed it immediately for a good ceramic cap and everything was OK again.

Not a scientific approach but very effective
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Old 11th March 2003, 12:49 PM   #19
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These are the ones I used with success.
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File Type: jpg ceramic1.jpg (51.0 KB, 1265 views)
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Old 11th March 2003, 01:32 PM   #20
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Default Pulsetransformer for SPDIF

Quote:
Originally posted by jean-paul
Why not use a decent 75 Ohm pulse transformer at the input of CS8412 ?
The results with a transformer are very good and it is a simple solution compared to the electronics I see in your schematic. I tried 2 real "digital" transformer-types and they offer a clear improvement over direct coupling. Apart from the quality of the transformer not much can go wrong.

The only problem is finding decent transformers, I know

Yah, Jean-Paul,
Why not share your knowledge of what you think is a decent pulse transformer?
Fred rolls his own but did not want to share his design.
I addition I can report that my interface at the DAC side with the AD8561 comparator also works very well with the JK-Acoustics transport.http://www.jkacoustics.nl/Ref%20CD-transport.htm
It is a Philips CDM12pro.
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