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Old 25th April 2009, 06:58 PM   #391
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Quote:
Does this transformer and/or the circuit quoted work well for 192 Khz?
Uuups, maybe not? This is a input circuit from a 44.1kHz DAC.

Franz

BTW:

Digitec owners: just connect the primary with two 10 Ohm resistors to the DAC, and they'll be singing!
And when you want to filter, just add a 470nF cap in parallel to the primaries (but I dont like it filtered).
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Old 25th April 2009, 08:04 PM   #392
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Thanks Franz. Based on my learning from this thread, I see that it has decoupling caps too. That is useful to know because last night I finally went for the upsampling version of the DAC board (from Ebay seller gigawork), which does not have the input transformer.

Those GA80080 Tamura's were also winking at me, so I have a pair of those coming as well. I guess it is time to plug in my soldering iron now if it needs to get to 750C!

Thanks to Kevin & Franz for their responses and for everyone elses contributions on this thread which have led me to this point. I will report in as soon as I hear music!


Cheers

Oli
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Old 25th April 2009, 08:04 PM   #393
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udovdh - there is a datasheet for the DV709 towards the bottom of this page...

DV709 Datasheet

I hope it helps (but I am not sure how to decipher it!).
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Old 26th April 2009, 12:01 PM   #394
johnm is offline johnm  United Kingdom
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Quote:
Originally posted by Franz Gysi

Digitec owners: just connect the primary with two 10 Ohm resistors to the DAC, and they'll be singing!
And when you want to filter, just add a 470nF cap in parallel to the primaries (but I dont like it filtered).

Hi Franz.

With the above I take it you are now not using loading resistors on the secondaries? I'm currently using 10K here but really can't here much - if any - difference between that and no load resistors. I'll try a higher value later today.

In the above mod you mention, are you using two 10 ohm resistors per transformer? I.e. 10 ohm from the transformer to the L- and L+

Cheers!

- John
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Old 26th April 2009, 04:05 PM   #395
udovdh is offline udovdh  Netherlands
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Quote:
Originally posted by hoverdonkey
udovdh - there is a datasheet for the DV709 towards the bottom of this page...

DV709 Datasheet

I hope it helps (but I am not sure how to decipher it!).
They mention 7 Mbps max, 192 Khz 24 bits is about 3.8 Mbit/s so the DV709 should do well!
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Old 26th April 2009, 04:10 PM   #396
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Quote:
With the above I take it you are now not using loading resistors on the secondaries? I'm currently using 10K here but really can't here much - if any - difference between that and no load resistors. I'll try a higher value later today.
John

I think the secondary load does only very marginal difference.
Later, I will measure on the scope if I see ringing and will then fiddle out a RC combination. I will post it here.

Quote:
In the above mod you mention, are you using two 10 ohm resistors per transformer? I.e. 10 ohm from the transformer to the L- and L+
Exactly, two resistors per transformer. On each side of the primary one connecting to L- and the other to L+.

Then you can add 0.33uF in parallel to the primary as lowpass filter.

This combination, I like very much!

Franz
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Old 26th April 2009, 04:21 PM   #397
johnm is offline johnm  United Kingdom
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Many thanks Franz - look forward to hearing about your results with the scope too.

This DAC really is something special with the transformers isn't it. Surprisingly, I've also found that the optical input seems to be every bit as good as the coaxial one, unless its my cloth ears of course! Using a USB Trends UD10.1 and an optical cable, playing lossless files via Foobar2000 with the WASAPI plug in for Windows Vista, I'm in audio nirvana So a BIG thanks for all your help thus far Franz, and indeed everyone else on here who's helped/contributed in some way.

- John
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Old 26th April 2009, 05:35 PM   #398
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Actually I am building one of this little 707 DAC in a small italian Galaxy enclosure:

Click the image to open in full size.

Including psu and Digitec output trannies.

Franz
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Old 27th April 2009, 08:40 AM   #399
anbello is offline anbello  Italy
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Quote:
Originally posted by udovdh

They mention 7 Mbps max, 192 Khz 24 bits is about 3.8 Mbit/s so the DV709 should do well!

I think 3.8Mb/s it's wrong, 192*24*2=9216 so about 9.2Mb/s.

Ciao
Andrea
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Old 27th April 2009, 03:32 PM   #400
udovdh is offline udovdh  Netherlands
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Quote:
Originally posted by anbello



I think 3.8Mb/s it's wrong, 192*24*2=9216 so about 9.2Mb/s.
Yes I forgot the 2nd channel...
But that makes 7.110 Mbps?
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