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Old 21st December 2013, 08:18 PM   #51
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I think that the new discrete differential no feedback output stage is able to do "fly" every amplifier. The signal tranformer is a good choice but you have to check if the input impedance of the amp dampens the risonance of the tranformer ( +3-6dB ). The effects of high frequency can be perceived as a loss of bass.
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Old 22nd December 2013, 02:14 PM   #52
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Quote:
Originally Posted by claudio52 View Post
The signal transformer is a good choice but you have to check if the input impedance of the amp dampens the resonance of the transformer
So if transformer and amp don't play well together ... the solution is a buffer in between?
Would a more basic buffer be OK, other than the B1 (or DCB1) that Erlend used ?
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Old 22nd December 2013, 06:16 PM   #53
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The problem is the impedance seen from the secondary of the transformer. If too low, the peak of the resonance (positive peak followed by a dip negative )is not damped. The buffer can not delete it. To linearize the frequency response there two ways.
1) Close the secondary with a low resistance. Unfortunately these loads load too the stage connected to the primary. With my tranformer have a linear response with 20K. The impedance reflected to the primary is only 8.9K. Perhaps they are too low for ES9018.
2) Insert an R-C network on the secondary ( R1-2, C1-2 ). What will, however, its effect on the sound?
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Old 23rd December 2013, 11:35 AM   #54
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Thanks claudio52,
Looking at Quanghao's most recent schematic attached to the first post -
http://www.diyaudio.com/forums/attac...ll1684-dac.jpg
I see a 3nF cap plus 1K resistor across the outputs of the secondaries.
So this is an RC network, which should suitably dampen the transformer's resonance?
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Old 23rd December 2013, 12:22 PM   #55
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It is precisely that
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Old 23rd December 2013, 12:40 PM   #56
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Thanks.
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Old 1st January 2014, 07:12 PM   #57
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1. NicMac: 1 set (possibly also the transformers)
2. palmito: 1 set
3. Misterwolf: 1 set = 1(25$)+2(2$)+4(2$)+6(7$)+shipping(10$) = 46$
4. audiodesign: 1 set
5. danielkol: 2 set
6. Mas Penk: 1 Complete kit... Shipping together with DAC kit
7. flowerpot: 1 set
8. Stenachio: 1 set, including all parts (if possible), shipped with DAC kit
9. Sandor: 1 complete set with LL1684, shipping with DAC kit
10. Rowli: 1 complete set with LL1684
11. nkdk: 2set. pcb
12. Nick F: Complete kit (items 1-8) ship w/DAC?
13. hordmop: 2 set = 1(50$)+2(4$)+3(13$)+4(4$)+5(10$)+6(14$)+7(76$)+shi p ping(20$) =191$
14. msaywitz: Complete Kit (items 1-8), shipped with DAC kit.
15. MattMax: Complete kit, including LL1684 transformers + shipping.
16. necplusultra: 1 set (possibly also the transformers)
17. flocchini: 1 complete set with transformers
18. gjorgji: Complete kit, including LL1684 transformers + shipping
19. myfavoritething: 1 complete kit with LL1684 +shipping, + Amareno usb module + LNV and the caps to modify coax and AES output
20. meintan: 1XItem1($25)+1XItem5($5) + 2XItem6($14) + Shipping($10). May I have a dac shield please. Have not received mine.
21. linuxfan: 1 kit, WITHOUT LL1684 - items 1-7 (plus shipping)
22. Jinkslynx: Item 1-6+8, have some M-caps on hand. Sum 367,5
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Old 10th January 2014, 05:12 PM   #58
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Quanghao : When do we start to pay for this GB? I expect the V/I can be shipped together with the DAC...
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Old 10th January 2014, 10:04 PM   #59
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Quote:
Originally Posted by Mas Penk View Post
Quanghao : When do we start to pay for this GB? I expect the V/I can be shipped together with the DAC...
yes i can!
The PCB i make with the DAC V2!
thanks
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Group buy DAC-END R (ES9018) full assembled board
update 06/14/2013 :http://www.audiodesignguide.com/DAC32/index2.html
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Old 12th January 2014, 03:19 PM   #60
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Quanghao : I sent you $300 for DP of the V/I.
Please let me know when you have completed all item (GB DAC + V/I)
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