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Build Thread - A New Take on the Classic Pass Labs D1 with an ESS Dac
Build Thread - A New Take on the Classic Pass Labs D1 with an ESS Dac
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Old 16th October 2017, 10:02 PM   #691
BrianDonegan is offline BrianDonegan  United States
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Build Thread - A New Take on the Classic Pass Labs D1 with an ESS Dac
Quote:
The current increase from the 9018 to the 9038 is 4x, not 8x, right?
Yes, 4x. Posting in haste at work ��
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Old 16th October 2017, 10:14 PM   #692
Sabrosa is offline Sabrosa  United States
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Phew. Was hoping I hadn't missed something since I don't yet have a 9038 board in front of me to test directly.
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Old 6th December 2017, 02:12 PM   #693
Malefoda is offline Malefoda  France
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Anyone knows the Zout of the NTD1 (V4)? Or which preamp/amp Zin highest/lower values it can drive ?
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Old 10th December 2017, 02:52 PM   #694
Malefoda is offline Malefoda  France
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Quote:
Originally Posted by BrianDonegan View Post
I am not sure what the specific change will be, but you will need to adjust to accommodate the higher (8x) current output.
That holds as true that BIIIsePro ES9028 is drop-in replacement for a BII/BIIIse? Tempting!
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Old 13th February 2018, 08:21 AM   #695
JoeyDD is offline JoeyDD  Canada
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Build Thread - A New Take on the Classic Pass Labs D1 with an ESS Dac
Default MOSFET matching results

Hello,

I've been slowly gathering the required bits and pieces to build the NTD1 and I've finally finished matching the mosfets.
I have the V4 PCB with all SMD components so the mosfets are those specified on the newer BOM: the FDB52N20. I only ordered 10 of them for now to test the matching process. I used the matching instructions Owen posted, with a lab power supply set at 45V and a signal generator at 1kHz. The D2Pak format of the mosfets was a little challenging to work with (tried to avoid soldering/desoldering each one while still having it on a heatsink).
The results show a smaller transconductance than what was measured for the FQA32N20, so I'm wondering if my measured values look ok?

Thanks
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Old 14th February 2018, 04:15 PM   #696
JoeyDD is offline JoeyDD  Canada
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Build Thread - A New Take on the Classic Pass Labs D1 with an ESS Dac
I just noticed that I didn't adjust the testing rig to account for the decrease in supply voltage from 45V to 38V for V4 of the NTD1.
Given that we want about 100mA of idle current, I would adjust VR1 to 18 VDC (Vds of 20V) and keep everything else in the rig the same for the measurements of Vgs and matching for Vds?
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Old 3rd March 2018, 11:17 PM   #697
JoeyDD is offline JoeyDD  Canada
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Build Thread - A New Take on the Classic Pass Labs D1 with an ESS Dac
To follow up on my question, for anyone else that may be wondering the same thing, I can confirm that Vds should be 20V and the voltage should be adjusted to obtain 18V across R1 when matching mosfets for V4 of the NTD1. Those were the exact measures I got after finishing the NTD1 and measuring everything on the board.

These are the values I got with the appropriate settings for only 10 FDB52N20. I used # pairs 6-7 and 5-9 for my NTD1, so would have #1-2-3-8 that could be used for another V4 NTD1 if anyone needs them and doesn't feel like matching mosfets.
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Old 21st March 2018, 04:36 AM   #698
Mull3t is offline Mull3t  United States
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Didn't see an answer to Malefoda's question.

Is it possible to use the newer BIIIsePro ES9028 with the v3 version of the NTD1 as a drop in replacement for the BIIIse?
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Old 21st March 2018, 11:04 AM   #699
BrianDonegan is offline BrianDonegan  United States
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Build Thread - A New Take on the Classic Pass Labs D1 with an ESS Dac
Quote:
Originally Posted by Mull3t View Post
Didn't see an answer to Malefoda's question.

Is it possible to use the newer BIIIsePro ES9028 with the v3 version of the NTD1 as a drop in replacement for the BIIIse?
The output levels are the same, so it should drop right in.
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Old 21st March 2018, 11:14 AM   #700
Malefoda is offline Malefoda  France
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Yep talked of that offline once and it's as simple as Brian said. Just need the money to buy the BIII ES9028 and to find out if it is worth as many reviews feature also a new output stage and new Tridents (no review with just the BIIIpro board and same I/V).
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