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Building UCD 250LP input buffer
Building UCD 250LP input buffer
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Old 7th June 2018, 10:18 PM   #11
kjb is offline kjb  Sweden
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Thanks rmaudio!
Perhaps the boards are good enough by now, I will check them again for errors before ordering.
Any more suggestions of improvements are off course welcome!

Anyone want the cad files give me a PM.

Next step would be building a pcb for the Ucd400oem. (If no one are willing to share a design
However It should be quite easy to modify this board to use another pin-header to fit the Ucd400oem.

I have also thought about just replacing the op amp on the Ucd400oem with a LM4562 to improve the sound a bit. I'm not sure if Its a good idea thought. Hypex probably didn't design the decoupling the way they should have if they had chosen the lm4562 as the internal input buffer op amp from the beginning.
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Old 7th September 2018, 01:41 PM   #12
kjb is offline kjb  Sweden
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So I built the boards. Both for Ucd250 and Ucd400OEM. They turned out nice (can post pictures later) but I do have a problem with noise/hiss, especially coming from the Ucd250lp. They are fed with +-15V from a super regulator (ssr03). Its quite annoying, can't use them as long as thy is this noisy.
Any thoughts? Have I done a bad layout in some way?
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Old 7th September 2018, 08:24 PM   #13
Project16 is offline Project16  France
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Quote:
Originally Posted by kjb View Post
So I built the boards. Both for Ucd250 and Ucd400OEM. They turned out nice (can post pictures later) but I do have a problem with noise/hiss, especially coming from the Ucd250lp. They are fed with +-15V from a super regulator (ssr03). Its quite annoying, can't use them as long as thy is this noisy.
Any thoughts? Have I done a bad layout in some way?
In my opinion connecting all the GND (inputs, power supply and outputs) on a ground plane is a bad thing and I think a ground loop is created.
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Old 7th September 2018, 08:52 PM   #14
Nisbeth is online now Nisbeth  Denmark
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Building UCD 250LP input buffer
Disagree. If your external wiring is correct then a single groundplane in an all-analogue circuit shouldn't create a problem**

**possible exceptions: mixed-mode analogue/digital boards and boards such as power amps with both high and low currents on the same board (here, everything is line-level)
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Old 8th September 2018, 07:23 AM   #15
kjb is offline kjb  Sweden
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Quote:
Originally Posted by Project16 View Post
In my opinion connecting all the GND (inputs, power supply and outputs) on a ground plane is a bad thing and I think a ground loop is created.
Does anybody have a photo or knowledge of hypex own input boards. How did they do it.
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Old 8th September 2018, 10:08 AM   #16
Project16 is offline Project16  France
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No, I do not have this.
One thing is certain is that I already did a preamplifier line with a ground plane where all the GNDs were connected and I had a big buzz, the problem was solved once the components disconnected from the ground plane and brought back to the mass well separately.
Maybe it's not normal or a coincidence but I already had this problem and now apart in the digital pcb all audio with a ground plan will gnd well separated.
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Old 8th September 2018, 08:40 PM   #17
kjb is offline kjb  Sweden
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Quote:
Originally Posted by Nisbeth View Post
Disagree. If your external wiring is correct then a single groundplane in an all-analogue circuit shouldn't create a problem**

**possible exceptions: mixed-mode analogue/digital boards and boards such as power amps with both high and low currents on the same board (here, everything is line-level)
I have the signal connected to rca, shield 100ohm/100nF to ground as described in the nc400 datasheet, possibly there could be improvements here, the wiring probably isn't optimal.
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Old 11th January 2019, 12:54 PM   #18
JMSC is offline JMSC
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Hi, did you found the problem? Are you building the amp with mains safety gnd connected to chassis?

I'm building 5 channel amp from UcD400OEM modules.
I'm planning to make custom input buffer boards as an upgrade later and would be interested (and wery grateful) if you have kicad files for those.

Last edited by JMSC; 11th January 2019 at 12:54 PM. Reason: typos
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Old 23rd January 2019, 07:03 PM   #19
kjb is offline kjb  Sweden
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JMSC you got a PM


Quote:
Originally Posted by JMSC View Post
Hi, did you found the problem? Are you building the amp with mains safety gnd connected to chassis?

I'm building 5 channel amp from UcD400OEM modules.
I'm planning to make custom input buffer boards as an upgrade later and would be interested (and wery grateful) if you have kicad files for those.
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Old 31st January 2019, 01:08 AM   #20
enricofiocco is offline enricofiocco  France
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Hey Joel, nice work!
I'm also up to building a UCD400OEM amp, and I'd love to see your cad files ;-)
thanks a lot, regards
Enrico
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