NEW O-NOORUS D4 (TPA3255 PFFB / HDMI ARC / ES9023P)

[mcdn]

Detailed review is up at https://www.audiosciencereview.com/...s/o-noorus-d4-budget-stereo-amp-review.61917/

Assuming your sources can provide the usual 2Vrms output, there's no reason to have the D4 at more than 50% (12o'clock) volume setting.

 

[sabih]

Hello, @Alexander Lin

I want to convert my D4 to direct power amp without volume control i.e [bypass potentiometer].
Please can you ask your engineers and guide me how it can be done.
Thanks.

 

[Alexander Lin]

Hello, @Alexander Lin

I want to convert my D4 to direct power amp without volume control i.e [bypass potentiometer].
Please can you ask your engineers and guide me how it can be done.
Thanks.

You turn the potentiometer to maximum.

 

[sabih]

My review of the amplifier O-noorus D4 PFFB

View attachment 432617

Received a parcel from @meta1984
Within 30 minutes, using simple tools, I fixed the problem with the noise in the speakers. The problem was in the incorrect assembly of the cooling system, the capacitor legs were close to the radiator plate, I shortened them with nippers and everything worked.

View attachment 432618

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Then I made several changes:
1. Replaced the operational amplifiers. Instead of opa1642a, I installed NE5532, this reduced the noise level and increased the SINAD to 90.3 dB

2. Changed 4 capacitors around the operational amplifiers, instead of 200pF, I installed 100pF, this made the frequency response almost straight.

Sine Wave 1kHz SINAD 90.3dB at load 4ohm 9W
View attachment 432624


Maximum power 63.5W at load 8ohm and THD 1%
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RMAA measurement reportView attachment 432626
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I recorded the sound of the amplifier via Bluetooth, a flash card, a coaxial port, I will publish a video review on YouTube a little later.

Why you replaces 200pf capacitor with 100pf.
Please explain

 

[ICIETDIYEUR]

Hi sabih

The answer is in his text -> '...Changed 4 capacitors around the operational amplifiers, instead of 200pF, I installed 100pF, this made the frequency response almost straight...'

But no before/after curves were presented to demonstrate this: neither with a 4 Ohm load, nor with an 8 Ohm load

Have a nice day