O-Noorus D4 Pro - TPA3255 PFFB Balanced Amplifier with DAC, HDMI ARC/Sub-Out/LPF/HPF

[MidnightCarouselRider]

I ordered a d4 pro today. I also ordered a brzhifi tpa3255 subwoofer amplifier for a old velodyne I turned into a passive. I will be using it in my bedroom system and replacing a trusty ayimia a07

 

[Guddu]

Something I want to share quickly on D4 Pro

I recently got my hands on D4 Pro and it is a feature rich refined amplifier... rather fantastic.

Highlights for me:

Slim profile, well build and does not heat up
All possible digital inputs available
HDMI ARC Operation
- No HDMI ARC issues, works perfectly
- Turns ON/OFF with TV on HDMI ARC
- When turned ON by TV with HDMI ARC, it lowers the volume to "number 10" which prevents any accidental loud volume
- After turning ON with HDMI ARC (with volume 10), volume goes to previous volume position when volume button used on amplifier remote or TV remove
- Volume changes with TV volume & TV remote, volume number/position reflects on the display on amplifier
- Note that it does not have motorized potentiometer, so knob doesn't move but display shows the volume change

Tone Control and ByPass mode
Dedicated HPF & LPF, subwoofer out

Subjectively its as good as any other well measured amplifier, to me.

D4 Pro is probably the best bang for buck in my opinion.

@Alexander Lin Congrats for a very well done product

 

[Guddu]

Sorry but if you mean the D4 Pro amp, the topic of this thread

Why are you talking about something called "D04 Pro" ?

Thanks, corrected

 

[whazzup]

Just gotten my grubby hands on the D4 Pro, along with 2 adapters 36V10A and 48V10A. The heat when hooked up to the 48V is substantial, casing bottom too hot to hold comfortably. With 36V it's just a few degrees above ambient. Only measuring the bottom pcb, not the chips directly. Can't really tell if there's a difference in volume, will need to measure to say for sure.

There's also a weird issue, where if I use the 36V adapter, the moment I connect USB or RCA in (connected to my pc), power trips, even when the main wall power socket is turned off (every equipment powered down including pc, dac and amp). Does not happen with the 48V adapter. In order to use the amp with the 36V adapter, I have to use the DX1 ii dac > optical out to D4 Pro.

Have not updated any firmware yet, plus my adapters are not from O-Noorus, so at the moment I can only say the signs point to the 36V adapter having some issue.

With 48V10A power supply, no external fan, idle temperature of bottom pcb through ventilation slot: ~54°C

With 48V10A power supply, external fan running, idle temperature of bottom pcb through ventilation slot: ~45°C

With 36V10A power supply, no external fan, idle temperature of bottom pcb through ventilation slot: ~37°C

The power adapters (3rd party, not O-noorus product)

 

[Alexander Lin]

The casings of the D4II and D4 PRO directly contact the TPA3255 chip,
rather than indirectly through a heatsink. Therefore, heat is dissipated directly onto the casing.
The area between the two screws at the bottom is directly below the TPA3255, where the temperature is highest.

 

[whazzup]

The casings of the D4II and D4 PRO directly contact the TPA3255 chip,
rather than indirectly through a heatsink. Therefore, heat is dissipated directly onto the casing.
The area between the two screws at the bottom is directly below the TPA3255, where the temperature is highest.View attachment 552461

Thanks, great to hear that. Meaning any bottom fan will be targeting the chip directly. I think 30-36V is a good option for those who may be concerned about heat but do not want active cooling (when running with the 48V).

Can I also ask, is there a rationale for not having more slots in the casing? Reduced dust buildup? Fabrication cost? Asethetics?

 

[Alexander Lin]

Thanks, great to hear that. Meaning any bottom fan will be targeting the chip directly. I think 30-36V is a good option for those who may be concerned about heat but do not want active cooling (when running with the 48V).

Can I also ask, is there a rationale for not having more slots in the casing? Reduced dust buildup? Fabrication cost? Asethetics?

Ventilation slots can be added to the bottom, and openings can be made at the top to increase the pathways for dust to enter.

 

[whazzup]

How the various knobs on the D4 Pro change the measured frequency response. Using a Monitor Audio Bronze 1 speaker, close miked. It was crying for help at max Bass / Treble settings

Bass / Mid / Treble adjustment effects on Speakers

Bass adjustment effects on Subwoofer

High Pass Filters (mic probably too close to speaker front to minimize reflections so didn't quite capture No HPF - HPF 60 difference)

and Low Pass Filters (on Subwoofer)

 

[Nigel]

I just received my O-Noorus D4 Pro and these are my initial impressions.

I can't really comment on the audio quality because I really don't know what I'm listening for, but everything sounds good to me.

However, from UX perspective there are a few significant (but in some ways easy to fix) issues. Probably just a little bit more QC and a few dollars more on components.

First, the neutral position for the tone controls are not all straight up. This just looks bad.

The tone knobs scrape when you turn them fully up or down. I pulled one knob off and the potentiometer turns smoothly, so I believe it is the knob scraping the case.

The volume push-to-select function is quite clunky. I've felt some really nice versions of this, but this feels cheap.

Also, there is no manual for this device, not that it is that complicated, but it is nice to have an authorative summary of the specs, compatibility, etc.

I hope the knob QC issues can be resolved for the remaining stock, because little things like that can really detract from what is otherwise a quality product.

 

[whazzup]

I just received my O-Noorus D4 Pro and these are my initial impressions.

I can't really comment on the audio quality because I really don't know what I'm listening for, but everything sounds good to me.

However, from UX perspective there are a few significant (but in some ways easy to fix) issues. Probably just a little bit more QC and a few dollars more on components.

First, the neutral position for the tone controls are not all straight up. This just looks bad.

View attachment 558463

The tone knobs scrape when you turn them fully up or down. I pulled one knob off and the potentiometer turns smoothly, so I believe it is the knob scraping the case.

The volume push-to-select function is quite clunky. I've felt some really nice versions of this, but this feels cheap.

Also, there is no manual for this device, not that it is that complicated, but it is nice to have an authorative summary of the specs, compatibility, etc.

I hope the knob QC issues can be resolved for the remaining stock, because little things like that can really detract from what is otherwise a quality product.

Yes, the tone knobs on my unit have the same issue. But it's a minor annoyance. My guess is whoever they contracted the knob-making to have less than ideal QC requirements in place.

 

[oldloder]

I just received my O-Noorus D4 Pro and these are my initial impressions.

I can't really comment on the audio quality because I really don't know what I'm listening for, but everything sounds good to me.

However, from UX perspective there are a few significant (but in some ways easy to fix) issues. Probably just a little bit more QC and a few dollars more on components.

First, the neutral position for the tone controls are not all straight up. This just looks bad.

View attachment 558463

The tone knobs scrape when you turn them fully up or down. I pulled one knob off and the potentiometer turns smoothly, so I believe it is the knob scraping the case.

The volume push-to-select function is quite clunky. I've felt some really nice versions of this, but this feels cheap.

Also, there is no manual for this device, not that it is that complicated, but it is nice to have an authorative summary of the specs, compatibility, etc.

I hope the knob QC issues can be resolved for the remaining stock, because little things like that can really detract from what is otherwise a quality

I only had a short time so far to begin testing mine out but I've found much the same and agree that it seems to be working properly and sounds good and hope that these small QC issues (and no major ones appear) will be resolved for the same reason as I think this unit with the adjustable HP/LP filters essentially make this a desktop small user friendly integrated amp to replace the big menu driven receivers that intimidate so many people I try to help to better music at home.

I always like (and miss) a manual for this as well. The knob scraping and misalignment are also present on mine, but I was able to pull the knobs out with my fingers enough to stop the problem. One knob is slightly misaligned but I appreciate the indents more than that bothers me.

If this proves a good performer over time at this price point I'd think this could become very popular.