O-Noorus D1 - TPA3255 PFFB Stereo Amplifier with the Analyser-unreliable

[thin bLue]

LTNS
1st of all,

Unbal Internal loop back

Bal internal loopback

Bal Exnternal loopback

Consistent DC artefacts with the results.
Our deer Analyser lost all of reliability

Just Cry Quuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu


Anyways, It'll will soon be figured out.
So, tests below do not have Any-Of-Reliability.

Our deer member 유샤(pronounced as yu-sha) of DCinside speakers gallery lent it for free.

Due to reliability issues with the instrument, only minimal testing has been done. I hope to make more details once the issue is resolved.


Before starting the test, channel 1 (left channel) was not working, so I had to recheck the entire measurement environment. (Just Cry Again Quuuuuu)
Turning the amplifier off and on again solved the problem.

4 Ohms 5 W
10Hz<, 22.4k
SINAD @ Vol 50, BP mode

4 Ohms 5 W
10Hz<, 90k
Gain @ Vol 50, BP mode

4 Ohms 5 W
10Hz<, 90k (
FR @ Vol 50, BP mode

4 Ohms 5 W
10Hz<, 90k
Impulse @ Vol 50, BP mode

4 Ohms 5 W
10Hz<, 90k
GD @ Vol 50, BP mode, lower frequency delay may be caused by HP filter.

4 Ohms 5 W
10Hz<, 90k
Multitone @ Vol 50, BP mode








Spec sheet shows, the Volume range 0 - 80.
As same as the spec, display stops at 80. But the knob still turns bit more and actual gain climbs up too.

Vol. 50, Gain about 12.5 dB
@ BP mode

Vol. 80, Gain about 23.2 dB
@ BP mode

Vol. Max(displayed as 80), Gain about 26.1 dB
@ BP mode

This is all for today.

The whole world is full of extreme uncertainty.
And I am just constantly lying in bed, wrapping myself in a blanket doing nothing. (Very comfortable)
Just Cry Quuuuuuuuuuuu

 

[LIΟN]

This is a review that brings tears to my eyes. Thank you for your dedication.

 

[thin bLue]

This is a review that brings tears to my eyes. Thank you for your dedication.

View attachment 384754

Who cries receives good luck.
Just Cry Quuuuuu

 

[yuusha]

I am in tears looking at the measurements of this amplifier. The FR suggests that the pffb circuit is doing its job, but the very high distortion is a sorrow.
Furthermore, the strange behavior of the volume knob makes the hardware seem unreliable.

 

[thin bLue]

View attachment 384758
I am in tears looking at the measurements of this amplifier. The FR suggests that the pffb circuit is doing its job, but the very high distortion is a sorrow.
Furthermore, the strange behavior of the volume knob makes the hardware seem unreliable.

The manufacturer's choice is somewhat understandable, as it would have been difficult to guarantee performance in the 80+ range, and most users would dislike recommendations that 'we only guarantee performance only up to 80' when the numbers are displayed up to 100.

However, upon initial turn-on, it was somewhat difficult to understand why only one channel did not work. I would probably not call this amp very reliable.

But, there are a lot of interesting features! So it'll be fun to explore them in the future, but there are more tests to do than I thought, so I'll have to figure out how to streamline them. (crying)

 

[yuusha]

The manufacturer's choice is somewhat understandable, as it would have been difficult to guarantee performance in the 80+ range, and most users would dislike recommendations that 'we only guarantee performance only up to 80' when the numbers are displayed up to 100.

However, upon initial turn-on, it was somewhat difficult to understand why only one channel did not work. I would probably not call this amp very reliable.

But, there are a lot of interesting features! So it'll be fun to explore them in the future, but there are more tests to do than I thought, so I'll have to figure out how to streamline them. (crying)

A normal person would think that when the numbers stop running, the amplification stops, but I think that amplifying regardless of visualization risks "frying" my speakers.
One other ASR user (https://audiosciencereview.com/foru...rol-with-bypass-and-remote.53251/post-1976039) with this deer amplifier also mentioned an issue with no output on one channel. The manufacturer said they've updated it, but I'm a bit curious that the issue still occurs.

 

[thin bLue]

A normal person would think that when the numbers stop running, the amplification stops, but I think that amplifying regardless of visualization risks "frying" my speakers.
One other ASR user (https://audiosciencereview.com/foru...rol-with-bypass-and-remote.53251/post-1976039) with this deer amplifier also mentioned an issue with no output on one channel. The manufacturer said they've updated it, but I'm a bit curious that the issue still occurs.

Let's f/u.
I think there will probably be some updates very soon!

 

[UAN]

Judging by the graph of the output signal level versus frequency, your amplifier is damaged.

Probably, the PFFB feedback is disabled.

In it.In my D1 amplifier, the frequency response is linear up to 20 kHz. Then a smooth decline after a frequency of 20 kHz.

This is with a load resistance of 4 Ohms.

If the load resistance is 8 Ohms, then the amplitude increases at a frequency of 30 kHz to 1 dB and a smooth decline after 40 kHz.

 

[yuusha]

Judging by the graph of the output signal level versus frequency, your amplifier is damaged.

Probably, the PFFB feedback is disabled.

In it.In my D1 amplifier, the frequency response is linear up to 20 kHz. Then a smooth decline after a frequency of 20 kHz.

This is with a load resistance of 4 Ohms.

If the load resistance is 8 Ohms, then the amplitude increases at a frequency of 30 kHz to 1 dB and a smooth decline after 40 kHz.

Thanks for your comments.
To summarize what you're saying, with a boost of 0.8dB at 20k, that the feedback loop is damaged? I'm wondering if your D1 amp shows the same FR as the two amps I attached the images about?
Could you please share your measurements on ASR? I'm very curious.

 

[UAN]

Thanks for your comments.
To summarize what you're saying, with a boost of 0.8dB at 20k, that the feedback loop is damaged? I'm wondering if your D1 amp shows the same FR as the two amps I attached the images about?
Could you please share your measurements on ASR? I'm very curious.

The frequency response of my D1 is very close to the frequency response of the A70. Only at a frequency of about 30 kHz and a load of 8 Ohms the gain is 1 dB higher.