Nobsound TPA3255 Amplifier

[IowAudio]

I got this Nobsound TPA3255 off Amazon for $109. Its same thing as the BRZHiFi both based on the TPA3255 and a built in power supply. It seems they made improvements over the Aiyima A07 but I am not thrilled with its sound unless I tweek the eq knobs a bit. Seems powerful and clean but lacks low end when the eq is off. Think they should get rid of the bluetooth and maybe even the EQ knobs just make it a power amplifier. I may send it in to Amir for testing because I probably won't be using it. Anyone else tried one of these?
https://www.amazon.com/dp/B08GQL6BJ...abc_6K2HQNAVWN38SSNM328Q?_encoding=UTF8&psc=1

 

[IowAudio]

Here's a bunch of pics.

 

[f1shb0n3]

I have one and used it for awhile with Elac DBR-62 speakers, now on the patio with Revel M80XC speakers. Works great for both and there's no issue with the low end - when the treble knob is all the way to the left it acts like a power amp with no EQ applied. What you are probably experiencing is comparing EQ vs no EQ and of course with EQ you get a boost in the bass which makes it seem that bass is weak without EQ.
I've also done a comparison of the frequency response on the Elac DBR-62 with Nobsound TPA3255 vs March Audio P452 (Purifi-based state of the art amp) and there was no measurable or audible difference.

The EQ knobs are very useful btw - my Revel M80XC do have a sharp drop off below 100Hz which matches Amir's measurement of M55XC and the sound was very bright and lacking "body" - here's my full spectrum pink noise RTA measurement with REW and calibrated UMIK-1 compared against my preferred Harman-esque target:

With Treble at 3pm, Mids at max and Bass at slightly below max on the amp the sound became full and pleasing, here's the post EQ adjustment measurement:

Still not perfect, but very listenable and enjoyable. Tried a parametric EQ to perfectly match the target and got a slight improvement, so an order of Minidsp 2x4 HD is on the way.

My point is though that having EQ controls on the amp is a very good thing that can transform your sound for the better and makes this amp a great value for the price.

 

[IowAudio]

Still loses to much volume when the EQ is on. Seems like to me the tone controls all have to be at 3 o'clock or max to get volume back to when the EQ is off. To me makes more sense to just leave it off and EQ with my minidsp or EQ APO. Even using the Bluetooth most phones have decent EQ built in. This way I get all the power and still have EQ if I want. Not really a fan of tone knobs anyway. I'll be selling and replacing with Aiyima A-08, new big brother to the loved A-07.

 

[f1shb0n3]

Still loses to much volume when the EQ is on.

This is inevitable no matter what EQ you use. Btw just installed a miniDSP 2x4HD as a DAC with that amp and Revel M80XC speakers. Created an EQ with REW based on my measurement and now I get my preferred Harman target perfectly matched and very happy with it. I had to lower the overall level by 6dB because I'm boosting low end and certain frequencies so volume loss with EQ where a lot of boost is needed can't be avoided.

What speakers are you driving with that amp btw? I tried it for Infinity R263 towers and it could not drive them properly - the low end was anemic with Nobsound TPA3255 while Purifi amp drove them perfectly, objectively confirmed with pink noise RTA measurement.

 

[Ralferator]

I got this Nobsound TPA3255 off Amazon for $109. Its same thing as the BRZHiFi both based on the TPA3255 and a built in power supply. It seems they made improvements over the Aiyima A07 but I am not thrilled with its sound unless I tweek the eq knobs a bit. Seems powerful and clean but lacks low end when the eq is off. Think they should get rid of the bluetooth and maybe even the EQ knobs just make it a power amplifier. I may send it in to Amir for testing because I probably won't be using it. Anyone else tried one of these?
https://www.amazon.com/dp/B08GQL6BJ...abc_6K2HQNAVWN38SSNM328Q?_encoding=UTF8&psc=1

I saw a review on Aliexpress once (can't find it at the moment) where somebody measured the frequency response and the low end was missing a LOT below 100hz with this amp with EQ off. With EQ on it was ok. I don't know if all those amps have this trouble but some reviewers complained about it. I think daniboun here in the forum has the amp and was satisfied, but he changed the op amps. I don't know if it could be the reason, but maybe fake op amps are responsible. From the measurements i saw i would not use the amp with the EQ turned off.

 

[f1shb0n3]

Revel is showing specs with -3dB @ 60Hz - could it be that your amp also has a problem with the low end or did you compare with another amp?

I did not test with another amp, but it's a good point - I will try it out and compare with Nobsound. Disconnecting and moving my primary Purifi amp from my desk is a chore though and I also need to do another measurements in a quieter time which is hard with a major freeway close to the house, gotta be in early AM hours.

Maybe we need a proper APx555 measurement on the Nobsound amp to confirm for sure if there's an issue with the low end when EQ is off.

 

[Ralferator]

I did not test with another amp, but it's a good point - I will try it out and compare with Nobsound. Disconnecting and moving my primary Purifi amp from my desk is a chore though and I also need to do another measurements in a quieter time which is hard with a major freeway close to the house, gotta be in early AM hours.

Maybe we need a proper APx555 measurement on the Nobsound amp to confirm for sure if there's an issue with the low end when EQ is off.

Yes that would be nice. I can't find that review with the measurements anymore, but i remember that it looked like a high-pass filter

 

[IowAudio]

Okay, did some quick REW measurements with my Dayton UMM-6 mic @ 1ft comparing my main amp Harman Kardon HK3490 vs Nobsound 3255 using some of my DIY speakers. Its pretty much exactly what I heard when test listening. Nobsound lacks bass and looses a few db when tone control is enabled. Bass on Nobsound has to be at 3oc to match stock HK3490 but still lacks a few db mids through treble. This can probably be fix by setting all 3 tone controls to 3oc. (Nobsound Default vs EQ) graph the tone knobs are all at 12oc. In order to keep the full output I have better results leaving tone controls off and making adjustments via miniDSP or EQ APO. Either way I'm wondering if there may be something wrong with my Nobsound 3255.

 

[f1shb0n3]

Did you do measurements with a frequency sweep or pink noise with RTA? My guess is that frequency sweep would measure the linearity of the amp while pink noise with RTA will also measure the power capacity of the amp as it might be lacking bass for lack of power to drive the speakers. My reasoning is that even underpowered amp will be able to produce a single frequency in the lows, while with pink noise it engages the whole spectrum and would need more power to drive the lows as they take more power to drive the big driver to move.

Btw the recommended smoothing with REW is "variable" instead of "psychoacoustic" for some extra precision.

In any case I would suggest you try the other method (frequency sweep or RTA) too and compare. I will do the same measurements this weekend to compare Elac DBR-62 and Infinity R263 with Purifi amp vs TPA3255 amp both with frequency sweep and RTA. I'm curious to get to the bottom of this mystery and if upgrade if I have a badly designed amp. The amp has always sounded great and is now awesome EQ'd with miniDSP 2x4HD on Revel M80XC outdoor speakers. Technical flaws won't be tolerated in my system though!

 

[f1shb0n3]

Or maybe it's time to upgrade to Motu M4 or RME ADI-2 Pro and learn how to do amp measurements myself? The rabbit hole is endless with this hobby

 

[Ralferator]

Okay, did some quick REW measurements with my Dayton UMM-6 mic @ 1ft comparing my main amp Harman Kardon HK3490 vs Nobsound 3255 using some of my DIY speakers. Its pretty much exactly what I heard when test listening. Nobsound lacks bass and looses a few db when tone control is enabled. Bass on Nobsound has to be at 3oc to match stock HK3490 but still lacks a few db mids through treble. This can probably be fix by setting all 3 tone controls to 3oc. (Nobsound Default vs EQ) graph the tone knobs are all at 12oc. In order to keep the full output I have better results leaving tone controls off and making adjustments via miniDSP or EQ APO. Either way I'm wondering if there may be something wrong with my Nobsound 3255.

Maybe ask Daniboun, here in the forum. He has experience with a lot of TPA3255 amps and with this one too. But he changed the op amps. I also wonder if all those amps are like this or if it's just a few. But it is for sure that it is not only jours.

 

[IowAudio]

Haven't gotten a chance to do pink noise measurements but tried with other speakers and I'm getting the same thing. Tried Sony CS5, JBL Stage A130, BIC DV62Si. All lack low end with this Nobsound 3255 with tone controls off....

 

[IowAudio]

Did a quick pink noise test between the Nobsound and HK3490. Same thing as before, the nobsound starts dropping off at 40hz.... Its not a perfect test but does reflect what I'm hearing.

 

[Lorenzo74]

What about the power supply? How many Amps?

 

[IowAudio]

I provided pics at the beginning of the thread. The built in power supply says 36v @ 9.5amps. Should be plenty of power.

 

[Lorenzo74]

I provided pics at the beginning of the thread. The built in power supply says 36v @ 9.5amps. Should be plenty of power.

Agree this does not seem a power issue. Early bass roll off generally could be caused by small coupling capacitors.
I recall johnaudiotech did a good video on this.

Hope you find useful, hope JAT will join this forum.
my Best
L.

 

[Shiva]

I am contemplating getting this to try out for fun. The topology is quite different from other tpa3255 amps, which have big copper coils on display, as well heatsinks inside. Does that mean this is designed to put out less power. Is the 300 watts a side a myth with this one like it is with the A07?

 

[IowAudio]

Because of the 40hz low end roll off I can't keep or recommend this amp. If you want one to mess with fine but otherwise nope. Testing this next to a 250w x2 @4ohm hypex amp it got killed. The hypex definitely had more power. The power supply in the Nobsound is 36v @ 9.5amps = 342watts if it were 100% efficient which is impossible. So there's no way this amp is pushing 300w x2. I'd guess maybe 100 x2 of clean usable power into 4ohms idk... Here's my YouTube video on it

 

[gasolin75]

Because of the 40hz low end roll off I can't keep or recommend this amp. If you want one to mess with fine but otherwise nope. Testing this next to a 250w x2 @4ohm hypex amp it got killed. The hypex definitely had more power. The power supply in the Nobsound is 36v @ 9.5amps = 342watts if it were 100% efficient which is impossible. So there's no way this amp is pushing 300w x2. I'd guess maybe 100 x2 of clean usable power into 4ohms idk... Here's my YouTube video on it

What to chose instead for the same price, it's very nice to have the power supply inside of the amp, S.M.S.L A300 is almost 50% more expensive