Fosi M03 / Aiyima 3001 / Nobsound G2 Pro mono sub amp review

[JohnnyAudio]

I have a dual voice coil sub. If I use 2 amps, one for each voice coil, do I get more DB from the speaker?

 

[Franzois]

Thanks for the review!

I just got the Nobsound/Douk version.

The board layout is noticably different and, most importantly, the main capacitors are rated for 25V and the provided power supply is 19V 5A.
You can't use a beefier power supply with this one.

Even though it is cheaper, I'll return the Douk and get a Fosi.

Cheers

 

[gaussianmist]

Thanks for the review!

I just got the Nobsound/Douk version.

The board layout is noticably different and, most importantly, the main capacitors are rated for 25V and the provided power supply is 19V 5A.
You can't use a beefier power supply with this one.

Even though it is cheaper, I'll return the Douk and get a Fosi.

Cheers

Could you have purchased the G2 rather than the G2 PRO?

 

[gaussianmist]

From the Nobsound Manufacturer:
Packing List

• 1* G2 PRO Mono Power Amplifier
• 1* 32V/5A Power Supply

 

[Franzois]

Could you have purchased the G2 rather than the G2 PRO?

Yes, you're right. I didn't even imagine that they could sell 2 slightly different models (!).

Could anyone confirm that the Nobsound G2 Pro is exactly the same as the Fosi tested here (modulo the gain switches)?

Thanks.

 

[gaussianmist]

Yes, you're right. I didn't even imagine that they could sell 2 slightly different models (!).

Could anyone confirm that the Nobsound G2 Pro is exactly the same as the Fosi tested here (modulo the gain switches)?

Thanks.

I'M getting my Nobsound G2 Pro today. It was on sale at Amazon for about
$68.

 

[Franzois]

I'M getting my Nobsound G2 Pro today. It was on sale at Amazon for about
$68.

I'll wait for your input then.

 

[gaussianmist]

I'll wait for your input then.

I guess the weather has been a factor as I still haven't received the Nobsound from Amazon. I see that the Aiyama is available at Ali Express for about $54 (including shipping) with the 32 volt PS.

 

[gaussianmist]

I'll wait for your input then.

I got my Nobsound yesterday and the only differences among the 3 that I can see are the gain switches which are very accessible at the bottom of the unit and (from the manual) low pass ranges from 40-300 Hz. Also, the bass frequency and volume control knobs are click-type making it easier to regain your setting if accidentally changed. I'm using the unit to replace the subwoofer amp (which failed) in my Def Tech STS loudspeaker. I re-wired the STS making it a fully passive speaker and am using REW to finesse the Nobsound settings.

 

[Franzois]

Following your advice, I bought the Aiyima which was significantly cheaper on AE with the 36V PSU than the Nobsound one (~50 vs 75€). Actually, I may just use the board in my velodyne CHTR sub, since the high-pass line output still seems to work (the power amp of the board is dead). My only problem will be to find a way to put the Aiyima board on the heatsink of the sub.

 

[gaussianmist]

Following your advice, I bought the Aiyima which was significantly cheaper on AE with the 36V PSU than the Nobsound one (~50 vs 75€). Actually, I may just use the board in my velodyne CHTR sub, since the high-pass line output still seems to work (the power amp of the board is dead). My only problem will be to find a way to put the Aiyima board on the heatsink of the sub.

Make sure that it's not the JUNIOR Aiyima.

 

[Ale10]

Hi all,

do you think one of these Amplifier is good to move a subwoofer Ciare CS253 (200w RMS 2ohm, but it can play also at 100w RMS 4ohm). Thank you.

 

[JohnnyAudio]

Yes, I use similar FOSI M-03 with CSS SDX12 - 12" XBL^2 Subwoofer and it sound good. It does not sound overpowered like many subs do.

​

 

[theREALdotnet]

do you think one of these Amplifier is good to move a subwoofer Ciare CS253 (200w RMS 2ohm, but it can play also at 100w RMS 4ohm). Thank you.

It depends, 2 ohms is probably too much to ask but 4 ohms should be fine. Also, what's expected from the subwoofer? Is it meant to shake a large home theatre, or is its job filling in the bottom end of a stand-mount stereo setup?

 

[Ale10]

Thanks for the replies.

The subwoofer is going to help a pair of Lonpoo LP42s that I have on my desk. The speakers are decent for what they cost, but they are practically absent in the bass and unbalanced in the highs. I had this Ciare subwoofer that was mounted on my car many years ago, and so I thought I would give it a new life. The subwoofer is a double voice coil with 200W RMS at 2 ohms, but since I don't need all the power I disconnected a voice coil to make it go to 100W RMS at 4 ohms.

In the end I bought the Aiyima A3001 and the situation improved a lot. It's definitely not a HiFi configuration, but now I have more presence in the low-mid range. No power problems since I have to keep the amplifier volume at less than half.

Thanks again for the help

 

[orange260z]

Thanks for all the info on this thread. Do you think one of these would be suitable to power a Tannoy TS10 with a dead amp? It's a tiny 10" sealed sub that came from the factory with a 300W RMS BASH amp, so quite a bit more power. I'm struggling to find a plate amp that fits and is cost effective here in Canada.

 

[AresLuna]

A wonderful review and thread overall. Could we have some input about the amplifier's quality as a SUB amp please? I am facing a situation where my precious sub's plate amp is dying. It is a great sub, extending to really deep bass due to the VIFA 10" 6ohm driver which is in perfect condition. The plate amp has started humming when active (hum stops when it goes in auto standby - no LFE signal through RCA connection) and also sometimes it fails to activate if the LFE signal is not powerful enough (missing some of the bass effect for a second or two) and also when it auto activates some times it produces a brief clip/distortion noise.

The repair would cost about the price of a new Nobsound G2 Pro or maybe even more. I don't want to replace my subwoofer, because the bass it produces is one of the best i have heard for its price class even compared to much more expensive offers by other respectable makers. So why not make it passive and give it a new life?

Some people have reported back that they are using this amp to revive their subwoofers with blown plate amps, and some of those reports mention expensive subs like Velodyne, Klipsh, SVS, REL, Martin Logan etc. These plate amps contain some seriously designed circuitry and replacements for those often cost hundreds or over a thousand of dollars in some cases. Can the Fosi/Aiyima/Nobsound solutions provide a decent replacement?

Can you people report on the quality of these "replacement" amps (bass control, tightness, overall bass quality) compared to the original plate amps of your subwoofers?
Are you experiencing hums or other compromises with the sound quality?

Thanks in advance!

 

[AresLuna]

I pulled the trigger for a Nobsound G2 Pro and a separate 48V 5A GaN power supply. I also received the 32V 5A standard included power supply. I also got some switching power supplies mainly purposed for laptops. An ASUS 19V 6.32A, a Li Shin 24V 5A, and a Toshiba 19V 6.32A.

I ran numerous tests with two of my subwoofers that have dead plate amps. One is a Boston Acoustics CS Sub10 (with a custom made Boston 10" 4Ω driver - measures about 2.7Ω on the multimeter). And the other is a Roister Powerbass 125 (old Greek reputable brand) which contains an older but widely available (back at that time) Vifa 10" 8Ω driver that measures about 5.8Ω with the multimeter.

I do have some observations to report.....:

From the above power supplies, I can use the 48V 5A, the 32V 5A and the ASUS 19V 6.32A. The Li Shin and the Toshiba produced audible background noice at low volume though, possibly some kind of ground loop? I tested this with different sources and although the noise changed somewhow, it remained existent in all tests with those two power supplies.

I set the Nobsound G2 Pro at 36dB input gain. Volume Knob and cutoff frequency knob set right in the middle.

Now, starting with the Boston CS Sub10 (Boston 10" 4Ω driver) downfiring ported design :

- 32V 5A included power supply causes the Nobsound G2 Pro to go into protection mode even without an apparent reason. It could be during a sudden but loud bass sound or during a low volume but consistent bass part of a movie. During a 2 hour movie, i had to switch off and then on the Nobsound, eight (8) times.

-48V 5A GaN power supply did the same thing but less often.

-19V 6.32A ASUS power supply worked wonderfully, with this the subwoofer could output heavy bass at a very satisfying volume for hours without the Nobsound G2 Pro going into protection mode, no matter what the music programm was, be it movies with heavy explosions and heavy bass effects or multichannel music containing LFE as well.
I watched 3 movies back to back, and i didn't have a single problem with this one.

Also, the other two noisy power supply bricks worked well without the Nobsound entering protection mode during a 30 minute test.


Bass performance was actually pretty good with the Nobsound providing a flat and neutral tight and well controlled bass. I didn't experience any distortion or clipping. Clean and good sounding bass. The Nobsound actually performed much better than the Boston plate amp in my subjective opinion and from what i remember when the plate amp was working well (much better at the very low frequencies and more energetic without being too boomy).

It seems the TDA3255 chip doesn't like the Boston 4Ω driver with the 32V and 48V power supplies, maybe because it goes much lower than the nominal impedance and this causes the chip to trigger the protection mode.


Next up is the Roister Powerbass 125 with the Vifa 10" 8Ω driver front firing, back ported design

-32V 5A included power supply

AND

- 48V 5A GaN power supply , BOTH were very good in general BUT during some powerful very low frequency parts of a movie, the driver would produce strange thumping sounds.

When i heard those i immediately stopped any audio playback in order to protect the driver from being damaged.

The only solution was to use the dip switches to revert back to 32dB GAIN (bottom of the Nobsound G2 Pro) and lower the subwoofer level through my AVR's menu or turning down the Nobsound volume knob.

- The ASUS 19V 6.32A power supply worked amazingly well, with both GAIN settings and at every volume level, the Roister subwoofer / Nobsound G2 Pro produced very good results without thumping noises or anything else.

I decided to give it a shot and i did a partial repair on the Roister subwoofer original plate amp, repairing some cold solder joints and brought it back to life (although haven't solved some of the auto on/off popping sounds and some ground loop noise yet, as i don't have any schematics in hand).

I was able to test both the plate amp and the Nobsound G2 Pro solution and although both are actually pretty good, the original plate amp sounds somewhat better with a fuller bass which i believe has to do with the voicing of the amplifier. I believe some more sophisticated subwoofers contain specialy tuned plate amps with EQ applied on the boards, matching with the overall design and the selected driver giving the subwoofer a distinct character and sound.

The Nobsound G2 Pro gives a great bass and of course it can revive subwoofers with dead plate amps, and it can do this for only a fraction of the cost of a replacement plate amp, or even in cases a repair is not even possible.

But because of being neutral sounding, without applying any EQ, it may sound worse if combined with specific drivers and cabinet designs as it lacks the fine tuning that the manufacturer intended for a particular design and subwoofer model. I still haven't decided if i like the bass sound i am getting....it has given breath to my subwoofers for sure, but it's a different "kind of breath". This is for every future buyer, so that you keep in mind you will be getting a completely different sound than the one you were used to!!!


Four questions though......

1) Can anyone share some knowledge about why the Nobsound G2 Pro entered protection mode with the Boston 4Ω 10" driver and the 32V and 48V power supplies, but not with the 19V one?

2) Why did the Nobsound make the Vifa driver distort so much with those thumping loud sounds when used with the 32V and 48V power supplies?

3) I have set the crossover on my AVR at 80Hz for the subwoofer out. Why the crossover knob on the Nobsound makes a seriously audible difference even when turned more than the middle (which is apparently already higher than 80Hz at the middle position?

4) Any solutions for finetuning the EQ settings for this frequency range (say 20-120Hz) to somehow "voice" the Nobsound to my liking (except the AVR's EQ) ?

 

[theREALdotnet]

1) Can anyone share some knowledge about why the Nobsound G2 Pro entered protection mode with the Boston 4Ω 10" driver and the 32V and 48V power supplies, but not with the 19V one?

When the signal amplitude was high enough at a low-impedance frequency spot then the sub would have drawn too much current and put the amp into protection. With the 19V supply the current would have been limited by the supply voltage, so instead of triggering protection, the output would have just been clipped.

2) Why did the Nobsound make the Vifa driver distort so much with those thumping loud sounds when used with the 32V and 48V power supplies?

With the 32V and 48V supplies the amp likely delivered more power than the subwoofer could handle.

3) I have set the crossover on my AVR at 80Hz for the subwoofer out. Why the crossover knob on the Nobsound makes a seriously audible difference even when turned more than the middle (which is apparently already higher than 80Hz at the middle position?

The Nobsound's crossover is not very steep, but rather a gentle slope.

4) Any solutions for finetuning the EQ settings for this frequency range (say 20-120Hz) to somehow "voice" the Nobsound to my liking (except the AVR's EQ) ?

Yes, measure the frequency response with REW and design a filter to flatten it. Use that filter with your music player or EQ software. Alternatively (what I'm doing), let Dirac take care of bass EQ.

 

[AresLuna]

When the signal amplitude was high enough at a low-impedance frequency spot then the sub would have drawn too much current and put the amp into protection. With the 19V supply the current would have been limited by the supply voltage, so instead of triggering protection, the output would have just been clipped.



With the 32V and 48V supplies the amp likely delivered more power than the subwoofer could handle.



The Nobsound's crossover is not very steep, but rather a gentle slope.



Yes, measure the frequency response with REW and design a filter to flatten it. Use that filter with your music player or EQ software. Alternatively (what I'm doing), let Dirac take care of bass EQ.

Thank you so much for the reply!

About the question 1), the Nobsound would get into protection mode even during quiet parts with low frequency effects present but not loud at all. I guess that must have been that low-impedance frequency spot you mentioned in your reply.

But why didn't that happen during previous sequences in the movie where there were extremely loud low frequency effects like explosions and continuous heavy bass for almost 10 minutes? Also, the Nobsound G2 Pro didn't even feel warm to the touch, reaching about 32 C degrees, mainly on the sides of the outer metal shell, so no thermal runaway as well.


2) Yes, that makes sense. But using a sound level meter, after isolating the subwoofer alone without the rest speakers of the setup being active, i found out that it happened at the same levels, although the corresponding position of the Volume Knob on the Nobsound changed depending on the power supply used, which is reasonable. Why at the same sound level output the 32V and 48V made the subwoofer driver distort, while the 19V one didn't?

3) You are right, i saw the measurement graphs again on the first page. It is indeed very gentle.

4) I was thinking about that and i believe it is the best approach. But on this setup i am feeding my AVR with multichannel audio through HDMI passing through the original format with the decoding taking place inside the AVR (Dolby / DTS etc). I believe the Dirac approach involves buying a Dirac Live license and of course an equipment change, perhaps a new Dirac AVR? Of course that brings all the benefits of room correction and EQ / Bass management at a completely different level.