Subwoofer hum - home system - Please help

[pubwie]

Any advice on how to eliminate subwoofer hum?

I posted a video explaining the issue in more depth while showing the amplifier circuitry here:

I tried to follow the tips by Adam Francis Link to video:

My conclusion is that it is a grounding issue, but my knowledge falls short of how to actually go about fixing it.

• I replaced the capacitors
• I tried grounding the line-in RCA inputs to the sub body.

What else would help?

THA

 

[DigitalDawn]

Try disconnecting your cable TV or satellite cable from the set top box. If the hum goes away, a simple Jensen transformer will fix the problem.

 

[pubwie]

Thanks for the reply.
I disconnected everything except the power but the hum persists..
Would a transformer replacement be the only solution?

Any other possible DIY that might work?
I ask because in South Korea finding parts is bloody difficult and not many manufacturers and suppliers ship here, specially during covid times..

 

[Speedskater]

a] what type of interconnects (RCA, XLR) ?
b] with no input interconnects to your amp/receiver.
c] place the sub near the amp/rec.
d] power both from the same AC wall outlet.
e] using a short interconnect from amp/rec to sub, does it hum?

 

[pubwie]

A) RCA (generic)
B) the sub starts off with no hum. after 5mins it hums whether it is connected to a signal or not. (not sure if that refers accurately)
C) the amp is integrated with the sub, or rather, the amp has it's own amp which the RCA and speakers can connect to.
D) i read about the ground loop issue, everything is powered from 1 AC wall outlet.
E) sub + amp are housed together, the RCA from the music source (laptop) is 1.5meters long

what comes to mind?

 

[lovinthehd]

I've had bad rca cables cause sub hum, did you try another cable? I also had sub amps start to hum before they failed.

 

[pubwie]

I've tried two cables. same result.
The sub keeps humming even after I disconnect the cable..

 

[lovinthehd]

I've tried two cables. same result.
The sub keeps humming even after I disconnect the cable..

It's a hum that comes thru the driver rather than just a buzzing in the amp itself, yes?

 

[pubwie]

yes, i think so, the sub speaker that is.

through the auxiliary speakers, no humming

 

[TLS Guy]

yes, i think so, the sub speaker that is.

through the auxiliary speakers, no humming

Your problem is that you sub is defective. What you are experiencing is a common failure mode of switching power supplies in subs. The amp in your sub needs replacement, or you need a new sub.

 

[pubwie]

if that is the only conclusion and no fix possible, then it is unfortunate for me.
thanks for all the feedback everyone

 

[TLS Guy]

if that is the only conclusion and no fix possible, then it is unfortunate for me.
thanks for all the feedback everyone

Unfortunately that is the only possible conclusion.

 

[pubwie]

Hey guys.

I tried to buy and connect a ZK-TB21 TPA3116D2 amplifier board (50WX2+100W, 4-8Ω) to the Britz subwoofer (20watts, 4Ω ) and satellite speakers (2x8watts, 4Ω ), but getting audio cutouts.

Using these together:

+

* TPA3116D2 +
* 9-24V 3A 72W AC/DC Adapter


Problem:
* Satellite speakers play sound with no problem, but when low frequencies kick in during my test, the little amp cuts the audio.
* I tried powering it with 12v-24v 3a power brick.

Video:

Notes:
* The subwoofer speaker is wired directly to the TPA3116D2 terminal from the speaker.
* Bass volume, Frequency cutoff is set to zero and then turned up. Once bass kicks in the thing stops producing sound.

Question:
1) What do you think is the problem?
2) Is the wiring okay?
3) Wrong power supply rating, perhaps 5amps?
4) Blown sub speaker? If so, how can I test it?


This is turning into a learning experience. Any help would be greatly appreciated.

 

[TLS Guy]

Hey guys.

I tried to buy and connect a ZK-TB21 TPA3116D2 amplifier board (50WX2+100W, 4-8Ω) to the Britz subwoofer (20watts, 4Ω ) and satellite speakers (2x8watts, 4Ω ), but getting audio cutouts.

Using these together:
View attachment 48684+View attachment 48685
* TPA3116D2 +
* 9-24V 3A 72W AC/DC Adapter


Problem:
* Satellite speakers play sound with no problem, but when low frequencies kick in during my test, the little amp cuts the audio.
* I tried powering it with 12v-24v 3a power brick.

Video:

Notes:
* The subwoofer speaker is wired directly to the TPA3116D2 terminal from the speaker.
* Bass volume, Frequency cutoff is set to zero and then turned up. Once bass kicks in the thing stops producing sound.

Question:
1) What do you think is the problem?
2) Is the wiring okay?
3) Wrong power supply rating, perhaps 5amps?
4) Blown sub speaker? If so, how can I test it?


This is turning into a learning experience. Any help would be greatly appreciated.

That amp is totally inadequate for driving a sub, and it is being over driven and triggering thermal cut out.

You need something much more potent than that piece of misery to power a sub.

 

[pubwie]

That amp is totally inadequate for driving a sub, and it is being over driven and triggering thermal cut out.

You need something much more potent than that piece of misery to power a sub.

Wouldn't the 100w amp be able to handle the 20w speaker? (i'm not sure if this question makes sense. I have very limited knowledge about this stuff)

If not, how would one go about calculating what amp rating is needed to do so?

 

[TLS Guy]

Wouldn't the 100w amp be able to handle the 20w speaker? (i'm not sure if this question makes sense. I have very limited knowledge about this stuff)

If not, how would one go about calculating what amp rating is needed to do so?

Your trouble is that you are dealing with dishonest manufacturers. There is no way that amp is 100 watts. It will be in the 2 to 5 watt range about 12 watts at the most, but much more likely in the 5 watt range. I can find no information on the Britz sub. But I see other products from the company and that also seems a bottom feeder company.

The problem is you are dealing with equipment that has a marginal chance of providing any useful service at best.

 

[pubwie]

Your trouble is that you are dealing with dishonest manufacturers. There is no way that amp is 100 watts. It will be in the 2 to 5 watt range about 12 watts at the most, but much more likely in the 5 watt range. I can find no information on the Britz sub. But I see other products from the company and that also seems a bottom feeder company.

The problem is you are dealing with equipment that has a marginal chance of providing any useful service at best.

I hear you. I have seen this amplifier being recommended on various forums lately, and the reviews seemed enough to justify a purchase. Seems that it was a mistake now.

I do have the smaller 2x100W TPA3116 from the same company that does work fine, but it has two channels and no frequency control. It works fine with another set of speakers, but yeah, want to try and get the sub working before investing in any higher-end speakers or system.