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Stereo Balance problem (L R)


Qwiz
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Salutations. I recently stumbled upon the following:

When trying to set the Balance setting all the way to the Left, the Left and the Right speaker are a few db down (almost to half volume), but overall same db level (L and R). Analog when setting the Balance all the way to the right. Same thing happens.

Prior I have installed a Hifonics amp and used its balanced inputs for the signal. For this I extra needed an RCA to BLT device, Hifonics too.

L and R RCA HU outputs go into this small device. From there it outputs one single balanced cable that goes into the amp's balanced input.

 

The problem is that there is no recognition between L and R. I most definitely did something wrong (checked 10 times).


Would you guys have any suggestions?

 

 

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Posted (edited)
On 6/6/2022 at 3:59 PM, audiofanaticz said:

I guess it would help if you listed the model numbers of both devices you are using, also why are you using balanced anyways?

It is a Hifonics Andromeda X4.

 

After a more through inspection, came to the conclusion it's the amp. There is unfortunately no stereo separation. Bought it new.

 

I am using balanced because with my last amp I have been using RCAs and had a slight noise in the tweeters. Although this might have more to do with that amp, I have decided out of safety reasons (paranoia) that for this new amp I would use its balanced inputs. For which I needed another device, small, Hifonics BLT4. This particular model has RCA inputs and BLT outputs. It is present by other manufacturers under their brand name, such as ESX. I said why not using that.

 

I had to disassemble the whole car and redesign the amp rack took me a long time. And all I have is this now

Edited by Qwiz
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Posted (edited)

After further investigations I have come to the following conclusion:

 

With no speaker connected to the amp, the balance setting left right or center seems to be working.

Once speakers get connected, this balance setting becomes useless. It almost has no effect. They both continue playing a little bit quieter left or right and louder when set on center.

 

Has this happened to anyone of you guys? Like when you test your amp without speakers everything seems like it should be and once you connect them it's a hell of an issue.

 

Speakers are all in check as well as their cables.

 

This has been tested using an Oscilloscope.

 

Example: Having the balance set all the way to the left we have:

 

Situation 1) No speakers

 

Amp left output: couple of Vrms

Amp right output: zero Vrms

 

Situation 2) With 2 speakers left and right

 

Amp left output: less couple of Vrms than in Situation 1

Amp right output: same as left output, less couple of Vrms than in Situation 1

 

What the hell is this?

Edited by Qwiz
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So my point is your radio is using rca preouts to go into a rca to balance module to give balanced inputs to the amp. 

Seems to be that you can just cut out the balance connection all together and use the rca that you are already having to use.
It seems you are just adding in additional failure points to the system using the balanced inputs and something wacky could be up with the converter, or one of the balance cables, or one of the rca cables feeding the balance converter, etc.

 

As for voltages on each channel not matching up that can be rather normal, its not uncommon for a 2 channel or 4 channel amplifier to have 1 channel that is say 5% ish more than the other due to tolerances of the parts used inside the amp.

1234.jpg

 

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Posted (edited)

I have tested with RCAs only and got the same result. So in theory there is no issue with the balanced inputs, since through both we've got the same issue.

 

Funny thing is when you test the output without speakers, it outputs stereo. Once you hook the speakers up it makes it mono.

 

I have put another amp in, which performed fully stereo. This concludes the Hifonics amp was is in fact the issue here. I was torn apart. I was trying to find reasons elsewhere, put my knowledge under questionmarks, when this whole time this brand new amp was at fault.

 

This amp is not designed by Maxxsonics, but by its "partner" in Europe, Germany, namely Audio Design Germany.

 

I can see that what I am describing might be easily misinterpreted. Perhaps I did not use the right words. So we have two situations.

 

Situation 1: No speakers connected

-with balance setting on the radio set all the way to the left

   --the left outputs X Vrms and the right outputs 0 Vrms

-with balance setting set all the way to the right

   --the left outputs 0 Vrms and the right outputs X Vrms

From this we conclude that the stereo function is OK.

 

Situation 2: Speakers connected

-with balance setting on the radio set all the way to the left

   --the left outputs X/2 Vrms and the right outputs same X/2 Vrms (X being the value from Situation 1)

-with balance setting on the radio set all the way to the right

   --the left outputs X/2 Vrms and the right outputs same X/2 Vrms

From this we conclude that the stereo function is pretty much GONE, because speakers were connected.


By "the left outputs..." I mean the left amp speaker outputs.

I have started this test by premeasuring the Radios RCA L and R Cable Ends, whose outputs were OK. I have switched to another amp and boom we have stereo. Final conclusion: Hifonics amp exerts stereo issues.

 

 

Amp was sent back to them. I'll come with an update soon. See what they have to say about it.

 

I will attach a test sheet if you are curious. Although it is in german and could appear different on your pc or phone due to DOC migration issues, the recorded values should be able to tell what is going on.

Line.doc

Edited by Qwiz
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  • 2 weeks later...
Posted (edited)

Update: They have said they ve diagnosed it and are happy to inform me that it is was a faulty installation from my side, namely a poor bad ground which caused the RCA ground to overheat and melt disconnect from the inside.

 

I can confirm 0%. Now the amp is on its way back. According to this, reconnecting it should cause the same issue.

 

I am going to test the grounds throughly. I wonder if they have already prepared a new excuse once they find my grounds are ok.

 

All of it makes no sense to me it seems all a joke bs. Lucky they got me now to deal with.

Edited by Qwiz
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The ground is ok. And no short in the speakers or similar is present. Everything is in check.

 

On their diagnostic repair sheet:" [...]The burnout of the RCA ground COULD ALSO HAVE BEEN CAUSED by a faulty groundpoint, faulty Power Supply or a short of the speaker cables with the chassis. [...]"

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Its real simple to short out rca signals, it's rather common and people do it all the time.
It falls under user/installer error but no one admits it and says they never did it even though its like the key way for it to happen.
It is hot swapping rca plugs such as unplugging and plugging in rca cables in to the headunit / eq / line driver / dsp / amp / etc when the stereo is powered on.
This seems to be done even more so when a person is trying to troubleshoot a problem and the center pin of the rca (which is positive) touches the outer rca shield (which is negative) and shorts out the circuit. 
So when people post those sorts of symptoms everyone is knowing what the person did even though the blatantly deny ever doing it, let alone owning up to their mistake and learning from it... 

1234.jpg

 

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On 6/28/2022 at 1:45 PM, audiofanaticz said:

Its real simple to short out rca signals, it's rather common and people do it all the time.
It falls under user/installer error but no one admits it and says they never did it even though its like the key way for it to happen.
It is hot swapping rca plugs such as unplugging and plugging in rca cables in to the headunit / eq / line driver / dsp / amp / etc when the stereo is powered on.
This seems to be done even more so when a person is trying to troubleshoot a problem and the center pin of the rca (which is positive) touches the outer rca shield (which is negative) and shorts out the circuit. 
So when people post those sorts of symptoms everyone is knowing what the person did even though the blatantly deny ever doing it, let alone owning up to their mistake and learning from it... 

I have never swapped or taken out any RCAs while the Radio or anything was on. RCAs were carefully handled always when the whole system was completely off. When signal was measured, it was made sure that the measuring clips were safely isolated. Perhaps this amp was already sent in a semibroken state in hopes of the client not noticing its mono output. Be that case, guess these "businessman" in car audio are taking risks when normal clients order and not "specialized" dealers. They bet on it. Or maybe it got broken during shipping somehow. When I first open the package, the styrofoam was broken from aggressive handling.

 

Update: The technician has confirmed that the grounds are fine. Once he is convinced that the Radio RCA ground is also ok, then I have the guarantee that once installed it should work.

Edited by Qwiz
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