Stereo Power Amplifier - issues - Plz help

[elangoas]

Hi All,

At present i have a Sonodyne stereo power amplifier SPA202, an USB-DAC (SMSL IDOL USB DAC) as pre-amplifier with Sonodyne Sonus 1501 BS speakers..

Below are some issues which am facing and need help to fix it..

1) Constant hiss on both the speakers. Since the speakers are 86db efficient, it is not very evident.. The hiss is persistent even when the USB DAC is not connected to the PC.. (Grounding issue? I live in a Flat & have 3 phase connection, the electrician checked and said there is no grounding done)

2) Right speaker output is lesser than the Left.

3) In the evening/night, sometimes there is a loud noise from the right speaker output. Left doesn't make any issues. Juz the usual hiss sound.

4) There is some sort of electrical disturbance (When we switch on fan's & reduce the regulator to slow, there is constant noise in the amplifier).

5) When other electrical appliances like blender (or) mixer (or) Tubelight/CFL (or) washing machine is switched on, there is a bit of disturbance in playback.

Need your help to identify the root-cause and fix the issues...

 

[Nikhil]

It appears that you may have some problems in your home wiring which are affecting your system playback. Short of replacing the entire wiring in your home, the best solution would be to ask your electrician to draw a dedicated line for your stereo system. I would then recommend you install a good power conditioner to clean up the power on this line before feeding it to your stereo.

For the balance issues on left / right channels you will have to look at your volume control or balance control (if the amp has it). Sometimes a simple cleaning of the contact points should rectify the problem. Other more simple areas to look at would be checking the speaker cable connections.

Hope this helps.

 

[MaSh]

Did you try another power point?

Dac as pre amp means, your volume control is on the dac? Does reducing volume, reduce the hiss?

Try disconnecting one device at a time to see if they make a difference? Should help pick the culprit.

Also check for any power cable intertwined with an audio cable?

Did this start recently? If yes, what changed recently on this phase? Try pulling wires from a phase which does not power home appliances. This is known to help.

MaSh

 

[elangoas]

It appears that you may have some problems in your home wiring which are affecting your system playback. Short of replacing the entire wiring in your home, the best solution would be to ask your electrician to draw a dedicated line for your stereo system. I would then recommend you install a good power conditioner to clean up the power on this line before feeding it to your stereo.

For the balance issues on left / right channels you will have to look at your volume control or balance control (if the amp has it). Sometimes a simple cleaning of the contact points should rectify the problem. Other more simple areas to look at would be checking the speaker cable connections.

Hope this helps.

Am not sure how much of an effort it is to re-do the entire wiring for home.. I will request the local technician to drop in and give me the effort estimate.

Drawing a dedicated power line from one of the phases look a good idea.

How much would a power conditioner cost ?

Did you try another power point?MaSh

Yes

Dac as pre amp means, your volume control is on the dac? Does reducing volume, reduce the hiss? MaSh

Yes. Volume control is on DAC. Nope it doesn't.. The noise is static..

Try disconnecting one device at a time to see if they make a difference? MaSh

Yes. I tried that.. But didn't disconnect the modem adaptor..

Also check for any power cable intertwined with an audio cable?

Did this start recently? If yes, what changed recently on this phase? Try pulling wires from a phase which does not power home appliances. This is known to help. MaSh

Try to separate cable inter-winds.. But no help...

The issue was there earlier, but was using it for front height channels with the AVR.. It didn't affect much..

Yes.. Will try to pull a separate line for this and see if that helps..

 

[spandan414]

1) Constant hiss on both the speakers. Since the speakers are 86db efficient, it is not very evident.. The hiss is persistent even when the USB DAC is not connected to the PC.. (Grounding issue? I live in a Flat & have 3 phase connection, the electrician checked and said there is no grounding done)

Hi Elangoas,

With volume set to a normal listening level, how close to the speaker must you be to hear the noise?

Regards,
Sam.

 

[elangoas]

Hi Elangoas,

With volume set to a normal listening level, how close to the speaker must you be to hear the noise?

Regards,
Sam.

Within 1 feet distance from the speakers, the noise is evident..

My listening position is approx 12 - 13 feet from the speaker, sometimes the hiss is evident...

Edit:
Forgot to add this...There is a huge tower near home (guess radio tower), approx away from home.. Could this also be one of the reasons ? If so both channels should get disturbance..

 

[VRavichandar]

Has the electrician measured the Neutral to ground voltage in your Mains power sockets with a DMM and how much was it?

 

[elangoas]

Has the electrician measured the Neutral to ground voltage in your Mains power sockets with a DMM and how much was it?

Nope...Not sure if he has the equipment..I could ask my friend to check that..

 

[jls001]

Get grounding installed. You're operating dangerously.

 

[elangoas]

Get grounding installed. You're operating dangerously.

Sure.. But could you please enlighten me the consequence in the absence of grounding...

 

[magma]

are you using a preamp ?

which one ??

 

[elangoas]

are you using a preamp ?

which one ??

Am using the USB DAC as Pre-Amp, using the 3.5mm out from the DAC and connected to RCA inputs on power-amp.

 

[tuff]

Which USB DAC ?

 

[keith_correa]

Sure.. But could you please enlighten me the consequence in the absence of grounding...

Let me google that for you

 

[Nikhil]

Am not sure how much of an effort it is to re-do the entire wiring for home.. I will request the local technician to drop in and give me the effort estimate.

Drawing a dedicated power line from one of the phases look a good idea.

How much would a power conditioner cost ?

I use an APC SmartUPS that offers battery backup and regeneration.
The model offers battery backup, power factor correction, sine wave regeneration and frequency locking.
Price was approx Rs 35K. However it is a discontinued model.

You should contact a local power treatment expert for advice.
Definitely worth the investment in time and money spent.

 

[MaSh]

Am using the USB DAC as Pre-Amp, using the 3.5mm out from the DAC and connected to RCA inputs on power-amp.

Is that a headphone amp? Does it have a gain setting, what is it set to? Does it make a difference when toggled between low and high?

Do the speakers hiss when the audio cable o's unplugged from this?

MaSh

 

[elangoas]

Which USB DAC ?

It is SMSL IDOL USB DAC - Here is the link to the product https://www.massdrop.com/buy/smsl-idol?mode=guest_open

Let me google that for you

Thanks..

I use an APC SmartUPS that offers battery backup and regeneration.
The model offers battery backup, power factor correction, sine wave regeneration and frequency locking.
Price was approx Rs 35K. However it is a discontinued model.

You should contact a local power treatment expert for advice.
Definitely worth the investment in time and money spent.

Thanks for the inputs. I too have APC inverter @ home.. I guess the usual ones.. Anyways, i will fix the grounding issue first, then draw a separate line for stereo and if nothing works, will look for power conditioner..

 

[elangoas]

Is that a headphone amp? Does it have a gain setting, what is it set to? Does it make a difference when toggled between low and high?

Do the speakers hiss when the audio cable o's unplugged from this?

MaSh

Yes.. It is a headphone amp.. No, it doesn't have gain setting.

The toggle on the DAC is volume control..

Yes. Even when the DAC is unplugged from the power amp, there is hiss in the speakers..

 

[magma]

Yes.. It is a headphone amp.. No, it doesn't have gain setting.

The toggle on the DAC is volume control..

Yes. Even when the DAC is unplugged from the power amp, there is hiss in the speakers..

when you say unplugged do you mean powered off
or unplugged as in RCA disconnected

please try the setting WITHOUT the headphone amp /dac in the chain

use direct from computer / laptop and use windows to control volume

is the hiss still there in this condition ?

 

[elangoas]

when you say unplugged do you mean powered off
or unplugged as in RCA disconnected

please try the setting WITHOUT the headphone amp /dac in the chain

use direct from computer / laptop and use windows to control volume

is the hiss still there in this condition ?

There is no power on & off button for the DAC.. It has only the volume controls.. When connected to PC, it powers on... I was referring to disconnecting the DAC's Micro USB port from PC..

I tried controlling the volume of DAC from windows, it doesn't allow. It has to be controlled externally on the DAC's volume key's..

The hiss is persistent even when the DAC is not connected to power amp...(When only the power amp + speakers are connected) It is faint.. But gets louder sometimes...