Hiss sound from DIY speaker, anyway to remove it ?

[guitar89]

I have build my own amplifier with TDA2009A, its quite same with the datasheet information. Well..... now i used a breadboard to do the job, it produce a hissing sound even i don't connect to anything (also when i connect or play anything).

So its quite sure that it is a amplifier noise, is there any way to remove that noise ?

Last time i modify (from radio to usable input speaker, not tough thought), it also posses the same hissing sound.

The sound is AUDIBLE even when playing low volume music (if you pay attention), but not quite heard it when you crank up the volume.

I'm thinking to solve this problem, before i really solder it and have some listening+complain X.x

Added information :
When the amplifier is on and not pluged in, the hiss sounds became really loud (the previous project won't louder when unplug)

Test the speaker alone without amplifier produce no hissing = NOT LOUDSPEAKER PROBLEM
Test the same source(computer) with good speaker system (brought) = NOT SOURCE PROBLEM

[multisync]

all amplifiers produces hiss. Some produces hiss at a very low level and so you cannot hear it. How close are you to the speakers? At normal listening distance do you hear the hiss?. How efficient are you speakers, the more efficient, the more hiss. Does your amplifier use an input resistor? what value is it? If it is high this can produce some hiss. Is the gain of your amplifier high? The higher the gain the more hiss. Can you get by with less gain? If you short the input of the amplifier does it still produce a lot of hiss? Does your amplifier have a volume control at its input ? Post your schematic.

[guitar89]

hm...... the hissing is audible about distance within 1 meter (typically 0.7 meter away).
Hm... about the efficient thing, kinda weird about it..... higher efficient, higher hiss ? i thought the opposite ^^

My input are direct connect to amplifier IC through capacitor only. no resistor between.

The last speaker have gain of 55db, and this have 36db, but the hissing is kinda at the same level and not much different.

by shorting the input, how to achieve that ? (please briefly describe, thanks )

No volume control, just a direct connection from source to power amplifier circuit.

If said that the amplifier already at certain noise level, is it possible to change the circuit to improve the situation ?

[sreten]

Hi, The gain looks ridiculously high, 1.3K/18R ? Reduce it and more drive, rgds, sreten.

[multisync]

between the input pin, and ground try a 10kohm resistor, also as sreten says the gain of your amplifier is very high try replacing those 18 ohm resistors R2, R4 with 36 ohm resistors. You might even try 72 ohm risitors for R2 and R4( or closest value). This will still give you lots of gain about 18. Most computers will output at least 1 volt. This chip is rated at 10 watts per channel. So even 1/2 volt * 18 will drive your amplifier to clipping. Lowering the gain should reduce the hiss somewhat,

[guitar89]

hm.... i will try to lower it, but the datasheet specified that the gain need to be more 26dB (just 10 dB lower)
Can give the approx. resistance for 26dB ? (afraid of over-lowering makes my amplifier go nuts)

ohh yeah, by shorting input to ground, what it actually achieve ? (just asking X.x have the curiosity to learn about it)

i also kinda heard of some device that can eliminate (lol... almost 100%) noise for this kind of static noise (constant noise volume at all volume), by producing a inverted signal of the noise (pre-recorded) and put into speaker at the same time. Does this really exist ? (forgot where i saw this before)

[indianajo]

There is a "noise cancelling" active headphone that probably has some effect on motor noises and gunshots and firecrackers. Shorting the input to ground will prove whether the hiss source is the amp you built (hiss still there) or is the amp gain amplifying the hiss from the source (computer?) ie hiss gone. Usually turning down the output of the preamp and having high gain on the power amp maximizes hiss.
Could be your new speakers will reproduce high frequencies, and your old ones wouldn't. Cymbal,small bell, triangle grand piano tracks done with good mikes and recording technique are the best ways to test high frequency response of a speaker-amp combination. Loud buzzing and "Ess" noises indicate bad high frequencies. Mushy sound indicates no high frequencies. Use an actual cymbal, small bell, triangle or grand piano to calibrate your ears.

[discrete]

Originally Posted by guitar89

hm.... i will try to lower it, but the datasheet specified that the gain need to be more 26dB (just 10 dB lower)
Can give the approx. resistance for 26dB ? (afraid of over-lowering makes my amplifier go nuts)

R1 = 1300
R2 = 68

G = 20.log(1+R1/R2) = 26.1 dB

I would try 47 ohm (29.1 dB)


Using the PC as source, you should use a power supply that is isolated from the ground to prevent ground loops.

[Tekko]

Hissing can also be HF/RF oscillation, which these old TDA series amp ic's are notorious for.

Personally i'd throw away these TDA pieces of **** and get some LM1875 or even better LM3886, with these you can never go wrong.

[guitar89]

About the shorting, i will use a variable resistor to short it, should i use from low ohm to high ohm, or reverse ? or just directly use 10k ?

Originally Posted by discrete

R1 = 1300
R2 = 68

G = 20.log(1+R1/R2) = 26.1 dB

I would try 47 ohm (29.1 dB)


Using the PC as source, you should use a power supply that is isolated from the ground to prevent ground loops.

aw...... no 47ohm resistor in hand ....... use a variable resistor ?(but i only have 1....)

hm... you said isolated from ground ? (srry, just started to learn alot of things) Can you briefly describe how to achieve ?(or give me a link)

Originally Posted by Tekko

Hissing can also be HF/RF oscillation, which these old TDA series amp ic's are notorious for.

Personally i'd throw away these TDA pieces of **** and get some LM1875 or even better LM3886, with these you can never go wrong.

wowowo.... thats what i'm interested ! any other suggestion ? (other series)
Is there anyway to identify amplifier that is not **** as your description ?
i'm looking towards to hi-fi amplifier if there is X.x