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
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
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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.
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 ?
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 ?
Attachments
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,
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)
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)
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.
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.
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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.
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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 ?
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)
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
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)
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
If your looking for hifi, then forget all about chipamps and look over at the DX blame series, this is about as simple as a high performance amplifier can get.
As far as chipamps go, the LM3886 is pretty much as good as they get.
Theres also the LME49810 from National semi which only requires driver and output transistors and a VBE multiplier bias circuit to make a full working amplifier.
As far as chipamps go, the LM3886 is pretty much as good as they get.
Theres also the LME49810 from National semi which only requires driver and output transistors and a VBE multiplier bias circuit to make a full working amplifier.
This may sound weird to you, but i'm trying to get :
(I) hi-fi (or at least no hiss/hum/buzz (significant noise)) quality
(II)low-mid volume (well...... i'm not party boomer, typical 20W(rough figure) is already too much for me)
(III) Preferable Low operating voltage such as 12V and below (well..... i only have low voltage power supply now ^^)
Do you have any circuit/IC suggestion for me ? (maybe get no/very low noise first, then next project for hi-fi)
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You need to add output transistors as i said before, check the datasheet.
Why do you want low voltages like 12V or less ? at those voltages you cannot get good sound into a normal speaker.
Any amplifier i've seen with atleast a bit of sound quality ahve been atleast 2x25V split rails or 35-40V single rail.
Split or single rail below 12V, your looking at the old tda junk, old BTL car amplifier chipamps or headphone amplifiers. Even a bridged amplifier running at 12V is still only 10-15 watts at 10% THD into 2-4 ohms.
Many of the components in a amplifier circuit like constant current sources cannot be made to function satisfactory at such low voltages.
Build the DX trust, its rated at 20 watts maximum and its about as simple as a amplifier can get before looking at chipamps.
Link: http://users.tpg.com.au/users/gerskine/dxamp/dx trust schematic.pdf
Why do you want low voltages like 12V or less ? at those voltages you cannot get good sound into a normal speaker.
Any amplifier i've seen with atleast a bit of sound quality ahve been atleast 2x25V split rails or 35-40V single rail.
Split or single rail below 12V, your looking at the old tda junk, old BTL car amplifier chipamps or headphone amplifiers. Even a bridged amplifier running at 12V is still only 10-15 watts at 10% THD into 2-4 ohms.
Many of the components in a amplifier circuit like constant current sources cannot be made to function satisfactory at such low voltages.
Build the DX trust, its rated at 20 watts maximum and its about as simple as a amplifier can get before looking at chipamps.
Link: http://users.tpg.com.au/users/gerskine/dxamp/dx trust schematic.pdf
About that...... dual supply in 1 of the thing i avoid ^^ but i will look into it later
hm..... there is not any 12V noiseless amplifier circuit ? so sad...
the circuit you gave me is using 36V single rail power supply ?
well..... i need to build a good (not perfect) 36V power supply, can give me some link for supply ? its quite a hassle X.x
The DX amplifiers are dead quiet on idle when properly built.
Hiss is usually just caused by high gain which brings the noise of the input stage transistors up enough to be heard along with whats beeing picked up at the input.
Chipamps usually hiss because the internal circuit is just so terrible that it shouldent even work at all.
I assume you like single rail due to the sense of security of the output cap catching the dc offset when the amplifier fails.
I still much prefer split rails since that is how amplifiers are intended to work. Single rail was originally before they figured out how to make an amplifier properly, and is today only used in either really cheap and nasty mini systems or by ppl who prefers the sound of single rail and ac (capacitor) coupled output. on this end your looking mostly at amplifiers costing more than your car, weighting in at 20+ kilos, eating 500 watts on standby and still only produces about 1-5 watts of usable power into 4 ohms at 10-50% THD.
Hiss is usually just caused by high gain which brings the noise of the input stage transistors up enough to be heard along with whats beeing picked up at the input.
Chipamps usually hiss because the internal circuit is just so terrible that it shouldent even work at all.
I assume you like single rail due to the sense of security of the output cap catching the dc offset when the amplifier fails.
I still much prefer split rails since that is how amplifiers are intended to work. Single rail was originally before they figured out how to make an amplifier properly, and is today only used in either really cheap and nasty mini systems or by ppl who prefers the sound of single rail and ac (capacitor) coupled output. on this end your looking mostly at amplifiers costing more than your car, weighting in at 20+ kilos, eating 500 watts on standby and still only produces about 1-5 watts of usable power into 4 ohms at 10-50% THD.
lol..... that is kinda true about car audio ^^
hm.... you said about the split rail is better, what about the dx trust you recommended ? from what i saw, it is a single rail powered circuit. IF i use a dual supply, but only apply the common and positive to my amp, is it ok ?
About power supply, according to a link i saw
Also i saw a thing that i don't understand in the schematic of dx trust, a 'triangle' shape with label of 'A' !
Another thing was about the variable resistor, what is it for (to adjust what ?) and why it have 2 figure ? (normally i only met 1) and some resistor have alphabet in their value (eg.: 0R33)
one more, there is a capacitor have value of
6800uF to 8ohms or
8600uf to 4 ohms
If i want to make my amplifier flexible to use speaker load of 4/6/8 ohms at anytime, can i just use 8600uF then solve the problem ?
hm.... you said about the split rail is better, what about the dx trust you recommended ? from what i saw, it is a single rail powered circuit. IF i use a dual supply, but only apply the common and positive to my amp, is it ok ?
About power supply, according to a link i saw
It is essential to have an good supply for amplifier, so should i build according to the link, or build a DX PSU (on the link you gave me) ?
Also i saw a thing that i don't understand in the schematic of dx trust, a 'triangle' shape with label of 'A' !
Another thing was about the variable resistor, what is it for (to adjust what ?) and why it have 2 figure ? (normally i only met 1) and some resistor have alphabet in their value (eg.: 0R33)
one more, there is a capacitor have value of
6800uF to 8ohms or
8600uf to 4 ohms
If i want to make my amplifier flexible to use speaker load of 4/6/8 ohms at anytime, can i just use 8600uF then solve the problem ?
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