If you dun wanna use a pot...use a 50K resistor and tie it to ground...and remember to attach an 8ohm power resistor before trying to measure any offset...
li_gangyi said:
hmm... ok.... and perhaps a capacitor on the outputs.. 🙂 just to be abit safer... and maybe a.... umm.. I forgot what I was saying..
lol lol lol lol!!!!
Hey SkinnyBoy,
As Christer said, you NEED to put a resistor (say, 47k) on the RCA inputs (from + to ground).
If you don't have a pot, you need this.
DON'T CONNECT THE AMP TO ANY SPEAKER BEFORE DOING THIS!!!😱
23v DC offset may kill any speaker.
Oh, and you should put an input cap.
It's not big.
Nothing on the output.
Oh, BTW, don't put water on this one.
Hey SkinnyBoy,
As Christer said, you NEED to put a resistor (say, 47k) on the RCA inputs (from + to ground).
If you don't have a pot, you need this.
DON'T CONNECT THE AMP TO ANY SPEAKER BEFORE DOING THIS!!!😱
23v DC offset may kill any speaker.
Oh, and you should put an input cap.
It's not big.
Nothing on the output.
Oh, BTW, don't put water on this one.
Re: lol lol lol lol!!!!
I already connected it to a speaker... an old 4inch driver.. and unpluged the input.. lol
carlosfm said:Hey SkinnyBoy,
As Christer said, you NEED to put a resistor (say, 47k) on the RCA inputs (from + to ground).
If you don't have a pot, you need this.
DON'T CONNECT THE AMP TO ANY SPEAKER BEFORE DOING THIS!!!😱
23v DC offset may kill any speaker.
Oh, and you should put an input cap.
It's not big.
Nothing on the output.
Oh, BTW, don't put water on this one.
I already connected it to a speaker... an old 4inch driver.. and unpluged the input.. lol
Skinnyman, have you made any troubleshooting?
1 Connect exactly as the schematic
2 Check the component values
3 Ground the input via a 10-47 k resistor
4 Connect nothing to the output
5 Measure all voltages with a DMM. Post the result to us.
6 Read carefully the datasheet and AN-1192
7 Take a photo of it and post it here
With the connection you have chosen you will get less than 300 mV offset I'll guess.
Skinnyboy, we talked about learning in an another thread, this LM3886 happens to have an excellent application note and I think you should read it carefully and try to understand it. DC-paths for the inputs ARE ESSENTIAL! If you don't understand why, just trust us. Meaning you must have a pull down resistor when you test this amp with no signal source. It's also wise to have all times just case the amp is switched on and the input is disconnected.
1 Connect exactly as the schematic
2 Check the component values
3 Ground the input via a 10-47 k resistor
4 Connect nothing to the output
5 Measure all voltages with a DMM. Post the result to us.
6 Read carefully the datasheet and AN-1192
7 Take a photo of it and post it here
With the connection you have chosen you will get less than 300 mV offset I'll guess.
Skinnyboy, we talked about learning in an another thread, this LM3886 happens to have an excellent application note and I think you should read it carefully and try to understand it. DC-paths for the inputs ARE ESSENTIAL! If you don't understand why, just trust us. Meaning you must have a pull down resistor when you test this amp with no signal source. It's also wise to have all times just case the amp is switched on and the input is disconnected.
Re: Re: Re: lol lol lol lol!!!!
no bang... the speaker cone went in about 3mm, and sat there hovering....
I haven't connected the resistor yet, ok? it was like midnight... 🙄
1. The circuit is connected correctly
2. I chose those component values at randon (well, almost) as I didn't have the ones in the diagram...
3. I shorted the input to ground (with the CD players output) and measured about 45mV ofset
my digital camera is rubbish... I'll take pics anyway.. everything is once again mounted across the chip.. 🙂
Thanx for the help.. I'll connect a 47ohm (I probably don't have any) resistor across the input...
carlosfm said:
no bang... the speaker cone went in about 3mm, and sat there hovering....
peranders said:
I haven't connected the resistor yet, ok? it was like midnight... 🙄
1. The circuit is connected correctly
2. I chose those component values at randon (well, almost) as I didn't have the ones in the diagram...
3. I shorted the input to ground (with the CD players output) and measured about 45mV ofset
my digital camera is rubbish... I'll take pics anyway.. everything is once again mounted across the chip.. 🙂
Thanx for the help.. I'll connect a 47ohm (I probably don't have any) resistor across the input...
Re: Re: Re: Re: lol lol lol lol!!!!
Probably just a typo, but in case it wasn't, the value shoould
rather be 47 kOhm.
SkinnyBoy said:
Probably just a typo, but in case it wasn't, the value shoould
rather be 47 kOhm.
Re: Re: Re: Re: Re: lol lol lol lol!!!!
It wasn't a typo.. 47k? thats pretty high.... I'll use something lower... closer to 10k 🙂
Christer said:
It wasn't a typo.. 47k? thats pretty high.... I'll use something lower... closer to 10k 🙂
I didn't have time to read all of the responces, but in the ones I read, I saw nothing related to the simple fix.
You said that the output voltage increases when an input source is connected. Portable and cheap CD players tend to put out a voltage in the output. I had the problem where when the CD player is turned on, the speaker would suck in about 1/2 inch then come back out with a pop sound. To fix it, I just placed a small cap inline with the input. I myself used 2uf. It solved the DC voltage problems.
Good luck, Mike
You said that the output voltage increases when an input source is connected. Portable and cheap CD players tend to put out a voltage in the output. I had the problem where when the CD player is turned on, the speaker would suck in about 1/2 inch then come back out with a pop sound. To fix it, I just placed a small cap inline with the input. I myself used 2uf. It solved the DC voltage problems.
Good luck, Mike
soundNERD said:
nah.. theres nothing wrong with it.. just my lack of electronics knowledge... lol...
Re: Re: Re: Re: Re: Re: lol lol lol lol!!!!
Probably works fine. My soundblaster card has no problem
driving headphones from the line output (not sure if that is
advisable, though).
However, you were very reluctant to put in the resistor at
all, and now you want a low value. A 47k is closer
to no resistor at all than 10k is.
SkinnyBoy said:
Probably works fine. My soundblaster card has no problem
driving headphones from the line output (not sure if that is
advisable, though).
However, you were very reluctant to put in the resistor at
all, and now you want a low value. A 47k is closer
to no resistor at all than 10k is.
SkinnyBoy said:
Maybe, if the bottom colour is blue, otherwise I can think of many
other more estethical values, to my taste, that is. 🙂
I would put a pot
Definitely.
The sound card is always to be kept at max volume.
That's because you loose 1 bit of resolution for every 6 db of digital attenuation.
SkinnyBoy, if you care about sound quality, put a pot on the amp and control the volume there.
Let the sound card at maximum volume.
Definitely.
The sound card is always to be kept at max volume.
That's because you loose 1 bit of resolution for every 6 db of digital attenuation.
SkinnyBoy, if you care about sound quality, put a pot on the amp and control the volume there.
Let the sound card at maximum volume.
Re: I would put a pot
my soundcard clips at maximum volume!! HAHAHA!! and anything about half way gets distorted... lol
I could always put a pot INTERNALLY... so.. the max volume on the soundcard is the max level I would listen to it (or the "normal" level, or the level at which the amp clips.. lol)
carlosfm said:Definitely.
The sound card is always to be kept at max volume.
That's because you loose 1 bit of resolution for every 6 db of digital attenuation.
SkinnyBoy, if you care about sound quality, put a pot on the amp and control the volume there.
Let the sound card at maximum volume.
my soundcard clips at maximum volume!! HAHAHA!! and anything about half way gets distorted... lol
I could always put a pot INTERNALLY... so.. the max volume on the soundcard is the max level I would listen to it (or the "normal" level, or the level at which the amp clips.. lol)
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