Good morning to everyone
Im going to build a GC using LM3886 and i have some questions about it. Please if someone can help...?
1. I'm going to use it with 4 Ohm speaker, as far as i read i have to use +/_ 28Volts is this right?
2. Im going to use two transformers one for each channel. How many VA sould be each?
3. Finally can anyone tell me what kind of circuit do i have to connect to Pin No 8? (Mute).
Thanks in advance
Chris
Im going to build a GC using LM3886 and i have some questions about it. Please if someone can help...?
1. I'm going to use it with 4 Ohm speaker, as far as i read i have to use +/_ 28Volts is this right?
2. Im going to use two transformers one for each channel. How many VA sould be each?
3. Finally can anyone tell me what kind of circuit do i have to connect to Pin No 8? (Mute).
Thanks in advance
Chris
http://www.national.com/an/AN/AN-898.pdf
http://www.national.com/an/AN/AN-1192.pdf
http://www.national.com/appinfo/audio/files/Overture_Design_Guide13.xls
http://www.national.com/ds/LM/LM3886.pdf
The third file helps you a lot I imagine.
Mute circuit is described in AN-1192 and in datasheet. You just need a resistor + cap but you aren't forced to use it.
Maybe these links can help you a bit?
http://www.national.com/an/AN/AN-1192.pdf
http://www.national.com/appinfo/audio/files/Overture_Design_Guide13.xls
http://www.national.com/ds/LM/LM3886.pdf
The third file helps you a lot I imagine.
Mute circuit is described in AN-1192 and in datasheet. You just need a resistor + cap but you aren't forced to use it.
Maybe these links can help you a bit?
No cap needed.
They say yes, I say no.😱
Just connect a 10k resistor from the Mute pin to V-.😉
For transformers, 2x22v 200VA will be fine.
You need two of these.
They say yes, I say no.😱
Just connect a 10k resistor from the Mute pin to V-.😉
For transformers, 2x22v 200VA will be fine.
You need two of these.
satelitis said:
peranders said:
You need the resistor to draw current out of pin 8, which disables the mute. At turn on, the capacitor slowly ramps up the amount of current the resistor can draw. This keeps the amp muted while the rails of the power supply stabilise.
Guys, this has been discussed here on the forum some time ago.
We got to the conclusion that a 10k resistor is enough, no cap needed.
Meanwhile, National released the new LM4780.
Take a look at the datasheet of this chip.
You'll be surprized.
Maby National engineers are reading these threads.😀
BTW, even without the cap, no power on/off thump.
We got to the conclusion that a 10k resistor is enough, no cap needed.
Meanwhile, National released the new LM4780.
Take a look at the datasheet of this chip.
You'll be surprized.
Maby National engineers are reading these threads.😀
BTW, even without the cap, no power on/off thump.
Tazzy said:
I designed a PCB for LM4780:
http://hepso.dna.fi/misc/lm4780/lm4780_amplifier.html
And measured my prototype with RMAA. The results are limited by my USB DAC & ADC.
http://hepso.dna.fi/misc/lm4780/lm4780_rmaa.htm
Perfect !!!
Thank you very much all of you 🙂
I have already build both channels. The transformers are on the way to my place so you are going to hear more news soon.
Thanks again
Chris
Thank you very much all of you 🙂
I have already build both channels. The transformers are on the way to my place so you are going to hear more news soon.
Thanks again
Chris
Congratulations Chris.
Have you tried them?
Do you have a psu for testing?
If you're going to test with the new transformers, use a fuse.
Something can go wrong...
Murphy's law.😀
Have you tried them?
Do you have a psu for testing?
If you're going to test with the new transformers, use a fuse.
Something can go wrong...
Murphy's law.😀
Soon...
Yes I have already try it with a small torroidal transformer (2x20v 100 VA) just to to chek if everything is ok. Fortunately both channel are working perfect an i dont have any self oscillations Hummm etc.
In a few days I will have also the aluminium parts for the chasis and then .... 🙂
I will post some pics later .
The whole story started because I have a Pass Zen 4 and Im very satified with it but sometimes i would like to have some more power. On the other hand the GC is cheap enough (some versions not) and very easy to built so i said to my self "lets give a try", thats all.
Ciao
Chris
Yes I have already try it with a small torroidal transformer (2x20v 100 VA) just to to chek if everything is ok. Fortunately both channel are working perfect an i dont have any self oscillations Hummm etc.
In a few days I will have also the aluminium parts for the chasis and then .... 🙂
I will post some pics later .
The whole story started because I have a Pass Zen 4 and Im very satified with it but sometimes i would like to have some more power. On the other hand the GC is cheap enough (some versions not) and very easy to built so i said to my self "lets give a try", thats all.
Ciao
Chris
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