| Building a GC using LM3886 - Click HERE for Original Thread |
| satelitis |
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 |
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| carlosfm |
No cap needed.
They say yes, I say no.:eek:
Just connect a 10k resistor from the Mute pin to V-.;)
For transformers, 2x22v 200VA will be fine.
You need two of these. |
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| seangoesbonk |
| quote: | Originally posted by satelitis
...can anyone tell me what kind of circuit do i have to connect to Pin No 8? |
| quote: | Originally posted by peranders
You just need a resistor + cap but you aren't forced to use it. |
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. |
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| carlosfm |
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.:clown:
Maby National engineers are reading these threads.:D
BTW, even without the cap, no power on/off thump. |
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| Tazzy |
| How good are they? Should I ask for samples today? |
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| carlosfm |
| quote: | Originally posted by Tazzy
How good are they? Should I ask for samples today? |
Ask tomorrow.:devily: |
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| satelitis |
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 |
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| carlosfm |
Congratulations Chris.:drink:
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.:D |
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| satelitis |
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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| satelitis |
| So here are some pictures of both two channels. Im still waiting for the tranformers .... |
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