Using LM324 for active crossover?

[intelceleronman]

Hi

I have trying to make a active crossover with the lm324 chip. It does not work really great, there is a lot of static in the sound.

Is the LM324 suitable to this?

 

[peranders]

Frankly, LM324 is VERY unsuitable for audio! Why? The opamp has class B output stage (heavy crossover distortion) and it is slow (even heavier crossover distortion).

LM324 is good for many things things but not audio, not even low-fi audio.

 

[intelceleronman]

Well I am glad to hear that.

What must I use? I have seen some thing like TL74.

Thanks

 

[paulb]

The only benefit to the LM324, in any application, is that it's dirt cheap.
The TL074 is a reasonable one to start with. Recommend you use sockets to try other opamps (then maybe solder your choice in).

 

[intelceleronman]

The only benefit to the LM324, in any application, is that it;s dirt cheap.

Thats why I got it

But the TL74 is almost as cheap so I will get that.

Thanks.

 

[intelceleronman]

Ok so I got a TL74 op-amp. I have build a low pass using one opamp. I am powering it from a pc psu to get +12/-12. The problem is that I there is static on the output, is this because it is a switching psu? Is it better to use a psu that has a transformer in?

Thanks

 

[intelceleronman]

Anyone?

 

[peranders]

I think you have mixed something up. It's possible to use a switched power supply if you do it right and the supply is good but normally they must be very modern and have little RF emission.

Don't forget to tie the minus input to the output and plus input down to ground for all unused opamps!

 

[audioPT]

Why don't you use NE5532 (Dual opamp)?
It's cheap and VERY GOOD for AUDIO!

Per-Anders, do you agree?

Regards

Pedro Martins

 

[paulb]

Hi

I have trying to make a active crossover with the lm324 chip. It does not work really great, there is a lot of static in the sound.

Is the LM324 suitable to this?

Ok so I got a TL74 op-amp. I have build a low pass using one opamp. I am powering it from a pc psu to get +12/-12. The problem is that I there is static on the output, is this because it is a switching psu? Is it better to use a psu that has a transformer in?

Thanks

Is the static the same with the two different types? You probably have a grounding problem or the power supply is too noisy. Also, most PC power supplies need a minimum load and it may not be operating properly because of this. It may be creating the "static." You could also try the filter below, even substituting resistors for the inductors. Thanks to Rod Elliot at ESP (Project 69) for the filter schematic.

 

[peranders]

Ok so I got a TL74 op-amp. I have build a low pass using one opamp. I am powering it from a pc psu to get +12/-12. The problem is that I there is static on the output, is this because it is a switching psu? Is it better to use a psu that has a transformer in?

Thanks

I didn't read carefully, PC power supply! Some PC PS must be loaded with a minimum load, otherwise they won't work! This minimum load is several ampere sometimes!

What is "static"? Explain please.

 

[intelceleronman]

Hi

I have connected two 1mh inductors like in the pic, it does take away the static I was talking about. But there is still other noises on the output. If I use a center tapped transformer must the center tap be connected to the signal ground?

I have connected two 9 volt batterys to get 9v-0-9v and it has almost no static.

So what will be the best power supply to build for it? Since a pc psu is out?

Thanks again