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PT2399 Echo Processor

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aljamri

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Hi,

I'm using PT2399 Echo Processor IC to provide echo to my speakers (datasheet attached). I'm using the circuit in page 3 (echo application circuit).

The problem is the quality of the output sound is not fine. It tend to give a lot of bass which changes the real sound.

Any suggestions to improve the circuit ? or any alternative IC is available?

Thanks
 

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You need to study the dataheet and try to optimize the design by controlling the component tolerences. It appears to me chip is reasonably ok.
 
The 15k resistor in series with the input then a 3900pF capacitor to ground cuts 2735Hz to -3db and higher frequencies are cut more.

Maybe the filtering away of all the high frequencies reduces whistles.

It is the only audio IC datasheet that I have seen that doesn't mention frequency response.
 
more information

audioguru said:
The 15k resistor in series with the input then a 3900pF capacitor to ground cuts 2735Hz to -3db and higher frequencies are cut more.

Maybe the filtering away of all the high frequencies reduces whistles.

No there is no whistles. Something I forgot to mention:

- I used LM358 as a pre-amplifier, is it possible that this what makes the sound so noisy?

- Somewhere else, I read that the 20k:eek:hm: and 50k:eek:hm: variable resistors have to be one linear and the other audio (may be logarithmic). My question how can I differentiate.

- For the above variable resistors i used similar type and value (50k:eek:hm: )

Thanks :confused:
 
have you used it ?

mvs sarma said:
You need to study the dataheet and try to optimize the design by controlling the component tolerences. It appears to me chip is reasonably ok.

thanks for you reply. have you used it ? :confused:
 
LM358? -- you try to by pass and see whether it improves leave alone the gain part of it
 
The lousy old LM358 is half an old LM324 quad opamp.
They are the first low-power opamps.
Their low current causes noise and crossover distortion.
Their output cannot swing at high level above only 5kHz.

I use TL071 single, TL072 dual and TL074 quad low noise, low distortion and wideband (100kHz) opamps for audio.
 
pin-to-pin replacement ?

audioguru said:
The lousy old LM358 is half an old LM324 quad opamp.
They are the first low-power opamps.
Their low current causes noise and crossover distortion.
Their output cannot swing at high level above only 5kHz.

I use TL071 single, TL072 dual and TL074 quad low noise, low distortion and wideband (100kHz) opamps for audio.


so do you suggest to replace LM358 with TL072 ? is it pin-to-pin replacement ? :confused:

thanks
 
Datasheets

comparing the two datasheet they are the same except for pin #4 that called Gnd in LM358 and Vcc- for TL072.

For supply i could not make it out, is it 16 and 18 respectivly ? in my circuit there is no -ve source for LM358 ??
 

Attachments

  • LM358.pdf
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  • TL072CP.pdf
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aljamri said:
so do you suggest to replace LM358 with TL072 ? is it pin-to-pin replacement ? :confused:
The pins numbers are exactly the same.
Use a lousy old LM358 if you want want hiss and crossover distortion, or use a low noise TL072 if you want high quality. I think they cost the same, peanuts.

You forgot to post the schematic of your preamp so we can't see if the opamps are biased correctly for a TL072 to be used. A TL072 doesn't need a negative supply if its inputs are biased at half the supply voltage and coupling capacitors are used.

The minimum recommended supply voltage for the TL072 is 7V.

The TL071 is a single opamp, the TL072 is a dual and the TL074 is a quad.
 
good resutl !

audioguru said:
The pins numbers are exactly the same.
Use a lousy old LM358 if you want want hiss and crossover distortion, or use a low noise TL072 if you want high quality. I think they cost the same, peanuts.

I repalced my LM358 with TL072 pin to pin and very good result, although if it is a bit more would be better.

my next step is to build the circuit with out a preamplifier and see the abilities of the PT2399.

Thanks for your intrest. TL072 costs my $0.55 only from Futurlec.com.
 
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