Trying to get two sound circuits work together

[Rorut]

I got two pcbs DIY.
- one is a circuit that makedifferent sound effects. I built it and it works great. I wanted to add delay to it and got a delay based on PT2399.

as it is now i think the sound gets distorted when the sound effects is connected to the delay board.
even if I have pots not turned up.

any ideas?

both circuits attached.

 

[gophert]

The PT2399 is an old chip, no longer in production and it never worked very well to begin with. It digitizes the analog input, writes it to a register, keeps doing that until the registers are full and then the voltages are sent out to a digital to analog converter in a FIFO bucket-brigade format.

High frequencies are lost and the dynamic range is a bit compressed and some hiss/buzz may be added for your listening pleasure. The longer the delay, the more high frequencies are lost.

also, you may be getting a type of "aliasing" Which is an interference patternbetween a digitally generated sound effect and a digitally collected signal near the same frequency or some harmonic of the signal.

the best way to handle the volume is to connect a pot between the output of the PT-2399 and ground, then use the output of the POT wiper as the source for your audio mixing.

 

[audioguru]

The minimum supply for a TL072 is 7V but yours is only 5V which is too low.
When an input gets within a few volts from ground in your circuit then the output DC goes as high as it can go.

 

[Rorut]

The minimum supply for a TL072 is 7V but yours is only 5V which is too low.
When an input gets within a few volts from ground in your circuit then the output DC goes as high as it can go.

Im using a 9V supply and also tested a 12V. Is it the 78L05 that has an output of 5V? Can I just remove that voltage regulator and use 9-12V ?
And that maybe could remove som of the distortion.

powering it with 12V i can measure 4.9V on the output from the TL072. Read that PT2399 should be powered with 5V

 

[audioguru]

If a 12V wall-wart powers the TL072 then it might produce some hum. Use the 7809 to power the TL072 for no hum.
Power the PT2399 with the 5V from the 78L05.

 

[Rorut]

If a 12V wall-wart powers the TL072 then it might produce some hum. Use the 7809 to power the TL072 for no hum.
Power the PT2399 with the 5V from the 78L05.

I will get a 7809 and try that. Thanks a lot!
Is there any other IC that can replace TL072 with lower input voltage?

Else there should not be any problems having these circuits together powered with the same 12V supply. Could it be any level issues, like the delay circuit getting to high input?

 

[audioguru]

Your siren circuit already has a 7809. The TL072 is an audio dual opamp with low noise. There are other dual opamps that can be powered by 5V but they produce lots of hiss noise.

 

[Rorut]

Your siren circuit already has a 7809. The TL072 is an audio dual opamp with low noise. There are other dual opamps that can be powered by 5V but they produce lots of hiss noise.

Perfect so just power pin 8 on the TL072 from the 7809 and Im fine?

 

[audioguru]

R8 must also be powered from the same 9V as pin 8 on the TL072. The 7809 for your siren has the correct input and output capacitors it needs.