adjusting mic circuit for guitar help please

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hello,

I have this mic reverb circuit im trying to adapt for guitar. I have studied how to make the delay time longer. i think the inputs are fine with mic's, just no good for guitar. i get alot of noise.
its on a pcb so if any one can see adjustments that could be worth trying that would be great thanks.
Im can replace components and values and make whatever cuts and jumps if it might make it work for guitar,

cheers
 

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See page 3 of the data sheet: PT2399 Datasheet
Increase R on pin #6 of IC2, up to 50k maximum.
There's a table on page 5 for R values up to 27k.

Thankyou for Replying. I understand how to implement that adjustment the pin 6 delay rate adjustment by adding a potentiometer.
the problem i think is that the input and amplification is designed for microphone. is it normal for the power supply it be connected to the input signal or is that why it creates alot of noise when i try to use it with guitar? cheers
 
See page 3 of the data sheet: PT2399 Datasheet
Increase R on pin #6 of IC2, up to 50k maximum.
There's a table on page 5 for R values up to 27k.

That is the most bizarre data sheet I've ever seen. Better described as a data free sheet. This one is a _little_ better.

http://www.princeton.com.tw/Portals/0/Product/PT2399_1.pdf

At least we know the power supply Voltage and power consumption and the audio level expected but I see no description of what happens when overdriven. Do you have to worry about blowing the input amp if you get too loud?

 
As far as I see it that circuit has inputs for Electret microphones, so it feeds them +5V through a couple 10k resistors.

You would have to modify so much as to make that board useless.
Did you pull it from a Karaoke machine?

I strongly suggest you build one of the **Guitar** pedal PT2399 delay projects out there, some require you to etch and drill your own PCB, others can be built on hobbyist/eperimenter perfboard or stripboard.

You can pull the PT2399 and even more parts and mount them on the new board.

Just one very good sounding project:
Madbean+Cave+Dweller.png


Guitar FX Layouts: Madbean Cave Dweller

KILLER eerie spaced out sounds:
https://www.youtube.com/watch?v=La6IAW1HvKM
 
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is it normal for the power supply it be connected to the input signal or is that why it creates a lot of noise when i try to use it with guitar?

Yes, and probably yes.

Electret microphones need a power source, and many times they use the signal line as the power line. SO if that is what this was designed for, that would explain the DC there.

Having a few volts of DC on the input can surely make noise, your guitar pickups won;t like it. Try adding a series cap between guitar and input point. That will block DC.

Where did you get this board? From a boom box or karaoke machine? I have a feeling it was from something pretty minimal.

The input IC is a 4558 running on a single 9v supply, so unless your guitar peaks over about 4.5v, you won;t over run the inputs with signal. Plus at the input there is voltage division with the 2.2k and 5.6k resistors, which drop the signal to about 70% before the chip. A pair of clamp diodes would protect against that if there is concern.
 
Yes, and probably yes.

Electret microphones need a power source, and many times they use the signal line as the power line. SO if that is what this was designed for, that would explain the DC there.

Having a few volts of DC on the input can surely make noise, your guitar pickups won;t like it. Try adding a series cap between guitar and input point. That will block DC.

Where did you get this board? From a boom box or karaoke machine? I have a feeling it was from something pretty minimal.

The input IC is a 4558 running on a single 9v supply, so unless your guitar peaks over about 4.5v, you won;t over run the inputs with signal. Plus at the input there is voltage division with the 2.2k and 5.6k resistors, which drop the signal to about 70% before the chip. A pair of clamp diodes would protect against that if there is concern.

thanks for replying. its a cheapo $5 diy kit karaoke board and parts, i'm too budget to buy a delay.
what value cap would you recommend and does it have to be electrolytic?
if it still doesnt work i will probably try mic the amp and feed the signal back in the amp if it doesnt feed back,

cheers
 

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As far as I see it that circuit has inputs for Electret microphones, so it feeds them +5V through a couple 10k resistors.

You would have to modify so much as to make that board useless.
Did you pull it from a Karaoke machine?

I strongly suggest you build one of the **Guitar** pedal PT2399 delay projects out there, some require you to etch and drill your own PCB, others can be built on hobbyist/eperimenter perfboard or stripboard.

Hello,
I ordered this one as a cheapo kit because all the delay vero's i looked at were going to take to long to build,
that one looks simple to build I will have a go at building it when a get a couple of ic's,
thanks
 
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On each mic input, add a series 10uF, 16V (or more) nonpolarized electrolytic.

Thanks for ever ones help.
for people who want to muck with cheap mic delay kit for guitar.

i cut both the + tracks on the two mic input jacks.
#across one cut i used the non polarized 10uf 16v (the only NP cap i have) for the input
#the other jack i did not bridge track cut. I ran a jumper wire from the audio output to the + on the jack socket and used it as my ouput to amp. no noise issue.

I also removed the resistor from pin 6 to gound (pt2399) and used a 1 or 2k resistor in series with a 50k pot to ground. 50k is a bit much rain noise when you turn it that far.

I got a clean kind of country sound from it. the output is very strong but i guess it is ment to be a line level signal not an instrument level.

I couldnt really appreciate its cheap shityness until i ran distortion+ delay from multi effects unit through it then ran it through the analog delay built in the amp.
with the distortion and three delays i managed to get and early eighties new wave rock kind of punk sound i have heard on some recordings from way back when and remember wondering how they had got that sound.

the delay is really really hard on battery's but for a bit of extra sustain or something with other effects its ok i guess. if i ever got another kit to build someone a cheap b-day present it would be the one with 3or 4 knobs so i dont have to waste my own parts on it.
 
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