Author Topic: Question about using an audio probe  (Read 393 times)

Marcseo

Question about using an audio probe
« on: October 29, 2020, 04:31:55 AM »
Hi, I am quite new to pedal debugging, although I have built by now a bunch of pedals.

I am curious about what are all the uses for an audio probe. At the moment I have a Sea Machine clone by Fuzzdog that doesn't work as it should but I am getting signal and some effect depending on how I set the knobs (it sounds more like a slapback delay than a chorus). I was wondering if an audio probe can help when you have a similar problem, as I believe audioprobes only work if the pedal makes no sound altogether.

This weekend I will be spending some time trying to find the issue and besides reading the ICs values, I don't know what else I can do (of course checking all components are on the right position etc). And as I have never built nor use an audio probe, I was curious if in this particular case it would be of any help.

I also have a Bionic Fuzz Gun clone that makes no sound, but I believe that is cause I broke the dpdt switch when soldering it, so I am waiting for a replacement, and I do want to try the audioprobe on this design.

Thanks in advance!

11-90-an

Re: Question about using an audio probe
« Reply #1 on: October 29, 2020, 05:26:36 AM »
an audio probe is basically useful for everything. not only pedals without sounds.
you can, for example, in a noisy pedal, can see which portion is when all the noise is added.
you can also check portions of the pedal which you think should have an effect (like chorus). so if you can't hear any chorusing, then you could know that probably the "chorusing" part of the circuit doesn't work

again, it's very useful.
flip flop flip flop flip

Marcseo

Re: Question about using an audio probe
« Reply #2 on: October 29, 2020, 07:27:32 AM »
Cool, I was thinking it was only for pedals that have no output.


Lets see if I can understand anything on the schematic in order to find the faulty components

Kevin Mitchell

Re: Question about using an audio probe
« Reply #3 on: October 29, 2020, 01:32:54 PM »
(it sounds more like a slapback delay than a chorus). I was wondering if an audio probe can help when you have a similar problem, as I believe audioprobes only work if the pedal makes no sound altogether.
Actually, that's a sign that the clock speed is too long. An audio probe can't help you there. I'm not familiar with that circuit or digital delays so I can't tell you anything other than to check your part values around IC3.

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11-90-an

Re: Question about using an audio probe
« Reply #4 on: October 29, 2020, 10:52:21 PM »
The sea machine is a pt2399 chorus, check madbean’s gravity wave:

https://www.madbeanpedals.com/EP/schematics/GravityWave.gif

My guess would be that you have some part values wrong near pin 6 of the pt2399 ic
flip flop flip flop flip

anotherjim

Re: Question about using an audio probe
« Reply #5 on: October 30, 2020, 05:50:44 AM »
If it is like that Gravity Wave, there is more chance of the RMS Titanic docking in New York harbour today than it producing a proper chorus effect.
R20 is the problem at 2k2. This is a safe value from the PT2399 datasheet, but the delay range it gives is too long for chorus and more like a slapback delay. You might reduce the resistor to 1k or even 510R and get away with it, but there is a danger of the PT2399 chip locking up if you push it too hard.
Additionally for chorus, you want delay time modulation working or else it is just delay you will hear.
Croeso i Diystompboxes.

If they didn't hear you then you didn't say it.

11-90-an

Re: Question about using an audio probe
« Reply #6 on: October 30, 2020, 07:29:40 AM »
If it is like that Gravity Wave, there is more chance of the RMS Titanic docking in New York harbour today than it producing a proper chorus effect.
R20 is the problem at 2k2. This is a safe value from the PT2399 datasheet, but the delay range it gives is too long for chorus and more like a slapback delay. You might reduce the resistor to 1k or even 510R and get away with it, but there is a danger of the PT2399 chip locking up if you push it too hard.
Additionally for chorus, you want delay time modulation working or else it is just delay you will hear.

it's probably the LFO portion... if the 2k2 resistor is the problem then all the others who built it would probably be complaining... I think
flip flop flip flop flip