How to measure the freq. range of low cut and high cut fillters of an effect pedal?

[George]

Hi guys,
I have a Yamaha Magicstomp that has a deep edit feature where you can edit the patches through a USB port.

One of the effects is called "8 Multi Tap Mod Delay" and there you can set the low cut and high cut filters between 0 (off) and 10. I would like to know what is the range of frequencies that these filters operate.

The manual doesn't say anything about it, I contacted US Yamaha support, they don't have this info either.

(It is interesting that there are other patches or effects in the same unit that utilizes Low pass and High pass filters, there you can set the exact frequency and specs for them are given in the manual.)

So, is there any way to figure out or measure what frequency range the low cut and high cut filters operate?

[Brad1]

Hi guys,

One of the effects is called "8 Multi Tap Mod Delay" and there you can set the low cut and high cut filters between 0 (off) and 10. I would like to know what is the range of frequencies that these filters operate.

The manual doesn't say anything about it, I contacted US Yamaha support, they don't have this info either.

(It is interesting that there are other patches or effects in the same unit that utilizes Low pass and High pass filters, there you can set the exact frequency and specs for them are given in the manual.)

Is it possible that they are the same filter(s), just used combined with Delay preset? Does each "multi-tap" have it's own parameter setting on that, thereby giving each tap a different one?

Do all the others have a certain same default setting, or have they been preset by Yamaha as their best guess of what is good for that particular combination of effects, and threw in ability to tweak from there?

Brad1

[George]

"Is it possible that they are the same filter(s), just used combined with Delay preset?"

I don't know.

"Does each "multi-tap" have it's own parameter setting on that, thereby giving each tap a different one?"

Yes and no, each tap has it's own settings but the first tap has all the major settings, the settings of the other 7 is limited, the EQ part can be set only on the 1st page (tap) but I'm assuming that it effects the rest of the taps since you cannot set those for them. Here you can see the several screenshots of the editor related to this subject:
https://tinyurl.com/p3a3g7u
I attached the page for tap-1 and for tap-2 only because all others are the same as tap-2 as far as the control knob availability goes.

[Rixen]

yes, you can measure. You will need access to a function generator (apps are available for smartphones and) either an oscilloscope (also apps available for smartphones, albeit with limited bandwidth) or an AC voltmeter with wide bandwidth. Then it's just a matter of finding the frequencies where there is a drop of 30% of the output voltage..

maybe someone knows of a good soundcard based solution for sweeping filters etc ?

Julian
Rixenpedals

[George]

I found this great website today, where you can download all of the above mentioned windows utilities 100% free:
Program Information

The dual function generator can generate all kind of wave forms like sine, square, triangle, noise, ramp, nramp between 2Hz and 20kHz.

The dual channel scope can pick up the signal from your soundcard or any other audio input device in your PC, in my case I set it up to pick up audio from my USB microphone and as a test the scope displayed beautifully the graph of my whistling or coughing when I had the mic directed to the speaker both in the function of time or frequency.

Now I just have to learn how to what I want to do.

Before I would plug my soundcard line out port to my guitar effect pedal let me ask you this: The effect gear has a Low and High input option, normally you have to plug your Fender Stratocaster in the High input port, but in case of a soundcard, where should I plug that one in so I won't overload and destroy the input section of my Yamaha Magicstomp? Or should I look at the specs of the Magicstomp and include it here before you can answer that question?

Do I have to measure the voltage of my Line out of my soundcard and maybe set the voltage (volume level) to a certain value so that it won't kill my effect gear?


Oh, and almost forgot, that on the same wesite I found this diagram:
http://www.hotamateurprograms.com/EE...0Interface.jpg

Is this what I need to be able to hook up the line out port of my soundcard to the effect gear? ( for signal input)

[Rixen]

The input sensitivity of the Magicstomp is quoted in the specs as being -15dBm (Low) and -25dBm (Hi) into 1M Ohm. If I have worked it out correctly that is 5.6V and 1.8V respectively.

Line level signals will be fine going into that, but if you want to be extra safe then put a 10k resistor in series with the signal line. I don't think you need to build the interface circuit

that is some useful looking software you found, George, thanks !

Julian
Rixen Pedals

[George]

that is some useful looking software you found, George, thanks !
Rixen Pedals

I know! I was also shocked to find them after a 2 min. Google search. It was like God finally listened to my prayer and voila, there they were.

Which port on the Magicstomp should I connect my soundcard's "Line out" port to using the 10k resistor, the Low, or High or it doesn't matter?

Right now I have my Magicstomp apart because I'm in the middle of installing a cooling fan in it, once I got all the necessary parts, I'll put it back together and I'll be ready to do the measuring the low and high cut filters of the Magicstomp, max. a week from now on.

[Rixen]

I'd connect to the low, but you can try both. If the signal level is too high it will just clip and distort.

cheers,

Julian

Rixen Pedals

[George]

OK, thank you Julian for the help, "I'll be back" as soon I finished the cooling fan project.