Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => AmpTools/Tech Tips => Topic started by: mopar39 on March 08, 2023, 11:06:31 am

Title: Reverb signal view on oscilloscope
Post by: mopar39 on March 08, 2023, 11:06:31 am
I'm a advanced beginner (oxymoron?) and was wondering what the oscilloscope trace should look like if I put a low volt sine wave through my tube amp.
Title: Re: Reverb signal view on oscilloscope
Post by: shooter on March 08, 2023, 11:19:24 am
from my last build
Title: Re: Reverb signal view on oscilloscope
Post by: sluckey on March 08, 2023, 11:22:01 am
I'm a advanced beginner (oxymoron?) and was wondering what the oscilloscope trace should look like if I put a low volt sine wave through my tube amp.
Good question. I wonder too.

A lot depends on how you trigger the scope and whether you're using a digital scope or an analog scope. For an analog scope if you trigger on the clean sinewave that you put into the amp, I would expect to see a clean sinewave that's in sync with the input signal. And I would also expect to see several out of sync sinewaves that appear to just be free running across the display.

A digital scope would probably just show several sinewaves.

Of course I'm just guessing. I've never looked at the reverb signal with a sinewave signal source. Why don't you try it and post a pic.
Title: Re: Reverb signal view on oscilloscope
Post by: mopar39 on March 08, 2023, 11:54:41 am
I will in the next couple days.  Thank You!
Title: Re: Reverb signal view on oscilloscope
Post by: shooter on March 08, 2023, 12:21:41 pm
Quote
I've never looked at the reverb signal with a sinewave signal source.
nope, me either


Quote
should look like if I put a low volt sine wave through my tube amp.


now that i've done and posted results  :icon_biggrin:



Title: Re: Reverb signal view on oscilloscope
Post by: HotBluePlates on April 08, 2023, 09:24:20 am
... I've never looked at the reverb signal with a sinewave signal source. ...

I've only ever looked at reverb on a phasemeter, which is a scope set up for X-Y display of the Left & Right channels of a mix buss.  With that, you see the reverb imparts a bunch of delays of various times, at somewhat lower level than the original sound (depending on your reverb settings, of course).

I don't think a steady sine is a great signal for observing anything about reverb, just as one held note on the guitar doesn't really let you hear the reverb effect.  A short impulse gives much more information, and might make the reverb trails easier to see on the scope.