Electro-Harmonix Freedom Amp -- fizz on all notes

[J M Fahey]

Does your scope capture show

tone & bite at zero

or some other setting?

IF it shows the buzzy setting, look elsewhere , not an electronic problem, that waveform is "Fender clean".
In that case itīs a speaker problem or even some weird cabinet resonance, I have fought those gremlins too.

IF amp is doing something nasty, it WILL show in the waveform.
So far , nothing to write home about.

[xtian]

I hear you...but it's NOT the speaker or cabinet. I suspected the speaker first, so I removed the amp from the cabinet, and played thru my test rig.

I also monitored battery voltage during playing--stays unchanged at 12.6v.

I'll get back to this next week when new LM317 and caps arrive--I'm looking forward to using my new solder vacuum!

[g1]

For when you get back at it:
When you did the scope capture in post #7, where you also monitoring the audio?
If not, try scoping the speaker while it's making the bad sound, preferably with a test tone. Like JM said, if the amp is doing it, something more ugly should show up on the scope.

[J M Fahey]

Yes, thatīs too mild.
Audible fuzz is much uglier

[xtian]

Parts arrived, so I replaced the LM317 (measured fine out of circuit) and all the e-caps. I LOVE my desoldering vacuum! But, this didn't change the amp's behavior.

So, back to the top. The amp has a pre-amp out jack, so I plugged that into another amp, and I can hear the same distortion as on the internal speaker. Next, because the internal speaker stays on when you plug into the pre-amp out jack, I disconnected the internal speaker, listening only through the external amp. Hey! No distortion! Let me restate this: with no speaker connected, amp sounds good via the pre-amp out jack; with speaker connected, signal is distorted. One last confirmation: instead of the speaker, I connected a 4-ohm resistor. Same result.

I tried again to capture this on scope and failed.