Weird audio Amp problem...

[jjj]

Yes, it could be that the 100W needs a stronger input signal. That's why it acts so weird with a weak signal. In that case I would need to amplify the strengthen the reverb signal. The Chinese sell some low Watt PreAmps. (Maybe 2W might suffice?) Yet, then again it might be something else? Maybe even me!
Well, for now I found a poor, yet satisfactory solution, which at least enables me to happily perform until I personally meet an admirer of my musical art, who's willing and able to check out what's wrong with it.
So, I'm truly grateful for all your wonderful help... in this case it's just me who's unable to help myself.
One final question:
how can I automate this power "kick-start" madness? The Chinese sell cheap timers with RLY. The problem there's that the speaker needs to be first disconnected and reconnected last.

[jjj]

The last 4 days it was raining non-stop here in Townsville Qld.4814 and that gave me a chance to investigate the problem further.
Result: After I disconnected the ETI Howlround (which I built) the problem is no more. It worked for 20 years, but now I ask myself what has gone wrong wit it?
What might causing it. At that time I only added a 12V negative voltage generator, albeit it should have been +/-15V.
I (twice) tried to upload the magazine in which the ETI Howlround is featured, but this forum's application rejects its upload.

Here's a box.com upload of it: https://app.box.com/s/em8ggpmmp1pwfh3y1dyq5tlwt8s1mzom

I also included a Pic of my improvised hardware...
Maybe this cheap Frq shifter will do the job:
https://www.aliexpress.com/item/Free-Shipping-1pc-AD303-frequency-shift-anti-whistle-module-Microphone-howling-suppressor/1568429213.html?spm=2114.search0104.3.1.6bfa6b0ap3QhyA&w s_ab_test=searchweb0_0,searchweb201602_3_10065_10068_101 30_10547_319_317_10548_10696_453_10084_454_10083_433_106 18_431_10307_537_536_10131_10902_10132_10133_10059_10884 _10887_321_322_10103,searchweb201603_54,ppcSwitch_0&algo _expid=ea2a3542-8545-4cd4-817d-a79a45b520eb-0&algo_pvid=ea2a3542-8545-4cd4-817d-a79a45b520eb&transAbTest=ae803_5

[J M Fahey]

Result: After I disconnected the ETI Howlround (which I built) the problem is no more. It worked for 20 years, but now I ask myself what has gone wrong wit it?

Which was suggested .... ummmmm ..... in post #3

[nickb]

Just the relevant section from the magazine:

Howl.pdf


This thread's a hoot (pun intended)!